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EXPANDABLE LAST FOR FURNISHING FOOTWEAR WITH AN INSERT AND METHOD FOR FURNISHING FOOTWEAR WITH AN INSERT

20230320462 · 2023-10-12

    Inventors

    Cpc classification

    International classification

    Abstract

    An expandable last (2) for furnishing footwear (110) with an insert (100) includes an expansion assembly (40); an expandable shell (6), arranged around the expansion assembly (40); and a liquid chamber (8) within the expandable shell (6); wherein the expandable last (2) is insertable into the footwear (110) through a collar of the footwear (110) and wherein the expandable shell (6) is configured to expand for pressing the insert (100) towards an inside of the footwear (110); and wherein the expansion assembly (40) is configured to adapt its extension for exerting localized pressure onto the expandable shell (6) towards the inside of the footwear (110).

    Claims

    1. Expandable last (2) for furnishing footwear (110) with an insert (100), comprising: an expansion assembly (40); an expandable shell (6), arranged around the expansion assembly (40); and a liquid chamber (8) within the expandable shell (6); wherein the expandable last (2) is insertable into the footwear (110) through a collar of the footwear (110) and wherein the expandable shell (6) is configured to expand for pressing the insert (100) towards an inside of the footwear (110); and wherein the expansion assembly (40) is configured to adapt its extension for exerting localized pressure onto the expandable shell (6) towards the inside of the footwear (110).

    2. Expandable last (2) according to claim 1, wherein the expansion assembly (40) comprises at least one of a hydraulically operated piston, a pneumatically operated piston (46), an electrically operated piston, and a spring-loaded piston (44) for exerting the localized pressure.

    3. Expandable last (2) according to claim 2, wherein the expansion assembly (40) comprises a base plate (42), to which said at least one of a hydraulically operated piston, a pneumatically operated piston (46), an electrically operated piston, and a spring-loaded piston (44) is mounted.

    4. Expandable last (2) according to any of claims 1 to 3, wherein the expansion assembly (40) comprises a spring-loaded piston (44) for exerting the localized pressure, wherein the spring-loaded piston (44) comprises at least one of a coil spring and a gas spring.

    5. Expandable last (2) according to any of claims 1 to 4, wherein the expansion assembly (40) is configured to exert localized pressure onto at least one of a toe portion and a heel portion of the expandable shell (6).

    6. Expandable last (2) according to claim 1, wherein the expansion assembly (40) comprises a spring skeleton (55) having a forefoot spring portion (56), configured to exert localized pressure onto at least one of a toe portion and an instep portion of the expandable shell (6), and having a heel spring portion (57), configured to exert localized pressure onto a heel portion of the expandable shell (6).

    7. Expandable last (2) according to claim 6, wherein the forefoot spring portion (56) is configured to force its forefoot end portion in a forward and upward direction.

    8. Expandable last (2) according to claim 6 or 7, wherein the forefoot spring portion (56) has a waved shape, with a first exposed portion (56a) exerting localized pressure onto the instep portion of the expandable shell (6) and with a second exposed portion (56b) exerting localized pressure onto the toe portion of the expandable shell (6).

    9. Expandable last (2) according to claim 6 or 7, wherein the forefoot spring portion (56) comprises an instep spring element (58), extending along the instep portion of the expandable shell (6) and having its free end pointing rearwards.

    10. Expandable last (2) according to any of claims 6 to 9, wherein the heel spring portion (57) is configured to force its heel end portion in a rearward and upward direction.

    11. Expandable last (2) according to any of claims 6 to 10, wherein the expansion assembly (40) comprises a form-stable core support element (4), wherein the form-stable core support element (4) is in particular substantially L-shaped or substantially T-shaped.

    12. Expandable last (2) according to any of claims 1 to 11, further comprising a lid (10), to which the expandable shell (6) is mounted.

    13. Expandable last (2) according to claim 12, wherein the expansion assembly (40) is fixed in position with respect to the lid (10), in particular mounted to the lid (10) via a mounting rod (54).

    14. Expandable last (2) according to any of claims 1 to 13, wherein the expansion assembly (40) is attached to the expandable shell (6).

    15. Expandable last (2) according to any of claims 1 to 14, further comprising a liquid port (16), providing liquid communication between the liquid chamber (8) and an external liquid source (120), wherein the expandable shell (6) is configured to expand for pressing the insert (100) towards an inside of the footwear (110), when receiving liquid in the liquid chamber (8) via the liquid port (16).

    16. Expandable last (2) according to any of claims 1 to 14, further comprising a heater (60) arranged in the liquid chamber (8), wherein the heater (60) is configured to heat liquid in the liquid chamber (8) for expanding the expandable shell (6) and pressing the insert (100) towards an inside of the footwear (110) via an increase in volume of the liquid in the liquid chamber (8).

    17. Expandable last (2) according to claim 16, wherein the heater (60) is an electric heater.

    18. Expandable last (2) according to claim 16 or 17, wherein the expansion assembly (40) and the heater (60) are fixed in position with respect to each other, wherein the expansion assembly (40) and the heater (60) are in particular formed as an integrated structural unit.

    19. Expandable last (2) according to any of claims 16 to 18, further comprising a lid (10), to which the expandable shell (6) is mounted.

    20. Expandable last (2) according to claim 19, wherein the expandable shell (6) and the lid (10) form a liquid-tight enclosure.

    21. Expandable last (2) for furnishing footwear (110) with an insert (100), comprising: a form-stable core support element (4); an expandable shell (6), arranged around the core support element (4); a liquid chamber (8) within the expandable shell (6); and a liquid port (16), providing liquid communication between the liquid chamber (8) and an external liquid source (120); wherein the expandable last (2) is insertable into the footwear (110) through a collar of the footwear (110) and wherein, when receiving liquid in the liquid chamber (8) via the liquid port (16), the expandable shell (6) is configured to expand for pressing the insert (100) towards an inside of the footwear (110).

    22. Expandable last (2) according to claim 21, wherein the core support element (4) is substantially L-shaped or substantially T-shaped or substantially U-shaped or substantially foot-shaped.

    23. Expandable last (2) according to claim 21 or 22, wherein the core support element (4) is rigid, in particular made from metal or rigid plastics material.

    24. Expandable last (2) according to claim 21 or 22, wherein the core support element (4) is flexible, in particular made from resilient rubber material.

    25. Expandable last (2) according to any of claims 21 to 24, wherein the liquid chamber (8) comprises substantially the entire volume between the core support element (4) and the expandable shell (6).

    26. Expandable last (2) according to any of claims 21 to 25, wherein the core support element (4) comprises at least one liquid supply line (20), coupled to the liquid port (16) and providing liquid communication between the liquid port (16) and the liquid chamber (8).

    27. Expandable last (2) according to claim 26, wherein the at least one liquid supply line (20) is arranged within the core support element (4) and has at least one opening (22) towards the liquid chamber (8).

    28. Expandable last (2) according to any of claims 21 to 27, wherein the expandable shell (6) is elastic, in particular made from latex material.

    29. Expandable last (2) according to any of claims 21 to 28, wherein the expandable shell (6) has, at least in one or more regions thereof, dimension-specific elastic properties.

    30. Expandable last (2) according to any of claims 21 to 29, wherein the liquid chamber (8) is at least partly filled with an open-cell foam (24), in particular with an open-cell polyurethane foam, and/or with a spacer fabric.

    31. Expandable last (2) according to any of claims 21 to 30, further comprising at least one expandable liquid bag (26), arranged outside or inside of the expandable shell (6).

    32. Expandable last (2) according to claim 31, further comprising at least one ancillary liquid port (28), providing liquid communication between the at least one expandable liquid bag (26) and at least one external liquid source.

    33. Expandable last (2) according to claim 32, further comprising at least one ancillary liquid supply line (30), coupling the at least one expandable liquid bag (26) to the at least one ancillary liquid port (28), wherein the at least one ancillary liquid supply line (30) in particular runs through the liquid chamber (8).

    34. Expandable last (2) according to any of claims 31 to 33, wherein the at least one expandable liquid bag (26) comprises at least one of: an expandable liquid bag at an instep portion of the expandable shell (6); an expandable liquid bag at a toe portion of the expandable shell (6); an expandable liquid bag in a forefoot portion of the expandable shell (6); an expandable liquid bag in an upper midfoot portion of the expandable shell (6).

    35. Expandable last (2) according to any of claims 31 to 34, wherein the at least one expandable liquid bag (26) is at least partly filled with an open-cell foam, in particular with an open-cell polyurethane foam, and/or with a spacer fabric (34).

    36. Expandable last (2) according to any of claims 21 to 35, further comprising a lid (10), to which the core support element (4) and the expandable shell (6) are mounted.

    37. Expandable last (2) according to claim 36, wherein the liquid port (16) is arranged in the lid (10).

    38. Expandable last (2) according to claim 36 or 37, wherein the lid (10) has an extension substantially corresponding to a transverse cross-section of the collar of the footwear (110).

    39. Expandable last (2) according to any of claims 21 to 38, further comprising a heater, configured to heat the liquid in the liquid chamber (8) and/or to heat the expandable shell (6).

    40. Expandable last (2) according to any of claims 21 to 39, configured for furnishing the footwear with a waterproof, breathable bootie, the waterproof, breathable bootie in particular being provided, on its outside, with pressure sensitive adhesive and/or heat-activated adhesive for attachment to the inside of the footwear.

    41. Expandable last (2) for furnishing footwear (110) with an insert (100), comprising: an expandable shell (6); a liquid chamber (8) within the expandable shell (6); and a liquid port (16), providing liquid communication between the liquid chamber (8) and an external liquid source (120); wherein the expandable last (2) is insertable into the footwear (110) through a collar of the footwear (110) and wherein, when receiving liquid in the liquid chamber (8) via the liquid port (16), the expandable shell (6) is configured to expand for pressing the insert (100) towards an inside of the footwear (110); and wherein the expandable shell (6) has, at least in one or more regions thereof, dimension-specific elastic properties.

    42. Expandable last (2) according to claim 41, wherein the expandable shell (6) is configured to expand more easily in a longitudinal dimension (72) than in a circumferential dimension (74) in at least one of a midfoot portion (70) and a forefoot portion.

    43. Expandable last (2) according to claim 41 or 42, wherein the expandable last (2) is free of a form-stable core support element and/or free of an expansion assembly, arranged within the expandable shell.

    44. Expandable last (2) for furnishing footwear (110) with an insert (100), comprising: a rigid last portion (80, 82); an expandable shell (6), arranged adjacent to the rigid last portion (80, 82); a liquid chamber (8) within the expandable shell (6); and a liquid port (16), providing liquid communication between the liquid chamber (8) and an external liquid source (120); wherein the expandable last (2) is insertable into the footwear (110) through a collar of the footwear (110) and wherein, when receiving liquid in the liquid chamber (8) via the liquid port (16), the expandable shell (6) is configured to expand for pressing the insert (100) towards an inside of the footwear (110).

    45. Expandable last (2) according to claim 44, wherein the rigid last portion (80, 82) is made from metal, such as aluminum.

    46. Expandable last (2) according to claim 44 or 45, wherein the rigid last portion (80, 82) is heatable.

    47. Expandable last (2) according to any of claims 44 to 46, comprising a rigid forefoot and instep last portion (80) and a rigid heel last portion (82), wherein the expandable shell (6) is arranged between the rigid forefoot and instep last portion (80) and the rigid heel last portion (82).

    48. Expandable last (2) according to claim 47, wherein the rigid forefoot and instep last portion (80) and the rigid heel last portion (82) are movable with respect to each other and wherein the expandable last comprises an actuator (84) for controlling a spacing between the rigid forefoot and instep last portion (80) and the rigid heel last portion (82), with the actuator (84) in particular being a pneumatic or hydraulic or electric actuator.

    49. Expandable last (2) according to any of claims 44 to 48, further comprising at least one expandable liquid bag (26), arranged on an outside of the rigid last portion (80, 82).

    50. Expandable last (2) according to claim 49, wherein the at least one expandable liquid bag (26) comprises at least one expandable liquid bag in a toe region and/or in a heel region of the expandable last (2), in particular an expandable liquid bag in a toe region of the rigid forefoot and instep last portion (80).

    51. Expandable last (2) for furnishing footwear (110) with an insert (100), comprising: an expandable shell (6); a granulate chamber (61) within the expandable shell (6); and a granulate port (62), providing a granulate channel between the granulate chamber (61) and an external granulate source (64), in particular between the granulate chamber (61) and an external heated granulate source (64); wherein the expandable last (2) is insertable into the footwear (110) through a collar of the footwear (110) and wherein, when receiving granulate (63) in the granulate chamber (61) via the granulate port (62), the expandable shell (6) is configured to expand for pressing the insert (100) towards an inside of the footwear (110).

    52. Method for furnishing footwear (110) with an insert (100) using an expandable last (2) according to any of the preceding claims.

    53. Method according to claim 52, wherein the insert (100) is a waterproof, breathable bootie.

    54. Method for furnishing footwear (110) with an insert (100), the method comprising: inserting an expandable last (2) into the footwear (110) through a collar of the footwear (110), the expandable last (2) having an expandable shell (6) and a liquid chamber (8) within the expandable shell; and pressing the insert (100) towards an inside of the footwear (110) by expanding the expandable shell (6) via liquid in the liquid chamber (8).

    55. Method according to claim 54, wherein said expanding of the expandable shell (6) via liquid in the liquid chamber (8) comprises introducing liquid into the liquid chamber (8).

    56. Method according to claim 54 or 55, wherein said expanding of the expandable shell (6) via liquid in the liquid chamber (8) comprises heating the liquid in the liquid chamber (8).

    57. Method according to any of claims 54 to 56, wherein the insert (100) is a waterproof, breathable bootie.

    Description

    [0144] Further exemplary embodiments of the invention will be described below with reference to the accompanying drawings, wherein:

    [0145] FIG. 1 shows an expandable last in accordance with a first exemplary embodiment of the invention in a longitudinal cross-sectional view;

    [0146] FIG. 2 shows an expandable last in accordance with a second exemplary embodiment of the invention in a longitudinal cross-sectional view;

    [0147] FIG. 3 shows an expandable last in accordance with a third exemplary embodiment of the invention in a longitudinal cross-sectional view;

    [0148] FIG. 4A shows an expandable last in accordance with a fourth exemplary embodiment of the invention in a longitudinal cross-sectional view, and FIG. 4B shows a modification thereof in a longitudinal cross-sectional view;

    [0149] FIG. 5 shows an expandable last in accordance with a fifth exemplary embodiment of the invention in a longitudinal cross-sectional view;

    [0150] FIG. 6 shows an expandable last in accordance with a sixth exemplary embodiment of the invention in a longitudinal cross-sectional view;

    [0151] FIG. 7 shows an expandable last in accordance with a seventh exemplary embodiment of the invention in a longitudinal cross-sectional view;

    [0152] FIG. 8 shows an expandable last in accordance with an eight exemplary embodiment of the invention in a longitudinal cross-sectional view;

    [0153] FIG. 9 shows an expandable last in accordance with a ninth exemplary embodiment of the invention in a longitudinal cross-sectional view;

    [0154] FIG. 10 illustrates a method for furnishing footwear with an insert in accordance with an exemplary embodiment of the invention, the method using an expandable last according to an exemplary embodiment of the invention;

    [0155] FIG. 11 shows an expandable last in accordance with a tenth exemplary embodiment of the invention in a longitudinal cross-sectional view;

    [0156] FIG. 12 shows an expandable last in accordance with an eleventh exemplary embodiment of the invention in a longitudinal cross-sectional view; and

    [0157] FIG. 13 shows an expandable last in accordance with a twelfth exemplary embodiment of the invention in a longitudinal cross-sectional view.

    [0158] FIG. 1 shows an expandable last 2 in accordance with a first exemplary embodiment of the invention in a schematic longitudinal cross-sectional view. When imagining the expandable last 2 arranged in the interior of a footwear and the footwear being placed on a table or other horizontal structure in its normal use position, the cross-sectional view of FIG. 1 is a vertical cross-sectional view, with the cross-sectional plane running substantially through the center of the expandable last in the transverse direction of the footwear. The expandable last 2 may be used both for a left shoe and a right shoe. However, it is also possible that different versions of the expandable last are used for the left shoe and the right shoe.

    [0159] The expandable last 2 comprises a form-stable core support element 4. In the exemplary embodiment of FIG. 1, the core support element 4 is substantially foot-shaped. This means that the core support element 4 roughly resembles a human foot, having an ankle portion, a heel portion, a midfoot portion and a forefoot portion. In the exemplary embodiment of FIG. 1, the core support element is flexible, made from rubber material. This means that the core support element 4 has some flexibility, which is particularly useful for inserting the expandable last into the interior of a footwear. In the exemplary embodiment of FIG. 1, the core support element 4 is made from resilient rubber material, with the resilience of the rubber material counter-acting a deformation and maintaining the foot shape within the footwear. The core support element 4 is considered form-stable, as it does not have any active shape adjusting means. Also, its resilience aims as maintaining the foot shape. Further, while providing some flexibility, the rubber material of the core support element is sufficiently rigid for the expandable last to not completely loose its shape/undergo a substantial shape transformation during insertion into the footwear.

    [0160] The expandable last 2 further comprises an expandable shell 6. The expandable shell 6 is arranged around the core support element 4. Between the core support element 4 and the expandable shell 6, a liquid chamber 8 is formed. The expandable shell 6 is made from, for example, a latex material and forms the outermost part of the expandable last 2 for a large portion thereof. In particular, the expandable shell 6 forms the outermost portion of the expandable last 2 in the heel portion, the midfoot portion, the forefoot portion, and part of the ankle portion of the expandable last 2. The expandable shell 6 is elastic and can expand upon receiving liquid in the liquid chamber 8.

    [0161] In the exemplary embodiment of FIG. 1, the expandable shell 6 is liquid-tight/liquid-proof. Upon receiving liquid, such as water, the expandable shell 6 contains the liquid in the liquid chamber 8 and expands as a response to an increasing amount of liquid. The latex material of the expandable shell 6 is inherently liquid-proof, also in an expanded/stretched state. The expandable shell 6 may have one latex layer. It may also be made of a two-layer or three-layer structure, in particular a two-layer latex structure or a three-layer latex structure.

    [0162] The expandable last 2 further comprises a lid 10. The form-stable core support element 4 and the expandable shell 6 are mounted to the lid 10. Together, the expandable shell 6 and the lid 10 fully enclose the core support element 4 and the liquid chamber 8.

    [0163] The lid 10 is a substantially rotationally symmetric structure, having an inner lid portion 12 and an outer lid portion 14. The lid 10 may be made from plastic or other suitable material. The expandable shell 6 is clamped between the inner lid portion 12 and the outer lid portion 14 in a liquid-tight manner. For additional sealing, a suitable sealing tape, such as a vulcanization tape, may be applied. In this way, no liquid can escape from the liquid chamber 8 through the expandable shell 6 or through its connection to the lid 10. The lid 10 has a transverse cross-sectional extension that substantially corresponds to the transverse extension of the collar of a footwear. In particular, the transverse extension of the lid 10 may correspond to the transverse extension of the collar of the footwear at or above an ankle portion thereof.

    [0164] The expandable last 2 further comprises a liquid port 16. In the exemplary embodiment of FIG. 1, the liquid port 16 is part of the lid 10. In particular, the liquid port 16 is a duct through the inner lid portion 12. In the exemplary embodiment of FIG. 1, the liquid port 16 is equipped with a valve 18, which allows for liquid to be pressured into the expandable last 2 from an external liquid source and which prevents liquid from flowing back out of the expandable last 2. While generally preventing liquid from flowing out of the liquid chamber 8, the valve 18 may be manipulated in such a manner that the liquid can be evacuated from the liquid chamber 8.

    [0165] The core support element 4 comprises a liquid supply line system 20 that is coupled to the liquid port 16. Liquid from the external liquid source may enter the liquid supply line system 20 via the liquid port 16. In the exemplary embodiment of FIG. 1, the liquid supply line system 20 has a substantially vertical liquid supply line, running downwards from the liquid port 16, and a substantially horizontal liquid supply line, running from a sole-side end of the substantially vertical liquid supply line both towards a heel portion of the core support element 4 and a forefoot portion of the core support element 4. The substantially horizontal liquid supply line has two openings 22 towards the liquid chamber 8. In particular, the substantially horizontal liquid supply line has an opening 22 towards a heel portion of the liquid chamber 8 and an opening towards a forefoot portion of the liquid chamber 8. In this way, the core support element 4 and its liquid supply line system are well-suited to distribute the liquid, received by the liquid port 16, within the liquid chamber 8.

    [0166] In use, an insert may be arranged around the expandable shell 6, the expandable last 2 and the insert may be jointly introduced into a footwear, an external liquid source may be coupled to the liquid port 16, liquid, in particular heated liquid may be introduced into the liquid chamber 8 via the liquid port 16 and the liquid supply line system 20, the expandable shell 6 may expand as a response to an increasing amount of liquid in the liquid chamber 8, and the insert may be pressed against the inside of the footwear. A more detailed description of the provision of an insert on the inside of the footwear is given below in FIG. 10. It is pointed out that said method steps are exemplary only and that other ways of furnishing footwear with an insert may be implemented with an expandable last in accordance with exemplary embodiments. For example, it is also possible to place an insert into the footwear, to fix an upper portion of the insert to a collar region of the footwear, and to then introduce the expandable last into the joint structure of footwear and insert. When introducing the expandable last into the insert, a cover may be placed over the last to protect the insert and/or the expandable shell from puncturing and to facilitate a smooth insertion of the expandable last into the insert. The cover may be a sock-like structure, in particular a textile sock-like structure. The introduction of liquid and the ensuing steps may then be carried out as described above. It is pointed out that the cover may also be placed over the expandable last as an intermediate element between the expandable last and the insert, when the expandable last is used for introducing the insert into the footwear. In this case, the cover may allow for a smoother pulling of the insert over the expandable last.

    [0167] FIG. 2 shows an expandable last 2 in accordance with a second exemplary embodiment of the invention in a schematic longitudinal cross-sectional view. Various components of the expandable last 2 of FIG. 2 are identical/similar to the corresponding components of the expandable last 2 of FIG. 1. They are provided with corresponding reference numerals, and reference is made to their description above. The two main differences between the expandable last 2 of FIG. 2 and the expandable last 2 of FIG. 1 are the design of the core support element 4 and the provision of an open-cell foam 24 in the liquid chamber 8. These differences will be discussed in detail below.

    [0168] The core support element 4 of the expandable last 2 of FIG. 2 is substantially L-shaped. The two legs of the L-shaped core support element 4 are a substantially vertical leg, running from the lid 10 in the direction of the sole of the expandable last 2, and a substantially horizontal leg, running from a sole-side end of the substantially vertical leg towards a forefoot portion of the expandable last 2. The L-shaped core support element is a stiff structure, made from metal or rigid plastics material.

    [0169] The liquid supply line system 20 of the core support element 4 of FIG. 2 has various branches. In particular, six openings 22 connect the liquid supply line system with the liquid chamber 8. Two of said openings 22 are provided in an ankle portion of the expandable last 2, one is provided in the heel portion of the expandable last 2, two are provided in the midfoot portion of the expandable last 2, and one is provided in the forefoot portion of the expandable last 2. A smaller or greater number of openings and branches, providing liquid paths to said openings, are possible as well.

    [0170] An open-cell foam 24 is arranged around the core support element 4 in the liquid chamber 8. The open-cell foam 24 is a flexible and soft structure that allows for the absorption and passage of liquid. In this way, the open-cell foam may on the one hand absorb liquid and on the other hand pass liquid on towards the expandable shell 6. In the exemplary embodiment of FIG. 2, the open-cell foam is provided in a large portion of the liquid chamber 8. The core support element 4 forms a core/skeleton, around which the open-cell foam 24 is arranged. The open-cell foam 24 provides an initial shape to the expandable shell 6, while allowing for an adaptation of the shape upon receiving liquid in the liquid chamber 8.

    [0171] FIG. 3 shows an expandable last 2 in accordance with a third exemplary embodiment of the invention in a schematic longitudinal cross-sectional view. Various components of the expandable last 2 of FIG. 3 are identical/similar to the components of the expandable lasts discussed above. They are provided with corresponding reference numerals, and reference is made to their description above.

    [0172] In the exemplary embodiment of FIG. 3, the core support element 4 is substantially T-shaped, having a substantially vertical leg and a substantially horizontal cross-bar/cross plate, extending from the substantially vertical leg both towards the heel portion of the expandable last 2 and towards the forefoot portion of the expandable last 2. It is also possible that the core support element has two substantially vertical legs and a substantially horizontal cross bar/cross plate, attached to both substantially vertical legs. In this case, the core support element would be substantially U-shaped, in particular in the form of an upside down U. In the exemplary embodiment of FIG. 3, the core support element 4 is free of a liquid supply line system. Instead, the liquid port 16 is directly coupled to the liquid chamber 8. Liquid from the external liquid source is directly supplied to the liquid chamber 8, without flowing through the core support element 4.

    [0173] The expandable last 2 of FIG. 3 further comprises an expandable liquid bag 26, arranged on the outside of the expandable shell 6 at an instep portion of the expandable shell 6. The expandable last 2 of FIG. 3 further comprises an ancillary liquid port 28, which is coupled to the expandable liquid bag 26 via an ancillary liquid supply line 30. The ancillary liquid port 28 is equipped with a valve 32. The ancillary liquid supply line 30 runs through the interior of the expandable shell 6, i.e. through the liquid chamber 8. Alternatively, the ancillary liquid supply line may run along the outside of the expandable shell 6. The ancillary liquid supply line 30 may be a flexible liquid supply line, such as a rubber hose type liquid line.

    [0174] The expandable liquid bag 26 is made from elastic material, such as from latex material, and may expand upon receiving liquid via the ancillary liquid port 28 and the ancillary liquid supply line 30. The liquid port 16 and the ancillary liquid port 28 allow for controlling the pressure in the liquid chamber 8 and the pressure in the expandable liquid bag 26 to differ from each other, such that controlled pressure differences between the instep portion of the expandable last 2 and the remainder of the expandable last 2 may be achieved. The liquid port 16 and the ancillary liquid port 28 may be coupled to different external liquid sources. In addition/alternatively, other means for achieving a desired pressure differential between the liquid chamber 8 and the expandable liquid bag 26, such as different valves in the liquid port 16 and the ancillary liquid port 28, may also be provided.

    [0175] In the exemplary embodiment of FIG. 3, a spacer fabric 34 is arranged in the expandable liquid bag 26. The spacer fabric 34 may provide for an initial shape of the expandable liquid bag 26, while allowing liquid to pass therethrough and distributing within the expandable liquid bag 26.

    [0176] FIG. 4A shows an expandable last 2 in accordance with a fourth exemplary embodiment of the invention in a schematic longitudinal cross-sectional view. Various components of the expandable last 2 of FIG. 4A are identical/similar to the components of the expandable lasts discussed above. They are provided with corresponding reference numerals, and reference is made to their description above.

    [0177] The expandable last 2 of FIG. 4A is somewhat similar to the expandable last of FIG. 1. The expandable last 2 of FIG. 4A also comprises a substantially foot-shaped, form-stable core support element 4. The core support element 4 is somewhat shorter in a forefoot portion of the expandable shell and has a substantially flat front end portion. Instead of an opening towards the front of the core support element, the liquid supply line system 20 of the core support element 4 of FIG. 4A has transverse openings 22 close to its front end, as indicated by a circle in FIG. 4A.

    [0178] The expandable last 2 of FIG. 4A further comprises an expandable liquid bag 26, arranged within the expandable shell 6 and arranged between the front end of the core support element 4 and the toe end of the expandable shell 6. In particular, the expandable liquid bag is arranged to abut the front end of the core support element 4. The expandable liquid bag 26 is in liquid communication with an ancillary liquid port 28 via an ancillary liquid supply line 30. In the exemplary embodiment of FIG. 4A, the ancillary liquid supply line 30 at least partly runs through the core support element 4. The expandable liquid bag 26 is arranged and configured to expand upon receiving liquid from an external liquid source via the ancillary liquid port 28 and the ancillary liquid supply line 30. Further, the expandable liquid bag 26 is arranged and configured to expand towards the front of the expandable last, i.e. towards the front of the expandable shell 6, as indicated in broken lines in FIG. 4A. In particular, the expandable liquid bag 26 may expand to abut the expandable shell 6 in operation. In this way, the expandable liquid bag 26 may exert pressure onto the toe portion of the insert in a particularly targeted manner. The liquid in the expandable liquid bag 26 may exert pressure onto the toe portion in a highly reliable manner and cannot evade the toe region, irrespective of the overall circumstances within the footwear. The pressure within the expandable liquid bag 26 may be chosen to be the same or similar to the pressure within the liquid chamber 8 in operation. It is also possible that the pressure within the expandable liquid bag 26 is greater than the pressure within the liquid chamber 8.

    [0179] FIG. 4B shows an expandable last 2 in accordance with a modification of the expandable last 2 of FIG. 4A. The expandable last 2 of FIG. 4B is also in accordance with an exemplary embodiment of the invention and is also depicted in a schematic longitudinal cross-sectional view.

    [0180] In the exemplary embodiment of FIG. 4B, the core support element 4 and the expandable liquid bag 26 in the forefoot portion of the expandable shell 6 do not abut along a flat surface, but along a contoured surface. In particular, the core support element 4 extends further to the front of the expandable last 2 in an upper portion thereof, as compared to a lower portion thereof. In this way, the expandable liquid bag is restrained from expanding towards the top, at least to some extent, and an expansion towards the front of the expandable shell 6 is promoted.

    [0181] Further, a directing element 36, such as a knitted fabric, is provided on the sole side of a front portion of the core support element 4 and on the sole side of the expandable liquid bag 26. The directing element 36 may have the double purpose of holding the sole side of the expandable liquid bag 26 in position with respect to the core support element 4 and of preventing the expandable liquid bag 26 to expand towards the sole side of the expandable shell 6. The contoured engagement surface between the core support element 4 and the expandable liquid bag 26 and the directing element 36 may cooperate to promote the expansion of the expandable liquid bag 26 towards the front of the expandable last 2. The expandable liquid bag 26 may be molded or welded to the core support element 4 or may be attached thereto in any other suitable manner. Also, the directing element 36 may be molded or welded to the core support element 4 and/or to the expandable liquid bag 26. It is also possible that the directing element 36 may be integrated with the expandable liquid bag 26 and/or the core support element 4. For example, the expandable liquid bag 26 and/or the core support element may be molded onto the directing element 36. In that case, the directing element may be partly or fully arranged in the expandable liquid bag 26 and/or the core support element. The directing element 36 may for example be made from PE, PES, or PA.

    [0182] The expandable liquid bag 26 in the forefoot portion of the expandable shell 6 may be made from any suitable material that is expandable and that can be coupled to the directing element 36. The expandable liquid bag 26 in the forefoot portion of the expandable shell 6 may be made from a bladder structure that has an inherent 3D shape. The expandable liquid bag may for example be made from latex or thermoplastic or adherable plastic compounds, such as Butyl.

    [0183] Yet further, the expandable last comprises an expandable liquid bag 26 in an upper midfoot portion of the expandable shell 6. The expandable liquid bag 26 is coupled to an external liquid source via a further ancillary liquid port 28 and a further ancillary liquid supply line 30. The expandable liquid bag 26 in the upper midfoot portion of the expandable shell 6 may be partly or entirely filled with a spacer fabric or may be not filled with a spacer fabric. The expandable liquid bag 26 in the upper midfoot portion of the expandable shell 6 contributes to the exertion of suitable pressure onto an instep portion of the insert via the instep portion of the expandable shell 6.

    [0184] FIG. 5 shows an expandable last 2 in accordance with a fifth exemplary embodiment of the invention in a schematic longitudinal cross-sectional view. Various components of the expandable last 2 of FIG. 5 are identical/similar to the components of the expandable lasts discussed above. They are provided with corresponding reference numerals, and reference is made to their description above.

    [0185] As compared to the expandable lasts of FIGS. 1 to 4, the expandable last 2 of FIG. has an expansion assembly 40, which will be described in detail below. In the exemplary embodiment of FIG. 5, the liquid port 16 is directly coupled to the liquid chamber 8, such that the liquid from the external liquid source is directly supplied into the liquid chamber 8.

    [0186] The expansion assembly 40 comprises a base plate 42 and a spring-loaded piston 44. The base plate 42 is oriented substantially horizontally and is arranged on the inside of the expandable shell 6 at a sole portion thereof. In the exemplary embodiment of FIG. 5, the base plate 42 extends over about 50% of the sole area of the expandable last 2. The spring-loaded piston 44 is attached to the base plate 42 and is also oriented substantially horizontally. The spring-loaded piston is arranged to stretch the expandable shell 6 in a longitudinal direction of the expandable last 2 and to exert localized pressure onto the expandable shell 6 in a heel portion and toe portion of the expandable last 2. With the localized pressure stemming from the spring of the spring-loaded piston 44, no active means, i.e. no means relying on an external supply of energy, are required for exerting the localized pressure. The localized pressure is solely generated by the spring of the spring-loaded piston 44, acting against its compression.

    [0187] The expansion assembly 40 further comprises a mounting rod 54, which is coupled to the lid 10. Via the mounting rod 54, the expansion assembly 40 is fixed in position with respect to the lid 10. An overall stable arrangement may be achieved, and the expansion assembly may provide core support to the expandable last 2, similar to the core support element 4 described above.

    [0188] The expandable last 2 of FIG. 5 allows for providing localized pressure at selected portions of the expandable last 2, while providing a more uniform all around pressure via the liquid in the liquid chamber 8. In this way, different pressure levels and/or a dynamic application of different pressures at different times may be achieved in an effective manner.

    [0189] FIG. 6 shows an expandable last 2 in accordance with a sixth exemplary embodiment of the invention in a schematic longitudinal cross-sectional view. Various components of the expandable last 2 of FIG. 6 are identical/similar to the components of the expandable lasts discussed above. They are provided with corresponding reference numerals, and reference is made to their description above.

    [0190] The expandable last 2 of FIG. 6 is somewhat similar to the expandable last 2 of FIG. 5. However, the expansion assembly 40 differs considerably from the expansion assembly 40 from FIG. 5. In particular, instead of the spring-loaded piston 44, an active piston 46 is provided. In the exemplary embodiment of FIG. 6, the active piston 46 is a pneumatically operated piston 46. Similar to the spring-loaded piston 44 of FIG. 5, the pneumatically operated piston 46 exerts localized pressure onto the heel portion and the toe portion of the expandable shell 6.

    [0191] The expansion assembly 40 comprises a pneumatic port 48 in the lid 10 and a pneumatic line 50, connecting the pneumatic port 48 and the pneumatically operated piston 46. The pneumatic port 48 has a valve 52. In operation, the extension of the pneumatically operated piston 46 can be controlled via the pneumatic pressure therein, which in turn may be controlled via an external gas source, such as an external air source, coupled to the pneumatic port 48. In this way, the exertion of localized pressure can be controlled with a high degree of granularity.

    [0192] The expansion assembly 40 of FIG. 6 also comprises a mounting rod 54. Via the mounting rod 54, the base plate 42 and the pneumatically operated piston 46 are fixed in position with respect to the lid 10. In this way, the expansion assembly 40 has high positional stability within the expandable last 2, and the expandable last 2 can be handled conveniently as an overall highly stable structure.

    [0193] FIG. 7 shows an expandable last 2 in accordance with a seventh exemplary embodiment of the invention in a schematic longitudinal cross-sectional view. Various components of the expandable last 2 of FIG. 7 are identical/similar to the components of the expandable lasts discussed above. They are provided with corresponding reference numerals, and reference is made to their description above.

    [0194] The expandable last 2 of FIG. 7 is somewhat similar to the expandable last 2 of FIG. 5, albeit with some significant differences. The expandable last 2 of FIG. 7 also has an expansion assembly 40, which comprises a base plate 42 and a spring-loaded piston 44. The expansion assembly 40 further comprises a mounting rod 54, which is mounted to the lid 10 and to which the base plate 42 is mounted. The spring-loaded piston 44 is in turn mounted to the base plate 42. In this way, the spring-loaded piston 44, the base plate 42, the mounting rod 54, and the lid 10 are fixed in position with respect to each other. In this arrangement, the spring-loaded piston 44 exerts localized pressure onto the expandable shell 6 at a single portion thereof. In the exemplary embodiment of FIG. 7, the spring-loaded piston 44 exerts localized pressure onto the toe portion of the expandable shell 6.

    [0195] The expandable last 2 of FIG. 7 further comprises a heater 60. In the exemplary embodiment of FIG. 7, the heater 60 is embodied as an electric heater. In particular, the heater is embodied as a heating coil that is wound around the mounting rod 54. The heater 60 is coupled to a power supply cable 62 that runs through the lid 16 and that may be coupled to an external power source, such as a power adapter that is in turn connectable to a standard power outlet. Via the heater, the liquid in the liquid chamber 8 may be heated and expanded. The expansion of the liquid may be used for the expansion of the expandable shell 6. In this way, in addition to the localized pressure exerted by the expansion assembly 40, a highly uniform pressure may be generated all around the expandable shell 6.

    [0196] In the exemplary embodiment of FIG. 7, both the lid 10 as well as the expandable shell 6 are free of a liquid port. When being arranged within the footwear and exerting pressure onto the insert towards the inside of the footwear, no liquid is added or evacuated from the liquid chamber 8. The heating of the liquid within the liquid chamber 8 provides for the all around exertion of pressure onto the insert. It is pointed out that any suitable liquid may be used for achieving the expansion of the expandable shell 6. For example, the liquid chamber 8 may be filled with water, and the expansion of the water upon heating may provide for the desired increase in pressure.

    [0197] It is pointed out that, instead of/in addition to a heater being provided in the liquid chamber 8, the expandable last may be placed into a heating device, such as an electric oven or a microwave oven, and may then be inserted into the footwear. This heating may also achieve the expansion of the liquid in the liquid chamber 8, and the exertion of pressure onto the insert via the expandable shell 6 may take place via the heated liquid.

    [0198] FIG. 8 shows an expandable last 2 in accordance with an eighth exemplary embodiment of the invention in a schematic longitudinal cross-sectional view. Various components of the expandable last 2 of FIG. 8 are identical/similar to the components of the expandable lasts discussed above. They are provided with corresponding reference numerals, and reference is made to their description above.

    [0199] The expandable last 2 of FIG. 8 is somewhat similar to the expandable last 2 of FIG. 5, albeit with some significant differences. The expandable last 2 of FIG. 8 does not have a core support element nor an expansion assembly nor a heater, as described with respect to FIGS. 1 to 7. However, the expandable last 2 of FIG. 8 has a liquid port 16, running through the lid 10, for inserting liquid into the liquid chamber 8. The expandable shell 6 expands solely in response to the introduction of liquid into the liquid chamber 8.

    [0200] The expandable shell 6 has dimension-specific elastic properties. In the exemplary embodiment of FIG. 8, a midfoot portion 70 of the expandable shell 6 has dimension-specific elastic properties. It is possible that other portions of the expandable shell 6 have dimension-specific elastic properties as well.

    [0201] In particular, the midfoot portion 70 of the expandable shell 6 stretches in a longitudinal dimension 72 at a lower liquid pressure than in a circumferential dimension 74. In this context, the circumferential dimension 74 is defined as extending around the tube-like cross-section of the midfoot portion 70. With the expandable shell 6 thus expanding easier in the longitudinal dimension 72 than in the circumferential dimension 74 in the midfoot portion 70, an increase in liquid pressure leads to an elongation of the midfoot portion 70 along the length of the expandable last 2, before a circumferential expansion and, thus, an increase in cross-section in the midfoot portion 70 takes place. In this way, the expandable last 2 may first adapt to a particular footwear size/length, before exerting a highly uniform all around pressure onto the insert against the inside of the footwear. In a particular exemplary embodiment, the length of the midfoot portion may extend by between 10% and 30%, in particular by about 20%, before the circumferential expansion takes place.

    [0202] FIG. 9 shows an expandable last 2 in accordance with a ninth exemplary embodiment of the invention in a schematic longitudinal cross-sectional view. Various components of the expandable last 2 of FIG. 9 are identical/similar to the components of the expandable lasts discussed above. They are provided with corresponding reference numerals, and reference is made to their description above.

    [0203] The expandable last 2 of FIG. 9 comprises a rigid forefoot and instep last portion 80 and a rigid heel last portion 82. The rigid forefoot and instep last portion 80 and the rigid heel last portion 82 are made from aluminum. Jointly, they form a split last, having a rigid front portion and rigid rear portion. Both the rigid forefoot and instep last portion 80 and the rigid heel last portion 82 are heatable. They are coupled with a front power supply line 81 and a read power supply line 83, respectively, via which internal heaters of the rigid forefoot and instep last portion 80 and the rigid heel last portion 82 may be provided with electric energy. The internal heaters may be induction heaters or may comprise heating cartridges or may comprise other suitable heating devices. It is also possible that the rigid forefoot and instep last portion 80 and the rigid heel last portion 82 are not heatable. They may still be thermally conductive, and the lines 81, 83 may be sensor lines, coupling temperature sensors within the rigid forefoot and instep last portion 80 and the rigid heel last portion 82 to a control unit.

    [0204] The rigid forefoot and instep last portion 80 and the rigid heel last portion 82 are movable with respect to each other. The expandable last 2 comprises a pneumatic actuator 84, which is configured to control a spacing between the rigid forefoot and instep last portion 80 and the rigid heel last portion 82. The expandable last 2 further comprises a first gas port 86, equipped with a valve 88, and a second gas port 90, equipped with a valve 92. The first gas port 86 and the second gas port 88 are coupled to the pneumatic actuator 84 via a first gas line 94 and a second gas line 96, respectively. The first gas port 86 and the second gas port 90 are configured to introduce gas into the pneumatic actuator 84 from an external gas source and to release gas from the pneumatic actuator 84, respectively. By an according control of the first gas port 86 and the second gas port 90, the pressure in the pneumatic actuator 84 and, thus, the spacing between the rigid forefoot and instep last portion 80 and the rigid heel last portion 82 may be controlled in a highly accurate manner. The split last may thus be adapted to different footwear sizes/lengths over a wide size/length range.

    [0205] The expandable last 2 further comprises an expandable shell 6, which has a liquid chamber 8 therein. The expandable last 2 further comprises a liquid port 16, having a valve 18, which is coupled to the liquid chamber 8 via a liquid supply line 20. In operation, liquid may be received in the liquid chamber 8, and the expandable shell 6 may exert a highly uniform pressure onto an insert on the inside of the footwear in those portions of the footwear that are between the rigid forefoot and instep last portion 80 and the rigid heel last portion 82.

    [0206] The expandable last 2 further comprises an expandable liquid bag 26, arranged around the toe portion of the rigid forefoot and instep last portion 80. The liquid chamber 8 and the expandable liquid bag 26 are coupled via an ancillary liquid supply line 30. The ancillary liquid supply line 30 extends through the rigid forefoot and instep last portion 80. With the expandable liquid bag 26, the pressure exerted onto the insert in a forefoot portion of the footwear may be made more uniform than with the rigid forefoot and instep last portion 80. The expandable liquid bag may balance out sharp contours of the inside of the footwear in the toe portion in a particularly effective manner.

    [0207] With the combination of the rigid forefoot and instep last portion 80 and the rigid heel last portion 82 on the one hand and the expandable shell 6 and the expandable liquid bag 26 on the other hand, a good compromise between using rigid, comparably straightforward to implement last portions and using expandable last portions, which are highly flexible and well-suited for applying a uniform pressure, may be achieved.

    [0208] FIG. 10 illustrates a method for furnishing footwear 110 with an insert 100 in accordance with an exemplary embodiment of the invention. The method makes use of an expandable last 2 in accordance with an exemplary embodiment of the invention. In the exemplary illustration of FIG. 10, the expandable last 2 corresponds to the expandable last 2 of FIG. 5. However, it is stressed that an expandable last in accordance with any of the embodiments, as described herein, may be used.

    [0209] FIG. 10A depicts the expandable last 2 and an insert 100. The insert 100 is arranged over the expandable last 2. The insert 100 is in a relaxed state, i.e. in a state unstretched by the expandable last 2. In the illustration of FIG. 10, the insert 100 is a waterproof, breathable bootie. Accordingly, the method illustrated in FIG. is a method for waterproofing footwear. The waterproof, breathable bootie may for example be embodied in accordance with any of the embodiments, as described in PCT/EP2017/068030 and/or PCT/EP2018/084179.

    [0210] The insert 100 comprises a first glue-covered area 102 around the toe portion of the insert 100, a second glue-covered area 104 around the heel portion of the insert 100, and a third glue-covered area 106 along the collar of the insert 100. In the exemplary embodiment of FIG. 10, all of the first glue-covered area 102, the second glue-covered area 104, and the third glue-covered area are provided with heat-activated adhesive. Instead of/in addition to the third glue-covered area 106, a textile tape, sewn to the insert 100 and provided with suitable adhesive, may be provided.

    [0211] FIG. 10B depicts the expandable last 2 and the insert 100 inserted into the interior of the footwear 110. In the illustrated embodiment of FIG. 10, the footwear 110 is a low shoe. When introducing the expandable last, the insert 100 is placed onto the sole portion of the interior of the footwear 110 and against the heel portion of the interior of the footwear 110. With the expandable last 2 being in an unexpanded state and the insert 100 being in a relaxed state, the insert 100 is spaced from the other portions of the inside of the footwear 110.

    [0212] FIG. 10C depicts the expandable last 2 with the spring-loaded piston 44 having a larger horizontal extension than in FIG. 10B. The change in extension is the result of the spring of the spring-loaded piston counter-acting its compression and exerting localized pressure onto the toe portion and the heel portion of the expandable shell 6. The change in extension may be triggered by a release mechanism. For example, the spring-loaded piston may have a release button, which may be operated/pushed by an operator. For example, the release button may be operated manually, either through the footwear 110, the insert 100 and the expandable shell 6 or through the expandable shell 6 only or via a suitable mechanism at the lid 10. It is also possible that the spring-loaded piston expands without a release mechanism. For example, the spring-loaded piston may continuously force its extension, when being inserted into the footwear, similar to a shoe tree. It is further possible that the introduction of liquid causes the spring-loaded piston to expand or that the change in extension is triggered in any other suitable manner.

    [0213] FIG. 10D depicts the expandable last 2 with an external liquid supply line 120 coupled to the liquid port 16 of the expandable last 2. Via the liquid port 16, water is introduced into the liquid chamber 8 of the expandable last 2. In the exemplary embodiment of FIG. 10, the water is introduced into the liquid chamber 8 with a temperature of between 60° C. and 98° C., in particular with a temperature of about 95° C. Also, water is introduced until a target liquid pressure is reached in the liquid chamber 8. The target liquid pressure may be between 0.1 bar and 2 bar, in particular about 0.2 bar. As a result, the insert 100 is pressed against the inside of the footwear 110. The water provides for a uniform pressure within the liquid chamber 8 and presses the insert 100 towards the inside of the footwear 110 in a highly uniform manner. The temperature of the water also activates the heat-activated adhesive in the first, second, and third glue-covered areas 102, 104, 106. It is understood that the temperature and pressure of the liquid may be selected, depending on the particular liquid used. Various types of heat-activated adhesives may be activated at temperatures between 60° C. and 200° C., and the liquid may be introduced at a temperature suitable for the adhesive in question. An example for a suitable adhesive is temperature re-activatable PU, such as Irotex from P. B. Fuller.

    [0214] FIG. 10E depicts the expandable last 2 with the external liquid supply line 120 decoupled from the liquid port 16.

    [0215] FIG. 10F additionally depicts a toe cap protector 130, put over the toe portion of the footwear 110. The toe cap protector 130 may be held in place by a rubber band, being wrapped around the heel of the footwear 110. In this way, a counter-pressure may be provided at the toe portion of the footwear 110 and the toe portion of the footwear 110 may be protected.

    [0216] FIG. 10G depicts the expandable last 2, the insert 100, the footwear 110, and the toe cap protector 130 loosely placed in a bag 138. The bag 138 in turn is placed in a pressure chamber 140. The pressure chamber 140 is coupled to a pressure line 142, through which pressurized air can flow into the pressure chamber 140.

    [0217] FIG. 10H depicts the situation, after pressurized air has flown into the pressure chamber 140. In the exemplary embodiment of FIG. 10, an air pressure of between 2 bar and 7 bar, in particular an air pressure of about 5.5 bar, is used for pressurizing the pressure chamber 142. The pressurized air presses the bag 138 against the footwear 110 and provides for a counter-pressure against the expandable last 2.

    [0218] The combination of water pressure in the expandable last 2, heat from the water in the expandable last 2, and air pressure in the pressure chamber 140 are a highly effective way for adhering the insert 100 to the inside of the footwear 110. A very stable attachment with a highly uniform adhesion across the first, second, and third glue-covered areas 102, 104, 106 may be achieved.

    [0219] FIG. 11 shows an expandable last 2 in accordance with a tenth exemplary embodiment of the invention of a schematic longitudinal cross-sectional view. Various components of the expandable last 2 of FIG. 11 are identical/similar to the components of the expandable lasts discussed above. They are provided with corresponding reference numerals, and reference is made to their description above.

    [0220] The expandable last 2 of FIG. 11 is somewhat similar to the expandable last 2 of FIG. 5. In particular, the expandable last 2 of FIG. 11 also has an expansion assembly and also has a liquid port 16 that is directly coupled to the liquid chamber 8. However, the expansion assembly 40 of the expandable last 2 of FIG. 11 is quite different from the expansion assembly 40 of the expandable last 2 of FIG. 5, as will be laid out below.

    [0221] The expansion assembly 40 of the expandable last 2 of FIG. 11 has a form-stable core support element 4. The core support element 4 is substantially T-shaped. In particular, the core support element 4 has the design of the core support element 4 described above with respect to FIG. 3. Instead of being viewed as a T-shaped core support element, the core support element 4 may also be seen as the combination of a base plate and a mounting rod, attaching the base plate to the lid 10, as described above with respect to FIG. 5. The properties described above with respect to various embodiments of the core support element and described above with respect to various embodiments of the combination of the base plate and the mounting rod may be implemented in the framework of the expansion assembly of the expandable last 2 of FIG. 11 in an analogous manner.

    [0222] In the exemplary embodiment of FIG. 11, the expansion assembly 40 comprises a spring skeleton 55. The spring skeleton 55 is fixed to the lid 10 and extends towards a forefoot portion of the expandable last 2 and towards a heel portion of the expandable last 2 from the lid 10. In particular, the spring skeleton 55 has a forefoot spring portion 56 and a heel spring portion 57. Both the forefoot spring portion 56 and the heel spring portion 57 are configured to exert localized pressure onto the expandable shell 6 of the expandable last 2.

    [0223] The forefoot spring portion 56 has a waved shape. In particular, the forefoot spring portion 56 has a first exposed portion 56a and a second exposed portion 56b. The first exposed portion 56a is located at an instep portion of the expandable last 2. The second exposed portion 56b is located at a toe portion of the expandable last 2. The first and second exposed portion 56a, 56b may be thought of as high portions of the waved shape of the forefoot spring portion 56, when fitting a straight line through the waved shape of the forefoot spring portion 56.

    [0224] The forefoot spring portion 56 further comprises a pressure exertion pad 56c. The pressure exertion pad 56c is arranged at the forefoot end portion of the forefoot spring portion 56.

    [0225] The heel spring portion 57 extends from the lid 10 towards a heel portion of the expandable last 2. The heel spring portion 57 has a pressure exertion pad 57a at the heel end portion of the heel spring portion 57.

    [0226] The forefoot spring portion 56 and the heel spring portion 57 are of a metal strip design. In the longitudinal direction of the expandable last 2, the forefoot spring portion 56 has the described waved shape from the lid 10 to the toe portion of the expandable last 2, and the heel spring portion 57 has the depicted curved shape from the lid 10 to the heel portion of the expandable last 2. In the transverse direction of the expandable last 2, i.e. in the direction orthogonal to the viewing plane of FIG. 11, both the forefoot spring portion 56 and the heel spring portion 57 have a substantially constant width, thus forming a metal strip between the toe portion of the expandable last 2 and the heel portion of the expandable last 2. The forefoot spring portion 56 and the heel spring portion 57 may in particular be made of a metal strip having a width between 1 cm and 3 cm, in particular a width of between 1 cm and 2 cm.

    [0227] In the exemplary embodiment of FIG. 11, the forefoot spring portion 56 and the heel spring portion 57 are made from a continuous metal strip, i.e. they are provided as an integrated one-piece structure. However, it is also possible that the forefoot spring portion 56 and the heel spring portion 57 are separate elements, with each of these separate elements being mounted to the lid 10 or to the core support element 4.

    [0228] An exception to the constant width of the forefoot spring portion 56 and the heel spring portion 57 are the pressure exertion pad 56c at the toe portion of the forefoot spring portion 56 and the pressure exertion pad 57a the heel portion of the heel spring portion 57. The pressure exertion pads 56c, 57a have a wider extension than the forefoot spring portion 56 and the heel spring portion 57, thus providing for a somewhat more extended application of pressure onto the expandable shell 6.

    [0229] The spring action of the spring skeleton 55 is described as follows. Both the forefoot spring portion 56 and the heel spring portion 57 are configured to exert a spring force that pushes the forefoot spring portion 56 and the heel spring portion 57 upwards in the expandable last 2.

    [0230] In this context, the term upwards corresponds to the upwards direction in the viewing plane of FIG. 11, which also corresponds to the upwards direction of the footwear, when oriented in the normal use position. This upwards directed spring force is illustrated in FIG. 11 by the spring skeleton 55 being shown in two different positions/states. In particular, the spring skeleton 55 is on the one hand shown in phantom, with said position/state representing a potential positon/state directly after insertion of the expandable last 2 into a footwear. In this position/state, the forefoot spring portion 56 and the heel spring portion 57 are biased downwards, and the forefoot spring portion 56 and the heel spring portion 57 exert an upwards directed force. This upwards directed force pushes/forces the spring skeleton 55 in the second depicted position/state, being shown in solid lines. In this positon/state, the first exposed portion 56a exerts localized pressure onto the instep portion of the expandable shell 6, the second exposed portion 56b exerts localized pressure onto the toe portion of the expandable shell 6, and the heel end portion of the heel spring portion 57 exerts localized pressure onto the heel portion of the expandable shell 6. The first exposed portion 56a, which is roughly in the middle between the lid 10 and the toe end portion of the forefoot spring portion 56, exerts localized pressure in a substantially upward direction. The second exposed portion 56b which is a toe end portion of the forefoot spring portion 56, exerts localized pressure in a forward and upward direction. The heel end portion of the heel spring portion 57 exerts localized pressure in a rearward and upward direction.

    [0231] With the spring skeleton 55 of the expandable last 2 of FIG. 11, localized pressure may be exerted at particularly crucial portions, namely at the instep portion, the toe portion and the heel portion, with the particular directions of pressure being particularly effective for the attachment of the insert. The expansion assembly 40 of the expandable last 2 of FIG. 11 co-operates very well with the more uniform application of pressure via liquid introduced into the expandable shell 6 via the liquid port 16.

    [0232] It has been described that the spring skeleton 55 and the core support element 4 are jointly viewed as an expansion assembly. However, one can also view the spring skeleton 55 as an additional element that supplements the core support element 4. In particular, the core support element 4 may be embodied in any of the variations described above with respect to FIGS. 1 to 4, and the spring skeleton may be added thereto for exertion of localized pressure.

    [0233] FIG. 12 shows an expandable last 2 in accordance with an eleventh exemplary embodiment of the invention in a schematic longitudinal cross-sectional view. Various components of the expandable last 2 of FIG. 12 are identical/similar to the components of the expendable last discussed above. They are provided with corresponding reference numerals, and reference is made to their description above.

    [0234] The expandable last 2 of FIG. 12 is somewhat similar to the expandable last 2 of FIG. 11. In particular, the expandable last 2 of FIG. 12 also comprises an expansion assembly 40 that has a spring skeleton 55. In the exemplary embodiment of FIG. 12, the expandable last 40 does not have a core support element. However, the expandable last 40 of FIG. 12 may be additionally provided with a core support element, as described herein.

    [0235] The spring skeleton 55 of the expandable last 2 of FIG. 12 also has a forefoot spring portion 56 and a heel spring portion 57. The heel spring portion 57 is embodied in the same manner as the heel spring portion 57 of the spring skeleton 55 of FIG. 11. Reference is made to its description above.

    [0236] In the exemplary embodiment of FIG. 12, the forefoot spring portion 56 is substantially L-shaped from the lid 10 to its toe end portion. This substantially L-shaped structure may be ridged, as depicted in FIG. 12, or may exert an upwards spring force, as described with respect to the forefoot spring portion 56 of FIG. 11. The forefoot spring portion 56 of FIG. 12 comprises an instep spring element 58 that extends along the instep portion of the expandable shell 6. In particular, the instep spring element 58 extends from close to the toe portion of the described substantially L-shaped structure in an upward and rearward direction. The terms upward and rearward refer to the depicted orientation of FIG. 12, which corresponds to the orientation of the expandable last 2 when inserted into a footwear in its normal use orientation. It can also be said that the instep spring element 58 has its free end pointing in a rearward and upward direction.

    [0237] The instep spring element 58 is configured to exert localized pressure onto the instep portion of the expandable shell 6. For illustration, the instep spring element 58 is shown in two states/positions. On the one hand, the instep spring element 58 is shown in phantom, which may correspond to a positon/state directly after insertion of the expandable last 2 into the footwear. When in said positon/state, a spring action of the instep spring element 58 forces the instep spring element 58 upwards. This spring action leads to the instep spring element 58 being forced upwards and exerting localized pressure onto the instep portion of the expandable shell 6. Said pressure exertion position/state is shown in a solid line in FIG. 12.

    [0238] The expandable last 2 of FIG. 12 has similar properties as the expandable last 2 of FIG. 11. In particular, both rely on a spring skeleton 55 for exerting localized pressure. While both expandable lasts may be provided with a core support element or not, the substantially rigid L-shape of the forefoot spring element 56 of the expandable last 2 of FIG. 12 provides more inherent support to the spring skeleton 55, thus making it easier to provide the expansion assembly 40 without the core support element.

    [0239] FIG. 13 shows an expandable last 2 in accordance with a twelfth exemplary embodiment of the invention in a longitudinal cross-sectional view. Various components of the expandable last 2 of FIG. 13 are identical/similar to the components of the expandable lasts discussed above. They are provided with corresponding reference numerals, and reference is made to their description above.

    [0240] The expandable last 2 of FIG. 13 has an expandable shell 6, mounted to a lid 10. For the description of the expandable shell 6 and the lid 10, reference is made to the description of the expandable lasts discussed above.

    [0241] Within the expandable shell 6, a granulate chamber 61 is provided. A granulate port 62 is provided in the lid 10. The granulate port 62 forms a granulate channel into the granulate chamber 61. Via the granulate port 62, granulate 63 may be introduced into the expandable shell 6 and may be sucked out of the expandable shell 6. For illustrative purposes, a small amount of granulate 63 is shown within the granulate chamber 61 in FIG. 13. In the exemplary embodiment of FIG. 13, the granulate 63 is provided in the form of metal or glass balls, in particular metal or glass balls having a diameter of between 2 mm and 8 mm, further in particular having a diameter of between 3 mm and 6 mm. The metal may be steel. It is also possible that the granulate is provided in the form of sand.

    [0242] The granulate 63 that is introduced into the granulate chamber 61 may be provided by an external granulate source 64. The external granulate source 64 has a granulate container 65 and a granulate heater 67. The granulate container 65 is coupled to the granulate port 62 with a granulate dosing valve 66, being interposed between the granulate container 65 and the granulate port 62. Via the granulate heater 67 and the granulate dosing valve 66, the amount and temperature of the granulate 63 within the expandable shell 6 of the expandable last 2 may be controlled.

    [0243] In operation, the granulate 63 may provide for a substantially uniform pressure onto the insert for pressing the same against the footwear. Also, with the granulate 63 being heated, the granulate 63 is an effective means for activating a heat-activated adhesive, which may be used for attaching the insert to the footwear. As described above, the expandable shell 6 may have, at least in one or more regions thereof, dimension-specific elastic properties. Also, as described above, a form-stable core support element or an expansion assembly may be arranged within the expandable shell 6. In this way, localized exertion of pressure may be combined with the more uniform exertion of pressure, as achieved via the granulate 63.

    [0244] The expandable shell 6 of the expandable last 2 of FIG. 13 may be made from latex material, as described above with respect to various other embodiments of the expandable last. It is also possible that the expandable shell 6 of the expandable last 2 of FIG. 13 is made of synthetic material, in particular of a textile material. The expandable shell 6 may for example by a nylon sock.

    Test Methods and Definitions

    [0245] The waterproofness of footwear may be determined by use of the Centrifuge test described in U.S. Pat. No. 5,329,807, and incorporated by reference herein in its entirety. The centrifuge tests may be carried out for 30 minutes. The footwear article is considered to be waterproof if no leakage is seen after 30 minutes.

    [0246] The breathability of footwear may be assessed in accordance with the determination of the Whole Boot Moisture Vapor Transmission Rate Test in accordance with the Department of Defense Army Combat Boot Temperate Weather Specifications. The specifications are as follows:

    [0247] Whole Boot Breathability

    [0248] The boot breathability test shall be designed to indicate the Moisture Vapor Transmission Rate (MVTR) through the test sample by means of a difference in concentration of moisture vapor between the interior and the exterior environment.

    [0249] Apparatus [0250] a. The external test environment control system shall be capable of maintaining 23 (±1) ° C. and 50%±2% relative humidity throughout the test duration. [0251] b. The weight scale shall be capable of determining the weight of test samples filled with water to an accuracy of (±0.01) gram. [0252] c. The water holding bag shall be flexible so that it can be inserted into the test sample and conform to the interior contours; it must be thin enough so that folds do not create air gaps; it must have much higher MVTR than the footwear product to be tested; and it must be waterproof so that only moisture vapor contacts the interior of the footwear product rather than liquid water. [0253] d. The internal heater for the test sample shall be capable of controlling the temperature of the liquid water uniformly in the test sample to 35 (±1) ° C. [0254] e. The sealing method around the collar of the test sample shall be impervious to both liquid water and water vapor.

    [0255] Procedure [0256] a. Place sample in test environment and condition for at least 12 hours. [0257] b. The heating device is inserted into the water holding bag and the complete assembly is then placed into the test sample opening and filled with water to a height of 5 cm measured from inside sole. [0258] c. Seal opening around the collar with plastic wrap around the top of the footwear and tape over using packaging tape. [0259] d. Heat water in test sample to 35° C. [0260] e. Weigh test sample and record as Wi. [0261] f. Hold temperature in test sample after weighing for a minimum of 4 hours. [0262] g. After a minimum of 4 hours, reweigh test sample. Record weight as Wf and test duration as Td. [0263] h. Calculate MVTR of the test sample in grams/hour from the equation below:


    MVTR=(Wi−Wf)/Td.

    [0264] This test is in accordance with ASTM D8041 (2016).

    [0265] For example, for a low ankle shoe of European shoe size 42, the footwear may be considered breathable if above calculated value is above 1.5 grams/hour. For larger/smaller shoe sizes, said limit value may be extrapolated in accordance with the increased/decreased surface area of the shoe.

    [0266] The waterproofness and the breathability of the bootie as a whole may also be determined by use of the Centrifuge test and the Whole Boot Moisture Vapor Transmission Rate Test, respectively, as laid out above.

    [0267] While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.