METHOD AND INJECTION MOLDING SYSTEM FOR THE DIRECT SOLING OF A MULTILAYERED SHOE SOLE

Abstract

Some embodiments relate to a method for the direct soling of a multilayered shoe sole. The method can provide two distinct sets of mold frames for a first and a second shoe sole layer and a distinct order for the soling of the layers. In contrast to art traditional approaches, a first layer (e.g. a midsole) is first soled to an upper in a first mold frame and subsequently a second layer (e.g. an outer sole) is soled onto said first layer in a second mold frame. The method can allows for an increased design flexibility and the inclusion of additional functional or aesthetic features, such as air pockets, undercuts, toe caps or running sole tips previously not possible with direct soling processes. Some embodiments relate to an injection molding system equipped and configured for carrying out the method.

Claims

1. A method for direct soling a multilayered shoe sole onto a shoe upper, comprising providing an injection molding system comprising two mold frames, positioning a last covered with the upper into a first mold frame to form a first molding cavity, injecting a first molding material into the first molding cavity to directly sole a first layer of the shoe sole onto the upper, subsequently, positioning the last, covered with the upper and soled with the first layer, into a second mold frame to form a second molding cavity, and injecting a second molding material into the second molding cavity to directly sole a second layer of the shoe sole onto said first layer.

2. The method according to claim 1, wherein a first mold frame comprises multiple first lateral molding frame elements and a first base stamp, and a second mold frame comprises multiple second lateral molding frame elements and a second base stamp.

3. The method according to claim 2, wherein soling a first shoe sole layer onto the upper in a first mold frame comprises: clamping the last that is covered with the upper using the first lateral molding frame elements, such that the upper seals a top of the first molding cavity, injecting the first molding material via a sprue, formed by the multiple first lateral molding frame elements, into the first molding cavity, raising the first base stamp such that the sprue is closed and allowing for a reaction of the first molding material to form the first layer of the shoe sole, and lowering the first base stamp and opening the first lateral molding frame elements or vice versa to release the upper soled with the first layer from the first mold frame.

4. The method according to claim 2, wherein soling a second shoe sole layer onto the first layer in the second mold frame comprises: clamping the last that is covered with the upper and soled with a first layer with the second lateral molding frame elements such that the upper soled with a first layer seals a top of the second molding cavity, injecting the second molding material via a sprue, preferably formed by the second lateral molding frame elements, into the second molding cavity, raising the second base stamp such that the sprue is closed and allowing for a reaction of the second molding material to form the second layer of the shoe sole, and lowering the second base stamp and opening the second lateral molding frame elements or vice versa to release the upper soled with the first and second layer from the second mold frame.

5. The method according to claim 1, wherein the first layer of the shoe sole comprises a midsole and the second layer of the shoe sole comprises an outer sole.

6. The method according to claim 1 wherein the first mold frame comprises multiple first lateral molding frame elements and a first base stamp, wherein the first base stamp comprises structuring elements.

7. The method according to claim 1, wherein the second mold frame comprises multiple second lateral molding frame elements and a second base stamp, wherein the second base stamp comprises a profile for a lateral and/or lower surface of a mid-and/or outer sole.

8. The method according to claim 1, wherein the first layer of the shoe sole comprises or consists of a first midsole and the second layer of the shoe sole comprises or consists of a second midsole.

9. The method according to claim 1, wherein the second mold frame comprises multiple second lateral molding frame elements and a second base stamp onto which a prefabricated outer sole is positioned.

10. The method according to claim 1, wherein the first and second molding materials are provided prior to injection by mixing one or more base materials with one or more additives, wherein the one or more base materials are a polyol and an isocyanate, such that a polyurethane is formed as a molding material and/or wherein the one or more additives are selected from the group consisting of a color additive, a hardener, a softener, a crosslinker, gasing agent, a propellant, a cell opener or a stabilizer.

11. A shoe produced using the method claim 1, the shoe with comprising a multilayer shoe sole exhibiting features selected from the group consisting of a midsole with air pockets, undercuts of midsole material, sole parts made from an outer sole material directly connecting with the upper, for instance forming a toe cap or a running sole tip, sole parts made from an outer sole material disconnected from a bottom outer sole, for instance for providing a heel cap or wedges, or a bottom sole exhibiting disjunct patches of outer sole material.

12. An injection molding system for direct soling a multilayered shoe sole onto a shoe upper, comprising: an injection unit; a mold frame for receiving a shoe last covered with an upper (3) to form a molding cavity, and a control unit, wherein the injection unit is connectable to the mold frame, such that molding material is injectable into the molding cavity to form a layer of a shoe sole, wherein the injection molding system comprises two mold frames, and the control unit is configured to: position a last covered with the upper into a first mold frame to form a first molding cavity, inject a first molding material into a first molding cavity to directly sole a first layer of the shoe sole onto the upper, subsequently, position the last covered with the upper and soled with the first layer into a second mold frame to form a second molding cavity, and inject a second molding material into the second molding cavity to directly sole a second layer of the shoe sole onto said first layer.

13. The injection molding system according to claim 12, wherein the injection unit comprises a nozzle and the mold frames each comprise multiple lateral molding frame elements forming a sprue, wherein the nozzle is connectable to the sprue to inject molding material into a molding cavity to form a layer of a shoe sole.

14. The injection molding system according to claim 12, wherein the injection unit comprises a mixing head with at least one, valve inlets for one or more base materials and one or more additives, wherein the mixing head is configured to mix the one or more base materials with the one or more additives to form the molding material.

15. The injection molding system according to claim 12, wherein the injection molding system comprises three or more pairs of mold frames mounted on a rotatable table, wherein the control unit is configured to rotate each of the mold frames to connect to a stationary injection unit.

16. The injection molding system according to claim 14, wherein the at least one valve inlet comprises at least two valve inlets.

17. The method according to claim 6, wherein the structuring elements comprise structural elevations and/or structural depressions.

18. The method according to claim 17, wherein the structuring elements are selected from the group consisting of: ridges, pillars, pins, holes or grooves.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0213] FIG. 1 Illustration of multilayered shoe soles with special features that are possible using a direct soling process as described herein.

[0214] FIG. 2 Illustration of preferred method steps for an “over molding” of a midsole with outer sole material, e.g. to provide a running sole tip or a toe cap.

[0215] FIG. 3 Illustration of preferred method steps for an “under molding” of outer sole material through channels of a midsole, e.g. to provide a heel cap or a wedge of outer sole material within the midsole (left: longitudinal sectional view, right: cross sectional view).

[0216] FIG. 4 Illustration of preferred method steps for the molding of “patches”, e.g. patches of outer sole material on a midsole (left: longitudinal sectional view, right: cross sectional view).

[0217] FIG. 5 Illustration of preferred method steps producing midsoles with air pockets.

[0218] FIG. 6 Illustration of preferred method steps for producing multilayered shoe soles using prefabricated components, e.g. prefabricated outer soles.

DETAILED DESCRIPTION OF THE FIGURES

[0219] Processes for the manufacturing of shoe soles using injection molding systems as for instance described in DE 10 2015 108 086 or U.S. Pat. No. 3,915,608 typically include the following steps:

[0220] 1. The control unit initiates rotation of the rotary table/movement of the clamping unit in front of the reaction casting unit

[0221] 2. The mold frame or clamping unit, in which a molding cavity may be formed by means of two lateral molding elements, a base stamp and a shaft covered with an upper as a closing element, rotates/is moved in front of the nozzle mouthpiece of an injection unit.

[0222] 3. The control unit initiates the translation of the injection unit to drive the nozzle mouthpiece against the sprue of the mold frame

[0223] 4. The control unit initiates the mixing of the components of the molding material according to preset parameters. Within a mixing chamber of a mixing head of the injection unit chemical components of the required formulation are mixed and transported by means of a mixing screw into the mouthpiece. Within the mixing chamber the material is mixed through a mixing screw rotating at approx. 15,000-18,000 rpm. During the mixing of the main material components polyol and isocyanates (=PU), color additives, hardeners, blowing agents or other additives may be added at the same time in order to achieve the material characteristics required for the sole.

[0224] 5. The control unit initiates the injection process. The molding material mixture is injected in the parameterized amount and speed via the sprue into the molding cavity. The distribution of the molding material is governed by the impact point of the molding material and the selected viscosity.

[0225] Unitary shoes soles will have the same characteristics (hardness, density, color, rebound, etc) along the length, width and thickness of the sole. For a multi-section injection process as e.g. described in DE 10 2015 108 086 A, the shoe sole can be subdivided into different sections with different characteristics (e.g. regarding hardness etc.).

[0226] 6. The control unit initiates termination of the injection process. To this end the inlets of the mixing head for receiving components of molding material are closed and the mixing and transport of the molding material is terminated.

[0227] 7. The control unit initiates the raising of the base element. Typically, the base element is raised to a position that closes the sprue, such that no molding material can flow or foam out of the molding cavity back into the nozzle and injection unit.

[0228] 8. In order to produce further shoe soles the control unit initiates a rotation or other preferred movement towards the next position.

[0229] 9. The material will now react according to predetermined parameters and will be ready to be taken out after a predetermined time.

[0230] 10. After the predetermined reaction time, the lateral mold frames are opened and the base stamp is lowered or vice versa. In addition, the last covered with the upper, soled with a midsole and/or outer sole is lifted, such that the soled shoe floats freely in the cavity and be removed.

[0231] A direct soling process for a multilayered shoe sole in the prior art was based on first inserting or injecting an outsole into the bottom stamp (PU, TPU or rubber with respective reaction times) and then injecting the PU material for the midsole, thereby permanently connecting the shoe sole (lower limit of the cavity) and the shoe shaft (upper limit of the cavity).

[0232] As described herein the method according to the invention differs by a reversed order for soling the layers and providing distinct sets of mold frames for the first layer (e.g. midsole) and the second layer (e.g. an outer sole).

[0233] Thereby, the provision of multilayer shoe soles with special features such running sole tip, air pockets, heel caps, wedges etc. is possible for the first time using a direct soling process (see FIG. 1).

[0234] The following examples illustrate preferred embodiments on how to structure the first, second mold frames and/or the injection process in order to yield the desired special features.

[0235] FIG. 2 illustrates preferred method steps for a “over molding” (e.g. to provide a running sole tip or a toe cap). FIG. 2A illustrates the processing of a shoe last covered with an upper in a first clamping unit or first mold frame, while FIG. 2B illustrates the subsequent processing of a shoe last covered with an upper and soled with a first layer in a second clamping unit or second mold frame,

[0236] The depicted method comprises the steps of: [0237] clamping the last that is covered with the upper 3 by means of the first lateral molding frame elements 5, such that the upper 2 seals the top of the first molding cavity 13, [0238] injecting the first molding material 7 for a midsole via a sprue 15 into the first molding cavity 13, [0239] raising the first base stamp 11 such that the sprue 15 is closed and allowing for a reaction of the first molding material 7 to form the midsole 9, [0240] lowering the first base stamp 11 and opening the first lateral molding frame elements 5 or vice versa to release the upper 2 soled with the midsole 9 from the first mold frame and—if necessary—removing the flash 20 [0241] transferring the last covered with an upper and soled with the midsole 4 to a second mold frame [0242] clamping the last that is covered with the upper and soled with a midsole 4 with the second lateral molding frame elements 6 such that the upper 2 soled with the midsole 9 seals the top of the second molding cavity 14, [0243] injecting a second molding material 8 for an outer sole via a sprue 15 into the second molding cavity 14, [0244] raising the second base stamp 12 such that the sprue 15 is closed, wherein the raising of the second base stamp 12 results in the covering of outer sole molding material 8 at least in parts over the midsole 9, preferably until a connection to the upper 2 is made [0245] allowing for a reaction of the molding material 8 for an outer sole to form the outer sole 10, [0246] lowering the second base stamp 12 and opening the second lateral molding frame elements 6 or vice versa to release the upper 2 soled with the midsole 9 and the outer sole 10 from the second mold frame and removing the flash 20.

[0247] The example allows for instance for providing a two-layered shoe sole, the outer sole of which covers the upper directly and thus protects the upper from wear (e.g. to form a running sole tip or a toe cap, see FIG. 1a or FIG. 1e) Moreover, the embodiment allows for the provision of footwear, wherein the multilayered sole is characterized by a flexible color separation, which is independent of previous limitations regarding undercut-free separation surfaces between a bottom stamp and lateral frame molding elements (see FIG. 1d).

[0248] FIG. 3 illustrates the preferred method steps for an “under molding” (e.g. to provide a heel cap or a wedge of outer sole material within the midsole). FIG. 3A illustrates the processing of a shoe last covered with an upper in a first clamping unit or first mold frame, while FIG. 3B illustrates the subsequent processing of a shoe last covered with an upper and soled with a first layer in a second clamping unit or second mold frame,

[0249] The depicted method comprises the steps of: [0250] clamping the last that is covered with the upper 3 by means of the first lateral molding frame elements 5, such that the upper 2 seals the top of the first molding cavity 13, wherein the first base stamp 11 exhibits structural elevations 16 such as ridges, pillars and/or pins, [0251] injecting the first molding material 7 for a midsole via a sprue 15 into the first molding cavity 13, [0252] raising the first base stamp 11 such that the sprue 15 is closed, wherein the structural elevations 16 such as ridges, pillars and/or pins seal with the upper 2 and/or the first lateral molding frame elements 5 to produce channels 17 within the midsole 9 and allowing for a reaction of the first molding material 7 to form the midsole 9, [0253] lowering the first base stamp 11 and opening the first lateral molding frame elements 5 or vice versa to release last covered with the upper 2 and soled with the midsole 9 from the first mold frame and—if necessary—removing the flash 20, [0254] transferring the last covered with the upper and soled with the midsole 4 to a second mold frame, [0255] clamping the last that is covered with the upper and soled with a midsole 4 with the second lateral molding frame elements 4 such that the upper 2 soled with the midsole 9 seals the top of the second molding cavity 14, [0256] injecting the second molding material 8 for an outer sole via a sprue 15 into the second molding cavity 14, [0257] raising the second base stamp 12 such that the sprue 15 is closed, wherein the outer sole molding material 8 flows through channels 17 within the midsole 9 towards upper regions of the second molding cavity 14, [0258] allowing for a reaction of the molding material 8 for an outer sole to form the outer sole 10, [0259] lowering the second base stamp 12 and opening the second lateral molding frame elements 6 or vice versa to release the upper 2 soled with the midsole 9 and outer sole 10 from the second mold frame and removing the flash 20.

[0260] The embodiment allows for instance for providing a two-layered shoe sole, the outer sole of which covers the upper directly and does not exhibit visible connection to the bottom of the outsole. Hereby, it is possible to structurally support or color certain areas of the shoe as desired (e.g. by providing a heel cap see FIG. 1b). To this end the first base stamp may exhibit at least two ridges that are oriented along the length of the base stamp and positioned symmetrically towards the left and right lateral sides as depicted. Moreover, the example allows for producing shoes with two-layered soles, wherein the outer sole material is placed inside the midsole with no visible connection either to the upper or the bottom of the outer sole. Hereby, it is possible to provide a visible or structural support to certain areas within the midsole (e.g. pronation support, preferably as wedges see FIG. 1c).

[0261] FIG. 4 illustrates the method steps for a preferred molding of “patches” (e.g. patches of outer sole material on a midsole). FIG. 4A illustrates the processing of a shoe last covered with an upper in a first clamping unit or first mold frame, while FIG. 4B illustrates the subsequent processing of a shoe last covered with an upper and soled with a first layer in a second clamping unit or second mold frame,

[0262] The depicted method comprises the steps of: [0263] clamping the last that is covered with the upper 3 by means of the first lateral molding frame elements 5, such that the upper 2 seals the top of the first molding cavity 13 [0264] injecting the first molding material 7 for a midsole via a sprue 15 into the first molding cavity 13, [0265] raising the first base stamp 11 such that the sprue 15 is closed and allowing for a reaction of the first molding material 7 to form the midsole 9, [0266] lowering the first base stamp 11 and opening the first lateral molding frame elements 5 or vice versa to release the last 4 covered with the upper 2 and soled with the midsole 9 from the first mold frame and—if necessary—removing the flash 20, [0267] transferring the last 4 covered with the upper 2 and soled with the midsole 9 to a second mold frame [0268] clamping last 4 covered with the upper 2 and soled with the midsole 9 with the second lateral molding frame elements 6 such that the upper 2 soled with the midsole 9 seals the top of the second molding cavity 14, wherein the second lateral molding frame 6 elements exhibit bridges or bars 18, which extent laterally directly underneath the midsole 9 such that some bottom parts of the midsole 9 are contacted by said bridges or bars 18, [0269] injecting the second molding material 8 for an outer sole via a sprue 15 into the second molding cavity 14, [0270] raising the second base stamp 12 such that the sprue 15 is closed, wherein the second base stamp 12 preferably exhibits structural depressions 19, such as grooves or holes, which are complementary to said bridges or bars 18, such that raising of the second base stamp 12 results in a direct soling of outer sole material 8 onto the midsole 9 except for the parts covered by the bridges or bars 18 [0271] allowing for a reaction of the molding material 8 for an outer sole to form the outer sole 10, [0272] lowering the second base stamp 12, wherein parts of outer sole material 8 positioned underneath said bridges or bars 18 detach at tearing edges 21 [0273] opening the second lateral molding frame elements 6 to release the upper 2 soled with the midsole 9 and patches of an outer sole 10 from the second mold frame and removing flash 20.

[0274] The embodiment allows for providing a two-layered shoe sole, the outer sole of which is only to be molded onto certain areas of the midsole, e.g. in order to influence the rolling behavior (see FIG. 1f, top). Moreover, it is also possible to produce shoes with two-layered soles, in which both the midsole and the outsole are only to be molded onto certain areas of the upper, e.g. in order to influence the rolling behavior. To this end it may be preferred to include in addition bridges or bars for the first lateral molding frame elements, such that the midsole is only directly soled onto desired parts of the upper (see FIG. 1f, bottom).

[0275] FIG. 5 illustrates preferred method steps for producing midsoles with air pockets. FIG. 5A illustrates the processing of a shoe last covered with an upper in a first clamping unit or first mold frame, while FIG. 5B illustrates the subsequent processing of a shoe last covered with an upper and soled with a first layer in a second clamping unit or second mold frame,

[0276] The depicted method comprises the steps of: [0277] clamping the last that is covered with the upper 3 by means of the first lateral molding frame elements 5, such that the upper 2 seals the top of the first molding cavity 13, wherein the first base stamp 11 exhibits structural elevations 16 such as ridges, pillars and/or pins, [0278] injecting the first molding material 7 for a midsole via a sprue 15 into the first molding cavity 13, [0279] raising the first base stamp 11 such that the sprue 15 is closed and allowing for a reaction of the first molding material 7 to form the midsole 9, wherein the structural elevations 16 such as ridges, pillars and/or pins impede a solidification of the molding material 7 in a space, which will form air openings 22, [0280] lowering the first base stamp 12 and opening the first lateral molding frame elements 6 or vice versa to release the last covered with the upper and soled with the midsole 4 from the first mold frame, wherein the midsole 9 comprises air openings 22, which reflect the shape of said structural elevations 16 and—if necessary—removing the flash 20, [0281] transferring the last covered with the upper and soled with the midsole 4 to a second mold frame [0282] clamping the last that is covered with the upper and soled with a midsole 4 with the second lateral molding frame elements 6 such that the upper 2 soled with the midsole 9 seals the top of the second molding cavity 14, [0283] injecting the second molding material 8 for an outer sole via a sprue 15 into the second molding cavity 14, [0284] raising the second base stamp 12 such that the sprue 15 is closed, wherein the outer sole material 8 only partially enters said air openings 22 reflecting the shape of the structural elevations 16 such that air pockets 23 are produced at the respective sites and allowing for a reaction of the molding material 8 for an outer sole to form the outer sole 10, [0285] lowering the second base stamp 12 and opening the second lateral molding frame elements 6 or vice versa to release the upper 2 soled with the midsole 9 comprising air pockets 23 from the second mold frame and removing the flash 20.

[0286] The embodiment thus allows for the production of midsoles with air pockets according to a desired size and shape using a direct soling process to allow for instance for an improved dampening.

[0287] FIG. 6 illustrates preferred method steps for producing multilayered shoe soles using prefabricated components (e.g. prefabricated outer soles). FIG. 6A illustrates the processing of a shoe last covered with an upper in a first clamping unit or first mold frame, while FIG. 6B illustrates the subsequent processing of a shoe last covered with an upper and soled with a first midsole in a second clamping unit or second mold frame,

[0288] The depicted method comprises the steps of: [0289] clamping the last that is covered with the upper 3 by means of the first lateral molding frame elements 5, such that the upper 2 seals the top of the first molding cavity 13, [0290] injecting the first molding material 7 for a first midsole via a sprue 15 into the first molding cavity 13, [0291] raising the first base stamp 11 such that the sprue 15 is closed and allowing for a reaction of the first molding material 7 to form the first midsole 9, [0292] lowering the first base stamp 11 and opening the first lateral molding frame elements 5 or vice versa to release the last covered with the upper 2 and soled with the first midsole 9 from the first mold frame and removing the flash 20, [0293] transferring the last covered with the upper and soled with the midsole 4 to a second mold frame, [0294] clamping the last that is covered with the upper and soled with a first midsole 4 with the second lateral molding frame elements 6 such that the upper 2 soled with the first midsole 9 seals the top of the second molding cavity 14, wherein a prefabricated outer sole 24 is positioned on the second base stamp 12, [0295] injecting molding material 8 for a second midsole via a sprue 15 into the second molding cavity 14, [0296] raising the second base stamp 12 such that the sprue 15 is closed and allowing for a reaction of the molding material 8 for a second midsole to form a second midsole 10, which bonds the positioned prefabricated outer sole 24 with the first midsole 9, [0297] lowering the second base stamp 12 and opening the second lateral molding frame elements 6 or vice versa to release the upper 2 soled with a multilayered sole comprising a first midsole 9, a second midsole 10 and a prefabricated outer sole 24 from the second mold frame and removing the flash 20.

[0298] The embodiment allows to integrate prefabricated outer soles or stiffeners in multilayered shoes soles using a direct soling process as described herein.

LIST OF REFERENCE SIGNS

[0299] 2 upper

[0300] 3 shoe last covered with an upper

[0301] 4 shoe last covered with an upper to which a first layer is soled

[0302] 5 first lateral molding frame elements

[0303] 6 second lateral molding frame elements

[0304] 7 first molding material, e.g. for a midsole (or a first midsole)

[0305] 8 second molding material, e.g. for an outer sole (or a second midsole)

[0306] 9 first layer of the shoe sole, e.g. midsole

[0307] 10 second layer of the shoe sole, e.g. outer sole

[0308] 11 first base stamp

[0309] 12 second base stamp

[0310] 13 first molding cavity

[0311] 14 second molding cavity

[0312] 15 sprue

[0313] 16 structural elevations, preferably ridges, pillars or pins

[0314] 17 channels

[0315] 18 bridges or bars

[0316] 19 structural depressions, preferably grooves or holes

[0317] 20 flash

[0318] 21 tearing edge

[0319] 22 air openings

[0320] 23 air pockets

[0321] 24 prefabricated outer sole

[0322] I outer sole material attached to upper (e.g. running sole tip or toe cap)

[0323] p heel cap

[0324] q wedge of outer material within the midsole

[0325] m undercuts

[0326] o, r patches