METHOD AND APPARATUS FOR FOOTWEAR MOULDING

Abstract

The present invention provides a method of moulding a mouldable reinforcing element of an item of footwear. The method comprises the steps of: providing a microwave heatable mouldable reinforcing element and locating said element at an appropriate location as part of an item of footwear; positioning the item of footwear on a last to hold the item of footwear in an appropriate shape; locating the item of footwear in a microwave field within a microwave chamber that contains the microwave field and thereby heating the mouldable reinforcing element to a temperature at which it is mouldable; and moving the appropriate location of the item of footwear relative to the microwave field during said heating. The method is particularly advantageous over prior art microwave methods for moulding footwear in that it does not require specific control of the microwave field and it does not require the use of external moulds.

Claims

1.-17. (canceled)

18. A method of moulding a mouldable reinforcing element of an item of footwear comprising the steps of: providing a microwave heatable mouldable reinforcing element and locating said element at an appropriate location as part of an item of footwear; positioning the item of footwear on a last to hold the item of footwear in an appropriate shape; and then locating the item of footwear in a microwave field within a microwave chamber that contains the microwave field and thereby heating the mouldable reinforcing element to a temperature at which it is mouldable; and moving the appropriate location of the item of footwear relative to the microwave field during said heating.

19. A method according to claim 18, wherein the mouldable reinforcing element is a heel counter and the appropriate location is a back part of the item of footwear.

20. A method according to claim 18, wherein the mouldable reinforcing element is a toe puff and the appropriate location is a front part of the item of footwear.

21. A method according to claim 18, wherein the item of footwear is located on a movable mount within the microwave chamber and during heating the mount is moved within the chamber to move the item of footwear relative to the microwave chamber.

22. A method according to claim 21, wherein the mount is rotated during heating.

23. A method according to claim 22, wherein the mount is oscillated during heating.

24. A method according to claim 22, wherein the mount is oscillated or rotated asymmetrically within the chamber.

25. A method according to claim 18, where the microwave field within which the item of footwear is located is not stationary.

26. A method according to claim 25, wherein the microwave field is moved relative to the item of footwear using at least one mode stirrer.

27. A method according to claim 18, wherein the item of footwear is moved through the microwave field on a conveyor.

28. A method according to claim 18, wherein the last is formed of a microwave transparent material.

29. A footwear moulding heater comprising: a chamber; a microwave generator that, when in use, generates a microwave field within the chamber, wherein the microwave field is contained within the chamber; an apparatus for moving an item of footwear located in the chamber relative the microwave field; a support plate for locating the item of footwear, wherein the item of footwear is formed of microwave transparent material; and an actuator for moving the support plate relative to the chamber, wherein the actuator oscillates the support plate in the chamber.

30. The footwear heater of claim 29, further comprising a back part moulding heater according to claim 29.

31. The footwear heater according to claim 29, wherein the support plate is formed of HDPE or PTFE or polypropylene.

32. The footwear heater according to claim 29, wherein the support comprises one or more indented portions on an upper surface in which a shoe can be located.

33. The footwear heater according to claim 29, wherein the apparatus comprises at least one mode stirrer for moving the microwave field within the chamber and relative to a shoe located in the chamber.

34. The heater according to claim 29, wherein the heater is part of a system for moulding footwear components, the system comprising the heater and a conveyor for bringing an item of footwear to the heater; and an actuator for moving the item of footwear from the conveyor into the chamber of the heater and removing it after heating.

Description

[0054] Further features and advantages of the present invention will be apparent from the embodiments that are shown in the Figures and are described below.

[0055] Drawings

[0056] FIG. 1 is a diagram of a back part heater according to a first embodiment of the invention;

[0057] FIG. 2 shows the back part heater of FIG. 1 with an item of footwear positioned inside;

[0058] FIG. 3 shows a mode stirrer that may be used with a back part heater according to the present invention;

[0059] FIG. 4 shows the mode stirrer of FIG. 3 in position in the back part heater of FIG. 1;

[0060] FIG. 5 shows detail of a support plate of the back part heater of FIG. 1;

[0061] FIG. 6 is a cross-section of the back part heater of FIG. 1 showing detail of the actuator;

[0062] FIG. 7 is a schematic diagram of a first system for moulding footwear components comprising a back part heater according to the present invention; and

[0063] FIG. 8 is a schematic diagram of a second system for moulding footwear components comprising a back part heater according to the present invention

[0064] A back part heater 1 according to an embodiment of the present invention is shown in the Figures. The heater 1 comprises a chamber 2, two ports 3 for introducing microwave radiation, inspection apertures 4, a support plate 5, an actuator 6, and two magnetrons 7, each aligned with one of the ports 3.

[0065] Details of the support plate 5 can be seen in FIG. 5. The support plate 5 is mounted in the chamber at an upper end of the actuator 6. A lower surface 8 of the support plate 5 has a central mounting 9 formed therein by which the support plate can be fixed to the upper end of a shaft of the actuator 6. An upper surface 10 of the support plate 5 has two mounting indentations 11 formed therein. The indentations 11 are shaped to accept an item of footwear 12 and to hold the item of footwear 12 in position on the upper surface. The support plate 5 is formed from a microwave transparent material such as HDPE, polypropylene, or PTFE.

[0066] During use of the heater 1 an item of footwear 12 is positioned in each of the indentations 11 of the support plate 5. The items of footwear 12 may be a pair of shoes. Each of the items of footwear 12 is mounted on a last 17 to hold it in the appropriate position for moulding a back part of a shoe. In particular, the last 17 will be shaped to form a heel counter (not shown) positioned in the back part of the shoe 12 to an appropriate shape.

[0067] During operation of the heater 1 the actuator 6 operates to rotate the support plate 5 in an oscillating motion at variable angles. The actuator 6 is capable at rotating the support plate 5 at speeds from 0.5 rpm to 30 rpm. The angle of oscillation may be anywhere from 0 to 360 in a clockwise or counter clockwise direction. A shaft of the actuator 6 is capable of variations of height enabling a variation of height of the support plate 5 in the chamber 2. The shaft of the actuator 6 can be formed of either microwave transparent or microwave conducting material, The height of the support plate 5 may be varied during operation of the heater 1 in combination with the oscillating rotation of the support plate 5. Moving the support plate within the chamber 2 ensures uniform exposure of a back part of a shoe to a microwave field within the chamber 2 even if the microwave field within the chamber 2 is not uniform.

[0068] A mode stirrer 13 of a heater 1 according to the present invention is shown in FIG. 3. The mode stirrer 13 is used to disperse the microwave energy in the chamber 2 by continuously varying the resulting microwave field. The mode stirrer 13 is a rotating mechanical device comprising a conical swatch plate 14 having apertures 15 formed therein. In use the mode stirrer 13 is mounted immediately above a port 3 and is rotated to disperse the microwave energy as it introduced into the chamber 2 via the port 3 and provide a varying microwave field, which on average is more uniform. The mode stirrer 13 is an optional feature and may not be present in embodiments of the invention.

[0069] In use, microwave energy is introduced into the chamber by the magnetrons 7 via the ports 3. The entry ports 3 are covered by microwave transparent windows made of material such as PTFE or HDPE, although in alternative embodiments of the invention the entry ports 3 or uncovered. The ports 3 form waveguides to help guide the microwave energy from the magnetrons 7 into the chamber 2. In the embodiment shown in the Figures the magnetrons 7 generate microwaves at either 2450 MHz or 915 MHz although it is possible to use alternative microwave frequencies.

[0070] The heater 1 can be used to implement the method of the present invention in the following manner. An unmoulded heel counter (not shown) is positioned appropriately in the back part of each of the items of footwear 12. The items of footwear 12 are then. positioned on a last 17 to form the heel counter into an appropriate shape. The heel counter is formed of a material that is mouldable when heated and that is susceptible to microwave heating. The items of footwear 12 are then positioned in the chamber 2 in the indentations 11 in the upper surface of the support plate 5. The items of footwear 12 may be positioned in the chamber 2 through a door (not shown) in the side of the chamber 2.

[0071] When the items of footwear 12 are in position within the chamber 2 and the door is closed to seal the chamber, the actuator 6 is operated to oscillate the support plate 5 within the chamber 2 and the magnetrons 7 are operated to direct microwave energy into the chamber 2. If the heater 1 comprises one or more mode stirrers 13 these will be rotated to disperse the microwave energy in the chamber 2. As a result, the items of footwear 12 will be exposed to a microwave field and will be constantly moved relative to that field. This allows for uniform microwave heating of the heel counters.

[0072] After an appropriate amount of heating the magnetrons 7 will be turned off, the oscillation of the support plate 5 will be halted, and the items of footwear 12 will be removed from the chamber. The items of footwear 12 may then be moved on to further processing. An appropriate amount of heating is an amount that results in the heel counters being heated to a temperature at which they become mouldable. It is anticipated that the skilled person would be able to optimise any particular embodiment of the present invention to allow this to happen based on the power of the magnetrons 7, the specific items of footwear 12, the material of the heel counters, and other relevant engineering considerations. Whilst it is necessary that the heel counters are heated to a sufficient temperature it is undesirable to overheat the heel counters as this can damage them or the items of footwear 12 in which they are contained.

[0073] It is anticipated that only components of items of footwear 12 that are susceptible to microwave heating will be significantly heated during use of the heater 1 according to the method of the present invention. Other components that are not susceptible to microwave heating will remain cool and will only be heated to the extent that they absorb heat from the microwave heated components.

[0074] From trials conducted using the embodiment of the invention of FIGS. 1 to 6, a pair of lasted uppers comprising microwavable counters were successfully uniformly activated in under 15 seconds using a 2 kW, 2.45 GHz microwave field. The support plate was oscillated through an angle of rotation of 20 at a frequency of 3.5 rpm. The counters achieve a temperature of 95 C. whilst the adjoining uppers were heated to only 45 C. No detrimental effects of this process on either the uppers or the counters were discovered. This result has been achieved for a variety of footwear sizes and types. The trials were equally successful for synthetic easily wrinkled, stretchy, non-stretchy materials,and leather. For leather footwear the upper temperature may be raised above 45 C. due to microwave heating resulting from oil, moisture and pigment content in the material. Leather uppers that have been successfully processed using the apparatus of

[0075] FIGS. 1 to 6 were heated to substantially lower temperatures than would be obtained if they had been processed traditional backpart moulding, in particular none of the leather uppers were heated above 90 C.

[0076] As the microwavable counters were selectively microwave heated the adjoining uppers were heated to a significantly lower temperature than in conventional moulding techniques, where the upper temperature would be at least as high as the temperature of the counter. This provides significant benefits. For example, the heated product is easier to handle, there is less risk of damage to the uppers, and the cooling time can be significantly shorter, potentially eliminating the need for a cooling stage in the manufacturing process. In addition minimising the heating of the uppers introduces the possibility of using materials that would not previously have been considered due to their intolerance of high temperatures.

[0077] A first system for moulding footwear components comprising a back part heater 1 according to the present invention is shown in FIG. 7. The system comprises a back part heater 1 according to the present invention, a first conveyor 20, a first shield screen 21, a second conveyor 22, a second shield screen 23, and an actuator 24.

[0078] A second system for moulding footwear components comprising a back part heater 1 according to the present invention is shown in FIG. 8. The system comprises a back part heater 1 according to the present invention, a conveyor 30, a shield screen 31, and an actuator 32.

[0079] The back part heaters 1 of the systems of FIGS. 7 and 8 is substantially as shown in FIGS. 1 to 6 and as described above with the exceptions that the support plate 5 is removable and that the back part heater 1 of the system of FIG. 7 is openable on a first side and an opposing second side. The back part heater 1 of the system of FIG. 8 is openable only on a first side.

[0080] The system of FIG. 7 operates in the following manner.

[0081] An unmoulded heel counter (not shown) is positioned appropriately in the back part of items of footwear 12. The items of footwear 12 are then positioned on a last to form the heel counter into an appropriate shape. The heel counter is formed of a material that is mouldable when heated and that is susceptible to microwave heating. The items of footwear are then position in the indentations in the upper surface of a support plate 5. The support plate 5 is then placed on the upper surface of an outer end of the first conveyor 21. The first conveyor 21 then moves the support plate from its first end to a second end that is adjacent the back part heater 1 and within the first shield screen 21. At this point the back part heater 1 is opened at both a first side adjacent the first shield screen 21 and a second side adjacent the second shield screen 23. The actuator 24 then acts to move the support plate 5 from the first conveyor 20 into the chamber 2 of the back part heater 1 such that the support plate 5 is appropriately located on the actuator 5 of the chamber 2. The back part heater 1 is then closed and the items of footwear 12 are microwave heated whilst being oscillated in the manner described above.

[0082] When the heating of the items of footwear 12 is completed the back part heater 1 is opened. The actuator 24 then acts to move the support plate 5 and the items of footwear 12 from the chamber 2 to a first end of the second conveyor 22 that is positioned within the second shield screen 23. The second conveyor 22 then moves the items of footwear 12 from the first end to a second end. The items of footwear 12 are then removed from the system.

[0083] The first screen shield 21 and the second screen shield 22 act to protect users from mechanical entrapment by the actuator 24 and any other moving parts of the system.

[0084] If the back part heater 1, and in particular any microwave field generated therein, is suitably formed it may be possible for the chamber 2 of the back part heater 1 to be permanently open at its first side and its second side.

[0085] As will be readily understood and as shown in the Figure, multiple items of footwear can be processed by the system of FIG. 7 consecutively. The system of FIG. 7 is intended to be an automated part of a footwear production line.

[0086] The system of FIG. 8 operates in a similar manner to the system of FIG. 7 with the exception that items of footwear are moved by the actuator 32 from the conveyor 30 into the chamber 24 and, after microwave heating, are then moved back onto the same conveyor from the same side of the chamber 2.