WO2015075435A1

WO2015075435A1 - A heel counter and/or toe puff heater

Info

Publication number: WO2015075435A1
Application number: PCT/GB2014/053409
Authority: WO
Inventors: Simon Paul Bradshaw; Tej POCHIRAJU
Original assignee: Texon Management Ltd
Priority date: 2013-11-19
Filing date: 2014-11-19
Publication date: 2015-05-28
Also published as: GB2520357A; GB201320427D0

Abstract

The present invention provides an apparatus (1) and method for heating heel counters and toe puffs. The apparatus (1) and method are advantageous as they utilise microwave heating, rather than conventional conduction heating to heat a heel counter or toe puff. This can result in much faster heating of the heel counter or toe puff and much less heating of adjoining components: of a shoe. The apparatus (1) and method of the present invention can only be used to form heel counters or toe puffs formed of suitable materials that heat under the action of microwaves. The apparatus (1) includes integral cooling means that cool a heel counter or toe puff after heating whilst in-situ within the apparatus, thereby removing the need for an additional cooling station. The method of the present invention includes the step of cooling a heel counter or toe puff within a heater.

Description

A Heel Counter and/or: Toe Puff Heater

Fiel j^j gn ion

The present mvent!on relates to the manufacture of footwear. In particular, the: present invention relates to the heating and moulding of heel counters and toe puffs during the manufacturing process. The invention provides a heel counter and/or toe puff heater and a method of heating heel counters :and toe puffs that are particularly advantageous compared to prior art apparatus and methods as they utilise microwave heating. Background

Many items of footwear contain heel counters and/or toe puffs. Heel counters are generally formed of resilient polymers that are formed into a suitable shape and provide structure, strength and protection to the heel region of the footwear. Toe puffs are also generally formed of resilient polymers that are formed into a suitable shape and provide structure, strength and protection to the toe region of the footwear. A major function of both heel counters and toe puffs is to stiffen the relevant part of the footwear.

It is often necessary to heat both heel counters and toe puffs during manufacture of footwear. .In particular, this is done during, or immediately before, a moulding stage when the heel counter or toe puff is moulded into the desired shape. This because the materials used to form heel counters and toe puffs are necessarily rigid at room temperature and it is necessary to heat the materials to make them flexible enough to mould.

Generally, heel counters and toe puffs are heated and moulded in -situ. That: is, heel counters and toe puffs are heated when they form part of at least partially formed piece of footwear. In particular, the heel counters and toe puffs may be heated at the same time as other components of the footwear, such as leather or synthetic upper layers. For example, a heel counte of a sports shoe may be heated whilst fixed to a polyurethane foam upper layer. This may be problematic as, while it is .necessary to heat the heel counter or toe puff to high temperature in order for it to be. moulded, it may not beneficial to heat the other components of the footwear. Further, after heating it is necessary to cool a counter or toe puff in order to ensure shape retention., Heating other components of the footwear hinders the cooling process due to heat retained in those components, A related issue is that the presence of other components will slow conductive heating of a heel counter or toe puff and it is necessary to heat those other components to temperatures higher than the desired temperature of th counter or puff in-order to heat the counter or puff sufficiently.

Currently, heei counters are heated using a back part moulding machine. These machines utilise either heated air and/or heated moulds to heat the counter and a two part mould to mould the counter into a suitable shape. The hee! counter Is heated to between 80°C and 90^QC depending upon the specific material from which they are formed, if the mould is heated the parts of mould are generally formed of metal and are heated to between 1 10°C and 160°C. Heel counters and toe puffs are heated by inserting the appropriate component into the mould pressing the parts of the mould together and heating the components for between 30 and 40 seconds. After heating the components are removed from the moulding machine and are cooled at a cooling station. It is desirable to cool the components to 20°C, However, as it is not only the heei counter that is heated, the cooling process is relatively slow. A typical cooling cycle only lasts 30 seconds and this is: insufficient to reach the target temperature, of 2Q°C. Therefore, the components are generally not cooled to the optimum temperature but remain heated.

As will be readiiy appreciated, the current method of back part moulding has a number of issues. Components other than the heel counter are heated during the moulding, which is not desirable. Additionally and as a result, it is difficult to rapidly cool the counters after heating. Finally, the whole process is relatively slow, and can take over a minute to heat and cool an individual back part. In light of this it would be beneficial to have an apparatus and method that would allow more directed and quicker heating of the counter wit less heating of the other components.

Toe puff moulding is carried out in a very similar manner and the same problems are applicable to their moulding. Therefore, it would also be beneficial to have a method and apparatus that would allow more directed and quicker heating of a toe puff with less heating: of other components. Summary of the invention

Th present Invention provides a heel counter and/or toe; puff heater comprising: an inner mould;

an outer mould;

a space formed defined by the inner mould and the outer mould that is sized to contain and constrain an appropriate part of a piece of footwear;

a microwave generator that, when in use, directs microwave radiation to the space; and

cooling means for cooling the inner mould and/or cooling means for cooling the outer mould.

The apparatus of the present invention is advantageous as it uses microwave heating, rather than conventional conduction heating, to heat a heel counter or toe puff. Microwave heating provides many benefits, Most importantly, microwaves can be directed to heat only the counter or puff thereby minimising heating of other components that are attached to the counter or puff. There is no need to heat the other components. Further, as the microwaves can be directed to heat only the counter or puff it is not necessar to heat either the inner mould or the outer mould. Instead the inner and outer moulds can be used as heat sinks to cool the counter or puff. This means the apparatus of the present invention can also be used to cool a counter or puff after heating and there may be no need for an additional cooling station. This can be extremely beneficial as it removes the need to take footwear from a healing station to a cooling station thereby greatl improving the time and efficiency of the manufacturing process.

Microwave heating can also be much quicker than conventional heating, thus the apparatus of the presentinvention can heat a counter or puff much more quickly than apparatus according to the prior art. As the other components of a shoe are not heated substantially by the apparatus it is also possible to use much more intense heating than would be otherwise possible.

In order for the present invention to operate optimally it is necessary that the counter or puff heated by the apparatus of the present invention are suitable for microwave heating, in particular, it is necessary that the materials from which the counters or puffs are formed have a high microwave absorpiion.Some toe puffs and heel counters: are formed of materials that have a suitably high microwave absorption. The. skilled person will be readily able to determine these toe puffs and heel counters.

Further toe puffs and heel counters formed of materials, with a suitably high microwave absorption are considered to be a separate but related invention and are the subject- matter of a UK patent application 1320430.0 entitled "Toe Puffs and Heel Counters" that was filed by Texon Management Ltd on 19 November 2013. Although it is beneficial to use the materials that are the subject-matter of that application it is to be understood that the apparatus of the present invention can be used with toe puffs and heel counters formed of materials that have previously been used for such components. The skilled person will readily understand, or will be easily able to determine by routine experimentation, which materials: are suitable for use with the apparatus of the present invention.

The apparatus of the present invention may not substantially heat the inner mould and/or the outer mould, for example if the inner and/or outer moulds are formed of a material that is not susceptible to microwave heating. The moulds can be used as a heat sink to cool a toe puff or heel counter after its heating. The thermal conductivity of the moulds will allow the moulds to act as heat sinks to a certain degree, depending upon the thermal conductivity . of the material(s) from which the moulds are formed. However, this is generally insufficient to provide enough cooling. Therefore, the heater of the present invention further comprises cooling means for cooling the inner and/or outer moulds.

The heater may comprise any suitable cooling means that is apparent to the person skilled in the art may be used. For example, fluid cooling systems and/or additional external heat sinks could be used. Fluid cooling systems include gas, liquid, and muftt- phase cooling systems. A simple gas cooling system, such as a compressed air vortex tube may be a preferred cooling means for the inner and/or outer mould.

During operation, the cooling means may be used to continuously coo! the inner and/or outer moulds. Alternatively, the cooling means may be used to cool the inner and/or outer mould only when the microwave generator is not operating to heat a heel counter or toe puff. The cooling means may be used to maintain the inner and/or outer moulds at a low temperature. For example, it may be preferable to maintain the inner and/or outer mould at a temperature less than 10°C during operation of the cooling means.

The microwave generator of^" the present invention may be any suitable generator that can deliver microwave radiation to the space. However, it may be preferabie that the microwave generator comprises a magnetron and an antenna, the magnetron located externally to the heater and the antenna extending into the heater to be positioned within or close to the space. This constructio may be preferred as it minimises the volume taken up within the heater by the microwave generator but stiK ailows the microwave radiation to be precisely delivered to a counter or puff located within the space when the apparatus is used. The precise shape and positioning of the antenna will be dependent upon whether the apparatus is a heel counter heater or a toe puff heater and on the size and dimensions of the heater and space and on other routine design considerations. It is believed that the skilled person wiii be able to determine an appropriate antenna shape and positioning for an apparatus according to the present invention, in order to contain microwave radiation within a heater according to the present Invention it may be advantageous that the heater further comprises an outer faraday cage surrounding the heater to contain microwave radiation. A faraday cage may be formed in any manner and of any material that is apparent to a person skilled in the art,

Preferably, the inner mould of the heater will be formed of a material or materials with suitable properties. In particular, it is advantageous that the inner mould has low microwave absorption, and high mechanical strength. Low microwave absorption ensures that the inner mouid is not significantly heated by the microwaves in the heater. Materials with suitably low microwave absorption include, but are not limited to, PTFE, high density polyethylene (HDPE), alumina, quartz glass, zirconla and titanium dioxide. High mechanical strength is necessary as the material will be compressed during operation of the heater. All of the previously mentioned materials have a suitably high mechanical strength,

The mechanical strength of alumina and zirconia is higher than that of PTFE so in some embodiments of the Invention these materials may be preferred. However, these; materials are expensive so alternative materials with Sower strength may be preferred to reduce cost. in some embodiments of the invention it may be possible to partially or completely form the inner mould from high temperature polymers including, but not limited to, PEEK, Polysulfone (PUS) and Poiyethersulfone (PES), If a high temperature polymer is used then it will be generally preferable for the inner mould to. have a hollow, rather than solid, construction in order to aid thermal dissipation and prevent overheating of the inner mould.

It is also advantageous, although not essential, that the inner mould is formed of a material with a high thermal conductivity. This is because high thermal conductivity allows heat to be efficiently conducted awa from a heel counter or toe puff. A high thermal conductivity may be considered to be a thermal conductivity greater than 2 ννπτ'Κ"¹, a very high thermal conductivity being higher than 20 Wrrr^K^"1-, In some embodiments of the invention it may be possible to use materials with a lower thermal conductivity than this if the inner mould is formed in such a manner that sufficient cooling is st ll possible, A material with a lower thermal conductivity may be used if the heater comprises a very efficient and/or powerful cooling means and the inner mould is formed in such a manner to allow good cooling. For example, a hollow inner mould that is formed to circulate a cooling fluid therein. One material that may be particularly suitable for forming the inner mould is alumina, which has a very high thermal conductivity of approximately 30 Wrn^K^"1 and has a suitably high mechanical strength and a suitably low microwave absorptivity.. However, alumina is an expensive material that is difficult and complex to shape. Generally, the best way to form a mould entirely of alumina would be to use a sintering process, which may result in the mould, and therefore the heater, being excessively expensive, Alternatively, it may be possible to form an alumina. -mould using an injection moulding process and subsequent heat treating. This may result in an alumina mould being less expensive,

An alternative material to use is- quartz glass. This material also has a high strength and low microwave absorptivity. Quartz glass has a high thermal conductivit of approximately 3 Wm K^*1. Quartz glass is generally cheaper and easier to form than alumina but its thermal conductivity Is lower,

A further alternative materia! to use is- HOPE. This material also has a high strength and low microwave absorptivity. HDPE is significantly cheaper and easier to form than either alumina or quartz glass. However, In some embodiments HDPE might not be preferred as it has a low thermal conductivity (0.1 to 0.3 Wnr¹K^"1) and so may be difficult to cool sufficiently.

The inner mould of the present invention may be formed from a single material or it may be formed from a plurality of materiais. If the inner mould is formed from a plurality of materials then different regions of the mould may be formed from different materiais. This may be done to.- reduce cost and/or to form different regions of the inner mould from materials having different and particularly suitable physical properties.

For example, of the materials described above, HDPE is cheap and easy to form but has a relatively low thermal conductivity that makes it difficult to cool, whilst alumina has a high thermal conductivity but is expensive and difficult to form. Therefore, in some embodiments of the invention an inner mould may be formed of both HDPE and alumina such that regions that require significant cooling are formed of alumina and regions which require less or negligible cooling are formed of HDPE. !n this manner a inner mould that is relatively chea and easy to form but also high effective may be provided,

The regions of an inner mould that will require significant cooiing may be those areas that are: directly in contact with a heel counter or toe puff during use of the heater. Similarly, the regions of an inner mould that will require less heating are those areas thai are not directly, in contact with a heel counter or toe puff during use of the heater.. That is. an inner mould of the present invention may be formed of a plurality of materials wherein one or more materials with a high thermal conductivity are used to form regions of the mould that are directly in contact with a heel counter or toe puff during use and one or more materials with a low thermal conductivity are used to form the other regions of the mouid.

The relative thermal properties of HOPE, quartz glass, and alumina have been investigated. An experiment has been carried out to assess the degree to which the materials can be cooled using a vortex tube chiller. In particular, a 24G08tu/h 35cfm pneumatic fold fraction vortex tube was used to chiil a HOPE inner mould, an alumina tube and a quartz glass tube. The temperature of each material was then measured at thirty second intervals to determine the ability of the vortex tube to cool the materials;

As can be cieariy seen, the HOPE mould was not significantly cooled by the vortex tube whilst the alumina and quartz glass tubes were quickly and significantly cooled. As a result, if a vortex tube is used as the cooling means it is not preferable to form the inner mouid entirely from HOPE. Instead the inner mould may be formed entirely of alumina and/or quartz glass or, more preferably, the inner mould may be formed of both HOPE and alumina and/or quartz glass wherein regions that do not require significant cooling are formed of HOPE and regions that require more cooling are formed of alumina and/or quartz glass in the manner set out above, I a similar manner to the inner mould, the outer mould also preferably has a low microwave absorption and a high thermal conductivity. An outer mould of a heater according to the present invention may be formed in any manner in which an inner mould may be formed, as set out above. However, it may be preferable that the outer mould is formed of a flexible materia! in order to allow it to be damped and/or shaped to fit a component that is heated in the heater, in order to fulfil these requirements it may be preferable that the outer mould is formed of natural rubber, synthetic rubber nd/or neopre e.

The outer mould may be substantially solid. Alternatively the outer mould may be inflatable. The benefit of using an inflatable outer mould is that are no shape restrictions on the shape of heel counter or toe puff being moulded and that a more uniform pressure may be applied to the heel counter or toe puff. An inflatable: outer mould may be formed of any suitable material including, but not limited to, the materials set out immediately above. In preferred embodiments an inflatable outer mould may be formed of rubber with a leather jacket. in order to properly contain and guide the microwaves within the heater it may be preferable that the heater comprises a wave guide cavity within which the inner mould and the outer mould are positioned. In order to provide a simple construction the wave guide cavity may be cuboid, A wave guide cavity can be formed in any manner apparent to a person skilled in the art. The wave guide cavity may be multi-mode and supply a plurality of field patterns. However, it is generally preferred that the wave guide cavity supports a minimum possible number of field patterns. In a preferred embodiment the wave guide cavity allows only three field patterns within the cavity. This is preferred because it achieves an extremely high field density in the centre of the cavity while allowing all standard shoe sizes to be accommodated (UK sizes 4- 11 ).. By forming the space of the heater at the centre of the cavity the extremel high field density can be used to heat a heel counter or toe puff.

The microwave generator of the present invention may be operated at an power that is suitable to heat the heel counter or toe puff to the desired temperature. In preferred embodiments of the: invention the power of the microwave generator maybe 600W or higher. Further features of the apparatus of the present invention and its operation wii! he apparent from the description of the method of the present invention, which is set out below. The present invention also provides a method of rapidly heating and cooling a toe puff or a heel counter comprising the steps of;

positioning the heel counter or toe puff in a space defined by an inner mould and an outer mould;

compressing the heei counter or toe puff within the space using the inner mould and the outer mould;

applying microwave radiation to the heei counter or toe puff; and

cooling the toe puff or heel counter whilst still in positio between the inner mould and outer mould;

wherein, the heei counter or toe puff is formed of a material that is susceptibie to microwave heating.

The method of the present invention is advantageous because utilising microwave heating to heat a heei counter or toe puff may be significantly quicker and more efficient than heating using conventional methods. Further, heating using microwave heating ma be much more directed. Additionally, microwave heating of a heei counter or toe puff using the method of the present invention ma result in muc less heating of components adjacent to the heei counter or toe puff, thereby resulting in an increased efficiency of heating. For the present invention to operate appropriately it is necessary that the heel counter or toe puff that is being heated is formed of a material that is suitable for microwave heating. In particular, it is necessary that the materials from which the counters or puffs are formed have a high microwave absorption. Toe puffs and heel counters formed of some such materials are considered to be a separate but related invention and are the subject-matter of a UK patent application 1320420,0 entitled "Toe Puffs and Heel Counters" that was filed by Texon Management Ltd on 19 November 2013, Although it is beneficial to use the materials that are the subject-matter of that application it is to be understood that the method of the present invention can be used with toe puffs and heel counters formed of materials that have previously been used for such components. The skilled person will understand, or wii! be- easily able to determine by routine experimentation, which materials are suitable for use with the method of the present invention. Microwave absorption within a. material is primarily determined by the dielectric loss, tangent (tan^'S). of the material. -The minimum suitable dielectric loss tangent for efficient heating in the method and apparatus of the present invention is 0,05, Materials with dielectric loss tangents lower than this are generally not suitable for forming a heel counter or toe puff using the apparatus or method of the present invention.

The temperature to which a heel counter or toe puff is heated will be determined by the material from which the item is formed. The appropriate or necessary temperature to which a counter -or puff is heated should be able to be easily determined by a person skilled in the art. Generally it is anticipated that a heel counter or toe puff heated using the method of the present invention will be heated to a temperature between 80°C and 90°C.

The time required to heat a heel counter or toe puff will depend on the ambient temperature, the material of the counter o puff, the temperature to which it is necessar to heat the counter or puff and the intensit of the microwave radiation provided. However, it is believed that in most embodiments of the invention it -Will be necessary to heat a heel counter or toe puff for between 1s and 15s and more preferably 3s and 7s, The method of the present invention further comprises the step of cooling the toe puff or heel counter after heating whilst still in position between the inner mould and the outer mould. That is, the method of the present invention comprises a step where action is taken to cool the heel counter or toe puff whilst the counter or puff is in-situ within the heater, rather than simply allowing the toe puff or heel counter to cool as an incidental side-effect during any further processing or moving the heel counter or toe puff to a cooling station and then cooling the counter or puff, as is currentl done in methods according to the prior art that use conventionai heaters. The cooling step takes place whilst the heel counter or toe puff remain in position within the space defined by the inner mould and the outer .mould. This can be done by removing or stopping any microwave heating and providing cooling by conduction t rough the inner mould and outer mould, This was not possible in methods according to the prior art as the inner mould and outer mould were: used to heat the heel counter or toe puff using conductive heating and, as a result, were held at or above the intended maximum temperature of the heel counter or toe puff. Therefore, previously in order- to eool the heel counter or toe puff it was essential to remove the heated item from the inner mould and outer mould.

Cooling whilst in position within the space may be made possible by the method of the present invention for a number of reasons. First, microwave heating may be directed only to the heel counter or toe puff and it is not necessary to heat the inner mould or the outer mould, Second, the inner mould and outer mould may be formed of materials that are not susceptible to microwave heating, meaning that even if they are exposed to microwaves they will not heat up substantiaily and will act to cool the heel counter or toe puff. Thirdly, as the inner mould and outer mould are not significantly heated {other than by conduction from the heel counter or toe puff) it is possible to actively coo! the inner mould and/or outer mould in orde that they can provide better cooling, Cooling of the inner mould and/or outer mould may be carried out in any manner apparent to the person skilled in the art and will depend on the materials and construction of each mou!d:..

If the inner mould and/or outer mould are cooled it may be beneficial to maintain them at a temperature that will actively cool the heel counter or toe puff at all times. That is, it may be preferable that the inner and/or outer moulds are maintained at a temperature below normal room temperature. For example, it may be preferable that the inner and/or outer mould are maintained at a temperature of 1G°C or less. This will allow more effective cooling: of the heel counter or toe puff to or near room temperature after heating has finished. Alternatively, the cooling of the inner and/or outer mould may only take place after the microwave heating of the heel counter or toe puff has taken place,. Generally, after heating, It will be preferable to cool a heel counter or toe puff to a temperature between 10°C to 30°C and most preferably about 2G^f)C, As will be generally appreciated, the time taken to achieve this cooling may depend on a variety of factors including, but not limited to, the ambient temperature, the materia! of the heel counter or toe puff, and whether the inner and outer moulds are cooled and the temperature to which the item was heated. However, in preferred embodiments of the invention it will generally be preferable to cool a heel counter or toe puff for between 10s and 30s, Microwave radiation may be provided or applied in any suitable manner, in preferred embodiments the radiation may be produced by a magnetron with an antenna extending into a suitable region in order to suitably direct the microwaves to heat the heel counter or toe puff. A magnetron with a power between 400W and TOOOW and, more preferably between 600W and 8G0W, will generally be sufficient for the method of the present invention.

As an example, a preferred embodiment of the method of the present invention will be carried out as follows. A heel counter or toe puff will be positioned in the space defined by an inner mould and an outer mould, wherein the inner and outer mould are cooled to a temperature of approxjmateiy 5°C, The heei counter will then be compressed using the Inner mould and the outer mould in order to form the heel counter into a suitable shape. The heel counter or toe puff will then be heated to a temperature of approximately 80^DC using microwave heating f om: a 70GW magnetron for about 5s. The heating will then be stopped and the heel counter or toe puff will be held within the space for 25s to coo! the counter to approximately 20°C under the action of the cooled inner mould and outer mould. The heel counter or toe puff will then be removed from the heater.

Any suitable apparatus may be used for carrying out the method of the present invention. However, it may be generally preferable to use the apparatus of the present invention, as described above, to carry out the method. Further any Individual feature of the apparatus of the present invention may be used in isolation or in combination to implement the method of the present invention, except where it would be impractical or impossible to do so. Further it is to be understood that the method of the present invention may be used to heat a heel counter or toe puff whilst it is attached to other components of a piece of footwear, for example shoe linings and uppers.

The apparatus and method of the present invention may be better understood from the preferred embodiment that is shown in the drawings and Is described below.

Drawings

Figure: 1 is a schematic diagram of a preferred embodiment of the apparatus of the present invention;

Figure 2 is a graph showing the heating of a heel counter using the method and apparatus of the present invention: and

Figure 3 is a graph showing the heating of the same heel counter using the method of the prior art, A heel counter heater 1 according to the apparatus of the present invention is schematica!iy represented In Figure 1. The heater 1 comprises an inner mould 2, an outer mould 3, a magnetron (not shown) a magnetron antenna 4, a faraday cage 5 and a space 8 defined by the inner mould and the outer mould, The inner mould 2 is formed of alumina and HOPE and during use is maintained at a temperature of 5°C using a first cooling means (not shown). The outer mould 3 is formed of neoprene and is maintained at a temperature of 5°C using a second cooling means (not shown). The magnetron antenna 4 is positioned to provide high density and approximately uniform heating within the space 6. The magnetron has a power of 700W. The faraday cage 5 acts to contain microwaves within the heater 1 during operation of the magnetron. The heater 1 is sized and shaped such that it allows only three modes within the cavity defined by the heater for the microwaves generated by the magnetron and emitted from the antenna 4,. The space 6 has an appropriate shape to mould a heel counter 7 during operation of the heater 1 .

The inner mould 2 is formed such that the regions of the mould that: are in contact with a heel counter 7 during operation of the heater 1 are formed of alumina, with the remainder of the inner mouid 2 being formed of HUP^'E, The first cooling means of the heater 1 is a 2400Btu h 35cfm pneumatic cold fraction vortex tube:. The heater 1 may be operated according to the method of the present invention in the following manner. First, the outer mould 3 is separated from the inner mould- 2 such that a heel counter 7 and the components to which it is attached, for example an upper lining and an upper formed of synthetic leather, may be positioned appropriately, The heel counter 7 is then placed in the appropriate position and the outer mould 3 is repositioned relative to the inner mould 2 such that the space 6 appropriately constrains the heel counter 7, The magnetron is then turned on and the heel counter 7 is heated for a period of 5s. The magnetron Is then turned off and the heel counter 7 is retained within the space 6 and cooled by the action of the cooled inner mould 2 and outer mould 3 for a period of 25s. After the cooling period the outer mould is again separated from the inner mould 2 and the hee! counter 7 is removed from: the heater 1. The process: may then be repeated for further hee! counters 7. The heating and subsequent cooling of a heel counter 7 and the components to which it is attached using the apparatus of Figure 1 over the 30s cycle set out above is illustrated in Figure 2, The heel counter 7 used in this 30s cycle weighs approximateiy 13.5g and is formed of a mixture of TPU, PM A and carbon black. This material is particularly suitable for microwave heating. The heel counter 7 is attached to an upper !injng and an upper synthetic leather, each formed of conventional materials and which together weigh 25g.

As can be seen clearl in Figure 2 the inner and outer moulds 2, 3 are maintained at a temperature of approximateiy 5°C throughout the heating and cooling cycle. The microwave heating of the heel counter 7 raises the temperature of the counter from 20^QC at 0s to SQ^OC at about 6s. in contrast, the upper lining only reaches a maximum temperature of 40°C and the upper synthetic leather only reaches a maximum temperature of about 33°C. This is mainly because these components are formed of materials that are not as susceptible to microwave heating as the heel counter 7, After 30s the heel counter is at a temperature of about T9°C and the upper lining and the upper synthetic leather are both at temperatures below 22°C and, as a result, further processing can be carried out immediately. It is noted that in this specific example the upper is formed of synthetic leather. However, the apparatus and method of the present invention are also suitable for footwear having uppers formed of other materials including, but not limited to, natural leather, In experiments where the upper was formed of natural, rather than synthetic, leather but that were otherwise identical the natural leather upper is heated to a peak temperature of about 8°C in the time taken to raise the counter to 9G°G.

Figure 3 shows the heating and cooling of the same heel counter 7 over a 80s cycle using a method according to the prior art. This heater used for this method was substantially the same as the heater 1 of Figure 1 with the exception that it does not comprise a magnetron, magnetron antenna 4 or faraday cage 5. Further, the inner mould comprises heating means for raising the temperature of the inner mould and the inner mould is formed of a conventional thermally conductive mould material. In the method shown in Figure 3 the heel counter 7 is heated when positioned in the heater using a heated inner mould 2 that Is heated to 120°C. Heating is carried out for 3Gs. Cooling is earrted out by cooling the inner mould 2 to 10°C whilst the heel counter 7 remains in position and is also carried out for 30s. During the heating and cooling the outer mould is maintained at 20°C,

The temperatures of the various components is illustrated in Figure 3. The heel counter 7 is heated to a maximum temperature of about 65°C, after about 32s, it is then cooled back down to 34°C, at 60s. The upper lining reaches a maximum temperature of more than 100°C and is cooled: to below 20°C. The upper synthetic leather is only cooled to 40°C but is also only cooled to about 36°C, at 60s.

Compared to the method of Figure 2, the method of Figure 3 has a number of disadvantages. First, at the end of a 60s cycle the heel counter 7 and upper synthetic leather remain significantly above their initial temperature of 2G^QC, which ca hinder further processing. Additionally, the upper lining is heated to above 10Q°C, which is undesirable but is an inevitable outcome of the conductive heating, A further, and very significant disadvantage of the method of Figure 3 is that a single heating and cooling .cycle: akes 60s, which is. twice the duratio of the heating and cooling cycle according to the present invention shown in Figure 2. Finally, the method of Figure 3 does not heat the heel counter 7 to the same maximum temperature as the method of Figure 2, which can lead to poorer forming of the heel counter 7.

Claims

Claims.

1. A heel counter and/or toe puff heater comprising:

an inner mould;

an outer mould;

a s ace defined by the inner mould and the outer mould thai is sized to contain and constrain an appropriate part of a piece of footwear;

a microwave generator that, when i use, directs microwave radiation to the space; and

cooling means for the cooling the inner mould and/or cooling means for cooling the outer mould,

2. A heater according to any preceding claim wherein the microwave generator comprises a magnetro and an antenna, the magnetron located externaiiy to the space and the antenna extending into the space.

3. A heater according to any preceding claim further comprising an outer faraday cage surrounding the heater to contain microwave radiation.

4. A heater according to any preceding claim, wherein the inner mould is entirely formed of an Incompressible material with a thermal conductivity greater than 2 Wnv ^K ,. and preferably greater than 20 Wm^*1K , 5. A heater according to: claim 4 wherein the inner mould is entirely formed of alumina or quartz glass.

6. A heater according to any of claims 1 to 3 wherein the inner mould is entirely formed of a low thermal conductivity polymer.

7. A heater according to any of claims 1 to 3_:, wherein the inner mould comprises regions formed of materials with a thermal conductivity greater than 2 Wnr¹K^'1, and preferably greater than 20 Wnr¹K^~1, and regions formed of a low_: thermal conductivity polymer.

8. A heater according to claim 7, wherein the regions formed: of materials with a thermal, conductivity greater than 2.Wm^~1K^*1, and preferably greater than 20 Wrrr^{1 "1'}, are in contact with a heel counter or toe puff during use of the heater and the regions formed of the low thermal conductivity polymer are not in contact with a heel counter or toe puff during use of the healer.

9. A heater according to any of claims 6 to 8, wherein the low thermal conductivity polymer is HDPE.

10. A heater according to any of claims 6 to 9,. wherein the materials with a thermal conductivity greater than 2 Wnr^{1 '1}, and preferably greater than 20 Wnr' ^"', are alumina and/or quartz glass. 1 , A heater according to any preceding claim wherein the outer mould is formed of a flexible material,

12. A heater according to eiaim 11 , wherein the outer mould is formed of rubber and/or neoprene,

13. A heater according to any preceding claim, comprising a rectangular wave guide cavity, within which the inner mould and outer mould are positioned,

14. A heater according to claim 13 wherein the wave guide cavity supports three or less modes within the cavity,

15. A heater according to any preceding claim wherein the microwave generator has a power of 800VV or higher. 6. A method of rapidly heating and cooling a toe puff or a heel counter comprising the steps of.

positioning the heel counter o toe puff in a space defined by an inner mould and an outer mould; pressing the heel counter or toe puff between the inner mould and the outer mould;.

applying microwave radiation to the heel counter or toe puff;

wherein, the heei counter or toe puff is formed of a material that is susceptible to m icro wave h ea tin g ;

cooling the toe puff or heei counter after heating whilst still in position between the inner mould and outer mould,

17. A method according to claim 16, wherein the toe puff or heei counter is cooled to a temperature between 1 G°C to 30°C,

18, A method according to ciaim 16 or 17, wherein the toe puff or heel counter is cooled for between 15s and 60s. 19. A method according to any of claims 16 to 18 wherein during the method the inner mould and outer mould are maintained at a temperature of 10°C or less,

20. A method according to any of claims 16 to 19 wherein the heei counter or toe puff is heated to a temperature between 70^DC to 90°C.

21 , A method according to any of claims 16 to_: 20 wherein the heel counter or toe puff is heated for between 1s and 5s.

22. A method according to any of claims 16 to 21 wherein the heel counter or toe puff is heated and cooled using a heater according to any of claims 1 to 15.