Variable pressure shoe last and method for bonding sole and upper by variable pressure injection molding

Abstract

A variable pressure shoe last and a method for bonding a sole and an upper by variable pressure injection molding are provided. The variable pressure shoe last includes a shoe last body and a variable pressure porous module. The variable pressure porous module is embedded in the shoe last body and correspondingly exposed in a foaming molding space. The method of bonding the sole and the upper by variable pressure injection molding includes providing the variable pressure shoe last, placing the upper onto the variable pressure shoe last, injecting a foaming material and performing a bonding step. Therefore, the upper can be tightly bonded to the sole, which is formed after the complete foaming of the foaming material, without the use of an adhesive.

Description

Technical Field

[0001] This invention relates to a method for combining a shoe last and a sole with an upper, and more particularly to a method for combining a variable pressure shoe last and a variable pressure injection-molded sole with an upper. Prior Technology

[0002] Shoes are primarily used to protect the feet from being injured by sharp objects when stepping on the ground. Shoes typically consist of an upper and a sole. The upper can be made of any suitable material to cover, secure, and support the foot to the sole structure. The sole is usually an extension between the upper and the ground surface, providing abrasion resistance and traction, as well as cushioning to avoid the impact when the foot contacts the ground.

[0003] In shoe manufacturing, the bonding of the upper and sole directly affects the shoe's durability and comfort. In conventional processes, the bonding process begins by ensuring the materials of both the upper and sole are clean. Adhesive is then evenly applied to the contact surfaces of the upper and sole, and allowed to dry slightly to achieve optimal adhesion. Once the adhesive reaches the appropriate viscosity, the upper and sole are precisely aligned and bonded together. A press or other tool is then used to apply pressure, ensuring a tight fit without air bubbles or gaps. In some cases, heating may be necessary to enhance the adhesive's effectiveness and increase bond strength, ensuring a more secure bond between the upper and sole. Finally, the shoes are allowed to cool naturally and the adhesive is allowed to fully cure, the specific time depending on the type of adhesive and the application conditions.

[0004] However, because the uppers and soles are made of different materials, and these dissimilar materials vary in their elasticity, hardness, and density, conventional shoes often suffer from poor lifespan, easy damage, and soles that easily detach from the uppers. Furthermore, the volatile organic compounds commonly used in the gluing process during the bonding of the uppers and soles can easily cause harm to human health and the environment. Therefore, developing a method to tightly bond the uppers and soles without the need for adhesives is a commercially viable development goal. Summary of the Invention

[0005] One embodiment of the present invention provides a variable pressure shoe last, comprising a shoe last body and a variable pressure porous mold. The variable pressure porous mold is embedded in the shoe last body and correspondingly exposed in a foaming molding space. The variable pressure porous mold has a plurality of variable pressure pores, which are connected to the foaming molding space.

[0006] Based on the aforementioned variable pressure shoe last, it may further include an air chamber, which is opened in the shoe last body and corresponds to the variable pressure porous module.

[0007] Based on the aforementioned variable pressure shoe last, it may further include a plurality of gas channels, one end of each gas channel being connected to the variable pressure porous module, and the other end of each gas channel being open outward and having an air vent on one surface of the shoe last body.

[0008] According to the aforementioned variable pressure shoe last, the shoe last body includes a clamp and a last head body, with the clamp connected to the top of one of the last head bodies.

[0009] According to the aforementioned variable pressure shoe last, the last body includes a shoe toe and a shoe heel, with the shoe toe detachably connected to the shoe heel.

[0010] Based on the aforementioned variable pressure shoe last, it may further include a gating system that penetrates the shoe last body, and the gating system has a gate on one side of the shoe last body near the foaming molding space.

[0011] Based on the aforementioned variable pressure shoe last, the size of each variable pressure pore in the variable pressure porous mold is 30 micrometers to 300 micrometers.

[0012] Another embodiment of the present invention provides a method for bonding a variable pressure injection molded sole to a shoe upper, comprising the following steps: providing a variable pressure shoe last as described above; fitting a shoe upper into the variable pressure shoe last and positioning it in an injection molding system; injecting a foaming material into a foaming space of the injection molding system; performing a bonding step by applying pressure to the foaming material and heating the foaming material to foam into a sole, wherein the sole and the shoe upper are bonded together to obtain a shoe.

[0013] According to the aforementioned method of combining a variable pressure injection sole with an upper, the upper has a bottom layer, and the bottom layer has a plurality of evenly distributed holes, each hole having a size of 0.1 mm to 3 mm.

[0014] According to the aforementioned method of combining the variable pressure injection sole with the upper, the upper has a bottom layer, and one of the materials of the bottom layer is a fabric.

[0015] Therefore, the variable pressure shoe last of the present invention utilizes the setting of variable pressure porous mold and is combined with the variable pressure injection shoe sole bonding method of the present invention. By controlling the pressure, the foam material can penetrate into the bottom layer of the shoe upper, or the foam material near one end may have incompletely foamed air bubbles and micropores. This results in a roughening effect on the contact surface between the foam material and the shoe upper, thereby allowing the shoe upper and the shoe sole formed after the foam material is fully foamed to be tightly bonded without the need for adhesive. Simple Explanation of the Diagram

[0016] To make the above and other objects, features, advantages and embodiments of the present invention more apparent and understandable, the accompanying drawings are described below: Figure 1 illustrates a three-dimensional structural diagram of a variable-pressure shoe last according to one embodiment of the present invention; Figure 2 shows a cross-sectional view of the variable compression shoe last along section line 2-2 according to the embodiment in Figure 1; Figure 3 shows a bottom view of the variable compression shoe last according to the embodiment in Figure 1; Figure 4 illustrates a three-dimensional structural diagram of a variable-pressure shoe last according to another embodiment of one of the present invention; Figure 5A shows an exploded view of the variable pressure shoe last according to the embodiment in Figure 4; Figure 5B shows an exploded view of the variable compression shoe last according to the embodiment in Figure 4 from another perspective; Figure 6 shows a cross-sectional view of the variable compression shoe last according to the embodiment in Figure 4 along section line 6-6; Figure 7 shows a bottom view of the variable compression shoe last according to the embodiment in Figure 4; Figure 8 illustrates a flowchart of the steps of a method for bonding a variable pressure injection molding sole to a shoe upper according to another embodiment of the present invention; Figure 9A illustrates a process for bonding a sole to an upper using the variable-pressure injection molding method of the variable-pressure last in the embodiment of Figure 1; and Figure 9B illustrates a process of using the variable-pressure last of the embodiment in Figure 4 to perform variable-pressure injection molding of the sole and upper. Implementation

[0017] Several embodiments of the present invention will now be described with reference to the drawings. For clarity, many practical details will be described in the following description. However, it should be understood that these practical details are not intended to limit the invention. That is, in some embodiments of the invention, these practical details are not essential. Furthermore, for the sake of simplicity, some conventional structures and elements will be shown in the drawings in a simple schematic manner.

[0018] It should be noted that certain terms in the specification and claims of this invention are preceded by "first", "second", "third" or "fourth" to distinguish them from each other. Unless otherwise specified, or if the order of the terms is not apparent from the context, the order of the terms is not restricted by the prefixes "first", "second", "third" or "fourth".

[0019] Please refer to Figures 1 through 3. Figure 1 shows a three-dimensional structural schematic diagram of the variable-pressure shoe last 100 according to one embodiment of the present invention. Figure 2 shows a cross-sectional schematic diagram of the variable-pressure shoe last 100 according to the embodiment of Figure 1 along section line 2-2. Figure 3 shows a bottom view of the variable-pressure shoe last 100 according to the embodiment of Figure 1. The variable-pressure shoe last 100 includes a shoe last body 200 and a variable-pressure porous module 300. The variable-pressure porous module 300 is embedded in the shoe last body 200 and correspondingly exposed in a foaming molding space (not shown).

[0020] The shoe last body 200 includes an air chamber 201, which is formed in the shoe last body 200 and corresponds to the variable pressure porous mold 300, so that both sides of the variable pressure porous mold 300 have the same attractive force. Furthermore, the shoe last body 200 includes a plurality of gas channels 203, one end of each gas channel 203 is connected to the variable pressure porous mold 300, and the other end of each gas channel 203 is open outward and has an air vent 202 on one surface of the shoe last body 200. By using the variable pressure porous mold 300 in conjunction with the air chamber 201 and gas channels 203 of the shoe last body 200, the gas and pressure changes in the injection molding system equipped with the variable pressure shoe last 100 can be directionally controlled. The shoe last body 200 may include a clamp 210 and a last body 220. The clamp 210 is connected to the top of one of the last bodies 220, and the clamp 210 is detachably connected to the last body 220.

[0021] The variable pressure porous mold 300 has a plurality of variable pressure pores 301, which connect to a foaming molding space. This foaming molding space is the space in the injection molding system where foamed material is heated and expanded to form the molded product. The variable pressure pores 301 of the variable pressure porous mold 300 are manufactured using metallurgical methods and are distributed in a non-equidistant mesh pattern or arranged in equidistant parallel patterns. The size of the variable pressure pores 301 in the variable pressure porous mold 300 can be from 30 micrometers (µm) to 300 micrometers; preferably, the size of the variable pressure pores 301 can be from 100 micrometers to 250 micrometers. Furthermore, a cooling pipe (not shown) can be embedded within the variable pressure porous mold 300 to allow cooling fluid to pass through. As shown in Figures 1 to 3, the variable pressure shoe last 100 includes a variable pressure porous module 300, and the variable pressure porous module 300 is embedded in the bottom of the shoe last body 200. However, the number and position of the variable pressure porous module 300 are not limited thereto. Multiple variable pressure porous modules 300 can be set according to actual needs, or the variable pressure porous module 300 can be embedded in other positions of the shoe last body 200 exposed in the foaming molding space.

[0022] Please refer to Figures 4 through 7. Figure 4 shows a three-dimensional structural schematic diagram of the variable-pressure shoe last 400 according to another embodiment of one of the present invention. Figure 5A shows an exploded view of the variable-pressure shoe last 400 according to the embodiment of Figure 4. Figure 5B shows an exploded view of the variable-pressure shoe last 400 according to another perspective according to the embodiment of Figure 4. Figure 6 shows a cross-sectional schematic diagram of the variable-pressure shoe last 400 according to the embodiment of Figure 4 along section line 6-6. Figure 7 shows a bottom view of the variable-pressure shoe last 400 according to the embodiment of Figure 4. The variable-pressure shoe last 400 includes a shoe last body 500 and two variable-pressure porous molds 600. The variable-pressure porous molds 600 are embedded in the shoe last body 500 and correspondingly exposed in a foaming molding space.

[0023] The shoe last body 500 includes an air chamber 501, which is formed in the shoe last body 500 and corresponds to one of the pressure-changing porous modules 600. Furthermore, the shoe last body 500 includes a plurality of gas channels 503, one end of each gas channel 503 being connected to the pressure-changing porous module 600, and the other end of each gas channel 503 opening outwards and having an air vent 502 on one surface of the shoe last body 500. The shoe last body 500 may include a clamp 510 and a last body 520, the clamp 510 being connected to the top of one of the last bodies 520, and the clamp 510 being detachably connected to the last body 520. The last body 520 includes a toe section 530 and a heel section 540, the toe section 530 being detachably connected to the heel section 540 to form the last body 520. The top of the shoe toe 530 has a protrusion 531, and the bottom of the clamp 510 has a groove of the corresponding shape of the protrusion 531, thereby allowing the clamp 510 to engage with the last body 520. Furthermore, the shoe last body 500 includes a gating system 504 that penetrates the shoe last body 500. The gating system 504 has a gate 505 on one side of the shoe last body 500 near the foaming molding space (not shown), allowing foam material to enter the foaming molding space through the gating system 504. The number and location of the gating systems 504 are not limited thereto; multiple gating systems 504 can be provided as needed to allow for the injection of at least two different foam materials, or for the same foam material to undergo at least two different types of treatment.

[0024] The variable pressure porous module 600 has a plurality of variable pressure pores 601, which connect to the foaming molding space. The size of the variable pressure pores 601 in the variable pressure porous module 600 can be from 30 micrometers to 300 micrometers, preferably from 100 micrometers to 250 micrometers. As shown in Figures 4 to 7, the variable pressure shoe last 400 includes two variable pressure porous modules 600, which are respectively embedded in the bottom of the toe 530 and the bottom of the heel 540. However, the number and position of the variable pressure porous modules 600 are not limited thereto. Multiple variable pressure porous modules 600 can be set as needed, or the variable pressure porous modules 600 can be embedded in other positions of the shoe last body 500 exposed in the foaming molding space.

[0025] Please refer to Figures 8 and 9A. Figure 8 illustrates a flowchart of the steps of a method 700 for bonding a sole and upper using variable pressure injection molding according to another embodiment of the present invention. Figure 9A illustrates a schematic diagram of the process of the method 700 for bonding a sole and upper using the variable pressure last 100 of the embodiment in Figure 1. The method 700 for bonding a sole and upper using variable pressure injection molding includes steps 710, 720, 730, and 740.

[0026] Step 710 is to provide the aforementioned variable pressure shoe last, for example, variable pressure shoe last 100.

[0027] Step 720 involves fitting a shoe upper 910 into a variable-pressure shoe last 100 and positioning it within an injection molding system 800. The injection molding system 800 includes a first side mold 810, a second side mold 820, a movable lower mold 830, and the variable-pressure shoe last 100. The first side mold 810, the second side mold 820, the movable lower mold 830, and the variable-pressure shoe last 100 can open or close the foaming molding space 801. The second side mold 820 has a gating system 811 through which foamed material enters the foaming molding space 801, and the foaming molding space 801, when closed, corresponds to the shape of the sole 930. The upper 910 has a bottom layer, which is the contact area between the upper 910 and the sole 930. The bottom layer can be made of leather, synthetic leather, suede, nylon, or neoprene. The bottom layer of the upper 910 has a plurality of evenly distributed holes, each hole having a size of 0.1 mm to 3 mm. Furthermore, the bottom layer of the upper 910 can be made of a fabric, which can be knitted or plain weave.

[0028] Step 730 involves injecting a foaming material 920 into the foaming space 801 of the injection molding system 800 through the gating system 811. The foaming material 920 can be a thermoplastic material, such as thermoplastic polyurethane (TPU), thermoplastic polyester elastomer (TPEE), or polyether block amide (PEBAX).

[0029] Step 740 involves a bonding step, in which pressure is applied to the foaming material 920 and the foaming material 920 is heated to foam into a sole 930, which is then bonded to the upper 910 to form a shoe. The pressure in this bonding step can be a fixed pressure or a variable pressure. When the pressure is fixed, the foaming material 920 foams stably, and during the foaming process, it penetrates into the bottom layer of the upper 910, allowing the sole 930 to bond tightly to the upper 910 once foaming is complete. When the pressure is variable, a first pressure is applied for 1 to 5 seconds and then increased to a second pressure, where the first pressure is less than the second pressure; or a third pressure is applied for 1 to 5 seconds and then decreased to a fourth pressure, where the third pressure is greater than the fourth pressure. Preferably, the first pressure can be 5 bar to 30 bar, the second pressure can be 10 bar to 90 bar, for example, after applying a first pressure of 5 bar for 1 to 5 seconds, the second pressure is increased to 60 bar. The third pressure can be 10 bar to 90 bar, and the fourth pressure can be 5 bar to 30 bar, for example, after applying a third pressure of 30 bar for 1 to 5 seconds, the fourth pressure is reduced to 5 bar. When the applied pressure is variable, it affects the foaming degree of the foaming material 920, which can range from 30% to 80%. This results in incompletely foamed air bubbles and micropores at the end of the foaming material 920 near the variable pressure porous mold 300. This roughens the contact surface between the foaming material 920 and the upper 910, allowing it to embed into the pores of the bottom layer of the upper 910 or into the fabric of the bottom layer of the upper 910, achieving excellent adhesion. This allows the upper 910 and the sole 930, formed after the foaming material 920 is fully foamed, to be tightly bonded without the need for adhesives, thus obtaining the shoe. The tensile strength between the upper 910 and the sole 930 can reach 3 kg to 10 kg, indicating a very strong bond between them.

[0030] Once the shoe is finished, the clamp 210 of the variable pressure shoe last 100 can be removed first, and then the last body 220 can be removed, so that the finished shoe can be easily demolded from the variable pressure shoe last 100.

[0031] Please refer to Figure 9B, which illustrates a process diagram of a method 700 for injection molding a sole and upper using the variable-pressure last 400 of the embodiment in Figure 4. The injection molding system 800 used includes a first side mold 840, a second side mold 850, a movable lower mold 860, and the variable-pressure last 400. The first side mold 840, the second side mold 850, the movable lower mold 860, and the variable-pressure last 400 can open or close the foaming molding space 801. The method 700 for injection molding a sole and upper in Figure 9B is similar to the method 700 for injection molding a sole and upper in Figure 9A. The similarities will not be repeated. The difference is that the variable-pressure last 400 includes a gating system 504, from which foam material 920 can be directly injected into the foaming molding space 801. Once the shoe is finished, the clamp 510 of the pressure last 400 can be removed first, then the heel 540 can be removed, and finally the toe 530 can be removed, making it easy to demold the finished shoe from the pressure last 400.

[0032] In addition, please refer to Table 1 below, which is an analysis of the power consumption of each process in the sole molding process in the present invention's variable pressure injection sole bonding upper and conventional shoe manufacturing process. IP (injection phylon) is the conventional sole manufacturing process by injection molding, and CMP (compression molding process) is the conventional sole manufacturing process by compression molding.

[0033] Table 1 process Station Number Statistics period (hours) Electricity consumption (kW) Average electricity consumption (kWh) Electricity consumption per pair produced This invention 12 1 108 7.2 0.24-0.48 IP 8 20 4000 200 Undefined CMP 8 20 4000+3000 200+150 Undefined Traditional assembly line 1300 pairs 7.5 1500 200 1.15

[0034] The average power consumption in Table 1 is based on data from the recorded machine's production, and is calculated based on the equipment's continuous hourly operation or production. The power consumption calculations for IP and CMP do not include pre-processing such as raw material mixing, and IP and CMP do not include post-processing such as molding stabilization and curing. Since the molding steps of the two conventional shoe sole manufacturing processes, IP and CMP, are numerous and lengthy, the power consumption per pair produced needs to be defined. The results in Table 1 show that the variable pressure injection molding method for combining shoe soles and uppers of this invention can significantly reduce the power consumption per pair of shoes produced and can significantly shorten the manufacturing time.

[0035] As can be seen from the above embodiments, the variable pressure shoe last of the present invention utilizes the setting of a variable pressure porous mold, and combined with the variable pressure injection molding method of the present invention for bonding the sole and the upper, it can control the pressure to allow the foamed material to penetrate into the bottom layer of the upper, or to have incompletely foamed air bubbles and micropores at one end of the foamed material, so that the contact surface between the foamed material and the upper has a roughening effect, and is embedded in the holes of the bottom layer of the upper or embedded in the fabric of the bottom layer of the upper, so that the upper and the sole after the foamed material is fully foamed can be tightly bonded without the need for adhesive. Moreover, the joint between the sole and the upper after the foamed material is fully foamed is flat and beautiful, so that the finished shoe has a one-piece molding effect, and can effectively save production costs. Therefore, the present invention can solve the complex process of multiple injections in conventional shoe manufacturing and eliminate the environmentally invasive adhesive materials, thereby reducing the manufacturing cost of the sole and shortening the manufacturing time.

[0036] Although the present invention has been disclosed above by way of embodiments, it is not intended to limit the present invention. Any person skilled in the art can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

[0037] 100, 400: Transformer shoe last 200,500: shoe last body 201,501: Air chamber 202,502: Air inlet 203,503: Gas flow channel 210,510: Clamping seat 220,520: Last Body 300, 600: Transformer multi-hole module 301, 601: Transformer porosity 504,811: Sprue 505: Gate 530: Shoe Toe 531:convex part 540: Heel section 700: Method of bonding the sole and upper using variable pressure injection molding 710, 720, 730, 740: Steps 800: Injection Molding System 801: Foaming Molding Space 810, 840: First side mold 820, 850: Second side mold 830, 860: Lower mold 910: Shoe Upper 920: Foaming material 930: Shoe sole

Claims

1. A variable-pressure shoe last, comprising: a shoe last body; and a variable-pressure porous mold, embedded in the shoe last body and correspondingly exposed in a foaming molding space, the variable-pressure porous mold having a plurality of variable-pressure pores communicating with the foaming molding space; wherein... The variable pressure shoe last further includes a gating system that runs through the shoe last body, and the gating system has a gate on one side of the shoe last body near the foaming molding space.

2. The variable pressure shoe last as described in claim 1 further includes an air chamber formed in the shoe last body and corresponding to the variable pressure porous module.

3. The variable pressure shoe last as described in claim 1 further comprises a plurality of gas channels, one end of each of the gas channels being connected to the variable pressure porous module, and the other end of each of the gas channels being open outward and having an air vent on one surface of the shoe last body.

4. The variable pressure shoe last as described in claim 1, wherein the shoe last body includes a clamp and a last body, the clamp being connected to one end of the last body.

5. The variable pressure shoe last as described in claim 4, wherein the last body includes a toe section and a heel section, the toe section being detachably connected to the heel section.

6. A variable pressure shoe last, comprising: a shoe last body; and a variable pressure porous module, embedded in the shoe last body and correspondingly exposed in a foaming molding space, the variable pressure porous module having a plurality of variable pressure pores communicating with the foaming molding space, wherein each of the variable pressure pores of the variable pressure porous module has a size of 30 micrometers to 300 micrometers.

7. A method for bonding a variable pressure injection molded sole to an upper, comprising: providing a variable pressure last as described in any one of claims 1 to 6; fitting an upper into the variable pressure last and positioning it in an injection molding system; injecting a foam material into a foaming space of the injection molding system; and performing a bonding step by applying pressure to the foam material and heating the foam material to foam it into a sole, the pressure being a variable pressure, and the sole being bonded to the upper, wherein the variable pressure pores of the variable pressure porous mold roughen a contact surface between the foam material and the upper to obtain a shoe.

8. The method of combining a variable pressure injection sole with an upper as described in claim 7, wherein the upper has a base layer and the base layer has a plurality of evenly distributed holes, each of the holes having a size of 0.1 mm to 3 mm.

9. The method of combining a variable pressure injection sole with an upper as described in claim 7, wherein the upper has a bottom layer, and one of the materials of the bottom layer is a fabric.

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