JPS6315906A - Method and mold for producing injection molding shoes havingjunction function in shoe sole - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing injection molded shoes having a shank function in the sole and a mold for molding the same.

More specifically, the object is to provide an injection molded shoe that exhibits the same effect as using a shank material for the sole without using a different shank material for the sole.

[Prior Art] A conventional method for fixing the sole of a shoe to prevent foot fatigue is to use a shank material made of steel, hard plastic, wood, bamboo, etc. as the sole material that forms the sole. The methods used include embedding the shank material into the inner sole, attaching it to one of the inner sole or the outsole by caulking it with rivets or eyelets, or driving it into a predetermined position on the inner sole or the outer sole.

[Problems to be Solved by the Invention] The conventional techniques described above have the following problems, for example.

(1) Positioning, embedding, or attaching the shank material to the bottom material or midsole requires extra man-hours, and the shank material is also expensive, which causes high costs.

(2) It is difficult to reduce the weight. Steel shank materials, which are particularly frequently used, are heavy compared to the weight of the bottom material.

(3) Shank materials made of wood or bamboo may be damaged or broken due to sudden impact when worn, resulting in a state where the shank does not function properly.

(4) When integrally molding the shank material into the sole by injection molding, it is difficult to position the shank material, and special devices and equipment are required for the injection molding machine for this positioning. As an example of this, in JP-A-56-166806,
An injection molding method has been disclosed in which the insert is held in a molding cavity and the insert is integrally molded inside the sole of the shoe, but this method causes a significant increase in cost in terms of man-hours and equipment investment. There is a cost issue. For these reasons, in the injection molding method for shoes, the sole of the shoe is formed thicker to stabilize the sole.

(5) Since the shank material itself has no elasticity and is highly hard, footwear using the shank material is generally uncomfortable to wear.

Therefore, shank materials have conventionally been used in footwear for special purposes, such as spiked baseball shoes and track and field shoes, where comfort is not a big issue.

In recent years, there has been a trend to pursue particularly light weight and durability in footwear, and to meet this objective, footwear has been provided using the so-called polyurethane direct tooling method, which uses foamable polyurethane raw materials.

However, in pursuit of lightweight and durability, these footwear have problems in terms of stability of the sole and cost, while maintaining functionality.

Therefore, in order to compensate for the functional shortcomings, there are many shoes on the market that are designed to stabilize the sole by making the sole member thicker, but this method requires a large amount of expensive materials such as polyurethane raw materials. The major drawback is that the finished product becomes expensive each time it is used.

The present invention improves the drawbacks of conventional footwear using shank materials as described above, and conducts intensive research to create footwear that is lightweight, durable, and can achieve the same effects as those using shank materials without increasing costs. As a result, it was found that a shoe sole with a shank function can be easily obtained by the known injection molding method by improving the molding die without using a shank material made of a different material as described above. This is what I discovered.

[Means for Solving the Problems] The present invention provides a shoe that integrally molds a midsole and an outsole on an upper using an injection molding machine equipped with a last covering an upper, a side mold, a dummy bottom mold, and a bottom mold. In the injection molding method, a protruding part is integrally provided on the surface of the dummy bottom mold from the tip of the flat tread part to the part where the heel is to be formed, and the midsole is made with the protruding part leaving a concave part. Next, a bottom mold is assembled below the midsole, and a second molding material is injected to fill the concave portion of the midsole with the second molding material, and at the same time, an outsole is formed.

As the + material used in the present invention, polyurethane raw materials are preferred from the viewpoint of lightweight and durability. In this case, the secondary molding material uses a higher density compound than the primary molding material. Furthermore, the use of polyvinyl chloride or the like in place of the polyurethane raw material can be arbitrarily selected depending on the intended use.

Next, the molding die used in the present invention has a structure in which a protrusion is integrally provided on the surface of the dummy bottom mold from at least the tip of the flat foot part to the heel part forming part. As shown in Figure 6, the shape of the convex part is approximately the same thickness from the heel to the middle of the non-stepping part, and is thinner and pear-shaped from the middle of the non-stepping part to the toe. The shape is such that it fits closely from the back tread to the heel. In the mold used in the present invention, the shape of the protrusions may be arbitrarily formed depending on its use and purpose, and the mold with protrusions may be newly created or an existing mold may be formed. It can be easily created by simply applying texture processing to the surface of a dummy bottom mold.

[Function] Since the present invention has the above configuration, a second molding material having a higher density than the primary molding material is placed in the recess formed on the ground contact side of the midsole made of the primary molding material. The next forming material is filled and becomes highly hard, providing shank function.

Therefore, compared to footwear with an integrally molded sole of the same thickness, the conventional urethane direct tooling method enables much better fixation of the sole, prevents foot fatigue, and improves the stability of the shoe. The loss of shape due to twisting and bending of the shoe opening is greatly improved. In addition, from a cost perspective, it is possible to make the sole thinner, which allows for a significant reduction in material costs.Furthermore, there is no need for processes such as embedding or driving shank material in the conventional method, and the sole is made thinner. The present invention has great effects, such as the fact that there is no need to worry about damage, breakage, or cracking of the bottom of the product, and that existing molds can be used by simply filling the dummy bottom mold.

[Example code] An embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the last 1 covering the upper 4 is held between the side molds B, and as shown in FIG. A dummy bottom mold C having an integrally protruding portion 7 is assembled, and the polyurethane raw material for the primary molding material is injected from the injection port 5 into the cavity X formed thereby, and the dummy bottom mold C is placed on the ground side as shown in Fig. 3. A midsole 2 with a concave portion 6 formed therein is integrally molded with a tape portion 8. Next, the dummy bottom mold C is reversed, and the bottom mold D is assembled below the midsole 2 as shown in FIG. A unique polyurethane raw material with a higher density than the molding material is injected into the injection port 5.
' to form the outsole 1 integrally with the midsole 2.

Next, a dummy bottom mold C, which is an example of a molding die used in the present invention, is formed into a pear-shaped shape as shown in FIG. It has a shape in which a protrusion 7 is integrally provided. By adopting such a shape, the protrusion 7 protruding from the dummy bottom mold C creates a groove on the ground contact side of the midsole from the stopper tread part to the heel part, as shown in FIGS. 2 and 3. The configuration is such that a concave portion 6 is formed which is filled with the secondary forming material.

[Effects] Since the present invention has the above-described configuration, the tread part is prevented from collapsing and fixed in the same way as when the shank material is buried, so foot fatigue is reduced and the twisting of the shoe itself is significantly reduced. This prevents accidental sprains and prevents the shoe opening from losing its shape due to bending.

Therefore, various problems such as foreign body feeling, high cost, and breakage caused by using conventional shank materials made of different materials can be solved at once. In addition, from a cost perspective, it is possible to fix the sole of the shoe even if the sole is made thicker, so it is possible to fix the sole of the shoe with a thicker sole. In comparison, the present invention has great effects, such as being able to reduce the cost of sole materials and being easily applied not only to special shoes but also to children's shoes to adult athletic shoes.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a state in which the molding mold of the present invention is assembled below the last covering the upper, and Fig. 2 is a sectional view showing a state in which the bottom mold is assembled below the molded midsole. Figure 3 is an explanatory sectional view showing the concave portion formed on the ground contact side of the midsole, Figure 4 is a perspective view showing an example of the appearance of the shoe of the present invention, and Figure 5 is Figure t1Y. -Y line sectional view, FIG. 6 is a diagram showing an example of the molding die (dummy bottom mold) of the present invention. A...Last B...Side mold C...Dummy bottom mold D...Bottom mold X,X
'...Gap 1...Outsole 2...Mitsudosole 3...
・Heel part 4... Instep 5.6'... Inlet 6...
Concave portion 7... Convex portion 8... Tape portion

Claims (2)

[Claims] (1) The last covering the upper is sandwiched between side molds, combined with the dummy bottom mold that forms the midsole, and the primary molding material is injected into the gap formed by this to form the midsole. The dummy bottom mold is then inverted, the bottom mold is assembled below the midsole formed in the first molding process, and the second molding material is poured into the gap formed by this. In a shoe manufacturing method using the direct sole method, which consists of a second molding process in which the outsole is formed by injection injection, in the first molding process, the molding process is performed from the tip of the ground contact area on the contact surface side of the midsole to the heel area. A shoe sole is characterized in that a concave portion is formed in the second molding step, and a second molding material having a different color or different nature and higher density than the first molding material is injected and filled into the recess in the second molding step. A method of manufacturing injection molded shoes having a shank function. (2) In an injection mold for shoes consisting of a dummy bottom mold, a bottom mold, a side mold, and a last mold that covers the upper, the dummy bottom mold extends from at least the tip of the arch to the heel forming part. ,
A mold for injection molding shoes having a shank function on the sole, characterized by integrally protruding convex portions.