JPS5855763B2 - How to make injection molded shoes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing injection molded shoes that prevents sink soles.

Injection-molded shoes tend to have sink marks in the thick part of the sole, so a recessed part called a so-called "sink" is provided to reduce the volume of the sole to reduce the wall thickness and prevent sink marks from occurring.

In the manufacturing method of injection molded shoes, there is a method in which the sole material is integrally injection molded using a cord-lasting method in which an upper without a midsole is attached to the last and the lower edge of the upper is tightened with a cord, and There are two main methods: using the California method, which involves attaching a bag-stitched cover to the last, and then integrally injection molding the bottom material.

Since the former shoe does not have an insole, it is easy to prevent sink marks by forming a concave part in the insole of the shoe by forming appropriate protrusions on the bottom of the last.

The latter case is not as easy as the former because of the insole.

Previously, there had been attempts to form a tunnel using a California-style cover.

For example, there is Japanese Utility Model Publication No. 49-140239 and, as an improvement thereof, Japanese Utility Model Publication No. 55-31928, in which the sewing operation is improved so that the outer peripheral edge of the insole is not pleated.

However, in all of these, the sole material is injected onto the inner surface of the heel of the midsole to form a reinforcing beam, and when the sole material is a plastic such as soft vinyl chloride (hereinafter referred to as PVC) When adhering the required insole to the inner surface of the bottom, it is necessary to adhere it to the PVC or plastic surface, which imposes great restrictions on the selection of adhesive, such as measures to reduce adhesive strength due to the infiltration and migration of plasticizer. Since plastics are hydrophobic substances, it is necessary to use solvent-based adhesives, and water-based adhesives have the disadvantage that they cannot be used because their polarities do not match.

The present invention eliminates the above-mentioned drawbacks and provides a manufacturing method for preventing sink marks in injection molded shoes by forming a concave part on the midsole surface while leaving the cloth on the inside surface of the midsole using a California method. It is.

This will be explained below using examples.

In the present invention, in order to provide a gap in the area of the sole 6 where sink marks occur, a protrusion 9 is provided at a corresponding portion of the bottom surface of the last 2, as shown in FIG. For example, a knife-shaped last 2 is used.

The protrusion 9 is generally rectangular in shape and is generally provided in the vertical direction of the shoe, but it is provided as appropriate to achieve the purpose of slippage and to provide strength when worn.

Attach the cover 1 made of the upper 13 and the midsole 7 to the last 2, and press the protrusion 9 from above the midsole 7 with a rubber plate or the like while moving it back and forth in the front and back direction of the shoe. 7 has a notch 11 made by the tip 10 of the protrusion 9.

At this time, it is also effective to press the midsole 7 with a jig having a concave portion that roughly resembles the cross section of the protrusion 9.

Once the notch 11 is made in the midsole 7, the edge 14 of the notch 11 is pressed down to allow the protrusion 9 of the last 2 to pass through the notch 11 and appear.

After that, the bottom material is injected from the injection hole 15 into the space 5 formed by assembling the last 2 with the cover 1 attached, the side mold 3, and the bottom mold 4 in a conventional manner, and after cooling, the mold is removed. As shown in FIGS. 2 and 3, an injection molded shoe is obtained in which a concave portion 12 is formed as a clearance on the 7th surface of the midsole.

A cut 1 is made in the inner sole 7 by the tip 10 of the protrusion 9 of the last 2.
1 is formed, it is not necessary to press the edge 14 of the notch 11 as described above and make the protrusion 9 of the last 2 penetrate through the notch 11 as shown by the dotted line in FIG. If injection molding is performed with the notch 11 still formed in the bottom 7 or with the tip 10 of the protrusion 9 of the last 2 slightly exposed from the notch 11, the injected bottom material will press the edge 14 of the notch 11 due to the injection pressure. The last 2 is pressed down, so that the protrusion 9 of the last 2 emerges from the notch 11, and the desired recess 12 is formed on the inner sole 7.

Insole 7 is made by layering a thermoplastic material with good adhesion to the bottom material (for example, using PVC in the case of a PVC sole) on one side of a thin cloth, and upper 1 is made with the cloth side inside.
If you use the cover 1 that is double-stitched on 3, even if you attach it to the last 2, assemble it into a mold without any process, and then inject the bottom material, the heat of the injected bottom material will reduce the heat of the inner sole 7. The plastic material softens and the strength of the midsole 7 during heating is reduced, and the injection pressure of the sole material presses the thin fabric of the midsole 7 against the protrusion 9 of the last 2, and the protrusion 9 is pressed against the protrusion 9 of the last 2 by its tip 10. 7, pass through this notch 11, and form the desired concave portion 1.
2 can be formed on the seven sides of the inner sole.

A solvent-based or water-based adhesive is applied to the inner surface of the insole 7 of the shoe that has been removed from the mold after injection molding, and the insole 8 is adhered to obtain a product.

The present invention provides a last 2 that corresponds to the region of the sole 6 where whiskers occur.
A protrusion 9 of an appropriately shaped shape is provided on the bottom surface of the protrusion 9, and the tip 10 of the protrusion 9 is made into a sharp shape. Since the notch 11 is made in the midsole 7 by , the position where the protrusion 9 should penetrate and the notch 11 in the midsole 7 completely match, and the protrusion 9 having a certain width penetrates the notch 11 which has almost no width. At this time, the edge 14 of the notch 11 remains along the side surface of the protrusion 9, which prevents the sole material from leaking onto the inner surface of the inner sole 7. An injection molded shoe is obtained having a concave portion 12 of
This can prevent beards.

In the present invention, since the inner surface of the insole 7 is made of cloth, a water-based adhesive can be used for adhering the insole 8, which has the excellent effect of preventing whiskers while maintaining workability, disaster prevention, and hygiene benefits. It is something that demonstrates the.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway sectional view showing an embodiment of the present invention;
Fig. 2 is a partially cutaway perspective view showing the main parts of one embodiment, and Fig. 3 is a plan view of an injection molded shoe.・Last, 3...
...Side mold, 4...Bottom mold, 5
・・・・・・Space part, 6... Sole, 7...
... Insole, 8 ... Insole, 9 ... Protrusion,
10... Tip, 11... Cut, 12
・・・・・・Recessed portion, 13... Upper 14・
... Edge, 15 ... Injection hole.

Claims (1)

[Claims] 1. A space 5 formed by the last 2 to which the bag-stitched shoe cover 1 is attached, the side mold 3, and the bottom mold 4.
Then, the sole material is injected and the sole 6 is integrally molded on the shoe cover 1.
In a method for manufacturing injection molded shoes in which an insole 8 is bonded to the inner sole 7 surface after demolding, a protrusion 9 of an appropriately shaped shape is provided on the bottom surface of the last 2 corresponding to the area of the sole 6 where sink marks occur. Attach the cover 1 to the last 2 whose tip 10 has a sharp shape,
The injection molding described above is characterized in that a notch 11 is made in the midsole 7 by the tip 10 of the protrusion 9, and a concave portion 12 is formed on the surface of the midsole 7 by the protrusion 9 passing through the notch 11 to prevent sink marks. How to make shoes.