JPS5835685B2 - 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 soles from forming.

Conventional shoe covers for injection molded shoes are broadly divided into those using the lasting cord method and those using the California method (bag stitching method).

Since the insole is not sewn to the last-cord type shoe cover, it is possible to freely form a gap or recess in the insole side of the shoe sole to prevent whiskers.

However, since the California style shoe cover (described later) is sewn together with the insole, it is not possible to form a gap or recess on the insole side of the shoe sole to prevent sink marks. could not get rid of the whiskers that occur during cooling.

Previously, there had been attempts to form a tunnel using the California method.

For example, there is Japanese Utility Model Publication No. 49-140239 and, as an improvement thereof, Japanese Utility Model Publication No. 55-31928, which improves the sewing operation so as not to form pleats on the outer peripheral edge of the midsole.

However, in all of these, the sole material is injected onto the inner surface of the heel part of the midsole to form a reinforcing beam. When adhering the required insole to the inner surface of the sole, it is necessary to adhere it to a plastic surface such as PVC, and there are many restrictions on the selection of adhesive, such as measures to prevent the adhesive force from decreasing due to migration and seepage of plasticizer. Since it is a hydrophobic substance, it is necessary to use a solvent-based adhesive, and water-based adhesives have the disadvantage that they cannot be used because their polarities do not match.

The purpose of the present invention is to eliminate the above-mentioned drawbacks, by forming one or more notches in the middle sole of a jacket sewn using the California method, and forming a groove corresponding to the notches in the bottom surface of the last. The shoe cover is attached to the last with protrusions, and the sole material is injected into the space formed by the side mold and the bottom mold, so that the sole is integrally molded with the shoe cover and a recessed area for preventing sink marks is formed. A manufacturing method for injection molded shoes that prevents sink marks on the soles, which is characterized by forming a sole, which prevents whiskers, shortens cooling time, saves on sole materials, makes the soles lighter, allows the use of water-based adhesives, etc. It exhibits extremely excellent effects.

The present invention will be explained below with reference to Examples.

As shown in FIGS. 1 and 2, the midsole 9 has one or more notches 8 provided in the heel portion in the vertical direction.
The outer circumferential edge of the upper 11 and the lower circumferential edge of the upper 11 are sewn together using a normal bag stitch, that is, the California method, to form a jacket 1.

The last 2 on which the yoke 1 is attached has a protrusion 7 on the heel part on the ground side.
protrudes, and the protrusion 7 is formed into a substantially rectangular parallelepiped shape,
It is configured to correspond to the notch 8 of the midsole 9.

The space 5 corresponds to the sole 6 of the shoe, and is composed of a last 2 to which the shoe cover 1 is attached, a side mold 3 button, and a sole mold 4.

The sole material is injected into the space 5 from the injection hole 12, and the sole 6 is formed.
is integrally molded on the cover 1.

The shape of the protrusion 7 can be appropriately selected such as semi-elliptical or triangular in cross section, and the protrusion 7 forms the recess 10 for preventing sink marks.

When attaching the lace cover 1 to the last 2, first cover it from the toe portion of the lace cover 1 to the toe portion of the last 2, and then attach it to the heel portion of the last 2 while pulling the heel portion of the lace cover 1. Therefore, the insole 9 will be pulled in the vertical direction, so
Although it is preferable to form the cut portions 8 of the midsole 9 in the vertical direction, they may be formed in any appropriate direction such as the horizontal direction or the diagonal direction.

The notches 8 and the protrusions 7 are not limited to the heel portions of the heel 1 and the last 2, respectively, and can be formed at any location where sink marks occur.

The notch 8 may simply be a cut, but it may be a notch smaller than the width of the base of the protrusion 7, or a cut that is narrower in width than the base of the protrusion 7 but slightly longer in length. If there is a chip, the desired effect can be achieved.

At this time, it is necessary to take care that the cut does not reach the seam allowance for sewing the midsole 6 to the upper 11.

This is because if the seam allowance of the midsole 9 is not completely maintained, the relative positional relationship between the midsole 9 and the upper 11 may be misaligned when the midsole 9 is sewn to the upper 11, and the notch 8 may be This is because the width becomes wider, making it difficult to align the notch 8 of the midsole 9 with the protrusion 7 of the last 2, causing a large amount of sole material to leak into the inner surface of the midsole.

Although it is more efficient to form the cut portion 8 at the same time as cutting the inner sole 9, it may be formed after the cut portion 8 is sewn together with the upper 11.

In this case, there is no problem of securing the seam allowance mentioned above, and the position of the cut becomes more accurate.

After attaching the cover 1 to the last 2, cut out the notch 8 in the inner sole 9.
Press the sides to make the protrusion 7 protrude from the notch 8.

In practice, even if the last protrusion is not completely penetrated and exposed from the notch in advance, the last protrusion 7
If the structure is such that the notch part 8 of the inner sole 9 of the cover 1 matches, the floor material itself flowing when the bottom material is injected presses the inner sole 9 around the notch, thereby forming the protrusion. 7 is passed through the notch 8.

That is, as shown in FIG.
The notch 8 formed at the heel of the midsole 9 bridges the protrusion 7 of the last 2, and is composed of the last 2 to which the sleeve 1 is attached, the side mold 3, and the bottom mold 4. The bottom material is injected into the space 5 through the injection hole 12.

As the bottom material is injected into the space 5, the injection pressure causes the inner sole 9 to be pushed out from the protrusion 7 of the last 2 by the notch 8, and to reach the positional dimension shown by the dotted line along the outer peripheral surface of the protrusion 7. As a result, as shown in FIG. 2, a desired sinking prevention recess 10 is formed on the inner surface of the inner sole 9 with almost no leakage of the sole material.

After filling the space 5 with the sole material and cooling it for a certain period of time, the bottom mold 4 and side mold 3 are retreated and removed from the last 2, and then the insole 14 is adhered to the inner surface of the midsole 9 to obtain a product.

Sponge rubber is generally used for the insole 14.

As the adhesive for the insole 14, since the inner surface of the insole 9 is made of cloth in the present invention, either a solvent-based adhesive or a water-based adhesive can be used.

In water-based systems, general latex adhesives made of natural rubber, synthetic rubber, synthetic resin, etc. adhere well to the inner surface of the midsole 9, and since there is cloth, even in the case of PVC soles, the adhesive may soften due to migration and seepage of plasticizer. No deterioration.

In the case of sponge rubber insoles, even though the material is hydrophobic, the latex adhesive permeates into the pores and provides sufficient adhesive strength due to the anchoring effect, but in the case of solid rubber or plastic insoles, the insole Water-based adhesives can be used by applying nonwoven fabric or cloth to the adhesive surface.

As described above, the present invention provides a shoe cover 1 in which a notch 8 that does not reach the seam allowance is provided in the midsole 9 corresponding to the region of the shoe sole 6 where whiskers are formed.
is attached to the last 2 which is provided with a protrusion 7 having a width larger than the width of the notch 8 at a portion corresponding to the notch 8, and the protrusion 7 passes through the notch 8 of the inner sole before or during injection. The recessed part 10 is formed as a clearance on the midsole surface, and the sole 6
In this method of manufacturing injection molded shoes, the volume of the thick part of the sole 6 is reduced by the recessed part 10 formed on the 9 surfaces of the midsole, thereby shortening the cooling time and reducing the shrinkage. is prevented.

In the past, the protrusion 7 on the last 2 was wider than the width of the notch 8 on the inner sole 9.
By forming the width of the insole to be large, when the protrusion 7 passes through the notch 8, the edge 13 of the notch 8 remains along the side surface of the protrusion γ. (Inner surface) The bottom material of the borrowed scenery may leak from the slightly longer cut part of the notch 8, but it did not leak in the past.
There is almost no leakage of the sole material on the inner surface of the midsole, and the cloth surface can be maintained.

Since the inner surface of the insole 9 is made of cloth, there is a wide selection of adhesives for the insole 14, especially water-based adhesives, which have great advantages in terms of workability, disaster prevention, and hygiene, and also contain plasticizers. P
Even in the case of a bottom material containing a migratory substance such as a VC sole, the cloth prevents migration and prevents softening and deterioration of the adhesive.

[Brief explanation of the drawing]

Fig. 1 is a plan view of a cover showing an embodiment of the present invention, Fig. 2 is a partially cutaway perspective view showing the main parts, and Fig. 3 is a partially cutaway cross-sectional view showing an embodiment. It is a front view. 1... Shoe cover, 2... Last, 3... Side mold, 4... Bottom mold, 5... Space, 6...
・Sole, 7...Protrusion, 8...Notch, 9...Insole, 10...Concave groove 11...Upper, 12...
Injection hole, 13... Edge, 14... Insole.

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.
For the manufacturing method of injection molded shoes, in which the sole material is injected, the sole 6 is integrally molded on the shoe cover 1, and the insole 14 is bonded to the inner sole 9 surface after demolding, the beard of the sole 6 is removed. A patch cover 1 is provided with a notch 8 that does not reach the seam allowance in the midsole 9 corresponding to the area where the seam is formed, and a protrusion 7 having a width larger than the width of the notch 8 is provided in a part corresponding to the notch 8. Attach to last 2, middle sole 9
The method for manufacturing injection molded shoes as described above, characterized in that a concave portion 10 is formed on the surface of the midsole 9 by the indentation 7 passing through the notch 8 of the shoe, thereby preventing whiskers.