JP2010042547A - Method for producing safety shoes - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing safety shoes which can prevent the occurrence of defective product in demolding by a simple structure at a low cost. <P>SOLUTION: Since projections 3 of a pair are fixed on the inner blade bone side and outer blade bone side of the front part of a last mold 7, the occurrence of a burr by the projections 3 is prevented during injection molding. Since an inclination part which inclines diagonally inward in the rear to the longitudinal direction of the shoes is provided at the tip 31 of the projection 3, during demolding, the engagement part 5 of a point core 2 is rotated smoothly around the projection 3, and the point core 2 can easily be separated from the last mold 7. The projection 3 can be prevented from breaking through a safety shoe 1 body during demolding. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a safety shoe manufacturing method for manufacturing a safety shoe having a resin tip inside a toe portion by injection molding.

  Conventionally, safety shoes with a cap-shaped steel tip to protect the toes even if heavy objects fall on the feet are known. In the case of manufacturing by injection molding in which a resin material is injected into the gap of the tip, the tip is positioned by the action of magnetic force, for example, using a magnet and a spacer in the part where the tip of the last mold (inner mold) is mounted. It has been known.

On the other hand, when the tip is made of resin, the above method cannot be applied. In this case, for example, a retractable collar (projection) is compressed in the hole formed in the toe portion of the last mold. While energizing outward by a spring, a through hole is provided in the tip, and after positioning the tip by inserting a projection through the through hole, a resin material is formed in the gap formed using this last mold. (For example, Patent Document 1).
JP-A-2-109502

  However, in patent document 1, since the projection part urged | biased with a compression spring is provided in a last mold, an installation becomes complicated and cost reduction becomes difficult. In addition, since there is a gap between the movable protrusion and the hole, the resin material enters the gap by injection pressure during injection molding, and thus burrs are generated, causing shoe rubbing and the like, resulting in a defective product. There is a case. Furthermore, there has been a problem in that when the mold is removed, the tip can not be smoothly removed from the last mold, and the protrusion may break through the safety shoe body.

  An object of the present invention is to solve the above-mentioned problems and to provide a method for manufacturing safety shoes that can prevent the occurrence of defective products at the time of demolding with a simple structure and low cost.

  In order to achieve the above object, a method of manufacturing a safety shoe according to one configuration of the present invention includes injecting a safety shoe having a cap-shaped tip core made of resin in a toe portion and an injection molding material into a gap between molds. A pair of protrusions protruding outward are fixed to the inner flange side and the outer flange side of the front part of the last mold, respectively, and the tip is located at a position opposite to the pair of protrusion parts. And a pair of engaging portions that are engaged with each of the protruding portions, and at the tip of each protruding portion, an inclined portion that is inclined obliquely inward and backward with respect to the longitudinal direction of the shoe in plan view is formed. A safety shoe is manufactured by injection molding in a state where the tip is held in the toe portion by the projections engaged with the engagement portions.

  According to this configuration, since the pair of protrusions are fixed to the inner flange side and the outer flange side of the front part of the last mold, the occurrence of burrs due to the protrusions during injection molding is prevented, and at the tip of the protrusions Since it has an inclined part that inclines backward and inward with respect to the longitudinal direction of the shoe, it is easy to remove the tip from the last mold by smoothly rotating the tip engaging part around the protrusion when removing the mold. It is possible to prevent the projections from breaking through the safety shoe body at the time of demolding. Thereby, generation | occurrence | production of the inferior goods in the case of mold release can be prevented with simple structure and low cost.

  Preferably, the inclination angle at the inclined portion at the tip of each projection is in the range of 30 to 70 degrees with respect to the longitudinal direction of the shoe. Therefore, the tip can be detached from the last mold more smoothly during demolding.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing a safety shoe according to the present invention, and FIGS. 2A and 2B are longitudinal sectional views showing a method for manufacturing a safety shoe according to an embodiment of the present invention.

  As shown in FIG. 1, this safety shoe 1 has a cap-shaped tip 2 made of resin in the toe portion 1a. As shown in FIG. The injection molding material (thermoplastic resin) 15 is injected into the gap 10 between the side mold 8 and the bottom mold 9 and is manufactured by injection molding. For example, a material in which a reinforcing fiber such as glass fiber or carbon fiber is impregnated with polyamide, polycarbonate, or the like is used as the resin constituting the core 2. For example, polyvinyl chloride (PVC) is used as the thermoplastic resin 15 of the injection molding material.

  As shown in FIG. 3, a pair of projecting portions projecting outward on the inner heel side and the outer heel side of the front part (upper part in the drawing) of the last mold 7 substantially symmetrically with respect to the center line O of the shoe width. 3 and 3 are fixed. At the tips 31, 31 of the projections 3, 3, the inclined portions are inclined rearward (downward in the drawing) obliquely inward with respect to the longitudinal direction of the shoe (a direction perpendicular to the width direction of the shoe) X in a plan view. 32 is formed. The protrusions 3 and 3 are processed by overlaying (welding, cutting), digging, or the like.

  The inclination angle α of the inclined portions 32 and 32 of the tips 31 and 31 of the protrusions 3 and 3 is in the range of 30 to 70 degrees with respect to the longitudinal direction X of the shoe in plan view. More preferably, the inclination angle α is in the range of 40 degrees to 60 degrees.

  In this example, the inclined portion 32 is formed at a part of the tip 31, but the entire tip 31 may be inclined. Further, although the inclined portion 32 is formed in a flat shape, it may be formed in a curved shape such as a convex curved shape instead.

  As shown in FIG. 4, the lead core 2 includes a pair of engaging portions 5 and 5 that are engaged with the protruding portions 3 and 3, respectively, at positions opposed to the pair of protruding portions 3 and 3. Each of the engaging portions 5 and 5 includes, for example, a round hole 5a in a side view and a long hole 5b having a slightly wider taper communicating with the round hole 5a. The lead core 2 can be smoothly detached from the protrusions 3 and 3 of the last mold 7 by the tapered long holes 5b and 5b. FIG. 5 shows an engaged state between the protruding portion 3 of the last mold 7 and the engaging portion 5 of the tip 2.

  The safety shoe 1 is manufactured by injection molding in a state where the tip 2 of FIG. 2A is held in the toe portion 1a by the projections 3 of the last mold 7 engaged with the respective engagement portions 5. Is done.

Hereinafter, a method for manufacturing the safety shoe 1 according to the present invention will be described.
First, in FIG. 2 (A), the pair of protrusions 3 and 3 of the last mold 7 are respectively paired with the tip 2 so that the tip 2 is disposed slightly above the last mold 7 in the toe portion 1a. Are engaged with the engaging portions 5 and 5 (FIG. 5). In this way, the tip 2 is securely held in a state of being floated in the toe portion 1a of the last mold 7. In this case, since the pair of protrusions 3 and 3 are fixed to the last mold 7, the occurrence of burrs during injection molding due to a gap between the movable protrusion and the hole as in the conventional case is prevented. can do.

  Thereafter, the gap 10 is formed by adding the side mold 8 and the bottom mold 9 to form a mold. The gap portion 10 is injected and filled with a thermoplastic resin 15 as an injection molding material from the injection hole 12 of the bottom mold 9 and then demolded.

  When removing the mold, first, the side mold 8 and the bottom mold 9 are removed, and then the safety shoe 1 body is removed from the last mold 7 while rotating in the R direction as shown in FIG. In this case, as shown in FIG. 5, the tip 31 of the projection 3 of the last mold 7 has an inclined portion 32 that is inclined obliquely backward and inward (in the drawing, obliquely downward) with respect to the longitudinal direction X of the shoe. At the time of molding, the tip 2 can be smoothly rotated in the R direction around the projection 3 by the inclined portion 32 of the projection 3 using the round hole 5a (FIG. 4) of the engagement portion 5. In addition, the tip 2 can be easily detached from the protrusion 3 of the last mold 7 by the tapered long hole 5b (FIG. 4). For this reason, it is possible to prevent the protrusion 3 of the last mold 7 from breaking through the main body (resin) 15 of the safety shoe 1.

  Thus, since the pair of protrusions 3 and 3 are fixed to the inner flange side and the outer flange side of the front part of the last mold 7, it is possible to prevent the protrusions 3 and 3 from generating burrs during the injection molding and 3 has an inclined portion 32 inclined obliquely inward and backward with respect to the longitudinal direction X of the shoe, so that when the mold is removed, the engaging portions 5 and 5 of the tip 2 are smoothly inserted into the protruding portion 3. The tip 2 can be easily detached from the last mold 7 by rotating around three, and it is possible to prevent the protrusions 3 and 3 from breaking through the main body (resin) 15 of the safety shoe 1 during demolding. it can. Thereby, generation | occurrence | production of the inferior goods in the case of mold release can be prevented with simple structure and low cost.

  In addition to the protrusions 3 and 3, the last mold 7 forms an overlay on the top of the tip of the tip 2 and the bottom of the toe to prevent unnecessary rotation of the tip 2 at the time of resin injection. You may make it prevent.

It is a longitudinal section showing safety shoes concerning the present invention. (A), (B) is a longitudinal cross-sectional view explaining the manufacturing method of the safety shoes which concern on one Embodiment of this invention. It is a top view which shows the last mold with the projection part used with the manufacturing method of FIG. It is a perspective view which shows the tip used in the manufacturing method of FIG. It is a cross-sectional view showing the engagement state between the projection part of the last mold and the engagement part of the tip.

Explanation of symbols

1: Safety shoe 2: Tip core 3: Protruding part 5: Engaging part 7: Last mold 8: Side mold 9: Bottom mold 10: Gap part 15: Injection molding material (resin)
31: Tip of protrusion 32: Inclined portion of tip X: Longitudinal direction of shoe α: Inclination angle

Claims (2)

A safety shoe manufacturing method in which a safety shoe made of resin and having a cap-shaped tip in the toe portion is manufactured by injecting an injection molding material into a gap between molds,
A pair of protrusions protruding outward are fixed to the inner flange side and the outer flange side of the front part of the last mold,
The tip is provided with a pair of engaging portions that engage with each of the protruding portions at positions opposite to the pair of protruding portions,
At the tip of each projection, an inclined portion is formed that is inclined obliquely inward and backward with respect to the longitudinal direction of the shoe in plan view,
A safety shoe manufacturing method in which a safety shoe is manufactured by injection molding in a state where the tip is held in the toe portion by the projections engaged with the engagement portions. In claim 1,
The method for manufacturing safety shoes, wherein an inclination angle at an inclined portion at a tip of each protrusion is in a range of 30 degrees to 70 degrees with respect to a longitudinal direction of the shoes.

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