JPH0481445B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to footwear, and in particular, it is used in shoes, boots, overshoes, and other footwear to structurally reinforce the toe of the toe, and to protect the toe from falling or hitting the toe. This invention relates to a toe cap that prevents the wearer from being injured by objects.

<Conventional technology> Internal toe caps are attached to shoes for structural reinforcement.
It has been known for a long time to provide footwear such as boots, and it is commercially available. This type of footwear is worn by industrial workers, firefighters, loggers, military personnel, and others who work in environments where the risk of foot injury from heavy objects is relatively high. Conventionally, toe caps are made of metal, particularly steel, to provide maximum strength for a limited wall thickness.

There are some restrictions on the design of the toe cap, which requires a shell-like structure. 1st
In order to enclose the toe of the wearer within the protective pocket, the protective pocket should be of approximately the same volume and shape as the toe of a normal shoe for conformity and comfort. Additionally, it must be lightweight for practicality and comfort, and it must conform to the shape of the toe of the shoe for practicality and aesthetics.

In recent years, plastic toe caps have become commercially available to replace the traditional steel ones. Plastic ones have several advantages. That is, it is lightweight and causes less fatigue to the user even when worn for long periods of time. Plastic has a low thermal conductivity, making it comfortable in cold weather and reducing the risk of frostbite.

<Problems to be Solved by the Invention> Since plastic is not ductile, if it is subjected to stress exceeding its limit, it will flex to some extent and then break. As soon as the load acting on the safety shoe is removed, the wearer is immediately relieved of stress.

Metals, on the other hand, may undergo some damage or permanent deformation without failure when subjected to stress exceeding their yield point. In the case of safety shoes, this permanent deformation does not recover even if the load or object that caused the deformation is removed. Therefore, it may be difficult to remove the shoes, and pain or suffering may continue.

The plastic toe cap is non-magnetic and
It can be electrically conductive or non-conductive as desired. Plastic toe caps will not corrode and
Not affected by moisture or sweat.

The first problem with replacing steel toe caps with plastics is that they have lower compressive and tensile strengths than steel, making them less suitable for structural reinforcement. The United States and other countries have standards for toe cap testing and standards. In the United States, compression and impact tests are described in Z41-1983 as an ANSI standard. In Europe, impact testing is described in DIN standard 4843. Conventional plastic toe caps do not meet these standards.

The object of the present invention is to provide a plastic toe cap that overcomes this problem.

<Means for Solving the Problems> The toe cap according to the invention is a toe cap attached to a shoe to provide structural reinforcement of the toe area against compressive and impact loads, the toe cap having the shape of the toe of the shoe. a shell body made of plastic material forming a pocket portion, the shell body having a rearwardly facing opening at the entrance of the pocket portion for insertion and removal of a toe;
It has a front wall portion, left and right horizontal wall portions, and a roof portion, and the roof portion extends in the horizontal direction from approximately the highest point in the longitudinally extending central plane of the shell body to the left and right horizontal wall portions. and extends forward to the front wall portion, the side wall portion and the front wall portion being joined to each other and continuous to the roof portion with a smooth curve, the front wall portion and the side wall portion being a roof portion extending upwardly from a generally planar base shaped to conform to the front portion of the sole, said roof portion transferring compressive and impact loads applied to said roof portion laterally outwardly to said lateral wall portion; The present invention is characterized in that the structure is such that the rupture stress due to the load is generated not in the roof portion but in the side wall portion.

This feature can take several different embodiments.

In a first form, this arrangement is provided by providing the inner or outer surface of the roof section with a series of grooves extending substantially parallel to the central plane.

As a second form, the above-mentioned configuration is such that the wall thickness of the roof portion gradually decreases from the region adjacent to the side wall portion toward the region of the central plane, and becomes the minimum in the region of the central plane. It is given according to what you have done.

In a third embodiment, the above arrangement is provided by forming the roof section from a plastics material having a greater flexibility than the plastics material forming the side wall sections.

<Function> According to the toe cap according to the present invention, in any of the above embodiments, the roof portion has greater flexibility than the side wall portion. Therefore, when compressive and impact loads are applied to the roof portion, the roof portion easily deforms and becomes flat, and the load is mainly supported by the left and right side wall portions. That is, the loads applied to the roof portion will be transferred laterally outwardly from the roof portion to the side wall portions. As a result, the breaking stress due to this load occurs not in the roof part but in the side wall part. The upwardly extending left and right side wall portions are suitable for supporting large loads. Therefore, in the conventional toe cap, even when a not very large load was applied to the roof part, the toe cap would break near the central plane area of the roof part, but in the toe cap of the present invention, the toe cap would break even when the roof part was subjected to a not very large load. The side wall section only breaks when it is subjected to a fairly large load.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a safety shoe, generally indicated by the numeral 10, which includes an inner toe cap 12 according to the invention. The cap 12 is attached to the toe area and provides structural reinforcement of the shoe against compressive or impact loads due to objects falling or moving into the toe area. Toe cap 12 may be attached to another type of footwear, such as a boot, or may be placed over a shoe for safety and protection. The term "shoe" is used herein in a broad sense.

The safety shoe 10 is of a conventional type and includes a front part 14 and a heel part 16 of leather, rubber, or synthetic resin, an outer sole 18 of hard rubber, leather, etc., a cushioned insole 20, and an inner lining, for example. Including other comfort features such as color. Additionally, a reinforced heel, a protective shank in the sole, and other additional features may be provided as desired. A cap 12 is provided on the bottom 18 and within the shape of the top 14.

2-5 show details of the toe cap 12 according to the present invention. It consists essentially of a shell body made of plastic material. The term "plastic" is used in a broad sense and includes synthetic resin materials, both thermoplastic and thermoset, with or without reinforcing fibers. Suitable thermoplastic synthetic resins include polyvinyl chloride (PVC), ABS (polymerized mixture of styrene, acrylonitrile, and nitrile rubber), polycarbonate, polyethylene, polyethylene terephthalate, polypropylene, polyurethane, polyphenylene sulfide, polyether ether ketone, There are polyetherimides, polyamideimides and mixtures thereof. Suitable thermosetting resins include phenolic resins, polyesters, epoxies, polyamides, polyacrytamates, and the like, along with selected reinforcing fibers and fillers.

The plastic materials mentioned above may be reinforced with glass fibers, carbon, graphite, Kevlar fibers, etc.

Generally, toe cap 12 according to the present invention can be molded. Compression molding, injection molding, resin conversion methods, injection compression molding, pressure molding, etc. are suitable for the various resins mentioned above. Injection molding is undesirable when using reinforcing fibers due to the reduced quality of the fiber length and limitations on its orientation.

One embodiment according to the present invention was made from glass fiber reinforced polyphenylene sulfide (PPS).
The glass fiber reinforced PPS was first preheated in a furnace to preform to the appropriate weight, and then heated and pressed into the final shape in a cold compression mold. The reinforcing fiber was 40% of the weight of the final product, and swirl mat fiber was used.

In another example according to the invention, a glass fiber reinforced polyurethane resin was preheated in an extruder. The appropriate amount of material is placed in a compression mold and molded to the final shape under pressure. Initially, the length of glass fiber is 1/2-2
inch (13-50mm), after passing through the extruder 1/
It became 4-1 inch (6-25 mm). The volume ratio of resin and glass fiber was approximately 60%. A high volume ratio may be provided, for example 100% (without glass fibers).

The ones shown in FIGS. 2 to 5 are of integral construction as a hollow shell body approximately shaped like the toe of a shoe. The shell body has a rearwardly facing opening 26 for providing toe access and for creating a pocket portion when attached to a shoe.

The shell body has a roof portion 30 at the top, a front wall portion 32 at the front, a right side wall portion 34 on the right side, and a left side wall portion 36 on the left side. Both side wall parts 34, 36
are approximately equidistant from the longitudinal midplane 38, and FIG. 5 is a cross-section along the midplane. The divisions of the roof and each wall section are shown in dashed lines in FIG. 3, but the exact division of each section is not important. These parts form smooth continuous curves and are joined together to have an aesthetically pleasing external shape that fits the toe of the shoe, and an internal shape for constructing the shoe.

The wall portions 32, 34, and 36 project vertically upward from a substantially planar base, as shown in FIGS. 4 and 5, and are shaped to match the front portion of the sole. The lower end of each wall section is bent inward to form a wide seating surface for supporting the toe cap 12 on the sole. Cap 12 may be attached to the sole of the shoe by adhesive or other suitable means, and may be positioned and secured by surrounding material (if cap 12 is attached to the inside of the shoe). A recess may be provided in the sole to receive the lower edge of the wall portion and may be sewn together with the facing 14 and lining material to retain the cap 12.

The roof section 30 extends generally horizontally in a generally arcuate manner in the longitudinal and transverse planes. As shown in Figures 4 and 5, the highest point of the arcuate line is located somewhat forward of the trailing edge of the toe cap and in the midplane. This highest point is the point at which a falling or moving object on the toe cap first contacts the toe cap.

The toe cap of FIGS. 2-5 does not have a floor portion; the sole 18 closes off the bottom of the toe cap 12. However, the cap 12 may also be provided with an integral floor section, which eliminates the need for the sole 18 to be of high strength and prevents the risk of foreign objects penetrating the sole and causing injury to the user. be able to.

The roof portion of the toe cap 12 according to the invention is provided with means for moving load stresses outwardly away from the central plane 38. In the illustrated embodiment, a series of grooves 40, 42, 44, 46, 4
8, 50 from the rear edge 52 of the roof portion to the cap 12
It extends vertically to a position midway between the front end and the rear end. The number, length and depth of grooves may vary depending on the design. When the width of the toe cap is wide, the stress is distributed over a wide range, and when the length in the longitudinal direction is long, the length of the groove is lengthened to achieve the desired stress transfer (described later). The groove may be provided only on either the inner or outer surface of the shell body, but when the height is high, it is desirable to provide it on both sides.

As shown in FIG. 4, the grooves extend partially from the inner or outer surface to increase the flexibility of the roof section when loads are applied vertically to the top of the toe cap. Flexibility has the effect of transferring the resistance or stress that occurs against the load from the roof section to the wall section, which allows the load to be supported without excessive deformation or damage. becomes.

FIG. 6 shows the deformation that occurs in the toe cap 12 according to the invention when a load L is applied to the roof section 30. The state when no load is applied is shown by the chain line. As shown by the solid line, large deformation and flattening occur in the roof area. This spreads the load laterally towards the wall sections 34, 36 and onto the roof section 30. As a result, a load L is applied to the center of the bow-shaped roof section.
without any critical stresses acting on it, causing it to move outwardly from the center towards the wall sections 34, 36. Note that stress transfer also occurs toward the front wall portion 32 as well.

Numerous tests of toe caps 12 have shown that, in those without a flexible roof section, rupture typically occurs at the trailing edge of the midplane 38. In the toe cap according to the invention with a flexible roof part, the roof part flexes without breaking, and the breakage occurs in the side wall parts as shown by arrows a and b.

It should be noted that the toe cap 12 according to the invention with its flexible roof portion ruptures at significantly higher loads than conventional plastic ones. Since the roof section is flexible, it will not support the load, so the load will be transferred outward and carried by the wall section. The wall portion projects vertically upwards from the sole and is therefore suitable for supporting loads without fracture. That is, given the size and weight, a toe cap with a flexible roof portion can support large loads.

FIG. 10 shows compression and impact test results for toe caps made of plastic material. Sample A has substantially the same shape and dimensions as those previously described and illustrated, but is made of a fiber-reinforced plastic material of uniform wall thickness throughout. Compression and impact tests were conducted according to ANSI standards. Compression test failure is determined by a 1/2 inch gauge (steel rod) opening 26 at the trailing edge of the cap.
Judgment was made by no longer entering the room.

The results of the compression test for sample A are shown as rectangle 60. The top and bottom edges of the rectangle indicate the highest and lowest breaking loads for multiple samples, and the dashed line and number in the middle indicate the average breaking load. The dashed line 68 indicates the standard or required value according to this standard.

Points 70, 72, 74, and 76 in FIG. 10 indicate the impact test results. The numbers on the vertical axis indicate the height of the pocket portion after the test as a fraction of an inch, and the broken line 78 indicates the passing standard value.

Sample B is structurally almost the same as sample A, but has improved fiber length and distribution,
Although there is some improvement over Sample A as shown by rectangle 62 and point 72, it falls short of standards in both the compression and impact tests.

Sample C has grooves in the roof portion as shown in FIGS. 2 to 5. The test result is 64,
It satisfies the ANSI standard as shown in 74. Sample C
The compression test results are desirable because they have high reproducibility, as is clear from the fact that the upper and lower limits of the rectangle 64 are close to each other.

7 and 8 illustrate a toe cap 80 as another embodiment of the present invention. This is from Figures 1 to 5.
It is made of a plastic material similar to the toe cap 12 shown. The roof section 82 is made as a distinct piece from the wall section 84. That is, cap 80
is not a single shell body, but consists of two different pieces.

Roof portion 82 and wall portion 84 may be mechanically connected, such as by a snap fit, or may be joined by a resin adhesive (such as epoxy resin) that is compatible with both portions.

Toe cap 80 functions similarly to toe cap 12. The roof portion 82 has sufficient flexibility,
Loads acting on the top of the arc are moved outwardly from the central plane toward wall portion 84. This flexibility is achieved by having the roof portion 82 have a thin wall thickness, a low modulus of elasticity, or a combination thereof. The roof section 82 may be made of a different plastic material than the wall section 84, and the wall section 84 may have reinforcing fibers and the roof section 82 may be free of reinforcing fibers.

FIG. 9 shows yet another embodiment. Toe cap 90 is generally similar to caps 12, 80 described above and includes a roof portion 92 and a wall portion 94. Unlike cap 80, cap 90 is made of a single plastic material with little or no reinforcing fibers.

Roof portion 92 to provide flexibility according to the invention
In this case, the wall thickness t is made small so that the roof part is easily deformed by compressive and impact loads, and the breaking stress is transferred to the wall part without acting on the roof part.
This is similar to that described above with respect to FIG. The thickness of the wall portion is, for example, approximately 6 mm, and the minimum thickness of the roof portion is approximately 1.5 mm.

The roof section 92 gradually increases in thickness away from the central plane 96 so that it smoothly continues into the front and side wall sections. The results of the compression and impact tests are shown as sample D in FIG. rectangle 6
6 and point 76 satisfy the required value.

FIG. 11 shows yet another embodiment of a toe cap 100. The roof portion 30 of the toe cap 100 is made flexible either by grooves as described for the toe cap 12 or by varying wall thickness or material as in the toe caps 80 or 90. Due to this flexibility, the roof portion bends when subjected to a load, and the load is transferred to the wall portions 32, 3.
4,36 so that it is supported. This toe cap 100 is connected to the toe cap 12 in the following points.
It is different from that. That is, its planar base is provided with a downwardly extending projection or ridge 102 at least in the area of the side wall sections 34, 36, and preferably also in the area of the front wall section 32. The protrusion 102 is seated on the sole of the finished shoe as shown in FIG. 1, and when subjected to an impact or compressive load, enters and securely engages the sole, causing the lateral wall portions 34, 36 to extend outwardly. Prevent it from spreading.

If the lateral wall sections expand outwardly under load, the strength of the toe cap will be reduced, the height in the midplane will be reduced, and the roof section will collapse excessively. The protrusion 102 prevents the wall portion from expanding by securing the base of the wall portion to the underlying sole. The sole acts to close the open bottom opening of the toe cap, thereby increasing the strength of the toe cap as a shell. Load transfer from the roof part to the wall part is thus carried out without unduly reducing the dimension between the roof part and the bottom.

The toe cap 100 is provided with a groove 104 which is asymmetrical with respect to the central plane 38 as a groove to provide flexibility to the roof section. To achieve optimum load transfer for a particular toe shape, asymmetrical grooves can be provided if desired to provide optimum flexibility in the roof section.

Although preferred embodiments of the present invention have been described above,
Various modifications and changes can be made within the scope of the present invention. Various plastic materials with or without reinforcing fibers can be used. To make the roof section flexible, the wall thickness may be controlled, the material may be changed, the roof section may be structurally different by grooves, through holes, etc. That is, the above embodiments are different illustrations and do not limit the present invention.

<Effects of the Invention> As described above, in the toe cap according to the present invention, the roof portion has greater flexibility than the side wall portion, so the roof portion easily deforms when subjected to compression and impact loads. It is distorted and flattened, and the load is transferred to the left and right side wall portions. Therefore, the load is mainly supported by these side wall portions, and the breaking stress due to the load is generated not in the roof portion but in the side wall portion. However, since the left and right side walls extending upward are capable of supporting a large load, the present invention can withstand compressive and impact loads that would have caused a fracture near the central plane area of the roof in a conventional cap. Even when the roof of the cap is applied, the side wall does not break, and only after receiving a larger load does the side wall break.

In other words, the present invention provides a toe cap that is stronger than conventional caps without increasing the overall wall thickness or adding reinforcing fibers (which have the disadvantage of increasing the weight of the cap). can be provided.

[Brief explanation of the drawing]

FIG. 1 is a side view showing a cross section of the toe portion of a safety shoe having a toe cap according to the present invention, FIG. 2 is a perspective view of the toe cap of FIG. 1, and FIG. 3 is a top plan view of the toe cap of FIG. 2. Figure 4 is a rear view of the toe cap in Figure 2, Figure 5 is a sectional view taken along the center plane in the front-rear direction, and Figure 6 is a view similar to Figure 4, but under a compressive load. FIG. 7 is a perspective view of another embodiment, and FIG. 8 is a perspective view of another embodiment.
9 is a rear view of yet another embodiment, FIG. 10 is a diagram showing the results of compression and impact tests for various toe caps A to D, and FIG. 11 is a rear view of the toe cap shown in FIG. FIG. 6 is a rear view of yet another embodiment. 12, 80, 90, 100: Toe cap, 3
0, 82, 92: Roof part, 34, 36, 84,
94: Side wall portion, 32: Front wall portion, 38, 96:
Central plane, 40, 42, 44, 46, 48, 5
0: groove, 104: groove, 102: protrusion, 26: opening.

Claims (1)

[Scope of Claims] 1. A toe cap attached to a shoe for providing structural reinforcement of the toe area against compressive and impact loads, the toe cap being made of plastic material and forming a pocket portion in the shape of the toe of the shoe. The shell body includes a shell body having a rearwardly facing opening 26 at the entrance of the pocket portion for putting in and taking out the toe, and the shell body includes a front wall portion 32, left and right side wall portions 34, 36, and a roof portion 30, which extends laterally from approximately the highest point in the longitudinally extending central plane 38 of the shell body to the left and right side wall portions 34, 36, and extending forward to a front wall portion 32, said lateral wall portions 34, 36 and said front wall portion 32;
connected to each other and continuous with the roof portion in a smooth curve, the front wall portion and the side wall portion extending upwardly from a generally planar base shaped to match the front portion of the sole; In the toe cap, the roof section transfers compressive and impact loads applied to the roof section laterally outwardly to the lateral wall section, such that the breaking stress due to the load is applied to the lateral wall section rather than to the roof section. characterized in that said configuration is provided by providing on the inner or outer surface of said roof section a series of grooves extending substantially parallel to said central plane;
Toe cap. 2. A toe cap attached to a shoe to provide structural reinforcement of the toe area against compressive and impact loads, comprising a shell body of plastic material in the shape of the toe of the shoe and forming a pocket; The shell body has a front wall portion, left and right side wall portions, and a roof portion 92. The roof portion 9
2 is a central plane 96 extending in the longitudinal direction of the shell body.
It extends in the transverse direction from approximately the highest part to the front, rear, left and right side wall portions, and extends forward to the front wall portion, and the side wall portion and the front wall portion are
connected to each other and continuous with the roof portion in a smooth curve, the front wall portion and the side wall portion extending upwardly from a generally planar base shaped to match the front portion of the sole; In the toe cap, the roof section transfers compressive and impact loads applied to the roof section laterally outwardly to the lateral wall section, such that the breaking stress due to the load is applied to the lateral wall section rather than to the roof section. The thickness of the roof portion is gradually reduced from the region adjacent to the side wall portion toward the region of the central plane 96, and the thickness of the roof portion is gradually reduced in the region of the central plane 96. A toe cap, characterized in that it is provided by a minimal design. 3. A toe cap attached to a shoe to provide structural reinforcement of the toe area against compressive and impact loads, the toe cap having a shell body of plastic material forming a pocket in the shape of the toe of the shoe; The shell body has a front wall portion, left and right side wall portions, and a roof portion 82. The roof portion 8
2 extends laterally from approximately the highest point in the longitudinally extending central plane of the shell main body to the left and right side wall portions, and extends forward to the front wall portion, and the side wall portion and the front wall portion are connected to each other and continuous with the roof portion in a smooth curve, the front wall portion and the side wall portion extending upwardly from a generally planar base shaped to match the front portion of the sole; In the toe cap, the roof section transfers compressive and impact loads applied to the roof section laterally outwardly to the lateral wall section, such that the breaking stress due to the load is applied to the lateral wall section rather than to the roof section. and that said configuration is provided by forming said roof portion from a plastics material having a greater flexibility than the plastics material forming said side wall portions. Features a toe cap.