JP2020090058A - Method for manufacturing footrest member, and footrest member - Google Patents

Abstract

To provide a method for manufacturing a step footrest member by coating a core metal with synthetic resin, without complications in the structure and control of a molding device, and provide a footrest member.SOLUTION: A core metal comprises a main body member having a rectangular cross section made of metal, and a metal sheet member that is fixed at both ends of the main body member, and has a hole that allows an end of a connection member of a step to be inserted through it. The sheet member is fixed to both ends of one of the four sides of the main body member, the core metal is placed in a molding recess of the lower mold, the peripheral part surrounding the hole of the sheet member of the core metal placed on the lower mold is held between a stepped portion of a stepped member provided to the lower mold and a holding member provided to the upper mold, and the molding space is filled with a synthetic resin for molding. In this way, a footrest member of the step is manufactured. The footrest member has high strength since the core metal is covered with a synthetic resin except the peripheral part of the hole in the ring-shaped portion of the sheet member of the core metal.SELECTED DRAWING: Figure 6

Description

The present invention relates to a method of manufacturing a footrest member for a step which is attached to a concrete wall of a manhole or a handhole, and a footrest member.

Steps are provided on the concrete walls of manholes and handholes for workers to move up and down in the halls.
Although there are various types of steps, a step including a connecting member and a footrest member is known (Patent Document 1).
An exploded plan, assembly plan and side view of this type of step is shown in FIGS. Here, 20 is a step, 21 is a foot hanging member, 24 is a connecting member for attaching the foot hanging member 2 to the concrete wall 100 at both ends of the foot hanging member 21, and 26 is an inner bracket embedded in the concrete wall 100. is there.

As shown in FIG. 11, the footrest member 21 has rising portions 22 at both ends thereof, and the rising portions 22 are formed with horizontally long through holes (long holes) 23. Further, as can be seen from FIG. 9, screw portions 25 and 26 are formed at both ends of the connecting member 24, and the inner bracket 27 is formed with a screw portion that is screwed into the screw portion 26 of the connecting member.

As can be seen from FIG. 10, one threaded portion 26 of the connection member 24 is screwed into the threaded portion of the inner bracket 27 embedded in the concrete wall 100 to attach the connection member 24 to the concrete wall 100, and the connection member By inserting the other screw portion 25 of 24 into the hole 23 of the footrest member 21 and tightening the protruding screw portion with the nut 28, the footrest member 21 can be attached to the connection member 24.
In this way, by attaching the connecting member 24 to the concrete wall 100 and attaching the foot hanging member 21 to the connecting member, the step 20 including the foot hanging member 21 and the connecting member 24 can be installed on the concrete wall 100.

As the footrest portion 21 of the step, those made of only synthetic resin have been widely used, but the strength and service life are not sufficient, and the footrest portion 21 is deteriorated and damaged during repeated ascent and descent, which may cause damage to workers. I was having trouble getting up and down.
Various methods have been adopted to increase the strength of synthetic resin products manufactured by injection molding, and one of them is a synthetic resin product with high strength obtained by coating a stainless steel core with a synthetic resin material. There is a method of manufacturing.

Conventionally, in order to coat a core metal with a synthetic resin, the core metal is floated in a molding space formed by a lower mold and an upper mold of a molding apparatus, and the synthetic resin is supplied to the outer periphery of the core metal (Patent Reference 2). However, in this conventional method, in order to make the core metal in a floating state, a plurality of pistons for fixing the core metal are inserted between the lower mold and the upper mold, and a plurality of pistons are arranged from the lower mold to the upper mold. The pin must be inserted to make the core metal float, and the structure of the mold of the injection molding apparatus and the control of the apparatus are complicated.

JP 2001-81797 A JP-A-2003-3505

The present invention has been made in view of the above problems of the prior art, and solves the above problems of the prior art in a method of manufacturing a footrest member made of a synthetic resin having a step metal core. It is an object of the present invention to provide a method for manufacturing a high-strength footrest member by coating a core metal with a synthetic resin, and a high-strength footrest member having the core metal.

In order to solve the above problems, the present invention employs the following means.
[1] In a method of manufacturing a stepping member of a step by placing a core metal in a molding space of a molding die including a lower mold and an upper mold, and then filling the molding space with a synthetic resin to mold, Is composed of a metal main body member having a rectangular cross section and a metal thin plate member having a hole through which an end portion of a step connecting member can be inserted, and the thin plate member is one of four side surfaces of the main body member. A stepped member, which is fixed to both ends of the side surface and has a stepped portion on which a peripheral edge portion surrounding the hole of the thin plate member can be mounted, is provided on the molding concave surface of the lower die. The stepped portion of the stepped member is provided with a pressing member that can be brought into contact with the peripheral edge portion surrounding the hole of the thin plate member of the core metal when the molding die is clamped. The stepped portion of the stepped member and the pressing member of the upper die hold the peripheral edge portion surrounding the hole of the thin plate member of the core metal, and the synthetic resin is filled into the molding space of the die and molded. A method for manufacturing a footrest member according to the above step.
[2] A main member made of a metal having a rectangular cross section, and a hole fixed to both ends of one of the four side faces of the main member and through which the end of the step connection member can be inserted. A stepping member, characterized in that the periphery of the main body member of the cored bar made of the metal thin plate member and the periphery of the portion of the thin plate member excluding the peripheral portion of the hole are covered with synthetic resin.
[3] The method for producing a footrest member according to [2], wherein the thin plate member of the core metal is made of stainless steel.

According to the method of the present invention, the peripheral portion surrounding the hole through which the end portion of the connecting member of the step formed on the thin plate member of the core metal is formed by the stepped portion of the lower die stepped member and the upper die pressing member. Since it is sandwiched and the main part including the main body of the core metal is floated in the molding space formed by the lower and upper molds and filled with synthetic resin, it is complicated without using a molding device with a complicated structure. It is possible to manufacture a footrest member made of a synthetic resin having a core metal without performing various controls and operations. Further, since the footrest member of the present invention is covered with the synthetic resin around the main body member of the core metal and the periphery of the portion of the thin plate member excluding the peripheral edge portion of the hole, compared with the footrest member made of only the synthetic resin. It has high strength.

The front view of the metal core in embodiment of this invention is shown. The side view of the core metal in the embodiment of the present invention is shown. 3 shows a thin plate member fixed to a main body member of a cored bar in an embodiment of the present invention. The front view of the footrest member of this invention is shown. The top view of the lower mold of an injection molding device is shown. The perspective view of the lower mold (part) of an injection molding device is shown. The perspective view of the upper mold of an injection molding device is shown. The whole core metal arrange|positioned in the shaping|molding space of a shaping|molding die is shown. 3 shows a portion of a cored bar including one thin plate member, which is arranged in a molding space of a molding die. Exploded plan view of steps Assembly plan of step The front view of a step is shown.

Embodiments of the present invention will be specifically described below with reference to the drawings.
1 and 2 show a core metal used in a method for manufacturing a footrest member according to an embodiment of the present invention by an injection molding machine.
The core metal 1 includes a metal main body member 2 and a metal thin plate member 3 connected to both ends of the main body member. The main body member 2 has a rectangular cross section (see FIG. 2).
As can be seen from FIG. 3, the thin plate member 3 includes a base portion 4 and a ring-shaped portion 5 in which holes are formed. Although this hole is not circular but is horizontally long in FIG. 1, it is not limited to this shape. The threaded end of the connecting member is inserted through this hole when the step is attached to the concrete wall (see FIGS. 9-11). Fine corrugations may be formed on the outer periphery of the hole so that the inserted connecting member does not slip inside the hole.

The thin plate member 3 is fixed to each of both end portions of one of the four side surfaces of the main body member 2 by spot welding (two locations in FIG. 1) or the like at the base portion 4. At this time, as shown in FIG. 3, the end portion of the main body member 2 is joined to the base portion 4 so as not to overlap the ring-shaped portion 5 of the thin plate member 3.

As will be described later, in the footrest member 18 having a cored bar manufactured by the method of the present invention, the main body member 2 of the cored bar is covered with a synthetic resin, and the thin plate member 3 also has a peripheral edge part surrounding the hole of the ring-shaped part 5. The part to be removed is covered with synthetic resin. FIG. 4 shows a footrest member 18 manufactured by the method of the present invention. In this figure, the outline of the portion of the cored bar covered with the synthetic resin is shown by a broken line.

The lower mold and the upper mold that compose the molding die of the injection molding apparatus for carrying out the present invention will be described.
The lower mold and the upper mold are each provided with a molding concave surface, and the molding concave surface of the lower mold and the molding concave surface of the upper mold face each other to form a molding space corresponding to the shape of the footrest member. ..
FIG. 5 shows a plan view of the molding concave surface 7 formed on the lower mold 6. The planar shape of the molding concave surface corresponds to the plan view shape (see FIG. 4) of the footrest member. In this figure, the stepped member 8 attached to the molding concave surface 7 is shown. The stepped member 8 will be described later.
A similar molding concave surface 14 is also formed on the upper mold 13 (see FIG. 7). A pressing member 15 is attached to the molding concave surface 14 of the upper mold 13. The pressing member 15 will be described later.

At the bottom of the molding concave surface 7 of the lower mold 6, when the core metal 1 is arranged on the molding concave surface 7 of the lower mold 6, a step is formed at a position corresponding to the hole of the ring-shaped portion 5 of the thin plate member 3 of the core metal 1. A stepped member 8 having an attachment 9 is attached.
Since the thin plate member 3 of the core metal 1 is attached to both ends of the main body member 2, two stepped members 8 are attached to the lower mold. FIG. 6 shows a perspective view of the lower mold 6 (portion) to which the one step member 8 is attached.

The ring-shaped portion 5 of the thin plate member 3 can be mounted on the stepped portion 9 of the stepped member 8. That is, the stepped member 8 is composed of a lower portion 10 and an upper portion 11, and the upper portion 11 has a shape similar in cross section to a hole formed in the ring shape 5, and the cross-sectional area is smaller than the area of the hole. The lower portion 10 is slightly smaller and has a cross-section similar to the hole formed in the ring-shaped portion 5, and the cross-sectional area is larger than the area of the hole. Therefore, it is possible to form the stepped portion 9 on the peripheral portion of the upper surface of the lower portion 10 by superposing the upper portion 11 on the lower portion 10, and to mount the ring-shaped portion 5 of the thin plate member 3 on the stepped portion 9. You can
The stepped member 8 may be a combination of the lower portion 10 and the upper portion 11 or a combination of the lower portion 10 and the upper portion 11.

As can be seen from FIG. 5, two such stepped members 8 are attached to the molding concave surface of the lower die 6, so that the stepped member 8 is formed in the hole formed in the ring-shaped portion 5 of the thin plate member 3. The ring-shaped portion 5 of the thin plate member 3 can be mounted on the stepped portion 9 of the stepped member 8 by inserting the upper portion 12 of the.
The stepped member 8 can be attached to the lower mold 6 with a bolt or the like. The hole 12 formed in the stepped member 8 is a hole for inserting a bolt, and will be filled with a bolt (not shown) after being attached to the lower mold of the stepped member 8.

There are two methods for mounting the cored bar 1 on the stepped portion 9 of the stepped member 8. That is, it is placed on the stepped portion 9 with the main body member 2 facing down and the thin plate member 3 facing up, or on the stepped portion 9 with the main body member 2 facing up and the thin plate member 3 facing down. There are two methods of mounting.
When the cored bar 1 is placed on the stepped portion 9 with the main body member 2 facing down and the thin plate member 3 facing up, the lower portion 10 of the stepped member 8 has a lower surface of the main body member 2 of the lower mold 6. It has a height that does not contact the bottom surface of the molding concave surface 7 (see FIGS. 8A and 8B).
Further, when the core metal 1 is placed on the stepped portion 9 with the main body member 2 facing upward and the thin plate member 3 facing downward, and a molding space is formed by the lower mold 6 and the upper mold 13 described later, The upper portion 11 of the stepped member 8 has a height such that the upper surface of the main body member 2 does not contact the bottom surface of the molding concave surface 14 of the upper mold 13.

The upper mold 13 is provided with a molding concave surface 14 on the surface facing the molding concave surface 7 of the lower mold 6. A pressing member 15 is attached to the bottom surface of the molding concave surface 14 of the upper die 13 at a position facing the stepped member 8 attached to the molding concave surface 7 of the lower die 6. FIG. 7 shows a perspective view of the upper mold 13 (portion) to which the pressing member 15 is attached.
Since the thin plate member 3 of the core metal 1 is attached to each of both ends of the main body member 2, two pressing members 15 are attached to the upper mold 13.

The pressing member 15 has a cap-like (lid-like) shape, a peripheral edge portion 16 rises, and a concave portion is formed inside thereof. The cross section of this recess is similar in shape to the cross section of the upper part 11 of the lower stepped member 8 and is slightly larger than the area of the cross section of the upper part 11. Therefore, when the lower die 6 and the upper die 13 are clamped to form a molding space, the upper portion 11 of the stepped member 8 of the lower die is inserted into the recess of the pressing member 15.
In either of the two methods of mounting, the concave portion of the pressing member 15 is formed from the height of the upper portion 11 of the stepped member 8 attached to the lower mold 6 to the ring-shaped portion 5 of the thin plate member 3 of the core metal 1. It has a depth less the thickness [see FIG. 8(b)].
The pressing member 15 can be attached to the upper mold with a bolt or the like. The hole 17 formed in the pressing member is a hole for inserting a bolt, and will be filled with a bolt (not shown) after the pressing member 15 is attached to the upper mold 13.

Therefore, the ring-shaped portion 5 of the thin plate member 3 fixed to both ends of the main body member 2 of the core metal 1 is attached to the stepped portion 9 of the stepped member 8 provided near both ends of the molding concave surface 7 of the lower die 6. When the lower die 6 and the upper die 13 are clamped to form a molding space, the stepped portion 9 of the stepped member 8 attached to the lower die 6 and the periphery of the pressing member 15 of the upper die 13 are mounted. Since the peripheral portion surrounding the hole of the ring-shaped portion 5 of the thin plate member 3 is sandwiched between the portion 16 and the portion 16, as can be seen from FIG. 8A, the main portion of the core metal 1 including the main body member 2 (core metal 1 (Excluding the peripheral portion surrounding the hole of the ring-shaped portion 5 of the thin plate member 3) can be supported in a floating state in the molding space formed by the lower mold 6 and the upper mold 13 of the mold that is clamped. .
In FIGS. 8A and 8B, the core metal 1 is mounted on the stepped portion 8 with the main body member 2 facing downward and the thin plate member 3 facing upward. When the core metal 1 is mounted on the stepped portion 9 with the main body member 2 facing upward and the thin plate member 3 facing downward, the stepped portion 9 is placed at a position more than that shown in FIGS. 8(a) and 8(b). Is also below.

In this state, when the synthetic resin is filled from a gate (not shown) which is a synthetic resin supply port formed at the boundary between the lower mold and the upper mold, the synthetic resin is supplied to the molding space and the thin plate member of the core metal 1 Portions other than the peripheral portion surrounding the hole of the ring-shaped portion 5 can be covered with the synthetic resin.
At this time, the core metal 1 is supported by being sandwiched between the stepped member 8 and the pressing member 15 peripheral portion 16 at the peripheral portion surrounding the hole of the ring-shaped portion 5 of the thin plate member 3 fixed to both ends of the main body member 2. Since the core metal 1 hardly moves and the flow of the synthetic resin is not obstructed during the filling of the synthetic resin, the edge of the hole of the ring-shaped part 5 of the thin plate member 3 of the core metal 1 is prevented. The parts other than can be reliably covered with the synthetic resin.

As can be seen from FIG. 4, in the footrest member 18 manufactured according to the present invention, the main body member 2 of the core metal 1 is covered with the synthetic resin, and the thin plate member 3 also excludes the peripheral portion surrounding the hole of the ring-shaped portion 5. The site is covered with synthetic resin. Then, the upper portion of the stepped member 8 provided on the lower die 6 penetrates the hole portion of the ring-shaped portion 5 of the thin plate member 3 and is inserted into the concave portion of the pressing member 15 provided on the upper die 13. Therefore, the holes 23 through which the ends of the connecting member 24 can be inserted are formed at both ends of the footrest member 21.

When the step 20 is attached to the concrete wall 100 of the manhole or the handhole, one end of the connection member 24 on which the thread groove is formed is screwed into the inner bracket 27 provided on the concrete wall 100, and then the footrest is attached. The other end of the connecting member 24, in which the other thread groove is formed, is inserted into the hole 23 of the member 18, and the end protruding from this hole is tightened with a nut. Can be attached to a concrete wall (see Figures 9-11).

In the footrest member which does not have a core metal and is made of only synthetic resin, the synthetic resin layer at the peripheral portion of the hole through which the connecting member is inserted becomes thin, so that the strength of this portion is weak.
In the footrest member of the present invention, since the peripheral edge portion surrounding the hole formed in the ring-shaped portion 5 of the thin plate member of the core metal 1 is exposed without being covered with the synthetic resin, the peripheral edge portion made of high-strength metal. The part is supported by the connecting member 24. As described above, in the footrest member of the present invention, since the connecting member 24 is supported by the ring-shaped portion 5 of the metal cored bar, both end portions of the footrest member in which the holes through which the connecting member 24 is inserted are formed. Can also have high strength, and the entire footrest member can have high strength.

In the footrest member of the present invention, since the core metal other than the peripheral edge portion of the hole of the ring-shaped portion of the core metal thin plate member is covered with the synthetic resin, the strength is improved as compared with the footrest member formed of only the synthetic resin. In addition, since both end portions of the foot hanging member in which the hole through which the connecting member is inserted are formed can also have high strength, it is possible to manufacture a product that can sufficiently withstand repeated up and down movements of the worker.

For manholes and handholes in a corrosive atmosphere, it is desirable that the core metal be made of a metal having good corrosion resistance such as stainless steel (for example, austenitic stainless steel such as SUS304).
Corrosion does not easily progress in the portion of the cored bar covered with the synthetic resin, so that the main body member 2 of the cored bar 1 is suppressed by the coating of the synthetic resin. Therefore, the main body member 2 of the core metal 1 may be made of ordinary steel, and the thin plate member 3 of which a part is exposed may be made of stainless steel having excellent corrosion resistance.

1: core metal 2: body member 3: thin plate member 4: base of thin plate member 5: ring-shaped part of thin plate member 6: lower mold 7: molding concave surface of lower mold 8: stepped member 9: stepped member of stepped member Part 10: Lower part of stepped member 11: Upper part of stepped member 12: Bolt insertion hole formed in the stepped member 13: Upper mold 14: Molded concave surface of upper mold 15: Pressing member 16: Peripheral part of pressing member 17: Bolt insertion hole of the pressing member 18: Foot hanging member having a cored bar

20: Step 21: Foot hanging member 22: Standing portion of foot hanging member 23: Hole of foot hanging member 24: Connection member 25: Screw portion formed at one end of the connection member 26: Formed at the other end of the connection member Screw part 27: inner bracket 28: nut 100: concrete wall such as manhole

Claims (3)

In the method for manufacturing the footrest member of the step, by disposing the core metal in the molding space of the molding die composed of the lower die and the upper die, and then filling the molding space with the synthetic resin and molding.
The core metal is composed of a metal main body member having a rectangular cross section and a metal thin plate member having a hole through which an end portion of the step connecting member can be inserted, and the thin plate member is one of four side surfaces of the main body member. Fixed to both ends of one side of
A stepped member having a stepped portion on which a peripheral portion surrounding the hole of the thin plate member can be mounted is provided on the molding concave surface of the lower mold,
On the molding concave surface of the upper mold, the peripheral portion surrounding the hole of the thin plate member of the core bar is mounted on the stepped portion of the stepped member provided on the lower mold, and when the molding die is clamped, the peripheral portion is abutted. Providing a pressing member that can contact,
The stepped portion of the stepped member of the lower die and the pressing member of the upper die hold the peripheral edge portion surrounding the hole of the thin plate member of the core metal and fill the molding space of the die closed with synthetic resin. A method of manufacturing a footrest member, the method comprising the steps of: A metal body in which the footrest member is made of metal and has a rectangular cross section, and a hole which is fixed to both ends of one of the four side surfaces of the body member and through which the end of the connecting member of the step can be inserted. A footrest member for a step, characterized in that a periphery of a main body member of a cored bar made of a thin plate member made of metal and a periphery of a portion of the thin plate member excluding a peripheral portion of a hole are covered with a synthetic resin. The stepping member according to claim 2, wherein the thin plate member of the core metal is made of stainless steel.

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