Resin component and method for manufacturing resin component

Abstract

To provide a method for manufacturing a resin-made component and a resin-made product capable of ensuring the strength of the resin-made product by an insert member without bringing about peeling or destruction and capable of suppressing jetting generated at the time of molding and the lowering of the density of a thick-walled part by the insert member.SOLUTION: The piston 6 is provided with a shaft part 6a and a first flange part 6a formed in a diameter larger than that of the shaft part 6d, and is integrally provided with an insert member 13 inside. The insert member 13 includes a center piece side 6a (face part) crossing the center shaft CL1 of the shaft part side 13a, and claw part side 13a and side 6d extending from the center piece side 13b and abutting on the outer end face of the first flange part side 13b from the inside, and the claw part side 13b and side 13b are provided symmetrically with respect to the center shaft of the shaft part side. 6a CL1. An injection gate trace 13a derived from the injection gate 22 is formed at one end of the shaft part 6a facing the center piece 6p.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a resin part and a method for manufacturing a resin part. [Background technology]

[0002] Conventionally, in order to ensure strength, resin pistons (resin parts of the present invention) used in master cylinder devices for bar-handle vehicles have been formed by loading a cylindrical or disk-shaped metal insert member into a mold during molding, and then injecting and solidifying the resin (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-205793 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the resin piston of the above-mentioned Patent Document 1, the metal insert member protrudes outward, and although the metal bears the load and ensures the strength of the resin piston, the structure is susceptible to peeling or breakage at the adhesive boundary due to the difference in rigidity between the metal and resin.Furthermore, if peeling or breakage occurs, there is a high possibility that it will lead to a malfunction.

[0005] Furthermore, when molding a resin piston, there is a risk of jetting occurring near the resin injection gate, and of density reduction due to the generation of voids in the thick wall portion.

[0006] Therefore, the present invention aims to provide a method for manufacturing a resin part and a resin product that uses an insert member to ensure the strength of the resin product without causing peeling or destruction at the adhesive boundary, and that also uses the insert member to suppress jetting that occurs during molding and a decrease in density in thick sections. [Means for solving the problem]

[0007] In order to achieve the above object, the resin part of the present invention is a resin part comprising a shaft portion and a flange portion formed with a larger diameter than the shaft portion, with an insert member integrally provided inside, wherein the insert member comprises a surface portion that intersects the central axis of the shaft portion and claw portions that extend from the surface portion and abut against the outer end surface of the flange portion from the inside, the claw portions being arranged symmetrically or radially with respect to the central axis of the shaft portion, and injection gate marks resulting from the resin injection gate being formed at one end of the shaft facing the surface portion.

[0008] Furthermore, the manufacturing method of a resin part of the present invention is a manufacturing method of a resin part in which an insert member is integrally molded inside one end side of a shaft portion, and is characterized in that an injection gate is provided at one end of the shaft portion for injecting resin into the cavity of a molding die, and the insert member faces the injection gate and has a surface portion perpendicular to the direction of resin injection, and a claw portion extending from the surface portion and abutting against the molding die, and resin is injected from the injection gate with the claw portion abutting against the molding die to fix the insert member in the cavity. [Effects of the Invention]

[0009] According to the resin part and the manufacturing method of the resin part of the present invention, the insert member ensures the strength of the resin product without causing peeling or breakage. Furthermore, the insert member allows the resin to flow smoothly during molding, suppressing jetting that occurs during molding and density loss in thick sections. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a side view of a resin piston showing a first embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II of FIG. [Figure 3] 1 is a plan view of a resin piston showing a first embodiment of the present invention. [Figure 4]1 is a perspective view of an insert member showing a first embodiment of the present invention. [Figure 5] FIG. 2 is a schematic diagram illustrating a resin piston during molding. [Figure 6] 6 is a cross-sectional view taken along the line VI-VI in FIG. 7. [Figure 7] 1 is a plan view of a master cylinder device using a resin piston according to a first embodiment. [Figure 8] 1 is a perspective view of a master cylinder device using a resin piston according to a first embodiment. [Figure 9] FIG. 10 is a perspective view of an insert member showing a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] 1 to 8 are diagrams showing a first embodiment in which a resin part according to the present invention is applied to a resin piston of a master cylinder device used in a bar handle vehicle.

[0012] 6 to 8, the master cylinder device 1 is mounted on a handlebar (not shown) at the front of a bar-handle vehicle for steering the front wheels, and includes a master cylinder 2 and a brake lever 3. The master cylinder 2 is attached to the vehicle body by holding the handlebar with vehicle body mounting portions 2b, 2b formed on the cylinder body 2a and a clamp 4 and fastening them with bolts. The brake lever 3 is inserted between a pair of upper and lower lever holders 2c, 2c that protrude toward the front of the vehicle body of the cylinder body 2a, and is rotatably held in the lever holders 2c, 2c by a pivot 5.

[0013] A cylinder body 2a of the master cylinder 2 is provided with a bottomed cylinder bore 2d that opens toward the front of the vehicle body. A resin piston 6 (a resin part of the present invention) is inserted into the cylinder bore 2d via a first cup seal 7a and a second cup seal 7b. A hydraulic chamber 8 is defined between the resin piston 6 and the bottom of the cylinder bore 2d, and a union hole 8a is provided at the bottom of the cylinder bore 2d. A guide pin 9 that protrudes in the cylinder axial direction is provided at the center of the bottom of the cylinder bore 2d. Furthermore, a reservoir 10 that supplies hydraulic fluid to the cylinder bore 2d is provided at the top of the cylinder body 2a.

[0014] The brake lever 3 is divided into a lever body 3a, which is operated on the handlebar at the front of the vehicle body, and a knocker 3b, and by rotating the lever body 3a, the knocker 3b pushes the push rod 11. The push rod 11 has a spherical head 11a that abuts against a resin piston 6, and by rotating the lever body 3a, the resin piston 6 is actuated via the knocker 3b and the push rod 11.

[0015] As shown in Figures 1 to 3, the resin piston 6 includes a shaft portion 6a, a cylindrical portion 6b extending from one end of the shaft portion 6a toward one end along a central axis CL1 of the shaft portion 6a, and a push rod accommodating portion 6c extending from the other end of the shaft portion 6a toward the other end along the central axis CL1.

[0016] The shaft portion 6a is provided with a first flange portion 6d (the flange portion of the present invention) formed with a larger diameter than the shaft portion 6a between the shaft portion 6a and the push rod accommodating portion 6c. The first flange portion 6d is chamfered twice to form chamfered portions 6e, 6e to avoid sliding contact with the cylinder bore 2d.

[0017] The cylindrical portion 6b is formed with the following in order from the other end to the one end: a large-diameter shaft portion 6f formed with a diameter larger than that of the shaft portion 6a but smaller than that of the first flange portion 6d, a second flange portion 6g formed with the same diameter as that of the first flange portion 6d, a small-diameter shaft portion 6h formed with a diameter smaller than that of the shaft portion 6a, and a small-diameter flange portion 6i formed with a diameter larger than that of the shaft portion 6a but smaller than that of the large-diameter shaft portion 6f. A first cup seal 7a is attached to the small-diameter shaft portion 6h, and a second cup seal 7b is attached to the shaft portion 6a.

[0018] Furthermore, a guide hole 6j in the cylinder axial direction is formed inside the cylindrical portion 6b and opens to one end side. A return spring 12 is disposed between a bottom surface 6m of the guide hole 6j and the base of the guide pin 9, and the elastic force of the return spring 12 urges the resin piston 6 toward the other end side (the cylinder hole opening side) when it is not in operation.

[0019] The push rod accommodating portion 6c has an outer diameter the same as that of the small diameter flange portion 6i, and is formed therein with a spherical recess 6k that opens to the other end side, with the head 11a of the push rod 11 abutting against the spherical recess 6k.

[0020] 2 and 4, an insert member 13 is integrally provided inside the resin piston 6. The insert member 13 is made of a high-strength material, such as steel, that is elastic with respect to the base resin, and includes a central piece 13a (a surface portion of the present invention) that is placed inside the shaft portion 6a, and a pair of claw portions 13b, 13b that extend from both ends of the central piece 13a and are formed symmetrically with respect to the central axis CL1.

[0021] The central piece 13a is disposed on the shaft 6a between the push rod accommodating portion 6c and the guide hole 6j so that one side surface 13c is perpendicular to the central axis CL1 of the shaft 6a. An injection gate mark 6p resulting from the resin injection gate is formed in the center of the bottom surface 6m (one end of the shaft 6a) of the guide hole 6j facing the one side surface 13c.

[0022] The claws 13b extend from both ends of the central piece 13a and include first claws 13d whose tips are located inside the outer end surface 6n of the first flange 6d on the other axial end side, and second claws 13e that abut from the inside against the outer end surface of the chamfered portion 6e of the first flange 6d. The second claws 13e have exposed surfaces on parts of the outer end surfaces of the chamfered portions 6e. Furthermore, the central piece 13a and the claws 13b are elastic enough to deform to some extent in response to the resin.

[0023] Next, a method for manufacturing the resin piston 6 described above will be described with reference to FIG. 5. The mold 21 used to mold the resin piston 6 has an injection gate 22 for injecting resin at the center of the bottom surface forming portion 21a that forms the bottom surface 6m of the guide hole 6j. The insert member 13 is placed in the mold 21 so that one side surface 13c of the central piece 13a faces the injection gate 22 and is perpendicular to the resin injection direction A, and the second claws 13e, 13e abut against the chamfer forming portions 21b, 21b of the mold 21 to fix the insert member 13 in the cavity 21c. Next, resin is injected into the cavity 21c through the injection gate 22 to mold the insert member 13.

[0024] At this time, the resin injected from injection gate 22 hits one side surface 13c of center piece 13a and spreads along first claws 13d, 13d, filling cavity 21c. This prevents the resin inflow path from expanding suddenly, preventing a decrease in density and suppressing the occurrence of voids. Furthermore, by preventing the resin from flowing straight through injection gate 22, it is possible to prevent the resin from meandering in the thick-walled portion and making it easier for the resin to spread radially, thereby suppressing the occurrence of jetting.

[0025] After the resin filled in cavity 21c has solidified, resin piston 6 is released from the mold and unnecessary portions such as injection gate 22 are cut off. In the molded resin piston 6, the injection gate mark 6p that remains after injection gate 22 is cut off is formed.

[0026] In the master cylinder device 1 configured as described above, when the brake lever 3 is rotated, the knocker 3b pushes the resin piston 6 toward the bottom of the cylinder bore 2d via the push rod 11. The resin piston 6 accommodates the guide pin 9 in the guide hole 6j and moves toward the bottom of the cylinder bore 2d while compressing the return spring 12, causing the hydraulic fluid in the hydraulic chamber 8 to rise and be supplied to the brake via the union hole 8a, thereby braking the front wheels.

[0027] During braking, a load is applied to the spherical recess 6k and shaft portion 6a of the resin piston 6, which are pressed by the push rod 11, but strength can be ensured because the insert member 13, made of steel, is located inside the shaft portion 6a between the push rod accommodating portion 6c and the guide hole 6j. Furthermore, because the insert member 13 is made of steel, which is a high-strength material and has elasticity compared to the base resin, the strength of the resin piston 6 can be reliably improved.

[0028] Moreover, since most of the insert member 13 is molded into the resin piston 6, except for the surfaces of the second claw portions 13e, 13e that are exposed to the outside, there is no risk of peeling or breaking at the adhesive boundary between the insert member 13 and the resin piston 6. Furthermore, the insert member 13 makes it difficult for the resin piston 6 to deform, and it is possible to reduce the stress that resists deformation.

[0029] FIG. 9 shows an insert member 31 according to a second embodiment of the present invention, and components similar to those in the first embodiment are given the same reference numerals, and detailed descriptions thereof will be omitted.

[0030] The insert member 31 of this embodiment has a central piece 31a formed in a cross shape and four claw portions 13b extending from the four pieces of the central piece 31a. Furthermore, the four claw portions 13b are formed radially with respect to the central axis CL1 of the shaft portion 6a.

[0031] The insert member 31 is placed in the mold 21 and molded in the same manner as the insert member 13 of the first embodiment. At this time, the resin injected from the injection gate 22 hits one side surface 31b of the central piece 31a and spreads along the four first claw portions 13d to fill the cavity 21c.

[0032] Next, using the same mold 21, a resin piston without an insert member molded therein (comparison example), a resin piston with the insert member 13 of the first embodiment molded therein (Example 1), and a resin piston with the insert member 31 of the second embodiment molded therein (Example 2) were manufactured, and the density distribution of the resin was analyzed.

[0033] In the resin piston of the comparative example, the density of the shaft portion 6a between the push rod accommodating portion 6c and the guide hole 6j and the density of the first flange portion 6d were reduced. In the resin piston of Example 1, there were portions with reduced density in a part of the shaft portion 6a between the push rod accommodating portion 6c and the guide hole 6j, and in a part of the first flange portion 6d. In the resin piston of Example 2, there was no portion where the density was reduced.

[0034] Thus, the decrease in density was suppressed in the resin pistons of Examples 1 and 2, which were provided with the insert members 13 and 31. Furthermore, the resin piston of Example 2, which was provided with the insert member 31 having a cross-shaped central piece, was able to suppress the decrease in density more effectively than the resin piston of Example 1, which was provided with the insert member 13 having a straight-shaped central piece.

[0035] The present invention is not limited to the above-described embodiment, and the surface of the second claw exposed at the chamfered portion may be coated with resin. Furthermore, the tip of the first claw may be abutted against the axial outer end surface of the first flange from the inside. Furthermore, the number of claws may be even or odd, as long as they are arranged symmetrically or radially about the central axis of the shaft. [Explanation of symbols]

[0036] 1...master cylinder device, 2...master cylinder, 2a...cylinder body, 2b...vehicle body mounting portion, 2c...lever holder, 2d...cylinder hole, 3...brake lever, 3a...lever main body, 3b...knocker, 4...clamp, 5...pivot, 6...resin piston, 6a...shaft portion, 6b...tubular portion, 6c...push rod accommodating portion, 6d...first flange portion, 6e...chamfered portion, 6f...large diameter shaft portion, 6g...second flange portion, 6h...small diameter shaft portion, 6i...small diameter flange portion, 6j...guide hole, 6k...spherical recess, 6m...bottom surface, 6n...outer end surface, 6p...injection gate mark, 7a...first cup seal, 7b...second cup seal, 8...hydraulic chamber, 8a...union hole, 9...guide pin, 10...reservoir, 11...push rod, 11a...head, 12...return spring, 13...insert member, 13a...center piece, 13b...claw portion, 13c...one side surface, 13d...first claw portion, 13e...second claw portion, 21...mold, 21a...bottom surface forming portion, 21b...chamfer forming portion, 21c...cavity, 22...injection gate, 31...insert member, 31a...center piece, 31b...one side surface

Claims

1. A resin part having a shaft portion and a flange portion formed with a diameter larger than that of the shaft portion, and having an insert member integrally provided therein, The insert member includes a surface portion intersecting the central axis of the shaft portion, and a claw portion extending from the surface portion and abutting against an outer end surface of the flange portion from the inside. The claws are provided symmetrically or radially with respect to the central axis of the shaft, A resin part characterized in that an injection gate mark resulting from a resin injection gate is formed on one end of the shaft portion facing the face portion.

2. The resin part according to claim 1, characterized in that the claw portion comprises a first claw portion that abuts the axial outer end surface of the flange portion from the inside, and a second claw portion that abuts the outer peripheral surface of the flange portion from the inside.

3. The resin part according to claim 1 or 2, characterized in that the resin part is a piston for a master cylinder, and comprises a tubular portion extending from one end of the shaft portion along the central axis, and a push rod accommodating portion extending from the other end of the shaft portion.

4. A method for manufacturing a resin part in which an insert member is integrally molded inside one end side of a shaft portion, an injection gate for injecting resin into a cavity of the molding die is provided at one end of the shaft portion; the insert member has a surface portion that faces the injection gate and is perpendicular to the direction of injection of the resin, and a claw portion that extends from the surface portion and abuts against the molding die; A method for manufacturing a resin part, characterized in that the claw portion is brought into contact with the molding die to fix the insert member in the cavity, and resin is injected through the injection gate.

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