JPH054255A - Insert molding method of transmission member - Google Patents

Abstract

PURPOSE:To provide the insert molding method of transmission member, the transmission contact surface strength of which is high and the mechanical strength and reliability of a part of which are improved. CONSTITUTION:In the insert molding method of transmission member concerned, an insert member 4, in the interior of which a sprue or runner 4A having a cold slug well part 4C at its tip or terminal and at the portion covering with resin after molding of which one or a plurality of gates 4B are formed, is employed so as to feed resin under molten state through the sprue or runner 4A and the gates 4B of the insert member 4 into a mold 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for insert molding a transmission member.

[0002]

BACKGROUND OF THE INVENTION A transmission member means a member that two or more members come into contact with each other to transmit power as they are or converted from one to the other by mutual frictional force, and specifically, gears and cams. , Friction wheel, ratchet wheel, chain wheel, star wheel, escape wheel, roller, pulley, pulley, etc. Conventionally, when molding these transmission members with different materials for the shaft or bearing and the transmission contact surface portion, insert molding is performed with the shaft or bearing portion as the insert member and the transmission contact surface portion as the resin molding portion. The molding method is performed as described in JP-A-2-41222.

According to such an insert molding method, a part of the resin injected from the gate passes through the resin passage in the insert member to form the resin molded portion. Therefore, the insert member is inserted into the resin molded portion in a later step. Compared to things
It is possible to obtain a transmission member in which the resin molding portion and the insert member have a high degree of integration and whose relative position is less displaced.

According to such a conventional insert molding method,
The insert member is automatically or semi-automatically set in advance in the mold and is molded in the mold corresponding to the surface of the resin molding part, that is, the mold having the gate on the outer peripheral surface of the cavity (see FIG. 7).

[0005]

However, in the above-described conventional molding method, when the cooled resin at the tip of the resin injection nozzle is injected into the cavity, it causes defects such as flow marks and short shots. In particular, in terms of the function as a transmission member, when the cooled resin is sent to the transmission contact surface, which is the most important, not only the strength of the transmission contact surface decreases, but also the absolute mechanical strength as a transmission member and It has a serious drawback that no reliability of parts can be obtained.

Further, since the mold is formed by a mold having a gate provided on the outer peripheral surface of the cavity, a gate mark remains on the surface of the resin molding portion, and therefore a post-treatment process such as cutting and polishing of the gate mark is required. Not only that, but depending on the degree of cutting and polishing, the parallelism and flatness of the surfaces may be impaired, the finished dimensions may be misaligned, and weld lines may remain, resulting in a decrease in strength. have.

The gate has a great influence on the dimensional accuracy and strength of the resin molding portion depending on conditions such as the position, number and shape of the gate. It is necessary to determine the optimum design conditions based on analysis etc. so that the maximum strength of the entire product can be obtained.

However, in the conventional mold, various conditions other than the gate, such as the position of the spool or the runner, the position of the insert member, the ease of cutting and polishing during the post-treatment process, etc., can be satisfied. Since the mold design conditions are determined in consideration, the gate position on the outer peripheral surface of the cavity cannot be said to be an ideal position in terms of dimensional accuracy and strength. It is said that the resin flow becomes uneven and uneven as shown by the arrow Y, or a weld line is generated, so that the dimensional stability and accuracy of the resin molding portion and the mechanical strength are not constant depending on the site. It has drawbacks.

[0009]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an insert molding method for a transmission member having a high transmission contact surface strength and improved mechanical strength and component reliability.

[0010]

The inventors of the present invention have made extensive studies to achieve the above object, and as a result, the present invention has been achieved.

That is, in the transmission member insert molding method according to the present invention, a spool or a runner having a cold slug well portion at the tip or the end is formed inside, and one or a plurality of gates are covered with resin after molding. Using the insert member formed in the
It is characterized in that the molten resin is fed into the mold through the spool or the runner and the gate of the insert member.

A preferred embodiment of the transmission member insert molding method according to the present invention is to independently mold two or more resin molding parts around the insert member.

[0013]

According to the present invention, the molten resin passes through the spool or runner, which is a hollow portion inside the insert member, and is fed into the mold from the gate, which is a through hole formed in the insert member, A transmission member is obtained. At this time, the cooled resin at the tip of the resin injection nozzle will not be sent into the mold by entering the cold slag well portion formed at the tip or the end of the spool or runner. It does not cause the occurrence of defects such as.

Further, even when there are two or more resin molding parts, there is no need to complicate the passage of the mold spool or runner, or to have two or more resin injection nozzles.
It can be molded extremely easily by one resin injection nozzle.

Further, the obtained transmission member does not have a gate mark on the surface thereof, so that post-processing such as cutting and polishing is unnecessary.

Further, in the obtained transmission member, the resin is integrated in the resin molding portion and the inside of the insert member, so that the positional deviation and the detachment of the insert member can be completely prevented.

[0017]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic sectional view showing a mold with an insert member set, FIG. 2 is a sectional view showing an example of a transmission member obtained by the mold of FIG. 1, and FIG. 3 is a molding method of the present invention. Sectional drawing which shows the other example of the transmission member obtained by
FIG. 4 is a sectional view showing another example of the transmission member obtained by the molding method of the present invention, FIG. 5 is a sectional view showing another example of the transmission member obtained by the molding method of the present invention, and FIG. FIG. 7 is a sectional view showing another example of the transmission member obtained by the molding method, and FIG. 7 is a schematic sectional view showing the transmission member and the mold by the conventional molding method.

In FIG. 1, 1 is two split molds 1A and 1B.
After the insert member 4 having the structure described below is set for each molding, the resin is injected into the cavity 2 of the mold 1 by the resin injection nozzle 3, and as shown in FIG. The transmission member 5 in which the resin molding portion 6 is covered and molded around the insert member 4 is molded. Incidentally, 6A, which is the surface of the resin molding portion 6, is the transmission member 5
And the transmission contact surface 6A means a tooth tip (ti) of the gear when the transmission member 5 is, for example, a gear.
p), the end surface (face), the root surface (flank)
Is to say.

In the present invention, the insert member 4 set in the mold 1 is provided with one or a plurality of through holes 4B in the portion covered by the resin molding portion 6 to serve as a gate for resin injection, and A hollow portion 4A is formed continuously with the through hole portion 4B to serve as a spool or a runner during resin injection.
The position of the through hole portion 4B, which is a gate, may be a portion covered by the resin molding portion 6 after molding, but is preferably substantially the central portion of the resin molding portion 6. Further, the diameter and the number thereof are appropriately determined according to conditions such as the size and material of the insert member 4 used, the type of resin, the required strength of the transmission member 5 to be obtained, and the like, but the plurality of through holes 4B are omitted. It is preferable to provide them radially at equal intervals in terms of uniform molding.
Further, as shown in FIGS. 1 and 2, a cold slag well portion 4C is formed at the tip or end of the spool or runner which is the hollow portion 4A. Due to the presence of the cold slag well portion 4C, when the resin is injected, The cooled resin at the tip of the resin injection nozzle 3 enters the cold slag well portion 4C.

In the insert molding method of the transmission member 5 according to the present invention, the mold 1 as shown in FIG. 1 and the insert member 4 having the above-mentioned structure are used, and the mold is injected from the resin injection nozzle 3 and passed through the mold spool or runner 1C. The resin is passed through the hollow portion 4A formed in the insert member 4 and then injected into the cavity 2 from the through hole portion 4B formed continuously in the hollow portion 4A. That is, the hollow portion 4A formed in the insert member 4 is used as a spool or a runner, and the through hole portion 4B is used as a gate to inject the resin into the cavity 2. At this time, among the injected resins, the cooled resin at the tip of the resin injection nozzle 3 enters the cold slag well portion 4C as described above, and the molten resin continuous to the cooled resin is the cavity of the mold 1. The resin molding portion 6 is formed by being sent into the inside of the resin molding machine 2. Therefore, since the cooled resin is not fed into the cavity 2 of the mold 1, flow marks, short shots, or the like are generated in the resin molding portion 6 to cause a defect or the strength of the transmission contact surface 6A. The resulting transmission member 5 has high strength of the transmission contact surface 6A and improved mechanical strength and reliability of parts.

Further, in the molding method of the present invention, since the position of the gate is substantially the center of the resin molding portion 6 of the transmission member 5 which is an ideal position in injection molding, the injected resin is substantially in the resin molding portion 6. From the center to the outer peripheral surface of the cavity 2, that is,
The resin molding portion 6 has excellent dimensional stability and accuracy because it uniformly flows toward the transmission contact surface 6A as indicated by the arrow X and solidifies. Furthermore, since the gate of the transmission member 5 thus obtained is covered by the resin molding portion 6, no gate marks are left on the surface thereof, so that post-treatment such as cutting and polishing is not necessary, and a change in the finished dimension due to the post-treatment. Therefore, when designing the die 1, the finished dimension of the transmission member 5 can be designed without considering the cutting amount, the polishing amount, and the like. Therefore, by molding with a die having required accuracy, the transmission member 5 with desired finishing accuracy can be obtained.

Further, the transmission member 5 thus obtained has the hollow portion 4 in which the resin is inside the resin molding portion 6 and the insert member 4.
Since it is integrated with A and the through hole portion 4B,
It is possible to completely prevent the positional deviation and the detachment of the insert member 4. Therefore, when the material of the insert member 4 and the type of resin are the same, the mechanical strength of the transmission member 5 obtained by the molding method of the present invention is higher than that of the transmission member obtained by the conventional molding method. High reliability of parts function.
In order to further strengthen the integrity of the resin molded portion 6 and the insert member 4, the through hole portion 4B may be formed in the groove portion 4D formed on the outer periphery of the insert member 4 as shown in FIG.

In the illustrated embodiment, the through holes 4B are arranged radially in one row, but a plurality of rows may be arranged radially or randomly.

Further, in the illustrated embodiment, the resin injection from the resin injection nozzle 3 is injected into the insert member 4 via the mold spool of the mold 1 or the runner 1C. However, the resin injection nozzle 3 may be pressed against the end of the insert member 4 to directly inject the resin.
Furthermore, the injection of the resin is not limited to the end of the insert member 4 on the side closer to the resin molding portion 6, but may be from the end on the far side,
It may be from the surface of the insert member 4 as shown in FIG.

Although one embodiment of the transmission member insert molding method according to the present invention has been described above, according to the molding method of the present invention, the number of resin molding portions 6 of the transmission member 5 to be obtained is not limited to one. It is also applicable to the case of two or more as shown in FIG. That is, even when the number of resin molding portions 6 is two or more by forming the spool or the runner and the gate as shown in FIGS. 4 to 6, the passage of the mold spool or the runner is complicated, or the resin injection nozzle is used. It is possible to mold extremely easily with one resin injection nozzle 3 without having to make two or more.

Although the method for molding the transmission member according to the present invention has been described above, the present invention is not limited to the above, and can be appropriately changed within the scope of the present invention depending on the mode of the transmission member to be molded. Examples of materials used for the insert member 4 and the resin molding portion 6 will be described below.

As the material of the insert member 4 used in the method of the present invention, various known materials as a transmission member by insert molding, that is, metal such as iron, stainless steel, aluminum, brass, or alumina, silicon carbide or the like is used. Ceramics, other heat resistant plastic materials,
Reinforced wood (paper pulp, etc.), bamboo, etc. can be used,
The resin contact surface may be knurled.

The resin to be injected, that is, the material of the resin molding portion 6 may be formed of either a thermoplastic resin or a thermosetting resin. Specifically, as the thermoplastic resin, For example, polyethylene, polypropylene, polymethylpentene, polybutene, polybutadiene, polystyrene, styrene-butadiene resin, polyvinyl chloride,
Polyvinyl acetate, polymethylmethacrylate, polyvinylidene chloride, polytetrafluoroethylene, AS resin,
ABS resin, polyacrylonitrile, polyacetal,
Polyamide, polycarbonate, polyphenylene oxide, polyethylene terephthalate, polybutylene terephthalate, polyarylate, polysulfone, polyphenylene sulfide, polyether sulfone, polyether ether ketone, polyether ketone, polyether imide, polyamide imide, polyimide and the like, also, Examples of the thermosetting resin include formaldehyde resin, phenol resin, amino resin, unsaturated polyester resin, epoxy resin, diallyl phthalate resin, silicone, polyurethane, polyamino bismaleimide resin, and the like, which may be used alone or in combination of two or more. It may be a blend resin.

Further, these resins may be a mixture of fibrous reinforcing materials such as glass fibers, carbon fibers, aramid fibers, ceramics fibers and metal fibers. When the fibrous reinforcing material is mixed, according to the present invention, the fiber orientation is arranged radially in the arrow X direction in FIG. 1, that is, from the substantially central portion of the resin molding portion 6 in the transmission contact surface 6A direction, so that high transmission contact is achieved. Surface strength can be obtained.

[0031]

EFFECTS OF THE INVENTION According to the present invention, since it has the above-mentioned structure, at the time of resin injection, the cooled resin at the tip of the resin injection nozzle enters the cold slag well portion formed at the tip or end of the spool or runner. As a result, the resin is not fed into the mold, so that flow marks, short shots, etc. are not generated in the resin molding part, which does not cause defects, or the strength of the transmission contact surface is not reduced. Therefore, in the obtained transmission member, the strength of the transmission contact surface is high, and the mechanical strength and reliability of parts are improved.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a mold with an insert member set.

FIG. 2 is a sectional view showing an example of a transmission member obtained by the mold of FIG.

FIG. 3 is a cross-sectional view showing another example of the transmission member obtained by the molding method of the present invention.

FIG. 4 is a cross-sectional view showing another example of the transmission member obtained by the molding method of the present invention.

FIG. 5 is a cross-sectional view showing another example of the transmission member obtained by the molding method of the present invention.

FIG. 6 is a cross-sectional view showing another example of the transmission member obtained by the molding method of the present invention.

FIG. 7 is a schematic cross-sectional view showing a transmission member and a mold according to a conventional molding method.

[Explanation of symbols]

1 mold 1A, 1B split type 1C mold spool or runner 2 cavities 3 resin injection nozzle 4 Insert member 4A hollow part (spool or runner) 4B through hole (gate) 4C cold slag well section 4D groove 5 Transmission member 6 Resin molding part 6A Transmission contact surface

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location // B29K 105: 12 105: 20 B29L 31:32 4F (72) Inventor Kazuo Mororo East of Hachioji, Tokyo 55 Asakawacho Koyo Precision Co., Ltd.

Claims (2)

[Claims] 1. An insert member in which a spool or a runner having a cold slug well portion at the tip or the end is formed inside, and one or a plurality of gates are formed in a portion which is covered with resin after molding is used. A method for insert molding a transmission member, characterized in that a resin in a molten state is fed into a mold via a spool or a runner and a gate of the insert member. 2. The transmission member insert molding method according to claim 1, wherein two or more resin molding parts are independently molded around the insert member.