JPH04193511A - Manufacture of gear by injection molding - Google Patents

Abstract

PURPOSE:To realize high strength and upgrade resistance to wear, low noise properties and mass production properties of highly loaded sections by injection molding a main section and a tooth base sections of a gear by means of high strength resin, and then injection molding tooth profile sections on the outside of a tooth base section with its main body as a core by means of resin of low coefficient of friction or low noise properties. CONSTITUTION:A gear 1 is composed of a gear main body 4 forming tooth base sections 3 in equal pitch on the outer peripheral side of a gear main section 2 by injection molding resin of high strength and a tooth profile section 5 formed by injection molding resin of resistance to wear or low noise properties in the given thickness on the outer faces of the tooth base sections 3. When the gear main section 2 and the tooth base sections 3 of the gear are composed of high strength resin, the gear main section 2 of the gear can be fixed firmly to a shaft, and heat developing properties are smaller by composing the tooth profile sections 5 to lower the friction of opposite gear remarkably. Also, when the tooth profile section 5 is composed of resin of low noise, the generation of noise is controlled.

Description

[Detailed description of the invention] Two industrial fields of application] The present invention relates to a method for manufacturing gears by injection molding.

[Conventional technology] In recent years, metal sliding parts have been replaced with resins such as engineering plastics in an effort to reduce weight and improve mass productivity.However, many resin sliding parts are made of - Therefore, the characteristic function as a sliding part must depend on its material.

! [Problems to be Solved by the Invention] However, when a resin sliding part is constructed of one type of material, if the resin sliding part is required to have two distinctive functions that are significantly different from each other, it is necessary to There is a problem of not being able to do the same thing.

For example, the main part of a gear needs to be firmly fixed to the shaft, and for this reason the entire gear needs to be made only of high-strength resin, or high-strength resin is highly abrasive and generates heat, and it also causes significant wear on the other party. This may cause problems such as excessive noise or abnormally high noise levels.

An object of the present invention is to provide a novel method for manufacturing gears in which the gears are made of resin materials having different physical properties.

[Means for Solving 3 Problems] In order to achieve the above object, the present invention injection molds the main part and tooth base part of a gear with a high-strength resin, and then injects the above-mentioned parts with a low friction coefficient or low noise resin. The tooth profile portion is injection molded on the outside of the tooth base portion using the main body as a core.

■If the main part of the gear and the tooth base of the two-gear are made of high-strength resin, the main part of the gear can be firmly fixed to the shaft.
Furthermore, if the tooth profile is made of a resin with a low coefficient of friction, the heat generation will be reduced, and the wear of the mating part will be significantly reduced.

In addition, when the tooth section is made of a resin that produces noise, the generation of noise can be suppressed.

[Embodiment] A preferred embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a plan view of a plastic gear formed using the method for manufacturing gears by injection molding according to the present invention. The gear 1 includes a gear main body 4 made of high-strength resin injection molded, and a tooth base portion 3 formed on the outer circumferential side of the gear main portion 2 with equal pinching, and a gear body 4 having a wear-resistant or low-wearing tooth base portion 3 on the outer surface of the tooth base portion 3. It consists of a toothed part 5 molded by injecting a noisy resin to a predetermined thickness. The gear body 4 has a shaft 6 at its axial center.
It is provided with a shaft fitting hole 7 for integrally fitting.

Examples of high-strength resins include engineering plastics such as PBT (polybutylene lentiflate), PA (polyamide), POM (polyacetal), LCP (liquid crystal polymer), PES (bolyether sulfone), and PP5 (polyphenylene sulfide). is used. By incorporating carbon fibers, inorganic substances, etc. into these resins, the strength can be further increased.

ROM (polyacetal) is a wear-resistant resin.
A resin having lubricating properties such as PPS or PPS (polyphenylene sulfide) is used. In such resin, P
By including TFE (polytetrafluoroethylene) powder, molybdenum disulfide, solid lubricant, oil, etc., the thermal lubricity of the layer can be improved. In addition, low-noise resins include, for example, styrene-based, olefin-based, urethane-based,
Ester-based, amide-based, and fluorine-based thermoplastic elastomers are used.

Specific Example (1) The gear body 4 was first injection molded using PA (polyamide) containing 40 wt% of glass fiber, and then PTFE (polytetrafluoroethylene) was molded on the outside of the gear body 4.
Secondary injection molding of the tooth profile portion 5 was performed using ROM (polyacetal) containing 10 wt% of the following.

Specific Example (2) The gear body 4 was formed by performing primary injection molding with ROM <polyacetal> to which 30 wt% of glass fiber was added, and then Bandex T, which is a urethane-based thermoplastic, was formed.
The gear 1 was injection molded by injection molding the toothed portion 5 on the outside of the gear body 4 using (commercial li).

In this way, if the gear main part 2 and the tooth base part 3 of the gear 1 are made of high-strength resin, the gear main part 2 of the gear 1 can be firmly fixed to the shaft 6, and the tooth profile part 5 can be made of a resin with a low coefficient of friction. With this structure, the heat generation is reduced, and the wear of the other side is significantly reduced. Furthermore, when the toothed portion 5 is made of a low-noise resin, the generation of noise is suppressed.

Glass fibers further increase the strength of high strength resins.

[Effects of the Invention] As is clear from the above explanation, the present invention exhibits the following excellent effects.

(1) It is possible to provide a resin gear that is reinforced in areas that require high strength, wear resistance, or low noise in areas where high loads are applied.

(2) There is no unreasonable moldability, and mass productivity can be greatly improved.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a gear according to the present invention. In the figure, 1 is a gear, 2 is the main part of the gear, 3 is the tooth base, and 5
is the tooth profile.

Claims (1)

[Claims] 1. The main part of the gear and the tooth base are injection molded with high-strength resin, and then the tooth profile is injection molded on the outside of the tooth base with the main body as a core using a low friction coefficient or low noise resin. A unique method for manufacturing gears using injection molding.