JPH05172212A - Molded gear - Google Patents

Abstract

PURPOSE:To retain a high tooth strength even at high temps. and under high loads which have been weak points for conventional gears and reduce abrasion on the gear surface even under the lubrication by a lube oil such as grease which sustaining characteristics of the resin made gear of the prior art, e.g. light weight, self-lubrication, corrosion resistance, low noise and mass productivity. CONSTITUTION:A molded gear is formed from a resin compound consisting of 60-90% thermoplastic polyether aromatic ketone and 10-40wt.% pitch basis carbon fiber having a tensile modulus of elasticity between 220-260 GPa and a tensile strength of 2000-4000MPa.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin gear, which is used in the field of automobile equipment parts, electronics, electric equipment, and other general industrial equipment. In particular, the root strength and wear resistance of the tooth meshing surface are high. The invention relates to a resin gear having both high properties.

[0002]

2. Description of the Related Art Conventionally, resin gears used for the above-mentioned applications are lightweight, self-lubricating, corrosion resistant, low noise,
Since it has many features such as mass productivity, it is widely used in various fields. However, resin gears generally have lower mechanical strength than metal gears, and have drawbacks in terms of wear resistance and heat resistance, and have drawbacks in terms of higher strength and wider operating temperature range. ..

In consideration of these points, conventionally, as a resin gear, a polyamide resin, a polyacetal resin, or a gear in which a fibrous reinforcing material such as glass fiber or carbon fiber is mixed with these resins is heavily used. Has been done. Further, in recent years, heat resistant resins such as polyarylene sulfide resin reinforced with glass fiber or carbon fiber, polyether ether ketone resin, polyimide resin and the like have been used for high temperature and high load applications. ..

However, even in these improved resin gears, the root strength is still not sufficient, and particularly in the case of resin gears reinforced with glass fiber or carbon fiber, the purpose is to improve the load characteristics. When it is used under grease lubrication, there is a problem that the wear of the tooth meshing surface is increased and the life of the gear is shortened.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned drawbacks of conventional resin gears and provides a gear suitable for high temperature and high load applications and having excellent wear resistance. It was studied for the purpose.

[0006]

According to the present invention, according to the above-mentioned object, a conventional resin gear is used by using a polyether aromatic ketone resin as a basic resin and combining pitch-based high strength carbon fibers as a reinforcing material. It was found that a resin gear having high tooth root strength even at high temperature and less wear on the tooth surface even when a grease-like lubricating oil is used can be obtained by solving the above-mentioned drawbacks. It was completed.

That is, according to the present invention, the thermoplastic polyether aromatic ketone resin is 60 to 90 wt% and the tensile elastic modulus is 220.
A gear molded product obtained by molding a resin composition comprising 10 to 40 wt% of pitch-based carbon fiber having a tensile strength of 2,000 to 4000 MPa and a tensile strength of 2,000 to 4,000 MPa.

The above-mentioned thermoplastic polyether aromatic ketone resin is, for example, VICTREX PEEK manufactured by ICI.
The pitch-based carbon fiber is a high-strength type carbon fiber whose precursor is anisotropic pitch and has a tensile elastic modulus of 220 to 260 GPa and a tensile strength of 2000 to 4
Those having a pressure of 000 MPa include, for example, diary of Mitsubishi Kasei Co., Ltd., Granock of Nippon Oil Co.

Further, regarding the blending ratio of the carbon fibers, the higher the blending amount of fibers, the higher the strength, but on the other hand, in consideration of the fact that the resin has a high melt viscosity at the time of injection molding and is difficult to mold, A practical limit is 10 to 40 wt%, preferably 20 to 30 wt%.

[0010]

EXAMPLES The constitutions and specific effects of the present invention will be specifically described below based on Examples.

Example 1 Thermoplastic Polyether Aromatic Ketone (VICTREXPEEK 450 manufactured by ICI)
G) 75 parts by weight of pitch-based carbon fiber [Mitsubishi Kasei's diary short fiber (tensile modulus 220 GPa, tensile strength 2
350 MPa, fiber diameter 10 μm, fiber length 6 mm)] 25
Parts by weight were mixed by a mixer and kneaded into pellets by a screw type extruder.

Comparative Example-1 Instead of the pitch-based carbon fiber in Example-1, a PAN-based carbon fiber having approximately the same tensile elastic modulus and tensile strength [Vesphite HTA short fiber manufactured by Toho Rayon Co., Ltd. (tensile elastic modulus 235 GPa, tensile strength 3
630 MPa, fiber diameter 7 μm, fiber length 6 mm)] and pelletized in the same manner.

Comparative Example-2 For comparison with other resins, the following two types of molding material compositions were obtained and comparative tests were conducted. TPI --- Carbon fiber 30 wt%, reinforced thermoplastic polyimide resin (NEW-TPI, JCN3 manufactured by Mitsui Toatsu Chemicals, Inc.)
030) POM-polyacetal resin (DURACON M90 manufactured by Polyplastics Co., Ltd.)

Gears were molded by injection molding using these pellets, and the load characteristics and tooth surface wear height of the gears were measured using the power absorption type gear dynamic tester shown in FIG. Shown in. The gear is an involute spur gear, and the specifications are: pitch circle diameter 30 mm, module 1.0, number of teeth 30, pressure angle 20 °, tooth width 8 mm, mounting boss inner diameter 20 mm, JIS B1701 It is a standard gear designed according to.

Lubrication for (1) in Table 1 shows the case of 0.5 cc of lithium grease and initial coating. (2) shows the amount of wear when the load torque is 20 kgf · cm and the cumulative rotation speed is 3 × 10 ⁶ times. (3) shows the load torque at the time of breaking at the cumulative rotation speed of 1 × 10 ⁷ .

As shown in the above test results, the gear molded product according to the present invention has significantly higher load characteristics than other resin gears and is used under grease lubrication. In this case, it was clearly recognized that the wear resistance was significantly improved and the load characteristics were further improved, as compared with the conventional PAN-based carbon fiber reinforced thermoplastic polyether aromatic ketone resin.

[0017]

As described above, the gear molded article according to the present invention has extremely high tooth root strength and wear resistance as compared with the conventional resin gear, especially when the grease is initially applied. The maximum allowable maximum load torque is large, and it is possible to operate in a high load range in both lubrication and grease lubrication. Combined with the features of mass productivity, light weight, corrosion resistance, low noise, and self-lubricating property of gears, they are of great industrial utility value.

[Brief description of drawings]

FIG. 1 is a simplified diagram of a gear dynamic tester for measuring the load capacity of a gear.

[Table 1]

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Claims (1)

[Claims] 1. A thermoplastic polyether aromatic ketone 60.
A gear molded article characterized by molding a resin composition consisting of 10 to 40 wt% of pitch-based carbon fibers having a tensile modulus of elasticity of 220 to 260 GPa and a tensile strength of 2000 to 4000 MPa.