JPH07332438A - Gear device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of pitching during engagement of gears with each other by a method wherein a curing layer is formed on the tooth surface of an involute gear for drive and the curing layer is formed on the tooth surface, except the vicinity of addendum, of the involute gear for drive, and a range not cured is specified. CONSTITUTION:In operation, the addendum of a soft driven gear is easily deformed by a bearing during the starting of contact of a tooth 1, drape occurs at an early stage and thereafter, smooth contact during the starting of contact is practicable. Thus, plastic deformation of the side on which thrust of the addendum is exerted, i.e. the tooth surface of a drive gear, is not progressed. In case of a soft part being 5% or less of a tooth height, during contact, engagement of a hard part is effected, which is not proper. Further, in case of the soft part being 10% or more thereof, durability during ordinary engagement is deteriorated. Therefore, the tooth 6 of the gear comprises a curing layer 2 and a non-curing layer 3 and a range of the non-curing layer 3 not cured is set to 5-10% of a tooth height H. Thus, since friction operation is relaxed, a plastic fluidized bed is difficult to form on a tooth surface and stress operation by which fatigue is caused is prevented from occurring.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gear device including a driving involute gear and a driven involute gear.

[0002]

2. Description of the Related Art For example, as shown in FIG. 9, a gear is provided with hardened layers 20a and 21a on its tooth surface to enhance impact resistance and abrasion resistance. However, the drive gear 2
A so-called pitching phenomenon occurs in which a concave portion is generated near the tooth bottom 20b of the tooth surface of 0. The reason for this is not clear,
When the addendum 21b of the driven gear 21 is engaged, the drive gear 2
It is presumed that the high surface pressure instantaneously generated near the tooth root of 0 repeatedly acts to cause plastic flow on the surface and grow into the recess.

[0003]

[Knowledge] In order to prevent pitching, various experiments have revealed that pitching can be prevented by making the engaging tooth surface of the tooth tip of the driven gear softer than the tooth surface of the driving gear.

[0004]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a gear device which prevents pitching during meshing of gears based on the above findings.

[0005]

According to the present invention, in a gear device comprising a driving involute gear and a driven involute gear, a hardened layer is formed on the tooth surface of the driving involute gear, and the driven involute gear has a hardened layer. A hardened layer is formed on the tooth surface of the involute gear except for the vicinity of the tooth tip, and the range where the hardened layer is not formed is 5 to 10% of the tooth height.
In the present invention, the hardness of the hardened layer is 60 in Rockwell hardness.
The hardness is HRC or more, and the hardness of the portion having no hardened layer is 50 HRC or less in Rockwell hardness.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the practice of the present invention, in order to form a non-hardened layer, a carbon-proof material may be applied thereto, and then the hardened layer may be formed by carburizing and quenching. Alternatively, molten tin may be applied to the non-cured layer and the cured layer may be formed by nitriding treatment. Further, the hardened layer may be formed by carburizing and nitriding treatment, and the non-hardened layer may be formed by induction annealing. Further, the non-hardened layer may be formed by grinding the hardened layer.

[0007]

[Explanation of action and effect] During operation, the tooth tip of the soft driven gear is easily deformed due to the surface pressure at the start of tooth contact, so that familiarity occurs early and after that, smooth contact can be made at the start of contact. become. Therefore, the plastic deformation of the tooth surface of the drive gear, that is, the tooth surface of the driving gear, does not proceed.

A soft portion or less than 5% of the tooth length is not suitable because it engages with a hard portion upon contact. If it is 10% or more, the durability in normal meshing is poor.

[0009]

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

In FIG. 1, the teeth of the gear, generally designated by reference numeral 1, are composed of a hardened layer 2 and a non-hardened layer 3 at the cutting edge, and the range of the non-hardened non-hardened layer 3 is 5-10 of the tooth height H. %It has become. And FIG. 2 which shows the relationship between hardness distribution and hardness
Referring to, the hardened layer 2 has a certain range from the surface (for example,
The range of 0.5 mm) has a Rockwell hardness of 60 HRC or more, and the non-hardened layer 3 has a hardness of 50 HRC or less in the same range.

Therefore, referring to FIG. 3 showing an example of the experimental results, the relationship between the pitching fatigue life and the torque is as follows: the result of the A group without the conventional softening treatment is the result of the B group with the treatment of the present application. On the other hand, the result shows that the number of repetitions is 1/10 or less regardless of the torque value. Referring also to FIG. 8, when the torque is low (T2), pitching does not occur.

FIG. 4 shows an outline of the steps of carburizing the gear to form the non-hardened layer 3 on the hardened layer 2 by carburizing the teeth, and the viscosity is increased on the outer periphery of the rotary drum 5 ( For example, it is configured such that a carbon-repellent material (mixed with a highly thixotropic resin) is applied and the carbon-repellent material adheres to the cutting edge of the gear 6. Then, as shown in FIG.
If it is carburized in a carburizing furnace after being dried at ˜180 ° C., the non-hardened layer 3 is formed on the cutting edge.

FIG. 6 shows a case where the hardened layer 2 and the non-hardened layer 3 are formed by nitriding treatment. Molten tin is put in the plating layer 10 as a nitrogen-proof material, and the rotary drum 12 is dipped in the molten tin to immerse the drum 1 therein.
Molten tin is adhered to the surface of No. 2 and the thickness of the tin is adjusted by blowing air from the airbrush 13 and a gear is pressed against the drum so that tin is adhered to the tooth tips.

Then, if nitriding is performed, the non-hardened layer can be left on the tooth tips. The thickness of the molten tin may be changed within the range of the uncured layer.

FIG. 7 shows a case where a polishing allowance 15 is provided as a portion of the non-hardened layer 3 on the tooth tip, and the polishing allowance is removed by grinding after the carburizing treatment or the nitriding treatment to form the non-hardened layer 3. Therefore, the non-hardened layer of the cutting edge can be configured to obtain the above effects by any method, but which one should be selected depends on the possession situation of the equipment, etc., and there is no difference in effect, and the scope of the present application is not limited. Not bound.

[0016]

Since the present invention is constructed as described above, it has the following excellent effects.

(1) Since the frictional action is alleviated, a plastic fluidized layer is unlikely to be formed on the tooth surface.

(2) The stress action that causes fatigue can be avoided.

(3) Therefore, peeling (pitting) of the tooth surface does not occur.

(4) The durability in normal meshing is improved.

[Brief description of drawings]

FIG. 1 is a sectional view of teeth of a gear according to an embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between the depth from the surface of the hardened layer and the non-hardened layer and the hardness.

FIG. 3 is a diagram showing a relationship between a pitching fatigue life and a driving torque.

FIG. 4 is a diagram showing a coating process of a carbon-proof material.

FIG. 5 is a view showing a drying furnace for the anti-carbon material.

FIG. 6 is a schematic diagram of a molten tin coating device.

FIG. 7 is a view showing a grinding allowance for grinding an uncured layer.

FIG. 8 is a diagram showing an experimental example of the relationship between the number of repetitions and torque.

FIG. 9 is a view showing a state in which the teeth of the non-driving gear are thrust into the driving gear.

[Explanation of symbols]

 1 ... Gear tooth 2 ... Hardened layer 3 ... Non-hardened layer 6 ... Gear 7 ... Oven furnace 10 ... Plating layer 11 ... Molten tin 15 ... Grinding allowance

Claims (6)

[Claims] 1. In a gear device comprising a driving involute gear and a driven involute gear, a hardened layer is formed on the tooth surface of the driving involute gear, and the tooth surface of the driven involute gear is near the tooth tips. The gear device is characterized in that a hardened layer is formed except for, and the range where the hardened layer is not formed is 5 to 10% of the tooth height. 2. The hardness of the hardened layer is 60 as Rockwell hardness.
The gear device according to claim 1, which has a hardness of HRC or more and a hardness of a portion without a hardened layer is 50 HRC or less in Rockwell hardness. 3. The gear device according to claim 1, wherein the non-hardened layer is coated with a carburizing agent, and the hardened layer is formed by carburizing and quenching. 4. The gear device according to claim 1, wherein molten tin is applied to the non-hardened layer, and the hardened layer is formed by a nitriding treatment. 5. The gear device according to claim 1, wherein the hardened layer is formed by carburizing quenching or nitriding treatment, and the non-hardened layer is formed by induction annealing. 6. The gear device according to claim 1, wherein the non-hardened layer is formed by grinding the hardened layer.