JPH09324257A - Method for carburizing member having tooth shape on inner curcumferential face, and work holding mechanism used for the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form hardened layers with different depth respectively on the outer curcumferential face and inner curcumferential face with a tooth shape of a work by a simple method and to improve the production efficiency. SOLUTION: Inner races 22 are put through a supporting axial member 16, an annular gap 20 with prescribed distance (A-B) is formed between a tooth- shaped member 26 formed on the inner curcumferential face of the inner race 22 and the outer circumferential face of the supporting shaft member 16, and, while the state in which the plural inner races 22 are successively laminated along the axial direction of the supporting axial member 16 is held, the inner races 22 are subjected to carburizing treatment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carburizing method for a member having a tooth profile on its inner peripheral surface and a work holding used in the carburizing method for carburizing a member having a tooth profile on its inner peripheral surface. Regarding the mechanism.

[0002]

2. Description of the Related Art Conventionally, there has been known a carburizing method of hardening carbon by diffusing carbon into the surface layer of a metal member and carrying out quenching treatment.

For example, when the carburizing method is used for a part having serrations formed on the inner peripheral surface thereof, such as an inner race constituting a Barfield type constant velocity universal joint, the outer peripheral surface and the inner peripheral surface of the inner race are used. Since the hardened layer is formed with a uniform depth on the entire surface including the surface, cracks may occur in the serrated portion of the inner peripheral surface when a force is applied during use. This is because a hardened layer is formed more than necessary on the inner peripheral surface of the inner race. The same applies to the spider forming the tripod type constant velocity universal joint in that the cracks are generated.

In order to prevent the generation of the cracks, a carburization preventing agent (for example, nickel plating) is applied to the serration portion, or the serration portion is hardened to prevent the surface of the serration portion from being hardened. A method is used in which is surrounded by a flat spacer, a charcoal-proof plate, or the like.

[0005]

However, in the former method using a carburizing inhibitor, it is necessary to remove the carburizing inhibitor from the inner race after the carburizing and quenching treatment, and it is complicated. There is a disadvantage that the depth of the hardened layer with respect to the surface layer portion of the inner race cannot be adjusted.

Further, in the latter method using a flat spacer, a carbon plate, etc., since the work of installing the flat spacer has to be done manually, a great deal of labor and time are required and the production efficiency is lowered. There is.

The present invention has been made to overcome the above-mentioned various inconveniences, and a hardened layer having different depths on the outer peripheral surface of a work and the inner peripheral surface having a tooth profile by a simple method. It is an object of the present invention to provide a carburizing method for a member having a toothed shape on the inner peripheral surface capable of improving the production efficiency and a work holding mechanism used in the carburizing method.

[0008]

In order to achieve the above-mentioned object, the present invention inserts a work into a shaft member standing on a base through a hole in an inner peripheral surface, An annular gap having a predetermined spacing is formed between the tooth-shaped portion formed on the peripheral surface and the outer peripheral surface of the shaft member, and a plurality of works are sequentially laminated along the axial direction of the shaft member. ,
The process of communicating the annular gap formed by each work along the axial direction of the shaft member, and the loading of multiple stacked works into the heat treatment furnace while maintaining the communication of the annular gap with a predetermined spacing A step of forming a hardened layer shallower than the outer peripheral surface on the inner circumference of the work by heating the plurality of works to a predetermined temperature and supplying a carburizing agent into the heat treatment furnace to perform the carburizing treatment. And are included.

Further, the present invention is a mechanism for holding a plurality of works when the plurality of works carried into the heat treatment furnace are heated to a predetermined temperature and a carburizing agent is supplied to carry out the carburizing treatment. A frame that is disposed on the upper surface of the base and is spaced apart from the base by a predetermined distance so as to be substantially parallel or intersect with each other in a direction substantially orthogonal to each other, and to support a workpiece, and in a direction substantially orthogonal to the base. A toothed portion formed on the inner peripheral surface of the work, the shaft member being provided upright and having a plurality of works stacked in the axial direction through a hole formed on the inner peripheral surface of the work. And an outer peripheral surface of the shaft member, an annular gap having a predetermined spacing is provided along the axial direction of the shaft member.

According to the present invention, first, a plurality of works are sequentially stacked along the axial direction of the shaft member constituting the work holding mechanism, and the annular gap formed by the respective works is set along the axial direction of the shaft member. To communicate. That is, the work is inserted through the shaft member provided upright on the base through the hole of the inner peripheral surface, and between the tooth-shaped portion formed on the inner peripheral surface of the work and the outer peripheral surface of the shaft member. An annular gap having a predetermined spacing is formed.

Next, a plurality of stacked works are loaded into the heat treatment furnace while maintaining the communication of the annular gaps having a predetermined spacing, and the plurality of works are heated to a predetermined temperature, and the heat treatment furnace is heated. The carburizing agent is supplied to the inside of the carburizing process.

The outer peripheral surface of the work is carburized by the carburizing agent supplied into the heat treatment furnace, and the inner peripheral surface having the tooth profile is carburized by the carburizing agent flowing along the annular gap. It In this case, since the flow rate of the carburizing agent flowing through the inner peripheral surface of the work is limited by the annular gap, a hardened layer shallower than the outer peripheral surface is formed on the inner peripheral surface of the work.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Regarding the carburizing method for a member having a tooth profile on the inner peripheral surface according to the present invention, preferred embodiments will be given in relation to a heat treatment apparatus for carrying out the same, with reference to the accompanying drawings. The details will be described below.

This heat treatment apparatus includes a holding mechanism (work holding mechanism) 10 for holding a plurality of works in a vertically stacked state (see FIG. 1A). The holding mechanism 10
It has a plurality of frame bodies 14 arranged side by side substantially in parallel, and a plurality of support shaft members (shaft members) 16 that are spaced apart by a predetermined distance along the longitudinal direction of the frame body 14. The support shaft member 16 is made of a pipe having a through hole 18 formed along the axial direction, and is fixed between a pair of adjacent frame bodies 14 by a method such as welding (see FIG. 1B). . Further, as shown in FIG. 2A, the diameter of the support shaft member 16 is formed to have a predetermined length so as to secure an annular gap 20 having a predetermined distance from the inner peripheral surface of the work. In this case, the spacing is the difference (AB) between the inner diameter A of the inner race 22 and the outer diameter B of the support shaft member 16.

As the work to be carburized, an inner race 22 which constitutes a Barfield type constant velocity universal joint is used. This inner race 22
Is manufactured in advance by, for example, a cold forging device (not shown) and has a through hole having a predetermined diameter along the axial direction. On the outer peripheral surface of the inner race 22,
As shown in FIG. 2B, a plurality of semicircular groove portions 24 that substantially function as ball rolling grooves are formed at predetermined intervals along the circumferential direction, and the inner peripheral surface of the through hole is A tooth-shaped portion (serration) 26 for fitting the drive shaft is formed.

The heat treatment apparatus for carrying out the carburizing method according to this embodiment is basically constructed as described above. Next, its function and effect will be explained.

First, the inner race 22 is inserted through the through hole along the axial direction of the support shaft member 16, and a plurality of inner races 22 are sequentially laminated along the support shaft member 16.
The plurality of laminated inner races 22 are supported on a pair of frame bodies 14 that are adjacent to each other substantially in parallel (see FIGS. 2A and 2B).

Further, between the tooth-shaped portion 26 formed on the inner peripheral surface of the inner race 22 and the outer peripheral surface of the support shaft member 16, there is a substantially uniform and predetermined separation distance along the circumferential direction. An annular gap 20 having is formed. As shown in FIG. 2A, the one end portion 20a of the annular gap 20 formed so as to communicate with each other along the axial direction of the support shaft member 16 is in a communication state with the outside without being blocked, and the support shaft member 16 is also provided. Similarly, the other end 20b of the annular gap 20 formed on the lower side of the concave portion 2 is formed by the frame body 14 without being blocked.
It is in communication with the outside through 8.

A plurality of inner races 22 are laminated while maintaining a state in which the tooth-shaped portion 26 formed on the inner peripheral surface of the inner race 22 and the outer peripheral surface of the support shaft member 16 are separated from each other by a predetermined distance. The holding mechanism 10 is carried into a chamber of a heat treatment furnace (not shown), and the inner race 22 is carburized.

That is, in the closed chamber of the heat treatment furnace,
A gas (for example, methane gas, propane gas, etc.) as a carburizing agent is supplied through a gas supply means (not shown), and the inner race 22 is supplied through a heating means (not shown).
Is heated to a predetermined temperature. In this case, the carbon component in the gas supplied into the chamber of the heat treatment furnace is absorbed by the outer peripheral surface of the inner race 22, so that a hardened layer having a predetermined depth is formed on the surface layer portion of the outer peripheral surface.

On the other hand, since the tooth-shaped portion 26 formed on the inner peripheral surface of the inner race 22 faces the outer peripheral surface of the support shaft member 16 via the annular gap 20 having a predetermined spacing, the annular shape is formed. The flow rate of the gas circulating along the gap 20 is limited. Therefore, as compared with the outer peripheral surface of the inner race 22, the amount of carbon component in the gas absorbed by the tooth-shaped portion 26 formed on the inner peripheral surface of the inner race 22 is limited. A hardened layer shallower than the outer peripheral surface is formed on the tooth-shaped portion 26.

FIG. 12 shows a Vickers hardness curve when the inner race 22 is carburized by using the holding mechanism 10 shown in FIG. 1A. In this case, the outer peripheral surface of the support shaft member 16 and the tooth-shaped portion 26 (inner peripheral surface) of the inner race 22.
The Vickers hardness was measured by setting the separation distance (A-B) from and to 0.5 (mm). In FIG. 12, a curve C shows the Vickers hardness of the outer peripheral surface, and a curve D shows the Vickers hardness of the tooth profile 26. The depth of the outer peripheral surface refers to the depth from the outer peripheral surface of the inner race 22 toward the center, and the depth of the tooth profile portion 26 is the depth of the tooth profile portion 26.
To the depth outward from the radius.

As can be seen from FIG. 12, the hardened layer is formed deeply on the outer peripheral surface of the inner race 22, and the hardened layer is formed shallowly on the tooth profile 26 on the inner peripheral surface of the inner race 22. It is understood that the outer peripheral surface and the tooth profile 26 have different hardness.

Next, the holding mechanism 10 which constitutes the heat treatment apparatus.
Modifications of the above are shown in FIGS. 3A, 3B, 4A and 4B. It should be noted that in the modified example of the holding mechanism shown below,
The same components as those of the holding mechanism 10 shown in A are designated by the same reference numerals, and detailed description thereof will be omitted.

The holding mechanism 34 is preferably used when carburizing the spider which constitutes a tripod type constant velocity universal joint. As shown in FIG. 4B, the spider 30 has 12
A spider shaft 32 is fixed at intervals of 0 degree, and a tooth profile portion (serration) 26 is formed on the inner peripheral surface penetrating the spider shaft 32, similar to the inner race 22.

As shown in FIGS. 3A and 3B, frame members 36 are assembled to the holding mechanism 34 so as to intersect each other at substantially right angles, and the support shaft member 16 is provided at the intersection of the frame members 36. It is erected. Note that the other operation effects are the same as those of the holding mechanism 10 shown in FIG. 1A, and thus detailed description thereof will be omitted.

Next, holding mechanisms 38 and 4 according to another modification.
0 is shown in FIGS. 5 shows the case where the work is the inner race 22 and FIG. 6 shows the case where the work is the spider 30, and the carburizing method is the same. Therefore, they will be described below simultaneously.

In the holding mechanism 38 (40), a rod member 42 (44) having a predetermined diameter is used instead of the support shaft member 16 having a through hole 18 formed along the axial direction. ) Is different in that it is erected against. In the rod member 42 (44), a pair of clearance adjusting members 46a is provided through a circular hole formed on the inner peripheral surface,
46b (48a, 48b) is detachably inserted. The rod member 42 (44) has a holding mechanism 38 (4
0) by repeatedly using the rod member 42
It is possible to prevent warpage that occurs in (44) and improve durability.

This pair of clearance adjusting members 46a,
46b (48a, 48b) is, for example, the rod member 42.
The clearance adjusting members 46a and 46b (48a, 4a, 4b) are formed by ring-shaped washers surrounding the outer peripheral surface of (44).
A predetermined annular gap 50 is formed between the inner peripheral surface of 8b) and the outer peripheral surface of the rod member 42 (44). The pair of clearance adjusting members 46a, 46b (48a, 48b)
Is the inner race 22 (Spider 3
0) and the clearance adjusting member 46
The annular gap 50 of a, 46b (48a, 48b) communicates with the annular gap 20 of the inner race 22 (spider 30). Therefore, the pair of clearance adjusting members 46a, 46
b (48a, 48b) is adjusted by adjusting the separation distance (AB) of the annular gap 50 communicating with the annular gap 20 of the inner race 22 (spider 30).
Performs the function of adjusting the flow rate of gas that enters inside.

In this case, various types of clearance adjusting members 46a, 46b having different diameters of the holes on the inner peripheral surface are provided.
(48a, 48b) are prepared in advance, and the operator sets a desired spacing (A-) with respect to the outer peripheral surface of the rod member 42 (44).
B) having clearance adjusting members 46a, 46b (4
8a, 48b) can be selected.

Here, the process of carburizing the spider 30 will be briefly described with reference to FIG.

In a heat treatment furnace (not shown), the spider 30 is heated to a predetermined temperature through a heating means (not shown), and a gas supply means (not shown) is energized to enter the heat treatment furnace. Gas is supplied (heating process). A carburization process is performed while maintaining the heating state for the spider 30, and a diffusion process and a soaking process are sequentially performed, and then the spider 30 is cooled to a predetermined temperature by a quenching oil tank (not shown), thereby carburizing. The process ends.

Next, in the spider 30 which has been carburized through the above steps, when the spacing (AB) set by the clearance adjusting members 46a and 46b (48a and 48b) is changed. The relationship with the hardened layer in FIG. In FIG. 8, the alternate long and short dash line indicates the hardened layer formed on the outer peripheral surface of the spider 30,
The solid line indicates the hardened layer formed on the tooth-shaped portion 26 on the inner peripheral surface of the spider 30. In this case, only the diameter A of the inner peripheral surfaces of the clearance adjusting members 46a and 46b (48a and 48b) is changed, and the other conditions are the same.

As can be seen from FIG. 8, the rod member 4
When the distance (A-B) between the outer peripheral surface of No. 4 and the inner peripheral surfaces of the clearance adjusting members 48a and 48b is gradually increased,
The depth of the hardened layer formed on the outer peripheral surface of the spider 30 is constant at about 1.0 mm, while the depth of the hardened layer formed on the tooth-shaped portion 26 on the inner peripheral surface is 2.0 mm. It increases proportionally until it exceeds. In this case, the separation distance (A-B)
Is increased, the flow rate of the gas flowing into the annular gap 20 is increased, and the hardened layer formed on the tooth profile 26 can reach a predetermined depth.

Next, a modified example of the holding mechanisms 50 and 52 is shown in FIG.
11 to FIG.

In the holding mechanisms 50 and 52, instead of the rod members 42 and 44 shown in FIGS. 5 and 6, a through hole 54 is formed along the axial direction, and the outer peripheral surface communicates with the through hole 54. Is provided with a support shaft member 58 having a plurality of holes 56 formed therein, and a pair of closing members 60a are fitted to one end and the other end of the support shaft member 58 to close the annular gap 20. , 60b are provided. The hole 56 may be either a circular hole 56 (see FIGS. 9 and 10) or an elongated hole 62 (see FIG. 11) substantially parallel to the axis of the support shaft member 58.

The gas supplied through the through hole 54 passes through a plurality of holes 56 (or elongated holes 62) and is introduced into the annular gap 20 which is continuous along the axial direction of the support shaft member 58. It is absorbed by the tooth-shaped portion 26 formed on the inner peripheral surface of the inner race 22 (spider 30). in this way,
The flow rate of the gas supplied to the tooth-shaped portion 26 is set to the spindle member 5
This can be controlled by the plurality of holes 56 (or the elongated holes 62) formed in the No. 8 structure.

In the present embodiment, the inner race 22 and the spider 30 are used as the work, but the present invention is not limited to this, and all members having a tooth profile on the inner peripheral surface of the work. Of course, it can be applied to.

[0039]

According to the present invention, the following effects can be obtained.

That is, by using the work holding mechanism having a simple structure, it is possible to form hardened layers having different depths on the outer peripheral surface of the work and the inner peripheral surface having the tooth profile.

Further, by adjusting the spacing between the annular gaps, the depth of the hardened layer obtained by the carburizing process can be freely adjusted.

Further, since the carburizing process can be efficiently performed on a plurality of works by a simple method of using the work holding mechanism, the production efficiency can be improved.

[Brief description of drawings]

1A is a perspective view of a holding mechanism of a heat treatment apparatus for carrying out a method for carburizing a member having a tooth profile on an inner peripheral surface according to the present invention, and FIG. 1B is a partial plan view of FIG. 1A.

2A is a vertical cross-sectional view of a state in which works are stacked by the holding mechanism shown in FIG. 1, and FIG. 2B is a plan view of FIG. 2A.

3A is a perspective view showing a modified example of the holding mechanism, and FIG. 3B is a partial plan view of FIG. 3A.

4A is a vertical cross-sectional view of a state in which works are stacked by the holding mechanism shown in FIG. 3, and FIG. 4B is a plan view of the state.

FIG. 5 is a vertical cross-sectional view showing another modified example of the holding mechanism.

FIG. 6 is a vertical cross-sectional view showing another modified example of the holding mechanism.

FIG. 7 is a schematic process diagram showing each process of the carburizing method.

FIG. 8 is an explanatory diagram showing the relationship between the spacing and the hardened layer that control the flow rate of gas.

FIG. 9 is a vertical cross-sectional view showing another modified example of the holding mechanism.

FIG. 10 is a vertical cross-sectional view showing another modified example of the holding mechanism.

FIG. 11 is a partial cross-sectional view showing another modified example of the holding mechanism.

FIG. 12 is an explanatory diagram showing the hardness of the outer peripheral surface and the inner peripheral surface of the work carburized.

[Explanation of symbols]

10, 34, 38, 40, 50, 52 ... Holding mechanism 14, 36 ... Frame body 16, 58 ... Support shaft member 18, 54 ... Through hole 20, 50 ... Annular gap 22 ... Inner race 26 ... Tooth profile portion 30 ... Spider 42, 44 ... Rod member 46a, 46b, 48a, 48b ... Clearance adjusting member 60a, 60b ... Closing member

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shoji Yano 19 Matsuyama-cho, Moka-shi, Tochigi Prefecture Honda Motor Co., Ltd. Tochigi Works (72) Inventor Takashi Ichimura 19 Matsuyama-machi, Moka-shi, Tochigi Honda Motor Co., Ltd. Tochigi Inside the factory

Claims (4)

[Claims] 1. A tooth-shaped portion formed on the inner peripheral surface of the work and an outer peripheral surface of the shaft member by inserting a work into a shaft member that is erected on a base through a hole in the inner peripheral surface. An annular gap having a predetermined spacing is formed between the plurality of works, and a plurality of works are sequentially stacked along the axial direction of the shaft member, so that the annular gap formed by each work is set in the axial direction of the shaft member. And a plurality of works stacked in a heat treatment furnace while maintaining a communication state of an annular gap having a predetermined separation distance, and heating the plurality of works to a predetermined temperature, and performing the heat treatment. By supplying a carburizing agent into the furnace and performing carburizing treatment, a step of forming a hardened layer that is shallower than the outer peripheral surface on the inner periphery of the work is included, and the tooth profile is formed on the inner peripheral surface. A method of carburizing a member having. 2. A mechanism for holding a plurality of works when heating a plurality of works carried into a heat treatment furnace to a predetermined temperature and supplying a carburizing agent to carry out carburizing treatment, the base comprising: A frame body that is disposed on the upper surface of the base and is substantially parallel to each other and intersects in a direction substantially orthogonal to each other at a predetermined distance, and stands upright in a direction substantially orthogonal to the base, A shaft member in which a plurality of works are stacked along the axial direction through a hole formed in the inner peripheral surface of the work, and the tooth profile portion and the shaft member formed in the inner peripheral surface of the work. A work holding mechanism, wherein an annular gap having a predetermined gap is provided between the outer peripheral surface and the outer peripheral surface along the axial direction of the shaft member. 3. The work holding mechanism according to claim 2, further comprising a clearance adjusting member for setting the spacing of the annular gap to a predetermined value. 4. The mechanism according to claim 2 or 3, wherein a set of closing members for closing the annular gap is provided, and a plurality of holes or grooves communicating with a through hole penetrating along the axial direction of the shaft member. Is provided on the outer peripheral surface of the shaft member.