JPH05223117A - Counter shaft and manufacture thereof - Google Patents

Abstract

PURPOSE:To reduce weight and manufacturing cost by making a shaft internal part hollow from the jointed end parts of two shafts to respective distances in the axial direction, machining the jointed end parts into an approximately identical shape, and jointing both the jointed end parts by means of friction pressure welding. CONSTITUTION:The counter shaft is provided with a hollow part 1a at a shaft central pat, and obtained by separately forging a shaft material 1 where notched parts 2a are provided on both the sides of a rib part 2 where a gear is machined and a shaft material 3 where a hollow part 3a is provided at the shaft central part by using respective dies. The joint end part 1b of the shaft material 1 and the joint end 3b of the shaft material 3 are made to face each other, and external force is applied in an arrowed direction for pressure-welding, and the shaft materials 1, 3 are rotated relatively to generate frictional heat at a contact surface, and larger force is applied when the heat satisfies a prescribed condition for pressure-welding. After jointing, necessary machining is carried out, and carburization hardening is carried out to heighten mechanical strength of the joint part 4. It is possible to provide a hollow part, and notch the rib part by means of vertical notching of forging, thus providing reduction in weight and manufacturing cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention finds use in a counter shaft for an automobile transmission. In particular, it relates to weight reduction of the counter shaft.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 3, a material for a counter shaft of this type has been "forged" into a unitary structure by a horizontal casting method.

[0003]

In such a conventional counter shaft material, since the shaft portion is "pulled", the weight is heavy, and since the material is large, forging must be performed by a horizontal striking method. However, in the case of this horizontal striking method, the rib portion to be gear-processed has extra meat, which further increases the weight.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a counter shaft which can be reduced in weight and can be manufactured at a low cost, and a manufacturing method thereof.

[0005]

SUMMARY OF THE INVENTION The present invention is a method for manufacturing a single counter shaft by separately manufacturing two shafts by forging and joining the two shafts with their shaft centers aligned with each other. In the above, the two shafts are hollow inside from their joint ends to respective distances in the axial direction, and the joint ends of the two shafts are machined into substantially the same shape. Are joined by friction welding.

It is desirable to carry out carburizing and quenching after the friction welding, which can be used for a counter shaft in which the inside is hollow and the two shafts are joined in the hollow portion.
Also, it can be used when the metal materials of the two shafts are different from each other.

[0007]

[Function] The shaft material is divided into two parts and individually forged. A hollow part is provided in each of the divided shaft materials, and the joint ends of the two shaft materials are formed into substantially the same shape. Are joined by friction welding and subjected to necessary machining, and then carburized and quenched.

As a result, the center portion of the counter shaft material can be formed hollow, and the forging method can be changed to the vertical stamping method, so that the rib portion to be gear processed can be thinned. The weight can be reduced.

By carburizing and quenching, the structure of the joint is uniform and continuous, and sufficient strength can be obtained.

[0010]

Embodiments of the present invention will now be described with reference to the drawings. 1 is a partial cross-sectional view showing the structure of an embodiment of the present invention, FIG.
(A) And (b) is a division sectional view of a counter shaft material in an example of the present invention.

The counter shaft material in the embodiment of the present invention is
A first shaft blank 1 in which a hollow portion 1a is provided in the central portion of the shaft and lightening portions 2a are provided on both sides of a rib portion 2 in which a gear is machined, and The two shaft blanks 3 are joined together by the joining ends 1b and 3b.

The manufacturing method is shown in FIGS. 2 (a) and 2 (b).
The joint end portion 1b of the first shaft blank 1 obtained by individually forging using the mold for the first shaft blank 1 and the mold for the second shaft blank 3 shown in FIG. And the connecting end 3b of the second shaft blank 3 are butted against each other and joined by friction welding.

The connection is made by joining end portion 1 of first shaft blank 1.
b and the joint end portion 3b of the second shaft blank 3 are abutted against each other as shown in FIG. 1, and the first shaft blank 1 and the second shaft blank 3 are relatively rotated by press-contacting each other by applying an external force in the arrow direction. Then, frictional heat is generated on the contact surface, and when heating by the frictional heat reaches a predetermined condition, a larger force is applied to perform pressure contact.

After the joining process is completed, the required mechanical working is carried out, and the carburizing and quenching treatment is carried out to enhance the mechanical strength of the joining portion 4.

The heat treatment after the joining process may be performed by induction heating in addition to carburizing and quenching.

[0016]

As described above, according to the present invention, it is possible to provide a hollow portion by dividing the counter shaft into two parts and forging them individually, and the conventional horizontal striking method is used. Since the forging method can be changed to the vertical driving method, the rib portion can be thinned and the weight can be reduced by 10 to 15%. Further, the die is downsized by the division, and the production can be performed by a general-purpose forging facility, so that the production cost can be reduced.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing the configuration of a counter shaft according to an embodiment of the present invention.

FIG. 2A is a sectional view showing a shape of a first shaft blank in the embodiment of the present invention, and FIG. 2B is a sectional view showing a shape of a second shaft blank in the embodiment of the present invention.

FIG. 3 is a view showing a shape of an integrally forged shaft material in a conventional example.

[Explanation of Codes] 1 First shaft material 1a, 3a Hollow part 1b, 3b Joining end part 2 Rib part 2a Lightening part 3 Second shaft material 4 Joining part

Claims (4)

[Claims] 1. A method for manufacturing a single counter shaft by separately manufacturing two shafts by forging, and joining the two shafts with their shaft centers aligned with each other. The inside of the shaft is hollow up to the axial distance from the joint end, and the joint ends of the two shafts are processed into almost the same shape, and both joint ends are joined by friction welding. A method of manufacturing a characteristic counter shaft. 2. The method of manufacturing a counter shaft according to claim 1, wherein carburizing and quenching is performed after the friction welding. 3. A counter shaft having a hollow inside, and two shafts joined at the hollow portion. 4. The counter shaft according to claim 3, wherein the metal materials of the two shafts are different from each other.