JP2011051037A - Spline machining method and spline shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spline machining method capable of eliminating the need of the frequent exchange of a broach die even if the broach die is worn by repeating machining by the broach die of a resin layer of a spline shaft. <P>SOLUTION: After forming a resin layer on a surface of teeth of the spline shaft, while the temperature of the resin layer is raised rather than a normal temperature, the spline shaft is inserted in the broach die, thereby machining the resin layer. Therefore, the spline shaft having an over pin diameter smaller than the case that the resin layer is machined at the normal temperature can be obtained. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is incorporated in a steering shaft of a vehicle and has a resin surface on a spline shaft such as a telescopic shaft for vehicle steering in which a male shaft and a female shaft are fitted in a non-rotatable and slidable manner to form a predetermined overpin diameter. The present invention relates to a spline processing method and a manufactured spline shaft.

  The telescopic shaft of the steering mechanism portion of the automobile is required to absorb the axial displacement generated when the automobile travels and to transmit the displacement and vibration on the steering wheel. Further, in order to obtain an optimum position for the driver to drive the automobile, a function of moving the position of the steering wheel in the axial direction and adjusting the position is required. In any of these cases, the telescopic shaft is required to reduce the rattling noise, reduce the rattling on the steering wheel, and reduce the sliding resistance during the sliding operation in the axial direction. .

  Conventionally, the spline surface of a spline shaft such as a telescopic shaft for vehicle steering has been coated with a resin layer made of nylon resin or the like for the purpose of noise reduction, wear resistance, reduction of sliding load, and the like. In the formation of this resin layer, the resin layer is formed thick, and then finished to a predetermined film thickness by broaching or cutting.

  However, in the conventional broaching, the broaching-type teeth and the spline shaft teeth do not exactly match in the circumferential direction. For this reason, when trying to finish the film thickness of the resin layer to 200 μm or less by conventional broaching, there is a problem that the film thickness of the resin layer is different on the left and right sides of the spline shaft teeth, and the base is exposed in a severe case. .

  As a prior art for improving this part, there is Japanese Patent No. 3851101, in which the positional relationship is determined so that the distance between the broached teeth and the spline shaft teeth is uniform in the circumferential direction. By passing the spline shaft through the broach mold, the film thickness of the resin layer is uniformly finished.

  However, in this prior art, the broach die is worn by repeated processing of the resin layer of the spline shaft with the broach die, and the overpin diameter of the spline after processing changes, so the broach die is frequently used. There was a problem that had to be replaced. Furthermore, since the diameter of the broach mold is selected according to the diameter of the female shaft fitted to the spline shaft, and the spline shaft is finished, there is a problem that a large number of size differences in the diameter of the broach mold must be prepared. .

Japanese Patent No. 3851101

  The problem to be solved by the present invention is a problem that the broach die must be frequently replaced and / or a problem that a large number of size differences in the diameter of the broach die must be prepared.

  In order to solve the above-mentioned problem, the first invention is the spline processing method of forming a resin layer on the tooth surface of the spline shaft and then finishing the resin layer to a predetermined overpin diameter by broaching. Thereafter, the resin layer is processed by passing the spline shaft through a broach die in a state where the temperature of the resin layer is raised or lowered from normal temperature.

  The second invention is characterized in that, in the first invention, the resin layer is processed in a state in which the temperature of the resin layer is raised from room temperature.

  In addition, a third invention is characterized in that, in the first invention, the resin layer is processed in a state where the temperature of the resin layer is lower than room temperature.

  According to the present invention, the temperature of the resin layer of the spline shaft is adjusted according to the degree of wear of the broach die by repeatedly processing the resin layer of the spline shaft with the broach die, and then the resin layer is finished thereon, It is possible to adjust the diameter of the overpin of the spline shaft at the same time, and the frequency of replacing the broach die can be reduced. And / or by enabling the adjustment of the overpin diameter of the spline shaft, there is an effect that it is not necessary to prepare a large amount of difference in the diameter of the broach die.

It is a partial cross section side view for showing an example of the broaching method in the spline processing method of this invention. FIG. 2 is an enlarged front sectional view showing the spline shaft before performing broaching according to the first embodiment. FIG. 3 is an enlarged front cross-sectional view showing a state of a spline shaft that has been broached in a state where the temperature of a resin layer in the spline shaft of FIG. 2 is raised. FIG. 4 is an enlarged front sectional view showing the spline shaft after the temperature of the resin layer of the spline shaft in FIG. 3 is cooled to room temperature. It is a front cross-sectional enlarged view which shows the spline shaft after cooling the temperature of the resin layer of the spline shaft after performing broaching of 2nd Embodiment to normal temperature.

(First embodiment)
FIG. 1 is a partial cross-sectional side view for illustrating a broaching method in one embodiment of a spline processing method according to the present invention, and FIG. 2 is a diagram before performing broaching of the first embodiment according to the present invention. FIG. 3 is an enlarged front sectional view showing the spline shaft. FIG. 3 is an enlarged front sectional view showing the spline shaft after broaching in a state where the temperature of the resin layer of the spline shaft in FIG. 2 is raised. FIG. 4 is an enlarged front sectional view showing the spline shaft after the temperature of the resin layer of the spline shaft in FIG. 3 is cooled to room temperature. Hereinafter, the spline processing method will be described with reference to the drawings.

  In the spline processing method of the present embodiment, the resin layer 3 is formed when the resin powder adheres to the spline shaft 1 and is melted by heat. Here, the resin layer 3 is formed thicker than the required film thickness.

  Next, heat is applied to the resin layer 3 to expand the resin. The broaching die 2 and the spline shaft 1 are moved relative to each other in the axial direction of the spline shaft 1, whereby the resin layer 3 is scraped off by the broaching die 2 and finished into a spline shaft having a predetermined overpin diameter. By processing in this way, as a result, more resin layers are scraped off than when no heat is applied.

  Thereafter, the resin layer 3 is cooled to room temperature. By processing as described above, the overpin diameter can be made smaller than when processing without applying heat.

  The linear expansion coefficient of the resin in this embodiment is about 4 to 25 × 10 −5 / ° C., and the film thickness after finishing by the broach die of the resin coated on the spline shaft is in the range of 0.05 to 1.5 mm. is there. The linear expansion coefficient is 25 × 10-5 / ° C, the resin product film thickness is 1.5mm, and the ambient temperature of the production line is 23 ° C.

When the temperature of the resin of the spline shaft is 150 ° C., the resin film thickness becomes 1.5 mm when processed with a broach mold to a film thickness of 1.5 mm. When the spline shaft is returned to room temperature, the resin film thickness can be reduced to 1.452 mm. In this way, the film thickness after cutting can be calculated while the conditions other than heat are the same.
By using this film thickness adjustment method, the overpin diameter of the spline shaft can be adjusted.

  As a method of applying heat to the resin, heating may be performed by an induction heater, bringing a heated object close or in contact, applying hot air, or heat conduction. The method for cooling may be the same as when applying heat.

  Next, FIG. 5 is an enlarged front sectional view showing the spline shaft of the second embodiment according to the present embodiment. In addition, the same code | symbol is attached | subjected to the same component as the spline shaft shown in FIG. 4, and the description is abbreviate | omitted.

  The spline shaft of this embodiment is obtained by performing broaching in a state where the temperature is raised to a temperature lower than the temperature of the resin layer before broaching in the first embodiment. FIG. 5 is an enlarged front cross-sectional view showing the spline shaft after the temperature of the resin layer 3 of the spline shaft 1 is cooled to room temperature. As a result, a smaller amount of the resin layer is scraped off as compared with the first embodiment. As a result, the overpin diameter of the spline shaft can be increased.

  In the present embodiment, broaching is performed in a state where the temperature of the resin layer before broaching is raised above room temperature, but the present invention is not limited to this, for example, the temperature of the resin layer before broaching Broaching may be performed with the temperature lower than the normal temperature. Moreover, in this Embodiment, although the broach is used for the process of the resin layer, it is not restricted to this, You may use a finishing tool.

  INDUSTRIAL APPLICABILITY The present invention can be used for a spline shaft such as a telescopic shaft for vehicle steering in which a male shaft and a female shaft are fitted in a steering shaft of a vehicle so that the male shaft and the female shaft are not rotatable and slidable.

1 Spline shaft 2 Broach type 3 Resin layer

Claims (3)

  In the spline processing method of forming a resin layer on the tooth surface of the spline shaft and then finishing the resin layer to a predetermined overpin diameter by broaching, after the resin layer is formed, the temperature of the resin layer is changed from room temperature The spline processing method is characterized in that the resin layer is processed by passing the spline shaft through a broach die.   The spline processing method according to claim 1, wherein the resin layer is processed in a state where the temperature of the resin layer is higher than normal temperature.   The spline processing method according to claim 1, wherein the resin layer is processed in a state where the temperature of the resin layer is lower than normal temperature.

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