JP2011110680A - Spline machining method and spline shaft - Google Patents

Abstract

A spline processing method for a spline shaft and a spline shaft capable of smoothing expansion and contraction in the axial direction of the spline shaft are provided.
A spline processing method in which a resin layer is formed on a tooth surface of a spline shaft and then the resin layer is finished to a predetermined overpin diameter by broaching. The resin layer is processed by passing the spline shaft through a broaching mold in a state where the temperature is raised from room temperature.
[Selection] Figure 1

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. A spline shaft indicates a male spline unless otherwise specified.

  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, by processing the resin layer of the spline shaft with a broach die, the overpin diameter of the spline after processing becomes uniform in the axial direction. If it becomes uniform in the axial direction, there is a problem that when the spline shaft expands and contracts in the axial direction, the corner of the male spline at the end in the axial direction gets caught with the female spline and the axial expansion and contraction may not be smooth. It was.

Japanese Patent No. 3851101

  The problem to be solved by the present invention is to provide a spline shaft spline processing method and a spline shaft that can smooth the expansion and contraction of the spline shaft in the axial direction.

  In order to solve the above problem, a spline processing method according to claim 1 of the present invention is a spline processing in which a resin layer is formed on the tooth surface of the spline shaft and then the resin layer is finished to a predetermined overpin diameter by broaching. In the method, after the resin layer is formed, the resin layer is processed by passing the spline shaft through a broach die in a state where the temperature of the resin layer at both axial end positions is higher than room temperature.

  The spline processing method according to claim 2 of the present invention is the spline processing method in which a resin layer is formed on the tooth surface of the spline shaft and then the resin layer is finished to a predetermined overpin diameter by broaching. Then, the resin layer is processed by passing the spline shaft through a broach die in a state where the temperature of the resin layer in the intermediate portion in the axial direction is lower than room temperature.

  A spline shaft according to a third aspect of the present invention is processed by the processing method according to the first or second aspect.

  According to the present invention, both ends of the male spline have an effect that the diameter of the overpin is reduced and smooth axial contraction is possible without causing a catch with the female spline.

It is a partial cross section side view for showing the broaching method in one embodiment of the spline processing method concerning the present invention. FIG. 5 is a partial cross-sectional side view showing the spline shaft before performing broaching according to the first embodiment of the present invention. It is a partial cross section side view which shows the state which raised the temperature of the axial direction both ends position of the resin layer of the spline shaft of FIG. It is a partial cross section side view which shows the spline shaft after performing broaching of the spline shaft of FIG. It is a partial cross section side view which shows the spline shaft after cooling the temperature of the resin layer of the spline shaft of FIG. 4 to normal temperature. FIG. 6 is an enlarged front cross-sectional view taken along line AA in FIG. 5. It is a front cross-sectional enlarged view along the BB line of FIG. It is a partial cross section side view which shows the state which cooled the axial direction intermediate part of the resin layer of the spline shaft before performing broaching of 2nd Embodiment which concerns on this invention.

(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 in the first embodiment according to the present invention. FIG. 3 is a partial cross-sectional side view showing the spline shaft, FIG. 3 is a partial cross-sectional side view showing a state in which the temperature at both axial end positions of the resin layer of the spline shaft in FIG. 2 is raised, and FIG. It is a partial cross section side view which shows the spline shaft after performing the broach process of a spline shaft, and a dotted line part shows the resin layer scraped off by the process by a broach type | mold. 5 is a partial cross-sectional side view showing the spline shaft after the temperature of the resin layer of the spline shaft in FIG. 4 is cooled to room temperature, and FIG. 6 is an enlarged front cross-sectional view along the line AA in FIG. FIG. 7 is an enlarged front sectional view taken along line BB in FIG. 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, the resin is expanded by applying heat to the resin layers 3 at both axial end positions of the resin layer of the spline shaft. 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, the resin layers at both ends in the axial direction of the resin layer of the spline shaft to which heat has been applied will eventually scrape off more resin layers than the resin layer at the intermediate portion in the axial direction.

  Thereafter, the resin layer 3 is cooled to room temperature. By processing as described above, the overpin diameter at both axial end positions of the resin layer of the spline shaft can be reduced.

  The spline shaft made as described above has a small overpin diameter at both axial end positions of the resin layer and a large overpin diameter at the axial intermediate portion of the resin layer. The axial expansion and contraction of the spline shaft can be smoothed without causing the corners of the axial ends of the splines to catch on the female splines.

  As a method of applying heat to the resin, the metal part inside the shaft may be induction-heated with an induction heater, the heated object may be brought close to or brought into contact, hot air may be applied, heat conduction may be used.

(Second embodiment)
FIG. 8 is a partial cross-sectional side view showing a state in which the axial intermediate portion of the resin layer of the spline shaft before performing broaching according to the second embodiment of the present invention is cooled.

  In the second embodiment, the resin layer 3 at the intermediate portion in the axial direction of the resin layer of the spline shaft is cooled to shrink 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, the resin layers at both axial end positions of the uncooled spline shaft resin layer eventually scrape off more resin layers than the resin layer at the axial intermediate portion.

  Thereafter, the resin layer 3 is warmed to room temperature. By processing as described above, the overpin diameter at both axial end positions of the resin layer of the spline shaft can be reduced.

  The spline shaft made as described above has a small overpin diameter at both axial end positions of the resin layer and a large overpin diameter at the axial intermediate portion of the resin layer. The axial expansion and contraction of the spline shaft can be smoothed without causing the corners of the axial ends of the splines to catch on the female splines.

  As a method for cooling the resin, the resin may be cooled by bringing a cooled object close to or in contact with the resin, or by applying cold air.

  In the present embodiment, the broach is used for processing the resin layer, but the present invention is not limited to this, and a finishing tool may be used.

  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 vehicle steering shaft so that the male shaft and the female shaft are non-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 forming the resin layer, the temperature of the resin layer at both axial end positions is set to room temperature. A spline processing method, wherein the resin layer is processed by passing the spline shaft through a broaching mold in a raised state.   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 forming the resin layer, the temperature of the resin layer in the axial middle portion is set to room temperature. A spline processing method, wherein the resin layer is processed by passing the spline shaft through a broach die in a lowered state.   A spline shaft machined by the machining method according to claim 1 or 2.

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