JP2015131551A - Shaft manufacturing method and shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a shaft which can connect a first shaft and a second shaft without causing wobbling in a simple procedure while reducing a manufacturing cost, and the shaft.SOLUTION: A shaft 40 includes an intermediate shaft 12 and a hollow upper shaft 11. The intermediate shaft 12 has an external peripheral face 12A on which a male spline 33 is formed. The upper shaft 11 has an internal peripheral face 11A on which a female spline 35 engaged with the male spline 33 is formed. A manufacturing method of the shaft 40 includes a first process for attaching a resin sheet 37 to the intermediate shaft 12 so as to cover at least a part of a surface 33A of the male spline 33, and a second process for pressure-inserting the intermediate shaft 12 attached with the resin sheet 37 into the upper shaft 11, and making the male spline 33 and the female spline 35 spline-engaged with each other.

Description

  The present invention relates to, for example, a method for manufacturing a shaft constituting a steering device for a vehicle and the shaft.

  In the telescopic shaft disclosed in Patent Document 1 below, male serrations are engraved on the upper shaft. A female serration that fits into the male serration is formed on the inner peripheral surface of the lower shaft. The male serration is divided into two in the axial direction, and axial details are formed at the site (between the two male serrations). A backlash preventing member made of an elastic body such as a leaf spring is fitted to the shaft details. The backlash between the upper shaft and the lower shaft can be suppressed by the spring stress (also referred to as elastic force) of the backlash preventing member, and a predetermined sliding resistance can be generated between the upper shaft and the lower shaft.

  The telescopic shaft disclosed in Patent Document 2 below includes a male shaft and a female shaft. The male shaft has protruding teeth as a non-circular outer peripheral shape. The female shaft is formed in a hollow cylindrical shape, and a tooth groove is formed on the inner periphery thereof. The male shaft is coupled to the female shaft so that rotational torque can be transmitted. The protruding teeth of the male shaft are covered with a covering portion made of a polymer material. The inner periphery of the covering portion is bonded to the tooth surface of the protruding tooth with an adhesive. The covering portion reduces the sliding resistance between the protruding tooth and the tooth groove that is generated when the telescopic shaft expands and contracts.

Utility Model Registration No. 2593916 JP 2013-142437 A

In the telescopic shaft of Patent Document 1, since it is necessary to cut the male serration in order to provide the groove-shaped shaft details for fitting the anti-rattle member between the male serrations, There is a risk that the manufacturing cost increases.
In addition, when the upper shaft is hollow, the grooves constituting the shaft details must be shallowed in order to prevent the strength of the upper shaft from being insufficient. Therefore, a backlash preventing member is accommodated between the shaft details and the lower shaft. Only a small gap can be provided as a space. In this case, in order to adjust the size of the gap between the male serration and the female serration (hereinafter referred to as the gap amount) and the spring stress of the rattle prevention member, variations in the dimensional accuracy of the male serration and female serration, It is necessary to finely manage the dimensions of the prevention member. This may further increase the manufacturing cost of the telescopic shaft.

  Moreover, when manufacturing the expansion-contraction shaft of patent document 2, since the process of coating a coating part on a protruding tooth and the process of adhere | attaching a protruding tooth and a coating part are required, there exists a possibility that the manufacturing cost of an expansion / contraction shaft may increase. There is. Furthermore, it is necessary to finely manage the thickness of the covering portion in order to adjust the gap between the male shaft and the female shaft and the sliding resistance between these shafts. This may increase the manufacturing cost of the telescopic shaft.

  The present invention has been made under such a background, and a method of manufacturing a shaft capable of connecting the first shaft and the second shaft without rattling by a simple procedure while reducing the manufacturing cost. And it aims at providing the said shaft.

  In the first aspect of the present invention, a first shaft (12) having an outer peripheral surface (12A) on which a male spline (33) is formed, and a female spline (35) that is spline-fitted with the male spline are formed. A method of manufacturing a shaft (40) including a hollow second shaft (11) having a peripheral surface (11A), the resin sheet (37) covering at least a part of the surface (33A) of the male spline. , 38, 39, 49) are attached to the first shaft, the first shaft to which the resin sheet is attached is press-fitted into the second shaft, and the male spline and the female spline are fitted by spline fitting. And a second step of combining the shafts with each other.

The invention according to claim 2 is characterized in that, in the first step, at least one of the resin sheets is aligned with the end surface (12B) on the distal end side inserted into the second shaft in the first shaft. It is attached so that it may be bent in the axial direction (X) of the said 1st shaft, The manufacturing method of the shaft of Claim 1 characterized by the above-mentioned.
The invention according to claim 3 is the shaft manufacturing method according to claim 1, wherein in the first step, at least one resin sheet is spirally wound around the outer peripheral surface of the first shaft. is there.

Invention of Claim 4 is a shaft characterized by including the said 1st shaft and the said 2nd shaft, and being manufactured by the manufacturing method in any one of Claims 1-3.
In addition, in the above, the numbers in parentheses represent reference numerals of corresponding components in the embodiments described later, but the scope of the claims is not limited by these reference numerals.

  According to the first and fourth aspects of the present invention, the first shaft having the male spline formed on the outer peripheral surface and the second shaft having the female spline formed on the inner peripheral surface are spline-fitted, so that one The shaft is configured. When manufacturing this structured shaft, the resin sheet is attached to the first shaft so as to cover at least part of the surface of the male spline of the first shaft, and then the first shaft to which the resin sheet is attached is The male spline and the female spline are spline-fitted by being press-fitted into the second shaft.

The male spline and the female spline are engaged with each other with play due to the configuration in which the spline is engaged.
Here, when the first shaft is press-fitted into the second shaft, the resin sheet attached to the first shaft is compressed and deformed along the gap so as to fill the gap between the male spline and the female spline. Thereby, there is no play between the first shaft and the second shaft, and the first shaft and the second shaft are connected without rattling. That is, the first shaft to which the resin sheet is attached without going through a complicated process such as cutting the first shaft or the like to coat the elastic member for eliminating the play or coating the male spline or the like. The first shaft and the second shaft can be connected without rattling while reducing the manufacturing cost by a simple procedure such as press fitting into the second shaft.

  In addition, the size of the gap between the male spline and the female spline (gap amount) and the sliding resistance between the male spline and the female spline vary depending on the dimensional accuracy (finish accuracy) of the male spline and female spline. obtain. However, the gap amount and sliding resistance can be arbitrarily controlled simply by adjusting the thickness of the resin sheet according to the finishing accuracy of the spline.

  According to the second aspect of the present invention, the at least one resin sheet is attached so as to be bent in the axial direction of the first shaft after being along the end surface of the first shaft inserted into the second shaft. It has been. For this reason, when the first shaft is press-fitted into the second shaft, the resin sheet can be surely provided with a gap between the male spline and the female spline without being detached from the first shaft in a state of being caught by the end surface on the distal end side of the first shaft. Can be buried.

  According to the third aspect of the present invention, the resin sheet can cover the male spline in a relatively wide range by winding at least one resin sheet spirally around the outer peripheral surface of the first shaft. Thereby, since the resin sheet can fill the gap between the male spline and the female spline in a relatively wide range, rattling between the first shaft and the second shaft can be reliably eliminated.

FIG. 1 is a schematic side view of a steering device 1 according to an embodiment of the present invention. FIG. 2 is a view showing a cross section of the main part of the steering shaft 3 and its periphery. 3A is a view of a cross section of the intermediate shaft 12 taken along the line III-III in FIG. 2 as viewed from the steering member 2 side, and FIG. 3B is taken along the line III-III in FIG. FIG. 6 is a view of a cross section of the upper shaft 11 viewed from the steering member 2 side. FIG. 4 is a schematic diagram illustrating a first step that is a part of the manufacturing process of the shaft 40. FIG. 5 is a schematic diagram showing the next step (second step) of FIG. FIG. 6 is an enlarged view of a cross section taken along line III-III in FIG. FIG. 7 is a diagram showing a first step in the first modification. FIG. 8 is a diagram showing a first step in the second modification. FIG. 9 is a schematic perspective view showing a first step in the third modification.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic side view of a steering device 1 according to an embodiment of the present invention. Here, in FIG. 1, the left side of the drawing is the front side of the vehicle body 9 equipped with the steering device 1, the right side of the drawing is the rear side of the vehicle body 9, and the upper side of the drawing is the upper side of the vehicle body 9. The side is the lower side of the vehicle body 9.

First, an outline of the steering device 1 will be described.
With reference to FIG. 1, in the steering device 1, a steering shaft 3 with a steering member 2 connected to one end is connected to a steering mechanism A through a universal joint 4, an intermediate shaft 5, a universal joint 6 and a pinion shaft 7 in order. Has been. The steering shaft 3 is rotated around the axis by the steering torque transmitted from the steering member 2, and this rotation is transmitted to the steering mechanism A.

The steering mechanism A is configured by a rack and pinion mechanism or the like. The steering mechanism A turns steered wheels such as tires (not shown) in response to the rotation of the steering shaft 3 being transmitted.
The steering shaft 3 is substantially cylindrical. Here, the direction in which the steering shaft 3 extends (the direction extending from the lower left to the upper right in the drawing of FIG. 1) is defined as the axial direction X. A symbol “X1” is attached behind the axial direction X, and a symbol “X2” is attached ahead of the axial direction X. Further, among the directions orthogonal to the axial direction X, a direction perpendicular to the paper surface in FIG. 1 is referred to as a left-right direction Y, and a direction extending up and down in FIG. In the drawings subsequent to FIG. 2, directions corresponding to the respective directions in FIG. 1 are denoted by the same reference numerals as those in FIG. 1.

The steering shaft 3 includes an intermediate shaft 12 as a first shaft, an upper shaft 11 as a second shaft, an input shaft 13, an output shaft 14, and a torsion bar 15.
FIG. 2 is a view showing a cross section of the main part of the steering shaft 3 and its periphery. In FIG. 2, the axial direction X is horizontal along for convenience of explanation.

Referring to FIG. 2, the upper shaft 11 is hollow and has a substantially cylindrical shape extending in the axial direction X.
The entire intermediate shaft 12 has a substantially columnar shape or a substantially cylindrical shape extending in the axial direction X. The intermediate shaft 12 includes a connecting portion 41 that is an end portion on the front X2 side, a large-diameter portion 42 on the rear X1 side of the connecting portion 41, and a small-diameter portion 43 that relays between the connecting portion 41 and the large-diameter portion 42. Is included. The connection part 41 is substantially cylindrical. The large diameter portion 42 has a substantially columnar shape or a substantially cylindrical shape. The small diameter portion 43 has a smaller diameter than the connecting portion 41 and the large diameter portion 42. The intermediate shaft 12 is connected to the upper shaft 11 so as to be integrally rotatable by inserting the large-diameter portion 42 into the upper shaft 11. The input shaft 13 is connected to the intermediate shaft 12 so as to be integrally rotatable by inserting the end portion on the rear X1 side with respect to the connecting portion 41 of the intermediate shaft 12.

Details of the upper shaft 11 and the intermediate shaft 12 will be described later.
Referring to FIG. 1, the steering shaft 3 includes an output shaft 14 to which the universal joint 4 is connected, and a torsion bar 15 that connects the input shaft 13 and the output shaft 14. The upper shaft 11, the intermediate shaft 12, the input shaft 13, the torsion bar 15, and the output shaft 14 are coaxially arranged in this order from the rear X1 side.

Steering device 1 further includes an electric motor 16, a reduction device 17, a torque sensor 20, an ECU (Electronic Control Unit) 21, a steering tube 22, an upper bracket 26, and a lower bracket 27. It is out. Note that other components described below also constitute the steering device 1.
The electric motor 16 generates a steering assist force. The reduction gear 17 transmits the power generated by the electric motor 16 to the output shaft 14. The reduction gear 17 further includes a worm 18 that is rotationally driven by the electric motor 16 and a worm wheel 19 that meshes with the worm 18. The worm wheel 19 is connected to the output shaft 14 so as to be integrally rotatable.

The torque sensor 20 detects the steering torque based on the relative rotational displacement between the input shaft 13 and the output shaft 14 via the torsion bar 15.
The ECU 21 controls the drive of the electric motor 16 based on a torque detection result given from the torque sensor 20 or a vehicle speed detection result given from a vehicle speed sensor (not shown). The output rotation of the electric motor 16 is decelerated via the speed reducer 17, transmitted to the pinion shaft 7 via the output shaft 14, and further transmitted to the steering mechanism A.

The steering tube 22 is a hollow body that extends in the axial direction X as a whole. The steering tube 22 accommodates the steering shaft 3. The steering tube 22 includes an upper tube 23, a lower tube 24, and a housing 25.
The upper tube 23 and the lower tube 24 have a cylindrical shape extending in the axial direction X. The upper tube 23 is disposed on the rear X1 side with respect to the lower tube 24. The upper tube 23 is connected to the upper shaft 11 via a bearing 28 at the rear end.

The front end portion of the upper tube 23 is inserted from the rear X1 side with respect to the rear end portion of the lower tube 24. The front end portion of the lower tube 24 is inserted from the rear X1 side with respect to the rear end portion of the housing 25. Further, the front end portion of the housing 25 is connected to the output shaft 14 via a bearing 29.
The lower bracket 27 supports the housing 25 and connects the front X2 side of the steering device 1 to the vehicle body 9. The lower bracket 27 includes a fixed bracket 30 fixed to the vehicle body 9, a movable bracket 31 fixed to the housing 25, and a central shaft 32 extending in the left-right direction Y. The movable bracket 31 is rotatably supported by the fixed bracket 30 via the central shaft 32. Therefore, the entire steering device 1 can rotate around the central shaft 32. This rotation is called “tilt”.

The upper bracket 26 supports the upper tube 23 in a tiltable manner, and connects the rear X1 side of the steering device 1 to the vehicle body 9.
Next, the upper shaft 11 and the intermediate shaft 12 will be described in detail.
3A is a view of a cross section of the intermediate shaft 12 taken along the line III-III in FIG. 2 as viewed from the steering member 2 side, and FIG. 3B is taken along the line III-III in FIG. FIG. 6 is a view of a cross section of the upper shaft 11 viewed from the steering member 2 side.

  Referring to FIG. 3A, the intermediate shaft 12 has an outer peripheral surface 12 </ b> A in which a male spline 33 is formed in the large diameter portion 42. The male spline 33 includes a plurality of first tooth portions 34 and a first groove portion 46. Each first tooth 34 and the first groove 46 extend in the axial direction X. The first tooth portions 34 and the first groove portions 46 are alternately arranged along the circumferential direction C of the outer peripheral surface 12A. The plurality of first tooth portions 34 are arranged along the circumferential direction C at a uniform pitch P1. The plurality of first groove portions 46 are also arranged along the circumferential direction C at a uniform pitch P1.

The outer peripheral surface 12A of the large diameter portion 42 constitutes the surface 33A of the male spline 33.
Further, the end surface 12B on the rear X1 side in the intermediate shaft 12 is a flat surface orthogonal to the axial direction X (see FIG. 2).
Referring to FIG. 3B, the upper shaft 11 has an inner peripheral surface 11A on which a female spline 35 is formed at the front end. The inner peripheral surface 11A is exposed to the front X1 at the end of the upper shaft 11 on the front X1 side (see FIG. 2). The female spline 35 is constituted by a plurality of second tooth portions 36 and second groove portions 47. Each second tooth portion 36 and the second groove portion 47 extend in the axial direction X. The second tooth portions 36 and the second groove portions 47 are alternately arranged along the circumferential direction of the upper shaft 11 (the same as the circumferential direction C described above). The plurality of second tooth portions 36 are arranged along the circumferential direction C at a uniform pitch P2. The plurality of second groove portions 47 are arranged along the circumferential direction C at a uniform pitch P2. Since the pitch P2 is substantially equal to the pitch P1 of the plurality of first tooth portions 34, the male spline 33 and the female spline 35 can be spline-fitted.

  Referring to FIG. 2, upper shaft 11 and intermediate shaft 12 are connected by spline fitting in a state where intermediate shaft 12 is inserted from the front X2 side with respect to the front end portion of upper shaft 11. In the steering shaft 3, the connected upper shaft 11 and the intermediate shaft 12 constitute a shaft 40. The shaft 40 can contract in the axial direction X when an impact is transmitted from the steering member 2 in a so-called secondary collision of the vehicle. The shaft 40 does not need to contract during normal times other than during a secondary collision.

In the shaft 40, a resin sheet 37 is interposed between the upper shaft 11 and the intermediate shaft 12.
Next, a method for manufacturing the shaft 40 having the resin sheet 37 will be described.
FIG. 4 is a schematic diagram illustrating a first step that is a part of the manufacturing process of the shaft 40.
Referring to FIG. 4, resin sheet 37 is made of, for example, stretchable Teflon (registered trademark) or resin nylon, is a strip-shaped sheet having an elongated rectangular shape, and has a thickness T.

Hereinafter, the manufacturing process of the shaft 40 is divided into a first process and a second process in chronological order, and each process will be described.
First, in the first step, the central portion 37A in the up-down direction Z of the resin sheet 37 arranged so as to be longitudinal in the left-right direction Y is set along the end surface 12B on the rear X1 side of the intermediate shaft 12. From this state, the resin sheet 37 is attached to the intermediate shaft 12 so as to be bent in the axial direction X by moving both side portions 37B in the vertical direction Z of the resin sheet 37 to the front X2 side. In this state, both side portions 37 </ b> B are in contact with a part of the outer peripheral surface 12 </ b> A in the large diameter portion 42 of the intermediate shaft 12. In other words, both side portions 37 </ b> B of the resin sheet 37 cover a part of the surface 33 </ b> A of the male spline 33. The part is two places on the circumference of the surface 33A of the male spline 33, and is almost the entire region in the axial direction X at the two places. Therefore, the large-diameter portion 42 of the intermediate shaft 12 is inserted inside the substantially U-shaped resin sheet 37 and is sandwiched between both side portions 37B of the resin sheet 37 while being caught by the central portion 37A. Yes.

Thus, in the first step, the resin sheet 37 is attached to the intermediate shaft 12 so as to cover at least a part of the surface 33A of the male spline 33.
FIG. 5 is a schematic diagram showing the next step (second step) of FIG. FIG. 6 is an enlarged view of a cross section taken along line III-III in FIG.
With reference to FIG. 5, next, the second step after the first step will be described. In FIG. 5, the resin sheet 37 is shown in black.

In the second step, first, the end surface 12B of the intermediate shaft 12 to which the resin sheet 37 is attached is made to face the rear X1 side and face the front X2 side end of the upper shaft 11 from the front X2 side. Therefore, the end surface 12 </ b> B is an end surface on the distal end side that is inserted into the upper shaft 11 in the intermediate shaft 12.
Next, the intermediate shaft 12 is press-fitted from the front X2 side to the end portion of the upper shaft 11 on the front X2 side. At that time, as shown in FIG. 6, the first tooth portion 34 of the male spline 33 and the second groove portion 47 of the female spline 35 are fitted together, and the first groove portion 46 of the male spline 33 and the second tooth portion of the female spline 35 are fitted. 36 and the male spline 33 and the female spline 35 are spline-fitted.

As described above, in the second step, the intermediate shaft 12 to which the resin sheet 37 is attached is press-fitted into the upper shaft 11 so that the male spline 33 and the female spline 35 are spline-fitted.
The male spline 33 and the female spline 35 are engaged with each other with play due to the spline fitting configuration. Further, in the gap 45 between the male spline 33 and the female spline 35, the size in the radial direction R of the intermediate shaft 12 is referred to as “gap amount t” (see FIG. 6).

Therefore, when the intermediate shaft 12 is press-fitted into the upper shaft 11, the resin sheet 37 can reliably fill the gap 45 without being detached from the intermediate shaft 12 in a state of being caught by the end surface 12 </ b> B on the distal end side of the intermediate shaft 12. it can.
Through the first and second steps described above, the shaft 40 with the resin sheet 37 interposed between the upper shaft 11 and the intermediate shaft 12 is completed.

When the resin sheet 37 is not interposed between the upper shaft 11 and the intermediate shaft 12, the upper shaft 11 and the intermediate shaft 12 are coupled with play. There is a rattling that becomes the source of abnormal noise.
Further, in order to generate a predetermined sliding resistance between the upper shaft 11 and the intermediate shaft 12 when absorbing the impact at the time of the secondary collision, the play between the upper shaft 11 and the intermediate shaft 12 is eliminated. There is a need. Here, the force with which the resin sheet 37 presses the intermediate shaft 12 against the upper shaft 11 in a region where the resin sheet 37 does not exist in order to generate a predetermined sliding resistance is referred to as “elastic force”.

  In the case of a conventional example in which an elastic member such as a leaf spring is used to eliminate play between the upper shaft 11 and the intermediate shaft 12, it is necessary to cut a part of the male spline 33 to provide an attachment portion in order to attach the elastic member. There is. However, when the intermediate shaft 12 is hollow, only a slight gap can be provided between the attachment portion and the female spline 35 of the upper shaft 11. Therefore, it is necessary to manage the dimension of the elastic member in accordance with the dimensional accuracy of the male spline 33 and the female spline 35 in order to adjust the gap amount and the elastic force, which may increase the processing cost.

In addition, as another conventional example, a configuration in which play between the intermediate shaft 12 and the upper shaft 11 is eliminated by caulking the upper shaft 11 to the intermediate shaft 12 is also conceivable. Similarly, dimensional management related to caulking is required, which may increase the processing cost.
Here, when the intermediate shaft 12 is press-fitted into the upper shaft 11, the resin sheet 37 attached to the intermediate shaft 12 is compressed and deformed along the gap 45 so as to fill the gap 45. In this state, the resin sheet 37 is compressed in the radial direction R in the second groove portion 47 until it has the same thickness as the gap amount t. As a result, there is no play between the intermediate shaft 12 and the upper shaft 11, and the intermediate shaft 12 and the upper shaft 11 are connected without rattling. In other words, the intermediate portion to which the resin sheet 37 is attached without going through a complicated process such as cutting the intermediate shaft 12 or the like or coating the male spline 33 or the like in order to dispose the elastic member for eliminating the play. The intermediate shaft 12 and the upper shaft 11 can be connected without rattling by a simple procedure of press-fitting the shaft 12 into the upper shaft 11 while reducing the manufacturing cost.

  Further, the gap amount t and the sliding resistance between the male spline 33 and the female spline 35 can vary depending on the dimensional accuracy (finish accuracy) of the male spline 33 and the female spline 35. However, only by adjusting the thickness T of the resin sheet 37 according to the finishing accuracy of the male spline 33 and the female spline 35, the gap amount and sliding resistance can be arbitrarily controlled.

Further, since the rattling between the upper shaft 11 and the intermediate shaft 12 is eliminated, it is possible to prevent the generation of abnormal noise generated between the upper shaft 11 and the intermediate shaft 12.
Next, a first modification of the present invention will be described.
FIG. 7 is a diagram showing a first step in the first modification. In FIG. 7, the same members as those described above are denoted by the same reference numerals, and the description thereof is omitted (the same applies to FIGS. 8 and 9 described later).

  With reference to FIG. 7, a plurality (two in this case) of resin sheets 37 of the first modification are attached to the intermediate shaft 12 in the first step described above. Specifically, after being aligned along the vertical direction Z of the resin sheet 37 that is long in the vertical direction Z (referred to as the first resin sheet 38 in the first modification), the central portion 38A in the vertical direction Z of the first resin sheet 38 is The intermediate shaft 12 extends along the end surface 12B on the rear X1 side. From this state, the first resin sheet 38 is bent in the axial direction X by moving both side portions 38B in the vertical direction Z to the front X2 side in the first resin sheet 38. Furthermore, a central portion 39A in the left-right direction Y of another resin sheet 37 (referred to as a second resin sheet 39) arranged so as to be longitudinal in the left-right direction Y crosses the central portion 38A in a cross shape from the rear X1 side. Overlap like so. Then, both side portions 39B in the left-right direction Y of the second resin sheet 39 are moved to the front X2 side to bend the second resin sheet 39 in the axial direction X.

In this way, in the first step, the plurality of resin sheets 37 may be attached so as to be bent in the axial direction X after being along the end surface 12B of the intermediate shaft 12.
Of course, in the first step, three or more resin sheets 37 may be attached to the intermediate shaft 12. In short, at least one resin sheet 37 may be attached in the first step.

Next, a second modification of the present invention will be described.
FIG. 8 is a diagram showing a first step in the second modification.
Referring to FIG. 8, in the first step of the second modification, the resin sheet 37 is wound around the outer peripheral surface 12 </ b> A of the intermediate shaft 12 in a spiral shape that proceeds in the axial direction X. Therefore, in the first step of the second modified example, the resin sheet 37 can be attached in a wider range in the circumferential direction C than in the first step of the present embodiment.

Thereby, since the resin sheet 37 can fill the gap 45 in a relatively wide range, rattling between the intermediate shaft 12 and the upper shaft 11 can be reliably eliminated.
A plurality of resin sheets 37 may be wound in a spiral shape. In short, in the first step in the second modification, at least one resin sheet 37 may be wound in a spiral shape.

FIG. 9 is a schematic perspective view showing a first step in the third modification.
Referring to FIG. 9, the resin sheet 49 of the third modified example has a rectangular shape (square shape or rectangular shape) extending in the vertical direction Z and the horizontal direction Y. In the first step of the third modification, the resin sheet 49 is applied to the center portion 49A in the left-right direction Y and the up-down direction Z to the end surface 12B on the rear X1 side of the intermediate shaft 12. From this state, by bending the outer edge portion 49B of the resin sheet 49 in the axial direction X, the resin sheet 49 is attached to the intermediate shaft 12 so as to wrap the male spline 33 of the intermediate shaft 12.

Thereby, since the resin sheet 49 can cover the male spline 33 in a wider range, the ratchet between the intermediate shaft 12 and the upper shaft 11 can be reliably eliminated in the completed shaft 40.
The present invention is not limited to the embodiment described above, and various modifications can be made within the scope of the claims.

For example, the shaft 40 may not be composed of the intermediate shaft 12 and the upper shaft 11, and may be applied to other shafts composed of two shafts that are spline-fitted, such as the intermediate shaft 5. be able to.
If the resin sheet 37 is durable enough to withstand repeated sliding of the intermediate shaft 12 and the upper shaft 11, it can be applied to a steering device capable of so-called telescopic adjustment. .

Further, the resin sheet 37 may have a cylindrical shape or a curved plate shape on the outer peripheral surface 12A of the intermediate shaft 12 from the stage before being attached to the intermediate shaft 12.
In addition, one resin sheet 37 may cover not only a part of the surface 33A of the male spline 33 but also the entire region.
Further, the length of each side portion 37 </ b> B in the axial direction X of the resin sheet 37 may be different from each other in a state where the resin sheet 37 is attached to the intermediate shaft 12.

  Further, the side portions 37B of the resin sheet 37 are not necessarily provided on both sides in the vertical direction Z, and may be provided on only one side of the vertical direction Z.

DESCRIPTION OF SYMBOLS 11 ... Upper shaft, 11A ... Inner peripheral surface, 12 ... Intermediate shaft, 12A ... Outer peripheral surface, 12B ... End surface, 33 ... Male spline, 33A ... Surface, 35 ... Female spline, 37 ... Resin sheet, 38 ... First resin sheet 39 ... second resin sheet, 40 ... shaft, 49 ... resin sheet, X ... axial direction

Claims (4)

A method of manufacturing a shaft, comprising: a first shaft having an outer peripheral surface on which a male spline is formed; and a hollow second shaft having an inner peripheral surface on which a female spline that is spline-fitted with the male spline is formed.
A first step of attaching a resin sheet to the first shaft so as to cover at least a part of the surface of the male spline;
A second step of press-fitting the first shaft to which the resin sheet is attached into the second shaft and fitting the male spline and the female spline to a spline;
The manufacturing method of the shaft characterized by including.   In the first step, at least one of the resin sheets is bent in the axial direction of the first shaft after being along the end surface of the first shaft inserted into the second shaft with respect to the second shaft. The shaft manufacturing method according to claim 1, wherein the shaft is attached.   The shaft manufacturing method according to claim 1, wherein in the first step, at least one of the resin sheets is spirally wound around an outer peripheral surface of the first shaft.   A shaft comprising the first shaft and the second shaft, wherein the shaft is manufactured by the manufacturing method according to claim 1.

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