JPH11208417A - Steering shaft and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a steering shaft lightweight and reduce its cost by forming a large-diameter section expanded in diameter by expansion machining at the prescribed position of a hollow material, and forming a bottomed recess coupled with a lock member on the outer peripheral face side of the large-diameter section. SOLUTION: The rotation of a steering shaft 1 is restricted by its coupling with a lock member, and the steering shaft 1 is formed with a steel hollow material 10. A small-diameter section 20 shrunk with the hollow material 10 in diameter is formed at one end section, and a large-diameter section 30 expanded with the hollow material 10 in diameter is formed at the prescribed position near the small-diameter section 20. A bottomed recess 40 penetrates between the erected faces 32 of the large-diameter section 30 erected from the outer periphery 11 of the hollow material 10 and gradually expanded in diameter toward the outer periphery 31 of the large-diameter section 30 along the axis of the hollow material 10. The steering shaft 1 can be made lightweight.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering shaft whose rotation is restricted by engagement with a lock member for preventing vehicle theft, and a method of manufacturing the same.

[0002]

2. Description of the Related Art FIG. 8 is a front view partially showing an example of a conventional product in a sectional view, and FIG. 9 is a sectional view taken along the line XX of FIG. As shown in FIGS. 8 and 9, this steering shaft a has a shaft main body b made of a hollow material made of metal having a circular cross section, and a pair of long holes c1 which engage with a lock member d for preventing vehicle theft. A metal engaging member c for restraining the rotation of the steering shaft a by engaging with the locking member d. The engaging member c is fitted to the outside of a predetermined portion of the shaft body b and fixed by welding. Have been.

[0003] One end of the shaft body b is reduced in diameter by a contraction process such as extrusion to form a small-diameter portion b1, and a serration portion into which the boss portion of the steering wheel is fitted. b2, and a male screw portion b3 to which a nut for fixing the steering wheel is screwed to the serration portion b2.

[0004] The engaging member c is a small diameter portion b of the shaft body b.
A pair of long holes c1 which are fixed to a large diameter portion b4 having a diameter relatively larger than 1 and extend along the axial direction of the shaft body b are provided at positions facing each other.

FIGS. 10 and 11 show Japanese Patent Application Laid-Open No. 60-4215.
FIG. 10 is a perspective view showing another example of a conventional product, and FIG.
3 is a sectional view taken along line YY of FIG.

As shown in FIGS. 10 and 11, the steering shaft A is made of a hollow material B having a circular cross section. A steering wheel is mounted on one end of the steering shaft A whose diameter is reduced by tube reduction such as extrusion. Serration portion B1 and a male screw portion B2 to which a steering wheel fixing nut is screwed are formed, and a universal joint yoke B3 is formed at the other end.

The steering shaft A is provided at a predetermined portion of a large diameter portion B4 having a diameter relatively larger than one end portion.
A pair of elongated holes B5 that restrict rotation of the steering shaft A by engaging with a lock member (not shown) are provided so as to face each other.

The two steering shafts a,
In A, when the vehicle is parked and the driving key is pulled out, the lock member d driven by the operation of the driving key engages with the long holes c1 and B5 of the steering shaft a and A, and the steering shaft a , A rotation is restricted,
Vehicle theft is prevented.

[0009]

FIGS. 8 and 9 show an embodiment of the present invention.
Is provided with a shaft body b and an engaging member c separately from each other, so that the weight of the steering shaft a becomes large and is not suitable for reducing the weight of the vehicle, and the number of parts is large. However, there is a problem that the productivity is low and the cost is high because welding is performed.

In the steering shaft A shown in FIGS. 10 and 11, a hollow material B as a material must have a large outer diameter, and the long hole B5 reduces the rigidity of the large diameter portion B4. In order to compensate for this, there is a problem that the thickness of the hollow member B needs to be increased, which increases the cost, further increases the weight of the steering shaft A, and reduces the lightening effect by using the hollow member.

Accordingly, an object of the present invention is to provide a steering shaft and a method for manufacturing the same, which are lighter in weight and lower in manufacturing cost than conventional products.

[0012]

According to a first aspect of the present invention, there is provided a steering shaft whose rotation is restricted by engagement with a lock member for preventing the vehicle from being stolen. A large-diameter portion is formed at a predetermined portion of the hollow material by a pipe-expanding process, and a bottomed concave portion is formed on an outer peripheral surface side of the large-diameter portion to engage with the lock member. Is adopted.

Therefore, according to the first aspect of the present invention, it is not necessary to provide an engaging member for engaging with the lock member separately from the hollow member, and therefore, the engaging member is separate from the hollow shaft member. The weight of the steering shaft can be reduced as compared with the conventional product shown in FIG. 8 in which the member is provided on the shaft main body.

According to the first aspect of the present invention, the engaging portion engaging with the lock member is a bottomed recess having a bottom, and the material is continuous in the circumferential direction of the hollow material. Compared with the conventional product shown in FIG. 10 which is a long hole, the rigidity of the portion having the engagement portion in the hollow material is large, and therefore, the engagement strength with the lock member for preventing vehicle theft can be improved, and The thickness of the hollow member can be reduced, and the weight of the steering shaft can be reduced.

According to the first aspect of the present invention, since the large-diameter portion enlarged by the pipe-expanding process is formed at a predetermined portion of the hollow material, the outer diameter of the hollow material excluding the large-diameter portion is large. The diameter is smaller than the outer diameter of the part.

Therefore, according to the first aspect of the present invention, when a small-diameter portion is formed in a hollow material by a contraction process in order to provide a serration portion or a thread portion for mounting a steering wheel, the hollow material has a smaller diameter portion than the large-diameter portion. A small-diameter portion can be subjected to a contraction process such as an extrusion process.

On the other hand, in the conventional product shown in FIG. 10, when a small-diameter portion is formed in a hollow material by a tube-shrinking process, it is necessary to perform the tube-shrinking process on a hollow material having the same diameter as the large-diameter portion. is there.

Therefore, according to the first aspect of the present invention, when a small-diameter portion is formed in a hollow material by a contraction process, the workability of the contraction process for the hollow material is reduced as compared with the conventional product shown in FIG. The manufacturing cost of the steering shaft can be reduced.

According to a second aspect of the present invention, in the steering shaft according to the first aspect, the pipe expanding is performed by disposing the hollow member in a cavity having a predetermined shape formed inside a mold. It is a hydraulic bulging process in which a hollow material is formed into the shape of the hollow portion by press-fitting a high-pressure liquid into the inside.

According to the second aspect of the present invention, the large-diameter portion of the hollow material is work-hardened by hydraulic bulging, and the large-diameter portion has improved strength as compared with the hollow material before processing. Therefore, in the invention of claim 2, in the invention of claim 1, it is possible to further improve the strength of engagement with the lock member for preventing vehicle theft.

According to a third aspect of the present invention, there is provided the steering shaft according to the first or second aspect, wherein the bottomed concave portion is formed by a hollow material extending between both rising surfaces of the large diameter portion rising from the outer peripheral surface of the hollow material. It is characterized by a through groove penetrating along the axis.

According to the third aspect of the present invention, the flow of the material in the bottomed concave portion and the large diameter portion is continuous in the circumferential direction and the axial direction, and the height of both sides of the bottomed concave portion is increased. As a result, the allowance for engagement with the lock member for preventing vehicle theft can be increased, and therefore, the strength of engagement with the lock member can be further improved.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a steering shaft whose rotation is restricted by engagement with a lock member for preventing theft of a vehicle. By expanding the diameter of the portion, a first step of forming a large-diameter portion at the predetermined portion, and pressing the large-diameter portion from the outer peripheral surface side of the large-diameter portion to engage the lock member. And a second step of forming a bottomed concave portion that fits in the large diameter portion.

According to the fourth aspect of the present invention, there is no need to provide an engaging member for engaging with the lock member separately from the hollow member, and the engaging member separate from the hollow shaft member is used. Compared to the conventional manufacturing method of sticking to the shaft body,
The weight of the steering shaft can be reduced.

According to the fourth aspect of the present invention, since the bottomed concave portion is formed in the hollow material as the engaging portion for engaging with the lock member, the engaging portion is formed in a state where the material is continuous in the circumferential direction of the hollow material. In comparison with the conventional manufacturing method in which a hole is formed in a hollow material as the engaging portion, the rigidity of the portion having the engaging portion in the hollow material is high, and thus the thickness of the hollow material is reduced. The weight of the steering shaft can be reduced.

According to the fourth aspect of the present invention, the large-diameter portion is formed at the predetermined portion by subjecting the hollow material to pipe expansion to expand the diameter of the predetermined portion of the hollow material. The diameter of the hollow material excluding is smaller than the diameter of the large diameter portion.

According to the fourth aspect of the present invention, when a small-diameter portion is formed in a hollow material by a contraction process to provide a serration portion or a thread portion for mounting a steering wheel, the hollow material has a larger diameter portion. A small-diameter portion can be subjected to a contraction process such as an extrusion process.

On the other hand, in the conventional product shown in FIG. 10, a hollow material having the same diameter as the large-diameter portion is subjected to a contraction process so that a serration portion for mounting a steering wheel, a screw portion, and the like are formed. The small diameter part for providing is formed in a hollow material.

Therefore, according to the fourth aspect of the present invention, when a small-diameter portion is formed at the end portion of the steering shaft by a tube-contraction process, a conventional hollow member having the same diameter as the large-diameter portion is subjected to the tube-contraction process. Compared with the method, the degree of reduction of the tube in the hollow material can be reduced, and the manufacturing cost of the steering shaft can be reduced.

According to a fifth aspect of the present invention, there is provided a method of manufacturing a steering shaft according to the fourth aspect, wherein the pipe expansion is performed by:
Hydraulic bulging to form the hollow material into the shape of the hollow portion by disposing the hollow material in a hollow portion having a predetermined shape formed inside the molding die and forcing a high-pressure liquid into the hollow material. It is characterized by being.

According to the fifth aspect of the present invention, the large-diameter portion of the hollow material is work-hardened by the hydraulic bulging, and the strength of the large-diameter portion is improved as compared to before the hydraulic bulging. Therefore, in the invention of claim 5, in the invention of claim 4, the thickness of the hollow member can be further reduced, and the weight of the steering shaft can be further reduced.

According to a sixth aspect of the present invention, there is provided the method of manufacturing a steering shaft according to the fourth or fifth aspect, wherein the pressing is performed on one of the rising surfaces of the large diameter portion rising from the outer peripheral surface of the hollow material. By pressing the rollers and moving relative to each other along the axis of the hollow member, a roller forming process is performed in which the bottomed recess penetrating from the one upright surface to the other upright surface is pressed into the large-diameter portion by the forming roller. It is characterized by having.

According to the sixth aspect of the present invention, since the hollow material is moved along the axis of the hollow material, a part of the large diameter portion is pressed and formed by the forming roller. The molding load can be reduced as compared with the case of the indentation molding, and the recess with the bottom can be formed only by moving the hollow material in the axial direction with respect to the molding roller, so that the continuous molding is possible. Yes, good productivity.

Therefore, in the invention of claim 6, in the invention of claim 4 or 5, the labor for pressing the hollow material can be reduced, and the manufacturing cost of the steering shaft can be reduced.

According to a seventh aspect of the present invention, there is provided the method of manufacturing a steering shaft according to the sixth aspect, wherein the roller forming process includes the steps of forming both sides of the bottomed concave portion, the side surfaces and the outer peripheral surface of the large diameter portion. And a second forming roller forming a bottom surface between the two side surfaces after the first forming. It is assumed that.

According to the seventh aspect of the present invention, both sides of the bottomed concave portion and the step formed by the side surface and the outer peripheral surface of the large-diameter portion are formed by the primary processing by the first forming roller. The bottom surface is formed between both side surfaces of the bottomed recess by the secondary processing by the two forming rollers, and the bottomed recess is completed.

Therefore, according to the seventh aspect of the present invention, the primary and secondary
The molding load can be reduced by reducing the amount of deformation of the hollow material that occurs during each of the following processes, and there is no need to use a reinforcing core or the like to reinforce the hollow material when pressing the hollow material. Is easy to press.

According to the seventh aspect of the present invention, since both side surfaces of the bottomed concave portion and the step are formed first, it is possible to reduce the sag of the step caused by the step being drawn in the pressing direction during the pressing. As a result, the margin for engagement with the lock member for preventing vehicle theft can be increased, and the engagement strength with the lock member can be increased.

According to an eighth aspect of the present invention, there is provided a method of manufacturing a steering shaft according to the seventh aspect, wherein the first machining and the second machining are performed.
The next processing is performed continuously.

Therefore, according to the invention of claim 8, according to claim 7,
According to the invention, the productivity of the roller forming process for the hollow material is improved, and the manufacturing cost of the steering shaft can be further reduced.

[0041]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a plan view showing an example of an embodiment in which the inventions of claims 1 to 3 are combined, and FIG. 2 is a partial sectional view of the embodiment shown in FIG. FIG. 3 is a sectional view taken along line XX of FIG.

As shown in FIGS. 1 to 3, the steering shaft 1 has its rotation restricted by engagement with a lock member 2 for preventing vehicle theft, and is formed of a steel hollow having a circular cross section. A small-diameter portion 20 formed by reducing the diameter of the hollow material 10 by a tube-forming process such as rotary swaging or extrusion molding at one end is formed at a predetermined portion near the small-diameter portion 20. A large diameter portion 30 is formed by expanding the hollow material 10 by hydraulic bulging.

The small-diameter portion 20 is formed at its end with a male screw portion 21 to which a nut for fixing a steering wheel is screwed. A serration portion 22 that fits with the boss is formed, and a large-diameter portion 30 is formed with a pair of bottomed concave portions 40 that are through grooves that engage with the lock member 2 at positions facing each other.

The two bottomed recesses 40 are formed on the outer peripheral surface 1 of the hollow material 10.
The hollow material 10 is provided between the two rising surfaces 32 of the large diameter portion 30 which gradually rises from the first rising direction toward the outer peripheral surface 31 of the large diameter portion 30.
A flat bottom surface 41 penetrating along the axis of the hollow member 10 and in contact with the outer peripheral surface 11 of the hollow member 10, and two side surfaces 42 standing vertically from both ends in the width direction of the bottom surface 41 and extending along the axis of the hollow member 10. In addition to the two corner portions 43 located at the boundary, the step portion 44 is provided at the boundary between the both side surfaces 42 and the outer peripheral surface 31 of the large diameter portion 30, and each of the corner portions 43 and the step portion 44 has a small curvature and a sharp shape. It is molded into.

By the way, in the conventional product shown in FIGS. 8 and 9,
Engaging member c having elongated hole c1 engaged with locking member d
And a shaft body b, which is a hollow material, are provided separately,
While the engaging member c is fixed to the shaft body b by welding, the steering shaft 1 has the locking member 2
The large diameter portion 30 having the bottomed concave portion 40 engaging with the hollow material 1
0. Therefore, the weight of the steering shaft 1 can be reduced as compared with the conventional product shown in FIGS.

In the steering shaft 1, the engaging portion that engages with the lock member 2 is the bottomed concave portion 40 having the bottom portion 41, and the material is continuous in the circumferential direction of the hollow member 10. As compared with the conventional product shown in FIG. 10 in which the portion is the elongated hole B5, the rigidity of the portion having the engaging portion in the hollow member 10 is larger, and therefore, the engaging strength with the lock member 2 for preventing vehicle theft is increased. Can also be hollow material 1
0 can be made thinner and lighter.

Further, in the steering shaft 1, the large-diameter portion 30 of the hollow member 10 is work-hardened by hydraulic bulging, and the large-diameter portion 30 having the bottomed concave portion 40 to be engaged with the lock member 2 The strength is improved as compared with the hollow member 10. Therefore, the strength of the portion of the hollow member 10 that engages with the lock member 2 is improved by work hardening.
0 As compared with the conventional product shown in the figure, the engagement strength with the lock member 2 can be increased, and the thickness of the hollow member 10 can be reduced, so that the weight of the steering shaft 1 can be reduced. .

By the way, in the steering shaft 1,
Since the large-diameter portion 30 whose diameter is increased by hydraulic bulging is formed at a predetermined portion of the hollow member 10, the large-diameter portion 30 is formed.
The outer diameter of the hollow member 10 except for the outer diameter is smaller than the outer diameter of the large diameter portion 30.

Therefore, in the steering shaft 1,
When a small-diameter portion 20 is formed in the hollow material 10 by contraction processing to provide a serration portion 22 and a screw portion 21 for mounting a steering wheel, the hollow material 10 is extruded to a portion having a smaller diameter than the large-diameter portion 30. The tube can be subjected to a contraction process such as a process.

On the other hand, in the conventional product shown in FIG. 10, when a small-diameter portion is formed in the hollow material B by the contraction process, the hollow material B having the same diameter as the large-diameter portion B4 is subjected to the contraction process. Need to be applied. Therefore, in the steering shaft 1, FIG.
In comparison with the conventional product shown in FIG. 0, the degree of working of the hollow tube 10 in the contraction can be reduced, and as a result, the manufacturing cost of the steering shaft 1 can be reduced.

Further, in the steering shaft 1, the bottomed concave portion 40 forms a hollow material 10 between the two rising surfaces 32 of the large diameter portion 30.
, The flow of the material of the bottomed recess 40 and the large diameter portion 30 is continuous in the circumferential direction and the axial direction, and the height of both side surfaces 42 of the bottomed recess 40 Can be increased to increase the margin for engagement with the lock member 2 for preventing vehicle theft, and therefore, the engagement strength with the lock member 2 can be further increased.

FIGS. 4 to 7 show an example of an embodiment in which the inventions of claims 4 to 8 are implemented together. FIG.
FIG. 5 is an explanatory view showing a first step of a method of manufacturing the steering shaft 1, and FIG. 5 is a cross-sectional view showing a processing state of a material in the first step; ,
(B) shows the state after processing.

As shown in FIGS. 4 and 5, in the manufacture of the steering shaft 1, in the first step, the hollow material 10, which is the material of the steering shaft 1, is subjected to hydraulic bulging to thereby form the hollow material 10. The large diameter portion 30 is formed at a predetermined position.

The hydraulic bulging apparatus 50 used in the first step includes a dividable frame 51, a dividable mold 53 housed in the frame 51 and having a cavity 52 of a predetermined shape, Punches 54 and 55 are inserted into both ends of the portion 52, and a cylinder device 56 that presses each of the punches 54 and 55 into the hollow portion 52.

The hollow portion 52 of the molding die 53 has a same-diameter portion 52a having the same inner diameter as the outer diameter of the hollow material 10 as a material.
And a large-diameter portion 52 b having an inner diameter larger than the outer diameter of the hollow material 10. The large-diameter portion 52 b is formed at a predetermined position of the molding die 53.

One punch 54 has a liquid supply hole 54a for supplying a high-pressure liquid such as water or oil inside the hollow member 10 accommodated in the hollow portion 52 of the molding die 53. The liquid supply hole 54a
The transporting pipe 57 for the liquid is piped to the other, the other punch 55 has a deaeration hole 55a for venting air, and a valve 59 is connected to the deaeration pipe 58 piped to the deaeration hole 55a. .

In the hydraulic bulging process, first, the hollow material 10 is housed in the hollow portion 52 of the mold 53, and the punches 54 and 55 are inserted into both ends of the hollow portion 52, so that the hollow material is placed at a predetermined position in the hollow portion 52. The material 10 is set. Thereafter, the cylinder device 56
While applying a predetermined compressive force to the hollow material 10 in the axial direction of the hollow material 10, a high-pressure liquid is pressed into the hollow material 10, and the hollow material 10 is formed into the shape of the hollow portion 52. A large-diameter portion 30 is formed at a predetermined portion 10. The large diameter portion 3 of the hollow member 10 formed by the hydraulic bulging process
In the case of No. 0, the strength is improved by work hardening as compared to before the work.

FIG. 6 is an explanatory diagram showing a second step of the method of manufacturing the steering shaft 1. FIGS. 7A and 7B are cross-sectional views showing the state of forming the material in the second step, wherein FIG. 7A shows the state of the first processing by the first forming roller, and FIG.
The state of the 2nd process by a forming roller is shown.

As shown in FIGS. 6 and 7, in the manufacture of the steering shaft 1, the hollow member 1
By pressing the large-diameter portion 30 from the outer peripheral surface 31 side of the large-diameter portion 30, the locking member 2 for preventing vehicle theft is provided.
The large-diameter portion 30 is formed with a bottomed concave portion 40 that engages with.

The pressing device 6 used in the second step
0 denotes a hollow portion 61 having a circular cross section having an inner diameter substantially the same as the outer diameter of the large diameter portion 30 of the hollow material 10, and pushing the hollow material 10 in the pushing direction P along the axis of the hollow portion 61. Pushing force F to advance
(Not shown) such as a cylinder device for applying the pressure to the hollow material 10 via the punch 62, and the large-diameter portion 3 of the hollow material 10.
A pair of rotatable first forming rollers 63 for forming two grooves at intervals corresponding to the width of the bottomed concave portion 40 to form the side surfaces 42 and the step portion 44 at 0. A pair of rotatable second forming rollers 64 that are arranged in series and form the bottom surface 41 of the bottomed concave portion 40 and the two corner portions 43 are provided.

The first forming rollers 63 are disposed to face each other and a part of them protrudes into the hollow portion 61, and the second forming rollers 64 move in the pushing direction P of the hollow material 10 from the first forming roller 63. The first and second forming rollers 6 are disposed so as to face each other on the downstream side and partially project into the hollow portion 61.
3, 64, the projecting length of the hollow portion 61 is set to the height from the outer peripheral surface 11 of the hollow member 10 to the outer peripheral surface 31 of the large diameter portion 30.

The first forming rollers 63 have the same width as the width of the finally formed bottomed concave portion 40. The outer peripheral surface has both ends in the width direction over the entire outer peripheral surface. The outer circumferential projection 63a has an outer surface formed flush with the side surface of the first forming roller 63, and an inner surface formed by the first forming roller from the top of the outer surface. The inclined surface is inclined downward toward the outer peripheral surface of the roller 63. Each second
The forming roller 64 has the same width as the width of the finally formed bottomed concave portion 40, and has a flat outer peripheral surface.

The second operation performed by using the pressing device 60
In the process, the hollow material 10 is inserted into the hollow portion 61 of the pressing device 60.
Is set, and the punch 62 is driven by a pushing device (not shown).
A pushing force F is applied to the hollow material 10 through the
Is gradually moved in the pushing direction P in the hollow portion 61.

As a result of this movement, first, the upright surface 32 on the downstream side in the pushing direction P of the large-diameter portion 30 rising from the outer peripheral surface 11 of the hollow member 10 comes into pressure contact with the first forming roller 63, and from the upright surface 32, The primary processing by the one forming roller 63 is gradually performed on the large-diameter portion 30, and the both side surfaces 42 and the step portion 44 in the bottomed concave portion 40 are pressed and formed. Then, at the time of this indentation molding, since the sag in the indentation direction of the step portion 44 can be reduced, the step portion 44 is formed into a sharp shape with a small curvature.

Subsequently, the hollow material 10 is gradually subjected to secondary processing by the second forming roller 64 on the large-diameter portion 30 after the primary processing, so that the bottom surface 41 of the bottomed concave portion 40 and both corner portions 43 are pushed. Going molded. At this time, the bottom surface 41 is formed so as to be flat and the side surfaces 42 are perpendicular to the bottom surface 41.

Then, both the first and second forming rollers 6
At the point in time when the third and fourth holes 64 pass through the large-diameter portion 30, the large-diameter portion 30 has a bottomed concave portion 40 that penetrates between the upstanding surfaces 32 of the large-diameter portion 30 along the axial direction of the hollow member 10.

In the manufacture of the steering shaft 1, after forming the bottomed concave portion 40 in the large diameter portion 30 of the hollow member 10, as shown in FIG. And forming a small-diameter portion 20 having a diameter smaller than the outer diameter 11 of the hollow member 10 by forming a serration portion 22 that fits with the boss of the steering wheel. Male thread 2 to which nut for fixing steering wheel is screwed
1 are formed.

In the manufacturing method of the steering shaft 1 described above, the large-diameter portion 30 having the bottomed concave portion 40 engaged with the lock member 2 can be integrally formed with the hollow member 10. The engaging member c to be hollow member b
As compared with the conventional manufacturing method shown in FIGS. 8 and 9 in which the steering shaft 1 is provided separately and fixed to the hollow member b, the weight of the steering shaft 1 can be reduced.

In the manufacturing method of the steering shaft 1, the bottomed recess 4 is used as an engagement portion that engages with the lock member 2.
0 is formed in the hollow member 10 so that the engaging portion can be formed in a state where the material is continuous in the circumferential direction of the hollow member 10, and a hole B5 is formed in the hollow member B as the engaging portion.
Compared with the conventional manufacturing method shown in FIG. 0, the rigidity of the hollow material 10 at the portion having the engaging portion is higher, and therefore, the thickness of the hollow material 10 can be reduced, and the weight of the steering shaft 1 can be reduced. It is.

Further, in the method of manufacturing the steering shaft 1, the large diameter portion 30 of the hollow member 10 is hardened by hydraulic bulging, and the bottomed concave portion 40 engaged with the lock member 2 is formed.
The large-diameter portion 30 having the above has improved strength as compared with the hollow member 10 before processing. Therefore, the thickness of the hollow member 10 can be reduced as compared with the conventional manufacturing method also in that the strength of the portion of the hollow member 10 that engages with the lock member 2 is improved by work hardening. Weight reduction becomes possible.

In the manufacturing method of the steering shaft 1, the hollow member 10 is subjected to a pipe expanding process to expand a predetermined portion of the hollow member 10, thereby forming the large-diameter portion 30 at the predetermined portion. Hollow material 10 excluding large diameter portion 30
Is smaller than the diameter of the large diameter portion 30.

For this reason, in the manufacturing method of the steering shaft 1, when the small diameter portion 20 is formed in the hollow material 10 by the contraction processing to provide the serration portion 22 and the screw portion 21 for mounting the steering wheel, the hollow material is used. A portion having a smaller diameter than the large-diameter portion 30 in 10 can be subjected to a tube reduction process such as an extrusion process.

On the other hand, in the conventional product shown in FIG. 10, the hollow material B having the same diameter as the large-diameter portion B4 is subjected to a contraction process so that the serration portion B1 for mounting the steering wheel and the screw are formed. A small diameter portion for providing the B2 portion and the like is formed in the hollow material B.

Therefore, in the manufacturing method of the steering shaft 1, when the small diameter portion 20 is formed at the end of the steering shaft 1 by the contraction processing, the hollow material B having the same diameter as the large diameter portion B4 is subjected to the contraction processing. Compared to the conventional manufacturing method
The manufacturing cost of the steering shaft 1 can be reduced by reducing the degree of reduction of the hollow tube 10 in the tube forming process.

In the method of manufacturing the steering shaft 1, the first and second forming rollers 63 and 64 are relatively moved along the axis of the hollow member 10 so that the bottomed concave portion 40 is formed in a part of the large diameter portion 30. In this case, the forming load can be reduced as compared with the case where the recess 40 with the bottom is pushed toward the axis of the hollow member 10, and the hollow member 10 is applied to both forming rollers 63 and 64. The bottomed concave portion 40 can be formed only by moving in the axial direction, which facilitates processing.

Accordingly, compared with the case where the bottomed concave portion 40 is pressed toward the axis of the hollow member 10, the bottomed concave portion 40 is formed.
The manufacturing cost of the steering shaft 1 can also be reduced by reducing the labor required for molding.

In the method of manufacturing the steering shaft 1, the first forming roller 63 performs the primary processing to form the stepped portion formed by the side surfaces 42 of the bottomed recess 40 and the side surface 42 and the outer peripheral surface 31 of the large diameter portion 30. In order to form the step 4, the step 4 is generated by the step 44 being drawn in the pressing direction during the pressing process.
4 can be reduced, and as a result, the margin of engagement with the lock member 2 for preventing vehicle theft in the bottomed recess 40 can be increased, and the engagement strength with the lock member 2 can be increased. it can.

Also, since the bottom surface 41 is formed flat between the both side surfaces 42 of the bottomed concave portion 40 by the secondary processing by the second forming roller 64 and the both side surfaces 42 are perpendicular to the bottom surface 41, The amount of deformation of the hollow material 10 generated during each of the following processing and the secondary processing can be reduced to reduce the forming load, and a reinforcing core or the like for reinforcing the hollow material 10 at the time of pressing the hollow material 10 is used. There is no need, and the pressing of the hollow material 10 is easy.

Therefore, in the manufacturing method of the steering shaft 1, the productivity of the steering shaft 1 can be improved and the manufacturing cost of the steering shaft 1 can be reduced.

Further, in the manufacturing method of the steering shaft 1, the primary processing by the first forming roller 63 and the secondary processing by the second forming roller 64 are continuously performed, so that the productivity of the roller forming processing for the hollow member 10 is improved. And the manufacturing cost of the steering shaft 1 can be further reduced.

In the above-described embodiment of the present invention, the large-diameter portion 30 is formed in the hollow member 10 in one step.
The large-diameter portion 30 may be formed in multiple stages, and when the large-diameter portion 30 is formed in multiple stages, the outer diameter of the hollow member 10 can be further reduced.

[0082]

According to the first aspect of the present invention, it is not necessary to provide an engaging member for engaging with the lock member separately from the hollow member, so that the shaft main body and the engaging member are provided separately.
The weight of the steering shaft can be reduced as compared with the conventional product shown in the figure.

According to the first aspect of the present invention, the engaging portion engaging with the lock member is a bottomed recess having a bottom, and the material is continuous in the circumferential direction of the hollow member. Compared with the conventional product shown in FIG. 10 which is a hole, the rigidity of the portion having the engaging portion in the hollow material is higher, and the strength of engagement with the lock member for preventing vehicle theft can be improved. Therefore, the thickness of the hollow member can be reduced, and the weight of the steering shaft can be reduced.

Further, according to the first aspect of the present invention, when a small-diameter portion is formed in a hollow material by a contraction process, a portion of the hollow material having a smaller diameter than a large-diameter portion can be subjected to the contraction process. FIG. 10 shows a process in which a portion having the same diameter as the large-diameter portion is subjected to contraction.
Compared with the conventional product shown in the figure, the degree of reduction of the tube in the hollow material can be reduced, and the manufacturing cost of the steering shaft can be reduced.

According to the second aspect of the present invention, the large-diameter portion of the hollow material is work-hardened by hydraulic bulging, and the large-diameter portion has improved strength as compared with the hollow material before processing. The strength can be further improved, and in the invention of claim 1, the thickness of the hollow member can be further reduced, and the weight of the steering shaft can be further reduced.

According to the third aspect of the present invention, the flow of the material in the bottomed concave portion and the large diameter portion is continuous in the circumferential direction and the axial direction, and the height of both side surfaces of the bottomed concave portion is increased so that the vehicle is stolen. Since the margin for engagement with the lock member for prevention can be increased, the strength of engagement with the lock member can be further improved.

According to the fourth aspect of the present invention, there is no need to provide an engaging member for engaging with the lock member separately from the hollow member, and the conventional engaging member separate from the shaft main body is fixed to the shaft main body. As compared with the manufacturing method, the weight of the steering shaft can be reduced.

According to the fourth aspect of the present invention, since the bottomed concave portion is formed in the hollow material as the engaging portion for engaging with the lock member, the engaging portion is formed in a state where the material is continuous in the circumferential direction of the hollow material. In comparison with the conventional manufacturing method in which a hole is formed in a hollow material as the engaging portion, the rigidity of the portion having the engaging portion in the hollow material is high, and thus the thickness of the hollow material is reduced. The weight of the steering shaft can be reduced.

Further, according to the fourth aspect of the present invention, when a small-diameter portion is formed at the end of the steering shaft by the tube-shrinking process, the conventional hollow tube having the same diameter as the large-diameter portion is subjected to the tube-shrinking process. Compared with the method, the degree of reduction of the tube in the hollow material can be reduced, and the manufacturing cost of the steering shaft can be reduced.

According to the fifth aspect of the present invention, the large-diameter portion of the hollow material is work-hardened by hydraulic bulging, and the strength of the large-diameter portion is improved as compared with before the hydraulic bulging process. In the present invention, the thickness of the hollow member can be further reduced, and the weight of the steering shaft can be further reduced.

According to the sixth aspect of the present invention, the forming load can be reduced as compared with the case where the recessed portion with the bottom is pushed toward the axis of the hollow material, and the hollow material is moved in the axial direction with respect to the forming roller. Since the bottomed concave portion can be formed only by moving, continuous molding is possible and productivity is high. Therefore, it is possible to reduce the time and effort for pressing the hollow material and reduce the manufacturing cost of the steering shaft.

According to the seventh aspect of the present invention, since the amount of deformation of the hollow material generated during the primary and secondary workings can be reduced to reduce the forming load, the hollow material is reinforced at the time of pressing the hollow material. There is no need to use a reinforcing core or the like, the pressing of the hollow material is easy, and the manufacturing cost of the steering shaft can be reduced.

According to the seventh aspect of the present invention, since the both sides of the bottomed concave portion and the step are formed first, it is possible to reduce the sag of the step caused by the step being drawn in the pressing direction during the pressing. As a result, the engagement allowance with the lock member for preventing vehicle theft can be increased, and the engagement strength with the lock member can be increased.

According to the eighth aspect of the present invention, one of the roller forming processes is performed.
Since the secondary processing and the secondary processing are performed continuously, in the invention of claim 7, the productivity of the roller forming processing on the hollow material is improved, and the manufacturing cost of the steering shaft can be further reduced.

[Brief description of the drawings]

FIG. 1 is a plan view showing an example of an embodiment of a steering shaft according to the present invention.

FIG. 2 is a front view showing a part of FIG. 1 in a partial cross section.

FIG. 3 is a sectional view taken along line ZZ of FIG.

FIG. 4 is an explanatory view showing a cross section of a first step of a method of manufacturing the device shown in FIG.

5A and 5B are cross-sectional views showing a processing state of the one shown in FIG. 4, wherein FIG. 5A shows a state before processing and FIG. 5B shows a state after processing.

FIG. 6 is an explanatory view showing a second step of the manufacturing method of the device shown in FIG. 1 in cross section.

7A and 7B are cross-sectional views showing a processing state of the one shown in FIG. 6, wherein FIG. 7A shows a state of primary processing and FIG. 7B shows a state of secondary processing.

FIG. 8 is a front view showing an example of a conventional product in a partial cross section.

FIG. 9 is a sectional view taken along line XX of FIG.

FIG. 10 is a perspective view showing another example of a conventional product.

FIG. 11 is a sectional view taken along line YY of FIG.

[Explanation of symbols]

 Reference Signs List 1 steering shaft 2 lock member 10 hollow member 11 outer peripheral surface of hollow member 30 large-diameter portion 31 outer peripheral surface of large-diameter portion 32 rising surface of large-diameter portion 40 bottomed concave portion 41 bottom surface of bottomed concave portion 42 side surface of bottomed concave portion 44 Stepped portion of bottomed concave portion 53 Mold 52 Mold cavity 63 First forming roller 64 Second forming roller

Claims (8)

[Claims] 1. A steering shaft whose rotation is restricted by engagement with a lock member for preventing vehicle theft, comprising a hollow material, and a predetermined portion of the hollow material having a large diameter expanded by a pipe expanding process. A steering shaft, wherein a diameter portion is formed, and a bottomed concave portion which engages with the lock member is formed on an outer peripheral surface side of the large diameter portion. 2. The steering shaft according to claim 1, wherein in the pipe expansion, the hollow material is disposed in a cavity having a predetermined shape formed inside a mold, and a high-pressure liquid is provided in the hollow material. A hydraulic bulging process for forming a hollow material into the shape of the hollow portion by press-fitting. 3. The steering shaft according to claim 1, wherein the bottomed recess penetrates between two rising surfaces of the large diameter portion rising from an outer peripheral surface of the hollow material along an axis of the hollow material. A steering shaft having a through groove. 4. A method of manufacturing a steering shaft whose rotation is restrained by engagement with a vehicle anti-theft locking member, wherein the hollow member is subjected to a pipe expanding process to expand a predetermined portion of the hollow member. Thereby, a first step of forming a large-diameter portion in the predetermined portion, and a pressing process from an outer peripheral surface side of the large-diameter portion to the large-diameter portion to engage with the locking member. And a second process of forming the steering shaft in the large diameter portion. 5. The method of manufacturing a steering shaft according to claim 4, wherein, in the pipe expanding process, the hollow material is disposed in a hollow portion having a predetermined shape formed inside a mold, and the hollow material is provided inside the hollow material. A method of manufacturing a steering shaft, comprising a hydraulic bulging process for forming a hollow material into the shape of the hollow portion by press-fitting a high-pressure liquid. 6. The method of manufacturing a steering shaft according to claim 4, wherein the pressing is performed by pressing a forming roller against one of the rising surfaces of the large-diameter portion rising from the outer peripheral surface of the hollow member. By relatively moving along the axis of the material, it is a roller forming process in which the bottomed recess penetrating from the one upright surface to the other upright surface is pressed into the large diameter portion by the forming roller. Of manufacturing a steering shaft. 7. The manufacturing method of a steering shaft according to claim 6, wherein the roller forming process includes forming both side surfaces of the bottomed concave portion and a step formed by the side surface and the outer peripheral surface of the large diameter portion. And a second forming roller for forming a bottom surface between the two side surfaces after the first forming. Production method. 8. The method for manufacturing a steering shaft according to claim 7, wherein the primary processing and the secondary processing are performed continuously.