JPH08174127A - Device for manufacturing rack shaft - Google Patents

Abstract

PURPOSE: To control the bend of a form-rolling roll, to miniaturize a device and also to improve working efficiency and accuracy of rack teeth at the time of forming rack teeth by form rolling on the side faces of a base stock for a hollow rack shaft by providing a backup supporting means to the form-rolling roll. CONSTITUTION: This device 20 has a base stock clamping device for holding a core bar 26 in the state where the core bar is inserted into the hollow part of the base stock 11 for rack shafts like a hollow pipe and a form-rolling roll moving device (sliding device) 24 for moving the form-rolling roll 27 on the peripheral surface of which rack tooth forms are formed and which is rotatably supported along the base stock 11 for rack shafts, the base stock clamping device 23 and the form-rolling roll 27 are relatively slid in the tangent direction of the form-rolling roll. The backup supporting device 10 for backing up and supporting the form-rolling roll 27 to the roll axial center of this form-rolling roll 27 is provided on the opposite side of a side where the base stock 11 for rack shafts is situated. In this way, the bend of the form-rolling roll is detered at the time of forming the rack tooth forms.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rack shaft manufacturing method for rolling rack teeth on a side surface of a rack shaft material.

[0002]

2. Description of the Related Art Generally, a rack shaft used in an automobile steering mechanism or the like is one in which a part of the peripheral surface of a round bar is made flat and rack teeth are formed therein.

As a method of forming rack teeth on a rack shaft material by plastic working, Japanese Patent Publication No. 58-31257 discloses that a rack tooth forming portion of the material is an upper die provided with a rack tooth profile and is perpendicular to the axis line of the material. A method of pressing in the direction is shown.

Further, Japanese Patent Publication No. 3-5892 discloses a molding die in which an uneven surface corresponding to a rack tooth is formed on a flat surface of a rack shaft material made of a hollow pipe having a tooth row forming portion as a flat surface. There is shown a method in which a tooth is formed by pressing the punch into the hollow pipe by pressing it into the concave-convex surface of the molding die.

However, in all of the above conventional techniques, there is a step of forming a flat portion on the side surface of the hollow pipe in advance, and a large processing force (pressing force) is required. Easy to burr.

Therefore, the applicant of the present invention has proposed a method for manufacturing a rack shaft, which is capable of forming rack teeth with a relatively small force and has little burr, according to Japanese Patent Application No. 5-299091. This prior art technology states that "when manufacturing a rack shaft having rack teeth on its side surface, a hollow pipe-shaped rack shaft material is held with a mandrel inserted therein, and a rack tooth profile is formed on the peripheral surface. A manufacturing roll is rotatably held along the rack shaft material, and the rack shaft material and the rolling roll are slid relative to each other in the tangential direction of the rolling roll to form rack teeth on the rack shaft material. "Rolling".

[0007]

However, the above-mentioned prior application technique has the following problems. In order to increase the rolling depth per rolling stroke of the rolling roll, it is better to increase the diameter of the rolling roll in order to secure the bending rigidity of the roll shaft of the rolling roll. However, when the diameter of the rolling roll is increased, not only the apparatus becomes large, but also the contact area between the rolling roll and the surface to be processed increases and the rolling pressure decreases, resulting in one rolling roll sliding. The swelling of the processed part per process is reduced and the processing time is lengthened.

If the diameter of the rolling roll is reduced in order to eliminate the above-mentioned inconvenience, the roll shaft of the rolling roll bends due to the rolling pressure, and the shape accuracy of the rolling rack teeth decreases.

That is, since the rolling pressure acts so as to bend the roll shaft of the rolling roll, the shape of the rack teeth tends to be different between the central portion and the left and right end portions in the rack axial direction. If the tooth profiles at both the left and right ends are properly formed, the swelling of the tooth profile at the center will be insufficient. On the contrary, if the center tooth profile is properly formed, the amount of material deformation at both left and right ends becomes excessive, and the amount of bulging in the pipe circumferential direction due to the presence of the toothed cores at both left and right ends becomes large. Become.

An object of the present invention is to reduce the size of an apparatus in a method for manufacturing a rack shaft, improve the processing efficiency, and improve the shape accuracy of a rolled rack tooth.

[0011]

According to a first aspect of the present invention, in a rack shaft manufacturing apparatus for manufacturing a rack shaft having rack teeth on a side surface thereof, a hollow pipe-shaped rack shaft material is provided in its hollow portion with a core bar. A material holding means for holding the inserted material in a state of being inserted, a rolling roll having a rack tooth shape formed on the peripheral surface thereof and rotatably supported along the rack shaft material, the material holding means and the rolling roll. With respect to the sliding means for relatively sliding in the tangential direction of the rolling roll and the roll shaft center of the rolling roll, which is on the side opposite to the side where the rack shaft material is located, the rolling roll is backed up and supported. And a backup support means.

The present invention according to claim 2 is the same as the invention according to claim 1, further comprising: a feed means for adjusting an axial distance between the rack shaft material held by the material holding means and the rolling roll. It is equipped with.

[0013]

According to the present invention as set forth in claim 1, the following effects are obtained. By sliding the rack shaft material and the rolling roll relatively in the tangential direction of the rolling roll by the sliding means, the rack teeth can be rolled on the rack shaft material. At this time, the rolling roll comes into pressure contact with the rack shaft material, but since the rack shaft material slides in the tangential direction relative to the rolling roll, the rolling roll rotates by the tangential force while biting into the rack shaft material. Then
Roll the rack teeth on the rack shaft material.

When the rolling pressure acts to bend the roll shaft of the rolling roll, the backup supporting means can prevent the bending deformation of the roll shaft of the rolling roll. Therefore, it is not necessary to increase the diameter of the rolling roll in order to secure the bending rigidity of the roll shaft of the rolling roll, and the device can be downsized.

According to the above, even if the diameter of the rolling roll is reduced, the roll shaft of the rolling roll is difficult to bend, and as a result, the rolling rack teeth are not deteriorated in processing accuracy and the rolling pressure can be increased.

As described above, since the diameter of the rolling roll can be reduced, the contact area between the rolling roll and the surface to be processed is reduced, and the pressure contact force per unit area is increased. It is possible to increase the swelling of the processed part per moving stroke and shorten the processing time.

The present invention according to claim 2 has the following effects. In the above, the rolling roll is provided at every predetermined stroke (for example, every stroke) of the above relative sliding with respect to the rack shaft material,
The distance between the rack shaft material and the rack shaft material can be reduced by the feeding means. As a result, the rolling roll bites into the material little by little at each predetermined stroke of the relative sliding, so that the rack teeth can be formed with a relatively small force without requiring a large force at one time. Further, it is possible to form a rack tooth which is less likely to cause burr on the formed rack tooth and which is excellent in strength by rolling.

[0018]

1 is a front view showing a first embodiment of the present invention, FIG. 2 is a side view of FIG. 1, FIG. 3 is an enlarged view of an essential part of FIG. 2, and FIG. FIG. 5 is a front view showing a second embodiment of the present invention, FIG. 6 is a side view of FIG. 5, FIG. 7 is a schematic view showing a backup supporting means, and FIG. 8 is a schematic view showing a mandrel. 9 is a perspective view showing a rack shaft.

(First Embodiment) (FIGS. 1 to 4 and 7 to 9) As shown in FIG. 9, the rack shaft 10 is a part of the peripheral surface of a rack shaft material 11 made of a hollow round pipe. A certain flat side surface has a large number of rack teeth 12 which intersect in the axial direction.

The rack shaft manufacturing apparatus 20 includes a frame 21, a material clamping device 22 (material holding means), a core metal setting device 23, a rolling roll moving device 24 (sliding means), and a rolling depth adjustment. The device 25 (feeding device) and the backup support device 110 (backup support device) are provided, and the rack shaft material 11 and the rolling roll 27 are rolled in a state in which the mandrel 26 is inserted into the rack shaft material 11. The rack shaft material 11 is slid relative to the tangential direction of the roll 27 and the rack teeth 12
Is to be rolled.

The configuration of each part of the rack shaft manufacturing apparatus 20 will be described below. (A) Stand 21 (FIGS. 1 and 2) The stand 21 supports a top plate 32 via columns 31 at four corners.

(B) Material Clamping Device 22 (FIGS. 1 to 4) The material clamping device 22 has a recess 43 in the clamp holder 42 guided by a clamp holder guide 41 fixed to the left and right front and rear columns 31, 31. , The clamp members 44 and 45 which are divided into two parts on the left and right are arranged.
The rack shaft blank 11 is held between 45.

The left and right clamp members 44 and 45 are arranged in the recess 43 of the clamp holder 42 so as to be movable in the left and right directions. On the other hand, the clamp cam 47 is connected to the rod of the clamp cylinder 46 integrally arranged on the lower surface of the clamp holder 42, and the wedge-shaped cam surface of the clamp cam 47 abuts the lateral contact surface of the left clamp member 44. ing.

As a result, when the clamp cylinder 46 moves up the clamp cam 47, the left clamp member 44 moves to the right and the left and right clamp members 44 and 45 hold the rack shaft material 11 and the rack shaft material 11 moves. Rolling processing can be started. When the rolling process of the rack shaft material 11 is completed, the clamping cylinder 46 moves down the clamping cam 47, and as a result, the spring (not shown) interposed between the left and right clamping members 44 and 45 clamps the left clamp. The member 44 is returned to the original position, and the holding of the rack shaft material 11 by the left and right clamp members 44 and 45 is released.

The left and right clamp members 44 and 45 have a material lower surface clamp portion 48 and a material upper surface clamp portion 49, as shown in FIGS. The material lower surface clamp part 48 is
It is provided over the entire area of the clamp members 44 and 45 in the front-rear direction, and has substantially the same shape as the pipe outer peripheral surface of the rack shaft material 11 so that the lower half surface of the rack shaft material 11 to the upper part of the equatorial surface 11A can be tightened. The material upper surface clamp portion 49 is provided to clamp the rack member 11 in order to secure the holding of the rack shaft material 11.
They are provided at the front and rear end portions of Nos. 4 and 45 and have substantially the same shape as the pipe outer peripheral surface of the rack shaft material 11 so that the upper half surface of the rack shaft material 11 can be tightened. The material lower surface clamp portion 48 and the material upper surface clamp portion 49 of the left clamp member 44 and the material lower surface clamp portion 48 and the material upper surface clamp portion 49 of the right clamp member 45 have a slight gap g (see FIG. 3).
(B)) is left, the rack shaft blank 11 is clamped and held.

In FIG. 4, 50 is a clamp holder 42.
It is a material stopper provided in. The material stopper 50 positions the holding position in the longitudinal direction of the rack shaft material 11 held by the left and right clamp members 44 and 45.

The clamp holder guide 41 and the clamp holder 42, the clamp cam 47 and the clamp holder 4 are provided.
2. The left clamp member 44 and the clamp holder 42 are provided with engaging grooves 51A, 52A, 53A and protrusions 51B, 52, respectively.
It is guided movably in only one direction through engagement with B and 53B.

(C) Mandrel setting device 23 (FIGS. 1 to 4) In the mandrel setting device 23, the mandrel cylinder 6 is mounted on the cylinder bracket 61 provided on the rear surface of the clamp holder 42.
2, the mandrel mounting bracket 63 is fixed to the rod of the mandrel cylinder 62.
The above-mentioned mandrel 26 is attached to 3.
A bracket guide 64 is provided between the cylinder bracket 61 and the clamp holder 42 to guide the mandrel mounting bracket 63.

As a result, when the mandrel cylinder 62 advances the mandrel mounting bracket 63, the mandrel 26 is set at the material insertion position between the left and right clamp members 44 and 45, and is placed inside the pipe of the rack shaft material 11. The mandrel 26 can be inserted to start the rolling process of the rack shaft blank 11. When the rolling process of the rack shaft material 11 is completed, the mandrel cylinder 62 retracts the mandrel mounting bracket 63, so that the mandrel 26 is removed from the inside of the pipe of the rack shaft material 11.

In this embodiment, the mandrel is moved and set to a predetermined position for each processing, but it may be fixed in advance to the predetermined position without any problem.

(D) Rolling roll moving device 24 (FIGS. 1 and 2) The rolling roll moving device 24 includes a pair of left and right roll reciprocating rollers on both sides of a cylinder bracket 71 which is suspended and fixed to the lower surface of the top plate 32. Moving cylinders 72, 72 are provided. A slide bracket 74 on the lower surface of the cylinder bracket 71 guides a slide bracket 74 to the left and right. The slide bracket 74 has a roll holder 75, and the rolling holder 27 is rotatably supported by the roll holder 75.

As a result, the rolling roll 27 is rotatably held along the rack shaft blank 11 held by the left and right clamp members 44 and 45 of the blank clamp device 22 with the rack tooth profile on the peripheral surface. To be done. The rolling roll 27 slides relative to the rack shaft material 11 in the tangential direction of the rolling roll 27 as the slide bracket 74 reciprocates left and right by the operation of the left and right reciprocating cylinders 72, 72. Move.

In this embodiment, the cylinder bracket is fixed to the top plate, but it is also possible to rotatably support the cylinder bracket with respect to the top plate with the center of the cylinder bracket as an axis. According to this, a helical rack shaft having teeth inclined with respect to the rack shaft axis can be formed.

(E) Rolling depth adjusting device 25 (FIGS. 1 and 2) The rolling depth adjusting device 25 moves the rolling depth adjusting cam 82 back and forth by a cam guide 81 provided on the upper surface of the pedestal 21. It is guided to move freely. On the other hand, the lower contact surface of the driven portion 83 protrudingly provided on the lower surface of the clamp holder 42 abuts against the wedge-shaped cam surface of the rolling depth adjusting cam 82. A motor 84 is supported on the gantry 21, and a screw shaft 85 driven by the motor 84 is screwed to the rolling depth adjustment cam 82.

The rolling depth adjusting device 25 rotates the screw shaft 85 by a predetermined angle for each stroke of the reciprocating movement of the rolling roll 27 by the rolling roll moving device 24, and the rolling depth guided by the cam guide 81. The adjustment cam 82 is moved forward by a fixed amount. Every time the rolling depth adjusting cam 82 moves, the clamp holder 42 is guided by the above-mentioned clamp holder guide 41 to move upward. The upward movement of the clamp holder 42 is synchronized with the reciprocating movement of the rolling holder 27, and the rack shaft material 11 and the rolling roll 27 are moved at each sliding stroke of the rolling roll 27 with respect to the rack shaft material 11. The distance between the axes is reduced, and the depth of the rack teeth is gradually increased.

(F) Backup support device 110 (see FIG.
2 and 7) The backup support device 110 is configured to rotatably support the backup roll 111 on the roll holder 75 that rotatably supports the rolling roll 27 as described above (see FIGS. 7 (A)). Backup roll 1
11 is on the opposite side to the side where the rack shaft material 11 is located with respect to the roll shaft center of the rolling roll 27.
The rolling roll 27 is backed up and supported in contact with the surface of the entire body length.

The backup support device 110 is shown in FIG.
As shown in (B), two or more backup rolls 111A, 111 rotatably supported by the roll holder 75.
The rolling roll 27 may be backed up and supported by B.

The backup supporting device 110 may be formed of a cylindrical surface that is simply in contact with the peripheral surface of the rolling roll 27, or may be provided with a tooth profile that meshes with the rack tooth profile of the peripheral surface of the rolling roll 27.

In the rack shaft manufacturing apparatus 20, as shown in FIG. 8, the mandrel 26 has a cross-sectional shape which is separated from the rack tooth formation planned portion of the rack shaft blank 11 via a gap. The machining support surface 90 is provided and the machining support surface 90 has a middle height. At this time, it is preferable that the processing support surface 90 has a middle-height shape by the central flat surface 91 and the tapered surfaces 92, 92 on both sides. The (A) diagram is in the middle of machining, and the (B) diagram is when the machining is completed.

The procedure for manufacturing the rack shaft 10 by the rack shaft manufacturing apparatus 20 will be described below. (1) The mandrel setting device 23 sets the mandrel 26 at the material insertion position between the left and right clamp members 44 and 45.

(2) The rack shaft blank 11 is positioned at the blank insertion position between the left and right clamp members 44, 45, and the mandrel 26 of (1) above is inserted into the rack shaft blank 11. At this time, the end surface of the rack shaft material 11 is abutted against the material stopper 50 provided in the clamp holder 42 to position the holding position of the rack shaft material 11 in the longitudinal direction.

(3) With the material clamp device 22,
The rack shaft material 11 of (2) is attached to the left and right clamp members 44, 4
Hold by 5.

(4) The rolling depth adjusting device 25 sets the clamp holder 42 to an appropriate upward movement position, and then the rolling roll moving device 24 causes the rolling roll 27 to reciprocate. As a result, the rack tooth profile of the rolling roll 27 bites into and slides on the outer peripheral portion of the rack shaft material 11 back-supported by the working support surface 90 of the mandrel 26, and the shallow rack tooth 12
Is rolled by cold working.

(5) After that, every time the rolling roll 27 slides with respect to the rack shaft material 11 in the above (4) sliding stroke, the rolling depth adjusting device 25 moves the clamp holder 42 upward to move it to the rack shaft material 11. The axial distance from the rolling roll 27 is narrowed, the depth of the rack teeth 12 is gradually increased, and finally the rack teeth 12 having a predetermined depth are formed.

(6) After completion of the rolling in (5) above, the mandrel 26 is removed by the mandrel setting device 23, and the holding of the rack shaft material 11 by the left and right clamp members 44, 45 is released by the material clamping device 22. To do.

The operation of this embodiment will be described below. The rack teeth 12 can be rolled on the rack shaft material 11 by relatively sliding the rack shaft material 11 and the rolling roll 27 in the tangential direction of the rolling roll 27 by the rolling roll moving device 24. At this time, the rolling roll 27 is pressed against the rack shaft material 11, but since the rack shaft material 11 slides in the tangential direction relative to the rolling roll 27, the rolling roll 27 bites into the rack shaft material 11. While rotating by the tangential force, the rack teeth 12 are rolled on the rack shaft material 11.

When the rolling pressure acts to bend the roll shaft of the rolling roll 27, the backup support device 110 can prevent the bending deformation of the roll shaft of the rolling roll 27. Therefore, it is not necessary to increase the diameter of the rolling roll in order to secure the bending rigidity of the roll shaft of the rolling roll 27, and the device can be downsized.

As described above, even if the diameter of the rolling roll is reduced, the roll shaft of the rolling roll 27 does not easily bend, and as a result, the rolling rack teeth 12 can be machined with high precision and the rolling pressure can be increased.

As described above, since the diameter of the rolling roll can be reduced, the contact area between the rolling roll 27 and the surface to be processed is reduced, and the pressure contact force per unit area is increased,
As a result, the swelling of the processed portion per one sliding stroke of the rolling roll 27 can be increased and the processing time can be shortened.

In the above, the rolling roll 27 is moved between the rack shaft material 11 and the rack shaft material 11 by the rolling depth adjusting device 25 at every predetermined stroke (for example, every stroke) of the relative sliding with respect to the rack shaft material 11. The distance can be reduced. As a result, the rolling roll 27 bites into the material little by little at each predetermined stroke of the relative sliding, so that the rack teeth 12 can be formed with a relatively small force without requiring a large force at one time. it can. Further, it is possible to form the rack tooth 12 which has less burrs on the formed rack tooth 12 and which is excellent in strength by rolling.

(Second Embodiment) (FIGS. 5 to 7) The second embodiment differs from the first embodiment in that the backup support device 110 is replaced by a backup support as shown in FIG. 7 (C). The device 120 is used.

The backup supporting device 120 is constructed by fixing and supporting the backup bar 121 to the cylinder bracket 71 which is suspended and fixed to the top plate 32 of the pedestal 21 as described above. Backup bar 121
Are arranged so as to pass through the notch holes on both sides of the slide bracket 74. The backup bar 121 is located on the opposite side of the roll shaft center of the rolling roll 27 from the side where the rack shaft material 11 is located, and is located at the center of the body length of the rolling roll 27 (may extend over the entire body length). The rolling roll 27 is backed up and supported in contact with the surface thereof.

The backup support device 120 may be a flat surface that simply contacts the peripheral surface of the rolling roll 27.
Alternatively, the rolling roll 27 may have a tooth profile that meshes with the rack tooth profile on the peripheral surface.

The embodiment of the present invention has been described in detail above with reference to the drawings. However, the specific configuration of the present invention is not limited to this embodiment, and changes in design within the scope not departing from the gist of the present invention can be made. Even if it exists, it is included in the present invention. For example, the rolling depth adjusting device narrows the axial distance between the rolling roll and the rack shaft material for each half stroke of the reciprocating movement of the rack shaft material or for each multiple stroke (every predetermined sliding stroke). May be.

In the present invention, the rack shaft material and the rolling roll may be moved relative to each other. Therefore,
Although the rolling roll moving device 24 is used to reciprocate on the side of the rolling roll in the above embodiment, the rack shaft blank may be reciprocated on the contrary.

[0056]

As described above, according to the present invention, in the rack shaft manufacturing method, the apparatus can be downsized, the processing efficiency can be increased, and the shape accuracy of the rolled rack teeth can be improved.

[Brief description of drawings]

FIG. 1 is a front view showing a first embodiment of the present invention.

FIG. 2 is a side view of FIG.

3 is an enlarged view of a main part of FIG.

FIG. 4 is a cross-sectional view showing a state in which a mandrel is inserted into a rack shaft material.

FIG. 5 is a front view showing a second embodiment of the present invention.

FIG. 6 is a side view of FIG.

FIG. 7 is a schematic view showing a backup support means.

FIG. 8 is a schematic view showing a mandrel.

FIG. 9 is a perspective view showing a rack shaft.

[Explanation of symbols]

10 Rack Shaft 11 Rack Shaft Material 12 Rack Tooth 20 Rack Shaft Manufacturing Device 21 Frame 22 Material Clamping Device (Material Holding Means) 23 Mandrel Setting Device 24 Rolling Roll Moving Device (Sliding Means) 25 Rolling Depth Adjusting Device ( Feeding means) 26 mandrel 27 rolling rolls 110, 120 backup supporting device (backup supporting means)

Claims (2)

[Claims] 1. A rack shaft manufacturing apparatus for manufacturing a rack shaft having rack teeth on its side surface, a material holding means for holding a hollow pipe-shaped rack shaft material with a cored bar inserted in the hollow portion, and a peripheral surface. A rolling roll having a rack tooth profile formed therein and rotatably supported along the rack shaft material, and the material holding means and the rolling roll are slid relative to each other in the tangential direction of the rolling roll. It is characterized by comprising a sliding means and a backup supporting means which is on the opposite side of the roll shaft center of the rolling roll from the side where the rack shaft material is located and which backs up and supports the rolling roll. Rack axis manufacturing equipment. 2. The rack shaft manufacturing apparatus according to claim 1, further comprising a rack shaft material held by the material holding means, and a feeding means for adjusting an axial distance between the rolling rolls.