JP2001105067A - Rack bar, and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and efficiently manufacture a rack bar with a simple constitution, to increase the degree of freedom of the design at a low cost, and to reduce the manufacturing cost. SOLUTION: The manufacturing method of a rack bar includes a thickness difference forming process in which the thickness t1 of a part P1 having a tooth profile of a plate work W is relatively larger than the thickness t2 of a part P2 having no tooth profile, a trimming process in which a side edge WS of the plate work W is trimmed to a predetermined shape so that end faces Wa of side edges facing each other in the longitudinal direction of the work W are butted against and welded to each other in a succeeding bending process, a bending process in which the plate work W is formed in a bar by bending it in a rolling manner in the direction substantially orthogonal to the longitudinal direction thereof, and a tooth profile forming process to form a tooth profile L in the work W.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rack bar and a method for manufacturing the same, and more particularly, to a rack bar having a bar-shaped body and a method for manufacturing the rack bar.

[0002]

2. Description of the Related Art As a conventional technique for manufacturing a rack bar used for a steering bar of an automobile, for example, as disclosed in Japanese Patent Application Laid-Open No. 5-169181, a pipe material is pressed. After forming a flat portion in the longitudinal direction and forming a plurality of teeth in a direction orthogonal to the axial direction of the pipe material, a rack mold is positioned on the outer surface of the flat portion, and then the pipe is placed inside the pipe material. Pressing a punch having an outer diameter smaller than the inner diameter of the material and forming a flat portion corresponding to the flat portion, and moving the punch in the axial direction of the pipe material to convert the flat portion of the pipe material into a rack shape. In a method of manufacturing a rack bar in which a rack tooth profile is formed by making a bite, a pressurized oil is injected into the pipe material from a direction facing the punch press-in side of the pipe material or from the punch press-in side. Supplied, the rack bar manufacturing method which is characterized in that to reduce the frictional resistance between the pipe material and the punch to form the rack teeth type flat portion of the pipe material are known.

Another conventional technique is disclosed in Japanese Unexamined Patent Publication No.
As disclosed in JP-A-246379, a step of applying a pressure from the outer periphery to a part of a relatively thick metal tube to produce a rack forming portion having a semicircular cross section (first molding step). Attached to the mold splitting mold having a concave and convex shape forming a complementary shape with the rack to obtain the processed tube inside,
A step of forming a rack by press-fitting a mandrel having a semicircular cross section from the hole of the metal tube (secondary molding step), and a step of inserting a metal core into the end of the metal tube after the step, and Mounting on a high-pressure lubricating extrusion device having a die for rolling around the periphery, stretching the meat of the metal tube at the end, and thinning the end of the metal tube. It has been known.

[0004] As described above, in the above-mentioned conventional techniques, in any case, a tooth shape is formed on an existing tube or pipe material (hereinafter, collectively referred to as a pipe) formed in advance into a hollow cylindrical shape. Was.

[0005]

However, as described above, in any of the prior arts, since a tooth profile is formed in an existing pipe, the degree of freedom in designing a rack bar is limited. There was a problem. Existing pipes for forming these tooth profiles are generally formed with a uniform thickness and / or a predetermined diameter, and in order to provide a necessary strength, the strength can be secured as a whole. Therefore, there is a problem that a pipe having a wall thickness and / or a diameter of the pipe must be used, and the cost of the pipe is increased. It is also conceivable to increase the thickness of the existing pipes only to form the tooth profile, but it is difficult to partially increase the thickness of such pipes. There was a problem that can not be. Further, when seamless pipes are used seamlessly in these manufacturing methods, the seamless pipes are generally expensive, so that there is a problem that the manufacturing cost is high. On the other hand, when a relatively inexpensive ERW tube is used, a rack is formed at the seam-welded portion.
There is a problem that a defective product is generated and the production yield of the rack bar is reduced, for example, the seam welded portion is broken or a rack cannot be formed accurately. Then, it is very difficult to form a rack in a portion where seam welding is not performed, and there are problems such as an increase in the number of steps for the rack.

The present invention has been made in view of the above problems, and can be easily manufactured with a simple configuration, and can be manufactured at a low cost and under a design of a free size. To provide a rack bar. Another object of the present invention is to provide a hollow cylindrical rack bar that can be easily formed.

Further, the present invention has been made in view of the above-mentioned problems, and it is possible to easily and efficiently manufacture a rack bar with a simple configuration, thereby increasing the design freedom at low cost. It is an object of the present invention to provide a method of manufacturing a rack bar that can reduce the manufacturing cost. Another object of the present invention is to provide a method of manufacturing a rack bar that can reliably form a tooth profile having sufficient strength with a small number of steps. further,
An object of the present invention is to provide a method of manufacturing a rack bar that can form a rack accurately and reliably.
Still another object of the present invention is to provide a method of manufacturing a rack bar that can more easily manufacture a rack bar and reduce the manufacturing cost.

According to the first aspect of the present invention, in order to achieve the above object, a plate-like work is formed in a rod-like shape by bending a plate-like work in a direction substantially perpendicular to its longitudinal direction so as to avoid a side edge in the longitudinal direction. The tooth profile is formed in the position where it fell.

According to a second aspect of the present invention, there is provided a rack bar according to the first aspect, wherein the end faces of the side edges in the longitudinal direction are butted and joined to each other.

According to a third aspect of the present invention, there is provided a rack bar manufacturing method, comprising: a bending step of bending a plate-like work into a rod-like body by bending the plate-like work in a direction substantially perpendicular to a longitudinal direction thereof. Forming a tooth profile on the work.

According to a fourth aspect of the present invention, there is provided a rack bar manufacturing method according to the third aspect, wherein the thickness of a portion forming the tooth profile of the plate-like workpiece is reduced by adjusting the tooth profile. The method may further include a thickness difference forming step of forming a part to be relatively thicker than a part not formed.

According to a fifth aspect of the present invention, there is provided a rack bar manufacturing method according to the third or fourth aspect of the present invention, wherein the tooth profile forming step forms a rough tooth profile on a plate-like workpiece in advance. And a finish molding step of forming a desired final shape of the tooth shape on the workpiece formed in the rod-shaped body.

According to a sixth aspect of the present invention, there is provided a method of manufacturing a rack bar according to any one of the third to fifth aspects, wherein the plate-like workpiece is moved relative to the longitudinal direction in the bending step. The method further includes a trimming step of trimming the side edge of the plate-shaped work into a predetermined shape so that the end faces of the side edges facing each other can be butt-joined.

According to the first aspect of the present invention, the plate-like workpiece is formed into a rod shape having a free size by bending the plate-like workpiece in a direction substantially perpendicular to the longitudinal direction thereof, and at a position avoiding the side edges in the longitudinal direction. The rack bar having the tooth profile formed at an arbitrary position with respect to the rack bar is manufactured by forming the tooth profile.

According to a second aspect of the present invention, in the first aspect of the present invention, a hollow cylindrical rack bar is easily manufactured by abutting and joining the end faces of the side edges in the longitudinal direction to each other.

According to the third aspect of the present invention, a plate-like work having an arbitrary size is bent in a direction substantially perpendicular to the longitudinal direction in a bending step to form a rod-like body. , A rack bar of any size is manufactured.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the thickness of the portion of the plate-shaped workpiece in which the tooth profile is formed in the thickness difference forming step is larger than the thickness of the portion where the tooth profile is not formed. After forming to be relatively thick, a bending step and a tooth profile forming step are performed. Since the portion forming the tooth profile is formed so as to have a large plate thickness, it has sufficient strength even after the tooth profile is formed in the tooth profile forming step.

According to a fifth aspect of the present invention, in the third or fourth aspect of the present invention, a rough tooth profile is previously formed on a plate-like work in a preforming step, and a sheet thickness difference forming step is performed as necessary. After performing the bending process, a finish molding process for forming a tooth profile having a desired final shape is performed. In order to form a desired final shape of a tooth on a workpiece having a rough tooth formed in advance, the tooth is easily and accurately formed.

According to a sixth aspect of the present invention, in the invention according to any one of the third to fifth aspects, the side edge of the plate-shaped work is trimmed into a predetermined shape in the trimming step, so that the plate-shaped work is bent in the bending step. The end faces of the opposing side edges in the longitudinal direction are butt-joined to each other to easily produce a rack bar such as a hollow cylinder, and the joint portion is formed with a tooth profile, which may cause a defect such as a crack. Is prevented.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method of manufacturing a rack bar according to the present invention will be described in detail with reference to the drawings. 1 to 7
8 is a plan view or a vertical sectional front view of a first embodiment of a method of manufacturing a rack bar according to the present invention, which is shown in parallel with a sectional view taken along each arrow, and FIGS. FIG. 9 is a plan view or a vertical sectional front view of a second embodiment of a method of manufacturing a rack bar according to the present invention, and a cross-sectional view taken along each arrow. FIGS. 15 to 17 are diagrams for forming a rack bar into a hollow pipe shape by butt-joining end surfaces Wa of side edges opposed to each other in the longitudinal direction of a plate-shaped work W as described below. 18 to 20 are perspective views showing different embodiments, respectively, and FIGS. 18 to 20 are perspective views showing an embodiment of a rack bar having a cross section different from that of a hollow cylinder. 7 and 14 show a rack bar of the present invention manufactured by applying the manufacturing method of the present invention. In the drawings, the same reference numerals denote the same or corresponding parts. Note that the rack bar manufactured by the present invention includes a case where the cross-section is formed in a completely hollow cylindrical pipe-like rod having a substantially annular cross-section, and a cross-section substantially U-shaped (FIG. 5). Or see FIG. 12),
A rectangular (FIG. 18) or triangular (FIG. 19), and a section that does not form a tooth shape has a substantially Y-shaped cross section (FIG. 2).
0) etc. are also included.

First, a first embodiment of the method of manufacturing a rack bar according to the present invention will be described. The method of manufacturing a rack bar according to the present invention generally includes a bending step of forming a bar-shaped body by bending a plate-shaped work W so as to be rounded in a direction substantially perpendicular to the longitudinal direction, and forming a tooth shape L on the work W. And a step of forming a tooth profile.

In the first embodiment shown in FIGS. 1 to 7, a portion P of the plate-like workpiece W which forms the tooth shape is further provided.
The thickness difference forming step in which the thickness t1 of the workpiece W is relatively thicker than the thickness t2 of the portion P2 where the tooth shape is not formed, and the opposing side edges in the longitudinal direction of the workpiece W in the bending step. And a trimming step of trimming the side edge WS of the plate-shaped work W into a predetermined shape so that the end faces Wa can be butt-joined.

As shown in FIG. 1, when manufacturing a rack bar, an initial work W is formed in a rectangular plate shape. The plate-shaped work W is formed so as to have a thickness t1 as shown in a sectional view on the right side of FIG. As shown in FIGS. 2 to 4, the plate-shaped work W formed in this manner is located substantially at the center in the width direction (vertical direction in the drawing) and extends along the longitudinal direction. To form a tooth profile (the tooth profile forming portion P
1) is set.

As shown in FIG. 2, in the plate-shaped work having the thickness t1, the portion where the tooth profile is not formed (the non-tooth profile forming portion P2) is larger than the thickness t1 except for the tooth profile forming portion P1. It is crushed to a thin thickness t2. That is, a sheet thickness difference forming step of forming the sheet thickness t1 of the tooth shape forming portion P1 so as to protrude and become thicker than the sheet thickness t2 of the non-tooth shape forming portion P2 is performed. In this plate thickness difference forming step, for example, although not shown, the non-tooth profile forming portion P2 is entirely formed by a press die or the like provided with a concave portion or the like according to the position and size of the tooth profile forming portion P1. Can be crushed by press working so as to have a thickness t2 at one time, and a roller provided so as not to roll the tooth-forming portion P1 is pressed against the non-tooth-forming portion P2 while pressing the roller. By rolling in the longitudinal direction, the side edges along the tooth profile forming portion P1 are successively set to the thickness t2.
It can also be rolled by roll processing so that When this roll processing is performed, even in the non-tooth-shaped portion P2, the portion adjacent to the tooth-shaped portion P1 in the longitudinal direction of the work W is not rolled and has the same thickness as the tooth-shaped portion P1. t1 is maintained (see the shape shown by the two-dot chain line in FIG. 2).

By rolling the non-tooth-shaped portion P2, the rectangular work W is deformed as shown in FIG. Therefore, as shown in FIG. 3, before being formed into a rod-shaped body in a later bending step, the deformed plate-shaped work W
A trimming step of trimming the side edge WS to a predetermined shape is performed. In the trimming, the width of the work W (the length in the vertical direction in the plan view shown on the left side of FIG. 3) is equal to the circumference of the rack bar to be manufactured, and the length of the work W in the longitudinal direction (FIG. 3 (the length in the left-right direction in the plan view shown to the left of FIG. 3) is equal to the length of the rack bar to be manufactured. Although FIG. 3 shows a case where the longitudinal side edges of the work W positioned vertically opposite to each other are formed linearly, as will be described later in detail with reference to FIG. When the end faces Wa of the side edges in the longitudinal direction of W are butted and joined together, the side edges may be formed in a symmetrical shape so as to be combined with each other.

Thereafter, the side edges in the longitudinal direction of the trimmed workpiece W are bent slightly inward in the same direction as the direction in which the tooth-forming portion P1 projects from the non-tooth-forming portion P2, as shown in FIG. Is done. Next, as shown in a sectional view to the right of FIG. 5, the workpiece W is bent in a direction substantially perpendicular to the longitudinal direction to form a U-shape in order to form the workpiece W into a hollow cylindrical rod-shaped body. As shown in the cross-sectional view to the right, the bending process is performed so that the cross-sectional outer shape becomes a substantially circular pipe shape, and the workpiece W is formed as shown in FIGS.
The end faces Wa of the side edges in the longitudinal direction are abutted to each other and joined and fixed by continuous welding (FIG. 15), spot welding (FIG. 16), or caulking (FIG. 17). Here, the tooth-shaped forming portion P1 formed relatively thicker than the non-tooth-shaped forming portion P2 in the above-described plate thickness difference forming step is set substantially at the center of the plate-shaped work W in the width direction. By being arranged, the end surfaces Wa of the side edges in the longitudinal direction of the workpiece W formed in the shape of a hollow pipe are located on the opposite side to the butt-joined portion. When the manufactured rack bar is formed in a rod-like body having a substantially U-shaped cross section, the step of slightly bending the longitudinal side edge of the workpiece W shown in FIG. 4 and the step shown in FIG. It is not necessary to perform a step of abutting and joining the end surfaces Wa of the side edges in the longitudinal direction of the work W.

Subsequently, as shown in FIG. 7, the tooth profile forming portion P1 is formed by a cutting tool such as a rack cutter or the like, so that the tooth profile forming portion P1 is formed in a direction substantially perpendicular to the longitudinal axis of the rack bar or in a direction perpendicular thereto. A plurality of tooth profiles L are formed in a direction inclined at a predetermined angle with respect to the direction.

The rack bar manufactured according to the above-described method is formed into a rod shape by bending a plate-like work W in a direction substantially perpendicular to the longitudinal direction, and avoids the side edges in the longitudinal direction. A tooth profile L is formed at the position,
The end faces Wa of the side edges in the longitudinal direction are butted and joined to each other. Then, in this embodiment, the tooth profile forming portion P
1 is formed thick, and is located on the opposite side of the butt joint portion of the end face Wa,
A tooth profile L having sufficient strength can be easily and reliably formed. In addition, unlike the case of manufacturing from a conventional pipe-shaped work, a plate-shaped work W is formed by bending a plate-shaped work W. Therefore, by changing the length of the work W in the width direction, It is possible to easily and inexpensively manufacture a rack bar having a desired size such as a diameter and a height width in a cross section.

Next, a second embodiment of the method of manufacturing a rack bar according to the present invention will be described with reference to FIGS. In the description of this embodiment, the first
Only the parts different from the first embodiment will be described, and the same or equivalent contents as those of the first embodiment will be described.
The same reference numerals are given and the description is omitted.

In the method of manufacturing a rack bar according to the present embodiment, a tooth profile forming step of forming a tooth profile L on a workpiece W is roughly a preforming step of forming a rough tooth profile L1 on a plate-shaped workpiece W in advance, and a rod-shaped body. And a finish molding step of forming a tooth profile L2 having a desired final shape on the workpiece W formed in the step (a).

As shown in FIG. 8, the initial work W for manufacturing the rack bar is the first embodiment (FIG. 1).
Similarly, is formed in a rectangular plate shape having a thickness t1. In addition, the tooth profile forming portion P1 is set at a position substantially at the center in the width direction of the work W and extends along the longitudinal direction thereof.

Then, for example, although not shown, the tooth shape forming portion P1 of the plate-like work W is pressed by a press die provided with a rack die for forming the coarse tooth shape L1, and a preforming step is performed. I do. As a result, as shown in FIG. 9, a rough tooth shape L1 is formed on the tooth shape forming portion P1 of the work W which is initially plate-shaped so as to protrude from the non-tooth shape forming portion P2. Since the work W which has been rectangular is deformed as shown in FIG. 9 by forming the rough tooth shape L1, as shown in FIG. In the same manner as in the first embodiment, a trimming step of cutting off the side edge WS of the deformed plate-shaped work W and trimming it into a predetermined shape is performed.

Thereafter, as in the first embodiment, FIG.
As shown in FIG. 1, the tooth-forming portion P1 is
It is bent slightly inward in the same direction as the direction projecting from 2. Next, as shown in a cross-sectional view to the right of FIG. 12, the workpiece W is bent in a direction substantially perpendicular to the longitudinal direction to form a U-shape so as to form a rod-shaped body. As shown in the drawings, a bending process is performed so that the cross-sectional outer shape becomes substantially circular, and as shown in FIGS. 15 to 17, the end faces Wa of the side edges in the longitudinal direction of the work W are abutted and joined and fixed. , Formed into a hollow pipe shape. The tooth profile forming portion P1 where the rough tooth profile L1 is formed in the preforming step is:
Since the plate-shaped work W is set and arranged substantially at the center in the width direction, the work W in the shape of a hollow pipe is located on the side opposite to the part where the end faces Wa of the side edges in the longitudinal direction are butt-joined. Will be done.

Subsequently, for example, though not shown, the core W (mandrel) is moved in the axial direction with respect to the work W formed in a hollow pipe shape, so that the work W is pressed into a rack shape. As shown in FIG. 14, a finish molding step of finally forming a necessary tooth shape L2 on the tooth forming portion P1 of the workpiece W on which the rough tooth shape L1 has been formed is performed.

It should be noted that the present invention is not limited to the above-described embodiment, and the non-tooth-shaped portion P2 may be crushed to reduce the thickness t of the tooth-shaped portion P1 as shown in the first embodiment.
1 is formed so as to protrude and become thicker than the plate thickness t2 of the non-tooth-shaped portion P2, and press-work the tooth-shaped portion P1 to form a rough tooth L1. Steps can also be performed.

The rack bar manufactured according to the present invention is not limited to a complete hollow cylindrical shape having a substantially annular cross section or a substantially U-shaped shape as described above. For example, as shown in FIG. The cross section can be formed in a substantially rectangular shape as shown in FIG. 19, or the cross section can be formed in a hollow angle shape having a substantially triangular shape as shown in FIG. 19, and further, as shown in FIG. If necessary, a rack bar having a free cross-sectional shape can be manufactured, for example, a cross-section of a side edge that does not form the tooth shape L because the adjacent inner side surfaces are joined and fixed so as to be in contact with each other. And, in particular,
As shown in FIG. 20, when the inner surfaces near the end surfaces Wa of both side edges in the longitudinal direction of the work W are brought into contact with each other, they can be joined and fixed by spot welding or the like.

The rack bar manufactured according to the method of the second embodiment as described above has the same structure as that of the first embodiment, and the tooth profile forming portion P1 has the rough tooth profile L1 previously formed. In addition, similarly to the first embodiment, since the end face Wa is located on the side opposite to the butt joint portion, the tooth profile L having sufficient strength can be easily and reliably formed. . In addition, unlike the case of manufacturing from a conventional pipe-shaped work, a plate-shaped work W is formed by bending a plate-shaped work W. Therefore, by changing the length of the work W in the width direction, A rack bar having a desired diameter can be easily and inexpensively manufactured.

[0038]

According to the first aspect of the present invention, the plate-like work is formed into a rod shape by bending the plate-like work in a direction substantially perpendicular to the longitudinal direction, and the tooth shape is formed at a position avoiding the side edges in the longitudinal direction. Accordingly, it is possible to provide a rack bar that can be easily manufactured with a simple configuration and that can be manufactured at a low cost with a design of a free size.

According to the second aspect of the present invention, there is provided the hollow cylindrical rack bar according to the first aspect of the present invention, which can be easily formed by butt-joining the end faces of the longitudinal side edges to each other. Can be provided.

According to the third aspect of the present invention, the bending step of forming the rod-shaped body by bending the plate-shaped work in a direction substantially orthogonal to the longitudinal direction thereof, and the step of forming the tooth shape in the work are performed. A rack bar manufacturing method capable of easily and efficiently manufacturing a rack bar with a simple configuration including the above structure, thereby increasing the freedom of design at low cost and reducing the manufacturing cost. Can be provided.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the thickness of the portion of the plate-shaped workpiece that forms the tooth profile is relatively larger than the thickness of the portion that does not form the tooth profile. By further including a thickness difference forming step of forming a rack bar, a method of manufacturing a rack bar capable of reliably forming a tooth profile having sufficient strength with a small number of steps can be provided.

According to a fifth aspect of the present invention, in the third or fourth aspect of the invention, the tooth profile forming step includes a preforming step of previously forming a coarse tooth profile on a plate-shaped work, and a tooth shape forming step. And a finish molding step of forming a tooth profile having a desired final shape on the work, thereby providing a method of manufacturing a rack bar capable of accurately and reliably forming a rack.

According to a sixth aspect of the present invention, in the invention according to any one of the third to fifth aspects, in the bending step, the end faces of the longitudinally opposed side edges of the plate-shaped work are butt-joined. By further including a trimming step of trimming a side edge of a plate-shaped work into a predetermined shape so that a rack bar having a hollow pipe shape or the like can be manufactured more easily and a manufacturing cost can be reduced. And a method for manufacturing a rack bar having a hollow pipe shape or the like.

[Brief description of the drawings]

1A and 1B are an initial plan view (left side) and a cross-sectional view (right side) of a work, for explaining a first embodiment of a method of manufacturing a rack bar according to the present invention.

FIG. 2 is a plan view (left side) and a cross-sectional view (right side) of a work, showing a state in which a thickness difference forming step has been performed from the state of FIG.

3A and 3B are a plan view (left side) and a cross-sectional view (right side) of a work, showing a state in which a trimming process has been performed from the state of FIG. 2;

FIG. 4 is a plan view (left side) and a cross-sectional view (right side) of the work, showing a state in which a side edge in the longitudinal direction of the work is slightly bent from the state of FIG. 3;

5 is a vertical front view (left side) of the work and a side view of the work, showing a state in which the work is bent in a direction substantially perpendicular to the longitudinal direction from the state of FIG. It is a figure (right side).

6 is a longitudinal front view (left side) of the work and a longitudinal side view thereof, showing a state in which the work is further bent from the state of FIG. (Right).

7 is a vertical front view (left side) and a vertical side view (right side) of a rack bar of the present invention manufactured by forming a tooth profile on the tooth profile forming portion of the work from the state of FIG.

8A and 8B are an initial plan view (left side) and a cross-sectional view (right side) of a work, for explaining a rack bar manufacturing method according to a second embodiment of the present invention.

FIG. 9 is a plan view (left side) and a cross-sectional view (right side) of a work, showing a state where a preforming step has been performed from the state of FIG. 8;

10 is a plan view (left side) and a cross-sectional view (right side) of the workpiece, showing a state where a trimming process has been performed from the state of FIG. 9;
It is.

11 is a plan view (left side) of the work, showing a state in which a side edge in the longitudinal direction of the work is slightly bent from the state of FIG. 10;
And its sectional view (right side).

12 is a vertical front view (left side) of the work, showing a state in which the work is bent in a direction substantially perpendicular to the longitudinal direction from the state of FIG. It is a figure (right side).

13 is a longitudinal front view (left side) of the work and a longitudinal side view thereof, showing a state in which the work is further bent from the state of FIG. 12 and the end faces of the side edges in the longitudinal direction are joined to each other to form a hollow pipe shape. (Right).

14 is a vertical front view (left side) and a vertical side view (right side) of a rack bar of the present invention manufactured by forming a tooth profile on the tooth profile forming portion of the work from the state of FIG.

FIG. 15 is a perspective view showing a state where the side edges in the longitudinal direction of the work are joined and fixed by abutting and mutually welding end faces of the side edges in the longitudinal direction.

FIG. 16 is a perspective view showing a state in which the side edges in the longitudinal direction of the work are joined and fixed by spot welding with the end faces abutting each other.

FIG. 17 is a perspective view showing a state in which the end faces of the side edges in the longitudinal direction of the work are formed in a symmetrical shape that can be combined, and are combined and caulked.

FIG. 18 is a partial perspective view of a rack bar showing an embodiment when the cross section is formed to be substantially rectangular.

FIG. 19 is a partial perspective view of a rack bar showing an embodiment in which the cross section is formed to be substantially triangular.

FIG. 20 is a partial perspective view of a rack bar showing an embodiment in a case where a section where a tooth profile is not formed is formed to be substantially Y-shaped.

[Explanation of symbols]

 W Work Wa End face of side edge of work WS Side edge of work to be trimmed L Tooth L1 Coarse L2 Desired final shape P1 Tooth forming part P2 Non-tooth forming part t1 Thickness of tooth forming part t2 Non-tooth Forming part thickness

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hiroshi Ishikawa 1-Toyota-cho, Toyota-shi, Aichi F-term in Toyota Motor Corporation (Reference) 4E087 AA10 BA19 CA17 CA27 CA31 CA51 DA04 DB01 DB02 DB07 EC15 EC38 HA06 HA38 HA82

Claims (6)

[Claims] 1. A rack bar, wherein a plate-shaped workpiece is bent in a direction substantially perpendicular to its longitudinal direction to be formed in a rod shape, and a tooth profile is formed at a position avoiding a side edge in the longitudinal direction. 2. The rack bar according to claim 1, wherein the end faces of the side edges in the longitudinal direction are butted and joined to each other. 3. A rack comprising: a bending step of bending a plate-like work into a rod-like body by bending the work in a direction substantially perpendicular to a longitudinal direction thereof; and a tooth-forming step of forming a tooth shape on the work. Bar manufacturing method. 4. The method according to claim 1, further comprising a thickness difference forming step of forming a portion of the plate-shaped workpiece in which a tooth profile is formed to be relatively thicker than a portion of the plate-shaped workpiece in which the tooth profile is not formed. The method for manufacturing a rack bar according to claim 3, wherein 5. The tooth profile forming step includes: a preforming step of forming a rough tooth profile on a plate-shaped workpiece in advance; and a finish molding step of forming a desired final tooth profile on a bar-shaped workpiece. The method for manufacturing a rack bar according to claim 3, wherein the method includes: 6. A trimming step of trimming a side edge of a plate-shaped work into a predetermined shape so that end faces of opposed side edges in a longitudinal direction of the plate-shaped work can be butt-joined in a bending step. The method for manufacturing a rack bar according to any one of claims 3 to 5, further comprising: