JP3685710B2 - Rack bar and its manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rack bar used in an automobile steering apparatus and a method for manufacturing the same.
[0002]
[Prior art]
As an automobile steering device, a pinion provided on a handle shaft is engaged with an uneven tooth portion of a rack bar provided on the vehicle body side so as to be movable in the left-right axis direction, and the handle is rotated to pass through the uneven tooth portion. 2. Description of the Related Art A rack and pinion type steering device configured to move a rack bar in a left-right direction to steer a wheel is known.
[0003]
The rack bar of this steering device has been manufactured to have a hollow structure as the weight of the vehicle body is reduced, and the forging process is repeated a plurality of times to form an uneven tooth portion near the tip of the outer surface of the pipe body. Have been made.
[0004]
[Problems to be solved by the invention]
However, in the production of this hollow rack bar, it is necessary to repeat the forging process 7 to 8 times or more in order to form a tooth having a large height, which may damage the mold of the forging device and cause damage. In addition, the teeth in the process of molding were damaged, and the production was accompanied by great labor and difficulty. In addition, since the upper limit height of teeth that can be formed is determined by the thickness of the pipe body, there is a problem that it is difficult to manufacture rack bars having different product specifications. In addition, there has been a problem that a rack bar with overall warpage (bending) is produced by repeating the forging process 7 to 8 times.
[0005]
Accordingly, the present invention provides a high-accuracy rack bar that is light and free of warping and solves the above-described problems, and provides a method that can manufacture the rack bar at a low cost with a small number of manufacturing steps. The purpose is to do.
[0006]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, a rack bar according to the present invention has a cross-section C having a strip-shaped rack plate having an uneven tooth portion on the outer surface and an opening formed by being cut out in the longitudinal direction near the tip. comprising a pipe in which the rack plate Ru are bonded to close the opening of the uneven teeth includes a shaped portion as an external exposed shape, and the rack plate, a pair of long sides facing each other, the A curved side portion having an edge formed with an engagement concave portion / engagement convex portion having a substantially S-shaped cross section toward the opposite side to the uneven tooth portion is formed in a protruding shape, and the pipe body The C-shaped part is provided with an engagement convex part / engagement concave part that can be engaged with the engagement concave part / engagement convex part of the rack plate on each of the pair of cut-out edges .
[0007]
Also, the manufacturing method of the rack bar according to the present invention includes a pair of concave and convex teeth in the longitudinal direction on one surface of the strip material, and a pair of engagement recesses and engagement projections having substantially S-shaped cross sections at the edges. A protruding bent side portion is plastically processed to form a rack plate, and the pipe body is notched in the longitudinal direction to form a cross-sectional C-shaped portion , and a pair of notched edges of the C-shaped portion The engaging recesses / engagement recesses engageable with the engagement recesses / engagement projections are plastically processed to form the engagement recesses / engagement projections of the bent side portions of the rack plate. The engagement projections and the engagement recesses of the cut-out edge of the pipe body are brought into an engaged state and are pressed and joined.
[0008]
In addition, the concave and convex tooth portions are plastically processed in the longitudinal direction on one surface of the band plate material, and the rack portions are formed by plastic processing of the protrusions along the long side portions on both sides , and near the tip of the outer surface of the pipe body , A concave portion having a rectangular shape with a front end opening in the longitudinal direction and a flat bottom surface and a pair of raised portions disposed in the longitudinal direction on the outer portion of the concave portion are plastically processed, and the concave and convex tooth portions are exposed as described above. The rack plate is placed in the concave portion of the pipe body, and the pair of raised portions are caulked to the rack plate side to press the protrusions, thereby fixing the rack plate to the pipe body .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments.
[0010]
FIG. 1 shows a reference example of a rack bar according to the present invention. This rack bar is connected to a solid rack bar 1 having an uneven tooth portion 2 on the outer surface and a base end 1a of the rack bar 1. And a pipe body 3.
[0011]
An example of the manufacturing method of the rack bar will be described. First, the rack bar body 1 is formed by plastic working the concave and convex tooth portions 2 in the axial direction on the outer surface of the solid bar material by warm forging. In this forging process, a small-diameter portion 5 having an outer diameter substantially equal to the inner diameter of the pipe body 3 is formed on the base end 1 a side of the rack bar 1, and a large-diameter bulge is formed at the base end of the small-diameter portion 5. A protruding portion 6 is formed. In this forging process, even a tooth 4 having a large height H can be formed in about two steps. After the rack bar 1 is formed, a burr trimming step is performed.
[0012]
On the other hand, as shown in FIG. 2, in the pipe body 3, the diameter of the tip hole portion 7 is expanded by plastic working to such an extent that the bulging portion 6 of the base end 1 a of the rack bar 1 can be inserted in advance. Thereafter, the base end 1a of the rack rod body 1 is inserted into the tip hole portion 7 of the pipe body 3, and the diameter of the distal end 3a of the pipe body 3 is reduced by plastic working (squeezing processing), whereby the base of the rack rod body 1 is obtained. The end 1a and the tip 3a of the pipe body 3 are connected. Specifically, for example, the pipe body 3 and the rack bar 1 are passed through the die 8 from the base end 3b side of the pipe body 3 and the diameter 3 of the distal end 3a is squeezed (pressed) as shown in FIG. And
[0013]
Thus, by producing the necessary uneven tooth portion 2 independently from the pipe body 3, a rack bar can be manufactured at a low cost with a small number of steps. At this time, in the conventional manufacturing method in which the uneven tooth portion is directly forged and formed on the pipe, the height of the tooth of the uneven tooth portion is greatly limited by the wall thickness of the pipe, and there is a limit to the height of the tooth that can be formed. According to the invention, the height of the teeth 4 and the wall thickness of the pipe body 3 are irrelevant, and even the teeth 4 having a large height H can be easily formed. In addition, the rack bar itself is reduced in weight by the pipe body 3 and has a structure in which the rack bar body 1 and the pipe body 3 are connected (not the plastic processing of teeth directly on the pipe). It is obtained as a straight (with no warping) and with high dimensional accuracy.
[0014]
Next, FIG. 3 shows a first embodiment of the rack bar of the present invention. This rack bar has a strip-shaped rack plate 9 having uneven tooth portions 2 on the outer surface and the uneven tooth portions 2 exposed to the outside. And a pipe body 3 joined to the rack plate 9 as a shape.
[0015]
As shown in FIG. 3 and FIG. 4 (a), the rack plate 9 has the concave and convex tooth portion 2 and a pair of opposing long sides (left and right sides in FIG. 4) opposite to the concave and convex tooth portion 2. There are curved side portions 10 and 10 facing (constituting a part of the outer peripheral wall of the pipe body 3), and the edge of the curved side portion 10 has, for example, an engagement concave portion 21a having a substantially S-shaped cross section. And an engaging convex portion 21b. In the present embodiment, the case where the engaging concave portion 21a is disposed outside and the engaging convex portion 21b is disposed inside is illustrated.
[0016]
Further, the pipe body 3 is notched in the longitudinal direction near the tip 3a to form a cross-sectional C-shaped portion 11, and the engagement recess 21a / engagement is formed on the notched end edges 12 and 12 of the C-shaped portion 11. Engaging convex portions 22a and engaging concave portions 22b having shapes that can be engaged with the convex portions 21b are provided.
[0017]
An example of the manufacturing method of this rack bar will be described. As shown in FIGS. 3 and 4 (b), first, in the strip plate material, the concave and convex tooth portions 2 are plastically processed (forged) in the longitudinal direction on one surface thereof. The rack plate 9 is produced by plastic processing the pair of bent side portions 10 and 10 having the engaging concave portion 21a and the engaging convex portion 21b. On the other hand, the pipe body 3 is cut in the longitudinal direction near the tip 3a by cutting / cutting or the like to form a cross-sectional C-shaped part 11, and then the cut-out edges 12 and 12 of the C-shaped part 11 are plastic processed. An engaging convex portion 22a and an engaging concave portion 22b are formed.
[0018]
Thereafter, the rack plate 9 is disposed in the opening 13 of the C-shaped section 11 of the pipe body 3, the edges of the bent side portions 10, 10 of the rack plate 9, and the notched edges 12, 12 of the pipe body 3. Are joined to each other by plastic working. That is, the engagement convex portion 22a and the engagement concave portion 22b of the pipe body 3 are pressed into contact with the engagement concave portion 21a and the engagement convex portion 21b of the rack plate 9 from the outside (crimped) to join the engagement state.
[0019]
Even in this rack bar manufacturing method, by producing the concave and convex tooth portion 2 independently from the pipe body 3, the rack bar can be manufactured with a small number of steps and at a low cost, and the thickness of the pipe is increased by the thickness of the pipe. The teeth 4 having a large height H can be easily obtained. Note that the engagement concave portion 21a / engagement convex portion 21b of the rack plate 9 and the engagement convex portion 22a / engagement concave portion 22b of the pipe body 3 may have opposite shapes in which the inner and outer positions are interchanged.
[0020]
Next, FIG. 5 shows a second embodiment of the present invention. This rack bar has a strip plate rack plate 9 having an uneven tooth portion 2 on the outer surface and a rack plate with the uneven tooth portion 2 exposed to the outside. The pipe body 3 joined to the plate 9 is provided, and the joining structure of the rack plate 9 and the pipe body 3 is different (from the first embodiment).
[0021]
As shown in FIGS. 5 and 6, the rack plate 9 is projected on both long sides of the plate main body 15 facing each other and on the same surface as the inner surface (on the side opposite to the concavo-convex tooth portion 2). Parts 16 and 16 are provided. The pipe body 3 is provided with a concave portion 17 in the longitudinal direction near the tip 3a.
[0022]
An example of the manufacturing method of this rack bar will be described. First, as shown in FIG. 5 and FIG. 6 (B), first, in the belt plate material, the uneven tooth portion 2 is plastically processed in the longitudinal direction on one surface thereof, and The protrusions 16 and 16 are plastically processed along the pair of long sides to produce the rack plate 9. On the other hand, the pipe body 3 is formed with a recess 17 having a rectangular shape with a distal end opening in the longitudinal direction near the distal end 3a of the outer surface by plastic working. At this time, the bottom surface of the concave portion 17 is formed flat, and a pair of raised portions 18, 18 in the longitudinal direction are formed on the outer portion of the concave portion 17.
[0023]
Thereafter, the rack plate 9 is placed in (inserted into) the concave portion 17 of the pipe body 3 with the concave and convex tooth portions 2 exposed to the outside, and the outer portion of the concave portion 17 is plastically processed to fix the rack plate 9. That is, as shown in FIGS. 6 (b) to 6 (a), the pair of raised portions 18, 18 of the pipe body 3 are caulked to the rack plate 9 side so that the protrusions 16, 16 are pressed against the rack plate. 9 is fixed to the pipe body 3.
[0024]
Next, FIG. 7 and FIG. 8 show other reference examples. This rack bar is obtained by plastically processing the concave and convex tooth portions 2 in the longitudinal direction on one surface of the strip material, and close to the tip 3 a of the outer surface of the pipe body 3. The flat surface portion 19 is plastically processed in the longitudinal direction, and the other surface of the rack plate 9 is welded (for example, beam welding) to the flat surface portion 19 of the pipe body 3.
[0025]
FIG. 9 and FIG. 10 show still another reference example. In this rack bar, the flat surface portion 19 is plastically deformed in the longitudinal direction near the tip 3a of the outer surface of the pipe body 3, and the rack plate 9 is formed. It is manufactured by welding to the flat surface portion 19. That is, a concave portion having a flat bottom surface is formed near the outer end 3a of the outer surface of the pipe body 3, and the rack plate 9 is welded in a state where the rack plate 9 is fitted to the concave portion with almost no gap. In this case, the rack plate 9 is reinforced against a load (displacement) in the longitudinal direction.
[0026]
【The invention's effect】
Since this invention is comprised as mentioned above, there exists an effect described below.
[0027]
(According to claim 1) Since the whole is a hollow structure, the weight can be further reduced, and since the rack plate 9 and the pipe body 3 are connected to each other, the whole is straight (without warping). A rack bar with high dimensional accuracy.
[0028]
(According to claim 2 or 3 ) By producing the rack plate 9 in which the uneven tooth portion 2 is plastically processed separately from the pipe body 3, the rack bar is manufactured with a small number of steps and at a low cost. be able to. At this time, the tooth height is not greatly limited by the wall thickness of the pipe as in the case of forging the uneven tooth portion directly on the pipe (as in the prior art), and the tooth 4 having a large height dimension H is used. Even so, it can be easily molded.
Also, the rack bar can be produced straight without the pipe being warped (bent) by repeating the plastic processing of the teeth directly on the pipe (as in the prior art). In addition, the manufacturing equipment can be simplified and simplified.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional front view showing a reference example .
FIG. 2 is an explanatory diagram of a method for manufacturing a rack bar.
FIG. 3 is a sectional front view showing the first embodiment of the present invention.
FIG. 4 is an explanatory diagram of a method for manufacturing a rack bar.
FIG. 5 is a perspective view showing a main part of a second embodiment of the present invention.
FIG. 6 is an explanatory diagram of a method for manufacturing a rack bar.
FIG. 7 is a cross-sectional front view of an essential part showing another reference example .
FIG. 8 is an explanatory diagram of a method for manufacturing a rack bar.
FIG. 9 is a sectional front view of an essential part showing still another reference example .
FIG. 10 is an explanatory diagram of a method for manufacturing a rack bar.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rack rod 1a Base end 2 Concavity and convexity part 3 Pipe body 3a Tip 7 Tip hole 9 Lap rate
10 curve side
11 Cross section C-shaped part
12 Notched edge
13 openings
16 ridges
17 Recess
18 ridges
19 Flat surface
21 a Engaging recess
21 b Engaging projection
22 a Engaging projection
22 b Engaging recess

Claims (3)

A strip-shaped rack plate 9 having the uneven teeth 2 on an outer surface, exposed outside the uneven teeth 2 provided with a cross-section C-shaped portion 11 having an opening 13 formed cut away in the longitudinal direction at the front end 3a toward the rack plate 9 is provided with a, a pipe 3 that will be joined to close the opening 13 as Jo,
The rack plate 9, the pair of long sides facing, the uneven teeth 2 opposite transverse surface substantially facing the side S-shape engaging recess 21 a · engaging convex portion 21 b is formed an end Folded sides 10 , 10 having edges are formed in a protruding shape,
And the C-shaped portion 11 of the pipe 3, the s husband pair of notches edges 12, 12, the engaging recesses 21 a · engaging convex portion 21 b engageable with the engagement of the rack plate 9 convex portion 22 a · engaging recess 22 b is, the rack and wherein the provided bar. Curved side portions 10 of the pair projecting shape having an engaging recess 21 a · engaging convex portion 21 b of the cross section substantially S-shape edge with plastic working in the longitudinal direction to the uneven teeth 2 on one surface of the strip plate material , 10 are plastically processed to form the rack plate 9, and the pipe body 3 is cut in the longitudinal direction near the tip 3a to form a cross-sectional C-shaped portion 11 and a pair of cut-out ends of the C-shaped portion 11 the edges 12, 12, the engaging recess 21 a · engaging convex portion 21 b can engage the engaging projection 22 a · engaging recess 22 b, and plastic working,
The engagement concave portion 21 a and the engagement convex portion 21 b of the bent side portion 10 of the rack plate 9 are connected to the engagement convex portion 22 a and the engagement concave portion 22 b of the notched end edge 12 of the pipe body 3. The rack bar is manufactured by press-contacting and joining them in an engaged state . On the one surface of the strip material, the concave and convex tooth portions 2 are plastically processed in the longitudinal direction, and the protrusions 16 and 16 are plastic processed along the long side portions on both sides to form the rack plate 9, and the outer surface of the pipe body 3 the tip 3a closer, a recess 17 having a tip opening rectangular and flat bottom in the longitudinal direction, a pair of raised portions 18, 18 disposed longitudinally outward portions of the recess 17, to plastic working, and
The rack plate 9 is placed in the concave portion 17 of the pipe body 3 with the concave-convex tooth portion 2 exposed to the outside, and the pair of raised portions 18 , 18 are caulked to the rack plate 9 side to form the ridge portion 16. , 16 is pressed to fix the rack plate 9 to the pipe body 3 .

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