JP6661867B2 - Rack guide and rack and pinion type steering device provided with the rack guide - Google Patents

Description

  The present invention relates to a technology of a rack guide and a rack and pinion type steering device including the rack guide.

Generally, a rack and pinion type steering device includes a gear case, a pinion pivotally supported by the gear case, a rack bar formed with rack teeth meshing with the pinion, and a slidable rack bar within the gear case. And a coil spring that urges the rack guide to press the rack guide against the rack bar.
The rack guide has conventionally been formed of Fe-based sintered metal or synthetic resin.
Here, the rack guide made of Fe-based sintered metal has sufficient mechanical strength against the impact load received from the rack bar, but has a large sliding friction resistance, so that the efficiency of the entire steering device is reduced, There was a possibility that the operability would be degraded.
On the other hand, a rack guide made of a synthetic resin has a small sliding friction resistance, so that the efficiency of the entire steering device can be improved, but the mechanical strength against an impact load received from the rack bar is inferior. In addition, there is a possibility that the durability of the entire steering device may be affected.

Therefore, as means for solving these problems, for example, a rack guide body formed of a metal member such as an Fe-based sintered metal or an aluminum alloy, and a surface covered with a synthetic resin layer, There is known a technique relating to a rack guide formed by a sliding plate piece fixed to a rack.
More specifically, the conventional rack guide is composed of a rack guide body having a hole at the center and a slide plate piece also having a protrusion at the center, and The sliding plate piece is fixed to the rack guide body by press-fitting the protrusion of the sliding plate piece (for example, see Patent Document 1).

JP 2013-28285 A

Here, in the conventional rack guide, the synthetic resin layer is formed of a porous sintered layer adhered to the surface of the sliding plate piece and the porous sintered layer while filling the pores of the porous sintered layer. And a resin layer coated on the surface of the layer.
Therefore, in such a synthetic resin layer, a region of only the resin layer exists on the surface of the porous sintered layer, and the surface of the synthetic resin layer wears relatively quickly.
As a result, the arrangement position of the rack guide is immediately displaced toward the rack bar side, so that the pressing force of the rack guide by the coil spring also fluctuates. It was difficult to maintain.

  The present invention has been made in view of the current problems described above, and supports a rack bar that meshes with a pinion pivotally supported by a gear case via rack teeth so as to be movable in the axial direction. A rack guide and a rack and pinion type steering device including the rack guide, wherein the rack guide can stably and firmly maintain a rack bar supported by the rack guide and a rack and pinion type steering device including the rack guide. It is an object to provide a device.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

That is, the rack guide according to claim 1 of the present invention is a rack guide that supports a rack bar that meshes with a pinion supported by a gear case via rack teeth so as to be movable in the axial direction. The bar has a convex surface on the side opposite to the side where the rack teeth are formed, and a concave sliding support surface in slidable contact.The rack guide includes a rack guide body, and the rack guide body has forms the sliding support surface, the surface of the sliding support surface, minute projections constituting the front surface roughness is formed, the thickness of the high and comparable the minute projections The surface of the sliding support surface is covered with the resin coating film, and the apex of the convex portion is located on the surface of the resin coating film.

As described above, in the rack guide of the present invention, the vertices of the fine projections constituting the surface roughness of the sliding support surface are located so as to reach the surface of the resin coating film. Unlike the rack guide described above, there is no case where a region of only the resin layer exists on the surface of the resin coating film.
Therefore, progress of abrasion on the surface of the resin coating film can be suppressed as much as possible, and dislocation of the rack guide to the rack bar side due to abrasion is reduced. As a result, the fluctuation of the pressing force of the rack guide by the coil spring can be prevented as much as possible, and the stable and firm support of the rack bar by the rack guide can be maintained.
Also, as in a conventional rack guide, the hardness of the resin coating film may change abruptly between a region including only the resin layer and a region including fine protrusions constituting the surface roughness of the sliding support surface. Therefore, there is little change in friction (change in the degree of sliding) on the sliding support surface, and adjustment of the pressing force of the rack guide against the rack bar is easy.
Further, in the rack guide of the present invention, the sliding support surface formed directly on the rack guide main body is coated with the resin coating film. It is not necessary to separately provide a sliding plate piece that is fixed to the main body, so that not only the number of components can be reduced, but also, for example, the protrusion of the sliding plate and the hole of the rack guide body corresponding to the protrusion. It is not necessary to provide a process for forming the sliding guide and a process for press-fitting the protrusion of the sliding plate piece into the hole of the rack guide main body. The sliding support surface of the rack guide is covered with a hard coating. In this case, it is sufficient to reduce the manufacturing cost.

On the other hand, a rack and pinion type steering device according to a second aspect of the present invention includes the rack guide according to any one of the first to third aspects.

  As described above, the rack and pinion type steering apparatus of the present invention includes the rack guide of the present invention described above, whereby the rack guide can maintain a stable and firmly supported state of the rack bar by the rack guide. As a result, a highly durable device with less failure can be realized.

  The present invention has the following effects.

  That is, according to the rack guide and the rack and pinion type steering device including the rack guide of the present invention, the support state of the rack bar by the rack guide can be stably and firmly maintained.

BRIEF DESCRIPTION OF THE DRAWINGS Sectional drawing which showed the whole structure of the rack-and-pinion type steering apparatus provided with the rack guide which concerns on one Embodiment of this invention. The perspective view showing the composition of the rack guide concerning one embodiment of the present invention. It is a figure showing the composition of the slide support surface of the rack guide concerning one embodiment of the present invention, (a) is a sectional view showing the slide support surface of an unused state, and (b) shows predetermined use. Sectional drawing which showed the sliding support surface after a period passage. FIG. 3 is an enlarged side view showing a configuration of a sliding support surface in the rack guide according to the embodiment of the present invention. The sectional side view showing the whole composition of the rack pinion type steering device provided with the rack guide concerning another embodiment of the present invention. The perspective view showing the composition of the rack guide concerning another embodiment of the present invention. It is a figure which showed the structure of the sliding support surface of the rack guide which concerns on another embodiment of this invention, (a) is sectional drawing which showed the sliding support surface of an unused state, (b) is predetermined use. Sectional drawing which showed the sliding support surface after a period passage.

  Next, embodiments of the invention will be described.

[Rack and pinion type steering device 1]
First, an overall configuration of a rack and pinion type steering device 1 (hereinafter, simply referred to as “steering device 1”) including a rack guide 6 that embodies the present invention will be described with reference to FIG.
In the following description, the vertical direction in FIG. 1 is defined as the vertical direction of the steering device 1 for convenience.
In FIG. 1, the direction of the arrow A is described as being defined in front of the steering device 1.

The steering device 1 in the present embodiment is, for example, a device for converting a rotation operation of a pinion 2 rotated by a steering wheel (not shown) into a straight-ahead operation of a rack bar 3.
The steering device 1 includes a gear case 4, and one end of the pinion 2 is inserted into the gear case 4, for example, forward (in the direction of arrow A in FIG. 1).

Here, pinion teeth 2 a are formed at one end of the pinion 2.
Then, inside the gear case 4, one end of the pinion 2 is pivotally supported via a pair of bearings 5 arranged with the pinion teeth 2 a interposed therebetween.

  The other end of the pinion 2 extends axially outside the gear case 4 and is connected to a steering wheel (not shown).

A rack bar 3 meshed with the pinion 2 is disposed inside the gear case 4.
A rack tooth 3a is formed on the outer peripheral surface of the rack bar 3 at the center in the axial center direction, and a rear surface of the rack bar 3 (a surface opposite to the side where the rack tooth 3a is formed) has a predetermined curvature. It is a convex surface 3b having a radius and having an arc shape in a sectional view.

  The rack bar 3 is disposed below the pinion teeth 2a so as to extend in a direction orthogonal to the pinion 2 in a plan view (for example, in the left-right direction in the present embodiment). Be engaged.

  Both ends of the rack bar 3 protrude from the inside of the gear case 4 to the outside, and the rack bar 3 slides in the axial direction (left-right direction) via a bearing member (not shown). Supported as possible.

On the lower surface of the gear case 4, a cylindrical projecting portion 4a is integrally formed.
The protruding portion 4a is formed at a position where the rack bar 3 is sandwiched between the pinion 2 and the inner peripheral portion (a space surrounded by the inner peripheral surface) of the rack bar 3. The rack guide 6, which is supported so as to be slidable, is slidably provided in the extending direction of the projecting portion 4a (in the present embodiment, the vertical direction).

  The rack guide 6 is urged toward the rack bar 3 by a compression coil spring 8 as an elastic member disposed between the rack guide 6 and a lid member 7 that closes a lower end of the protruding portion 4a.

  In the steering device 1 having the above-described configuration, when the pinion 2 is rotated around an axis via a steering wheel (not shown), the rotational driving force applied to the pinion 2 causes the pinion teeth to rotate. 2a and the rack teeth 3a are transmitted in this order, and are converted into the propulsion force of the rack bar 3 in the axial direction.

[Rack guide 6]
Next, the configuration of the rack guide 6 will be described in detail with reference to FIGS.
In the following description, the vertical direction in FIGS. 2 to 4 is defined as the vertical direction of the rack guide 6 for convenience.
2 and 4, the direction of the arrow A is defined as the front of the rack guide 6.

As shown in FIG. 1, the rack guide 6 presses the rack bar 3 engaged with the pinion 2 toward the pinion 2 while slidably supporting the rack bar 3 in the axial direction of the rack bar 3. It is a member.
The rack guide 6 is formed of, for example, a rack guide main body made of a columnar metal member such as an aluminum alloy, and has a sliding surface formed at one end thereof with a concave surface having a substantially arc-shaped cross-sectional view substantially the same as the convex surface 3 b of the rack bar 3. A support surface 6a is formed, and a cylindrical hollow portion 6b capable of holding the compression coil spring 8 is formed at the other end.

The rack guide 6 is disposed coaxially with the projecting portion 4a inside the gear case 4 with the sliding support surface 6a facing the rack bar 3 side. The other end of the compression coil spring 8 having one end fixed by the lid member 7 is held via the cylindrical hollow portion 6b.
Thus, the rack guide 6 contacts the convex surface 3b of the rack bar 3 via the sliding support surface 6a, and moves the inner peripheral portion of the protruding portion 4a through the outer peripheral surface 6c in the axial direction (in the present embodiment, (Up and down direction). At this time, the rack guide 6 is always urged toward the rack bar 3 by the compression coil spring 8.

Note that the sliding support surface 6a does not necessarily need to be formed with a constant radius of curvature, and may be formed with a changed curvature.
For example, as shown in FIG. 4, the sliding support surface 6 a of the rack guide 6 in the present embodiment is on one side (for example, in the present embodiment) with respect to a vertical center line C passing through the axis O of the rack bar 3. The first sliding support surface 6a1 is located in a region on the front side in the embodiment, and the second sliding support surface 6a2 is located in a region on the other side (for example, the rear side in the present embodiment). .

The first sliding support surface 6a1 passes through the axis O and is inclined forward by α1 ° with respect to the center line C, at a first center line C1 behind the axis O and at the first center line C1. It is formed in an arc shape with the upper point O1 as the center of curvature.
Here, α1 ° is an angle not exceeding αf ° (0 ° <α1 ° <αf °), and αf ° passes through the center line C, the front end of the sliding support surface 6a, and the axis O. This is the angle between the first virtual line L1.

On the other hand, the second sliding support surface 6a2 is at the front of the axis O and at the second center line C2 at the second center line C2 which passes through the axis O and is inclined α2 ° rearward with respect to the center line C. It is formed in an arc shape with the point O2 on the line C2 as the center of curvature.
Here, α2 ° is an angle not exceeding αb ° (0 ° <α2 ° <αb °), and αb ° passes through the center line C, the rear end of the sliding support surface 6a, and the axis O. The angle between the second virtual line L2 and the second virtual line L2.

In the first sliding support surface 6a1, an arc-shaped convex surface 3b, which is the outer peripheral surface of the rack bar 3, is circumscribed on the intersection D1 between the first center line C1 and the first sliding support surface 6a1. Is done.
In the second sliding support surface 6a2, an arc-shaped convex surface 3b, which is the outer peripheral surface of the rack bar 3, is circumscribed on an intersection D2 between the second center line C2 and the second sliding support surface 6a2. Is done.

As described above, the rack guide 6 according to the present embodiment has the center of curvature O1 and the center of curvature O2 at positions eccentric with respect to the axis O, respectively, and has the first sliding support surface 6a1 and the second sliding support surface having different radii of curvature. The rack bar 3 is supported at two points at the positions of the intersections D1 and D2 by the sliding support surfaces 6a composed of the two sliding support surfaces 6a2.
As a result, the sliding contact area between the sliding support surface 6a and the arc-shaped convex surface 3b of the rack bar 3 becomes a line or a narrow band, so that the sliding friction resistance with the rack bar 3 can be further reduced. it can.

  By the way, as shown in FIG. 2, in the present embodiment, the entire surface of the sliding support surface 6a of the rack guide 6, which can come into contact with the convex surface 3b of the rack bar 3, is coated with the resin coating film 10. I have to do that.

Here, the resin coating film 10 is a film coated for the purpose of reducing friction and improving abrasion resistance, and has a thickness of several μm to several tens μm (specifically, as described later, The thickness is approximately the same as the height of the fine projections constituting the surface roughness of the sliding support surface 6a.
The resin coating film 10 is composed of, for example, a binder resin and a solid lubricant, a binder resin and a hard material, or a binder resin, a solid lubricant and a hard material.

  Binder resin is mainly used as a binder, for example, polyamide imide resin, polyimide resin, epoxy resin, phenol resin, polyacetal resin, polyether ether Kent resin, polyphenylene sulfide resin polyamide, and elastomer At least one kind selected from among them can be used.

Solid lubricants are mainly used to reduce frictional resistance, have excellent conformability and non-seizure properties, and are contained in the binder resin in the form of fine powder.
The solid lubricant is selected from, for example, graphite, carbon, molybdenum disulfide (MoS ₂ ), polytetrafluoroethylene (PTFE), tungsten disulfide (WS ₂ ), boron nitride (h-BN), and SB203. At least one or more selected ones can be used.

The hard material is mainly used for improving abrasion resistance, and is made of a substance having a Vickers hardness greater than that of the rack guide 6. For example, when the rack guide 6 is made of an aluminum alloy (Vickers hardness HV 50 to 100), it is desirable to form a hard material with a material such as alumina (Vickers hardness HV 150).
Hard materials include, for example, silicon carbide (SiC), alumina (AlO ₃ ), titanium nitride (TiN), aluminum nitride (AlN), chromium dioxide (CrO ₂ ), silicon nitride (Si ₃ N ₄ ), and zirconium dioxide. At least one selected from (ZrO ₂ ) and iron phosphide (Fe ₃ P) can be used.

As described above, the resin coating film 10 is configured to include the binder resin and the solid lubricant and / or hard material contained in the binder resin.
Then, the rack guide 6 is covered with the resin coating film 10 on the entire surface of the sliding support surface 6a.

Specifically, as shown in FIG. 3A, countless fine projections 61 are formed on the surface of the sliding support surface 6a. The surface of the sliding support surface 6a is covered with the resin coating film 10 having a thickness substantially equal to the height of the convex portions 61.
In other words, in the present embodiment, the configuration is such that the vertices of the myriad of fine projections 61, 61... That constitute the surface roughness of the sliding support surface 6 a reach the surface of the resin coating film 10. For example, unlike a conventional rack guide, a region having only a resin layer hardly exists near the surface of the resin coating film 10.

Therefore, in the rack guide 6, when the use of the steering device 1 is started, countless convex portions 61 are immediately exposed on the surface of the resin coating film 10, and the resin coating film 10 is exposed. Has improved wear resistance.
As a result, as shown in FIG. 3B, even if a predetermined use period of the rack guide 6 has elapsed, the wear amount of the resin coating film 10 (dimension X shown in FIG. 3B). Can be reduced as compared with the conventional rack guide, and the progress of wear of the surface of the resin coating film 10 can be suppressed as much as possible.
Therefore, the arrangement position of the rack guide 6 is less likely to be displaced toward the rack bar 3 due to wear, and fluctuation of the pressing force of the rack guide 6 by the compression coil spring 8 is prevented as much as possible. It is possible to maintain a firm support state.

  Further, in the rack guide 6 of the present embodiment, as in the conventional rack guide, the resin coating is performed in a region including only the resin layer and a region including the fine protrusions constituting the surface roughness of the sliding support surface. Since the hardness of the coating does not change suddenly, there is little change in friction (change in the degree of sliding) on the sliding support surface 6a, and adjustment of the pressing force of the rack guide 6 against the rack bar 3 is easy.

Further, as shown in FIG. 2, in this embodiment, the sliding support surface 6a of the rack guide 6 (rack guide main body) is directly coated with the resin coating film 10.
Therefore, unlike the conventional rack guide, there is no need to separately provide a sliding plate piece fixed to the sliding support surface of the rack guide main body, and the number of components can be reduced.
Also, in a conventional rack guide manufacturing process, a process for drawing a projection in the center of a slide plate piece and a process for punching a hole corresponding to the projection in the rack guide body. In addition, steps for press-fitting the projections of the sliding plate pieces into the holes of the rack guide main body and the like were necessary, but these steps are performed in the manufacturing process of the rack guide 6 in the present embodiment. There is no necessity, and only the step of coating the sliding support surface 6a of the rack guide 6 with the resin coating film 10 is sufficient.
Therefore, according to the rack guide 6 in the present embodiment, it is possible to reduce the manufacturing cost.

  The position of the rack guide 6 is not limited to the present embodiment, and the rack guide 3 can be supported by pressing the rack bar 3 toward the pinion 2 via the sliding support surface 6a. It may be provided at any position along the axial direction of the bar 3.

[Rack guide 106 (another embodiment)]
Next, the configuration of a rack guide 106 according to another embodiment of the present invention will be described in detail with reference to FIGS.
In the following description, for convenience, the vertical direction in FIG. 5 is defined as the vertical direction of the rack-and-pinion type steering device 101 (hereinafter, simply referred to as “steering device 101”), and the vertical direction in FIGS. The vertical direction of the rack guide 106 is defined and described.
5 and 6, the direction of arrow A is defined as forward.

The rack guide 106 in another embodiment has a configuration substantially the same as the rack guide 6 described above, but differs from the rack guide 6 in that a slide plate 161 is provided.
Therefore, in the following description, mainly the differences from the rack guide 6 will be described, and the description of the configuration equivalent to the rack guide 6 will be omitted.

As shown in FIG. 5, the rack guide 106 is used to support the rack bar 103 engaged with the pinion 102 slidably in the axial direction of the rack bar 103 while pressing the rack bar 103 toward the pinion 102. It is a member.
The rack guide 106 includes a slide plate 161 that is in contact with the convex surface 103b of the rack bar 103, a rack guide body 162 to which the slide plate 161 is attached, and the like.

The slide plate piece 161 is made of, for example, an Fe-based metal member, and has a concave surface 161 a having a substantially arc-shaped cross-sectional view substantially the same as the convex surface 103 b of the rack bar 103.
In the center of the slide plate 161, a protruding portion 161 b protruding on the side opposite to the concave surface 161 a side is formed by, for example, press drawing.

On the other hand, the rack guide body 162 is formed of a columnar metal member made of, for example, an Fe-based sintered metal, an aluminum alloy, or the like, and has one end formed in an arc shape in a sectional view along the sliding plate piece 161. A formed plate piece supporting surface 162a is formed, and a cylindrical hollow portion 162b capable of holding the compression coil spring 108 is formed at the other end.
In addition, a groove 162c having substantially the same shape as the protruding portion 161b of the sliding plate 161 is formed at the center of the plate supporting surface 162a.

At one end of the rack guide main body 162, the sliding plate 161 is disposed via a plate supporting surface 162a. At this time, the protrusion 161b of the sliding plate 161 is inserted into the groove 162c of the plate supporting surface 162a.
Thus, the sliding plate 161 is firmly held at one end of the rack guide body 162.

  The rack guide 106 having such a configuration is disposed coaxially with the housing portion 104a inside the gear case 104, with the concave surface 161a of the sliding plate 161 facing the rack bar 103 side. The other end of the compression coil spring 108, one end of which is fixed by the lid member 107, is held via the cylindrical hollow portion 162 b of the rack guide body 162.

Thus, while the rack guide 106 is in contact with the convex surface 103b of the rack bar 103 via the concave surface 161a of the slide plate piece 161, the rack guide 106 pivots the inner peripheral portion of the housing portion 104a via the outer peripheral surface 162d of the rack guide body 162. It is disposed so as to be slidable in the center direction (in the present embodiment, the vertical direction). That is, in the rack guide 106, the concave surface 161 a of the sliding plate 161 is provided as a “sliding support surface” that is directly contacted when slidingly supporting the rack bar 103.
At this time, the rack guide 106 is constantly urged toward the rack bar 103 by the compression coil spring 108.

  By the way, as shown in FIG. 6, in the present embodiment, the sliding support surface of the rack guide 106 (more specifically, the concave surface 161 a of the sliding plate piece 161) which can come into contact with the convex surface 103 b of the rack bar 103. Is to be coated with the resin coating film 110 on the entire surface.

Specifically, as shown in FIG. 7A, the surface of the concave surface 161a (sliding support surface) of the sliding plate piece 161 has a porous sintered layer 163 made of, for example, copper-based metal powder. Is formed, and the surface of the porous sintered layer is coated with the resin coating film 110 while filling the pores of the porous sintered layer.

Here, the thickness of the resin coating film 110 is set to be substantially the same as the height of the countless fine projections 163 a forming the porous sintered layer 163.
In other words, in the present embodiment, the apexes of the myriad of fine projections 163a, 163a,... Constituting the surface roughness of the concave surface 161a (sliding support surface) of the sliding plate piece 161 are formed of resin coating films. It is configured to reach the surface of the resin coating 110, and, for example, unlike a conventional rack guide, a region of only the resin layer hardly exists near the surface of the resin coating film 110.

Therefore, in the rack guide 106, when the use of the steering device 101 is started, the countless convex portions 163a, 163a,... Are immediately exposed on the surface of the resin coating film 110. Has improved wear resistance.
As a result, as shown in FIG. 7B, even when a predetermined use period of the rack guide 106 has elapsed, the amount of wear of the resin coating film 110 (dimension Y shown in FIG. 3B). Can be reduced as compared with the conventional rack guide, and the progress of wear of the surface of the resin coating film 110 can be suppressed as much as possible.
Therefore, the arrangement position of the rack guide 106 is less likely to be displaced toward the rack bar 103 due to wear, and fluctuation of the pressing force of the rack guide 106 by the compression coil spring 108 is prevented as much as possible, and the rack bar 106 is stabilized by the rack guide 106. It is possible to maintain a firm support state.

  Further, in the rack guide 106 of the present embodiment, unlike the conventional rack guide, the resin coating is performed in a region including only the resin layer and a region including the fine protrusions constituting the surface roughness of the sliding support surface. Since the hardness of the coating does not change rapidly, there is little friction change (change in the degree of sliding) on the concave surface 161a (sliding support surface) of the sliding plate piece 161 and the rack guide 106 is pressed against the rack bar 103. Adjustment of force is also easy.

Further, in the present embodiment, the rack guide 106 is constituted by a rack guide body 162 and a slide plate 161 fixed to one end of the rack guide body 162 like a conventional rack guide. The concave surface 161a (sliding support surface) formed on the plate piece 161 is coated with the resin coating film 110.
Thus, for example, the same function as that of the rack guide 106 of the present embodiment as described above can be added to the existing rack guide without any special modification.

DESCRIPTION OF SYMBOLS 1 Rack pinion type steering device 2 Pinion 3 Rack bar 3a Rack tooth 3b Convex surface 4 Gear case 6 Rack guide 6a Sliding support surface 10 Resin coating film 61 Convex portion 101 Rack pinion type steering device 102 Pinion 103 Rack bar 103b Convex surface 104 Gear case 106 Rack guide 110 Resin coating film 161 Sliding plate piece 161a Concave surface (sliding support surface)
162 Rack guide body 163 Porous sintered layer 163a Convex part

Claims (2)

A rack guide that supports a rack bar that meshes via a pinion and rack teeth that are pivotally supported by a gear case so as to be movable in an axial direction,
A convex surface on the side opposite to the side on which the rack teeth are formed in the rack bar, having a concave sliding support surface that is slidably contacted,
The rack guide includes a rack guide body,
Forming the sliding support surface on the rack guide body;
On the surface of the sliding support surface, fine projections constituting surface roughness are formed,
The surface of the sliding support surface is covered with a resin coating film having a thickness corresponding to the depth of the void formed by the convex portion and having a film thickness capable of filling the void of the convex portion,
The resin coating film has a binder resin, a solid lubricant and / or a hard material contained in the binder resin,
When the rack guide is not used,
The convex portion is have a site to expose the vertices on the surface of the resin coating film,
A rack guide, characterized in that: A rack guide according to claim 1 is provided.
A rack-and-pinion steering device, characterized in that:

Images