JP2020085106A - Automobile component and manufacturing method of the same - Google Patents

Abstract

To provide an automobile component which has high slidability and can be formed easily, and to provide a manufacturing method of the automobile component.SOLUTION: An automobile component 11 of the present invention includes: a slide member 2 having a sliding surface 3; and a resin coating part 14 which is formed in at least a part of the sliding surface 3. The resin coating part 14 has a cut surface and/or a ground surface 17a. The resin coating part 14 has: a smooth part 16 in which a thickness is uniform; and a cutting part and/or a grinding part 17 formed continuously from the smooth part 16 and including the cut surface and/or the ground surface 17a. A maximum film thickness in the cutting part and/or the grinding part 17 may be smaller than or equal to a maximum film thickness of the smooth part 16. The cutting part and/or the grinding part 17 may be formed in at least a part of a peripheral edge part of the resin coating part 14.SELECTED DRAWING: Figure 3

Description

The present invention relates to an automobile part having high slidability and a method for manufacturing the same.

A coating layer is usually formed on the sliding surface of the sliding member for the purpose of improving slidability and protecting the member. For example, Japanese Patent No. 5997246 (Patent Document 1), Japanese Patent No. 4599892 (Patent Document 2), and the like disclose a molded product in which a resin coating layer having a predetermined shape is formed on a sliding surface of a sliding member. There is. Such a resin coating layer is usually formed of a polyamide-imide resin composition containing a solid lubricant such as molybdenum disulfide.

However, although such a resin coating layer shows a certain degree of slidability, since a resin varnish having a high viscosity is used during molding, it is difficult to improve the surface smoothness of the resin coating layer and the slidability is not sufficient.

In addition, WO 2017/081963 (Patent Document 3) discloses a curable liquid composition containing a predetermined bifunctional alicyclic epoxy compound as a surface treatment kit for treating the surface of a molded body formed of a metal. A surface treatment kit including the product (A) and a liquid composition (B) containing a polyamide-imide resin is disclosed. In the examples of this document, the liquid composition (B) is applied onto an aluminum plate to form a primer layer, and a predetermined bifunctional alicyclic epoxy compound, a curing agent and a leveling agent are applied onto the primer layer. The curable liquid composition (A) containing is applied to form a top coat layer. Further, this document describes that by adding a leveling agent or the like to reduce the surface tension of the treatment liquid, surface smoothness can be improved and slidability can be improved.

However, even if the resin coating layer is formed by the surface treatment kit described in Patent Document 3, the slidability may not be sufficiently improved for some reason.

Japanese Patent No. 5997246 ([0010][0025] to [0027][0030], FIG. 8) Japanese Patent No. 4599892 ([0034] to [0038], FIG. 3) International Publication No. 2017/081963 (Claims, [0059], Examples)

Therefore, an object of the present invention is to provide an automobile part (or a molded body) which has high slidability and can be easily formed, and a manufacturing method thereof.

Another object of the present invention is to provide an automobile part in which a lubricating oil (or oil) is used in a sliding member, in which uneven distribution of the lubricating oil is reduced, and a fluid resistance of the lubricating oil is reduced, and a manufacturing method thereof. is there.

As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that when a resin coating portion is formed on a sliding surface using a resin composition having low surface tension and/or viscosity, a resin having a relatively high viscosity in the related art is used. Surprisingly, although the surface smoothness can be improved compared to the composition, it is not always possible to form a uniform film thickness, that is, the resin coating part has a large film thickness (or an abnormal film thickness). Part) may exist partially around the edge.

Specifically, the present inventors have found that the curable liquid composition (A) described in Patent Document 3; or a curable composition (B) that can adhere to a metal substrate or the like without forming a primer layer [specifically Include alicyclic epoxy compounds such as 3,4,3′,4′-diepoxybicyclohexyl, saturated aliphatic glycidyl ether type epoxy compounds such as 1,4-butanediol diglycidyl ether, and 3-ethyl. Curable composition containing a polymerizable compound having a hydroxyl group such as 3-hydroxymethyl oxetane and 4-hydroxybutyl vinyl ether, a leveling agent such as a silicone-based leveling agent, and a polymerization initiator] A resin coating portion was formed using the coating agent (or curable composition), and the film thickness in the vicinity of the end portion was measured. FIG. 1 shows an example of measurement results when the curable composition (B) was used. As is clear from FIG. 1, in the resin coating portion formed by using the low-viscosity coating agent, a thick film portion having a large film thickness is partially formed at the end portion.

Normally, in the sliding state, a predetermined gap (clearance or gap) is provided between the sliding surface of the sliding member and the sliding mating member facing the sliding surface. And a resin coating portion having an appropriate film thickness is formed. Therefore, it has been found that in the thick film portion, it is difficult to secure the clearance required for sliding, the contact resistance increases, and the slidability may not be sufficiently improved. In particular, in the case of a sliding member such as a skirt portion (piston skirt portion) of a piston member that requires precise size control, it is more difficult to secure a clearance with the cylinder liner because of the thick film portion, and contact resistance is increased. Easy to grow. Further, since the thick film portion blocks the lubricating oil, the lubricating oil may be unevenly distributed to increase the fluid resistance and further reduce the slidability. Therefore, it was found that even if the central portion or the inner surface of the resin coating portion is smoothed by the low-viscosity coating agent, the slidability improving effect may not be sufficiently obtained.

As a result of further diligent studies, the present inventors have found that an automobile part having high slidability can be produced by a simple method of forming a cutting surface and/or a grinding surface on a resin coating portion. Was completed.

That is, the automobile part of the present invention is an automobile part including a sliding member having a sliding surface and a resin coating portion formed on at least a part of the sliding surface, wherein the resin coating portion is a cutting surface. And/or has a ground surface.

The resin coating portion has a smooth portion having a uniform thickness and a cutting surface and/or a grinding surface formed continuously with the smooth portion (or extending at least from the end portion of the smooth portion toward the sliding member). It may have a cutting part and/or a grinding part including it. The maximum film thickness of the cutting part and/or the grinding part may be equal to or less than the maximum film thickness of the smooth part. The cutting portion and/or the grinding portion may be formed on at least a part of a peripheral portion of the resin coating portion. The film thickness of the cutting portion and/or the grinding portion may be formed to be smaller as it goes away from the smooth portion (or the end portion of the smooth portion) (or toward the end portion of the non-contact portion or the resin coating portion).

The arithmetic mean roughness Ra ₁ of the surface of the smooth portion measured according to JIS B0601 (2001) may be 0.2 μm or less, and the arithmetic mean roughness Ra ₂ of the cutting surface and/or the grinding surface is the above. It may be Ra ₁ or more. The sliding surface may be at least curved. The resin coating portion may cover the sliding member at an area ratio of 80% or more with respect to the entire sliding surface. The sliding member may be made of a metal material.

The resin coating portion (surface or surface layer of the resin coating portion) may be formed at least by a cured product of a curable composition containing a curable resin, and the viscosity of the curable composition at 25° C. is 200 mPa· It may be s or less.

The automobile part may be a piston. In such automobile parts, the resin coating portion formed on the skirt portion as a sliding surface is a perfect circle or an ellipse on the surface of the resin coating portion on the surface orthogonal to the direction in which the piston slides in the cylinder. A surface of a smooth portion extending along the track, and a cutting surface and/or grinding extending from the end of the smooth portion to the skirt side at an angle greater than 0° with respect to the tangent of the track at the end. May have a surface.

The present invention includes a resin coating step of coating a resin on a sliding surface of a sliding member to form a resin coating portion, and a processing step of cutting or grinding the resin coating portion to form a cutting surface and/or a ground surface. Also included is a method of manufacturing the automobile part including the above.

In the present specification and claims, the “alicyclic epoxy group” means that an aliphatic ring (for example, cycloalkane ring such as cyclohexane ring) and an oxirane ring (or epoxide) are adjacent to each other. It means a group having at least a skeleton condensed in a form sharing one carbon atom.

The automobile part of the present invention has a resin coating portion having a cutting surface and/or a grinding surface, and thus has high slidability and can be easily formed. A piston member that uses lubricating oil (or oil) has a cutting surface and/or a grinding surface, so uneven distribution of the lubricating oil is reduced (or the lubricating oil easily spreads), and the fluid resistance of the lubricating oil is reduced. It can be expected to have an effect.

FIG. 1 is a graph showing a film thickness in the vicinity of an end portion of a resin coating portion formed of a low-viscosity coating agent. FIG. 2 is a partial schematic sectional view showing an example of a conventional automobile part. FIG. 3 is a partial schematic sectional view showing an example of the automobile part of the present invention. FIG. 4 is a partial schematic sectional view showing another example of the automobile part of the present invention. FIG. 5 is a partial schematic sectional view showing still another example of the automobile component of the present invention. FIG. 6 is a graph (vertical axis/horizontal axis ratio=1/1000) showing the surface shape of an automobile component (or a resin coating portion) before cutting obtained in Example 1. FIG. 7 is a graph (vertical axis/horizontal axis ratio=1/1000) showing the surface shape of the automobile part (or resin coating part) after cutting obtained in Example 1. FIG. 8 is a schematic diagram showing the automotive pistons obtained in Examples 2 and 3.

Hereinafter, the molded articles of the related art and the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a partial schematic sectional view showing an example of a conventional automobile part. A conventional automobile part 1 shown in FIG. 2 has a sliding member 2 having a curved sliding surface 3 and a resin coating portion 4 formed on at least a part of the sliding surface 3. A thick film portion (or abnormal film thickness portion) 5 having a large film thickness is formed on the peripheral portion of the resin coating portion 4.

Such a thick film portion 5 is not seen in the case where the resin coating portion is formed of a resin composition having a relatively high viscosity including the above-mentioned polyamide-imide resin, and the slidability (or surface smoothness) is further improved. It was confirmed when a resin composition having a low viscosity and/or a low surface tension was used for the purpose. It is generally considered that a resin composition having a lower viscosity is more likely to form a coating portion having a smooth surface and a uniform film thickness, while a resin composition (or coating agent) having a lower viscosity is used. Then, probably due to the influence of the surface tension of the coating agent, a thick film portion (or an abnormal film thickness portion) 5 was found in the vicinity of the end portion (or peripheral portion) of the resin coating portion 4.

For example, in the case of a piston member, even if such a problem occurs, the curved surface shape of the end portion of the piston member (skirt portion), which is the base material, is largely bent (curved) in advance for the thick film portion, If sufficient clearance is secured with the liner, sufficient clearance can be maintained even after the resin coating portion is formed. However, when the smoothness of the surface of the resin coating portion as seen in the present invention is very high (or when a low-viscosity coating agent is used), it is assumed that sliding movement is performed by surface contact such as a piston member. , The abnormal film thickness near the edge becomes a groove for the lubricating oil sump (or prevents the lubricating oil from spreading), and the effect of reducing friction (or improving slidability) by forming a smooth sliding surface is sufficient. Can't get to.

On the other hand, in the automobile part of the present invention, the thick film portion is contacted by the simple method of cutting and/or grinding (or polishing) the thick film portion to form a cut surface and/or a ground surface. The increase in resistance can be suppressed and the slidability can be greatly improved. In addition, due to the inclination of the cutting surface and/or the grinding surface, excess lubricating oil on the surface of the resin coating portion is made to flow ( The effect of reducing the flow resistance of the lubricating oil and improving the slidability can be expected without restricting the flow of the lubricating oil).

Specific examples of the automobile part of the present invention include the examples shown in FIGS. 3 to 5 in which the thick film portion 5 in the example of FIG. 2 is cut and/or ground. In the drawings described below, the same or common elements as those in FIG. 2 are designated by the same reference numerals, and unless otherwise specified, they are the same as the embodiment shown in FIG. 2 (hereinafter the same). ..

FIG. 3 is a partial schematic sectional view showing an example of the automobile part of the present invention. This automobile part 11 is a resin coating portion that is coated on the sliding surface 3 that is curved in the circumferential direction of the sliding member 2 (or in the direction perpendicular to the sliding direction) and that can contact the sliding mating material. 14 and a non-contact portion (or a non-sliding portion or a non-coating portion) 18 that is exposed to the sliding surface 3 and cannot contact the sliding mating member in the sliding state. The resin coating portion 14 is formed with a smooth portion 16 having a uniform thickness, and formed continuously with the smooth portion 16 [or from the end portion (cutting start portion or boundary portion) of the smooth portion 16 to the sliding member 2 side (or The cutting surface and/or the grinding portion 17 includes a cutting surface and/or a grinding surface 17a that is formed to extend to the non-contact portion 18 side). The cutting portion and/or the grinding portion 17 is formed by cutting and/or grinding the thick film portion 5.

In the present specification and claims, "cutting surface and/or grinding surface" and "cutting portion and/or grinding portion" having these surfaces are simply referred to as "cutting surface" and "cutting portion". They may be called respectively.

In this example, the film thickness of the cutting portion 17 is formed so as to decrease from the end portion of the smooth portion 16 to the end portion (the outer edge portion of the cutting portion 17 or the non-contact portion 18) of the resin coating portion 14. In other words, a predetermined portion of the resin coating portion 14 (or the end portion of the smooth portion 16) is used as a cutting start portion (or boundary portion) to cut the side portion (edge portion, peripheral portion or end portion) of the resin coating portion 14. The cutting portion 17 having the cutting surface 17a inclined toward the sliding surface 3 side is formed. That is, the cutting surface 17a forms a predetermined angle θ (or an inclination angle) with respect to a straight line (indicated by a dotted line in the drawing) extending from the end of the smooth portion 16 in a direction perpendicular to the thickness direction of the end. θ, θ>0°) and extend (or incline) to the sliding surface 3 side.

This inclination angle θ gradually changes as it moves away from the end of the smooth portion 16 (or toward the end of the non-contact portion 18 or the resin coating portion 14). Therefore, the thickness of the cutting portion 17 is reduced by the cutting surface 17a which is continuous with the end portion of the smooth portion 16 and extends with a relatively small angle θ (for example, about 0.1 to 10°). Or gradually decrease). In this example, both cutting surfaces 17a are curved (or curved) and extend.

By forming the resin coating portion 14 in such a form, the maximum film thickness of the cutting portion 17 becomes less than or equal to the maximum film thickness of the smooth portion 16, and the thick film portion 5 in FIG. Sliding property can be improved without raising.

FIG. 4 is a partial schematic sectional view showing another example of the automobile part of the present invention. This example is different from the example of FIG. 3 mainly in that a non-contact portion where the sliding surface 3 is exposed is not formed.

That is, in this automobile part 21, the resin coating portion 24 is formed on the curved sliding surface 3, and the resin coating portion 24 has a smooth portion 26 having a uniform thickness and an end portion of the smooth portion 26 ( The cutting portion 27 includes a cutting surface 27a that is formed by linearly extending from the cutting start portion or boundary portion toward the end portion of the sliding surface 3. The inclination angle θ in this example is substantially constant, and the cutting surface 27a is formed by a cutting surface extending at a relatively small inclination angle θ (for example, about 0.1 to 3°).

Even in such a configuration, the maximum film thickness of the cutting portion 27 is equal to or less than the maximum film thickness of the smooth portion 26, so that the slidability can be improved without increasing the contact resistance. That is, the non-contact portion does not necessarily have to be formed as long as the thick film portion having a film thickness larger than the maximum film thickness of the smooth portion 26 can be removed.

FIG. 5 is a partial schematic sectional view showing still another example of the automobile component of the present invention. In this example, mainly in the non-contact portion (or non-sliding portion) 38 where the sliding surface 3 is exposed, a protrusion (or a convex portion) 38a is formed as a residue by cutting and/or grinding. 3 is different from the example.

That is, the automobile part 31 includes the resin coating portion 34 and the non-contact portion (or non-sliding portion) 38 on the curved sliding surface 3; the resin coating portion 34 has a uniform thickness. Smooth part 36 and a cutting surface formed continuously with the end (or cutting start part) of the smooth part 36 (or extending in a curvilinear inclination from the end toward the sliding member 2 side) The non-contact portion 38 is formed with a protrusion (or a protrusion) 38a having a height (or film thickness) lower than the maximum film thickness of the smooth portion 36 (or It remains).

The cutting portion 37 and the cutting surface 37a thereof in this example are formed by an inclined cutting portion like the cutting portion 17 and the cutting surface 17a in FIG.

Even in such a configuration, since the maximum film thickness of the cutting portion 37 and the protruding portion 38a is equal to or less than the maximum film thickness of the smooth portion 36, the slidability can be improved without increasing the contact resistance. That is, as long as the thick film portion having a film thickness larger than the maximum film thickness of the smooth portion 36 can be removed, it is not necessary to completely remove the protruding portion 38a. Therefore, the cutting and/or grinding is performed by a simple (or rough) method to some extent. May be.

[Resin coating part]
In the automobile part of the present invention, the resin coating portion is formed on at least a part of the sliding surface of the sliding member, and may cover almost the entire sliding surface, or may cover a part thereof ( For example, a pattern shape such as a stripe shape or a polka dot pattern may be formed). Usually, since the thick film portion is easily formed in the peripheral edge portion (outer edge portion, edge portion or end portion) of the resin coating portion, from the viewpoint of suppressing peeling of the resin coating portion due to cutting while reducing the labor of cutting, It is preferable that the resin coating portion is formed with as few edge portions as possible, and it is particularly preferable that the pattern shape is not formed.

The area ratio (or coating ratio) of the resin coating portion can be selected from the range of, for example, 10% or more (for example, 30% or more) with respect to the entire sliding surface, and for example, 50% or more (for example, 60 to 100). %), preferably 70% or more (eg 75 to 98%), more preferably 80% or more (eg 85 to 95%). Further, the ratio may be substantially 100% (a mode in which the non-contact portion is not formed) as in the mode in FIG. If the area ratio of the resin coating portion is too small, the sliding member may not be sufficiently protected and the slidability may not be improved.

The resin coating portion has at least a cutting surface. Usually, the resin coating portion includes a smooth portion having a uniform thickness and a cutting portion including a cutting surface continuous with the smooth portion (or extending from the end portion of the smooth portion to be inclined toward at least the sliding member). And have. The ratio of the total area of the surface of the smooth portion to the total area of the cutting surface can be appropriately selected according to the shape and size of the sliding surface and the resin coating portion, for example, the former/the latter=50/50 to 99.9. /0.1 (for example, 60/40 to 99.5/0.5), preferably 70/30 to 99/1 (for example, 80/20 to 98/2), and more preferably 85/15 to 97/. It may be about 3 (for example, 90/10 to 95/5).

The position of the cutting portion is not particularly limited, but since the thick film portion is often formed in the vicinity of the peripheral edge portion (outer edge portion, edge portion or end portion) of the resin coating portion, the cutting portion is not limited to the resin coating portion. It is often formed on at least a part of the peripheral portion.

The maximum film thickness of the cut portion is usually formed to be equal to or less than the maximum film thickness of the smooth portion. In the sliding state, the cut portion thus formed does not substantially come into contact with the opposite sliding mating member, so that the slidability can be greatly improved without increasing the contact resistance. Therefore, when the cutting portion is formed on the peripheral portion of the resin coating portion, the film thickness of the cutting portion becomes [from the end portion of the smooth portion to the end portion of the resin coating portion as the distance from the smooth portion (or the end portion of the smooth portion) increases. (As it goes to the outer edge of the cutting part or the non-contact part side), it is formed large in the middle [larger within the range not exceeding the maximum film thickness of the smooth part (for example, a form in which a protrusion is formed on the cutting part)] However, it is often formed small.

In the cross section parallel to the thickness direction of the resin coating part (or the cross section perpendicular to the sliding direction), the shape of the cutting part is, for example, extending from the end of the smooth part in the direction perpendicular to the thickness direction of this end. A shape inclined with respect to a straight line at an angle θ; a step shape or a step shape (a shape in which the angle θ includes approximately 0° and/or approximately 90°) and the like can be mentioned. The cutting portion may be formed of these shapes alone or in combination of two or more kinds. Of these shapes, in many cases, at least a shape that inclines at an angle θ is included.

In the cutting portion, the angle θ is not particularly limited, and may be selected from the range of more than 0° and 90° or less, specifically, more than 0° and 20° or less (for example, 0. 01 to 10°), preferably 0.1 to 5° (for example, 0.2 to 3°), and more preferably about 0.5 to 1°. Because of the relationship between the film thickness of the resin coating portion (or coating film) and the cutting width, etc., the angle θ is usually a relatively gentle angle, and therefore, for example, exceeds 0° and is 5° or less (for example, 5° or less). , 0.05-4°), preferably 0.1-2.5° (eg 0.15-0.5°), more preferably 1-2° (eg 1.2-1.8°). ) Often about. The inclination angle θ may be constant over the entire cutting portion (inclined linearly) or may vary depending on the portion of the cutting portion (for example, curved or curved while inclining, linearly inclined). It may be inclined and bent in the middle, a combination of a linear inclination and a curved inclination, etc.), and usually varies depending on the part of the cutting portion. In the present invention, the slidability can be effectively improved even if the angle θ is gently formed by slight cutting.

Specifically, as the form of the cut portion, as it goes away from the end portion of the smooth portion [or as it goes to the end portion of the cut portion or the resin coating portion] (hereinafter the same), for example, cut portion/projection portion/cut portion in this order. Examples include a continuous form and a form formed by the cutting portion alone.

Although not necessarily required, the cutting portion and/or the non-contact portion may be provided with a projection (projection) that is bent or curved in the thickness direction of the resin coating portion to project. The protrusion is usually formed (or remains) as a residue due to cutting. The maximum height (or film thickness) of such a protruding portion is formed to be equal to or less than the maximum film thickness of the smooth portion, and in the sliding state, there is substantially no contact with the opposite sliding mating member, so contact It does not increase resistance. That is, even if such protrusions are left by cutting, the slidability can be improved if only the thick film portion can be removed. Therefore, the productivity may be improved by making a slight cut.

One or a plurality of protrusions may be formed, and when a plurality of protrusions are formed, they may be regularly and/or irregularly formed. Further, the protrusion may be in a form of forming a ridge (ridge) in a linear shape or a curved shape (or curved).

The average film thickness of the smooth portion can be appropriately selected according to the form and application of the sliding member, and can be selected from the range of, for example, 1 to 500 μm (for example, 2 to 200 μm), for example, 2 to 100 μm (for example, 3 to 50 μm), preferably 5 to 40 μm (for example, 8 to 30 μm), more preferably about 10 to 25 μm (for example, 15 to 20 μm), and usually 12 to 35 μm (for example, 15 to 30 μm). It may be a degree. If the average film thickness is too thin, the slidability and rigidity may decrease. The film thickness of the smooth portion can be measured by the method described in Examples below.

The arithmetic average roughness Ra ₁ on the surface of the smooth portion is, for example, 1 μm or less (for example, 0.001 to 0.5 μm), preferably 0.2 μm or less (for example, 0.001 to 0.18 μm), and more preferably 0. 0.15 μm or less (for example, 0.01 to 0.12 μm), more preferably 0.1 μm or less (for example, 0.02 to 0.08 μm), and particularly 0.05 μm or less (for example, 0.025 to 0.04 μm). It may be a degree. If the arithmetic average roughness Ra ₁ is too large, the surface smoothness may be lowered and the slidability may be lowered.

The arithmetic average roughness Ra ₂ on the cut surface is usually more than or equal to the arithmetic average roughness Ra _{1 of the} smooth surface because the coating surface is likely to be rough due to cutting, and for example, 0.1 to 10 μm ( For example, 0.15 to 5 μm), preferably 0.2 to 1 μm (for example, 0.25 to 0.8 μm), and more preferably 0.27 to 0.5 μm (for example, 0.3 to 0.4 μm). May be In the present specification and claims, the arithmetic mean roughness Ra can be measured according to JIS B0601 (2001).

A typical example of the automobile part of the present invention is a piston. The resin coating portion in such an automobile part is formed on a skirt portion (or piston skirt portion) as a sliding surface in a cross-sectional direction perpendicular to the direction in which the piston slides in the cylinder. More specifically as such a form of the resin coating portion, in the cross-sectional direction, from the surface of the smooth portion extending along the trajectory of a perfect circle or an ellipse on the surface of the resin coating portion, and from the end of the smooth portion, The skirt at an angle θ (for example, 0.1 to 90°, preferably 0.2 to 45°, more preferably 0.5 to 10°) larger than 0° with respect to the tangent line of the orbit at this end portion. It may have a cutting surface extending to the part side.

The resin coating portion can be formed by using a resin composition containing a resin, and the thick film portion in the resin coating portion tends to be generated as the resin composition has higher fluidity (lower viscosity). Therefore, the viscosity of the resin composition (eg, curable composition) at a temperature of 25° C. can be selected from the range of, for example, about 200 mPa·s or less (eg, 0.1 to 180 mPa·s), for example, 150 mPa·s. s or less (for example, 1 to 120 mPa·s), preferably 100 mPa·s or less (for example, 10 to 80 mPa·s), and more preferably about 60 mPa·s or less (for example, 15 to 50 mPa·s). .. When the viscosity of the resin composition is too high, not only the surface smoothness cannot be improved, but also the slidability improving effect may not be sufficiently exhibited. In addition, in the present specification and claims, the viscosity can be measured by a method described in Examples described later.

The resin coating portion may be formed by using a coating agent (or resin composition) containing a thermoplastic resin, but normally, a coating agent (or curable composition) containing a curable resin (heat or photocurable resin) is used. In many cases, at least the surface of the resin coating is formed by the cured product of this curable composition. Examples of the curable resin include epoxy compounds such as alicyclic epoxy compounds having an alicyclic epoxy group, vinyl ether compounds, and polymerizable compounds such as oxetane ring-containing compounds. These polymerizable compounds may have a hydroxyl group and may be used alone or in combination of two or more kinds. From the viewpoint of adhesion, it is preferable to combine an epoxy compound, a vinyl ether compound and an oxetane ring-containing compound. From the viewpoint of slidability, hardness, heat resistance, etc., it often contains at least an alicyclic epoxy compound (in particular, an alicyclic epoxy compound represented by the formula (1) described in Patent Document 3).

The curable composition may contain a conventional additive such as a leveling agent (for example, the leveling agent described in Patent Document 3, particularly a silicone-based leveling agent), a polymerization initiator, or a conventional solvent.

Further, the resin coating portion, as long as at least the surface is formed of a cured product of the curable composition having a low viscosity, if necessary, between the top coat layer and the sliding surface formed of the cured product A primer layer may be included to intervene between them and improve the adhesion. The composition for forming a primer layer for forming the primer layer is not particularly limited, and examples thereof include a liquid composition (B) containing a polyamideimide resin described in Patent Document 3 and the like. The viscosity of the primer layer forming composition is not particularly limited.

[Sliding member]
The sliding member in the automobile part of the present invention is not particularly limited as long as it can form a resin coating portion and has at least a sliding surface that faces a sliding mating member in a sliding state, and has various shapes. The effect of improving the slidability of parts can be exhibited. Therefore, the sliding surface may have either a planar shape or a curved shape (bent and/or curved shape), and it is particularly preferable that the sliding surface is at least curved. If the sliding surface has a curved shape, the resin composition tends to flow downward on the curved surface due to gravity when forming the resin coating portion with the resin composition. A thick film portion is likely to occur in the region. Therefore, even in such a case, the sliding property improving effect of the present invention can be effectively exhibited.

The sliding member (or bearing member) is not particularly limited, and may be, for example, a piston member, a cylinder member, a bearing member, or the like. The material of the sliding member is not particularly limited and may be either an organic material or an inorganic material.

Examples of the organic material include resin materials (for example, olefin resin such as polyethylene and polypropylene, styrene resin such as ABS resin, vinyl resin such as vinyl chloride resin, (meth)acrylic resin such as polymethylmethacrylate, Polyester terephthalate (PET) or other polyester resin, polycarbonate resin, polyamide resin, cellulose ester, cellulose derivative such as cellulose ether, thermoplastic elastomer, etc.; synthetic rubber material (isoprene rubber, butyl rubber, etc.); resin or rubber Foams (for example, foamed polyurethane, foamed polychloroprene rubber, etc.); materials derived from plants or animals (wood, pulp, natural rubber, leather, wool, etc.) and the like.

Examples of the inorganic material include ceramic materials (glass, silicon, cement, etc.); metallic materials [for example, simple metals (aluminum, iron, nickel, copper, zinc, chromium, titanium, etc.), alloys containing these metals (aluminum). Alloy, cast iron, steel (such as stainless steel), etc.] and the like.

Of these, a sliding member formed of an inorganic material, especially a sliding formed of a metal material (for example, at least one metal material selected from a simple substance of aluminum and an alloy containing aluminum, particularly an aluminum alloy) It is often a member.

In addition, although not necessarily required, the sliding member (for example, the sliding surface) may be surface-treated as necessary. The surface treatment is not particularly limited, and a conventional surface treatment can be used. Examples thereof include blast treatment (sandblast treatment, water blast treatment, etc.), etching treatment (plasma treatment, electrolytic etching, chemical etching, etc.), polishing treatment, and shot treatment. Treatment for adjusting the surface shape such as peening, chemical conversion treatment (or chemical treatment), anodic oxidation, ion implantation, surface heat treatment (induction hardening, flame hardening, etc.) for adjusting the surface composition, plating treatment [wet plating ( Electroplating, chemical plating) Dry plating or vapor deposition (PVD, CVD, etc.), hot-dip galvanizing (hot-dip galvanizing, hot-dip aluminum coating, etc.)], painting, lining treatment (resin lining, glass lining, etc.), thermal spraying treatment, etc. Examples include coating treatment. These surface treatments can be used alone or in combination of two or more.

Further, the maximum height roughness Rz of the sliding surface is not particularly limited and can be selected from the range of, for example, about 0.1 to 100 μm (for example, 1 to 50 μm), and from the viewpoint of easily improving the adhesiveness, for example, It may be 2 to 40 μm, preferably about 3 to 30 μm. In addition, in the present specification and claims, the maximum height roughness Rz can be measured in accordance with JIS B0601 (2001).

[Method of manufacturing automobile parts]
The automobile part of the present invention includes at least a resin coating step of coating the sliding surface of the sliding member with a resin to form a resin coating portion, and a processing step of cutting or grinding the resin coating portion to form a cutting surface. Contains.

(Resin coating process)
The method for forming the resin coating portion is not particularly limited, and for example, the resin coating portion may be formed by a conventional method (for example, coating) using the resin composition (in particular, curable composition). Typically, it can be formed by a curing step of applying the curable composition and curing the resulting coating film.

The coating method is not particularly limited, and a conventional method, for example, roll coating method, air knife coating method, blade coating method, rod coating method, reverse coating method, bar coating method, comma coating method, die coating method, gravure coating method, A screen coating method, a spray method, a spinner method and the like can be mentioned. Among these methods, a blade coating method, a bar coating method, a gravure coating method, a spray method and the like are widely used.

The coating film obtained by such a method may be heated and dried (preheated) before the curing treatment. The preheating temperature is, for example, 40 to 150° C., preferably 50 to 120° C., more preferably 60 to 100° C. (particularly 70 to 90° C.). The preheating time is 10 seconds or more (for example, 10 seconds to 10 minutes), preferably 20 seconds or more (for example, 20 seconds to 5 minutes), and more preferably 30 seconds or more (for example, 30 seconds to 2 minutes). May be.

In the curing step, depending on the type of curing agent and the like, curing may be performed by irradiating with active energy rays, heating may be performed, or these may be used in combination. Of these, usually, active energy rays are often irradiated.

Heat and/or light energy rays can be used as the active energy rays, and it is particularly useful to perform light irradiation using the light energy rays. As the light energy rays, radiation (gamma rays, X-rays, etc.), ultraviolet rays, visible rays, electron rays (EB), etc. can be used, and usually ultraviolet rays, electron rays, especially ultraviolet rays are often used. In particular, electron beam irradiation may be performed in applications where polymerization is possible without using a curing agent and high weather resistance is required.

Examples of the light source include deep UV lamp, low pressure mercury lamp, medium pressure mercury lamp, high pressure mercury lamp, ultra high pressure mercury lamp, halogen lamp, metal halide lamp, arc lamp, excimer lamp, laser light source (helium- A gas laser such as a cadmium laser or an excimer laser, a solid laser such as a YAG laser, a light source such as a semiconductor laser or a liquid laser such as a dye laser), a high frequency induced ultraviolet ray generator, or the like can be used. Irradiation light amount (irradiation energy or integrated quantity of light) varies depending on the thickness of the coating film, for example, 10 to 10000 mJ / cm ² (e.g., 50~7000mJ / ^cm 2), preferably 70~5000mJ / cm ^2, more preferably It may be about 100 to 2000 mJ/cm ² . Further, the substrate in order to improve the adhesion to (sliding member) may be increased the amount of light and irradiation time, the irradiation amount of light, for example, 300~10000mJ / cm ² (particularly 400~3000mJ / ^cm 2) It may be a degree.

In the case of an electron beam, a method of irradiating an electron beam with an exposure source such as an electron beam irradiation device can be used. The irradiation amount (dose) varies depending on the thickness of the coating film, but is, for example, about 1 to 200 kGy (gray), preferably 5 to 150 kGy, more preferably 10 to 100 kGy (particularly 20 to 80 kGy). The acceleration voltage is, for example, 10 to 1000 kV, preferably 50 to 500 kV, and more preferably 100 to 300 kV.

Irradiation with active energy rays (ultraviolet rays or electron rays) may be carried out in an inert gas (for example, nitrogen gas, argon gas, helium gas, etc.) atmosphere or in the absence of oxygen gas, if necessary.

Note that heat treatment (annealing treatment or aging treatment) may be performed after curing with active energy rays. In the aging treatment, the heating temperature is, for example, 30 to 250°C, preferably 50 to 220°C, more preferably 60 to 200°C (particularly 120 to 160°C). The heating time is, for example, 10 minutes to 10 hours, preferably 30 minutes to 5 hours, and more preferably about 1 to 3 hours. The aging treatment may be performed by gradually increasing the temperature.

On the other hand, when heat curing is performed using a thermal cationic polymerization initiator (or a thermal acid generator), the heating temperature is, for example, 30 to 200°C, preferably 50 to 190°C, more preferably about 60 to 180°C. is there. The heating time may be, for example, 10 minutes to 6 hours, preferably about 1 to 3 hours.

In the curing step, it is preferable to use active energy rays such as ultraviolet rays for curing because it can be used for a wide range of substrates.

(Processing process)
In the processing step, the cutting surface (or cutting portion) is formed by cutting and/or grinding (polishing) the thick film portion of the resin coating portion obtained in the resin coating step. The method of forming the cutting surface is not particularly limited as long as it can remove the thick film portion, and a conventional method can be used, for example, cutting is performed using a machine tool such as a grinder (or a grinder), a router, a milling machine, a machining center, or the like. Method, manual cutting with a cutting tool such as rasp or sandpaper, cutting with high energy rays such as laser light, radiation, heat rays, solid state such as sand blast, water jet, high pressure air, liquid state Alternatively, a method of colliding with a gaseous medium to perform cutting may be used. Since it is possible to sufficiently improve the slidability by a slight or simple method, polishing is often performed with abrasive paper such as sandpaper.

As described in the item of the resin coating portion, the thick film portion is usually formed on the edge portion in many cases, and therefore, at least a part of the resin coating portion in the vicinity of the edge portion is cut in the processing step. Thus, the slidability can be improved simply or efficiently, and the high smoothness of the smooth portion formed of the low-viscosity resin composition can be maintained. In the processing step, the vicinity of the edge portion may be cut while protecting the surface of the smooth portion with a masking tape or the like.

The processing region when cutting the vicinity of the edge portion may be appropriately selected according to the size and shape of the sliding member or the resin coating portion, and for example, a region 10 mm from the edge portion, preferably a region 8 mm from the edge portion. (For example, a region 5 mm from the edge portion), more preferably a region 3 mm from the edge portion (eg, a region 2 mm from the edge portion). In addition, a part of the area may be cut, or the entire area may be cut.

The removal of the thick film portion in the processing step can be confirmed by observing a cross section with a laser microscope or a laser displacement meter.

[Characteristics of automobile parts]
In the automobile part of the present invention, since the resin coating portion has the cutting surface, it is possible to suppress an increase in the contact resistance with the sliding partner material and improve the slidability. Further, when a primer layer or a predetermined curable composition (for example, the curable composition (B) having the resin coating portion shown in FIG. 1 or the like) is used, the resin coating can be formed with high adhesion. Therefore, even if an excessive load is applied to the resin coating portion by cutting, peeling can be effectively suppressed. Further, it is possible to form a resin coating portion having not only good appearance and high surface smoothness but also high hardness and abrasion resistance and excellent slidability.

As the adhesiveness of the resin coating portion in the automobile part, the mass that has not been peeled off in the tape peeling test described in Examples described later may be selected from the range of 20 masses or more, for example, 30 masses or more (for example, , 50 to 100 squares), preferably 70 squares or more, more preferably 90 squares or more, and particularly 100 squares.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. The materials and evaluation methods used in the examples are shown below.

[material]
(Substrate or sliding member)
Aluminum alloy ADC12: #600 polished finish, plate shape of size 60 mm×60 mm×2 mm, arithmetic average roughness Ra=0.4566 μm, maximum height roughness Rz=4.012 μm, custom-made automobile manufactured by Nippon Test Panel Co., Ltd. Pistons: Pistons for gasoline engine cars made of cast aluminum with ridges on the skirt (polymerizable compound)
Alicyclic epoxy compound: 3,4,3',4'-diepoxybicyclohexyl 1,4-BDGE: 1,4-butanediol diglycidyl ether OXT-101: 3-ethyl-3-hydroxymethyloxetane, Toago Synthetic Co., Ltd. "Aron oxetane OXT-101"
HBVE: 4-hydroxybutyl vinyl ether (polymerization initiator)
CPI-100P: Propylene carbonate solution of triarylsulfonium hexafluorophosphate, "CPI-100P" manufactured by San-Apro Ltd.
(Leveling agent)
BYK-SILCLEAN 3720: Solution of polyether-modified polydimethylsiloxane having a hydroxyl group [solvent: methoxypropanol, nonvolatile content (10 minutes, 150°C): 25% by weight, hydroxyl value (active ingredient): 29 mgKOH/g]], Big Chemie Made in Japan "BYK-SILCLEAN 3720"
BYK-325: Polyester-modified polymethylalkylsiloxane solution [solvent: γ-butyrolactone/alkylbenzene (weight ratio: 1/1), more specifically, solvent composition: γ-butyrolactone/alkylbenzene solvent naphtha/1,2,4 -Trimethylbenzene/xylene (weight ratio: (20-30)/(10-20)/6.84/(0.1-1)), solvent content: 48% by weight, non-volatile content (60 minutes, 105°C) : 52% by weight], "BYK-325" manufactured by Big Chemie Japan Co., Ltd.

[Evaluation methods]
(viscosity)
The viscosity of the curable composition at 25° C. was measured using an E-type viscometer “TVE-25H” manufactured by Toki Sangyo Co., Ltd.

(Shape observation)
The surface shape of the coating film edge portion was measured using a fine shape measuring machine (“ET4000A” manufactured by Kosaka Laboratory Ltd.).

(Film thickness evaluation)
The thickness of the coating film was measured using a dual type film thickness meter (“LZ-990” manufactured by Kett Scientific Research Co., Ltd.).

(Tape peel test)
Make 100 squares of 2 mm x 2 mm square on the coated surface, 10 squares x 10 squares, attach cellophane tape to the surface, and peel off the tape abruptly, then apply it to 80% or more of the total area. The adhesion was evaluated simply by counting the number of masses in which the film remained.

(Appearance evaluation)
The appearance of the coated surface was evaluated according to the following criteria.

◯: The resin coating part (cured product) has no unevenness, and there is no evidence that the coating agent (curable composition) has been repelled. ×: The resin coating part has unevenness or there is a trace that the coating agent has been repelled.

(Evaluation of smoothness)
According to JIS B0601 (2001), the arithmetic mean roughness Ra [μm] of the coating film (cured product) was measured using a fine shape measuring machine (“ET4000A” manufactured by Kosaka Laboratory Ltd.).

(Abrasion test)
After performing an abrasion test under the following conditions, the presence or absence of sliding marks and the maximum value of the depth of sliding marks were observed using a fine shape measuring machine (“ET4000A” manufactured by Kosaka Laboratory Ltd.).

Abrasion test conditions Load: 2.5 [N] and 5 [N]
Environment: Toyota Castle Oil 0W-30 immersion Temperature: 80℃
Counterpart material: SUJ2 hard ball (φ10mm)
Round-trip speed: 1.8 Hz
Reciprocating width: 10 mm
Time: 5 minutes.

[Example 1]
60 parts by mass of alicyclic epoxy compound, 20 parts by mass of 1,4-BDGE, 10 parts by mass of OXT-101, 10 parts by mass of HBVE, 0.5 parts by mass of BYK-325 and 2 parts by mass of CPI-100P are mixed and cured. A sex composition was prepared. The viscosity of the curable composition at 25° C. was 19 mPa·s. A flat plate member made of aluminum alloy ADC12 as a base material is degreased with acetone, and the curable composition is applied to one surface of the base material using a wire bar #10 without applying a primer on the base material. After coating on the entire surface, prebaking was performed at 80° C. for 1 minute. By using a belt conveyer type high-pressure mercury lamp (Ushio Co., Ltd. "UVC-02516S1"), 120 W lamp output, ultraviolet rays were irradiated at a conveyor speed of 5.5 m / min, UV in the processing of integrated light intensity 1600 mJ / cm ² did. Finally, the coating film of the curable composition was cured by heat treatment (aging treatment) at 80° C. for 1 hour and then at 150° C. for 1 hour to prepare a molded product having a resin coating portion. FIG. 6 shows the film thickness data of the resin coating portion near the end portion of the obtained molded body.

As is clear from the results of FIG. 6, a thick film portion having a large film thickness is formed at the edge portion (or the end portion of the molded body) of the resin coating portion. A 6 mm region from each end of this molded body was ground with #400 sandpaper to remove the thick film portion. FIG. 7 shows the film thickness data of the molded body from which the thick film portion has been removed.

As is clear from FIG. 7, the resin-coated portion of the obtained molded body had the same form as the example described in FIG. 3, and the angle θ (tilt angle θ) was about 1.5° at the maximum. The average film thickness in the smooth portion was 28 μm, the arithmetic average roughness Ra ₁ of the surface of the smooth portion was 0.028 μm, and the arithmetic average roughness Ra ₂ of the cut surface was 0.353 μm. The area ratio of the resin coating portion after cutting to the entire sliding surface was 80%, and the area ratio of the smooth portion surface to the cutting surface was 80/20. Further, the result of the tape peeling test was 100/100, the result of the appearance evaluation was ◯, and the result of the abrasion test was no damage at loads of 2.5N and 5N.

[Example 2]
A curable composition for forming a top coat layer was prepared by mixing 100 parts by mass of an alicyclic epoxy compound, 1 part by mass of BYK-SILCLEAN 3720 and 2 parts by mass of CPI-100P. The viscosity of the curable composition at 25° C. was 47 mPa·s. In addition, as a composition for forming a primer layer, a dry coat 3000 manufactured by Sumiko Lubricant Co., Ltd. was used. The viscosity of the composition for forming a primer layer at 25° C. was 290 mPa·s. Spray dry coat 3500 as a primer layer (first layer) on the skirt of an automobile piston as a base material degreased with acetone using a hand spray gun ("W-101" manufactured by Anest Iwata Co., Ltd.) After coating, it was baked at 200° C. for 120 minutes. The average film thickness of the coating film of the primer layer was 9 μm.

On the obtained primer layer, the prepared curable composition for forming a topcoat layer was used as a topcoat layer (second layer) using a hand spray gun (“W-101” manufactured by Anest Iwata Co., Ltd.). After spray coating, prebaking was performed at 80° C. for 1 minute, followed by irradiation with ultraviolet rays at a conveyor speed of 1.0 m/min using a conveyor type ultraviolet curing device (“Aicure” manufactured by Panasonic Corporation), and a metal halide lamp ( It was treated with ultraviolet light having an output of 70%, an illuminance of 50 mW/cm ² ) and an integrated light amount of 1600 mJ/cm ² . Finally, the coating film of the top coat layer was cured by heat treatment (high temperature baking treatment) at 150° C. for 1 hour to prepare a molded body (paint piston) having a primer layer and a top coat layer. The average film thickness of the smooth portion of the top coat layer was 18 μm.

Since a thick film portion is formed at the edge portion of the resin coating portion of the obtained molded body, as shown in FIG. 8, an area of about 2 mm from each end portion of this molded body is sanded with #400 sandpaper. By cutting, a molded body from which the thick film portion was removed was obtained.

The molded body from which the thick film portion was removed had the same form as the example described in FIG. The area ratio of the resin coating portion to the entire sliding surface was about 95%, and the area ratio of the smooth portion surface to the cutting surface was 90/10. Moreover, the result of the tape peeling test was 100/100, and the result of the appearance evaluation was ◯.

[Example 3]
Alicyclic epoxy compound 40 parts by mass, 1,4-BDGE 20 parts by mass, OXT-101 30 parts by mass, HBVE 10 parts by mass, BYK-325 0.5 parts by mass and CPI-100P 2 parts by mass are mixed and cured. A sex composition was prepared. The viscosity of the curable composition at 25° C. was 16 mPa·s. The curable composition is sprayed using a hand spray gun (“W-101” manufactured by Anest Iwata Co., Ltd.) without applying a primer on the skirt portion of a vehicle piston degreased with acetone as a base material. After coating, pre-bake at 80° C. for 1 minute, and then, using a conveyor type ultraviolet curing device (“Aicure” manufactured by Panasonic Corporation), irradiate ultraviolet rays at a conveyor speed of 1.0 m/min to output a metal halide lamp (output). 70%, an illuminance of 50 mW/cm ² ) and an integrated light amount of 1600 mJ/cm ² were used for the treatment. Finally, heat treatment (high temperature baking treatment) was performed at 150° C. for 1 hour to prepare a molded body having a resin coating portion.

In the resin coating part of the obtained molded body, the average film thickness of the smooth part was 16 μm, and the maximum film thickness of the thick film part formed at the edge part was 57 μm. Therefore, as shown in FIG. 8, a region of about 2 mm from each end of this molded body was ground with #400 sandpaper to obtain a molded body from which the thick film portion was removed.

The molded body from which the thick film portion was removed had the same form as the example described in FIG. The area ratio of the resin coating part to the entire sliding surface was about 95%, and the area ratio of the smooth part surface to the cutting surface was 95/5. Moreover, the result of the tape peeling test was 100/100, and the result of the appearance evaluation was ◯.

The automobile part of the present invention is excellent in slidability (smoothness, wear resistance, etc.), and thus can be effectively used as a sliding member (or bearing member) of an automobile, for example, a cylinder, a piston, a bearing, or the like. .

1, 11, 21, 31... Automotive parts 2... Sliding member 3... Sliding surface 4, 14, 24, 34... Resin coating part 5... Thick film part (or abnormal film thickness part)
16, 26, 36... Smooth part 17, 27, 37... Cutting part and/or grinding part 17a, 27a, 37a... Cutting surface and/or grinding surface 18, 38... Non-contact part (non-sliding part or non-coating part) )
38a... Projection (or projection)
40... Edge part of resin coating part (or base material)

Claims (12)

An automobile part including a sliding member having a sliding surface and a resin coating portion formed on at least a part of the sliding surface, wherein the resin coating portion has a cutting surface and/or a grinding surface. . The resin coating portion has a smooth portion having a uniform thickness and a cutting portion and/or a grinding portion including a cutting surface and/or a grinding surface formed continuously with the smooth portion, and the cutting portion and/or the grinding portion. The automobile part according to claim 1, wherein the maximum film thickness of the part is equal to or less than the maximum film thickness of the smooth part. The automobile part according to claim 2, wherein the cutting portion and/or the grinding portion is formed on at least a part of a peripheral portion of the resin coating portion. The automobile part according to claim 3, wherein the film thickness of the cutting portion and/or the grinding portion is formed so as to become smaller as it goes away from the smooth portion. The arithmetic average roughness Ra ₁ of the surface of the smooth portion measured according to JIS B0601 (2001) is 0.2 μm or less, and the arithmetic average roughness Ra _{2 of the} cutting surface and/or the grinding surface is Ra ₁ or more. The automobile part according to any one of claims 2 to 4. The automobile part according to any one of claims 1 to 5, wherein the sliding surface is at least curved. The automobile part according to any one of claims 1 to 6, wherein the resin coating portion covers the sliding member at an area ratio of 80% or more with respect to the entire sliding surface. The automobile part according to any one of claims 1 to 7, wherein the sliding member is made of a metal material. The resin coating part is formed of at least a cured product of a curable composition containing a curable resin, and the viscosity of the curable composition at 25° C. is 200 mPa·s or less. Auto parts. The automobile part according to any one of claims 1 to 9, which is a piston. On the surface orthogonal to the direction in which the piston slides in the cylinder, the resin coating portion formed on the skirt portion as a sliding surface has a smooth portion extending along the path of a perfect circle or ellipse on the surface of this resin coating portion. And a cutting surface and/or a grinding surface extending from the end portion of the smooth portion toward the skirt portion at an angle greater than 0° with respect to the tangent line of the track at the end portion. Described automobile parts. A method comprising: a resin coating step of coating a resin on a sliding surface of a sliding member to form a resin coating portion; and a processing step of cutting or grinding the resin coating portion to form a cutting surface and/or a ground surface. The method for manufacturing an automobile part according to any one of 1 to 11.