WO2015119273A1

WO2015119273A1 - Vehicle wheel and method for producing same

Info

Publication number: WO2015119273A1
Application number: PCT/JP2015/053522
Authority: WO
Inventors: 篠田　誠; 利夫永田; 雅孝内田
Original assignee: 日立金属株式会社
Priority date: 2014-02-07
Filing date: 2015-02-09
Publication date: 2015-08-13
Also published as: JPWO2015119273A1; JP6455446B2

Abstract

The objective of the present invention is to provide: a vehicle wheel having superior corrosion resistance and able to form a coating film having a uniform thickness at an edge at the rear of a window section; and a method for producing the vehicle wheel. The method for producing a vehicle wheel, which is provided with at least a rim section, a hub section, a spoke section, and a window section, includes at least a rounding step containing: a chamfering step for forming a chamfered surface by chamfering the edge between the side surface of the spoke section and the rear surface of the spoke section and positioned at the boundary between the window section and the rear surface; a first rounding step for forming a first curved surface by rounding a first edge that is the edge between the side surface of the spoke section and the chamfered surface; and a second rounding step for forming a second curved surface by rounding a second edge that is the edge between the rear surface of the spoke section and the chamfered surface. The radius (R1) of curvature of the first curved surface is greater than the radius (R2) of curvature of the second curved surface.

Description

Vehicle wheel and method of manufacturing the same

The present invention relates to a vehicle wheel for a four-wheeled vehicle and a manufacturing method thereof.

In a light alloy wheel manufactured by casting, which is an automobile (for example, passenger car) part, a multi-layer coating is applied to the surface of the wheel base in order to exhibit a high-quality appearance. For example, in general, a primer layer made of powdered polyester, acrylic, epoxy, urethane, or epoxy polyester-based resin coated with a thickness of about 50 to 100 μm in order to hide the unevenness of the casting surface, the color of the appearance There are three-layer coatings comprising a color base layer mainly composed of polyester or acrylic resin for releasing, and a clear layer for improving the weather resistance, corrosion resistance, and the like while giving the color of the color base layer. In addition, in order to further enhance the high quality, there are some that have a metallic silver coating (plating coating) reminiscent of a polished surface of metal.

FIG. 9 is a plan view of a vehicle wheel (hereinafter sometimes simply referred to as a wheel) viewed from the front side of the disk surface. A wheel 1 has an annular rim portion 2 on which a tire (not shown) is mounted, a hub portion 5 having a hub hole 3 at the center for connecting the wheel to the axle and a bolt hole 4 for connecting a bolt for fixing the wheel to the axle. The spoke portion 6 that extends radially from the hub portion 5 toward the rim portion 2 and connects the hub portion 5 and the rim portion 2 is a main component. A space surrounded by the rim part 2, the hub part 5, and the spoke part 6 is a window part 7. The front side of the disk portion 8 including the window portion 7, the spoke portion 6, and the hub portion 5 has a particularly great influence on the design as a design surface of the wheel 1.

¡When painting a vehicle wheel, it is necessary to consider anti-rust measures for the edges formed by processing the wheel base. In particular, the spoke portion has a back surface on the back side of the disk portion and a side surface that forms the outline of the window portion, and when the back side of the disk portion is processed by lathe processing, the back surface and the side surface are also processed. For example, in this case, the end portion of the back surface and the side surface of the spoke portion, which is located at the boundary between the back surface of the spoke portion and the window portion, may have an edge shape having an acute angle or an angle close to an acute angle. . The primer is baked at a temperature of about 100 to 200 ° C. after powder coating and a coating film is formed on the wheel. During this baking, the primer resin becomes liquid, and the primer may shrink toward the center of the painted surface due to surface tension or stress. In this case, at the edge part of the edge shape, the primer is pulled on both sides of the ridge line, so that it may be difficult to form a coating film having a sufficient thickness on the surface of the edge part. If the coating film of the primer does not have a sufficient thickness at the edge of the edge shape, the corrosion resistance is insufficient at the edge, and yarn rust is likely to occur. When yarn rust occurs, not only does the rust spread around the end portion and the appearance is deteriorated, but in the case of remarkable, performance such as durability of the wheel may be lowered.

In order to prevent the occurrence of yarn rust at the edge of the edge shape, for example, Patent Document 1 discloses a method for manufacturing a vehicle wheel that executes the following steps (a) to (f). (A) a step of integrally casting a disc portion having a plurality of decorative holes and a rim portion spaced apart in the circumferential direction; and (b) making a hub hole and a bolt hole in the disc portion, A machining step for cutting the back surface, (c) a chamfering step for chamfering an edge between the inner peripheral surface of the decorative hole made of a casting surface and the back surface of the disk portion made of a cutting surface, and (d) barrel polishing. And (e) applying an annular brush disposed so as to occupy at least the entire region of the decorative hole forming region to the annular decorative hole forming region where the plurality of decorative holes are disposed on the back surface of the disk portion. A brush polishing step for polishing the edge of the border between the inner peripheral surface of the decorative hole and the back surface of the disc portion by rotating the annular brush around the central axis of the disc portion; and (f) a coating step; Run It is a manufacturing method of the vehicle wheel. Since the edge of the vehicle wheel obtained by this manufacturing method is well processed by brush polishing and rounded, the coating film adheres well and the aluminum ingot is not exposed, so it is possible to prevent rust generation due to long-term use Yes.

Japanese Patent No. 4516509

However, as a result of investigations by the inventors, it has been found that the coating film may not be satisfactorily adhered to the edge of the edge shape even by the vehicle wheel manufacturing method described in Patent Document 1. The reason will be described with reference to FIGS.

FIG. 10 is a cross-sectional view taken along the line AA in which the spoke portion 6 of the wheel 1 shown in FIG. 9 is cut at right angles to the radial direction of the wheel. In FIG. 10, the upper side is the front side of the disk surface, and the lower side is the back side of the disk surface. Here, in the processing step of Patent Document 1, the outer side surface 41 of the spoke part and the spoke rear surface 42 on the disk surface back side are cut. After the cutting process, an end B (hereinafter sometimes simply referred to as an end) between the spoke back surface 42 and the outer side surface 41 (the inner peripheral surface of the window) of the spoke facing the window is formed. When the wheel is formed by a casting method, the outer side surface 41 of the spoke portion may have a draft γ to facilitate removal of the cast wheel base from the mold. By having this draft gradient γ, the end B tends to have an acute angle. In addition, in order to reduce the weight of the spoke portion, there may be a structure in which the inside is cast as shown in FIG.

When this wheel is painted, a coating with a sufficient thickness is not formed on the end B. Therefore, after the processing step, the end B is chamfered (chamfering step) before the coating step. In the chamfering process, the tip of the end B is removed by a grinder or the like. FIG. 11 is a diagram showing a chamfering method for chamfering an end portion B between a spoke back surface 42 and an outer side surface 41 of a spoke portion facing a window portion in a conventional vehicle wheel manufacturing method. As shown in FIG. 11, the end portion B may be referred to as an end portion 43 (hereinafter referred to as a first end portion) formed by a chamfered surface 40 formed by chamfering and a side surface 41 outside the spoke portion. .) And the chamfered surface 40 and the back surface 42 of the spoke portion, two end portions 44 (hereinafter sometimes referred to as second end portions) are newly formed.

FIG. 12 is a diagram showing a rounding method for rounding the end B after the chamfering. The processing means is a brush polishing method. A brush 9 made of an aggregate of a large number of fibers carrying abrasive grains is disposed on the back side of the disk surface, and the free end 10 of the brush 9 is placed in the window 7 to move the brush in a direction along the back surface of the spoke. Accordingly, the brush 9 polishes and rounds the first end portion 43 and the second end portion 44. In this case, the second end portion 44 is more polished.

FIG. 13 is a cross-sectional view of the end B after rounding. When the end portion B is rounded by the brush polishing method described in FIG. 12, the edge portion B has an arc shape shown in FIG. As a result of more polishing of the second end portion, the radius of curvature R2 of the second arc surface 46 with the second end portion 44 rounded is equal to the radius of curvature R1 of the first arc surface 45 with the first end portion 43 rounded. Bigger than.

FIG. 14 is a cross-sectional view of the end B painted after rounding. A coating film having a sufficient thickness can be formed on the second arc surface 46 having a large curvature radius, but the coating film on the first arc surface 45 having a small curvature radius is thin. On the first circular arc surface, the corrosion resistance becomes insufficient and yarn rust is likely to occur. When the yarn rust is generated and spreads around, the appearance is deteriorated, and if it is remarkable, the durability may be lowered. is there. By coating the primer many times, the coating can be thickened, but this is not preferable because it increases the number of production steps. The radius of curvature R2 of the second arc surface after rounding increases, and the radius of curvature R1 of the first arc surface decreases, the first end being two ends formed in the chamfering process of the end B And the respective angles (inner angles) of the second end portion may be substantially the same.

Therefore, the present invention can form a coating film with a uniform thickness on the edge between the back surface of the spoke part and the side surface of the spoke part, located at the boundary between the back surface and the window part, and has excellent corrosion resistance. Another object is to provide a vehicle wheel and a method of manufacturing the same.

A vehicle wheel manufacturing method according to a first aspect of the present invention for solving the above-described problems includes an annular rim portion for mounting a tire, a hub portion having a hub hole for connecting the vehicle wheel to an axle, and the hub. The vehicle includes at least a spoke portion that extends radially from a portion toward the rim portion and connects the hub portion and the rim portion, and a window portion that is a space surrounded by the rim portion, the hub portion, and the spoke portion. A chamfering method for forming a chamfer by chamfering an end portion of the back surface and the side surface of the spoke portion, which is located at a boundary between the back surface of the spoke portion and the window portion, in the wheel manufacturing method; A first rounding step of rounding a first end that is an end of a surface and a side of the spoke portion to form a first arc surface; and a second rounding end of the chamfered surface and the back of the spoke portion End At least a rounding step including a second rounding step for forming a second arcuate surface, wherein the radius of curvature R1 of the first arcuate surface is larger than the radius of curvature R2 of the second arcuate surface. Method.

In the first invention of the present application, the chamfering step can process the inner angle α of the first end portion to be larger than the inner angle β of the second end portion. Before the rounding step, in the chamfering step, the inner radius α of the first end portion is chamfered so as to be larger than the inner angle β of the second end portion. It becomes easy to make it larger than the radius R2.

In the first invention of the present application, the rounding step includes a brush arranging step of arranging a brush on the back surface side of the disk portion including the hub portion, the spoke portion, and the window portion, and the brush and the back surface of the disk portion. At least a rubbing step of sliding the first end and the second end with the brush to form the first arc surface and the second arc surface, the rubbing step Thus, the radius of curvature R1 of the first arc surface can be made larger than the radius of curvature R2 of the second arc surface. By rubbing with a brush, it becomes easy to make the curvature radius R1 larger than the curvature radius R2.

In the first invention of the present application, the brush is a roll-type brush having a rotating shaft, and the rubbing step rotates in such a manner that the rotating shaft of the roll-type brush rotates in parallel with the back surface of the disk portion. It can be set as the process of rotating relatively concentrically with respect to the back surface of a part, and rubbing. By using a roll type brush, it becomes easy to make the curvature radius R1 larger than the curvature radius R2.

A vehicle wheel according to a second invention of the present application for solving the above-described problems is provided with an annular rim portion for mounting a tire, a hub portion having a hub hole for connecting the vehicle wheel to an axle, and the hub portion. A vehicle wheel comprising at least a spoke portion that extends radially toward the rim portion and connects the hub portion and the rim portion, and a window portion that is a space surrounded by the rim portion, the hub portion, and the spoke portion. An end of the back surface and the side surface of the spoke portion located at the boundary between the back surface of the spoke portion and the window portion is a first arc surface that is an arc surface in contact with the side surface of the spoke portion, and the spoke The vehicle wheel includes a second arc surface that is an arc surface in contact with the back surface of the portion, and a radius of curvature R1 of the first arc surface is larger than a radius of curvature R2 of the second arc surface.

In the second invention of the present application, the radius of curvature R2 of the second arcuate surface can be 200 μm or more and 600 μm or less. When the curvature radius R2 is within this range, a coating film having a sufficient film thickness can be applied to the second arc surface, and thus the corrosion resistance is excellent. When the curvature radius R2 is smaller than 200 μm, it is not possible to obtain a sufficient dry coating film to prevent rust even if the second arc surface is coated, and the corrosion resistance is inferior. On the other hand, if the radius of curvature R2 is larger than 600 μm, a longer processing time is required for the rounding process, which causes inconveniences such as reduced productivity and faster brush consumption.

In the vehicle wheel manufacturing method according to the first aspect of the present invention, a coating film having a uniform thickness is formed at the end of the back surface and the side surface of the spoke portion located at the boundary between the back surface of the spoke portion and the window portion. be able to.
The vehicle wheel according to the second invention of the present application can provide a vehicle wheel having excellent corrosion resistance.

The flowchart which shows the manufacturing process of the wheel for vehicles by a casting method. Sectional drawing of the edge part B after a chamfering process. The figure which shows the state of the moment when a brush hits the 1st edge part. The figure which shows the state which the brush advanced a little from the state shown in FIG. The figure which shows the state which the brush further advanced from the state shown in FIG. Sectional drawing of the edge part B after a rounding process. Sectional drawing of the edge part B of the painted wheel after implementing the manufacturing method of the vehicle wheel which concerns on this invention. Schematic diagram of local rust. It is the top view which looked at the vehicle wheel from the front side of the disk surface. FIG. 9 is a cross-sectional view taken along the line AA in which the spoke portion 6 of the wheel 1 shown in FIG. 8 is cut at right angles to the radial direction of the wheel. It is a figure which shows the chamfering processing method which chamfers the edge part B of the spoke back surface 42 and the outer side surface 41 of the spoke part which faces a window part in the manufacturing method of the conventional vehicle wheel. It is a figure which shows the rounding method which rounds the edge part B after a chamfering process. It is sectional drawing of the edge part B after a rounding process. It is sectional drawing of the edge part B painted after rounding. It is sectional drawing of the edge part B after coating.

The present invention will be described based on specific embodiments with reference to the drawings. In addition, this invention is not limited to the Example demonstrated below, In addition, as long as there exists an effect of this invention, it can deform | transform suitably within the range of identity.

According to a first aspect of the present invention, there is provided a vehicle wheel manufacturing method comprising: an annular rim portion for mounting a tire; a hub portion having a hub hole for connecting the vehicle wheel to an axle; and the hub portion toward the rim portion. A spoke portion that extends radially and connects the hub portion and the rim portion, and a vehicle wheel manufacturing method including at least a window portion that is a space surrounded by the rim portion, the hub portion, and the spoke portion. A chamfering step of chamfering an end of the back surface and the side surface of the spoke portion located at the boundary between the back surface of the spoke portion and the window portion to form a chamfered surface; and the chamfered surface and the side surface of the spoke portion. A first rounding step of rounding the first end that is the end of the first round to form a first arc surface, and rounding the second end that is the end of the chamfered surface and the back surface of the spoke portion. Form a circular arc surface Wherein at least the step rounding comprises a second rounding step, the first arcuate surface the radius of curvature R1 of the following effects by adopting a configuration in larger, than the radius of curvature R2 of the second arc surface.

That is, when rounding is performed on the end of the back surface and the side surface of the spoke portion located at the boundary between the back surface of the spoke portion and the window portion by a conventional brush polishing method, the end of the chamfered surface and the side surface of the spoke portion is Since the second end portion, which is the end portion between the chamfered surface and the back surface of the spoke portion, is polished more than the first end portion that is the portion, the second end portion has a thickness with sufficient corrosion resistance. When the first end portion is rounded to a circular arc surface that is rounded to the extent that a coating film can be formed, the amount of polishing is small. However, by setting the inner angle α of the first end portion to be larger than the inner angle β of the second end portion, the radius of curvature R1 of the first arc surface is set to the second even if the amount of polishing when the second end portion is rounded is small. It can be larger than the radius of curvature R2 of the arc surface. As a result, the vehicle wheel manufacturing method according to the first aspect of the present invention provides a coating film having a uniform thickness at the end of the back surface and the side surface of the spoke portion located at the boundary between the back surface of the spoke portion and the window portion. Can be formed.

A vehicle wheel according to a second invention of the present application includes an annular rim portion for mounting a tire, a hub portion having a hub hole for connecting the vehicle wheel to an axle, and a radial direction from the hub portion toward the rim portion. A vehicle wheel comprising at least a spoke portion that extends and connects the hub portion and the rim portion, and a window portion that is a space surrounded by the rim portion, the hub portion, and the spoke portion, the back surface of the spoke portion The end of the back surface and the side surface of the spoke portion located at the boundary between the first and second window portions is a first arc surface that is an arc surface in contact with the side surface of the spoke portion, and an arc surface in contact with the rear surface of the spoke portion. By adopting a configuration in which the second arc surface is provided and the radius of curvature R1 of the first arc surface is larger than the radius of curvature R2 of the second arc surface, the following effects can be obtained.

That is, the vehicle wheel according to the second invention of the present application forms a coating film having a uniform thickness at the end of the back surface and the side surface of the spoke portion, which is located at the boundary between the back surface of the spoke portion and the window portion. Therefore, it is possible to provide a vehicle wheel having excellent corrosion resistance in which yarn rust hardly occurs at the end portion.

FIG. 1 illustrates, as an example, a process for manufacturing a vehicle wheel by a casting method. The present invention is not limited to this manufacturing process. The vehicle wheel is manufactured through a substrate forming step 101, a heat treatment step 102, a processing step 103, a chamfering step 104, a rounding step 105, a pre-painting treatment step 106, and a painting step 107.

In the base body forming step 101, a molten metal is poured into a mold, and after cooling, is taken out of the mold to obtain a vehicle wheel base body including at least a rim portion, a hub portion, a spoke portion, and a window portion. For example, when a vehicle wheel made of an aluminum alloy is manufactured by a casting method, a molten aluminum alloy whose components are adjusted so as to conform to a standard such as AC4CH in a base forming process is formed in a mold by a low pressure casting method or a gravity casting method. The vehicle body of the vehicle wheel is obtained by pouring into the mold and removing it from the mold after cooling. As shown in FIG. 9, the base body includes a rim portion 2, a hub portion 5, and a spoke portion 6 as main components, and a window portion 7 that is a space surrounded by the rim portion 2, the hub portion 5, and the spoke portion 6 on the design surface. Is provided. As shown in FIG. 10, the side surface 41 on the outer side of the spoke portion of the base of the vehicle wheel has an inclination from the front side to the back side of the disk surface, and the inclination angle is more than 0 ° and less than 90 °. This inclination is also called a draft gradient γ, and this gradient is given for the purpose of easily removing the substrate from the mold in the casting method. When this inclination angle is 0 ° or less, the design of the wheel is impaired, and when it is 90 ° or more, the spoke portion 6 cannot be formed. The substrate forming step includes the back surface processing when the back surface processing of the spoke portion of the substrate is performed. As shown in FIG. 2, the angle θ of the edge B between the spoke back surface 42 and the outer side surface 41 (inner peripheral surface of the window portion) of the spoke portion facing the window portion is determined from design and ease of manufacture. It can be greater than 0 ° and less than 90 °.

Next, in order to adjust the structure of the aluminum alloy constituting the substrate and obtain the desired mechanical characteristics, a heat treatment step 102 for heat-treating the substrate is performed as necessary. Next, it is necessary to have a processing step 103 for chamfering or deburring other than the end of the back surface and the side surface of the spoke portion located at the boundary between the back surface of the spoke portion and the window portion. Do it accordingly. The chamfering step 104 and the rounding step 105 are as described above, but details will be described later. Next, as a pre-coating process on the substrate, a pre-coating process 106 for performing degreasing, chemical conversion or the like on the surface of the substrate is performed as necessary.

Finally, the vehicle body is painted in the painting process 107 to complete the vehicle wheel. In the painting process, for example, a primer paint is sprayed on the front and back sides of the disk portion and the side surfaces of the spoke portions to form a primer layer, and a color base paint is sprayed on the primer layer, and the color base paint is baked to form a color base layer. And a coating method in which a clear paint is sprayed on the color base layer and then the clear paint is baked. As the primer paint, resins such as polyester, acrylic, epoxy, and urethane can be used. The dry thickness of the primer layer is preferably about 40 μm to 200 μm when it is necessary to hide the unevenness of the cast surface of the wheel. An electrostatic coating apparatus can be used as the coating apparatus. As the color base paint, for example, an acrylic, polyester, epoxy resin paint or the like can be used. Examples of the coating on the wheel include a method of spraying with air spray or electrostatic coating. The dry thickness of the color base layer is preferably 10 μm to 40 μm. As the clear paint, an acrylic solvent paint excellent in transparency, gloss, weather resistance and the like can be used. The dry film thickness of the clear layer can be 10 μm to 40 μm. FIG. 7 is a cross-sectional view of the end B of the wheel after the clear coating is carried out in the vehicle wheel manufacturing method according to the present invention. According to the vehicle wheel manufacturing method of the present invention, a coating film having a substantially uniform thickness can be formed.

The chamfering step and the rounding step in the vehicle wheel manufacturing method according to the present invention will be described with reference to FIGS.

[Chamfering process]
FIG. 2 shows a cross section of the end B after the chamfering process. The inner angle of the first end portion 43 that is the end portion between the chamfered surface 40 and the outer side surface 41 of the spoke portion is α (°), and the second end is the end portion between the chamfered surface 40 and the back surface 42 of the spoke portion. When the internal angle of the portion 44 is β (°), chamfering is preferably performed so that α> β. The chamfering means is not particularly limited. For example, chamfering can be performed by holding and rotating the grindstone so that the internal angles α and β satisfy α> β, and moving the grindstone along the contour of the tip while pressing the grindstone against the tip of the end B. it can.

[Rounding process]
3 to 5 show examples of the processing means for the end B in the rounding step. The rounding step includes at least a first rounding step of applying the brush 9 from the back surface 42 side of the spoke portion and rounding the first end portion 43 formed in the chamfering step, and a second rounding step of rounding the second end portion 44. . The length of the brush 9 is preferably longer than the distance in the central axis direction of the disk portion between the hub portion 5 which is a mounting surface for attaching the wheel to the vehicle and the spoke back surface 42. Specifically, the brush length is preferably about 50 mm to 200 mm, and the brush pressing pressure is preferably about 0.05 to 1.0 MPa. FIG. 3 shows a state at the moment when the brush 9 hits the first end portion 43. A location close to the tip of the brush 9 hits the first end portion 43, and a location below the brush 9 hits the second end portion 44. The brush 9 rounds each end by proceeding in the direction of the arrow in the figure. FIG. 4 shows a state where the brush is slightly advanced from the state shown in FIG. The brush 9 is separated from the first end portion 43, and the brush 9 continues to hit the second end portion 44. FIG. 5 shows a state where the brush has further advanced from the state shown in FIG. The brush 9 remains away from the first end 43 and the brush 9 continues to hit the second end 44. Since the time for which the brush 9 is in contact with the first end 43 is longer than the time for which the brush 9 is in contact with the first end 43, the polishing of the second end 44 proceeds faster than the polishing of the first end 43. . When the polishing of the second end 44 progresses to a predetermined radius of curvature (R2), the polishing amount of the first end 43 is less than the polishing amount of the second end. However, the internal angle α (°) of the first end portion 43 is larger than the internal angle β (°) of the second end portion 44. Therefore, as shown in the cross section of the end portion B after the rounding step in FIG. 6, the radius of curvature (R2) of the second end portion 44 is increased until a thick coating film can be formed, and the second arc surface Even if 46 is formed, the 1st circular arc surface 45 which makes the curvature radius (R1) of the 1st end part 43 a larger value can be formed. In addition, a 1st rounding process and a 2nd rounding process can perform these processes simultaneously, or can be performed separately. Moreover, a 1st rounding process can be performed previously and a 2nd rounding process can also be performed previously. The processing time for the rounding process is typically 5 to 30 seconds.

Hereinafter, the present invention will be described more specifically based on examples and conventional examples, but the present invention is not limited to the following examples.

Example 1
[Substrate forming step]
The molten Al-Si-Mg alloy (JIS AC4CH) at about 450 ° C is poured into a mold heated to about 480 ° C at a pressure of 0.5kg / cm ² to 0.7kg / cm ² by low pressure casting. The substrate 1 of the vehicle wheel shown in FIG. 8 was produced by taking it out from the mold after cooling. The draft γ was 60 °. Cutting was performed on the back surface of the spoke portion 6 of the base 1 to obtain a spoke portion 6 having a cross-sectional structure shown in FIG. The end portion B of the spoke portion 6 is an acute angle, and the inner angle θ is 30 °.

[Chamfering process]
By rotating the grindstone and pressing it against the end portion B, the endstone B is chamfered by moving the grindstone along the contour of the end portion B, and the first end portion 43 and the inner angle β having an inner angle α of 140 ° are obtained. A 70 ° second end 44 was formed (FIG. 2). The width of the chamfered surface 40 formed by the chamfering process was about 600 μm.

[Rounding process]
In this step, a brush was applied from the back side of the spoke portion, and the first end portion 43 and the second end portion 44 of the chamfered surface 40 formed in the chamfering step were rounded. A brush with a length of 100 mm was pressed against the end B after the chamfering process at a pressing pressure of 0.2 MPa, and moved relative to the wheel base in the circumferential direction. The processing time of the rounding process was standard time. The brush rubs the end portion B as shown in FIGS. 3 to 5, polishes the first end portion 43 and the second end portion 44 in a single step, and the first arc surface 45 and the first end portion at each position. Two arcuate surfaces 46 were formed. The radius of curvature R1 of the first arc surface 45 was 450 μm, and the radius of curvature R2 of the second arc surface 46 was 300 μm.

[Painting process]
A primer layer was formed by electrostatically coating a polyester powder coating on the wheel front and back surfaces. The coating film thickness was about 100 μm on the front surface and about 20 μm on the back surface. Thereafter, an acrylic color paint was sprayed onto the primer layer and sprayed onto the front and back surfaces of the wheel to form a color base layer. The dry film thickness was about 20 μm on both the front and back surfaces. Finally, a clear paint was applied to the wheel surface. The dry film thickness was about 20 μm. A coating film having a substantially uniform thickness was formed on the end portion B. As shown in FIG. 15, when the film thickness of the coating film on the first arc surface 45 is T1, and the film thickness of the coating film on the side surface 41 outside the spoke portion is T10, the ratio T1 / T10 between T1 and T10. Was calculated. Similarly, assuming that the film thickness T2 of the coating film on the second arc surface 46 and the film thickness of the coating film on the back surface 42 of the spoke portion are T20, the ratio T2 / T20 of T2 and T20 was calculated.

[Corrosion resistance test]
The wheel was installed in a neutral salt spray tester and a cast tester compliant with JIS Z 2371 (CASS test) and sprayed for 240 hours under the following conditions. After completion of spraying the salt water, the wheel was taken out, washed and wiped with water, and the change in the surface condition at the end B of the spoke portion, particularly the first and second arc surfaces and the vicinity thereof was visually observed.

Neutral salt spray test (SST: salt spray test) (conforms to JIS Z 2371)
・ Test solution: Sodium chloride 50 ± 5g / L, pH = 6.5-7.2
-Spraying room temperature: 35 ± 2 ° C
・ Amount of spray: 1.5 ± 0.5mL / h (80cm ² )

CASS test (copper accelerated acetic acid salt spray test) (conforms to JIS Z 2371)
・ Test solution: Sodium chloride 50 ± 5g / L
Copper (II) chloride 0.205 ± 0.015g / L
pH = 3.1-3.3 (Acetic acid acidity)
-Spraying room temperature: 50 ± 2 ℃
・ Amount of spray: 1.5 ± 0.5mL / h (80cm ² )

(Example 2)
A wheel was manufactured and a corrosion resistance test was performed under the same conditions as in Example 1 except that the internal angle α of the first end was 130 ° and the internal angle β of the second end was 80 °. The curvature radius R1 of the first arc surface 45 was 400 μm, and the curvature radius R2 of the second arc surface 46 was 300 μm.

Example 3
A wheel was manufactured and a corrosion resistance test was performed under the same conditions as in Example 1 except that the internal angle α of the first end was 120 ° and the internal angle β of the second end was 90 °. The curvature radius R1 of the first arc surface 45 was 350 μm, and the curvature radius R2 of the second arc surface 46 was 300 μm.

Example 4
The wheel was manufactured and the corrosion resistance test was performed under the same conditions as in Example 1 except that the internal angle θ was 60 °, the internal angle α of the first end was 130 °, and the internal angle β of the second end was 110 °. went. The radius of curvature R1 of the first arc surface 45 was 450 μm, and the radius of curvature R2 of the second arc surface 46 was 400 μm.

(Example 5)
The wheel was manufactured and the corrosion resistance test was performed under the same conditions as in Example 1 except that the internal angle θ was 60 °, the internal angle α of the first end was 150 °, and the internal angle β of the second end was 90 °. went. The radius of curvature R1 of the first arc surface 45 was 500 μm, and the radius of curvature R2 of the second arc surface 46 was 400 μm.

(Example 6)
The wheel was manufactured and the corrosion resistance test was performed under the same conditions as in Example 1 except that the internal angle θ was 60 °, the internal angle α of the first end portion was 160 °, and the internal angle β of the second end portion was 80 °. went. The curvature radius R1 of the first arc surface 45 was 550 μm, and the curvature radius R2 of the second arc surface 46 was 400 μm.

(Example 7)
The wheel was manufactured and the corrosion resistance test was performed under the same conditions as in Example 1, except that the internal angle θ was 80 °, the internal angle α of the first end portion was 170 °, and the internal angle β of the second end portion was 90 °. went. The curvature radius R1 of the first arc surface 45 was 550 μm, and the curvature radius R2 of the second arc surface 46 was 400 μm.

(Example 8)
The wheel was manufactured and the corrosion resistance test was performed under the same conditions as in Example 1 except that the internal angle θ was 80 °, the internal angle α of the first end was 150 °, and the internal angle β of the second end was 110 °. went. The radius of curvature R1 of the first arc surface 45 was 500 μm, and the radius of curvature R2 of the second arc surface 46 was 400 μm.

Example 9
A wheel was manufactured and a corrosion resistance test was performed under the same conditions as in Example 1 except that the internal angle θ was 80 ° and the internal angle β of the second end portion was 120 °. The radius of curvature R1 of the first arc surface 45 was 450 μm, and the radius of curvature R2 of the second arc surface 46 was 400 μm.

(Example 10)
Except that the rounding process time is 0.5 times the standard time, the radius of curvature R1 of the first arcuate surface 45 is 300 μm, and the radius of curvature R2 of the second arcuate surface 46 is 180 μm, the same as in Example 1. The wheel was manufactured under the conditions and the corrosion resistance test was performed.

(Example 11)
Example except that the internal angle θ is 60 °, the internal angle α of the first end is 150 °, the internal angle β of the second end is 90 °, and the processing time of the rounding process is 0.5 times the standard time. A wheel was prepared and a corrosion resistance test was performed under the same conditions as in No. 1. The curvature radius R1 of the first arc surface 45 was 200 μm, and the curvature radius R2 of the second arc surface 46 was 180 μm.

Example 12
Example, except that the internal angle θ is 80 °, the internal angle α of the first end is 170 °, the internal angle β of the second end is 90 °, and the processing time of the rounding process is 0.5 times the standard time. A wheel was prepared and a corrosion resistance test was performed under the same conditions as in No. 1. The curvature radius R1 of the first arc surface 45 was 250 μm, and the curvature radius R2 of the second arc surface 46 was 160 μm.

(Example 13)
The width of the chamfered surface 40 is about 1000 μm, the inner angle θ is 60 °, the inner angle α of the first end is 160 °, the inner angle β of the second end is 80 °, and the processing time of the rounding process is three times the standard time. Except for this point, a wheel was manufactured and a corrosion resistance test was performed under the same conditions as in Example 1. The radius of curvature R1 of the first arc surface 45 was 800 μm, and the radius of curvature R2 of the second arc surface 46 was 700 μm.

(Comparative Example 1)
The wheel was manufactured and the corrosion resistance test was performed under the same conditions as in Example 1 except that the internal angle θ was 30 °, the internal angle α of the first end portion was 105 °, and the internal angle β of the second end portion was 105 °. went. The curvature radius R1 of the first arc surface 45 was 150 μm, and the curvature radius R2 of the second arc surface 46 was 300 μm.

(Comparative Example 2)
The wheel was manufactured and the corrosion resistance test was performed under the same conditions as in Example 1 except that the internal angle θ was 60 °, the internal angle α of the first end was 120 °, and the internal angle β of the second end was 120 °. went. The curvature radius R1 of the first arc surface 45 was 150 μm, and the curvature radius R2 of the second arc surface 46 was 300 μm.

(Comparative Example 3)
The wheel was manufactured and the corrosion resistance test was performed under the same conditions as in Example 1 except that the internal angle θ was 80 °, the internal angle α of the first end portion was 130 °, and the internal angle β of the second end portion was 130 °. went. The curvature radius R1 of the first arc surface 45 was 150 μm, and the curvature radius R2 of the second arc surface 46 was 300 μm.

(Comparative Example 4)
A wheel was manufactured and a corrosion resistance test was performed under the same conditions as in Example 1 except that the internal angle α of the first end was 90 ° and the internal angle β of the second end was 120 °. The curvature radius R1 of the first arc surface 45 was 80 μm, and the curvature radius R2 of the second arc surface 46 was 150 μm.

(Comparative Example 5)
The wheel was manufactured and the corrosion resistance test was performed under the same conditions as in Example 1 except that the internal angle θ was 60 °, the internal angle α of the first end was 90 °, and the internal angle β of the second end was 150 °. went. The curvature radius R1 of the first arc surface 45 was 90 μm, and the curvature radius R2 of the second arc surface 46 was 300 μm.

(Comparative Example 6)
The wheel was manufactured and the corrosion resistance test was performed under the same conditions as in Example 1 except that the internal angle θ was 80 °, the internal angle α of the first end was 90 °, and the internal angle β of the second end was 170 °. went. The curvature radius R1 of the first arc surface 45 was 80 μm, and the curvature radius R2 of the second arc surface 46 was 300 μm.

(Comparative Example 7)
A wheel was manufactured and a corrosion resistance test was performed under the same conditions as in Example 1 except that the processing time of the rounding step was set to 7 times the standard time. The curvature radius R1 of the first arc surface 45 was 150 μm, and the curvature radius R2 of the second arc surface 46 was 800 μm.

(Comparative Example 8)
A wheel was manufactured and a corrosion resistance test was performed under the same conditions as in Example 4 except that the processing time of the rounding step was set to 5 times the standard time. The curvature radius R1 of the first arc surface 45 was 150 μm, and the curvature radius R2 of the second arc surface 46 was 900 μm.

(Comparative Example 9)
A wheel was manufactured and a corrosion resistance test was performed under the same conditions as in Example 7 except that the processing time of the rounding step was set to 6 times the standard time. The curvature radius R1 of the first arc surface 45 was 100 μm, and the curvature radius R2 of the second arc surface 46 was 900 μm.

Table 1 shows the working conditions and test results of the examples and comparative examples. Rust is most likely to occur at the end facing the window 7 on the outer side surface 41 of the spoke 6 or the end facing the window 7 on the back surface 42 of the spoke 6. Evaluation of rust in SST and CASS evaluation is as follows: ○ (good) when there is no rust at the end, △ (where rust is recognized but within an allowable range) where local rust is recognized, and continuous rust What was recognized was made into x (defect). At any end, it is determined that a vehicle wheel having excellent corrosion resistance is obtained when either evaluation is “good” in SST evaluation and CASS evaluation, or one is “good” and the other is “△”. A schematic diagram of local rust is shown in FIG. The extent of rust shown in FIG. 8 is defined as the local rust limit, and rust that has developed further is defined as continuous rust. Even if independent thread-like rust 51 occurs at the end facing the window 7 on the outer side surface 41 of the spoke 6 or the end facing the window 7 on the back surface 42 of the spoke 6, If there is, it does not affect the strength and design of the wheel. In particular, local rust generated at the end facing the window portion 7 on the back surface 42 of the spoke portion 6 is difficult to visually recognize from the front side of the disk surface, and thus the influence on the design is particularly small.

In any of the wheels of Examples 1 to 9 of the present invention, since a sufficiently thick coating film was formed at the edge of the spoke part, no rust was observed in either SST or CASS. In Examples 10 to 12, although local rust was slightly observed from the thin part of the coating film in R2, it was within an allowable range that does not affect the wheel performance. Since the rust of R2 is difficult to visually recognize from the front side of the disk surface, the influence on the design is particularly small. In Example 13, although generation | occurrence | production of rust was not recognized, since the processing time of the rounding process was long, productivity was inferior.

On the other hand, in the wheel of the comparative example, due to the small radius of curvature R1 of the first arc surface of the spoke part, the coating film of the first arc surface was particularly thin, resulting in poor corrosion resistance and continuous. Generation of rust was observed. In Comparative Examples 7 to 8, since the processing time of the rounding process was too long, R1 changed from increasing to decreasing, and a new end was formed by brushing. Generation of rust was observed in R1.

1 Wheel (base)
2 Rim part 3 Hub hole 4 Bolt hole 5 Hub part 6 Spoke part 7 Window part 8 Disk part 9 Brush 10 Brush free end 40 Chamfered surface 41 Side surface outside spoke part 42 Back surface 43 of spoke part First end part 44 2 end 45 first arc surface 46 second arc surface 50 coating 51 local rust 101 base forming process 102 heat treatment process 103 processing process 104 chamfering process 105 rounding process 106 pre-painting process 107 coating process R1 first arc surface Radius of curvature R2 radius of curvature α of the second arc surface inner angle β of the first end portion inner angle B of the second end portion end portion T1 film thickness of the coating film on the first arc surface T2 film thickness of the coating film on the second arc surface T10 Film thickness on the outer side of the spoke part T20 Film thickness on the back side of the spoke part

Claims

An annular rim portion for mounting a tire, a hub portion having a hub hole for connecting a vehicle wheel to an axle, and a spoke extending radially from the hub portion toward the rim portion and connecting the hub portion and the rim portion And a vehicle wheel manufacturing method comprising at least a window portion which is a space surrounded by the rim portion, the hub portion and the spoke portion,
A chamfering step for chamfering an end portion of the back surface and the side surface of the spoke portion located at a boundary between the back surface of the spoke portion and the window portion to form a chamfered surface;
A first rounding step of rounding a first end which is an end of the chamfered surface and a side surface of the spoke portion to form a first arc surface, and an end of the chamfered surface and the back surface of the spoke portion. At least a rounding step including a second rounding step of rounding the second end to form a second arc surface;
The vehicle wheel manufacturing method, wherein a curvature radius R1 of the first arc surface is larger than a curvature radius R2 of the second arc surface.
The method for manufacturing a vehicle wheel according to claim 1, wherein an inner angle α of the first end portion is larger than an inner angle β of the second end portion.
The rounding step
A brush disposing step of disposing a brush on the back side of the disk portion comprising the hub portion, the spoke portion, and the window portion;
Rubbing that forms the first arc surface and the second arc surface by moving the brush and the back surface of the disk portion relative to each other and rubbing the first end portion and the second end portion with the brush. Including at least a step,
The method for manufacturing a vehicle wheel according to claim 1 or 2, wherein a radius of curvature R1 of the first arc surface is made larger than a radius of curvature R2 of the second arc surface by the rubbing step.
The brush is a roll type brush having a rotating shaft,
The rubbing step is a step in which the rotation axis of the roll-type brush rotates in parallel with the back surface of the disc portion and is rubbed by relatively rotating concentrically with the back surface of the disc portion. 4. A method for manufacturing a vehicle wheel according to 3.
An annular rim portion for mounting a tire, a hub portion having a hub hole for connecting a vehicle wheel to an axle, and a spoke extending radially from the hub portion toward the rim portion and connecting the hub portion and the rim portion Vehicle wheel including at least a window portion that is a space surrounded by a portion, and the rim portion, the hub portion, and the spoke portion,
An end portion of the back surface and the side surface of the spoke portion located at a boundary between the back surface of the spoke portion and the window portion is a first arc surface that is an arc surface in contact with the side surface of the spoke portion, and the spoke portion. A second arc surface that is an arc surface in contact with the back surface of
The vehicle wheel, wherein a radius of curvature R1 of the first arc surface is larger than a radius of curvature R2 of the second arc surface.
The vehicle wheel according to claim 5, wherein a curvature radius R <b> 2 of the second arc surface is 200 μm or more and 600 μm or less.