Defective product determination method and device and non-transitory storage medium

Abstract

The present invention relates to a defective product determination method and device and a non-transitory storage medium. The defective product determination method for a vehicle wheel (100) comprises: as a positioning step, a controller (510) locates the lowest point on a welding mark generated by irradiation of a laser beam within a target range from the inner peripheral surface of a rim (10) to a position spaced inwardly by a prescribed distance in the radial direction of the vehicle wheel (100); and as a determination step, when a defective product determination condition is satisfied, the controller (510) determines that the vehicle wheel (100) is a defective product. The defective product determination condition includes the following condition as a necessary condition: the relative distance of the lowest point relative to the inner peripheral surface of the rim (10) in the radial direction of the vehicle wheel (100) is equal to or less than a reference distance.

Description

Technical Field

[0001] The technology disclosed herein relates to defective product determination for vehicle wheels. Background Art

[0002] Some vehicle wheels include a substantially cylindrical rim and a substantially circular disc fitted to the inner peripheral side of the rim. As a vehicle wheel of this type, a vehicle wheel is known in which the rim and the disc are joined together by arc welding. In arc welding, the amount of heat input per unit area is relatively large. Therefore, due to excessive input heat, thermal strain and residual stress may occur in the vehicle wheel, thereby deforming the vehicle wheel.

[0003] A vehicle wheel is known in which a rim and a disc are joined by laser welding (see, for example, Japanese Unexamined Patent Application Publication No. 5-329671 (JP 5-329671 A)). In laser welding, the rim and the disc can be joined with less input heat than in arc welding. That is, in laser welding, the thermal deformation of the rim and the disc is smaller than that in arc welding. Therefore, fatigue strength is improved. Therefore, the fitting length between the rim and the disc, which is necessary to ensure fatigue strength, can be reduced. As a result, in laser welding, the dimensional accuracy of the vehicle wheel can be improved, and its weight can be reduced.

[0004] Laser welded vehicle wheels are required to have high durability to maintain the driving safety of the vehicle. In the prior art, for example, a quality inspection is performed after the manufacture of vehicle wheels, so that the durability of each vehicle wheel is evaluated by a radial load durability test, and whether each vehicle wheel is a defective product is determined based on the evaluation result. Summary of the invention

[0005] In the prior art defective product determination method for vehicle wheels, it is necessary to perform a radial load durability test on all manufactured vehicle wheels. Therefore, there has been a need for a technique for efficiently performing defective product determination on sequentially manufactured vehicle wheels.

[0006] This specification discloses a technology that can solve the above-mentioned problems.

[0007] The technology disclosed in this article can be implemented in the following forms.

[0008] A first aspect of the present invention relates to a defective product determination method for a vehicle wheel. The defective product determination method for a vehicle wheel uses a defective product determination device. The defective product determination device includes a controller. The vehicle wheel includes a rim and a wheel disc, and the rim and the wheel disc are combined by irradiating a laser beam to a boundary between the rim and the wheel disc. The defective product determination method includes: as a positioning step, positioning by the controller a lowest point on a welding mark generated by irradiation of a laser beam within a target range from the inner peripheral surface of the rim to a position spaced inwardly by a prescribed distance in the radial direction of the vehicle wheel; and as a determination step, determining by the controller that the vehicle wheel is a defective product when a defective product determination condition is satisfied. The defective product determination condition includes the following condition as a necessary condition: the relative distance of the lowest point relative to the inner peripheral surface of the rim in the radial direction of the vehicle wheel is equal to or less than a reference distance.

[0009] The inventors have conducted extensive research, thereby newly discovering the correlation between the position of the lowest point on the weld mark generated by laser welding within a target range and the durability of the vehicle wheel. That is, in a defective product determination method for a vehicle wheel, when the relative distance of the lowest point with respect to the inner peripheral surface of the rim in the radial direction of the vehicle wheel (the inner side in the radial direction is positive) is equal to or less than a reference distance, the vehicle wheel is determined to be a defective product. According to the defective product determination method for a vehicle wheel, a vehicle wheel that is defective due to durability can be screened out based on the position of the lowest point on the weld mark generated by laser welding.

[0010] In the defective product determination method for a vehicle wheel, the defective product determination condition may further include a condition of the existence of continuous lowest points as a necessary condition. The continuous lowest points may be lowest points whose relative distance is equal to or less than a reference distance and are continuous over a reference length or more in the circumferential direction of the vehicle wheel.

[0011] For example, depending on the shape of the vehicle wheel or the determination accuracy required in the defective product determination for the vehicle wheel, when there is a lowest point whose relative distance is equal to or less than the reference distance and the length of the lowest point is relatively small, the determination that the vehicle wheel is a defective product should not be made based solely on the fact. In the defective product determination method for the vehicle wheel, the defective product determination conditions also include the condition of the existence of continuous lowest points as a necessary condition. The continuous lowest point is a part of the welding mark in which the lowest points whose relative distance is equal to or less than the reference distance are continuous over a reference length or more in the circumferential direction of the vehicle wheel. According to the defective product determination method for the vehicle wheel, the incidence of the situation where the vehicle wheel is erroneously determined to be a defective product based solely on the fact that the lowest point exists locally can be reduced.

[0012] In the defective product determination method for a vehicle wheel, the defective product determination condition may further include the following condition as a necessary condition: a total length of continuous lowest points is equal to or greater than a reference ratio of a bonding length between the rim and the disc.

[0013] For example, depending on the shape of the vehicle wheel or the determination accuracy required in the defective product determination for the vehicle wheel, when there are continuous lowest points and the total length of the continuous lowest points is relatively small, the determination that the vehicle wheel is a defective product should not be made based solely on the fact. In the defective product determination method for the vehicle wheel, the defective product determination condition also includes the following condition as a necessary condition: the total length of the continuous lowest points is equal to or greater than a reference ratio of the combined length between the rim and the wheel disc. According to the defective product determination method for the vehicle wheel, the incidence of the case where the vehicle wheel is erroneously determined to be a defective product based solely on the fact that the continuous lowest points exist can be reduced.

[0014] A second aspect of the present invention relates to a non-transitory storage medium. The non-transitory storage medium stores instructions that can be executed by one or more processors and cause the one or more processors to perform the following functions. The functions include: as a positioning process, positioning the lowest point on a welding mark generated by irradiation of a laser beam within a target range from the inner peripheral surface of the rim to a position spaced inwardly by a specified distance in the radial direction of the vehicle wheel. The vehicle wheel includes a rim and a wheel disc, and the rim and the wheel disc are combined by irradiating a laser beam to a boundary between the rim and the wheel disc. The functions include: as a determination process, when a defective product determination condition is satisfied, determining that the vehicle wheel is a defective product. The defective product determination condition includes the following condition as a necessary condition: the relative distance of the lowest point relative to the inner peripheral surface of the rim in the radial direction of the vehicle wheel is equal to or less than a reference distance. According to the above structure, a vehicle wheel that is defective due to durability can be screened out based on the position of the lowest point on the welding mark generated by laser welding.

[0015] A third aspect of the present invention relates to a defective product determination device for a vehicle wheel. The vehicle wheel includes a rim and a wheel disc, which are combined by irradiating a laser beam to a boundary between the rim and the wheel disc. The defective product determination device includes a controller. The controller is configured to locate the lowest point on a welding mark produced by irradiation of a laser beam within a target range from the inner peripheral surface of the rim to a position spaced a prescribed distance inward in the radial direction of the vehicle wheel. The controller is configured to determine that the vehicle wheel is a defective product when a defective product determination condition is met. The defective product determination condition includes the following condition as a necessary condition: the relative distance of the lowest point relative to the inner peripheral surface of the rim in the radial direction of the vehicle wheel is equal to or less than a reference distance. According to the above structure, a vehicle wheel defective due to durability can be screened out based on the position of the lowest point on the welding mark produced by laser welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals represent like elements, and in which:

[0017] Figure 1 is an XZ plane view schematically illustrating an appearance structure of the front side of a steel wheel 100 according to one embodiment;

[0018] Figure 2 is an explanatory diagram illustrating a portion of a manufacturing process of a steel wheel 100;

[0019] Figure 3 is a flow chart illustrating a portion of a method for manufacturing a steel wheel 100;

[0020] Figure 4 is an explanatory diagram schematically illustrating a cross-sectional structure near a laser welded portion 30;

[0021] Figure 5 is a graph illustrating the relationship between the durability of the steel wheel 100 and the relative laser distance;

[0022] Figure 6 is a graph illustrating the relationship between the fracture strength of the steel wheel 100 and the relative laser distance;

[0023] Figure 7 is an explanatory diagram illustrating a schematic structure of a defective product determination system 50 for a steel wheel 100; and

[0024] Figure 8 is a flowchart illustrating details of the defective product determination process. DETAILED DESCRIPTION

[0025] Structure of vehicle steel wheel 100

[0026] Figure 1 1 is an XZ plane view schematically illustrating the appearance structure of the front side of a vehicle steel wheel (hereinafter referred to as a “steel wheel”) 100 of the present embodiment. Figure 2 1 is an explanatory diagram illustrating a part of the manufacturing process of the steel wheel 100 . Figure 2 The laser welding device 300 and a portion of the steel wheel 100 are shown. Figure 1 The YZ cross-sectional structure at the position II-II in FIG. Each figure illustrates X, Y, and Z axes that are orthogonal to each other to determine the direction. For the sake of convenience herein, the Y-axis direction is a direction parallel to the rotation axis of the steel wheel 100, and is referred to as the "wheel axial direction" hereinafter, but the steel wheel 100 may actually be arranged in a direction different from such a direction. The radial direction of the steel wheel 100 is referred to as the "wheel radial direction", and the circumferential direction around the rotation axis of the steel wheel 100 is referred to as the "wheel circumferential direction". The same applies to Figure 3 and other subsequent figures. The steel wheel 100 is an example of a "vehicle wheel" in the claims.

[0027] The steel wheel 100 includes a substantially cylindrical rim 10, a substantially circular wheel disc 20 fitted to the inner peripheral side of the rim 10, and a laser welding portion 30 (see the laser welding method described later) that combines the rim 10 and the wheel disc 20 by laser welding. Figure 4 ). The steel wheel 100 of the present embodiment is a so-called two-piece steel wheel in which the rim 10 and the wheel disc 20 are provided separately. One side of the steel wheel 100 in the wheel axial direction (the positive Y-axis side as the front side of the steel wheel 100) is referred to as the "outer side" hereinafter. The other side of the steel wheel 100 in the wheel axial direction (the negative Y-axis side as the rear side of the steel wheel 100) is referred to as the "inner side" hereinafter. When the steel wheel 100 is mounted on a vehicle body (not shown), the outer side of the steel wheel 100 is opposite to the vehicle body, and the inner side of the steel wheel 100 is the vehicle body side. The outer surface of the steel wheel 100 is a designed surface.

[0028] like Figure 2 As illustrated, the rim 10 includes a pair of flange portions 110A and 110B, a pair of bead seat portions 120A and 120B, and a groove portion 130 .

[0029] The flange portions 110A and 110B are substantially annular when viewed in the wheel axial direction (Y-axis direction), and are positioned at both ends in the wheel axial direction of the rim 10. The flange portions 110A and 110B remain attached to a tire (not shown) of the steel wheel 100 without displacement in the wheel axial direction.

[0030] The bead seat portions 120A and 120B are arranged between the flange portions 110A and 110B in the axial direction of the wheel (Y-axis direction). Specifically, the bead seat portion 120A on the outside is adjacent to the inside of the flange portion 110A on the outside. The bead seat portion 120B on the inside is adjacent to the outside of the flange portion 110B on the inside. Each of the bead seat portions 120A and 120B has an outer peripheral surface substantially parallel to the axial direction of the wheel, and the tire is supported by the contact of the bead portion of the tire with the outer peripheral surface.

[0031] The groove portion 130 is arranged between the bead seat portions 120A and 120B in the wheel axial direction (Y-axis direction). When viewed in the wheel circumferential direction, the groove portion 130 has a shape that is recessed inwardly in the wheel radial direction relative to the bead seat portions 120A and 120B. Therefore, a groove (well) is formed on the outer peripheral side of the groove portion 130. Since the groove is formed in the rim 10, the tire can be easily attached to and detached from the steel wheel 100.

[0032] like Figure 1 and Figure 2 As illustrated, the wheel disc 20 includes a cap portion 210 , a hub attachment portion 220 , and a disc flange portion 230 .

[0033] The hub attachment portion 220 has a substantially circular shape and is positioned substantially at the center of the wheel disc 20 when viewed in the wheel axial direction (Y-axis direction). A hub hole 222 to which a wheel hub (not shown) of a vehicle body is coupled is formed substantially at the center of the hub attachment portion 220. Around the hub hole 222, a plurality of ( Figure 1 The support surfaces 226 are arranged at equal intervals in the wheel circumferential direction (see Figure 1 ).

[0034] A bolt hole 224 into which a fastening member (not shown) is inserted is formed through each support surface 226. Specifically, in the present embodiment, the bolt hole 224 of the support surface 226 is opened so that the diameter increases toward the outside. The peripheral portion of the bolt hole 224 of each support surface 226 protrudes toward the outside. Specifically, the peripheral portion of the support surface 226 is inclined so that the diameter increases toward the inside.

[0035] In the present embodiment, the fastening member includes, for example, a nut member having an internal thread and arranged on the outer side of the bolt hole 224 in the steel wheel 100, and a serration bolt having an external thread and arranged on the inner side of the bolt hole 224 in the steel wheel 100. The fastening member may include a hub bolt having an external thread and a bearing surface and arranged on the outer side of the bolt hole 224 in the steel wheel 100, and a hub having an internal thread. The fastening member may have another fastening structure (press-fit structure or the like) instead of a threaded engagement member such as a nut member and a bolt.

[0036] The outer peripheral surface of the peripheral portion of the bolt hole 224 in each bearing surface 226 is a tapered surface whose outer diameter decreases toward the bolt hole 224. When the hub attachment portion 220 is coupled to the vehicle body by fastening with a fastening member, a portion of the fastening member (e.g., a head of a bolt or a nut) is seated on the peripheral portion of the bolt hole 224 in the bearing surface 226.

[0037] The disc flange portion 230 has a substantially annular shape when viewed in the wheel axial direction (Y-axis direction), and is positioned on the outer peripheral edge of the wheel disc 20. The outer peripheral surface of the disc flange portion 230 is fitted to the inner peripheral surface of the groove portion 130 of the rim 10 (see FIG. Figure 2 ). The length of the fitting portion (disc flange portion 230 ) between the rim 10 and the disc 20 in the axial direction of the wheel is the “fitting length D1 ” between the rim 10 and the disc 20 .

[0038] The cap portion 210 is an annular portion positioned between the hub attachment portion 220 and the disc flange portion 230 and surrounding the hub attachment portion 220 when viewed in the wheel axial direction (Y axis direction). The cap portion 210 protrudes toward the outside. Specifically, the cap portion 210 includes an inner peripheral portion 212, a vertex portion 214, and an outer peripheral portion 216. When viewed in the wheel axial direction, the vertex portion 214 has a substantially annular shape and is positioned on the outer side of the hub attachment portion 220 and the disc flange portion 230 in the wheel axial direction. The inner peripheral portion 212 has a substantially annular shape and is positioned on the inner peripheral side of the vertex portion 214 when viewed in the wheel axial direction. The inner peripheral portion 212 is inclined to rise toward the outside as the distance from the outer peripheral edge of the hub attachment portion 220 to the vertex portion 214 decreases. The outer peripheral portion 216 has a substantially annular shape and is positioned on the outer peripheral side of the vertex portion 214 when viewed in the wheel axial direction. The outer peripheral portion 216 is inclined to rise toward the outside as the distance from the disc flange portion 230 to the apex portion 214 decreases.

[0039] The wheel disc 20 is positioned closer to the outside of the rim 10, and the outer peripheral surface (disc flange portion 230) of the wheel disc 20 is fitted to the inner peripheral surface of the groove portion 130 of the rim 10, and is integrated by laser welding (for example, fillet welding in which a laser beam L is irradiated to the vicinity of the boundary between the rim 10 and the wheel disc 20 for welding). As a result, a laser welded portion 30 (see the later-described Figure 4 In the present embodiment, the laser welding portion 30 is formed on the entire circumference or a portion of the wheel disc 20 .

[0040] Method for manufacturing steel wheel 100

[0041] Next, a manufacturing method for the steel wheel 100 will be described. Figure 3 is a flow chart illustrating a portion of a method for manufacturing a steel wheel 100. Figure 3 As shown, a preparation step (S110) is first performed to prepare a composite 100P (see Figure 2 ). The composite body 100P is obtained by fitting the wheel disc 20 into the rim 10, and is in a state before being joined by laser welding. The rim 10 can be manufactured, for example, by forming a flat steel plate. The wheel disc 20 can be manufactured, for example, by forming a flat steel plate.

[0042] Next, a laser welding step (S120) is performed to combine the inner peripheral surface of the rim 10 and the outer peripheral surface of the wheel disc 20 by laser welding. Specifically, the laser welding device 300 includes a controller 310 and a laser processor 320. The controller 310 includes a central processing unit (CPU) and a memory (not shown), and controls the operation of the laser processor 320. The laser processor 320 is, for example, a head separation type in which a body 312 and a head 314 are connected to each other via an optical fiber 316. The body 312 includes a laser light source such as an yttrium aluminum garnet (YAG) laser oscillator or a carbon gas laser oscillator. The head 314 is connected to the vehicle body 312 via the optical fiber 316. The laser beam L emitted from the laser light source of the body 312 is transmitted to the head 314 via the optical fiber 316, and irradiated from the head 314 to the welding target portion of the composite body 100P.

[0043] For example, Figure 2 As shown, the composite body 100P is held by a holding device (not shown) with its inner side facing upward, and rotated around the wheel axis. The laser welding device 300 is positioned above the composite body 100P, and a laser beam L from a head 314 is irradiated to the vicinity of the boundary between the rim 10 and the wheel disc 20 on the inner side of the steel wheel 100. As a result, the rim 10 and the wheel disc 20 are bonded by laser welding, and the steel wheel 100 is manufactured.

[0044] Principle of Defective Product Determination for Steel Wheel 100

[0045] Next, the principle of defective product determination for the steel wheel 100 will be described. The present inventors conducted extensive research and newly discovered the correlation between the target position of the laser beam L on the composite body 100P; and the position of the lowest point 32 on the weld mark (also referred to as a "weld bead" on the surface of the laser welded portion 30) generated due to laser welding, and the durability of the steel wheel 100. The lowest point 32 is the lowest point on the weld mark within a predetermined target range (in the case where the inner side of the steel wheel 100 faces upward). The target range is from the inner peripheral surface of the rim 10 to the inner side of the rim 10 in the radial direction of the wheel ( Figure 2 and described later Figure 4 For example, the lowest point 32 may be a portion of a welding mark formed on the wheel disc 20 side and moved backward in the wheel axial direction (Y-axis direction).

[0046] Specifically, if in the laser welding step ( Figure 3 If the target position of the laser beam L in S120 in the composite body 100P changes in the wheel radial direction (Z-axis direction), the shape of the weld mark formed on the steel wheel 100 may change, and the weld mark may have a lowest point 32 (for example, a dent in the weld mark). Since the target position of the laser beam L is farther from the inner peripheral surface 12 of the rim 10 when viewed in the wheel axial direction, the lowest point 32 tends to be formed at a position closer to the inner peripheral surface 12. In other words, as the relative distance of the target position of the laser beam L with respect to the inner peripheral surface 12 in the wheel radial direction (hereinafter referred to as the "relative laser distance", provided that the inner side in the wheel radial direction is positive) increases, the relative distance of the lowest point 32 with respect to the inner peripheral surface 12 (hereinafter referred to as the "relative distance ΔD1 of the lowest point 32", provided that the inner side in the wheel radial direction is positive) decreases (see the description described later). Figure 4 ). When the relative distance ΔD1 of the lowest point 32 is equal to or less than the predetermined reference distance ΔDt, the durability of the steel wheel 100 is significantly reduced.

[0047] The relationship between each of the relative distances ΔD1 of the relative laser position and the lowest point 32 and each of the durability and the fracture strength of the steel wheel 100 will be described with a specific example. Due to circumstances such as manufacturing variations, it is difficult to combine the rim 10 and the wheel disc 20 while always maintaining a constant relative laser distance. As a result, the relative laser distance may vary between a plurality of composite bodies 100P, and the relative laser distance of one composite body 100P may vary at a plurality of positions in the circumferential direction. Figure 4 3 is an explanatory diagram schematically illustrating a cross-sectional structure in the vicinity of a laser welded portion 30 . Figure 4The laser welding portion 30 (described later) is shown in the figure. Figure 7 The cross-sectional structures of five samples S1 to S5 of the steel wheel 100 near the portion X1 in FIG. 1 . The five samples S1 to S5 are manufactured under different conditions at the target position of the laser beam L in the laser welding step. That is, in the five samples S1 to S5, the relative laser distances are different from each other (see FIG. Figure 4 The fact that the relative laser distance is positive means that the target position of the laser beam L is relative to Figure 4 The approximate straight line L1 of the inner peripheral surface 12 in the wheel is on the inner side in the wheel radial direction (the positive Z axis side closer to the center of the wheel disc 20). The fact that the relative laser distance is a negative value means that the target position of the laser beam L is on the outer side in the wheel radial direction (the negative Z axis side closer to the rim 10) relative to the approximate straight line L1. The reference distance ΔDt can be determined based on the results of a radial load durability test, for example. In the present embodiment, the reference distance ΔDt is, for example, +0.3 millimeters (mm).

[0048] like Figure 4 As shown, in sample S1, the relative laser distance is -0.6 mm, and the relative distance ΔD1 of the lowest point 32 is substantially consistent with the prescribed distance ΔDh and is greater than the reference distance ΔDt. In sample S2, the relative laser distance is -0.3 mm, and the relative distance ΔD1 of the lowest point 32 is slightly greater than the reference distance ΔDt (+0.3 mm). In sample S3, the relative laser distance is substantially zero, and the relative distance ΔD1 of the lowest point 32 is slightly greater than the reference distance ΔDt. In sample S4, the relative laser distance is +0.3 mm, and the relative distance ΔD1 of the lowest point 32 is slightly greater than the reference distance ΔDt. In sample S5, the relative laser distance is +0.6 mm, and the relative distance ΔD1 of the lowest point 32 is less than the reference distance ΔDt.

[0049] Figure 5 is a graph illustrating the relationship between the durability of the steel wheel 100 and the relative laser distance. Figure 6 is a graph illustrating the relationship between the fracture strength and the relative laser distance of the steel wheel 100. The durability herein refers to the durability evaluated by the radial load durability test defined under JIS D 4103. The fracture strength herein refers to the load when the laser welded portion 30 or any other portion is fractured by applying a force to the wheel disc 20 in the wheel axial direction with the rim 10 fixed. Figure 5 and Figure 6 The horizontal axis in is the relative laser distance (mm). Figure 5 The vertical axis is the durability strength (unit: 10 4rotations), which is the rotation speed until the steel wheel 100 is broken or deformed in the radial load durability test. Figure 6 The vertical axis in is the breaking strength (kN) of the steel wheel 100 .

[0050] according to Figure 5 In the durability evaluation, the durability strengths of samples S1 to S4 are higher than the predetermined durability reference F, but the durability strength of sample S5 is significantly lower than the predetermined durability reference F. This means that when the relative laser distance is equal to or greater than the predetermined upper limit distance ( Figure 4 In the example of +0.6 mm), the relative distance ΔD1 of the lowest point 32 is equal to or smaller than the reference distance ΔDt, and the durability of the steel wheel 100 is significantly reduced. Figure 6 , in the fracture strength evaluation, the fracture strengths of all samples S1 to S5 are higher than the predetermined strength reference R. The fracture strength of sample S2 is lower than those of samples S3 and S4. The fracture strengths of samples S1 and S5 are even lower than that of sample S2. Figure 6 The evaluation results in mean that when the relative laser distance is greater than the upper limit distance, in addition to the durability of the steel wheel 100, the fracture strength is also reduced. According to the evaluation results of samples S1 and S2, it is considered that when the relative laser distance is equal to or less than the predetermined lower limit distance (in Figure 4 In the example of -0.3 mm), the dent in the welding mark is closer to the inner peripheral surface 12 of the rim 10 (see Figure 4 ), and the breaking strength of the steel wheel 100 is reduced.

[0051] According to the defective product determination method of the present embodiment described above, it is possible to make a determination as to whether the manufactured steel wheel 100 is a defective product that does not have the desired performance (durability and breaking strength) based on the position of the lowest point 32 on the welding trace generated due to laser welding. For example, the defective product determination method of the present embodiment is first performed on each of the manufactured steel wheels 100, and then a high-precision defective product determination method (e.g., radial load durability test) is performed only for the steel wheels 100 that are not determined to be defective products. As a result, the burden (man-hours, time, cost, etc.) of quality inspection of the steel wheels 100 can be reduced.

[0052] Structure for determining defective product of steel wheel 100

[0053] Figure 7 1 is an explanatory diagram illustrating a schematic structure of a defective product determination system 50 for a steel wheel 100. For example, the defective product determination system 50 determines whether the manufactured steel wheel 100 is a defective product by sequentially performing visual inspection on the steel wheel 100 during the quality inspection process on the production line. Figure 7As shown, the defective product determination system 50 includes an information processing device 500, an imaging unit 600, and the above-mentioned holding device. The information processing device 500 is an example of a "defective product determination device" in the claims.

[0054] The information processing device 500 includes a controller 510, a storage device 520, a display 530, an operation input device 540, and an interface 550. These components are communicably connected to each other via a bus 560.

[0055] For example, the display 530 is a liquid crystal display, and displays various images and various types of information. For example, the operation input device 540 includes a keyboard, a mouse, a button, and a microphone, and receives human operations and instructions. In the present embodiment, the display 530 includes a touch panel used as the operation input device 540. For example, the interface 550 includes a local area network (LAN) interface and a universal serial bus (USB) interface, and communicates with other devices (imaging unit 600, etc.) through wires or by wireless devices.

[0056] The storage device 520 includes, for example, a read-only memory (ROM), a random access memory (RAM), and a hard disk drive (HDD), and is used to store various types of data and programs, and is used as a work area and a temporary data storage area for executing various programs. Specifically, the storage device 520 stores a defective product determination program (PGM) 522. The defective product determination PGM 522 is a computer program for executing a process (defective product determination processing described later) of determining whether the steel wheel 100 is a defective product.

[0057] For example, the controller 510 includes a CPU, and controls the operation of the information processing device 500 by executing a computer program read from the storage device 520. For example, the controller 510 reads and executes the defective product determination PGM 522 in the storage device 520 to perform the defective product determination process described later. The controller 510 acts as a locator 512 and a determiner 514 when performing the defective product determination process. The functions of these components will be described according to the description of various processes described later.

[0058] The imaging unit 600 (e.g., a three-dimensional (3D) digital camera) can acquire a three-dimensional captured image of the surface shape of the object by, for example, an optical cutting method. The imaging unit 600 is arranged at a position where the vicinity of the welding mark on the steel wheel 100 held by the holding device can be imaged. The imaging unit 600 sequentially images the welding mark on the steel wheel 100 rotated by the holding device at predetermined intervals over the entire circumference. The captured image data fragments on the welding mark at a plurality of points (e.g., 6400 points) imaged by the imaging unit 600 are sequentially stored in the storage device 520 via the interface 550 of the information processing device 500.

[0059] Figure 8 3 is a flowchart illustrating the details of the defective product determination process. When the defective product determination process starts, the locator 512 locates the lowest point 32 on the welding trace, such as Figure 8 Specifically, the locator 512 determines the position of the lowest point 32 on the welding mark based on the image data captured at each point on the steel wheel 100 (S210). S210 is an example of the "locating step" and the "locating process" in the claims.

[0060] More specifically, the locator 512 measures the height difference of the shape of the welding mark based on the captured image data, and locates the lowest point 32 (in the case where the inner side of the steel wheel 100 faces upward) within the above-mentioned target range based on the measurement result (S210). For example, the prescribed distance ΔDh within the target range is preferably 90% or less of the width of the welding mark in the radial direction of the wheel (bead width), and more preferably 60% or less of the width of the welding mark. In the present embodiment, the prescribed distance ΔDh is, for example, 0.7 mm. By setting this prescribed distance ΔDh, the occurrence rate of a case where, for example, the original shape of the steel wheel 100 is erroneously determined as the lowest point 32 (a dent in the welding mark) can be reduced.

[0061] Next, the defective product determination PGM 522 determines whether the defective product determination condition is satisfied based on the positioning result from the locator 512. When a determination is made that the defective product determination condition is satisfied, the steel wheel 100 is determined to be a defective product (S220 to S260). S220 to S260 are examples of "determination step" and "determination processing" in the claims.

[0062] Specifically, when determining the position of the lowest point 32 in S210, the determiner 514 calculates the relative distance of the position of the lowest point 32 relative to the inner peripheral surface 12 of the rim 10, and determines the relative distance as the relative distance ΔD1 of the lowest point 32 (S220). Next, the determiner 514 determines whether the first condition that the relative distance ΔD1 of the lowest point 32 is equal to or less than the reference distance ΔDt is satisfied (S230). When the determiner 514 determines that the first condition is satisfied (S230: Yes), the determiner 514 determines whether the second condition that there are continuous lowest points is satisfied based on, for example, image data captured over the entire circumference of the steel wheel 100 (S240). The continuous lowest points are portions in which the lowest points 32 having the relative distance ΔD1 equal to or less than the reference distance ΔDt are continuous over a reference length (e.g., 5 mm) or more in the wheel circumferential direction. When the determiner 514 determines that the second condition is satisfied (S240: Yes), the determiner 514 determines whether the third condition is satisfied, that is, the total length of the continuous lowest points is equal to or greater than the reference ratio (for example, 60%) of the bonding length between the rim 10 and the disc 20 (S250). The bonding length between the rim 10 and the disc 20 is the total length of the bonding (welding) portion between the rim 10 and the disc 20 in the circumferential direction of the wheel. In the present embodiment, the rim 10 and the disc 20 are bonded over the entire circumference of the disc 20. Therefore, the bonding length between the rim 10 and the disc 20 is equal to the length of the entire circumference of the disc 20. In a structure in which the rim 10 and the disc 20 are bonded at a plurality of bonding portions located away from each other in the circumferential direction of the wheel, the bonding length between the rim 10 and the disc 20 is the sum of the lengths of the welding portions in the circumferential direction of the wheel. When the determiner 514 determines that the third condition is satisfied (S250: Yes), the currently inspected steel wheel 100 is determined to be a defective product because the durability is lower than the durability reference F (S260), and the defective product determination process is terminated.

[0063] When the determiner 514 determines that any one of the first to third conditions is not satisfied ( S230 : No, S240 : No, or S250 : No), the determiner 514 terminates the defective product determination process without determining that the steel wheel 100 is a defective product.

[0064] Effects of the Embodiments

[0065] In the above-described defective product determination method for the steel wheel 100 according to the present embodiment, when the defective product determination conditions including the necessary condition that the relative distance ΔD1 of the lowest point 32 is equal to or smaller than the reference distance ΔDt (first condition) are satisfied (in Figure 8In the embodiment, the steel wheel 100 having defects due to durability can be screened out based on the position of the lowest point 32 on the welding mark generated by laser welding.

[0066] For example, depending on the shape of the steel wheel 100 or the determination accuracy required in the defective product determination for the steel wheel 100, when the lowest point 32 exists and the length of the lowest point 32 is relatively small, the determination that the steel wheel 100 is a defective product should not be made based on this fact alone. In the present embodiment, the defective product determination condition also includes the condition (second condition) of the presence of continuous lowest points as a necessary condition (see Figure 8 According to the present embodiment, the occurrence rate of the steel wheel 100 being erroneously determined as a defective product based only on the fact that the lowest point 32 exists locally can be reduced.

[0067] For example, depending on the shape of the steel wheel 100 or the determination accuracy required in the defective product determination for the steel wheel 100, when there are continuous lowest points and the total length of the continuous lowest points is relatively small, the determination that the steel wheel 100 is a defective product should not be made based solely on this fact. In the present embodiment, the defective product determination condition also includes the following condition (third condition) as a necessary condition: the total length of the continuous lowest points is equal to or greater than the reference ratio of the bonding length between the rim 10 and the wheel disc 20 (see Figure 8 According to the present embodiment, the occurrence rate of the steel wheel 100 being erroneously determined as a defective product based only on the fact that continuous minimum points exist can be reduced.

[0068] The technology disclosed herein is not limited to the above-described embodiments, and can be modified into various forms without departing from the gist of the technology. For example, the following modifications are possible.

[0069] The structure of the steel wheel 100 in the above-described embodiment is merely an example, and various modifications may be made. For example, the steel wheel 100 to be inspected has a structure in which the rim 10 and the wheel disc 20 are laser welded over the entire circumference, but may also have a structure in which the rim 10 and the wheel disc 20 are partially not welded in the circumferential direction.

[0070] In the above embodiment, the two-piece steel wheel 100 is exemplified as the vehicle wheel, but the vehicle wheel is not limited to this type of steel wheel. For example, the vehicle wheel may be a so-called three-piece wheel (which includes a wheel disc and a rim including two parts, which are an outer rim and an inner rim), or may be a wheel other than a steel wheel (for example, an aluminum wheel).

[0071] The manufacturing method for the steel wheel 100 in the above-described embodiment is merely an example, and various modifications may be made. For example, the defective product determination condition does not need to include at least one of the second condition and the third condition. Figure 8 In the process, the determiner 514 does not need to perform at least one of the processes of S240 and S250. For example, when the determiner 514 determines that the first condition is satisfied (S230: Yes), the determiner 514 may determine that the product is defective (S260) and terminate the defective product determination process.

Claims

1. A defective product determination method for a vehicle wheel (100) using a defective product determination device (500), the defective product determination device (500) comprising a controller (510), the vehicle wheel (100) comprising a rim (10) and a wheel disc (20), the rim (10) and the wheel disc (20) being combined by irradiating a laser beam to a boundary between the rim (10) and the wheel disc (20), The defective product determination method is characterized by comprising: As a positioning step, the controller (510) positions the lowest point on the welding mark generated by irradiation of the laser beam within a target range from the inner peripheral surface of the rim (10) to a position spaced a prescribed distance inward in the radial direction of the vehicle wheel (100); and As a determination step, when a defective product determination condition is met, the controller (510) determines that the vehicle wheel (100) is a defective product, and the defective product determination condition includes the following condition as a necessary condition: the relative distance of the lowest point in the radial direction of the vehicle wheel (100) relative to the inner peripheral surface of the rim (10) is equal to or less than a reference distance.

2. The defective product determination method for the vehicle wheel (100) according to claim 1, characterized in that: The defective product determination condition also includes a condition of the existence of continuous lowest points as a necessary condition, wherein the continuous lowest points are the lowest points whose relative distance is equal to or less than the reference distance and are continuous over a reference length or more in the circumferential direction of the vehicle wheel (100).

3. The defective product determination method for the vehicle wheel (100) according to claim 2, characterized in that: The defective product determination condition also includes the following condition as a necessary condition: the total length of the continuous lowest points is equal to or greater than a reference ratio of the combined length between the rim (10) and the wheel disc (20).

4. A non-transitory storage medium storing instructions that can be executed by one or more processors and cause the one or more processors to perform the following functions, characterized in that: The features include: As a positioning process, positioning the lowest point on a welding mark generated by irradiation of a laser beam within a target range from an inner peripheral surface of a rim (10) to a position spaced inwardly by a prescribed distance in a radial direction of a vehicle wheel (100), the vehicle wheel (100) comprising the rim (10) and a wheel disc (20), the rim (10) and the wheel disc (20) being combined by irradiating the laser beam to a boundary between the rim (10) and the wheel disc (20); and As a determination process, when a defective product determination condition is satisfied, the vehicle wheel (100) is determined to be a defective product, the defective product determination condition including the following condition as a necessary condition: the relative distance of the lowest point in the radial direction of the vehicle wheel (100) relative to the inner peripheral surface of the rim (10) is equal to or less than a reference distance.

5. A defective product determination device (500) for a vehicle wheel (100), the vehicle wheel (100) comprising a rim (10) and a wheel disc (20), the rim (10) and the wheel disc (20) being combined by irradiating a laser beam to a boundary between the rim (10) and the wheel disc (20), the defective product determination device (500) comprising a controller (510), wherein: The controller (510) is configured to locate the lowest point on the welding mark generated by irradiation of the laser beam within a target range from the inner peripheral surface of the rim (10) to a position spaced a prescribed distance inward in the radial direction of the vehicle wheel (100); and The controller (510) is configured to determine that the vehicle wheel (100) is a defective product when a defective product determination condition is satisfied, the defective product determination condition including the following condition as a necessary condition: the relative distance of the lowest point in the radial direction of the vehicle wheel (100) relative to the inner peripheral surface of the rim (10) is equal to or less than a reference distance.

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