Method for inspecting dissimilar metal joint, device for inspecting dissimilar metal joint, welding method, and welding system

Abstract

The invention provides an inspection method for a dissimilar metal joint, an inspection device for a dissimilar metal joint, a welding method, and a welding system, which can inspect the joint strength with high reliability when spot welding dissimilar metals to each other, can immediately inspect after welding, and are easy to automation. A method for inspecting a dissimilar metal joint by spot welding, at the position of a through-hole (11a), a plate group in which at least one steel first member (11) having the through-hole (11a) in the plate thickness direction and a non-ferrous metal second member (13) overlap each other, the protrusion height (H) of the weld metal (15) formed by spot welding from the surface of the first member (11) on the opposite side from the second member (13) is measured, and the welding state of spot welding is determined on the basis of the measured protrusion height (H).

Description

Technical Field

[0001] The present invention relates to a method for inspecting a dissimilar metal joint, an inspection device for the dissimilar metal joint, a welding method and a welding system. Background Art

[0002] In the past, the safety of passengers in vehicles was improved, and the strength of vehicle bodies was increased for this purpose. On the other hand, against the backdrop of the deepening of global warming issues, the movement to improve the fuel efficiency of motor vehicles is accelerating. It is known that lightweighting of vehicle bodies is effective for improving fuel efficiency. As a countermeasure for lightweighting of vehicle bodies, attempts are being actively made to replace steel, which is currently the main material, with light metals such as aluminum and magnesium, which are lightweight raw materials. In order to combine steel and light metals, it is necessary to set up a portion for joining them, but compared with previous welding of materials of the same kind, welding of dissimilar materials is mostly difficult, and it becomes important to ensure the reliability and soundness of the welded parts.

[0003] Usually, for welded joints of structures including spot welding, inspections are performed after welding to ensure the reliability and soundness of the joints. This is also the same in the field of dissimilar material joining. For example, as a dissimilar material joining method of iron and aluminum using aluminum welding wire, a dissimilar metal arc spot welding method (hereinafter also referred to as DASW: Dissimilar Arc Spot Welding) has been developed (for example, refer to Patent Document 1). In addition, in addition to this, research is also being promoted on spot welding methods for dissimilar materials based on laser welding using a laser as a heat source and supplying welding wire to the laser irradiation part, and hybrid welding using laser and arc.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 52-114446

[0007] According to the above-mentioned DASW, spot welding methods based on laser welding and hybrid welding, steel and light metals such as aluminum can be firmly joined. However, in these joining methods and joining mechanisms, a standard joint inspection method has not been established. On the other hand, there are some inspection methods for joints based on resistance spot welding that have been widely used in the past. Destructive tests using chisels and non-destructive inspections of welds using ultrasonic flaw detection tests (UT: Ultrasonic Testing) are known. In addition, non-destructive inspections such as radiographic testing (RT: Radiographic Testing) and magnetic flaw detection tests (MT: Magnetic Particle Testing) are also known. However, in order to apply these methods to DASW, there are the following issues.

[0008] In the case of a destructive test using a chisel, damage to the weld and the base material is inevitable, and it is difficult to completely restore to the state after welding. In the case of an ultrasonic flaw detection test, it is difficult to make the probe contact due to the presence of protrusions in the weld of DASW, and it is also impossible to make the probe contact in a high temperature state after welding, so there are problems such as difficulty in immediate inspection, and in the case of aluminum weld metal as the object, there are often fine pores in the weld metal, making it difficult to obtain the desired reflected wave. In laser UT, the weld can be inspected without using a probe and without contact, but the above-mentioned problem about pores remains. In addition, there is temperature dependence in the propagation characteristics of ultrasonic waves in the weld, so it is difficult to apply immediate inspection after welding. In the radiation penetration test, the introduction of equipment that takes safety into consideration is indispensable. In addition, although it is aimed at confirming internal defects, it is difficult to determine the diameter of the nugget and the shape of the excess height, which become important. The magnetic flaw detection test is a method used for steel made of magnetic materials, and the expected inspection results cannot be obtained in dissimilar metal joining such as DASW. Summary of the invention

[0009] Problems to be solved by the invention

[0010] Therefore, the object of the present invention is to provide a method for inspecting dissimilar metal joints, an inspection device for dissimilar metal joints, a welding method and a welding system that can inspect the joint strength with high reliability when spot welding dissimilar metals to each other, and can perform immediate inspection after welding and can be easily automated.

[0011] Solutions to Solve Problems

[0012] The present invention is constituted by the following structure.

[0013] (1) A method for inspecting a dissimilar metal joint, the dissimilar metal joint being formed by spot welding a plate assembly consisting of at least one first member made of steel and having a through hole in the plate thickness direction and a second member made of nonferrous metal overlapping each other at the position of the through hole, wherein:

[0014] measuring a protrusion height of weld metal formed by the spot welding from a surface of the first member on the side opposite to the second member,

[0015] The welding state of the spot welding is determined based on the measured protrusion height.

[0016] (2) A welding method, wherein:

[0017] The welding method has the following characteristics:

[0018] A welding step of spot welding a plate assembly formed by overlapping at least one first member made of steel and having a through hole in the plate thickness direction and a second member made of nonferrous metal at the position of the through hole to form a dissimilar metal joint;

[0019] a measuring step of measuring at least one of a protrusion height of the weld metal formed by the spot welding from the surface of the first member on the side opposite to the second member and a protrusion height of the weld metal formed by the spot welding from the back surface of the second member on the side opposite to the first member;

[0020] a determination step of determining a welding state of the spot welding based on the measured protrusion height; and

[0021] The repairing step is to repair the welding position of the spot welding when the welding state of the spot welding is determined to be defective.

[0022] (3) An inspection device for a dissimilar metal joint, the dissimilar metal joint being formed by spot welding a plate assembly consisting of at least one first member made of steel having a through hole in the plate thickness direction and a second member made of nonferrous metal overlapping each other at the position of the through hole, wherein:

[0023] The inspection device for dissimilar metal joints comprises:

[0024] a height measuring unit that measures a protrusion height of weld metal formed by the spot welding from a surface of the first member on the side opposite to the second member; and

[0025] A determination unit determines a welding state of the spot welding based on the measured height.

[0026] (4) A welding system, wherein:

[0027] The welding system has:

[0028] (3) The inspection device for dissimilar metal joints; and

[0029] a welding device for joining the first member and the second member by the spot welding to form the dissimilar metal joint,

[0030] The welding system has a repair function of driving the welding device to repair the welded position of the spot welding determined to be defective when the welding state of the spot welding is determined to be defective.

[0031] Effects of the Invention

[0032] According to the present invention, when spot welding dissimilar metals, the joint strength can be inspected with high reliability. In addition, inspection can be performed immediately after welding, and automation is also easy. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a cross-sectional view showing the main parts of the dissimilar metal joining joint.

[0034] Figure 2 yes Figure 1 A top view of a dissimilar metal joining joint is shown.

[0035] Figure 3A The present invention is a process explanatory diagram showing the procedure for forming a dissimilar metal joint between a steel plate and an aluminum plate having a through hole.

[0036] Figure 3B The present invention is a process explanatory diagram showing the procedure for forming a dissimilar metal joint between a steel plate and an aluminum plate having a through hole.

[0037] Figure 3C The present invention is a process explanatory diagram showing the sequence of forming a dissimilar metal joint between a steel plate and an aluminum plate having a through hole.

[0038] Figure 4 This is a schematic diagram of the structure of a welding system including a welding robot provided with a height measuring device.

[0039] Figure 5 This is an explanatory diagram schematically showing a state in which the height of a dissimilar metal joint of a joint body is measured by a height measuring device.

[0040] Figure 6 This is a flowchart showing the basic procedure of a method for inspecting a dissimilar metal joint.

[0041] Figure 7 This is an explanatory diagram schematically showing a state in which the height of a dissimilar metal joint of a joint body is measured from the front side and the back side using a height measuring device.

[0042] Fig. 8A This is a cross-sectional photograph of a cut surface of a dissimilar metal joint that was determined to be normal.

[0043] Figure 8B This is a cross-sectional photograph of a cut surface of a dissimilar metal joint judged to be defective.

[0044] Fig. 9 This is a graph showing an altitude curve obtained using measurement data from an altitude meter.

[0045] Fig.10 It is a graph showing the height curve and the reference height distribution.

[0046] Fig.11 It is a graph showing the height curve and the reference height distribution.

[0047] Fig.12 It is an explanatory diagram showing a height curve when the through hole of the first member is measured before welding.

[0048] Fig.13 It is shown based on Fig.12 An illustration of the reference height distribution created using the center line shown.

[0049] Fig.14 The height curve is shown in Figure 1. Fig.13 1 is an explanatory diagram of a case where a reference height distribution is compared.

[0050] Fig.15 The height curve is shown in Figure 1. Fig.13 1 is an explanatory diagram of a case where a reference height distribution is compared.

[0051] Fig.16 It is an explanatory diagram showing a height curve when the protruding shape of the welded portion is measured after welding.

[0052] Fig.17 It is shown based on Fig.15 An illustration of the reference height distribution created using the center line shown.

[0053] Fig.18 This is an explanatory diagram showing a state in which the positional relationship of representative points extracted from a measured height curve is compared with a reference.

[0054] Fig.19 This is an explanatory diagram showing a state in which the positional relationship of representative points extracted from a measured height curve is compared with a reference.

[0055] Fig. 20 It is an explanatory diagram showing a height curve of weld metal measured after welding and a height curve measured at a through hole as a welding position before welding.

[0056] Fig.21 This is an explanatory diagram for explaining the volume of weld metal formed in the through-hole of the first member after welding.

[0057] Fig. 22 It is an explanatory diagram showing a cross-sectional view and a front view of weld metal that joins a first member and a second member.

[0058] Fig.23 It is an explanatory diagram showing the outer edge shape of the surface excess of the weld metal in the XY plane.

[0059] Fig.24 It is an explanatory diagram showing the outer edge shape of the surface excess of the weld metal in the XY plane.

[0060] Fig.25 The flowchart shows the inspection procedure including detection of the position of the preliminary hole, welding, height measurement, and repairing of the welded portion after defect determination.

[0061] Fig.26 It shows that Fig.25 The flowchart shown here changes the inspection procedure from one point at a time to a multi-point inspection.

[0062] Description of Reference Numerals

[0063] 11 First Component

[0064] 11a Through hole

[0065] 11b, 11c Eaves

[0066] 13 Second component

[0067] 13a Through section

[0068] 15 Weld Metal

[0069] 15a Surface excess

[0070] 15b Back side height

[0071] 15c Shaft

[0072] 17 Welding torch

[0073] 19 Welding wire

[0074] 21 Altimeter

[0075] 23. Welding Robot

[0076] 25 Front shaft

[0077] 27 Conjugate

[0078] 31 Control device

[0079] 33. Determination device (determination unit)

[0080] 35 Robot Control Unit

[0081] 37 Welding Control Department

[0082] 100 Dissimilar metal joints

[0083] 200 Welding System

[0084] Ak Arc

[0085] At Inspection Area

[0086] G Shielding gas

[0087] LB Laser. DETAILED DESCRIPTION

[0088] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this specification, a dissimilar metal joint formed by overlapping a steel plate having a through hole and an aluminum plate as a nonferrous metal and joining them to each other by arc spot welding (MIG welding) is described as an example, but the structure and material of the joint are not limited thereto and various changes can be made.

[0089] <Structure of dissimilar metal joint>

[0090] Figure 1 : is a cross-sectional view showing the main part of the dissimilar metal joint. The dissimilar metal joint 100 includes: a first member 11, which is made of a steel plate and has a through hole 11a in the plate thickness direction; a second member 13, which is made of a nonferrous metal; and a weld metal 15. The second member 13 shown here is made of aluminum or an aluminum alloy (hereinafter, also referred to as an aluminum material). The first member 11 and the second member 13 are not limited to plate materials, and may also be die castings, extruded materials, etc. The weld metal 15 is formed by arc spot welding described later, and the overlapping first member 11 and the second member 13 are joined to each other. The weld metal 15 is formed by melting a joining auxiliary member (welding wire) and joined to the second member 13. The weld metal 15 of this structure forms a weld leak (back side bead) from the back side (lower surface) of the second member 13, but the back side bead may not be provided. The welding wire forming the joining auxiliary member is preferably made of the same material as the second member 13. In the case of this structure, it is formed by a welding wire made of an aluminum alloy.

[0091] Figure 2 yes Figure 1 The top view of the dissimilar metal joint 100 shown in FIG. The weld metal 15 is formed into a substantially circular shape in a top view by arc spot welding, and has a surface excess height 15a that wets and spreads on the surface (upper surface) of the first member 11. In addition, the second member 13 may be penetrated from the through hole 11a of the first member 11, and have a back surface excess height 15b formed by protruding from the back surface of the second member 13. In this way, the first member 11 is sandwiched between the surface excess height 15a arranged on one end side in the plate thickness direction and the second member 13 arranged on the other end side of the first member 11 and connected to the weld metal 15, and is joined to the second member 13. It should be noted that the formation of the back surface excess height 15b as described above is arbitrary, and the weld metal 15 may not protrude from the second member 13.

[0092] The dissimilar metal joint 100 can obtain sufficient joint strength even without the back side reinforcement 15b. In addition, by omitting the back side reinforcement 15b, it can contribute to the weight reduction of the joint. In addition, when the back side reinforcement 15b is provided, the larger the back side reinforcement 15b is, the higher the joint strength can be. However, since there is interference with other parts, an increase in the consumption of consumable materials, and an increase in weight, it can be set to balance the above matters according to the situation.

[0093] The first member 11 may be a plate group formed by overlapping a plurality of steel plates having through holes at the same position in addition to a single steel plate. In addition, the shape of the through hole 11a is not limited to a circle, and may be any shape. In addition, the second member 13 may be other light metals such as magnesium, magnesium alloy, etc. in addition to aluminum.

[0094] <Welding of dissimilar metal joints>

[0095] Figure 3A to Figure 3C The process diagram shows the order of forming the dissimilar metal joint 100 of the steel plate and the aluminum plate having a through hole. Figure 1 , Figure 2 The dissimilar metal joint 100 shown in the figure is firstly Figure 3A As shown, the first member 11 and the second member 13 are overlapped in the plate thickness direction.

[0096] like Figure 3B As shown in FIG. 1 , a welding torch 17 is arranged toward the recess formed by the through hole 11a (also referred to as the preparatory hole) of the overlapped first member 11 and the second member 13, and an arc Ak is generated from the tip of the welding wire 19 held by the welding torch 17 to melt the welding wire 19. This arc welding is performed in an atmosphere of a shielding gas G. The exposed portion inside the preparatory hole of the second member 13 is melted by the arc Ak, and the welding wire 19 is welded. Figure 3C As shown in the figure, a through portion 13a is formed that penetrates in the plate thickness direction. In this way, the prepared hole of the first member 11 and the through portion 13a of the second member 13 are filled with the welding metal formed by melting the welding wire 19 and the molten metal formed by melting the second member 13. In addition, a surface excess 15a is formed on the outside of the through hole 11a of the first member 11 where the molten metal wets and spreads radially outward.

[0097] As the above-mentioned arc welding, (a) consumable electrode type gas shielded arc welding is used, but in addition to this, other welding methods such as (b) non-gas shielded arc welding, (c) consumable electrode type tungsten inert gas shielded arc welding, (d) plasma arc welding, (e) covered arc welding, etc. may also be used.

[0098] (a) The consumable electrode gas shielded arc welding method is generally referred to as MAG (Metal Active Gas) welding or MIG (Metal Inert Gas) welding, and is a method of using a solid wire or a flux-cored wire as a filler and an arc-generating consumable electrode, and using an inactive gas such as CO2, Ar or He to block the weld from the atmosphere to form a sound weld.

[0099] (b) Gas-free arc welding is also called self-shielded arc welding, and uses a special flux-cored wire as both a filler and arc-generating melting electrode. This welding method does not require shielding gas G, resulting in a more robust weld.

[0100] (c) Tungsten inert gas welding is a type of gas shielded arc welding and is a non-melting electrode type, and is also commonly referred to as TIG (Tungsten Inert Gas) welding. As the shielding gas G, an inert gas such as Ar or He is used. An arc is generated between the tungsten electrode and the base material, and the filler wire is fed from the side to the arc. Usually, the filler wire is not energized, but there is also a hot wire method TIG in which the melting speed is increased by energizing. In this case, no arc is generated in the filler solder.

[0101] (d) The plasma arc welding method has the same principle as TIG, but it is a welding method that increases the arc force by constricting the arc through dual systematization and speeding up of the gas.

[0102] (e) Covered arc welding is an arc welding method in which a covered arc welding rod having a metal core wire coated with flux is used as a filler, and shielding gas is not required.

[0103] It should be noted that, although the case of spot welding using arc is described here, it is not limited to arc, and spot welding based on laser welding or mixed welding using both laser and arc can also be used. In this case, high-precision spot joining can be performed with better controllability.

[0104] <Inspection of dissimilar metal joints>

[0105] As a height measuring device for measuring the height of the weld metal 15 after spot welding as described above, a contact altimeter, a non-contact laser displacement meter, an image sensor (camera), etc. can be used. In the image sensor, the height can be calculated using the shooting data captured from multiple directions using a sensor, or the height can be calculated based on information from more than two sensors like a binocular camera or a 3D camera. Although a contact altimeter is difficult to contact with the high-temperature part and is not facing the measurement just after welding, it has high reliability because it can directly measure the height. On the other hand, non-contact laser displacement meters, image sensors, etc. can also measure the high-temperature weld part just after welding.

[0106] As measurement methods, there can be cited a method of measuring the displacement (height) of a certain point, a method of repeatedly measuring the displacement of a certain point and measuring the displacement of multiple points by shifting the measurement position, a method of obtaining the displacement distribution of a certain line, a method of repeatedly obtaining the displacement distribution of a line and measuring the displacement distribution of multiple lines by shifting the measurement position, a method of obtaining a three-dimensional displacement distribution at the same time, etc.

[0107] The various measured data may be subjected to various filtering processes such as averaging filtering and Gaussian filtering, data elimination processing, etc. as pre-processing in order to remove noise, speed up data processing, etc.

[0108] The measurement data obtained by height measurement may be two-dimensional (e.g., x-coordinate and height) data, or three-dimensional (e.g., x-, y-coordinate and height) data. These two-dimensional or three-dimensional data may be processed directly, or low-dimensional processing may be performed. For example, the height value on a specific line in the three-dimensional data may be extracted as two-dimensional data, thereby simplifying subsequent processing. As a method for selecting a line, it may be a diameter line passing through the center of the through hole 11a (prepared hole) of the first member 11, or a line with a pre-set height value, or a line selected by a specific algorithm. In addition, multiple lines including the various lines mentioned above may be selected.

[0109] <Welding system>

[0110] The height measuring device 21 may be mounted on a welding device that performs spot welding.

[0111] Figure 4 2 is a schematic diagram of a welding system 200 including a welding robot 23 provided with a height measuring device 21. The welding robot 23 shown as an example is a multi-axis robot, and a welding torch 17 is provided on a distal end axis 25 of a robot arm.

[0112] Figure 4 The welding system 200 shown is an example of a welding system for performing the aforementioned (a) consumable electrode type gas shielded arc welding. The welding system 200 includes: a welding robot 23, which includes a height meter 21; a control device 31; and a determination device (determination unit) 33. The control device 31 includes a robot control unit 35 for driving the welding robot 23 and a welding control unit 37 for controlling a power supply device (not shown) and a welding wire feeding device (not shown) for feeding the welding wire to the welding torch 17. The determination device 33 may also be included in the control device 31. In addition, in addition to being arranged in the structure of the welding robot 23, the height meter 21 may be fixed at a specific position, or may be arranged in other driving mechanisms that operate the height meter 21.

[0113] The position and posture of the welding torch 17 can be freely set by controlling the robot arm. The height gauge 21 is supported on the front end shaft 25 of the robot arm or near the front end shaft 25, and the measuring position and measuring direction can be freely set by driving and controlling the robot arm in the same way as the movement of the welding torch 17. The movement of the robot arm during measurement can also be a movement within the area of ​​the two-dimensional plane. In this way, when the front end shaft 25 of the robot arm holding the welding torch 17 is equipped with the height gauge 21, the welding robot 23 has the functions of welding and inspection at the same time, so the cost of setting space and equipment investment can be reduced. In addition, it is easy to perform an immediate inspection after welding, which also has the effect of shortening the production cycle time.

[0114] The welding robot 23 is not limited to a multi-axis robot, and may also be a movable worktable with a single axis or two orthogonal axes. For example, the height gauge 21 may be installed on the movable worktable, and the measurement may be performed by scanning the welded joint. In addition, the height gauge 21 may be fixed to an immovable fixed portion, and the welded joint to be measured may be transported to the position of the height gauge 21 for measurement.

[0115] The welding robot 23 and the control device 31 function as a welding device for spot welding. In addition, the welding robot 23, the control device 31, the determination device 33, and the height measuring device 21 function as an inspection device for measuring the protruding height of the weld metal at the welded portion and determining the welding state.

[0116] Figure 5 This is an explanatory diagram schematically showing the situation of measuring the height of the dissimilar metal joint 100 of the joint 27 using the height measuring device 21. The joint 27 shown here is a joint of a first member 11 made of steel having a top-hat-shaped cross-section perpendicular to the longitudinal direction and a second member 13 made of aluminum in a flat plate shape. The pair of flanges 11b and 11c of the first member 11 have a plurality of through holes 11a, and the dissimilar metal joint 100 is formed at a plurality of locations in the region where the flanges 11b and 11c overlap with the second member 13. Figure 5 , a state is shown in which a dissimilar metal joint 100 is formed by spot welding at one location of one end portion in the longitudinal direction of the flange portion 11 b on the front side.

[0117] <Inspection Order>

[0118] Next, the procedure of the inspection method of the above-mentioned dissimilar metal joint 100 will be described. Figure 6 1 is a flowchart showing the basic procedure of the inspection method of the dissimilar metal joint 100. Figure 5 In the example shown in the figure, first, the first member 11 and the second member 13 are overlapped as described above, and based on the control device 31 ( Figure 4) is instructed to perform spot welding at the position of the through hole 11a (preparatory hole) (S1).

[0119] Next, the control device 31 uses the height measuring device 21 to measure the height H ( Figure 1 ) is measured (S2). Specifically, the robot control unit 35 drives the welding robot 23, and Figure 5 A height measuring device 21 is disposed at the height measuring position shown. The height measuring device 21 exemplified here is a laser displacement meter, and measures the height H of the weld metal 15 by irradiating a predetermined inspection area At including the weld metal 15 at the measuring position with laser light LB.

[0120] The measurement result obtained by the height measuring device 21 is input to the determination device 33. The determination device 33 compares the obtained measurement data of the height H with a preset reference, and determines whether the dissimilar metal joint 100 satisfies the desired conditions (S3). The determination device 33 determines that the joint 100 is normal if the conditions are satisfied (S4), and determines that the joint 100 is defective if the conditions are not satisfied (S5).

[0121] The comparison of the measured data obtained here with the reference may be performed by capturing information on the height distribution of the weld metal 15 and comparing it with a preset threshold distribution, or by comparing the maximum value of the height H or the height at a preset position with a preset threshold. In addition to the measurement of the height H, the excess height portion of the weld metal 15 may be extracted by using the reflectivity from the measurement position when a laser displacement meter is used, or by using the brightness of a captured image when an image sensor is used, and the width W ( Figure 1 ) to determine whether it is normal or defective. In addition, when processing such as the first-order differential (difference) and the second-order differential (difference of differential) of the measured data is performed, the characteristic value of the shape of the weld metal 15 is accurately captured, thereby enabling accurate judgment.

[0122] As described above, in steps S3 to S5, the determination device 33 determines the soundness of the dissimilar metal joint 100 using the measurement data or the data appropriately processed after the measurement. For the determination of the soundness, the representative values ​​of various characteristic quantities such as the height H and the width W of the surface reinforcement 15a of the weld metal 15, which is the reinforcement part, may be calculated based on the data obtained by the height measuring device 21, and when each representative value satisfies the pre-set conditions, it is determined that the measured dissimilar metal joint 100 is a good joint. The determination conditions at this time can be changed to appropriate conditions according to the plate group used for the joint (material type, heat treatment, plate thickness and other conditions), the required joint performance and the like. For example, as the height H of the reinforcement, the maximum value of the height measurement data, the height at the center of the width W of the reinforcement, or the height at any specific position may be used. In addition, the above-mentioned multiple heights or height distributions may be used. In addition, in addition to the height H and the width W of the reinforcement, the contact angle, the center of gravity and the like of the weld metal 15 may be used for determination. The volume of the excess height portion of the weld metal 15 may be calculated based on the acquired measurement data, and the calculated volume value may be used for determination.

[0123] In this way, according to the above-mentioned inspection method of the dissimilar metal joint 100 by measuring the height of the excess height portion, the inspection can be performed without damaging the welded portion and the base material, and even in the high temperature state just after welding, the inspection can be performed immediately. In addition, no particularly large-scale equipment is required, and a simple inspection can be performed while maintaining safety, and automation can be easily performed.

[0124] Figure 7 1 is an explanatory diagram schematically showing a state in which the height of the dissimilar metal joint 100 of the joint 27 is measured from the front side and the back side by the height measuring device 21. In the welded portion of the dissimilar metal joint 100, in addition to the front side ( Figure 7 In addition to measuring the height of the weld metal 15 on the upper side ( Figure 7 That is, it is also possible to measure the height of the weld metal 15. Figure 1 The back side excess height 15b of the weld metal 15 shown in the figure is the protruding height h of the second member 13, and is used to determine the soundness of the joint. In this case, a more accurate inspection can be performed. In addition, the soundness of the joint can also be determined based on the measurement data of the height h of the weld metal 15 on the back side. When measuring the height h of the back side of the weld, the height measuring device 21 for measuring the front side can be used for measurement, or a plurality of height measuring devices 21 can be prepared and different measuring devices can be used to measure the front side and the back side.

[0125] Furthermore, the volume of the surface excess 15a as the excess portion of the weld metal 15 on the front side may be measured instead of the height h of the back side of the weld metal 15, and the shape of the back side excess 15b of the weld metal 15 on the back side may be estimated by taking into account the volume, the internal volume of the through hole 11a, and the consumption of the consumable material (welding wire 19). Such estimation based on the volume of the weld metal 15 is particularly useful when the second member 13 is an aluminum extruded material, when the excess on the back side cannot be observed due to structural reasons, when it is desired to inspect in a short time, and when it is desired to reduce the cost of measuring equipment.

[0126] When measuring characteristic quantities such as the height of a plurality of weld metals 15 , a learning model may be generated using machine learning, and the soundness of the welded joint may be determined using the learning model.

[0127] Fig. 8A This is a cross-sectional photograph of a cut surface of a dissimilar metal joint 100 that was determined to be normal. Figure 8B FIG. 1 is a cross-sectional photograph of a cut surface of a dissimilar metal joint 100 judged as defective. Fig. 8A As shown, in the dissimilar metal joint 100, the surface excess 15a having a larger diameter than the through hole 11a of the first member 11 covers the through hole 11a and is formed protrudingly in the plate thickness direction. The back surface excess 15b of this example has a larger diameter than the diameter of the through portion 13a of the second member 13 in the back side surface (the surface on the side opposite to the first member 11 side) of the second member 13 and is formed protrudingly in the plate thickness direction. The back surface excess 15b can be set as required, and its shape can be arbitrary. In addition, the same is true for the surface excess 15a, and its shape is arbitrary and can also be omitted.

[0128] In this case, the surface reinforcement 15a of the weld metal 15 is in close contact with the first member 11 without a gap, thereby improving the bonding strength between the first member 11 and the second member 13. That is, in addition to the bonding strength brought about by welding, the anchoring effect brought about by the surface reinforcement 15a and the back reinforcement 15b sandwiching the first member 11 and the second member 13 is also exerted, and a more solid bonding is obtained for the external stress in the plate thickness direction. In addition, for the shear force in the plate surface direction, a high shear strength is obtained by the shaft portion 15c of the weld metal 15 that penetrates the first member 11 and the second member 13.

[0129] On the other hand, Figure 8B As shown, the weld metal 15 of the dissimilar metal joint 100 hardly protrudes from the surface side of the first member 11, and the weld metal 15 is in a state of falling off from the through hole 11a to the second member 13 side, and the bonding strength between the weld metal 15 and the first member 11 is reduced. In this case, the aforementioned anchoring effect cannot be obtained, and therefore the soundness of the joint is insufficient.

[0130] <Judgment Criteria for Soundness of Dissimilar Metal Joints>

[0131] The judgment device 33 can set judgment criteria for the soundness of the dissimilar metal joint 100 based on various criteria such as the width W of the surface reinforcement 15a of the weld metal 15 that forms the reinforcement portion and the height H from the surface of the first member 11 as shown in the above. Figure 1 is a chart showing the height curve M obtained using the measurement data from the height measuring device 21.

[0132] Fig. 9 The height curve M shown represents the measurement data output from the height measuring device 21 when measuring the shape of the welded portion as a height distribution on one axis (line). As described above, various filtering processes, rejection processes, etc. can also be performed on the measurement data. The height curve M represents the protruding shape of the weld metal 15 from the first member 11. Based on the height curve M, the width W and height H of the reinforcement portion of the weld metal 15 are calculated through operations. The obtained information such as the width W and height H is used for Fig. 9 comparison with the reference in step S3, that is, comparison with the reference width W0 and reference height H0. Figure 6

[0133] Fig.10 Fig. 9 is a chart showing the height curve M and the reference height distribution SF. As described above, the soundness of the joint can be judged by extracting parameters such as the width W and height H of the weld metal 15 from the Fig.10 height curve M shown, but in addition to this, it can also be judged by comparison with the reference height distribution SF. Here, a reference height distribution SF is prepared by setting the reference height according to the position, and the condition that the height curve M is equal to or higher than the height of the reference height distribution SF (M≥SF) is used as the judgment condition. Fig.10 The height curve M shown is higher than the reference height distribution SF at any position and satisfies the judgment condition (M≥SF), so it is judged as "normal".

[0134] Fig.11 is a chart showing the height curve M and the reference height distribution SF. Fig.11 The height of the protruding shape of the welded portion of the height curve M shown is lower than the reference height distribution SF (the region where M < SF). In this case, the judgment condition (M≥SF) is not satisfied, so it is judged as "defective".

[0135] The above-mentioned reference height distribution SF can be set based on pre-set design conditions such as the diameter of the through hole 11a of the dissimilar metal joint 100, the target height, the feeding speed of the welding wire, the welding current, the welding voltage, and the welding time. In addition, the height of a sample product made into an ideal shape can be measured, and the reference height distribution can be set based on the measurement result of the sample product.

[0136] Fig.12 1 is an explanatory diagram showing a height curve M when the through hole 11a of the first member 11 is measured before welding. Fig.13 It is shown based on Fig.12 The center line CL shown in FIG. Fig.12 As shown in FIG. 1 , the center line CL of the through hole 11a (preparatory hole) can be calculated based on the measured height curve M. The reference height can be set within a predetermined range with the position of the center line CL as the center. Fig.13 In this way, the position of the preliminary hole may be measured and recorded before spot welding is performed, and the soundness of the joint may be determined by comparing the height curve M of the weld metal 15 measured after welding with the reference height distribution SF including the pre-recorded position information of the preliminary hole. In this case, even if the position of the preliminary hole is offset, the position of the preliminary hole is actually measured and obtained, and a comparison and determination are performed according to the offset of the preliminary hole, thereby improving the reliability of the determination. Therefore, the influence caused by the position offset will not affect the determination result.

[0137] Fig.14 , Fig.15 The measured height curve M and Fig.13 This is an explanatory diagram of a case where the reference height distribution SF shown is compared. Fig.14 As shown in FIG. 1 , when the height curve M is at a height above the reference height profile SF, it is determined to be “normal”. Fig.15 As shown in FIG. 1 , when at least a portion of the height curve M has a lower height than the reference height distribution SF, it is determined to be "bad". In this way, when the reference height distribution SF is set to deviate from the original position of the center line CL, it is difficult to make an accurate determination. However, as described above, if the center position of the reference height distribution SF is accurately set, a high-precision determination can be stably performed.

[0138] Fig.16 It is an explanatory diagram showing a height curve M when the protruding shape of the welded portion is measured after welding. Fig.17 It is shown based on Fig.15 The illustration of the reference height distribution SF is made based on the position of the center line CL shown in FIG. Fig.16As shown in the figure, the center line CL of the height distribution of the weld metal 15 can be calculated based on the height curve M of the protruding shape of the weld metal 15 from the first member 11. The center line CL can be set with the position of the center line CL as the center. Fig.17 That is, by finding the center position of the protruding shape of the weld metal 15 measured after welding, i.e., the center line CL, and setting the threshold value with the center line CL as the center, it is possible to set the reference height distribution SF based on the position of the actually formed weld metal 15.

[0139] In the above-described determination, the height curve M measured and the reference height distribution SF are determined using the entire curve, but a specific representative point may be used for comparison.

[0140] Fig.18 , Fig.19 1 is an explanatory diagram showing a situation where the positional relationship of representative points extracted from the measured height curve M is compared with a reference. Fig.18 As shown in FIG. 1 , the apex P1 which is the maximum height of the protruding shape and the upwardly rising end points P2 and P3 of both sides of the apex P1 are extracted from the measured height curve M. FIG.

[0141] Here, the height from the vertex P1 of the height curve M to the point P4 intersecting the line connecting the end points P2 and P3 in the vertical direction below the vertex P1 is defined as the protrusion height H. In addition, the minimum height required to protrude vertically upward from the line connecting the end points P2 and P3 is defined as the reference height H. th In addition, the length of the line segment connecting the end points P2 and P3 is defined as the width W of the weld metal protrusion, and the minimum allowable width of the width W is set as the reference width W. th That is, the judgment condition in this case becomes H ≥ H th , W ≥ W th .

[0142] When using height H and width W to evaluate Fig.18 When the height curve M is shown, the protruding height H is greater than the reference height H th Height, width W is greater than the reference width W th long, so H≥H th , W ≥ W th On the other hand, Fig.19 In the height curve M shown, the width W is greater than the reference width W th Long, but the protruding height H is greater than the base height H th Low, does not satisfy H≥H th , W ≥ W th Therefore, it is judged as "bad".

[0143] Furthermore, the determination may be made based on the volume of the weld metal 15. Here, a method for predicting the state (volume, shape) of the back side excess height 15b of the weld portion based on the height curve M of the weld metal 15 measured after welding and the total amount of the welding wire 19 fed during welding is shown. Fig. 20 It is an explanatory diagram showing a height curve M of the weld metal 15 measured after welding and a height curve M0 measured at the through hole 11 a (preparatory hole) as the welding position before welding. Fig.21 This is an explanatory diagram for explaining the volume of the weld metal 15 formed in the through hole 11 a of the first member 11 after welding.

[0144] like Fig. 20 As shown in FIG. 1 , the volume of the portion of the weld metal 15 formed in the through hole 11a and the portion protruding from the first member 11 including the surface excess 15a can be estimated from the measured height curves M and M0. In addition, the weld metal 15 has a volume corresponding to the total amount of the fed welding wire, and the volume of the back excess 15b can be estimated from the relationship between the volumes of the above-mentioned portions.

[0145] Specifically, the volume V of the back reinforcement 15b is b According to the volume V of the welding wire 19 fed w and the volume V of the protruding portion of the weld metal 15 calculated from the height curve M measured after welding. out and the volume V inside the through hole 11a h The relationship is expressed by formula (1).

[0146] V b =V w -V out -V h -C Formula (1)

[0147] Here, C is a constant and is a term for correcting the effects of loss due to spattering etc. generated during welding, and protrusion of weld metal into the inter-plate gap between the first member 11 and the second member 13. The value of the constant C can be set empirically, can be set by machine learning, or can be set to zero.

[0148] In addition, the surface excess 15a of the weld metal 15 formed at the welding position may be determined by using the area of ​​the surface excess 15a in a plan view. Fig. 22It is an explanatory diagram showing a cross-sectional view and a front view of the weld metal 15 that joins the first member 11 and the second member 13. Here, the plate thickness direction is set as the Z direction, and the plate surface direction orthogonal to the Z direction is set as the X direction and the Y direction. The surface excess height 15a of the weld metal 15 is a part that is in close contact with the first member 11 and exerts an anchoring effect, and preferably has a sufficient area when viewed from the front (on the XY plane). Therefore, the area of ​​the surface excess height 15a is measured and obtained, and compared with a preset reference area to evaluate the soundness of the joint.

[0149] Fig.23 , Fig.24 1 is an explanatory diagram showing the outer edge shape of the surface height 15a of the weld metal 15 in the XY plane. The shape of the surface height 15a can also be measured using the height measuring device 21 ( Figure 4 ) is used for measurement, but an image sensor may be used to detect the outer edge shape of the surface excess height 15a based on the image data obtained by shooting, etc., and a plurality of measurement information may be combined for detection.

[0150] like Fig.23 As shown in FIG. 1 , when the area is large in a manner such that the curve Prf indicating the outer edge of the surface excess height 15a of the weld metal 15 measured after welding covers the preset reference height distribution SP, it is determined to be "normal". Fig.24 As shown in FIG. 1 , when the measured curve Prf indicating the outer edge of the surface excess height 15a is smaller than the preset reference height distribution SP, or deviates from the center of the reference height distribution SP so that the reference height distribution SP protrudes from the curve Prf, it is determined to be "bad". As described above, the reference for comparison with the measured curve Prf can be a reference of various types.

[0151] <Repair of defective parts>

[0152] In the above-mentioned inspection of the welded portion, a step of repairing the welded portion determined to be "defective" may be further provided. Fig.25 The flowchart shows the inspection sequence of the repair process of the welded portion including detection of the position of the preliminary hole, welding and height measurement, and defect determination. Fig.25 The inspection sequence shown is based on the premise that Figure 4 The control device 31 shown is configured to operate according to a program including information on a welding sequence for joining the first member 11 and the second member 13. In the program, information on the welding position, which is the position of the through hole 11a (preparatory hole) of the first member 11, and welding conditions such as welding current, welding voltage, and wire feed speed are registered. The control device 31 reads the prepared program, drives the welding robot 23 according to the program, and performs spot welding at the position of the designated preparatory hole.

[0153] In such a welding sequence, the control device 31 drives the welding robot 23 according to the program, and the height meter 21 is arranged at the position of the preparatory hole that becomes the welding position. In addition, the height of the preparatory hole is measured by the height meter 21 to detect the accurate position of the preparatory hole (S11). The control device 31 compares the detected position of the preparatory hole with the position of the preparatory hole registered in the program, and when there is a deviation between the positions, the teaching position of the welding robot 23 is changed in such a way that the welding position becomes the position of the detected preparatory hole (S12). For example, the position information of the preparatory hole registered in the program is corrected, and the corrected position information is output to the welding robot 23 as the target position information.

[0154] In this way, the position of the preparatory hole measured before welding is fed back to the welding system 200, and the point taught as the welding point is corrected in advance, so that the offset during welding is reduced, and a higher quality joint is obtained. The correction of the target position is preferably to correct the central position of the preparatory hole, but the position offset from the center can also be set as the target position according to the plate group, component shape, performance sought, etc. In addition, by measuring the depth of the preparatory hole, the plate gap between the first component 11 and the second component 13 can be estimated. For example, when the depth of the preparatory hole is 1.9 mm in the case of a steel plate with a plate thickness of 1.4 mm, the plate gap can be estimated to be 0.5 mm. The plate gap is fed back to the welding conditions, and the welding conditions such as the welding current value and the arcing time are changed to conditions suitable for the plate gap, so as to obtain a higher quality joint.

[0155] Next, the control device 31 starts the welding action according to the program, positions the welding torch 17 at the position of the corrected preparation hole, and performs spot welding (S13). After welding, the height of the weld metal 15 in the welded portion is measured as described above (S14). The determination device 33 confirms whether the conditions are met (S15) based on the information such as the height curve measured by the height measuring device 21, and determines whether it is "normal" or "bad" (S16, S17). If it is determined to be "normal", the processing is terminated, and if it is determined to be "bad", it is determined whether it can be repaired (S18). If it can be repaired, the welding torch 17 is positioned at the preparation hole and repair welding is performed (S19), and the step S14 of measuring the height of the welded portion is restarted. In the repair welding, selective welding can be performed in a manner to fill the part where the weld metal is insufficient, spot welding can be performed by changing the conditions such as the welding current, welding voltage, and the feeding speed of the welding wire, or spot welding can be performed again without changing the conditions. It is preferred that the repair welding process content is set according to the measured height curve. On the other hand, when repair is difficult, it is determined that another step is necessary to perform inspection ( S20 ), and the processing is terminated.

[0156] In this sequence, the above-mentioned steps S18, S19, and S20 are added as a repair process ST. In this way, the judgment result of the welded part is fed back to the welding system 200, and the repair process ST is implemented in advance when it is judged to be defective, so that the work of repairing the defective part in the subsequent process can be reduced. The specific treatment content of the repair process ST is preferably prepared in advance in multiple ways according to the bad judgment mode. For example, a mode of insufficient excess height, a mode in which the weld metal is greatly offset relative to the prepared hole, etc., can be appropriately handled according to the situation. In addition, when it is judged to be defective, the welding conditions such as welding current and welding voltage at this time, and the measurement data such as displacement are saved to build a database, which can help to find out the cause of the bad judgment.

[0157] As described above, the welding system 200 has a correction function for correcting the spot welding position and a repair function for repairing the welded portion as necessary.

[0158] In the above-mentioned procedure, the inspection is performed each time one point is welded, but the inspection may be performed collectively after welding multiple points.

[0159] Fig.26 It shows that Fig.25 The flowchart of the inspection sequence shown in FIG. 1 is a flowchart of the inspection sequence in which the inspection is changed from each point to a multi-point inspection. In this inspection sequence, first, the detection of the position of the preparation hole (S31) and the change of the teaching position (S32) are repeatedly performed for all the welding points (S33). Then, the welding torch 17 is positioned at the corrected position of the preparation hole, and spot welding is performed (S34). This process is repeated for all the welding points (S35).

[0160] After welding, the height of the weld metal 15 in the weld is measured as described above (S36). Confirm whether the conditions are met (S37) and determine whether it is "normal" or "bad". In the case of being judged as "bad", similar to the aforementioned repair process ST, if it can be repaired, the repair treatment is implemented (S38), and the process is repeated from step S36 of measuring the height of the weld. It should be noted that in the case of difficulty in repair, the measurement of the height of the next weld is carried out (S36). In the case of being judged as "normal", the process from the above-mentioned step S36 is repeated until the inspection of all welds is completed (S39). According to this sequence, multiple welds can be continuously welded, judged, and repaired, and the joint 27 can be manufactured efficiently.

[0161] Thus, the present invention is not limited to the above-mentioned embodiments, and the combination of the structures of the embodiments and the changes and applications made by those skilled in the art based on the description in the specification and known technologies are also intended by the present invention and are included in the scope of the protection requested.

[0162] As described above, the following matters are disclosed in this specification.

[0163] (1) A method for inspecting a dissimilar metal joint, the dissimilar metal joint being formed by spot welding a plate assembly consisting of at least one first member made of steel and having a through hole in the plate thickness direction and a second member made of nonferrous metal overlapping each other at the position of the through hole, wherein:

[0164] measuring a protrusion height of weld metal formed by the spot welding from a surface of the first member on the side opposite to the second member,

[0165] The welding state of the spot welding is determined based on the measured protrusion height.

[0166] According to this dissimilar metal joint inspection method, by measuring the protrusion height of weld metal protruding from the first member formed by spot welding the first member and the second member, the welding state such as the joint strength can be determined based on the protrusion height.

[0167] (2) The method for inspecting a dissimilar metal joint according to (1), wherein:

[0168] measuring a protrusion height of weld metal formed by the spot welding from a back surface of the second member on the side opposite to the first member,

[0169] The welding state of the spot welding is determined based on the measured protrusion height from the front surface and the measured protrusion height from the back surface.

[0170] According to this inspection method of a dissimilar metal joint, by measuring the protrusion height of the weld metal from the second member, the welding state such as the joint strength can be determined more accurately based on the protrusion height.

[0171] (3) The method for inspecting a dissimilar metal joint according to (1) or (2), wherein:

[0172] The welding state of the spot welding is determined using the protrusion heights of the weld metal at three or more points.

[0173] According to this inspection method of a dissimilar metal joint, the maximum height and width of the protrusion can be obtained from the protrusion heights at three or more points, and the determination process can be simplified.

[0174] (4) The method for inspecting a dissimilar metal joint according to any one of (1) to (3), wherein:

[0175] The protrusion height of the weld metal is measured using a laser displacement meter.

[0176] According to this inspection method of a dissimilar metal joint, it is possible to perform an immediate inspection without contact with the measurement object by irradiating laser light.

[0177] (5) The method for inspecting a dissimilar metal joint according to any one of (1) to (3), wherein:

[0178] The protrusion height of the weld metal is measured based on a captured image detected by an image sensor.

[0179] According to this inspection method of a dissimilar metal joint, height information is extracted from information of a captured image, so that an immediate inspection can be performed without contact with the measurement object.

[0180] (6) The method for inspecting a dissimilar metal joint according to any one of (1) to (5), wherein:

[0181] The second member is made of aluminum or an aluminum alloy, or magnesium or a magnesium alloy.

[0182] According to this inspection method of a dissimilar metal joint, the strength of a joint formed by joining a steel material to a light metal such as aluminum or magnesium can be determined with high accuracy.

[0183] (7) The method for inspecting a dissimilar metal joint according to any one of (1) to (6), wherein:

[0184] Before performing the spot welding, the position of the through hole is measured.

[0185] The welding state is determined based on the protrusion height of the weld metal corresponding to the measured position of the through hole.

[0186] According to this inspection method of a dissimilar metal joint, by measuring the protruding height of the weld metal corresponding to the position of the through hole, the measurement position can be accurately determined, and the measurement accuracy can be improved.

[0187] (8) The method for inspecting a dissimilar metal joint according to (7), wherein:

[0188] The position of the through hole is measured using a height gauge that measures the protruding height of the weld metal.

[0189] According to this inspection method of a dissimilar metal joint, the position of the through hole is measured using a height gauge for measuring the protrusion height. Therefore, the position of the through hole can be measured by adding a simple process, and the cost of the device is also suppressed.

[0190] (9) A welding method, wherein:

[0191] The welding method has the following characteristics:

[0192] A welding step of spot welding a plate assembly formed by overlapping at least one first member made of steel and having a through hole in the plate thickness direction and a second member made of nonferrous metal at positions of the through hole to form a dissimilar metal joint;

[0193] a measuring step of measuring at least one of a protrusion height of the weld metal formed by the spot welding from the surface of the first member on the side opposite to the second member and a protrusion height of the weld metal formed by the spot welding from the back surface of the second member on the side opposite to the first member;

[0194] a determination step of determining a welding state of the spot welding based on the measured protrusion height; and

[0195] The repairing step is to repair the welding position of the spot welding when the welding state of the spot welding is determined to be defective.

[0196] According to the welding method, for a dissimilar metal joint formed by spot welding a first member and a second member in a welding process, at least one of the protrusion heights of the weld metal from the first member or the second member is measured in a measuring process. The welding state of the spot welding is determined in a determination process based on the measured protrusion height. When the welding state is determined to be poor, the welding position is repaired in a repair process. In this way, by feeding back the determination result of the welding state and repairing the part determined to be poor in advance, the work of repairing the poor part in the subsequent process can be reduced.

[0197] (10) The welding method according to (9), wherein:

[0198] Before the spot welding, there is a step of measuring the position of the through hole.

[0199] In the welding process, the measured position of the through hole is feedback-controlled as a target position of the spot welding, and the next spot welding position is corrected.

[0200] According to this welding method, spot welding can be performed at an accurate position where positional deviation has been corrected, so that desired joint strength can be easily obtained.

[0201] (11) An inspection device for a dissimilar metal joint, the dissimilar metal joint being formed by spot welding a plate assembly consisting of at least one first member made of steel having a through hole in the plate thickness direction and a second member made of nonferrous metal overlapping each other at the position of the through hole, wherein:

[0202] The inspection device for dissimilar metal joints comprises:

[0203] a height measuring unit that measures a protrusion height of weld metal formed by the spot welding from a surface of the first member on the side opposite to the second member; and

[0204] A determination unit determines a welding state of the spot welding based on the measured height.

[0205] According to the inspection device for dissimilar metal joints, the height measuring unit measures the protrusion height of weld metal protruding from the first member formed by spot welding the first member and the second member, so that the determination unit can determine the welding state such as joint strength based on the protrusion height.

[0206] (12) The inspection device for a dissimilar metal joint according to (11), wherein:

[0207] The height measuring unit measures a protrusion height of the weld metal formed by the spot welding from the back surface of the second member on the side opposite to the first member side.

[0208] The determination unit determines a welding state of the spot welding based on a measured protrusion height from the front surface of the first member and a measured protrusion height from the back surface of the second member.

[0209] According to this inspection method of a dissimilar metal joint, by measuring the protrusion height of the weld metal from the second member, the welding state such as the joint strength can be determined more accurately based on the protrusion height.

[0210] (13) A welding system, wherein:

[0211] The welding system has:

[0212] The inspection device for dissimilar metal joints according to (11) or (12); and

[0213] a welding device for joining the first member and the second member by the spot welding to form the dissimilar metal joint,

[0214] The welding system has a repair function of driving the welding device to repair the welded position of the spot welding determined to be defective when the welding state of the spot welding is determined to be defective.

[0215] According to the welding system, for a dissimilar metal joint formed by spot welding a first member and a second member using a welding device, at least one of the protrusion heights of the weld metal protruding from the first member or the second member is measured by an inspection device. The welding state of the spot welding is determined in a determination process based on the measured protrusion height. When the welding state is determined to be poor, the welding position is repaired by a repair device. In this way, by feeding back the determination result of the welding state and repairing the part determined to be poor in advance, the work of repairing the poor part in the subsequent process can be reduced.

[0216] (14) The welding system according to (13), wherein:

[0217] The welding system has a correction function of measuring the position of the through hole before spot welding and performing feedback control of the measured position of the through hole as a target position of spot welding to correct the spot welding position.

[0218] According to this welding system, spot welding can be performed at an accurate position where positional deviation has been corrected, and therefore desired joint strength can be easily obtained.

[0219] (15) The welding system according to (13) or (14), wherein:

[0220] The welding device includes a welding robot for performing the spot welding.

[0221] The height measuring unit is provided on a movable part of the welding robot.

[0222] According to the welding system, the installation space and equipment investment cost can be reduced. In addition, by driving the welding robot, the height measuring unit can be easily arranged at a desired measuring position, so that it is easy to perform an immediate inspection after welding. In addition, the production cycle time can be shortened.

Claims

1. A method for inspecting a dissimilar metal joint, wherein the dissimilar metal joint is formed by spot welding a plate assembly formed by overlapping at least one first member made of steel and having a through hole in the plate thickness direction and a second member made of nonferrous metal at the position of the through hole, wherein: measuring a protrusion height of weld metal formed by the spot welding from a surface of the first member on the side opposite to the second member, The welding state of the spot welding is determined based on the measured protrusion height.

2. The method for inspecting a dissimilar metal joint according to claim 1, wherein: measuring a protrusion height of weld metal formed by the spot welding from a back surface of the second member on the side opposite to the first member, The welding state of the spot welding is determined based on the measured protrusion height from the front surface and the measured protrusion height from the back surface.

3. The method for inspecting a dissimilar metal joint according to claim 1, wherein: The welding state of the spot welding is determined using the protrusion heights of the weld metal at three or more points.

4. The method for inspecting a dissimilar metal joint according to claim 1, wherein: The protrusion height of the weld metal is measured using a laser displacement meter.

5. The method for inspecting a dissimilar metal joint according to claim 1, wherein: The protrusion height of the weld metal is measured based on a captured image detected by an image sensor.

6. The method for inspecting a dissimilar metal joint according to claim 1, wherein: The second member is made of aluminum or an aluminum alloy, or magnesium or a magnesium alloy.

7. The method for inspecting a dissimilar metal joint according to claim 1, wherein: Before performing the spot welding, the position of the through hole is measured. The welding state is determined based on the protrusion height of the weld metal corresponding to the measured position of the through hole.

8. The method for inspecting a dissimilar metal joint according to claim 7, wherein: The position of the through hole is measured using a height gauge that measures the protruding height of the weld metal.

9. A welding method, wherein: The welding method has the following characteristics: A welding step of spot welding a plate assembly formed by overlapping at least one first member made of steel and having a through hole in the plate thickness direction and a second member made of nonferrous metal at the position of the through hole to form a dissimilar metal joint; a measuring step of measuring at least one of a protrusion height of the weld metal formed by the spot welding from the surface of the first member on the side opposite to the second member and a protrusion height of the weld metal formed by the spot welding from the back surface of the second member on the side opposite to the first member; a determination step of determining a welding state of the spot welding according to the measured protrusion height; as well as The repairing step is to repair the welding position of the spot welding when the welding state of the spot welding is determined to be defective.

10. The welding method according to claim 9, wherein: Before the spot welding, there is a step of measuring the position of the through hole. In the welding process, the measured position of the through hole is feedback-controlled as a target position of the spot welding, and the next spot welding position is corrected.

11. An inspection device for a dissimilar metal joint, the dissimilar metal joint being formed by spot welding a plate assembly consisting of at least one first member made of steel and having a through hole in the plate thickness direction and a second member made of nonferrous metal overlapping each other at the position of the through hole, wherein: The inspection device for dissimilar metal joints comprises: a height measuring unit for measuring a protrusion height of weld metal formed by the spot welding from a surface of the first member on the side opposite to the second member; as well as A determination unit determines a welding state of the spot welding based on the measured height.

12. The inspection device for dissimilar metal joints according to claim 11, wherein: The height measuring unit measures a protrusion height of the weld metal formed by the spot welding from the back surface of the second member on the side opposite to the first member side. The determination unit determines a welding state of the spot welding based on a measured protrusion height from the front surface of the first member and a measured protrusion height from the back surface of the second member.

13. A welding system, wherein: The welding system has: The inspection device for dissimilar metal joints according to claim 11 or 12; and a welding device for joining the first member and the second member by the spot welding to form the dissimilar metal joint, The welding system has a repair function of driving the welding device to repair the welded position of the spot welding determined to be defective when the welding state of the spot welding is determined to be defective.

14. The welding system according to claim 13, wherein: The welding system has a correction function of measuring the position of the through hole before spot welding and performing feedback control of the measured position of the through hole as a target position of spot welding to correct the spot welding position.

15. The welding system according to claim 13, wherein: The welding device includes a welding robot for performing the spot welding. The height measuring unit is provided on a movable part of the welding robot.

Images