Laser welding equipment

Abstract

To provide a laser welding apparatus comprising a heating device which is configured to suppress a welding laser irradiation unit from restricting a configuration of the heating device.SOLUTION: The laser welding apparatus, which welds a welding target including two or more members, comprises: a welding laser irradiation unit that faces the welding target and irradiates a laser beam to a welding target portion of the welding target so as to weld the welding target; and a heating device that is arranged on an opposite side to the welding laser irradiation unit with respect to the welding target, and heats the welding target portion from an opposite side to pre-heat the welding target portion.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This disclosure relates to a laser welding apparatus.

Background Art

[0002] In laser welding, a technique for suppressing cracking of a welding object by preheating a welding portion of the welding object with a preheating device is known. For example, Patent Document 1 discloses a laser welding apparatus having a laser irradiation unit for welding and a preheating device for irradiating a light beam. In this laser welding apparatus, the laser irradiation unit and the preheating device are each disposed above the welding object.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When both the laser irradiation unit and the preheating device are disposed above the welding object as in Patent Document 1, for example, the size, installation angle, and distance from the welding object of the preheating device need to be set so that the preheating device does not contact the laser irradiation unit and the preheating device does not block the laser. Therefore, in Patent Document 1, the configuration of the preheating device may be restricted by the laser irradiation unit.

Means for Solving the Problems

[0005] The present invention can be realized in the following forms. According to one embodiment of the present disclosure, a laser welding apparatus is provided for welding a workpiece comprising two or more members. The laser welding apparatus comprises a welding laser irradiation unit that faces the workpiece and welds the workpiece by irradiating the workpiece with laser light; and a heating device that is positioned on the opposite side of the workpiece from the welding laser irradiation unit and preheats the workpiece by heating the workpiece from the opposite side. The heating device is composed of a lamp that heats the workpiece by irradiating it with infrared rays. The irradiation unit of the lamp is positioned to face the workpiece. The laser welding apparatus further comprises a cover member positioned between the workpiece and the irradiation unit, covering a part of the irradiation unit and configured to reduce the laser light irradiated onto the irradiation unit. The cover member has higher heat resistance than the workpiece and the irradiation unit.

[0006] (1) According to one embodiment of the present disclosure, a laser welding apparatus is provided for welding a workpiece including two or more members. The laser welding apparatus comprises a welding laser irradiation unit that faces the workpiece and irradiates the workpiece to be welded with laser light to weld the workpiece, thereby welding the workpiece, and a heating device that is positioned on the opposite side of the workpiece from the welding laser irradiation unit and preheats the workpiece to be welded by heating the workpiece to be welded from the opposite side. In this configuration, the heating device is positioned on the opposite side of the welding laser irradiation unit from the workpiece to be welded. By heating the workpiece from the opposite side of the welding laser irradiation unit using this heating device, the workpiece can be preheated. Therefore, compared to the case where the heating device is positioned on the same side as the welding laser irradiation unit, the configuration of the heating device is less restricted by the welding laser irradiation unit. (2) In the above embodiment, the object to be welded has a first plate-shaped member and a second plate-shaped member as the members, and the first plate-shaped member and the second plate-shaped member may be stacked on top of each other. (3) In the above embodiment, the object to be welded has a first plate-shaped member and a second plate-shaped member as the members, the first plate-shaped member and the second plate-shaped member are arranged side by side in the planar direction, and the welding laser irradiation unit may weld between the first plate-shaped member and the second plate-shaped member. (4) In the above configuration, the welding laser irradiation unit is configured to weld the object to be weld while moving the irradiation position of the laser beam on the object to be welded along a predetermined movement path, and the portion to be welded has a starting end that is welded at the starting point of the movement path and a terminal end that is welded at the end point of the movement path, and the heating device may preheat the terminal end by heating the terminal end. In this configuration, the terminal end can be preheated by the heating device, so cracking of the object to be welded can be effectively suppressed. (5) In the above configuration, the object to be welded is plate-shaped, the welding laser irradiation unit irradiates the laser beam toward the plate surface of the object to be welded, and the heating device may be positioned so as to overlap at least a portion of the end portion when viewed in the plate thickness direction of the object to be welded. With this configuration, for example, compared to a configuration in which the heating device does not overlap the end portion when viewed in the plate thickness direction, the end portion can be preheated with the heating device positioned closer to the end portion. Therefore, the end portion can be preheated more effectively by the heating device, and cracking of the object to be welded can be suppressed more effectively. (6) In the above embodiment, the heating device is composed of a lamp that heats the area to be welded by irradiating the object to be welded with infrared rays, the irradiation part of the lamp is positioned to face the object to be welded, and further comprises a cover member positioned between the object to be welded and the irradiation part, covering a part of the irradiation part, the cover member may have higher heat resistance than the object to be welded and the irradiation part. With this embodiment, the irradiation part of the lamp can be protected from laser light by the cover member. Also, compared to an embodiment in which the entire irradiation part is covered by the cover member, for example, the area to be welded can be heated more effectively by the infrared rays irradiated from the irradiation part.

[0007] This disclosure can be implemented in various forms other than the laser welding apparatus described above, such as a laser welding method or a control method for a laser welding apparatus. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows the schematic configuration of the laser welding apparatus in the first embodiment. [Figure 2] This is a diagram illustrating the welding target area in the first embodiment. [Figure 3] This figure shows the schematic configuration of the laser welding apparatus in the second embodiment. [Figure 4] This is a diagram illustrating the position of the cover component. [Figure 5] This is a diagram illustrating the welding target area in the third embodiment. [Figure 6] This figure shows the object to be welded in the fourth embodiment. [Figure 7] This is a diagram illustrating the welding target area in the fourth embodiment. [Figure 8] This is the first figure illustrating the welding target area in the fifth embodiment. [Figure 9] This is a second figure illustrating the welding target area in the fifth embodiment. [Modes for carrying out the invention]

[0009] A. First Embodiment: Figure 1 shows a schematic configuration of the laser welding apparatus 10. Figure 1 shows arrows aligned in the mutually orthogonal X, Y, and Z directions. The X, Y, and Z directions are aligned with the three mutually orthogonal spatial axes, the X, Y, and Z axes, and include both the direction along one side of the X, Y, and Z axes, and the opposite direction. The X and Y axes are axes aligned with the horizontal plane, while the Z axis is an axis aligned with the vertical line. Hereafter, the +Z direction will also be referred to as "up," and the -Z direction as "down."

[0010] The laser welding apparatus 10 welds the workpiece OW by irradiating it with laser light LB. The laser welding apparatus 10 comprises a laser oscillator 11, an optical path 15, a welding laser irradiation unit 20, a stage 30, a heating device 50, and a control unit 90.

[0011] The control unit 90 is configured as a computer comprising a CPU 91, a storage unit 92, and an input / output interface. The CPU 91 executes programs stored in the storage unit 92, thereby enabling the control unit 90 to implement various functions, including functions for preheating the workpiece OW and welding the workpiece OW. In other embodiments, the control unit 90 may be configured as, for example, a PLC (Programmable Logic Controller). Furthermore, the functions of the control unit 90 may be implemented by circuits.

[0012] Stage 30 supports the workpiece OW to be welded. The workpiece OW includes two or more members. The workpiece OW may constitute, for example, the entirety of a member or product, or it may constitute a part of a member or product. In this embodiment, the workpiece OW has a plate shape. The workpiece OW also has a first plate-shaped member MP1 and a second plate-shaped member MP2 as members constituting the workpiece OW. The first plate-shaped member MP1 and the second plate-shaped member MP2 are each rectangular aluminum plates. The first plate-shaped member MP1 and the second plate-shaped member MP2 are stacked on top of each other in the thickness direction of the workpiece OW. In this embodiment, the thickness direction is the Z direction. The second plate-shaped member MP2 is placed directly on top of Stage 30. The first plate-shaped member MP1 is placed directly on top of the second plate-shaped member MP2. Preferably, the gap between the lower surface of the first plate-shaped member MP1 and the upper surface of the second plate-shaped member MP2 is small enough to suppress welding defects caused by this gap. For example, in order to improve the degree of contact between the first plate-shaped member MP1 and the second plate-shaped member MP2, a jig (not shown) for pressing the first plate-shaped member MP1 against the second plate-shaped member MP2 may be appropriately installed on the stage 30.

[0013] Furthermore, the phrase "the first plate-shaped member MP1 and the second plate-shaped member MP2 are laminated" means not only that the first plate-shaped member MP1 and the second plate-shaped member MP2 are laminated in the thickness direction so that they completely overlap each other, but also that the first plate-shaped member MP1 and the second plate-shaped member MP2 are laminated in the thickness direction so that a part of the first plate-shaped member MP1 and a part of the second plate-shaped member MP2 overlap each other. When the first plate-shaped member MP1 and the second plate-shaped member MP2 are laminated as in this embodiment, the overlapping portions of the two are welded together.

[0014] The laser oscillator 11 emits laser light LB. The type of laser light LB emitted can be any type, such as a CO2 laser, YAG laser, fiber laser, disk laser, or excimer laser. The laser light LB emitted by the laser oscillator 11 is transmitted to the welding laser irradiation unit 20 via the optical path 15. The optical path 15 includes, for example, an optical fiber cable or mirrors for transmitting the laser light LB.

[0015] The welding laser irradiation unit 20 condenses the laser beam LB transmitted from the laser oscillator 11 and irradiates it toward the welding object OW. The welding laser irradiation unit 20 is disposed to face the welding object OW. The welding laser irradiation unit 20 welds the welding object OW by irradiating the laser beam LB onto the welding target site WP of the welding object OW. In the present embodiment, the welding laser irradiation unit 20 is disposed above the welding object OW so as to face the upper surface of the welding object OW, and irradiates the laser beam LB from above the welding object OW toward the plate surface (upper surface) of the welding object OW. In the present embodiment, the irradiation direction of the laser beam LB onto the welding object OW is the -Z direction. That is, the optical axis AX of the laser beam LB irradiated from the welding laser irradiation unit 20 is along the Z direction and is orthogonal to the surface direction of the welding object OW. In other embodiments, the optical axis AX may not be orthogonal to the surface direction of the welding object OW, that is, may be inclined with respect to the Z direction.

[0016] The welding laser irradiation unit 20 in the present embodiment is configured as a head having a galvanometer scanner. The welding laser irradiation unit 20 is configured to be able to arbitrarily control the focal position and the irradiation position of the laser beam LB irradiated onto the welding object OW by changing the angle of the galvanometer mirror mounted on the galvanometer scanner under the control of the control unit 90. In the present embodiment, the focal position is the position in the Z direction, and the irradiation position is the positions in the X and Y directions. Further, the welding laser irradiation unit 20 is configured to be movable with respect to the stage 30. More specifically, the welding laser irradiation unit 20 is fixed to a robot arm (not shown) and is moved by the operation of the robot arm under the control of the control unit 90. This robot is configured, for example, as a 3-axis robot or a 6-axis robot. When the robot is configured as a 6-axis robot, the angle of the welding laser irradiation unit 20 with respect to the stage 30 can also be controlled. In other embodiments, the movement of the welding laser irradiation unit 20 may be realized, for example, by a horizontal movement mechanism or a lifting mechanism configured as an electric actuator.

[0017] In Figure 1, the weld area WP of the workpiece OW is marked with a dotted hatching pattern. The weld area WP is the part of the workpiece OW that is to be welded. More specifically, the weld area WP is the part that is heated above its melting point when irradiated with laser light LB during welding, and is the part where a weld mark is formed by welding. More precisely, the weld area WP includes the part that is directly irradiated with laser light LB and the surrounding part that melts due to the heat from the laser light LB. Each component constituting the workpiece OW is joined to each other by welding the weld area WP. In this embodiment, the weld area WP does not penetrate the workpiece OW in the direction of irradiation of the laser light LB. This type of welding, which does not penetrate the workpiece OW, is sometimes called non-penetrating welding. A type of welding that penetrates the workpiece OW is sometimes called penetrating welding.

[0018] The shape of the weld point (WP) can be predicted before welding of the weld object (OW) actually begins, provided that the welding conditions and the weld object (OW) are predetermined. The shape of the weld point (WP) may be predicted, for example, based on the results of welding a similar object to the weld object (OW) under similar conditions beforehand, or based on the results of a welding simulation of the weld object (OW).

[0019] Figure 2 illustrates the welding target area WP in this embodiment. In this embodiment, the welding laser irradiation unit 20 is configured to weld the workpiece OW while moving the irradiation position IP of the laser beam LB on the workpiece OW. Such movement of the irradiation position IP is achieved, for example, by changing the angle of the galvanometer mirror or by moving or changing the angle of the welding laser irradiation unit 20 using a robot arm.

[0020] When the workpiece OW is welded while the irradiation position IP is moved, the welded area WP has a starting point SE and an ending point EE. The starting point SE is the rear end of the welded area WP in the direction of movement of the irradiation position IP, and corresponds to the starting point SP of the movement path RT of the irradiation position IP. The starting point SE is welded at the starting point SP of the movement path RT, that is, at the beginning of welding the welded area WP. The ending point EE is the front end of the welded area WP in the direction of movement of the irradiation position IP, and corresponds to the ending point EP of the movement path RT. The ending point EE is welded at the ending point EP of the movement path RT, that is, at the end of welding the welded area WP.

[0021] In this embodiment, the control unit 90 moves the welding laser irradiation unit 20 during welding so that the irradiation position IP moves linearly in the +X direction from the starting point SP to the ending point EP. Therefore, as shown in Figure 2, the movement path RT and the welding target area WP in this embodiment extend linearly along the X direction when viewed along the Z direction. The end portion EE is located at a position in the +X direction of the starting point SE. More specifically, the welding target area WP in this embodiment extends from the -X direction end of the welding target object OW to a position before the +X direction end. Therefore, the starting point SE is located at the -X direction end of the welding target object OW, and the end portion EE is located in the X direction between the starting point SE and the +X direction end of the welding target object OW.

[0022] As shown in Figure 1, the heating device 50 is positioned on the opposite side of the welding laser irradiation unit 20 from the workpiece OW to be welded. In this embodiment, the heating device 50 is positioned below the workpiece OW to be welded. The heating device 50 heats the workpiece OW to be welded from the opposite side of the welding laser irradiation unit 20, that is, from below. The heating device 50 may be configured to be movable relative to the stage 30 under the control of the control unit 90, for example, by an electric actuator or a robot.

[0023] In this embodiment, the heating device 50 consists of a lamp 51 that heats the welding target area WP by irradiating the workpiece OW with infrared rays. In this embodiment, the lamp 51 is configured as a halogen lamp. The irradiation part 52 of the lamp 51 is made of quartz glass. The heating device 50 is positioned in an opening 31 provided in the stage 30 such that the irradiation part 52 faces upward. The opening 31 opens upward towards the stage 30. Therefore, the irradiation part 52 faces the portion of the lower surface of the workpiece OW placed on the stage 30 that covers the opening 31.

[0024] Let's return to the explanation of Figure 2. In this embodiment, the heating device 50 is positioned so as to overlap at least a portion of the end portion EE when viewed along the Z direction. More specifically, the heating device 50 is positioned so that, when viewed along the Z direction, the central portion of the irradiation part 52 of the lamp 51 in the X and Y directions is located directly below the end portion EE. In Figure 2, the area where the heating device 50 is positioned when viewed along the Z direction is hatched upwards to the right. In this embodiment, the heating device 50 heats the end portion EE while overlapping at least a portion of it. In this embodiment, the dimensions of the workpiece OW in the X and Y directions are larger than the dimensions of the heating device 50 in the X and Y directions. Therefore, as shown in Figure 2, the workpiece OW has a region R1 that does not overlap with the heating device 50 heating the end portion EE when viewed along the Z direction. This region R1 is the region that does not overlap with the end portion EE when viewed along the Z direction.

[0025] The control unit 90 performs preheating of the workpiece OW by controlling the heating device 50. Preheating of the workpiece OW refers to heating a certain part of the workpiece OW with the heating device 50 prior to irradiating that part with laser light LB. During preheating, the welding area WP is heated to a temperature lower than the melting point of the workpiece OW. Preferably, the heating temperature during preheating is high enough to suppress the occurrence of hot cracks in the welding area WP during welding. The heating temperature during preheating may be set taking into account the timing of preheating completion and the timing of laser light LB irradiation. For example, if the time between the completion of preheating of a certain area and the irradiation of that area with laser light LB is shorter, welding is more likely to start with the temperature of the preheated area maintained at a higher level compared to when this time is longer. Therefore, in this case, the heating temperature may be set lower. In this way, for example, the time required to raise the temperature of the workpiece OW and the energy consumed can be reduced. Furthermore, the control unit 90 may preheat a certain part and then irradiate that part with laser light LB while stopping the heating of that part, or it may irradiate that part with laser light LB while continuing to heat that part.

[0026] In the laser welding apparatus 10 of this embodiment described above, the heating device 50 is positioned on the opposite side of the welding laser irradiation unit 20 from the workpiece OW to be welded, and preheats the workpiece WP to be welded by heating it from the opposite side of the welding laser irradiation unit 20. With this configuration, the configuration of the heating device 50 can be suppressed from being limited by the welding laser irradiation unit 20, compared to the case where the heating device 50 is positioned on the same side as the welding laser irradiation unit 20.

[0027] Furthermore, in this embodiment, the heating device 50 preheats the end portion EE by heating the end portion EE. It is generally known that high-temperature cracking is more likely to occur in the end portion EE compared to other parts of the welding target area WP. By preheating this end portion EE, cracking of the welding target OW can be effectively suppressed.

[0028] Furthermore, in this embodiment, the heating device 50 is positioned so as to overlap with at least a portion of the end portion EE of the welding target area WP when viewed in the plate thickness direction. With this configuration, for example, compared to a configuration in which the heating device 50 does not overlap with the end portion EE when viewed in the plate thickness direction, the end portion EE can be heated with the heating device 50 positioned closer to the end portion EE. Therefore, the end portion EE can be heated efficiently by the heating device 50, and cracking of the welding target OW can be suppressed more effectively.

[0029] Furthermore, in this embodiment, the workpiece OW to be welded has a region R1 that does not overlap with the heating device 50 that preheats the end portion EE when viewed along the Z direction. Therefore, the influence of the heat from the heating device 50 on region R1 can be suppressed.

[0030] B. Second Embodiment: Figure 3 shows a schematic configuration of the laser welding apparatus 10b in the second embodiment. In the second embodiment, unlike the first embodiment, the laser welding apparatus 10b is equipped with a cover member 60. The configuration of the laser welding apparatus 10b in the second embodiment is the same as in the first embodiment, except for parts that are not specifically described.

[0031] In Figure 3, as in Figure 1, the welding target area WPb is marked with a dotted hatching pattern. In this embodiment, the laser welding apparatus 10b performs through welding. That is, in this embodiment, the welding target area WPb penetrates the welding target object OW in the direction of irradiation of the laser beam LB. Therefore, when the laser beam LB penetrates the welding target object OW, it can also irradiate the stage 30 and the opening 31.

[0032] As shown in Figure 3, the cover member 60 described above is positioned between the workpiece OW to be welded and the irradiation section 52 of the lamp 51.

[0033] Figure 4 illustrates the position of the cover member 60. In Figure 4, the position where the cover member 60 is installed is indicated by a downward-sloping hatch. The cover member 60 covers a portion of the irradiation unit 52. More specifically, as shown in Figure 4, the cover member 60 overlaps a portion of the irradiation unit 52 when viewed in the Z direction along the optical axis AX. In this embodiment, the cover member 60 covers a portion of the irradiation unit 52 from above so that the laser beam LB that has reached the opening 31 does not directly irradiate the irradiation unit 52. More specifically, the cover member 60 is positioned in the portion of the irradiation unit 52 that overlaps with the movement path RT when viewed along the optical axis AX. The dimensions of the cover member 60 in the X and Y directions are set to be large enough that the laser beam LB does not directly irradiate the irradiation unit 52, based on the beam diameter of the laser beam LB and the distance between the cover member 60 and the welding laser irradiation unit 20.

[0034] Furthermore, in this embodiment, the cover member 60 is positioned so as not to overlap with the entire end portion EE when viewed along the Z direction. For example, as shown in Figure 4, the cover member 60 does not overlap with the tip tp of the end portion EE when viewed in the Z direction.

[0035] The cover member 60 has higher heat resistance than the workpiece OW and the irradiation unit 52. In determining heat resistance, for materials that undergo glass transition, the higher the glass transition point of the material, the higher the heat resistance. For materials that do not undergo glass transition, the higher the melting point of the material, the higher the heat resistance. In this embodiment, when the workpiece OW is made of aluminum and the irradiation unit 52 is made of quartz glass, the cover member 60 is formed from various metals such as steel and stainless steel, or various ceramics such as alumina and silicon nitride. Furthermore, for example, by increasing the absorption rate of the laser light LB of the cover member 60, the intensity of the laser light LB irradiated onto the lamp 51 via the cover member 60 can be reduced, and the thermal effect on the lamp 51 can be suppressed. In this case, for example, depending on the material of the lamp 51 and the wavelength of the laser light LB, the cover member 60 may be formed from a material with an absorption rate high enough to suppress deformation of the lamp 51 due to heat originating from the laser light LB.

[0036] The laser welding apparatus 10b in the second embodiment described above includes a cover member 60 positioned between the workpiece OW and the irradiation section 52 of the lamp 51, which overlaps a portion of the irradiation section 52 when viewed along the irradiation direction of the laser beam LB. The cover member 60 has higher heat resistance than the workpiece OW and the irradiation section 52. Therefore, the irradiation section 52 can be protected from the laser beam LB by the cover member 60. Furthermore, compared to a configuration in which the cover member 60 overlaps the entire irradiation section 52 when viewed along the irradiation direction of the laser beam LB, for example, the welding area WP can be effectively heated by the infrared radiation emitted from the lamp 51.

[0037] As described in the first embodiment, the laser welding apparatus 10 does not necessarily have to be provided with a cover member 60. In a configuration without a cover member 60, if the heating device 50 can be irradiated with laser light LB during welding, it is preferable that the heating device 50 is configured such that deformation of the heating device 50 due to heat originating from the laser light LB is suppressed. In this case, for example, the irradiation section 52 may be formed of a material having higher heat resistance than the workpiece OW to be welded. Also, for example, the thermal influence of the laser light LB on the heating device 50 may be further reduced by positioning the heating device 50 lower than the workpiece OW to be welded.

[0038] C. Third Embodiment: Figure 5 is a diagram illustrating the welding target area WPc in the third embodiment. Unlike the first embodiment, the welding target area WPc is circular rather than linear when viewed along the Z direction. The configuration of the laser welding apparatus 10 in the third embodiment is the same as in the first embodiment, except for parts that are not specifically described.

[0039] In this embodiment, the control unit 90 moves the welding laser irradiation unit 20 so that the irradiation position IP moves circumferentially during welding. In other words, the movement path RT in this embodiment is circumferential. In this embodiment, as the irradiation position IP moves circumferentially during welding, a weld mark is formed along the circumferential direction of the welding target area WPc when viewed along the Z direction. After welding is completed, a circular weld mark remains on the welding target object OW when viewed along the Z direction. The movement path RT may be, for example, a path that moves the irradiation position IP circumferentially over a distance longer than one full rotation of the circumference. Furthermore, the welding method in this embodiment may be through welding or non-through welding.

[0040] In Figure 5, similar to Figure 2, the area where the heating device 50 is positioned when viewed in the Z direction is marked with upward-sloping hatching. Even when welding the workpiece OW while moving the irradiation position IP circumferentially, as in this embodiment, cracking at the end portion EE of the welding target area WPc can be effectively suppressed by heating the end portion EE with the heating device 50, similar to the first embodiment. Figure 5 shows the heating device 50 positioned overlapping the end portion EE when viewed along the Z direction, similar to Figure 2. Note that in Figure 5, the starting end portion SE is omitted for illustrative purposes.

[0041] Furthermore, as shown in Figure 5, if the object to be welded OW has multiple weld target areas WPc, for example, multiple heating devices 50 may be arranged corresponding to each weld target area WPc. Alternatively, for example, an electric actuator may be provided to move the heating device 50 in the X or Y direction, and this electric actuator may be controlled by the control unit 90 to move the heating device 50 to a position corresponding to the end portion EE of the weld target area WPc to be preheated. In Figure 5, three weld target areas WPc are shown, but the number of weld target areas WPc may be two, four or more, or the number of weld target areas WPc may be one, as in the first embodiment.

[0042] The laser welding apparatus 10 in the third embodiment described above also suppresses limitations on the configuration of the heating device 50 due to the welding laser irradiation unit 20.

[0043] In addition, the laser welding apparatus 10 of the third embodiment may be provided with a cover member 60, for example, in the same manner as in the second embodiment.

[0044] D. Fourth Embodiment: Figure 6 shows the weldable object OWb in the fourth embodiment. Unlike the first embodiment, in this embodiment, the first plate-shaped member MP1b is arranged alongside the second plate-shaped member MP2b in the planar direction of the weldable object OWb. In Figure 6, as in Figure 1, a dotted hatching pattern is applied to the weldable area WPd. The configuration of the laser welding apparatus 10 in the fourth embodiment is the same as in the first embodiment unless otherwise described.

[0045] As shown in Figure 6, the first plate-shaped member MP1b is positioned in the -X direction relative to the second plate-shaped member MP2b. The gap between the side surface of the first plate-shaped member MP1b in the +X direction and the side surface of the second plate-shaped member MP2b in the -X direction is preferably small enough to suppress welding defects caused by this gap. In this embodiment as well, a jig for pressing the first plate-shaped member MP1b against the second plate-shaped member MP2b may be provided, similar to that described in the first embodiment.

[0046] Figure 7 illustrates the welding target area WPd in ​​the third embodiment. In this embodiment, the welding target area WPd extends along the Y direction between the first plate-shaped member MP1b and the second plate-shaped member MP2b. In other words, in this embodiment, the welding laser irradiation unit 20 welds between the first plate-shaped member MP1b and the second plate-shaped member MP2b. More specifically, in this embodiment, the control unit 90 moves the irradiation position IP along the Y direction during welding.

[0047] In Figure 7, similar to Figure 2, the area where the heating device 50 is located when viewed in the Z direction is marked with upward-sloping hatching. In this embodiment as well, similar to the first embodiment, cracking at the terminal portion EE of the welding target area WPd can be effectively suppressed by heating it with the heating device 50.

[0048] The laser welding apparatus 10 in the fourth embodiment described above also suppresses limitations on the configuration of the heating device 50 due to the welding laser irradiation unit 20.

[0049] In addition, the welding method in the fourth embodiment may be through welding or non-through welding. Furthermore, the laser welding apparatus 10 of the fourth embodiment may be provided with a cover member 60, for example, similar to the second embodiment. Also, in the laser welding apparatus 10 of the fourth embodiment, the object to be welded OWb may be welded while moving the irradiation position IP circumferentially, for example, similar to the third embodiment.

[0050] E. Fifth Embodiment: Figure 8 is the first diagram illustrating the welding target area WPe in the fifth embodiment. Figure 9 is the second diagram illustrating the welding target area WPe in the fifth embodiment. Note that in Figure 8, as in Figure 1, the welding target area WPe is hatched with a dot pattern. In this embodiment, unlike the first embodiment, the welding target area WPe does not extend to the -X side end of the workpiece OW. Therefore, the starting end SE is located in the +X direction rather than the -X end of the workpiece OW. The configuration of the laser welding apparatus 10 in the fifth embodiment is the same as in the first embodiment unless otherwise described. Even with such a configuration, it is possible to suppress the limitation of the configuration of the heating device 50 due to the welding laser irradiation unit 20. Note that, for example, even when the workpiece OW is welded through, as in the third embodiment, the starting end SE does not have to be located at the end of the workpiece OW. Also, even when the first plate-shaped member MP1 and the second plate-shaped member MP2 are arranged side by side in the plane direction, as in the fourth embodiment, the starting end SE does not have to be located at the end of the workpiece OW.

[0051] F. Other embodiments: (F1) In the above embodiment, the welded object OW is composed of two members, but it may be composed of three or more members. Also, each member constituting the welded object OW does not have to be plate-shaped, but may be rod-shaped, for example. Also, the welded object OW as a whole does not have to be plate-shaped, but may be rod-shaped, for example. Also, the welded object OW does not have to be made of aluminum, but may be made of other metals such as iron or magnesium or various alloys, or may be made of ceramics. Also, for example, the materials of the members constituting the welded object OW may be different.

[0052] (F2) In the above embodiment, the heating device 50 is positioned so as to overlap at least a portion of the end portion EE when viewed in the Z direction. In contrast, the heating device 50 does not have to be positioned so as to overlap the end portion EE when viewed along the Z direction. In this case, the heating device 50 may heat the end portion EE while being positioned so as not to overlap the end portion EE. Furthermore, the heating device 50 does not have to heat the end portion EE. In other words, the heating device 50 may heat only the portion of the welding target area WP that is different from the end portion EE.

[0053] (F3) In the above embodiment, the movement of the irradiation position IP may be achieved, for example, by moving the workpiece OW to be welded relative to the welding laser irradiation unit 20. In this case, for example, an electric actuator for moving the stage 30 may be provided, and the control unit 90 may control this electric actuator to move the workpiece OW to be welded relative to the welding laser irradiation unit 20. In this case, the heating device 50 may be configured to move together with the stage 30 relative to the welding laser irradiation unit 20.

[0054] (F4) In the above embodiment, the movement path RT of the irradiation position IP is linear or circular. However, the movement path RT does not have to be linear or circular; for example, it may be a path with a shape that combines multiple straight lines or curves, or a path with a shape that combines a straight line and a curve.

[0055] (F5) In the above embodiment, the welding laser irradiation unit 20 is configured to weld the workpiece OW while moving the irradiation position IP of the laser beam LB. In contrast, the welding laser irradiation unit 20 may weld the workpiece OW while keeping the irradiation position IP fixed.

[0056] (F6) In the above embodiment, the heating device 50 is composed of a lamp 51. However, the heating device 50 does not have to be composed of a lamp 51, and may be composed of any non-contact or contact type heating device. For example, the heating device 50 may be composed of a nichrome wire heater, a blower that blows hot air onto the workpiece OW to be welded, an induction heating device that heats the workpiece OW to be welded by induction heating, or a laser irradiation unit that irradiates the workpiece OW to preheat it.

[0057] This disclosure is not limited to the embodiments described above, and can be implemented in various configurations without departing from its spirit. For example, the technical features in the embodiments corresponding to the technical features in each form described in the summary of the invention can be replaced or combined as appropriate in order to solve some or all of the above-described problems, or to achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be deleted as appropriate. [Explanation of Symbols]

[0058] 10, 10b…Laser welding apparatus, 11…Laser oscillator, 15…Optical path, 20…Welding laser irradiation unit, 30…Stage, 31…Aperture, 50…Heating device, 51…Lamp, 52…Irradiation unit, 60…Cover member, 90…Control unit, 91…CPU, 92…Storage unit

Claims

1. A laser welding apparatus for welding a workpiece containing two or more members, A welding laser irradiation unit that faces the object to be welded and irradiates the welding target portion of the object to be welded with laser light, The system includes a heating device positioned on the opposite side of the welding laser irradiation section to the object to be welded, which preheats the area to be welded by heating the area to be welded from the opposite side, The heating device consists of a lamp that heats the area to be welded by irradiating the object to be welded with infrared rays. The irradiation part of the lamp is positioned to face the object to be welded. The laser welding apparatus further comprises a cover member positioned between the object to be welded and the irradiation unit, covering a portion of the irradiation unit and configured to reduce the laser light irradiated onto the irradiation unit. A laser welding apparatus wherein the cover member has higher heat resistance than the object to be welded and the irradiation unit.

2. A laser welding apparatus according to claim 1, The object to be welded comprises a first plate-shaped member and a second plate-shaped member. A laser welding apparatus in which the first plate-shaped member and the second plate-shaped member are stacked on top of each other.

3. A laser welding apparatus according to claim 1, The object to be welded comprises a first plate-shaped member and a second plate-shaped member. The first plate-shaped member and the second plate-shaped member are arranged side by side in the planar direction. The welding laser irradiation unit is a laser welding apparatus that welds the first plate-shaped member and the second plate-shaped member.

4. A laser welding apparatus according to claim 1, The welding laser irradiation unit is configured to weld the object to be weld while moving the irradiation position of the laser beam on the object to be welded along a predetermined movement path. The welding target portion has a starting end portion that is welded at the starting point of the movement path and a terminal end portion that is welded at the ending point of the movement path. The heating device is a laser welding apparatus that preheats the terminal portion by heating the terminal portion.

5. A laser welding apparatus according to claim 4, The object to be welded is plate-shaped, The welding laser irradiation unit irradiates the laser beam toward the plate surface of the object to be welded, The heating device is a laser welding apparatus that is positioned to overlap at least a portion of the end portion of the workpiece to be welded when viewed in the thickness direction of the workpiece.

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