Method of joining a connecting member to a conductor of an insulated electric wire.

Abstract

To obtain a method for joining, for example, an improved novel connection member and an insulation-coated electric wire.SOLUTION: A method for joining a connection member and an insulation-coated electric wire conductor includes: a first step of, for example, fixing an insulation-coated electric wire and a connection member; a second step of removing insulation coating from an end part by irradiating the insulation coating of an end part fixed to the connection member in the first step with laser light from an opposite side of the connection member while circumferentially scanning the end part along the insulation coating, and by spraying a gas containing oxygen; a third step of forming a molten pool by irradiating the conductor of the end part at a fixed point with laser light from the opposite side of the connection member after the second step; a fourth step of expanding the molten pool by melting the connection member by irradiation with laser light while scanning it circumferentially after the third step; and a fifth step of solidifying the molten pool by cooling after the fourth step.SELECTED DRAWING: Figure 4

Description

Technical Field

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[0001] The present invention relates to a method for joining a connecting member and a conductor of an electric wire with an insulating coating.

Background Art

[0002] Conventionally, a method of laser welding after clamping a connecting member and a conductor of an electric wire has been known (for example, Patent Document 1 and Patent Document 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] The methods described in Patent Document 1 and Patent Document 2 are methods of laser welding a connecting member and a conductor without an insulating coating. Therefore, when applying this method to an electric wire with an insulating coating, it is necessary to partially remove the insulating coating in advance, and accordingly, the labor and cost required for the laser welding, and thus the labor and cost required for manufacturing a product including the welded portion by the laser welding, may increase.

[0005] Therefore, one of the problems of the present invention is to obtain an improved and novel method for joining a connecting member and a conductor of an electric wire with an insulating coating that can suppress the labor and cost required for manufacturing a product including a welded portion where the connecting member and the conductor of the electric wire with an insulating coating are laser welded.

Means for Solving the Problems

[0006] The present invention provides a method for joining a connecting member and a conductor of an insulated wire, comprising: a first step of fixing the insulated wire and the connecting member by crimping the connecting member so that the opening narrows, with the insulated wire having a conductor and an insulating coating surrounding the conductor passing through an opening provided in the connecting member, for example, made of a conductive metal material, and with the end of the insulated wire protruding from the connecting member; a second step of removing the insulating coating from the end of the insulating wire fixed to the connecting member in the first step by irradiating the end of the insulating coating with a laser beam from the opposite side of the connecting member while scanning the insulating coating in a circular motion along the end, and blowing an oxygen-containing gas onto the end; a third step of melting the conductor at the end of the conductor by irradiating it with a laser beam from the opposite side of the connecting member after the second step to form a molten pool; a fourth step of melting the connecting member and expanding the molten pool by irradiating it with a laser beam while scanning it in a circular motion after the third step; and a fifth step of cooling and solidifying the molten pool after the fourth step.

[0007] In the method for joining the connecting member and the conductor of the insulated wire, in the second step, the laser light may be a laser beam divided into multiple beams.

[0008] In the method for joining the connecting member and the conductor of an insulated wire, the second step may include multiple circular irradiations in which a laser beam is irradiated while scanning it in a circular motion at least once.

[0009] In the method for joining the connecting member and the conductor of an insulated wire, the second step may include, as the circular irradiation, a first circular irradiation and a second circular irradiation performed after the first circular irradiation, in which the laser light is irradiated at a lower power than the first circular irradiation.

[0010] In the method of joining the connecting member and the conductor of the insulated wire, the laser beam may be scanned with a larger radius than the first circular irradiation during the second circular irradiation.

[0011] In the method for joining the connecting member and the conductor of an insulated wire, the second step may include, as the circular irradiation, a first circular irradiation and a third circular irradiation performed after the first circular irradiation, scanning the laser beam with a larger radius than the first circular irradiation.

[0012] In the method of joining the connecting member and the conductor of the insulated wire, in the second step, the gas may be sprayed from the opposite side of the end from the connecting member toward multiple locations on the outer circumference of the end at different positions in the circumferential direction.

[0013] In the second step, the scanning speed of the laser beam spot may be faster than 10 mm / s and slower than 70 mm / s, and the output power of the laser beam may be higher than 100 W and lower than 1200 W.

[0014] In the second step, the scanning speed of the laser beam spot may be faster than 20 [mm / s], and the output power of the laser beam may be higher than 200 [W] and lower than 1000 [W].

[0015] In the third step, the laser beam irradiation time may be longer than 10 ms and shorter than 70 ms, and the laser beam output may be higher than 500 W and lower than 1000 W.

[0016] In the third step, the laser light irradiation time may be longer than 30 ms and shorter than 60 ms, and the laser light output may be higher than 700 W.

[0017] In the method for joining the connecting member and the conductor of the insulated wire, in the fourth step, the laser light may be a laser beam divided into multiple beams.

[0018] In the method of joining the connecting member and the conductor of the insulated wire, the fourth step may involve irradiating the laser beam with a lower power than that used in the third step.

[0019] In the fourth step, the scanning speed of the laser beam spot may be faster than 20 [mm / s] and slower than 70 [mm / s], and the output of the laser beam may be higher than 350 [W] and lower than 650 [W].

[0020] In the fourth step, the scanning speed of the laser beam spot may be slower than 60 [mm / s], and the output of the laser beam may be higher than 400 [W].

[0021] In the fourth step, the laser beam may be scanned in a circular shape while wobbling.

[0022] The joining method of the connecting member and the conductor of the wire with insulation coating may include a sixth step of irradiating the molten pool formed in the fourth step with a laser beam at a power lower than that in the fourth step to heat the molten pool after the fourth step and before the fifth step.

[0023] In the joining method of the connecting member and the conductor of the wire with insulation coating, in the sixth step, the laser beam may be irradiated as a laser beam divided into a plurality of beams.

Advantages of the Invention

[0024] According to the present invention, an improved and novel joining method of a connecting member and a conductor of a wire with insulation coating can be obtained.

Brief Description of the Drawings

[0025] [Figure 1] FIG. 1 is an exemplary schematic diagram of a laser processing apparatus according to an embodiment. [Figure 2] FIG. 2 is an explanatory diagram showing the concept of the principle of a diffractive optical element included in the laser processing apparatus according to the embodiment. [Figure 3] FIG. 3 is a schematic diagram showing an example of a laser beam spot formed on the surface of a processing target by the laser processing apparatus according to the embodiment. [Figure 4] FIG. 4 is an exemplary flowchart showing the procedure of the joining method of the connecting member and the conductor of the wire with insulation coating according to the first embodiment. [Figure 5] Figure 5 is an illustrative and schematic plan view showing the state in which an insulated electric wire is set in a predetermined position on the connecting member in the joining method of the first embodiment. [Figure 6] Figure 6 is an illustrative and schematic plan view showing the state in the joining method of the first embodiment in which the connecting member is crimped after the state shown in Figure 5 to fix the connecting member and the insulated wire. [Figure 7] Figure 7 is an illustrative and schematic cross-sectional view showing the state in which the tip of an insulated wire is cut so that it protrudes a predetermined length from the connecting member in the joining method of the first embodiment. [Figure 8] Figure 8 is an exemplary and schematic cross-sectional view showing the step of removing the insulating coating from the end of an insulated wire by laser irradiation and gas blowing in the joining method of the first embodiment. [Figure 9] Figure 9 is an illustrative and schematic cross-sectional view showing a step later than Figure 8 in the joining method of the first embodiment, in which the insulating coating is removed from the end of an insulated wire by laser irradiation and gas blowing. [Figure 10] Figure 10 is an illustrative and schematic cross-sectional view showing the step in the joining method of the first embodiment, in which the end of the conductor of an electric wire from which the insulating coating has been removed by irradiation with laser light is melted to form a molten pool. [Figure 11] Figure 11 is an illustrative and schematic cross-sectional view showing a step later than that shown in Figure 10 in the joining method of the first embodiment, in which the end of the conductor of the electric wire from which the insulating coating has been removed by laser irradiation is melted to form a molten pool. [Figure 12] Figure 12 is an illustrative and schematic cross-sectional view showing the step in the joining method of the first embodiment in which the connecting member is melted by irradiation with laser light to expand the molten pool. [Figure 13] Figure 13 is an exemplary and schematic cross-sectional view showing the state in which the molten pool formed in the joining method of the first embodiment has been cooled and solidified. [Figure 14]Figure 14 is an illustrative flowchart showing the procedure for joining the connecting member and the conductor of an insulated wire according to the second embodiment. [Figure 15] Figure 15 is an illustrative and schematic cross-sectional view showing the step in the joining method of the second embodiment in which the molten pool in Figure 12 is heated by laser irradiation to remove air bubbles. [Figure 16] Figure 16 is an illustrative and schematic plan view showing the scanning trajectory of a laser spot when wobbling scanning is performed on the spot in the bonding method of the third embodiment. [Modes for carrying out the invention]

[0026] Illustrative embodiments of the present invention are disclosed below. The configurations of the embodiments shown below, as well as the functions and effects brought about by such configurations, are examples only. The present invention can also be realized by configurations other than those disclosed in the following embodiments. Furthermore, according to the present invention, it is possible to obtain at least one of the various effects (including derived effects) that can be obtained by such configurations.

[0027] In each diagram, the X direction is represented by arrow X, the Y direction by arrow Y, and the Z direction by arrow Z. The X, Y, and Z directions intersect and are perpendicular to each other. The Z direction is the axial direction of the insulated wire.

[0028] Furthermore, the following embodiments include similar components. Each embodiment yields similar effects based on similar components. In the following, redundant explanations of similar components and effects may be omitted.

[0029] Furthermore, in this specification, ordinal numbers are assigned for convenience to distinguish processes, stages, components, etc., and do not limit priority or order.

[0030] [First Embodiment] [Laser processing equipment and objects to be processed] Figure 1 is a schematic diagram of a laser processing apparatus 100 that laser-welds a connecting member 10 and an insulated wire 20. In the following, the connecting member 10 and the insulated wire 20 will be referred to as the processing target W.

[0031] The connecting member 10 is made of a conductive metallic material, such as a copper-based material or an aluminum-based material. Copper-based materials include, for example, oxygen-free copper or copper alloys, and aluminum-based materials include, for example, pure aluminum or aluminum alloys. The connecting member 10 also has a plate-like shape with a substantially constant thickness in the Z direction and extending in a direction intersecting the Z direction.

[0032] The insulated wire 20 has a conductor 21 and an insulating coating 22. The conductor 21 is made of a conductive metallic material, such as a copper-based material or an aluminum-based material. The insulating coating 22 is made of an insulating synthetic resin material, for example. The conductor 21 is a round wire with a circular cross-section, and the insulating coating 22 has a tubular shape that covers the conductor 21.

[0033] The object to be processed W is set up such that an insulated wire 20 extends in the Z direction and penetrates the connecting member 10 in the Z direction, with the end 20a of the insulated wire 20 protruding from the connecting member 10 by a predetermined length. The laser processing device 100 irradiates the object to be processed W with laser light L from the opposite side of the end 20a from the connecting member 10, substantially along the opposite direction of the Z direction. The laser processing device 100 and the object to be processed W are arranged so that the Z direction is substantially vertically upward.

[0034] The laser processing apparatus 100 comprises a laser device 110, an optical head 120, an optical fiber 130, a moving mechanism 140, and a gas supply mechanism 150.

[0035] The laser device 110 has a laser oscillator and is configured to output laser light with a power of several kW, for example. The laser device 110 outputs laser light with a wavelength of 400 nm to 1200 nm, for example. The laser device 110 has a laser light source inside, such as a fiber laser, a semiconductor laser (element), a YAG laser, or a disk laser. The laser device 110 may also be configured to output multimode laser light with a power of several kW as the sum of the outputs of multiple light sources.

[0036] The optical fiber 130 optically connects the laser device 110 and the optical head 120. The optical fiber 130 guides the laser light output from the laser device 110 to the optical head 120.

[0037] The optical head 120 is an optical device that irradiates the workpiece W with laser light from the laser device 110. The optical head 120 includes a collimating lens 121, a focusing lens 122, a mirror 123, a diffractive optical element 125 (hereinafter referred to as DOE125), and a galvanoscanner 126. The collimating lens 121, focusing lens 122, mirror 123, DOE125, and galvanoscanner 126 are also referred to as optical components.

[0038] The collimating lens 121 collimates the laser light input via the optical fiber 130. The collimated laser light becomes parallel light.

[0039] The mirror 123 reflects the laser beam, which has been made parallel by the collimating lens 121, and directs it towards the galvanoscanner 126. Depending on the arrangement of the collimating lens 121 and the galvanoscanner 126, the mirror 123 may not be necessary.

[0040] The galvanoscanner 126 has multiple mirrors 126a and 126b. By changing the angles of the multiple mirrors 126a and 126b, the output direction of the laser beam L from the optical head 120 can be switched. The angles of the mirrors 126a and 126b are changed by motors (not shown) controlled by, for example, a control device. The optical head 120 can scan the laser beam L relatively on the surface of the workpiece W by changing the output direction of the laser beam L while irradiating it.

[0041] The focusing lens 122 focuses the laser light, which is emitted as parallel light by the galvanoscanner 126, and irradiates the workpiece W with the laser light L (output light). A spot of laser light L that has passed through the focusing lens 122 is formed on the surface of the workpiece W.

[0042] The DOE125 is located between the collimating lens 121 and the focusing lens 122, and between the collimating lens 121 and the galvanoscanner 126.

[0043] Figure 2 is an explanatory diagram illustrating the concept of the DOE125 principle. As shown in Figure 2, the DOE125 has a configuration in which, for example, multiple diffraction gratings 125a with different periods are superimposed. The DOE125 can shape the beam by bending or superimposing parallel light in the direction influenced by each diffraction grating 125a. The DOE125 can split laser light into multiple beams and appropriately shape the spot on the surface. The DOE125 is an example of a beam shaper.

[0044] Figure 3 is a plan view showing an example of a beam spot of laser light L irradiated from the laser processing apparatus 100 on a virtual surface Wa of the workpiece W. In the example in Figure 3, due to beam shaping by DOE125, multiple beam spots S2 are arranged circumferentially and substantially ring-shaped around a single beam spot S1 on the surface Wa. As an example, the power density of spot S2 is set lower than the power density of spot S1.

[0045] The moving mechanism 140 shown in Figure 2 can move the workpiece W and the optical head 120 relative to each other. By operating the moving mechanism 140, the laser beam L can be scanned relative to the surface of the workpiece W. That is, in this embodiment, the relative scanning of the spot of the laser beam L with respect to the surface of the workpiece W may be achieved by the operation of the galvanoscanner 126 alone, by the operation of the moving mechanism 140 alone, or by a combination of the operation of both the moving mechanism 140 and the galvanoscanner 126.

[0046] Furthermore, the gas supply mechanism 150 has a nozzle 151 that sprays oxygen-containing gas G onto the workpiece W from the opposite side of the end 20a from the connecting member 10. The nozzle 151 may be fixed to the optical head 120 or to a device that supports the workpiece W.

[0047] [Laser welding method] Figure 4 is a flowchart showing an example of the procedure for processing the object W using the laser processing apparatus 100 of the first embodiment.

[0048] First, as shown in Figure 4, the insulated wire 20 is set into the connecting member 10 with the opening 10a of the connecting member 10 passing through it (S101).

[0049] Figure 5 is a plan view showing the state in S101 where the insulated wire 20 is set in a predetermined position on the connecting member 10. As shown in Figure 5, the connecting member 10 is provided with an opening 10a that penetrates in the Z direction, and an arm 10b that extends in the X direction so as to sandwich the opening 10a. The opening 10a is configured as a notch that is open in the X direction at the X-direction end 10c of the connecting member 10. In this case, the insulated wire 20 is inserted in the opposite direction to the X direction until it reaches the bottom of the opening 10a, and the position shown in Figure 5 where it abuts the bottom of the opening 10a becomes the set position of the insulated wire 20.

[0050] Next, as shown in Figure 4, after S101, the connecting member 10 is crimped so that the opening 10a narrows, and the insulated wire 20 and the connecting member 10 are fixed together (S102).

[0051] Figure 6 is a plan view showing the state in S102 where the opening 10a is narrowed by crimping the connecting member 10, and the insulated wire 20 and the connecting member 10 are fixed together. As shown in Figures 5 and 6, in this example, a pressing force F is applied to the two arms 10b, which closes and narrows the opening 10a as a notch, thereby fixing the insulated wire 20 and the connecting member 10 together. S102 is an example of the first step. Note that the shape of the opening 10a and the crimping method are not limited to the examples in Figures 5 and 6.

[0052] Next, as shown in Figure 4, after S102, the tip 20a1 of the end 20a (see Figure 7) of the insulated wire 20 is cut off (S103) so that the end 20a of the insulated wire 20 protrudes from the connecting member 10 by a predetermined length Lt.

[0053] Figure 7 is a cross-sectional view showing the state in S103 where the tip 20a1 of the end 20a is cut. In S101 and S102, the insulated wire 20 is operated in such a way that its end 20a protrudes longer than a predetermined length Lt. Then, in S103, the tip 20a1 of the end 20a is cut by a blade B of a cutting device or tool that moves intersecting the Z direction, for example. The predetermined length Lt is set to 3 mm when the diameter of the conductor 21 is 1.1 mm. The predetermined length Lt may also be called the protruding length.

[0054] Next, as shown in Figure 4, after S103, the insulating coating 22 on the end 20a is removed by irradiating it with laser light L while blowing oxygen-containing gas G (S104). S104 is an example of the second step.

[0055] Figures 8 and 9 are cross-sectional views showing the process in S104 of removing the insulating coating 22 from the end 20a of the insulated wire 20 by irradiation with laser light L and spraying with gas G, while Figure 9 shows a stage later than that shown in Figure 8.

[0056] In step S104, the insulating coating 22 is carbonized by irradiating it with laser light L while blowing oxygen-containing gas G onto it, and the residue R generated by the carbonization is blown away. Through diligent research by the inventors, it has been found that in step S104, in order to more reliably and efficiently carbonize the insulating coating 22 and remove the residue R, and to form a higher quality welded joint 30 (see Figure 13), it is preferable to perform circular irradiation multiple times, as shown in Figures 8 and 9, in which the laser light L is irradiated in a circular motion at approximately constant speed for at least one full rotation (360°) around the central axis C of the insulated wire 20 with predetermined radii R1 and R2.

[0057] Here, it was found that in each rotation of irradiation in S104, it is preferable to set the position of the center of the laser beam L spot and the size (radius) of the spot so that the laser beam L irradiates the insulating coating 22 and avoids irradiating the conductor 21 as much as possible. In S104, it was found that when the conductor 21 melts due to irradiation with the laser beam L, residue of the insulating coating 22 is incorporated into the molten pool of the conductor 21, and consequently, residue of the insulating coating 22 is mixed into the welded joint 30 that joins the conductor 21 and the connecting member 10, which may cause undesirable events such as a decrease in joint strength and an increase in electrical resistance.

[0058] Furthermore, it was found that in the initial circular irradiation in S104 (Figure 8), the radius R1 of the scanning trajectory of the center of the laser beam L spot is set so that the center of the laser beam L spot is scanned approximately along the center in the thickness direction of the insulating coating 22, and in the later circular irradiation (Figure 9), it is preferable to set the radius R2 of the scanning trajectory of the center of the laser beam L spot to be larger than the radius R1 of the initial circular irradiation. This allows for even carbonization of the insulating coating 22 in the initial circular irradiation, and then in the later circular irradiation, carbonization of the uncarbonized insulating coating 22 while suppressing the thermal effect on the conductor 21, and removal of the residue R. Therefore, by performing multiple circular irradiations in this manner, it is possible to achieve both more reliable and more efficient removal of the insulating coating 22 and the formation of a higher quality welded joint 30 with less residue R contamination. The circular irradiation in Figure 8 is an example of the first circular irradiation, and the circular irradiation in Figure 9 is an example of the third circular irradiation.

[0059] Furthermore, it was found that in the later circular irradiation in S104 (Figure 9), it is preferable to use a lower power of the laser beam L than in the initial circular irradiation (Figure 8). This allows for even carbonization of the insulating coating 22 in the initial circular irradiation, and then, in the later circular irradiation, carbonization of the uncarbonized insulating coating 22 while suppressing the thermal impact on the conductor 21, as well as removal of the residue R. Therefore, by performing multiple circular irradiations in this manner, it is possible to achieve both more reliable and efficient removal of the insulating coating 22 and the formation of a higher quality welded joint 30 with less residue R contamination. The circular irradiation in Figure 8 is an example of the first circular irradiation, and the circular irradiation in Figure 9 is an example of the second circular irradiation.

[0060] Furthermore, in S104, it is crucial to ensure that carbonization and residue R are removed evenly over the entire circumference of the insulating coating 22, or in other words, to suppress variations in the removal of carbonization and residue R depending on the circumferential position. From this perspective, the multiple nozzles 151 that supply gas G are arranged so that the oxygen-containing gas G is sprayed onto multiple locations on the outer circumference of the end portion 20a at different circumferential positions. In the example shown in Figures 8 and 9, the number of nozzles 151, i.e., the number of gas G supply locations, is 2, but it is not limited to this and may be 3 or more. For example, if the number of nozzles 151 is n (where n is an integer of 2 or more), the nozzles 151 are arranged so that, in a plan view seen in the opposite direction of the Z direction, gas G is supplied to multiple locations on the outer circumference of the end portion 20a that are (360 / n)° apart in the circumferential direction around the central axis C.

[0061] Furthermore, in S104, it was found that if the spot of the laser beam L is too small, the carbonization area of ​​the insulating coating 22 due to irradiation with the laser beam L becomes narrower, making it difficult to quickly remove the insulating coating 22. From this perspective, in S104, as shown in Figure 3, the irradiation area of ​​the spot of the laser beam L is made larger by using DOE125 compared to when DOE125 is not used. This makes it possible to remove the insulating coating 22 more efficiently and quickly.

[0062] Furthermore, through experimental studies, the inventors found a suitable scanning speed and laser beam output range for S104. [Table 1] Table 1 shows the quality of the performance or condition of the welded joint 30 after S107 for various cases where the scanning speed [mm / s] on the Z-direction end face of the spot end 20a in S104 and the laser beam output [W] of the laser device 110 are changed. ◎ indicates that almost no residue R remains and the conductor 21 is almost completely melted, resulting in favorable performance or condition such as low electrical resistance, high joint strength, and low spatter after S107. ○ indicates that some residue R remains or the conductor 21 is slightly melted, but the required performance or condition such as electrical resistance, joint strength, and spatter count is met after S107. × indicates that there is insufficient energy and residue R remains, or there is excess energy and a molten pool of conductor 21 mixed with residue R of the insulating coating 22 is formed, resulting in the required performance or condition such as electrical resistance, joint strength, and spatter count being not met after S107. From this perspective, it was found that the scanning speed is preferably faster than 10 mm / s and slower than 70 mm / s, and more preferably faster than 20 mm / s. Furthermore, it was found that the output is preferably higher than 100 W and lower than 1200 W, and more preferably higher than 200 W and lower than 1000 W.

[0063] Next, as shown in Figure 4, after S104, the conductor 21 at the end 20a from which the insulating coating 22 has been removed is melted by irradiation with laser light L (S105). S105 is an example of the third step.

[0064] Figures 10 and 11 are cross-sectional views showing the process of melting the end portion 20a to form a molten pool M in S105, with Figure 11 showing a later stage than that shown in Figure 10. As shown in Figures 10 and 11, in S105, a laser beam L is fixedly irradiated onto the conductor 21 of the end portion 20a from the opposite side of the connecting member 10 to melt the conductor 21 and form a molten pool M. The laser beam L is irradiated towards the tip of the end portion 20a in the Z direction, along the central axis C, and in the opposite direction of the Z direction. In addition, in S105, the laser beam L is irradiated with a higher power than in S104.

[0065] Furthermore, through experimental studies, the inventors found suitable irradiation times and laser light output ranges for S105. [Table 2] Table 2 shows the quality of the performance or condition of the welded joint 30 after S107 for various cases where the irradiation time of the laser beam L in S105 and the output [W] of the laser beam of the laser device 110 are changed. ◎ indicates that the end portion 20a melted down to the base, forming an appropriate molten pool M, and after S107, suitable performance or condition such as low electrical resistance, high joint strength, and low spatter was obtained. ○ indicates that the molten pool M was slightly small, leaving a small portion of the base of the end portion 20a, or the molten pool M was slightly large and in a slightly unstable state, but the required performance or condition such as electrical resistance, joint strength, and spatter count was met after S107. × indicates that the required performance or condition such as electrical resistance, joint strength, and spatter count was not met after S107, either because the molten pool M was too small due to insufficient energy, or because the molten pool M was blown away due to excessive energy. From this perspective, it was found that the irradiation time is preferably longer than 10 ms and shorter than 70 ms, and more preferably longer than 30 ms and shorter than 60 ms. Furthermore, it was found that the output is preferably higher than 500 W and lower than 1000 W, and more preferably higher than 700 W.

[0066] Next, as shown in Figure 4, after S105, the molten pool M is expanded to the connecting member 10 by irradiation with laser light L (S106). S106 is an example of the fourth step.

[0067] Figure 12 is a cross-sectional view showing the process of expanding the molten pool M by melting the connecting member 10 by irradiation with laser light L. Through diligent research by the inventors, it has been found that in S106, as shown in Figure 12, it is preferable to irradiate the laser light L in a circular motion around the central axis C at a predetermined radius R3 for at least one full rotation (360°) at a substantially constant velocity.

[0068] Furthermore, it was found that in S106, if the power of the laser beam L is too high, the movement of the molten pool M becomes more turbulent, potentially leading to spatter and voids. From this perspective, in S106, the laser beam L is irradiated at a lower power than in S105. This makes it possible to achieve higher quality welding with less spatter and voids.

[0069] Furthermore, it was found that the scanning trajectory, i.e., the irradiation position of the laser beam L, is preferably located at the periphery of the molten pool M or near the boundary (outer edge) of the connecting member 10 with the molten pool M. It was found that if the irradiation position is too close to the central axis C, the molten pool M cannot be efficiently enlarged. From this viewpoint, the radius R3 of the scanning trajectory of the center of the laser beam L spot is set to be approximately equivalent to the radii R1 and R2 in S104, for example.

[0070] Furthermore, in S106, it was found that if the laser beam L spot is too small, the temperature difference depending on the location of the molten pool M tends to increase, causing the movement of the molten pool M to become more turbulent, which may lead to spatter and voids. From this perspective, in S106, as shown in Figure 3, the irradiation range of the laser beam L spot is made larger by using DOE125 compared to when DOE125 is not used, and the power distribution of spots S1 and S2 is adjusted appropriately. This reduces the temperature difference depending on the location of the molten pool M, stabilizes the molten pool M, and enables higher quality welding with less spatter and voids.

[0071] Furthermore, through experimental studies, the inventors found a suitable scanning time and laser beam output range for S106. [Table 3] Table 3 shows the performance or condition of the welded joint 30 after S107 for various cases in which the scanning speed of the laser beam L spot on the molten pool M in S106 and the output [W] of the laser beam of the laser device 110 are changed. ◎ indicates that a molten pool M and thus the welded joint 30 of an appropriate size are formed and suitable performance or condition such as low electrical resistance, high joint strength, and low spatter is obtained after S107. ○ indicates that the molten pool M and thus the welded joint 30 are somewhat narrow or somewhat wide, but the required performance or condition such as electrical resistance, joint strength, and spatter count is met after S107. × indicates that the molten pool M and thus the welded joint 30 are too narrow due to insufficient energy, or the molten pool M is blown away due to excessive energy, and the required performance or condition such as electrical resistance, joint strength, and spatter count is not met after S107. From this perspective, it was found that the scanning speed is preferably faster than 20 mm / s and slower than 70 mm / s, and more preferably slower than 60 mm / s. Furthermore, it was found that the output is preferably higher than 350 W and lower than 650 W, and more preferably higher than 400 W.

[0072] Next, as shown in Figure 4, after S106, the molten pool M is cooled and solidified, forming the welded joint 30 (see Figure 13) (S107). S107 is an example of the fifth step.

[0073] Figure 13 is a cross-sectional view showing the state in which the molten pool M formed in S105 and S106 has solidified to form a welded joint 30. The molten pool M is cooled and solidified by natural cooling or forced cooling to become a welded joint 30, thereby joining the connecting member 10 and the insulated electric wire 20 via the welded joint 30.

[0074] As described above, according to this embodiment, in step S102 (first step), the insulated wire 20 and the connecting member 10 are fixed with the end portion 20a protruding from the connecting member 10. Then, in step S104 (second step) following S102, the insulating coating 22 is carbonized and removed by blowing oxygen-containing gas G onto the end portion 20a while irradiating it with laser light L. Then, in step S105 (third step) following S104, the conductor 21 of the end portion 20a from which the insulating coating 22 has been removed is melted by irradiation with laser light L to form a molten pool M. Then, in step S106 (fourth step) following S105, the molten pool M is expanded to the connecting member 10 by irradiation with laser light L. Finally, in step S107 (fifth step) following S106, the molten pool M is cooled and solidified, forming a welded joint 30 that joins the conductor 21 and the connecting member 10 and provides an electrical connection. According to this embodiment, since the laser processing apparatus 100 can perform both the removal of the insulating coating 22 and laser welding, the effort and cost required to manufacture a product including the welded part 30 can be reduced compared to the case where the insulating coating 22 is removed separately before laser welding.

[0075] [Second Embodiment] Figure 14 is a flowchart showing an example of the procedure for processing the object W using the laser processing apparatus 100 of the second embodiment.

[0076] As can be seen by comparing Figure 14 with Figure 4, in this embodiment, after S106 (fourth step) and before S107 (fifth step), a step (S108) is performed in which the molten pool M is heated to remove voids v (air bubbles, see Figure 15). S108 is an example of a sixth step.

[0077] Figure 15 is a cross-sectional view showing the process of heating the molten pool M by irradiation with laser light L to remove voids v. In S108, as shown in Figure 15, the molten pool M is heated by irradiating it with laser light L from the opposite side of the connecting member 10. The laser light L is irradiated towards the leading edge of the molten pool M in the Z direction, along the central axis C, and in the opposite direction to the Z direction. Also, in S108, the laser light L is irradiated with a lower power than in S106. As a result, voids v present in the molten pool M rise within the molten pool M and are discharged outside the molten pool M. According to this embodiment, a weld 30 with fewer voids v and of higher quality can be obtained.

[0078] Furthermore, in S108, it was found that if the spot of the laser beam L is too small, the temperature difference depending on the location of the molten pool M tends to be large, which may lead to differences in the degree of void v discharge depending on the location of the molten pool M, and consequently, differences in the remaining rate of void v depending on the location of the weld 30. From this perspective, in S106, as shown in Figure 3, the irradiation range of the spot of the laser beam L is made larger by using DOE125 compared to when DOE125 is not used. This makes it possible to achieve higher quality welding with less difference in the remaining rate of void v depending on the location of the weld 30.

[0079] [Third Embodiment] Figure 16 is a plan view showing the scanning trajectory Pt of the laser beam L spot when wobbling scanning is performed on the spot of the laser beam L in the fourth step of the third embodiment. In this embodiment, the spot of the laser beam L is scanned circumferentially while wobbling on the surface of the molten pool M. Specifically, the spot of the laser beam L rotates in a uniform circular motion clockwise with a first diameter D1, and the center of rotation of the rotation circle C1 moves circumferentially in a uniform circular motion clockwise around the central axis C with a second diameter D2. Furthermore, assuming that the rotation center is stationary, the movement trajectory is defined as rotation circle C1, and the movement trajectory of the rotation center is defined as movement circle C2. The radius of rotation circle C1, i.e., D1 / 2, is set to be smaller than the radius of movement circle C2, i.e., D2 / 2. As a result, the scanning trajectory Pt traces a spiral trajectory as shown in Figure 16.

[0080] When a laser beam L is irradiated onto the molten pool M, sublimation gas is generated at the irradiated location, and the pressure of this sublimation gas pushes the molten pool M, i.e., the molten metal material, outwards from the irradiated location. Therefore, in the case of wobbling, the molten pool M is pushed outwards radially in the direction of the rotation as the irradiation location (spot) rotates. Consequently, in this embodiment, wobbling allows the molten pool M to be expanded more efficiently in a shorter time in a direction intersecting the Z direction, and consequently, the welded portion 30 expanded in a direction intersecting the Z direction can be formed more efficiently in a shorter time.

[0081] Furthermore, in the example shown in Figure 16, the pivot point of the spot (moving circle C2) passes through region A1, located in front of the central axis C in the X direction, only once, while passing through region A2, located behind the central axis C in the X direction, twice. In this way, the energy density may be varied depending on the location.

[0082] Although embodiments of the present invention have been illustrated above, these embodiments are merely examples and are not intended to limit the scope of the invention. The above embodiments can be implemented in various other forms, and various omissions, substitutions, combinations, and modifications can be made without departing from the spirit of the invention. Furthermore, each configuration, shape, and other specifications (structure, type, orientation, model, size, length, width, thickness, height, number, arrangement, position, material, etc.) can be modified as appropriate. [Explanation of symbols]

[0083] 10…Connecting member 10a…Aperture 10b...arm 10c...end 20…Insulated wire 20a...end 20a1...tip 21...Conductor 22...Insulating coating 30... Welded part 100…Laser processing equipment 110…Laser device 120…Optical head 121...Collimating lenses 122... Focusing lens 123...Mirror 125...Diffractive optical element (DOE) 125a...Diffraction grating 126... Galvanometer Scanner 126a, 126b…Mirror 130… Fiber optic 140...Movement mechanism 150... Gas supply mechanism 151…Nozzle A1…area A2…area B...blade C…Central axis C1...Swivel Circle C2...Moving Circle D1…first diameter D2…Second diameter F...Pressure G... Gas L... Laser light Lt…Predetermined length M...Melting pool Pt... Scanning trajectory S1... Spot S2... Spot R...Residue R1~R3…Radius v...Void W...Item to be processed Wa... Surface X…direction Y... Direction Z…direction

Claims

1. A first step involves fixing the insulated wire and the connecting member by crimping the connecting member so that the opening narrows, with the end of the insulated wire protruding from the connecting member, through an opening provided in the connecting member made of a conductive metal material, and the end of the insulated wire protruding from the connecting member. A second step involves irradiating the insulating coating of the end fixed to the connecting member in the first step with a laser beam from the opposite side of the connecting member, scanning the insulating coating in a circular motion along the end, and blowing an oxygen-containing gas onto the end to remove the insulating coating from the end; A third step is performed after the second step, in which a laser beam is continuously irradiated onto the conductor at the end from the opposite side of the connecting member to melt the conductor and form a molten pool. A fourth step is to expand the molten pool by irradiating the connecting member with laser light while scanning it in a circular motion, following the third step described above. A fifth step is to cool and solidify the molten pool after the fourth step, A method for joining a connecting member and a conductor of an insulated wire, comprising the following:

2. The method for joining a connecting member and a conductor of an insulated wire according to claim 1, wherein in the second step, laser light divided into multiple beams is irradiated as the laser light.

3. The method for joining a connecting member and a conductor of an insulated wire according to claim 1 or 2, wherein the second step includes multiple circular irradiations in which a laser beam is irradiated while scanning in a circular manner at least once.

4. The method for joining a connecting member and a conductor of an insulated wire according to claim 3, wherein the second step includes, as the circular irradiation, a first circular irradiation and a second circular irradiation performed after the first circular irradiation and irradiating with the laser light at a lower power than the first circular irradiation.

5. The method for joining a connecting member and a conductor of an insulated wire according to claim 4, wherein in the second circular irradiation, the laser beam is scanned at a larger radius than the first circular irradiation.

6. The method for joining a connecting member and a conductor of an insulated wire according to claim 3, wherein the second step includes, as the circular irradiation, a first circular irradiation and a third circular irradiation performed after the first circular irradiation and scanning the laser light at a larger radius than the first circular irradiation.

7. The method for joining a connecting member and an insulated wire conductor according to claim 1 or 2, wherein in the second step, the gas is blown from the opposite side of the end to the connecting member toward multiple locations on the outer circumference of the end that are at different positions in the circumferential direction.

8. The method for joining a connecting member and an insulated wire conductor according to claim 1 or 2, wherein in the second step, the scanning speed of the laser beam spot is faster than 10 [mm / s] and slower than 70 [mm / s], and the output of the laser beam is higher than 100 [W] and lower than 1200 [W].

9. The method for joining a connecting member and an insulated wire conductor according to claim 8, wherein in the second step, the scanning speed of the laser beam spot is faster than 20 [mm / s], and the output of the laser beam is higher than 200 [W] and lower than 1000 [W].

10. The method for joining a connecting member and an insulated wire conductor according to claim 1 or 2, wherein in the third step, the irradiation time of the laser light is longer than 10 [ms] and shorter than 70 [ms], and the output of the laser light is higher than 500 [W] and lower than 1000 [W].

11. The method for joining a connecting member and an insulated wire conductor according to claim 10, wherein in the third step, the irradiation time of the laser light is longer than 30 [ms] and shorter than 60 [ms], and the output of the laser light is higher than 700 [W].

12. The method for joining a connecting member and a conductor of an insulated wire according to claim 1, wherein in the fourth step, laser light divided into multiple beams is irradiated as the laser light.

13. A method for joining a connecting member and a conductor of an insulated wire according to claim 1 or 12, wherein in the fourth step, laser light is irradiated with a lower power than in the third step.

14. The method for joining a connecting member and an insulated wire conductor according to claim 1 or 2, wherein in the fourth step, the scanning speed of the laser beam spot is faster than 20 [mm / s] and slower than 70 [mm / s], and the output of the laser beam is higher than 350 [W] and lower than 650 [W].

15. The method for joining a connecting member and an insulated wire conductor according to claim 14, wherein in the fourth step, the scanning speed of the laser beam spot is slower than 60 [mm / s] and the output of the laser beam is higher than 400 [W].

16. The method for joining a connecting member and a conductor of an insulated wire according to claim 1 or 12, wherein in the fourth step, the laser beam is scanned circumferentially while wobbling.

17. A method for joining a connecting member and a conductor of an insulated wire according to claim 1, further comprising a sixth step, after the fourth step and before the fifth step, of heating the molten pool formed in the fourth step by irradiating it with laser light at a lower power than that of the fourth step.

18. The method for joining a connecting member and a conductor of an insulated wire according to claim 17, wherein in the sixth step, laser light divided into multiple beams is irradiated as the laser light.

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