阅读说明：本技术 包含铜的部件的焊接方法以及旋转电机的制造方法 (Method for welding copper-containing members and method for manufacturing rotating electric machine ) 是由 坂井哲男 黄川田昌和 于 2019-02-22 设计创作，主要内容包括：实施方式的包含铜的部件的焊接方法,具备对包含铜的第一部件与包含铜并与所述第一部件相邻地设置的第二部件进行激光焊接的工序。在对所述第一部件的焊接面及所述第二部件的焊接面照射激光时,使激光的照射位置以随着螺旋状旋转而接近螺旋的中心的方式移动,而使所述第一部件的焊接面及所述第二部件的焊接面熔融。(The method for welding a member including copper according to an embodiment includes a step of laser welding a first member including copper and a second member including copper and provided adjacent to the first member. When the welding surface of the first member and the welding surface of the second member are irradiated with the laser, the irradiation position of the laser is moved so as to approach the center of the spiral as the spiral rotates, and the welding surface of the first member and the welding surface of the second member are melted.)

1. A method of welding copper-containing parts,

the method comprises a step of laser welding a first member containing copper to a second member containing copper and disposed adjacent to the first member,

when the welding surface of the first member and the welding surface of the second member are irradiated with the laser light, the irradiation position of the laser light is moved so as to approach the center of the spiral as the spiral rotates, and the welding surface of the first member and the welding surface of the second member are melted.

2. The welding method of parts including copper according to claim 1,

the laser irradiation position is moved so as to approach the center of the spiral as the spiral rotates, and then, the laser irradiation position is moved so as to be away from the center of the spiral as the spiral rotates from the center of the spiral or the vicinity of the center of the spiral.

3. The welding method of parts including copper according to claim 1 or 2,

when the laser beam is irradiated, the first member and the second member are inclined with respect to a direction of gravity.

4. A method of welding copper-containing parts,

the method comprises a step of laser welding a first member containing copper to a second member containing copper and disposed adjacent to the first member,

the first member and the second member are inclined with respect to the direction of gravity when the laser beam is irradiated, and the inclined welding surface of the first member and the inclined welding surface of the second member are spirally irradiated with the laser beam to melt the inclined welding surface of the first member and the inclined welding surface of the second member.

5. The welding method of parts including copper according to claim 4,

when the laser light is irradiated in the spiral shape, the irradiation position of the laser light is moved so as to approach the center of the spiral as the spiral rotates, and then the irradiation position of the laser light is moved so as to be away from the center of the spiral as the spiral rotates from the center of the spiral or the vicinity of the center of the spiral.

6. The welding method of parts comprising copper according to any one of claims 3 to 5,

an angle formed by the direction of gravity and a side surface of the first member is 0 ° or more and 15 ° or less.

7. The welding method of parts comprising copper according to any one of claims 3 to 6,

an angle formed by the direction of gravity and a side surface of the second member is 0 ° or more and 15 ° or less.

8. The welding method of parts comprising copper according to any one of claims 1 to 7,

the laser light is irradiated in the spiral shape a plurality of times.

9. The welding method of parts comprising copper according to any one of claims 1 to 8,

in the process of the laser welding, the laser welding is performed,

detecting a sound having a predetermined frequency generated when at least one of the welding surface of the first member and the welding surface of the second member is melted,

detecting a start of the laser welding based on the detected sound.

10. A method of welding copper-containing parts,

the method comprises a step of laser welding a first member containing copper to a second member containing copper and disposed adjacent to the first member,

the welding method includes the steps of spirally irradiating the laser beam to melt the welding surface of the first member and the welding surface of the second member when the welding surface of the first member and the welding surface of the second member are irradiated with the laser beam,

detecting a sound having a predetermined frequency generated when at least one of the welding surface of the first member and the welding surface of the second member is melted,

detecting a start of the laser welding based on the detected sound.

11. A method of manufacturing a rotating electric machine,

a step of providing a coil containing copper in the plurality of slits,

the coil includes a plurality of segmented conductors,

in the step of providing the coil, the end faces of the plurality of segment conductors are welded by the welding method of the copper-containing member according to any one of claims 1 to 10.

Technical Field

Embodiments of the present invention relate to a welding method of a component including copper and a manufacturing method of a rotating electrical machine.

Background

Parts containing copper are sometimes laser welded to each other. For example, a rotating electrical machine such as an electric motor or a generator is provided with a coil wound around a stator. Since the coil is formed by winding a copper wire a plurality of times, flexibility is poor, and workability is significantly deteriorated when the formed coil is inserted into the slit. Therefore, the coil is divided into a plurality of members, the plurality of members are inserted into the slits, and then the ends of the plurality of members are laser-welded to each other, thereby forming the coil wound around the stator.

Here, copper is a material having a higher thermal conductivity and a higher melting point than aluminum. If the thermal conductivity is high, heat of the welded portion is easily released, and welding becomes difficult. Further, if the melting point is high, welding becomes more difficult.

In addition, copper has a low absorption rate of laser light having a wavelength in the infrared region where high output is easily formed. The absorptance of laser light varies depending on the composition ratio of the copper-containing part, the shape of the irradiation position of laser light in the copper-containing part, and the like.

Therefore, in the case of welding the members including copper to each other by laser, it is difficult to stabilize the quality of the welded portion.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2018-20340

Disclosure of Invention

Technical problem to be solved by the invention

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a method of welding copper-containing members and a method of manufacturing a rotating electrical machine, which can stabilize the quality of a welded portion.

Means for solving the problems

The method for welding a member including copper according to an embodiment includes a step of laser welding a first member including copper and a second member including copper and provided adjacent to the first member. When the welding surface of the first member and the welding surface of the second member are irradiated with the laser light, the irradiation position of the laser light is moved so as to approach the center of the spiral as the spiral rotates, and the welding surface of the first member and the welding surface of the second member are melted.

Drawings

Fig. 1 is a schematic perspective view illustrating a stator according to the present embodiment.

Fig. 2 is a schematic view for illustrating a segment conductor before being mounted to a stator core.

Fig. 3 is a schematic diagram illustrating bending of an end portion of a segment conductor and welding of an end surface of the segment conductor.

Fig. 4 is a schematic diagram for illustrating scanning of laser light.

Fig. 5 (a) is a schematic diagram illustrating a case where the irradiation position of the laser beam is linearly reciprocated. (b) Is a schematic view for illustrating a temperature distribution of an irradiated surface in the case where the irradiation shown in (a) is performed.

Fig. 6 (a) is a schematic view illustrating a case where the irradiation position of the laser beam is moved spirally from the inside toward the outside. (b) Is a schematic view for illustrating a temperature distribution of an irradiated surface in the case where the irradiation shown in (a) is performed.

Fig. 7 (a) is a schematic view illustrating a case where the irradiation position of the laser beam is moved spirally from the outside to the inside. (b) Is a schematic view for illustrating a temperature distribution of an irradiated surface in the case where the irradiation shown in (a) is performed.

Fig. 8 is a cross-sectional picture of a welded portion of a comparative example.

Fig. 9 is a cross-sectional view of the welded portion in the case where the irradiation position of the laser light is moved spirally from the outside toward the inside.

Fig. 10 (a) is a schematic view illustrating a case where the irradiation position of the laser beam is moved spirally from the outside to the inside. (b) The laser beam irradiation position is continuously moved spirally from the inside to the outside without stopping the scanning of the laser beam at the center of the spiral.

Fig. 11 is a cross-sectional view of the welded portion when the laser beam scanning illustrated in fig. 10 (a) and (b) is performed.

Fig. 12 is a schematic view for illustrating a case where laser light is irradiated in a state where the segment conductor is inclined.

Fig. 13 is a schematic diagram for illustrating scanning of laser light of other embodiments.

Fig. 14 is a schematic diagram for illustrating the configuration of a segment conductor when laser light is irradiated.

Fig. 15 is a picture for illustrating an end of a segment conductor before soldering.

Fig. 16 (a) and (b) show the case where the laser beam illustrated in fig. 4 is scanned.

Fig. 17 (a) and (b) show the case where the laser beam illustrated in fig. 9 is scanned.

Detailed Description

The present invention can be applied to, for example, a technique of butt-welding copper-containing parts to each other by laser. The form of the copper-containing member is not particularly limited. For example, the member containing copper may be in the form of a plate, a rod, a wire, or the like.

As an apparatus for butt-welding copper-containing members to each other by laser, for example, a coil provided in a rotating electrical machine such as a motor or a generator can be exemplified. Therefore, a method for manufacturing a stator will be described below as an example, and a method for welding members including copper will be described. Further, although the method of manufacturing the stator is exemplified, the present invention can also be applied to a method of manufacturing a rotor. That is, the present invention can be applied to a method for manufacturing a rotating electric machine.

Hereinafter, embodiments will be described by way of example with reference to the accompanying drawings. In the drawings, the same components are denoted by the same reference numerals, and detailed description thereof is omitted as appropriate.

Fig. 1 is a schematic perspective view illustrating a stator 1 according to the present embodiment.

As shown in fig. 1, a stator 1 is provided with a stator core 2 and a coil 3.

The stator core 2 may have a structure in which a plurality of annular magnetic members are stacked in the axial direction (Z direction in fig. 1) of the stator 1. The magnetic member can be formed of, for example, an electromagnetic steel plate (silicon steel plate). The stator core 2 has a yoke 21 and a plurality of teeth 22. The yoke 21 is cylindrical and located on the outer peripheral side of the stator core 2. The plurality of teeth 22 are provided at equal intervals on the inner peripheral surface of the yoke 21. Each of the plurality of teeth 22 protrudes from the inner circumferential surface of the yoke 21 toward the center of the stator core 2 and extends in the axial direction of the stator 1. The groove provided between the teeth 22 and the teeth 22 serves as a slit 23. The shape, number, and size of the teeth 22 are not limited to the example, and may be appropriately changed according to the application, size, specification, and the like of the rotating electric machine in which the stator 1 is installed.

The coil 3 comprises a plurality of segmented conductors 31. The segment conductor 31 may have a substantially U-shaped external shape. The segment conductor 31 is disposed inside the slit 23. The end of the segment conductor 31 protrudes from one end face of the stator core 2. The segment conductor 31 can be formed of a flat wire (flat wire) having a quadrangular cross section.

An end of one segment conductor 31 (corresponding to an example of a first segment conductor) and an end of a corresponding segment conductor 31 (corresponding to an example of a second segment conductor) are welded. In the case illustrated in fig. 1, an end of one segment conductor 31 and an end of a segment conductor 31 adjacent in the radial direction of the stator core 2 are welded. Therefore, for example, one segment conductor 31 is electrically connected to an end portion of the segment conductor 31 adjacent in the radial direction of the stator core 2 via the welded portion 31 a. A plurality of segment conductors 31 are connected in series, thereby forming 1 coil 3. In this case, the plurality of coils 3 can be wound around the inside of the stator core 2 by a plurality of turns. For example, as illustrated in fig. 1, 3 coils 3 of the U-phase, the V-phase, and the W-phase can be wound around the inside of the stator core 2 for 3 turns. The external shape, number, size, number of windings, and the like of the coil 3 and the segment conductor 31 are not limited to the example, and can be appropriately changed according to the application, size, specification, and the like of the rotating electric machine in which the stator 1 is installed.

The segment conductor 31 can be formed of a material having high electrical conductivity. The segment conductor 31 can employ a conductor containing copper. That is, in the present embodiment, the segment conductor 31 is a "member including copper". The segment conductor 31 can be formed of, for example, so-called pure copper or a material mainly composed of copper.

Next, a method for manufacturing the stator of the present embodiment will be described.

First, the stator core 2 is formed. For example, a plurality of plate-like magnetic members having the yoke 21 and the portion to become the plurality of teeth 22 are formed. For example, the magnetic member can be formed by processing an electromagnetic steel sheet having a thickness of about 0.05mm to 1.0mm by punching. Then, a plurality of magnetic body members are laminated, and the stator core 2 is formed by, for example, welding or caulking the plurality of magnetic body members. The stator core 2 can also be formed by press-molding magnetic material powder and a resin binder.

Next, the coil 3 is formed.

First, a plurality of segment conductors 31 which become components of the coil 3 are formed.

Fig. 2 is a schematic diagram illustrating the segment conductor 31 before being mounted on the stator core 2.

As shown in fig. 2, the segment conductor 31 can be formed by bending a rectangular wire having a rectangular cross section, for example. The segment conductor 31 can be formed by, for example, bending a rectangular wire into a substantially U shape. The cross-sectional dimension of the flat wire can be, for example, about 3mm to 4 mm. The flat wire may be, for example, a so-called pure copper wire, or may be a wire containing copper as a main component.

Next, each of the plurality of segment conductors 31 is attached to a predetermined slit 23 of the stator core 2. For example, the segment conductors 31 are inserted into the predetermined slits 23 from the axial direction of the stator core 2 (Z direction in fig. 1). In this case, 1 segment conductor 31 is inserted across the plurality of slits 23. The coil 3 of the present embodiment may be a so-called distributed winding coil. The coil 3 of the present embodiment may be a so-called wave-wound coil.

Then, the end portions of the segment conductors 31 are bent, and the end surfaces 31d of the adjacent segment conductors 31 are welded to each other.

Fig. 3 is a schematic diagram illustrating the bending process of the end portion of the segment conductor 31 and the welding process of the end surface 31d of the segment conductor 31.

As shown in fig. 3, the end 31b of the segment conductor 31 is bent in a direction approaching the adjacent segment conductor 31. Then, the tip end portion 31c of the segment conductor 31 is further bent in the axial direction of the stator core 2 (the Z direction in fig. 1 and 3). The front end 31c of the segment conductor 31 can overlap the front end 31c of the adjacent segment conductor 31 in the radial direction of the stator core 2. When the outer surface of the segment conductor 31 is covered with an insulator, the insulator covering the distal end portion 31c and the end surface 31d of the segment conductor 31 can be peeled off.

The bending processing as described above can be performed in a plurality of sets so that the slits 23 are shifted one by one. For example, when 3 coils 3 of U-phase, V-phase, and W-phase are formed, 3 sets of bending can be performed by shifting the mounted slits 23 one by one. In order to avoid complication, fig. 3 shows 1 set of bending and welding.

In addition, the case where the bending process is performed after the plurality of segment conductors 31 are attached to the slits 23 is exemplified, but the bending process is not limited to this. For example, the plurality of segment conductors 31 may be bent, and the plurality of segment conductors 31 may be attached to the predetermined slits 23. In this case, the segment conductors 31 subjected to the bending process can be mounted from the inside toward the outside of the stator core 2.

Next, as shown in fig. 3, the end surfaces 31d of the adjacent segment conductors 31 are welded to each other.

The welding can be performed by laser. The welding can be performed by, for example, irradiating laser light having a wavelength in the infrared region to the end surface 31d of the segment conductor 31. If a laser beam having a wavelength in the infrared region is used, a laser beam having a relatively high output can be easily irradiated. For example, the wavelength of the laser light may be set to about 1040nm to 1070 nm. For example, the output of the laser can be about 4 kW.

For example, the laser may be a Fiber laser (Fiber law), a Disk laser (Disk lab), or the like. The laser welding machine is preferably a CW laser (Continuous wave laser) capable of continuously emitting laser light. The laser welding machine is preferably a laser welding machine capable of scanning a laser beam, for example, a welding machine including a galvano mirror or the like.

The welded portion 31a is formed by welding the end surfaces 31d of the adjacent segment conductors 31 to each other. In addition, a plurality of segment conductors 31 are connected in series, thereby forming 1 coil 3. In this case, the slits 23 may be shifted one by one to form a plurality of coils 3. For example, the 3 coils 3 of the U-phase, V-phase, and W-phase can be formed by shifting the slits 23 one by one.

The welding of the end surface 31d of the segment conductor 31 will be described in detail later.

Next, the coil 3 is fixed to the stator core 2. For example, varnish (varnish) is dropped from the vertical direction of the coil 3 and supplied into the slit 23. Subsequently, the varnish is cured to fix the coil 3 to the stator core 2.

The stator 1 can be manufactured as described above.

Next, welding of the end surface 31d of the segment conductor 31 will be further described.

As described above, the segment conductor 31 includes copper. Copper has a high thermal conductivity compared to aluminum and the like. Therefore, even if the end surface 31d of the segment conductor 31 is irradiated with laser light, the generated heat is transferred to the segment conductor 31 and dissipated, and therefore the temperature of the end surface 31d is less likely to rise.

Copper has a higher melting point than aluminum and the like. Therefore, even if the end surface 31d of the segment conductor 31 is irradiated with laser light, it is difficult to melt the end surface 31d of the segment conductor 31.

In this case, if the output of the laser beam is increased, the end surface 31d of the segment conductor 31 is easily melted. In order to increase the output of the laser light, a laser light having a wavelength in the infrared region may be used. However, laser light having a wavelength in the infrared region is difficult to be absorbed by copper before melting. The absorptance of the laser light varies depending on the composition ratio of the material of the segment conductor 31 and the properties (e.g., surface roughness) of the end face 31 d.

Therefore, even if only the laser light having a wavelength in the infrared region is irradiated to the end surface 31d of the segment conductor 31, it is difficult to stabilize the quality of the welded portion.

Therefore, in the method of manufacturing the stator according to the present embodiment, welding is performed as follows.

Fig. 4 is a schematic diagram for illustrating scanning of laser light.

As shown in fig. 4, a gap may be provided between the end face 31d1 and the adjacent end face 31d 2. The end face 31d1 may be in contact with the adjacent end face 31d 2.

First, the end face 31d1 is irradiated with laser light. The irradiation start position 100 may be set near the side of the end face 31d1 on the end face 31d2 side.

Next, the irradiation position of the laser beam is scanned, and the trajectory of the irradiation position is made spiral (helical). The shape of the spiral may be circular or elliptical. For example, when the end surfaces 31d1 and 31d2 are square or rectangular with a small difference between the long side and the short side, the spiral shape may be circular. For example, when the end surfaces 31d1 and 31d2 are rectangular in shape having a large difference between the long side and the short side, the spiral shape may be an elliptical shape having a long axis substantially parallel to the long side of the end surfaces 31d1 and 31d 2.

In addition, the irradiation position of the laser can be moved from the outside to the inside of the spiral. That is, the laser light is irradiated in a spiral shape facing the inside of the end surfaces 31d1 and 31d2 with rotation, and the end surfaces 31d1 and 31d2 are melted.

Heat generated by the irradiated laser light is transmitted radially around the irradiation position. In this case, when the irradiation position is moved from the outer side of the spiral to the inner side, more heat is easily transferred to the center 110 side of the spiral. Therefore, the temperature of the laser light irradiation region can be easily increased.

In addition, the spiral irradiation can be performed a plurality of times. The temperature rise of the end surfaces 31d1 and 31d2 may be insufficient by one spiral irradiation. In such a case, the spiral irradiation may be repeated. The number of repetitions of the spiral irradiation can be appropriately changed according to the size of the end surfaces 31d1 and 31d 2. The number of repetitions of the spiral irradiation can be determined as appropriate by performing experiments or simulations, for example.

Fig. 5 (a) is a schematic diagram illustrating a case where the irradiation position of the laser beam is linearly reciprocated.

Fig. 5 (b) is a schematic diagram illustrating a temperature distribution of the irradiated surface in the case where the irradiation shown in fig. 5 (a) is performed.

Fig. 6 (a) is a schematic view illustrating a case where the irradiation position of the laser beam is moved spirally from the inside toward the outside.

Fig. 6 (b) is a schematic diagram illustrating a temperature distribution of the irradiated surface in the case where the irradiation shown in fig. 6 (a) is performed.

Fig. 7 (a) is a schematic view illustrating a case where the irradiation position of the laser beam is moved spirally from the outside to the inside.

Fig. 7 (b) is a schematic diagram illustrating a temperature distribution of the irradiated surface in the case where the irradiation shown in fig. 7 (a) is performed.

In fig. 5 (b), 6 (b), and 7 (b), the temperature distribution is represented by the shade of the single tone, and the higher the temperature, the lighter the temperature, and the lower the temperature, the darker the temperature.

If the irradiation position is linearly reciprocated, only a part of the irradiation surface can be heated as can be seen from fig. 5 (b).

If the irradiation position is moved from the inside of the spiral to the outside, a wide range of the irradiation surface can be heated as can be seen from fig. 6 (b). However, a region with a low temperature is formed in a part of the irradiation surface and below the irradiation surface.

On the other hand, when the irradiation position is moved from the outer side of the spiral to the inner side, the entire irradiation surface can be heated substantially uniformly as shown in fig. 7 (b). In addition, the lower side of the irradiation surface can be heated substantially uniformly. That is, if the irradiation position is moved from the outer side of the spiral to the inner side, the temperature of the laser irradiation region is easily increased. Therefore, the end surfaces 31d1, 31d2 containing copper having high thermal conductivity and high melting point are easily melted. The laser light absorptance of copper after melting is higher than that of copper before melting. Therefore, when the melting of the end faces 31d1, 31d2 starts, the end faces 31d1, 31d2 are further easily melted.

Fig. 8 is a cross-sectional picture of a welded portion of a comparative example. Fig. 8 is a cross-sectional view of the welded portion in the case where the irradiation position of the laser light is moved spirally from the inside toward the outside. That is, sectional views of the welded portion in the cases (a) and (b) of fig. 6.

Fig. 9 is a cross-sectional view of the welded portion in the case where the irradiation position of the laser light is moved spirally from the outside toward the inside. That is, sectional views of the welded portion in the cases (a) and (b) of fig. 7.

As described above, heat generated by the irradiated laser light is transmitted radially around the irradiation position. Therefore, as shown in fig. 6 (a), if the irradiation position is moved from the inner side of the spiral toward the outer side, it becomes difficult to increase the temperature on the center 110 side of the spiral. As a result, as shown in fig. 8, it was difficult to increase the width L1 and the penetration D1 of the welded portion.

On the other hand, if the irradiation position is moved from the outer side of the spiral to the inner side as shown in fig. 7 (b), the temperature of the center 110 side of the spiral is easily increased. Therefore, as shown in fig. 9, it is easy to increase the width L2 and the penetration D2 of the welded portion. As a result, the quality of the welded portion can be stabilized.

However, it has been found that when the irradiation position is moved from the outside to the inside of the spiral and the irradiation of the laser beam is stopped on the center 110 side of the spiral, a void 120 may be generated in the center of the bottom of the welded portion as shown in fig. 9.

The cause of the generation of the void 120 is not necessarily clear, but it is considered that a rapid temperature decrease occurs when the irradiation of the laser light is stopped on the center 110 side of the spiral, and vapor of the metal located inside the molten pool is sealed inside the welded portion.

As a result of studies conducted by the present inventors, the following findings were obtained: if the laser beam irradiation position is continuously moved spirally from the inside to the outside without stopping the scanning of the laser beam at the center 110 of the spiral or in the vicinity of the center 110, the generation of the void 120 can be suppressed. The reason why the generation of the voids 120 can be suppressed is not necessarily clear. In this case, for example, if the scanning of the laser light is not stopped at the center 110 or the vicinity of the center 110 of the spiral, the laser light is continuously irradiated at the center 110 or the vicinity of the center 110 of the spiral, and therefore, it is possible to suppress occurrence of a rapid temperature decrease. Therefore, it is considered that the metal vapor easily leaks to the outside, and the generation of the void 120 is suppressed.

Fig. 10 (a) is a schematic view illustrating a case where the irradiation position of the laser beam is moved spirally from the outside to the inside.

Fig. 10 (b) shows a case where the laser irradiation position is continuously moved spirally from the inside to the outside without stopping the scanning of the laser beam at the center 110a of the spiral. That is, the scan illustrated in fig. 10 (b) continues without interruption during the scan illustrated in fig. 10 (a).

Note that, in the scanning illustrated in fig. 10 (a) and the scanning illustrated in fig. 10 (b), the scanning is continued without interruption, and thus the scanning can be illustrated as 1 drawing, but the scanning is described as 2 drawings because the scanning is complicated.

In fig. 10 (b), the case where the irradiation is performed beyond the irradiation start position 100 is exemplified, but the irradiation may be terminated at or just before the irradiation start position 100. Further, the irradiation may be performed not at the start position 100 but in the vicinity of the start position 100. In this case, if the irradiation is performed beyond the irradiation start position 100, the molten pool can be kept warm. The end position of irradiation can be appropriately changed according to the size of the end faces 31d1 and 31d 2. The end position of irradiation can be determined appropriately by performing an experiment or simulation, for example.

In addition, as in the above, the continuous irradiation illustrated in fig. 10 (a) and (b) can be performed continuously a plurality of times. The number of repetitions of irradiation can be changed as appropriate depending on the size of the end faces 31d1, 31d2, and the like. The number of repetitions of irradiation can be determined as appropriate by performing experiments or simulations, for example.

Fig. 11 is a cross-sectional view of a welded portion when the laser beams illustrated in fig. 10 (a) and (b) are scanned.

As is clear from fig. 11, if the laser scanning illustrated in (a) and (b) of fig. 10 is performed, the width L3 and the penetration D3 of the welded portion can be increased, similarly to the welded portion illustrated in fig. 9. Further, the generation of the void 120 at the center of the bottom of the welded portion can be suppressed. That is, the quality of the welded portion can be further stabilized.

As described above, if the laser beam irradiation of the present embodiment is performed, even the segment conductor 31 including copper, which is difficult to be welded by the laser beam, can be easily welded, and the quality of the welded portion 31a can be easily stabilized.

As shown in fig. 4, 10 (a), and 10 (b), the length of the trajectory of the irradiation position on the end face 31d2 can be longer than the length of the trajectory of the irradiation position on the end face 31d 1. That is, the heating area of the end face 31d2 can be wider than the heating area of the end face 31d 1. Therefore, the amount of molten metal in the end face 31d2 is greater than the amount of molten metal in the end face 31d 1. In this case, the penetration depth of the end face 31d2 is deeper than the penetration depth of the end face 31d 1.

According to the findings obtained by the present inventors, it is preferable that the total length of the loci of the irradiation positions on the end face 31d2 be: the total length of the loci of the irradiation positions on the end face 31d1 is 6: 4-7: 3. thus, the quality of the welded portion can be improved.

In the case where the laser light L is irradiated while the segment conductor 31 is inclined as shown in fig. 12 to be described later, it is preferable that the end surface having the longer total length of the locus at the irradiation position is located above the end surface having the shorter total length of the locus at the irradiation position.

When the length of the trajectory of the irradiation position on the end face 31d2 is longer than the length of the trajectory of the irradiation position on the end face 31d1, the segment conductor 31 can be irradiated with the laser light while being inclined with respect to the gravity direction (vertical direction).

When the segment conductor 31 is inclined, the end face 31d2 having a long trajectory at the irradiation position (a wide heating region) can be positioned above the end face 31d1 in the gravity direction. Thus, the molten metal can be supplied from the end face 31d2 side where the amount of molten metal is large toward the end face 31d1 side. In this case, the end face 31d1 is also heated, and therefore molten metal is present on the surface. Therefore, the molten metals are mixed with each other in the end surface 31d1 to form the welded portion 31 a. When the molten metals are mixed with each other, the interface generation and the like can be suppressed, so that the weld strength can be suppressed from being lowered, and the quality of the welded portion 31a can be stabilized.

Fig. 12 is a schematic diagram for illustrating a case where the laser light L is irradiated in a state where the segment conductor 31 is inclined.

As shown in fig. 12, an angle formed by the gravity direction G and the side surface 31e of the segment conductor 31 is represented by θ. In this case, if the angle θ is too large, the molten metal supplied from the end face 31d2 side toward the end face 31d1 side may be discharged from the end face 31d 1.

According to the findings obtained by the present inventors, when the angle θ is 15 ° or less, it becomes easy for the molten metal to stay on the end surface 31d 1.

In this case, the laser beam L can be irradiated from the gravity direction G as shown in fig. 12. The laser light L may be emitted from a direction inclined with respect to the gravitational direction G.

When the laser beam of the present embodiment is irradiated, even the segment conductor 31 including copper, which is difficult to be welded by the laser beam, can be easily welded, and the quality of the welded portion 31a can be easily stabilized.

Here, as described above, the gap S may be provided between the end face 31d1 and the end face 31d 2. When the laser beam is irradiated to the gap S, the laser beam passes through the gap S and irradiates a member provided below the segment conductor 31 with the laser beam. Therefore, a member provided below the segment conductor 31 may be damaged by the laser beam. As described above, although copper has a low laser light absorptance, when a member provided below the segment conductor 31 includes a material having a high laser light absorptance, the member is likely to be damaged.

Therefore, when the gap S is provided between the end face 31d1 and the end face 31d2, the segment conductor 31 is preferably irradiated with the laser light while being inclined. When the segment conductor 31 is irradiated with the laser light while being inclined, the laser light irradiated to the gap S is likely to enter the side surface 31e of the segment conductor 31, and thus the laser light can be suppressed from being irradiated to a member provided below the segment conductor 31.

In this case, the angle θ formed by the gravity direction G and the side surface of the object to be welded (the side surface 31e of the segment conductor 31) may be an angle at which a part of the object to be welded (the side surface 31e of the segment conductor 31) can be seen through the gap when viewed from the laser light irradiation direction.

Fig. 13 is a schematic diagram for illustrating scanning of laser light of other embodiments.

Fig. 14 is a schematic diagram for illustrating the configuration of the segment conductor 31 when the laser light L is irradiated.

As shown in fig. 13, the irradiation start position 100 can be set between the end face 31d1 and the end face 31d 2. In addition, the irradiation position of the laser beam is scanned so that the locus of the irradiation position is spiral. The shape of the spiral can be the same as described above. The irradiation position of the laser can be moved from the outside to the inside of the spiral.

In this case, the length of the trajectory of the irradiation position in the end face 31d2 can be substantially the same as the length of the trajectory of the irradiation position in the end face 31d 1. That is, the heating region of the end face 31d2 can be set to be substantially the same as the heating region of the end face 31d 1. Therefore, the amount of molten metal in the end face 31d2 is substantially the same as the amount of molten metal in the end face 31d 1. The penetration depth in the end face 31d2 is substantially the same as the penetration depth in the end face 31d 1.

When such scanning with the laser light L is performed, as shown in fig. 14, the side surface 31e of the segment conductor 31 can be made substantially parallel to the direction of gravity (vertical direction). For example, the angle θ can be made substantially 0 °. That is, the angle θ can be set to "0 ° ≦ θ ≦ 15 °". In this case, the laser light L can be irradiated from the gravity direction G as shown in fig. 14. The laser light L may be emitted from a direction inclined with respect to the gravitational direction G.

As described above, if the gap S is provided between the end face 31d1 and the end face 31d2, a member provided below the segment conductor 31 may be damaged. Therefore, when the angle θ is 0 ° or less, it is preferable to make the end face 31d1 contact the end face 31d2 or to make the gap S as small as possible.

When the laser beam of the present embodiment is irradiated, even the segment conductor 31 including copper, which is difficult to be welded by the laser beam, can be easily welded, and the quality of the welded portion 31a can be easily stabilized.

In the above, the end face 31d1 and the end face 31d2 are illustrated as being substantially flush with each other (the end face 31d1 and the end face 31d2 have no step therebetween), but one end face may protrude from the other end face. That is, a step may be present between the end face 31d1 and the end face 31d 2. However, if the step is too large, the movement of the molten metal may be suppressed. Therefore, the step is preferably 0mm or more and 1mm or less.

Further, the present inventors have found, based on the findings obtained by the present inventors, that: when the end surfaces of the segment conductors 31 are melted, a sound having a specific frequency is generated. The main cause of the sound generation is not necessarily clear, but can be considered as follows.

When the end surfaces of the segment conductors 31 are melted to form a so-called molten pool, the molten metal in the molten pool is further heated to generate metal vapor. When the metal vapor is generated, the molten metal around the vapor is pushed away, and the molten metal vibrates. The vibration is transmitted to the air, thereby generating sound.

The frequency of the generated sound may vary depending on the composition ratio of the material of the segment conductor 31, the conditions of laser welding, the temperature of the molten metal in the molten pool, the depth of the molten pool, and the like. For example, if the depth of the molten pool becomes shallow, the frequency becomes high. For example, when the depth of the molten pool is shallow, sound having a frequency of about 1.5kHz to 3kHz is generated. When the depth of the molten pool becomes deep, sound having a frequency of 1.5kHz or less is generated.

The relationship between the frequency of the generated sound and the frequency and the depth (penetration) of the molten pool can be known in advance by performing experiments and simulations, for example.

Therefore, if a sound having a frequency determined in advance is detected, for example, the start of welding can be detected. The end of welding can be determined by time management, the number of repetitions of spiral irradiation, or the like. The time from the start to the end of welding and the number of repetitions of spiral irradiation from the start to the end of welding can be known in advance by performing experiments and simulations, for example.

In addition, when no sound is detected even after a predetermined time has elapsed after the laser irradiation, it is assumed that an abnormality has occurred, and the laser welding can be stopped.

Further, by detecting the change in frequency, the depth of the molten pool, that is, the penetration depth can be known.

As an example, the case where the method of welding the members including copper according to the present embodiment is applied to the method of manufacturing the stator 1 has been described above.

That is, the method for welding a copper-containing member according to the present embodiment may include: a first part (for example, the segmented conductor 31) containing copper and a second part (for example, the segmented conductor 31) containing copper and disposed adjacent to the first part are laser-welded. When the welding surface of the first member (for example, the end surface 31d1) and the welding surface of the second member (for example, the end surface 31d2) are irradiated with the laser light, the irradiation position of the laser light can be moved so as to approach the centers 110 and 110a of the spirals as the spirals rotate, and the welding surface of the first member and the welding surface of the second member can be melted.

In this case, the irradiation position of the laser light may be moved so as to approach the center of the spiral as the spiral rotates, and then the irradiation position of the laser light may be moved so as to be away from the center of the spiral as the spiral rotates from the center of the spiral or the vicinity of the center of the spiral.

In this case, the first member and the second member can be inclined with respect to the gravity direction when the laser beam is irradiated.

In the method of welding copper-containing members according to the present embodiment, the first member and the second member are inclined with respect to the direction of gravity when the laser beam is irradiated, and the inclined welding surface of the first member and the inclined welding surface of the second member are spirally irradiated with the laser beam to melt the inclined welding surface of the first member and the inclined welding surface of the second member.

In this case, when the laser light is irradiated in the spiral shape, the irradiation position of the laser light can be moved so as to approach the center of the spiral as the spiral rotates, and then the irradiation position of the laser light can be moved from the center of the spiral or the vicinity of the center of the spiral so as to be away from the center of the spiral as the spiral rotates.

Further, an angle formed by the direction of gravity and the side surface of the first member is preferably 0 ° or more and 15 ° or less. The angle formed by the direction of gravity and the side surface of the second member is preferably 0 ° or more and 15 ° or less.

The laser beam may be irradiated multiple times in a spiral shape.

In the laser welding step, a sound having a predetermined frequency generated when at least one of the welding surface of the first member and the welding surface of the second member is melted can be detected, and the start of laser welding can be detected based on the detected sound.

In the method of welding copper-containing members according to the present embodiment, when the welding surface of the first member and the welding surface of the second member are irradiated with laser light, the laser light is spirally irradiated to melt the welding surface of the first member and the welding surface of the second member, a sound having a predetermined frequency generated when at least one of the welding surface of the first member and the welding surface of the second member is melted is detected, and the start of the laser welding may be detected based on the detected sound.

When the method of welding the copper-containing member according to the present embodiment is applied to the method of manufacturing the rotating electrical machine, the method of manufacturing the rotating electrical machine may include a step of providing the copper-containing coil in the plurality of slits. The coil includes a plurality of segment conductors, and in the step of providing the coil, end faces of the plurality of segment conductors are welded by the above-described welding method for the copper-containing member.

The method for manufacturing the stator 1 according to the present embodiment described above is a method for manufacturing the stator 1 including the stator core 2 having the plurality of slits 23 and the coil 3 provided in the plurality of slits 23 and including the plurality of segment conductors 31. In the step of welding the end face of the first segment conductor and the end face of the second segment conductor, the end face of the first segment conductor and the end face of the second segment conductor are irradiated with laser light in a spiral shape approaching the center with rotation, and the end faces of the first segment conductor and the second segment conductor are melted.

In this case, when the laser beam is irradiated, the first segment conductor and the second segment conductor are inclined with respect to the gravity direction.

In the method of manufacturing the stator 1 according to the present embodiment, in the step of welding the end surface of the first segment conductor and the end surface of the second segment conductor, the first segment conductor and the second segment conductor are inclined with respect to the direction of gravity. The end face of the first segment conductor and the end face of the second segment conductor may be irradiated with laser light in a spiral shape to melt the end faces of the first segment conductor and the second segment conductor.

An angle formed by the direction of gravity and the side surface of the first segment conductor may be 10 ° or less.

An angle formed by the direction of gravity and the side surface of the second segment conductor may be 10 ° or less.

The laser light can be irradiated multiple times in a spiral shape.

The welding apparatus can detect a sound having a predetermined frequency generated when at least one of the end surface of the first segment conductor and the end surface of the second segment conductor is melted, and can detect the start of welding based on the detected sound.

In the method of manufacturing the stator 1 according to the present embodiment, in the step of welding the end surface of the first segment conductor and the end surface of the second segment conductor, the end surface of the first segment conductor and the end surface of the second segment conductor are spirally irradiated with laser light to melt the end surfaces of the first segment conductor and the second segment conductor. Further, a sound having a predetermined frequency generated when at least one of the end surface of the first segment conductor and the end surface of the second segment conductor is melted is detected. Then, based on the detected sound, the start of welding is detected.

(examples)

Fig. 15 is a picture for illustrating an end of the segment conductor 31 before welding.

Fig. 16 (a) and (b) show the case where the laser beam illustrated in fig. 4 is scanned.

In this case, the width W1 of the end faces 31d1 and 31d2 illustrated in fig. 4 is 3.0mm, and the width W2 of the end faces 31d1 and 31d2 is 4.0 mm. Further, the gap S between the end face 31d1 and the end face 31d2 was 0.5 mm. The maximum radius of the helix is 1.4 mm. The pitch of the helix is 0.1 mm. The wavelength of the laser is 1040nm to 1070 nm. The output of the laser was 2.9 kW. The angle θ formed by the gravity direction G and the side surface 31e of the segment conductor 31 is 10 °. The time for 1 helical irradiation was about 1 second.

Fig. 16 (a) shows a case where the number of repetitions of the spiral irradiation is 3. When the number of repetitions of the spiral irradiation is 3 times, it is found that the formation of the welded portion 31a is insufficient.

Fig. 16 (b) shows a case where the number of repetitions of the spiral irradiation is set to 4. It is found that the formation of the welded portion 31a is sufficient when the number of repetitions of the spiral irradiation is 4.

Fig. 17 (a) and (b) show the case where the laser beam illustrated in fig. 17 is scanned.

In this case, the width W1 of the end faces 31d1 and 31d2 illustrated in fig. 17 is 3.0mm, and the width W2 of the end faces 31d1 and 31d2 is 4.0 mm. Further, the gap S between the end face 31d1 and the end face 31d2 was 0 mm. That is, welding is performed in a state where the end face 31d1 is in close contact with the end face 31d 2. The maximum radius of the helix is 1.4 mm. The pitch of the helix is 0.1 mm. The wavelength of the laser is 1040nm to 1070 nm. The output of the laser was set to 3.0 kW. The angle θ formed by the gravity direction G and the side surface 31e of the segment conductor 31 is 0 °. The time for 1 helical irradiation was about 1 second.

Fig. 17 (a) shows a case where the number of repetitions of the spiral irradiation is 3. When the number of repetitions of the spiral irradiation is 3 times, it is found that the formation of the welded portion 31a is insufficient.

Fig. 17 (b) shows a case where the number of repetitions of the spiral irradiation is set to 4. It is found that the formation of the welded portion 31a is sufficient when the number of repetitions of the spiral irradiation is 4.

While the embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These new embodiments can be implemented in other various forms, and various omissions, substitutions, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalent scope thereof. The above embodiments can be combined with each other.