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    • 专利摘要:
    The present invention relates to a laser welding method for flat wires in which the side surfaces 23a, 23b) are joined at the ends of the first and second flat wires 20a, 20b covered with insulating films, the side surfaces (23a, 23b) being separated from the insulating films, and a laser beam (1b) is applied to the end surfaces (24a, 24b) of the first and second flat wires to weld the side surfaces (23a, 23b). This method includes: applying the laser beam (lb) in an arc form within the end surface (24a) of the first flat wire to form a molten puddle (30) and gradually increasing the diameter of a wire-shaped application path. laser beam arc (lb) within the end surface (24a) of the first flat wire to allow the molten pool (30) to reach the side surfaces (23a, 23b).
    公开号:BR102017016491A2
    申请号:R102017016491-8
    申请日:2017-07-31
    公开日:2018-02-27
    发明作者:Nakamura Hideo
    申请人:Toyota Jidosha Kabushiki Kaisha；
    IPC主号:
    专利说明:

    (54) Title: LASER WELDING METHOD FOR FLAT WIRES (51) Int. Cl .: B23K 26/20; B23K 26/21; B23K 26/322 (52) CPC: B23K 26/206, B23K 26/21, B23K 26/20, B23K 26/322 (30) Unionist Priority: 08/02/2016 JP 2016152242 (73) Holder (s): TOYOTA JIDOSHA KABUSHIKI KAISHA (72) Inventor (s): HIDEO NAKAMURA (74) Attorney (s): DANIEL ADVOGADOS (ALT.DE DANIEL & CIA) (57) Abstract: The present invention relates to a laser welding method for flat wires on which the side surfaces (23a, 23b) are joined at the ends of the first and second flat wires (20a, 20b) coated with insulating films, the side surfaces (23a, 23b) being separated from the insulating films, and a bundle laser (LB) is applied to the end surfaces (24a, 24b) of the first and second flat wires to weld the side surfaces (23a, 23b). This method includes: applying the laser beam (LB) in an arc shape within the end surface (24a) of the first flat wire to form a melted puddle (30) and gradually increasing the diameter of an application-shaped path arc of the laser beam (LB) within the end surface (24a) of the first flat wire to allow the molten pool (30) to reach the side surfaces (23a, 23b).
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    1/23
    LASER WELDING METHOD FOR FLAT WIRES.
    BACKGROUND OF THE INVENTION
    1. Field of the invention [001] The present invention relates to a laser welding method for flat wires.
    2. Description of the related technique [002] A motor stator includes a stator core and a plurality of segmented coils that are mounted in slots in the stator core. Each segmented coil is typically a flat wire coated with an insulating film. The ends of the segmented coils are joined by welding, etc.
    [003] Japanese Patent Application Publication 2013-109948 discloses a laser welding method for flat wires that are used for segmented coils, for example. In JP 2013-109948 A, a pair of flat wires coated with insulating films is separated from the insulating films by the side surfaces at their ends and then those side surfaces at the ends are joined and a laser beam is applied to the end surfaces of the flat wires to weld the side surfaces at the ends.
    SUMMARY OF THE INVENTION [004] The present inventors have encountered the following problem with the laser welding method for flat wires disclosed in JP 2013-109948 A. Figure 16 is a side view of a joint part illustrating the problem with the method of laser welding disclosed in JP 2013-109948 A. As shown in figure 16, a side surface 53a of a flat wire 50a has a step between a part where an insulating film 51a is separated and the other part where the insulating film 51a is not separate. Similarly, a side surface 53b of a flat wire 50b has a step between a part where an insulating film 51b is separated and the other part where the insulating film 51b is not separated. In addition to
    Petition 870170054618, of 7/31/2017, p. 34/70
    2/23 further, although this is not shown, the end surfaces 54a, 54b undergo a cutting process, so that some burrs and depressions occur on the end surfaces 54a, 54b. For these reasons, a free space is left between the side surfaces 53a, 53b even when the flat wires 50a, 50bv are attached to the joint. In figure 16, the dashed lines indicated inside the flat wires 50a, 50b represent sections of the conductor 52a, 52b.
    [005] According to the laser welding method disclosed in JP 2013109948 A, a LB laser beam is applied to the side surfaces 53a, 53b. Thus, as shown in figure 16, the LB laser beam can enter the free space between them and damage the insulating films 51a, 51b of the flat wires 50a, 50b. Furthermore, the LB laser beam can pass through that free space and damage the insulating films of other flat wires, for example.
    [006] The present invention features a laser welding method for flat wires by which the adverse effects caused by a laser beam entering a free space between the side surfaces to be joined can be reduced.
    [007] One aspect of the present invention is a laser welding method for flat wires, in which a first side surface is joined at a first end of a first flat wire coated with a first insulating film, the first side surface being separated from the first insulating film, and a second side surface at a second end of a second flat wire coated with a second insulating film, the second side surface being separated from the second insulating film, and a laser beam is applied to a first end surface of the first flat wire and a second end surface of the second flat wire to weld together the first side surface and the second side surface, the laser welding method including: applying the laser beam in an arc shape within the first surface of far end
    Petition 870170054618, of 7/31/2017, p. 35/70
    3/23 to form a melted puddle and apply the laser beam within the first end surface while gradually increasing the diameter of an arc-shaped path of the laser beam to allow the melted puddle to reach the first side surface and the second side surface.
    [008] In this aspect of the present invention, the laser beam is applied in an arc shape within the end surface of the first flat wire to form a melted puddle, and the arc beam path diameter of the laser beam is gradually increased to allow the melted pool to reach the first side surface and the second side surface. According to this configuration, it is possible to fill the free space between the first side surface and the second side surface with the melted puddle without the laser beam being applied between the first side surface and the second side surface and thus prevent the beam from enter this free space. As a result, the adverse effects caused by the laser beam entering the free space between the side surfaces can be reduced.
    [009] The shape of the arc can be a circular shape or an elliptical shape. According to this configuration, the laser beam can be applied along a smooth path, which is less likely to cause a disturbance in the melted pool, so that the splash can be prevented.
    [010] The shape of the arc can be a rectangular shape.
    [011] The shape of the arc can be a spiral shape.
    [012] The shape of the arc can be an elliptical shape and the major geometric axis of the ellipse can be parallel to the first side surface and the second side surface. Being “parallel” here is a concept including not only being exactly parallel, but also being “substantially parallel” which means being parallel as judged by technical common sense. According to this configuration, the melted puddle can reach a wide area of free space between the first
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    4/23 side surface and the second side surface in a short time.
    [013] On the first end surface, the laser beam can be applied to only a region of the first end surface that is located on the side of the first side surface in relation to a starting position of applying the laser beam.
    [014] The laser beam can be applied to the second end surface as the diameter of the arc beam path of the laser beam gradually increases.
    [015] In the above aspect, the laser welding method may also include: applying another laser beam in an arc shape within the second end surface to form another molten pool and applying the other laser beam within the second surface of end while gradually increasing the diameter of an arc-shaped path of another laser beam to fuse the melted pool and the other melted pool. According to this configuration, it is possible to fill the free space between the first side surface and the second side surface with two melted puddles without the laser beam being applied between the first side surface and the second side surface and thus prevent more than the beam of the laser enter this free space. As a result, the adverse effects caused by the laser beam entering the free space between the first side surface and the second side surface can be further reduced.
    [016] In the above aspect, on the first end surface, the laser beam can be applied to only a region of the first end surface that is located on the side of the first lateral surface in relation to a starting position of the beam application. laser, and on the second end surface, the other laser beam can be applied to only a region of the second end surface which is located on the side of the second side surface in relation to an application start position of the other laser beam.
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    5/23 [017] In the above aspect, the laser beam can be applied to the second end surface, as the diameter of the arc beam path of the laser beam gradually increases and the other laser beam can be applied to the first end surface as the diameter of the arc-shaped path of the other laser beam gradually increases.
    [018] In the above aspect, the laser beam can be applied to only the first end surface and the other laser beam can be applied to only the second end surface.
    [019] The present invention can provide a laser welding method for flat wires by which the adverse effects caused by the entry of a laser beam into the free space between the first side surface and the second side surface can be reduced.
    BRIEF DESCRIPTION OF THE DRAWINGS [020] Characteristics, advantages and technical and industrial meanings of the exemplary modalities of the invention will be described below with reference to the accompanying drawings, in which equal numerals represent equal elements and in which:
    [021] Figure 1 is a perspective view showing a schematic configuration of a stator, [022] Figure 2 is a plan view showing a laser welding method for flat wires according to a first modality, [023] A figure 3 is a plan view showing the laser welding method for flat wires according to the first modality, [024] figure 4 is a side view of figure 3, [025] figure 5 is a plan view showing the method welding machine for flat wires according to the first modality, [026] Figure 6 is a block diagram showing a configuration of
    Petition 870170054618, of 7/31/2017, p. 38/70
    6/23 a laser welding device used in the laser welding method for flat wires according to the first modality, [027] Figure 7 is a graph showing the fluctuations of the plasma and reflected light, [028] Figure 8 is a side view showing a modified example of a flat wire joint part 25 20a, 20b in the flat wire laser welding method according to the first embodiment, [029] Figure 9 is a plan view showing a modified example of a trajectory of application of the laser beam in the laser welding method for flat wires according to the first modality, [030] Figure 10 is a plan view showing a modified example of the trajectory of application of the laser beam in the method of laser welding for flat wires according to the first modality, [031] Figure 11 is a plan view showing a modified example of the laser beam application path in the laser welding method for flat wires according to the first modality , [ 032] Figure 12 is a plan view showing a laser welding method for flat wires according to a second modality, [033] Figure 13 is a plan view showing the laser welding method for flat wires according to second modality, [034] Figure 14 is a plan view showing the laser welding method for flat wires according to the second modality, [035] Figure 15 is a table showing test conditions and results from example 1 and examples comparatives 1 and 2 and [036] Figure 16 is a side view of a joint part illustrating the problem with the laser welding method revealed in JP 2013-109948 A.
    DETAILED DESCRIPTION OF THE MODALITIES
    Petition 870170054618, of 7/31/2017, p. 39/70
    7/23 [037] In the following, specific embodiments as applications of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments. To clarify the illustration, the following description and drawings are appropriately simplified.
    (First modality) [038] First, an example of a stator configuration including segmented coils that are welded by a laser welding method for flat wires according to this modality will be described. Figure 1 is a perspective view showing the schematic configuration of the stator. As shown in figure 1, a stator 1, which is a motor stator, includes a stator core 10 and a plurality of segmented coils 20.
    [039] The core of stator 10 is formed by stacking annular magnetic steel sheets in an axial direction of stator 1 (a direction of the z-axis in figure 1) and has a substantially cylindrical shape as an assembly. A surface of the inner circumference of the stator core 10 is provided with teeth 11 that project to one side of the inner circumference and extend in the axial direction of the stator 1 and slots 12 that are grooves formed between the adjacent teeth 11. The segmented coils 20 are respectively mounted in slots 12.
    [040] The segmented coil 20 is an electrical wire with a rectangular cross-sectional shape, that is, a flat wire. The segmented coil 20 is typically made of pure copper, but can instead be made of a metal material having high electrical conductivity, such as aluminum or an alloy composed mainly of copper and aluminum.
    [041] Each segmented coil 20 is formed substantially in a U-shape. As shown in figure 1, the ends of segmented coils 20 (ends of the coil) protrude individually from a surface of the
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    8/23 upper end of the stator core 10. A joint part 25 is a part where the ends of the segmented coils 20 adjacent to each other in a radial direction are welded. A plurality of joint parts 25 are ordered in the annular direction in a direction of the circumference of the stator core 10. In the example of figure 1, 48 joint parts 25 are ordered in the annular direction. Four rows of joint parts 25 thus arranged in the annular direction are arranged in the radial direction.
    [042] Next, the laser welding method for flat wires according to this modality will be described with reference to figure 2 to figure 5. Figure 2, figure 3 and figure 5 are plan views showing the welding method laser for flat wires according to the first modality. Figure 4 is a side view of figure 3. The laser welding method for flat wires according to this modality is used to laser weld the joint parts 25 of the segmented coils 20 shown in figure 1. It must be understood that the xyz coordinates on the right side shown in figure 2 through figure 5 are for the convenience of describing the positional relationships between the components. The direction of the geometric axis z in figure 1 and the directions of the geometric axis z in figure 2 in figure 5 coincide mutually. Typically, a positive direction of the geometric z axis is a vertically upward direction and an xy plane is a horizontal plane.
    [043] First, as shown in figure 2, a first side surface 23a at a first end of a first flat wire (segmented coil) 20a which is separated from a first insulating film 21a and a second side surface 23b at a second end of a second flat wire (segmented coil) 20b which is separated from a second insulating film 21b are joined at joint part 25. Then, a laser beam is applied to a first end surface 24a of the first flat wire 20a in a vertically direction downward (a negative direction of the z-axis). That bundle
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    9/23 of the laser is applied in an arc shape within the first end surface 24a of the first flat wire 20a to form a melted puddle 30. The arc shape means an annular shape (closed arc) or a spiral shape (open arc) ). In the example shown, the application path of the laser beam has an elliptical shape.
    [044] Here, if the laser beam application path does not have an arc shape, the melted puddle 30 formed cannot grow. Being made of a metal material having high electrical conductivity, the first and second conductor sections 22a, 22b of the first and second flat wires 20a, 20b are also excellent in conductivity of heat. In this way, the portions melted by the application of the laser beam quickly solidify. For the same reason, the melted puddle 30 cannot be formed if the diameter of the arc-shaped application path is very large. Therefore, the melted puddle 30 is formed with a somewhat reduced diameter of the arc-shaped application path.
    [045] As shown in figure 2, in the laser welding method for flat wires according to this modality, first the laser beam is applied in an arc shape within the first end surface 24a of the first flat wire 20a to form the melted puddle 30. Thus, no laser beam is applied to the first and second side surfaces 23a, 23b. At this stage, therefore, the laser beam is prevented from entering the free space between the first side surface 23a and the second side surface 23b.
    [046] Next, as shown in figure 3, the diameter of the laser beam application path, that is, the diameter of the ellipse, is increased within the first end surface 24a of the first flat wire 20a to allow the puddle melted 30 reaches the first and second side surfaces 23a, 23b. Specifically, whenever the laser beam returns to an application start position (START indicated by the arrow in figure 3), the diameter of the ellipse being the
    Petition 870170054618, of 7/31/2017, p. 42/70
    10/23 application trajectory increases. Thus, the diameter of the melted pool 30 also increases steadily, so that, at the stage where the laser beam is applied within the first end surface 24a of the first flat wire 20a, the melted pool 30 reaches the first and second side surfaces 23a, 23b. Here, the major geometric axis of the elliptical application path is parallel to the first and second side surfaces 23a, 23b (for the long sides of the first and second flat wires 20a, 20b in the example shown). This can allow the melted puddle 30 to reach a wide area of free space between the first side surface 23a and the second side surface 23b in a short time.
    [047] As a result, as shown in the side view of figure 4, the free space between the first side surface 23a and the second side surface 23b is filled with the melted puddle 30. That is, at this stage, as shown in figure 4, the LB laser beam is not applied to the first and second side surfaces 23a, 23b and the free space between the first side surface 23a and the second side surface 23b is filled with the melted puddle 30. Thus, the beam of the LB laser is prevented from entering the free space between the first side surface 23a and the second side surface 23b.
    [048] Next, as shown in figure 5, the diameter of the laser beam application path, that is, the diameter of the ellipse, increases through the first end surface 24a of the first flat wire 20a and the second end surface 24b of the second flat wire 20b, until the melted puddle 30 grows to a desired size. Specifically, every time the laser beam returns to the application start position (START indicated by the arrow in figure 5), the diameter of the ellipse being the application path increases. When the diameter of the ellipse reaches a predetermined value, the application of the laser beam ends at the application start position (END indicated by the arrow in figure 5).
    [049] At this stage, as shown in figure 5, the laser beam passes over
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    11/23 the first and second side surfaces 23a, 23b, but the free space between the first side surface 23a and the second side surface 23b has already been filled with the melted puddle 30. Thus, the laser beam is prevented from entering the free space between the first side surface 23a and the second side surface 23b.
    [050] As described above, in the laser welding method for flat wires according to this modality, first the laser beam is applied in an arc shape within the first end surface 24a of the first flat wire 20a to form the melted puddle 30. Next, the diameter of the laser beam application path, that is, the diameter of the ellipse, increases within the first end surface 24a of the first flat wire 20a to allow the melted puddle 30 to reach the first and the second side surfaces 23a, 23b.
    [051] In other words, the free space between the first side surface 23a and the second side surface 23b is filled with the melted puddle 30 without the laser beam being applied to the first and second side surfaces 23a, 23b. Thus, the laser beam can be prevented from entering the free space between the first side surface 23a and the second side surface 23b. As a result, the adverse effects caused by the laser beam entering the free space between the side surfaces can be reduced.
    [052] Thus, in the laser welding method for flat wires according to this modality, the melted puddle 30 is formed inside the end surface of a flat wire and the melted puddle 30 grows in order to reach the free space between the first side surface 23a and second side surface 23b. It was confirmed that this method could prevent the entry of a laser beam in a free space of up to 0.15 mm.
    [053] In the laser welding method for flat wires according to this modality, the laser beam application path has an arc shape, so that the laser beam can be applied along a smooth path.
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    12/23
    Thus, heat is less likely to concentrate and splash generation can be prevented. For example, if the application path of the laser beam follows a path with tight curves, the heat is concentrated at the return points and the splash tends to occur. In addition, the growth of the melt puddle 30 can increase the diameter of the melt puddle 30 in relation to the depth of penetration of the melt puddle 30. Thus, the generation of the splash can be suppressed as the surface tension of the melted puddle 30 increases .
    [054] Next, a laser welding device used in the laser welding method for flat wires according to this modality will be described with reference to figure 6. Figure 6 is a block diagram showing the configuration of the welding device laser used in the laser welding method for flat wires according to the first modality. As shown in figure 6, the laser welding apparatus used in the flat wire laser welding method according to the first modality includes a laser oscillator 101, an LH laser head, BPF1, BPF2 pass-through filters, photoelectric conversion circuits PEC1, PEC2 and a splash determination unit 102.
    [055] The laser oscillator 101 is a high-focus laser oscillator that can oscillate a single-mode fiber laser beam with a beam diameter of 100 pm or smaller, for example. The LH laser head is a galvanizing-scanning laser head that can apply a laser beam at a rate of 500 mm / s or higher, for example. The LH laser head includes L1 to L3 lenses, a HM semitransparent mirror and M1, M2 mirrors. The LB laser beam released from the 101 laser oscillator and inserted into the LH laser head passes through the L1 lens, the HM semitransparent mirror, the L2 lens, the M1, M2 mirrors and the L3 lens in that order, and is applied to the puddle melted 30.
    [056] The reflected light from the LB laser beam reflected out of the molten puddle
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    13/23 passes through the L3 lens, the M2 mirror, the M1 mirror, the L2 lens and the HM semitransparent mirror of the LH laser head in that order and is selected by the BPF1 passband filter. Then, the reflected light selected by the BPF1 pass-through filter is converted into an electrical signal by the photoelectric conversion circuit PEC1 and inserted into the splash determination unit 102.
    [057] Meanwhile, the plasma (for example, with a wavelength of 400 to 600 nm) generated in the melted puddle 30 passes through the L3 lens, the M2 mirror, the M1 mirror, the L2 lens, and the semitransparent mirror HM of the LH laser head in that order and is selected by the BPF2 passband filter. Then, the plasma selected by the BPF2 bandwidth filter is converted into an electrical signal by the photoelectric conversion circuit PEC2 and inserted into the splash determination unit 102.
    [058] Splash determination unit 102 determines whether splash is generated in the melted puddle 30 based on observed fluctuations in at least one between the plasma and the reflected light. Figure 7 is a graph showing fluctuations in plasma and reflected light. In figure 7, the horizontal geometric axis and the vertical geometric axis represent time and intensity, respectively. As shown in figure 7, splash generation can be detected from fluctuations in plasma and reflected light. Thus, it is possible to detect the splash in real time during welding, instead of after welding. In addition, for example, when the extent or number of times the splash generation exceeds a predetermined reference value, the splash determination unit 102 determines that a weld failure has occurred and for the laser oscillator 101. Then, a current product is exchanged for a next one. Determining a weld failure like this in real time during welding, rather than after welding, can improve productivity more than is possible by technique
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    Related 14/23.
    (Modified example of the first embodiment) [059] A modified example of the first embodiment will be described with reference to figure 8. Figure 8 is a side view showing a modified example of joint part 25 of the first and second flat wires 20a, 20b in the laser welding method for flat wires according to the first modality. The xyz coordinates on the right side shown in figure 8 coincide with those in figure 2 through figure 5.
    [060] In the example shown in figure 1, the joint part 25 remains vertically (in the direction of the geometric axis z) as indicated by the dashed line of two points in figure 8. In this modified example, this part indicated by the dashed line of two points is omitted. Specifically, an angle θ that the first end surface 24a of the first flat wire 20a forms with an extension line of an outer surface is less than 90 °, so that the front end of the first flat wire 20a has a pointed shape. In addition, the first end surface 24a and the outer surface are connected to each other by an arc-shaped curved surface. According to this configuration, the quantity of the first and second flat wires 20a, 20b used can be reduced and the stator 1 can be decreased.
    [061] On the other hand, in the case of this configuration, as shown in figure 8, the first side surface 23a has a substantially triangular shape and is narrower than the first rectangular side surface 23a shown in figure 4. Thus, the production of spark tends to occur during welding at both ends of the first flat wire 20a in the direction of the width (the direction of the geometric axis x). However, in the laser welding method for flat wires according to this modality, the molten puddle 30 grows in a central part of the first flat wire 20a in the width direction (the direction of the geometric axis x)
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    15/23 while the laser beam is applied smoothly in an arc shape. Thus, such spark production at both ends can be suppressed.
    [062] In the following, modified examples of the first modality will be described with reference to figure 9 to figure 11. Figure 9 to figure 11 are plan views showing the modified examples of the application path of the laser beam in the laser welding method for flat wires according to the first modality. The xyz coordinates on the right side shown in figure 9 through figure 11 coincide with those in figure 2 through figure 5.
    [063] As shown in figure 9, the application path of the arc-shaped laser beam can have a rectangular arc shape. In the case of a rectangular path, however, the path of the laser beam must have sharp curves at the corners in contrast to a circular path. Specifically, in the case of a rectangular path, the laser beam cannot be applied smoothly to the corners, so the heat tends to be concentrated in the corners and the splash tends to occur compared to if the path had an elliptical shape or shape Circular. In other words, in the case where the laser beam application path has an elliptical shape or a circular shape, the laser beam can be applied constantly along a smooth path. Thus, splash generation can be suppressed.
    [064] As shown in figure 10, the application path of the arc-shaped laser beam can have a circular arc shape. As shown in figure 10, after a circular melt pool grows through the first end surface 24a of the first flat wire 20a and the second end surface 24b of the second flat wire 20b, that melted pool can be moved in the direction of the width of the first and the second flat wire 20a, 20b (a positive direction of the geometric axis x in the example shown). The application path of the arc-shaped laser beam does not have to be a closed arc as shown in figure 10 and
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    16/23 can instead be an open arc (spiral shape) as shown in figure 11.
    [065] With the application paths of the arc laser beam shown in figure 9 to figure 11, it is also possible to form the melted puddle 30 inside the end surface of a flat wire and increase the melted puddle 30 in a way reaching the free space between the first side surface 23a and the second side surface 23b.
    [066] That is, it is possible to fill the free space between the first side surface 23a and the second side surface 23b with the melted puddle 30 before the laser beam passes over the first and second side surfaces 23a, 23b. Thus, the laser beam can be prevented from entering the free space between the first side surface 23a and the second side surface 23b. As a result, the adverse effects caused by the laser beam entering the free space between the side surfaces can be reduced.
    (Second modality) [067] Next, a laser welding method for flat wires according to this modality will be described with reference to figure 12 to figure 14. Figure 12 to figure 14 are plan views showing the method of welding to laser for flat wires according to the second modality. The xyz coordinates on the right side shown in figure 12 through figure 14 coincide with those in figure 2 through figure 5.
    [068] First, as shown in figure 12, the first side surface 23a of the first flat wire 20a which is separated from the first insulating film 21a and the second side surface 23b of the second flat wire 20b which is separated from the second insulating film 21b are joined at joint part 25. Then, a laser beam is applied in an arc shape within the first end surface 24a of the first flat wire 20a to form a first molten pool 30a. At the same time, a laser beam is applied in an arc shape within the second
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    17/23 end surface 24b of the second flat wire 20b to form a second molten pool 30b. It is possible to apply a laser beam to the first and second end surfaces 24a, 24b at the same time by dividing the laser beam.
    [069] As shown in figure 12, in the laser welding method for flat wires according to this modality, first the laser beam is applied in an arc shape within the first end surface 24a of the first flat wire 20a to form the first melted puddle 30a. At the same time, another laser beam is applied in an arc shape within the second end surface 24b of the second flat wire 20b to form the second molten pool 30b. Thus, the laser beam is not applied to the first and second side surfaces 23a, 23b. At this stage, therefore, the laser beam is prevented from entering the free space between the first side surface 23a and the second side surface 23b.
    [070] Next, as shown in figure 13, the diameter of the laser beam application path, that is, the diameter of the ellipse, is increased within the first end surface 24a of the first flat wire 20a to allow the first melted pool 30a reaches the first and second side surfaces 23a, 23b. At the same time, the diameter of the laser beam application path, that is, the diameter of the ellipse, is increased within the second end surface 24b of the second flat wire 20b to fuse the second melted pool 30b with the first melted pool 30a . Specifically, whenever the laser beams return to their respective starting application positions (START indicated by the arrows in figure 13), the diameters of the ellipse being the application paths increase. Thus, the diameters of the first and second molten pools 30a, 30b also increase, so that, at the stage where the laser beams are respectively applied within the first end surface 24a of the first flat wire 20a and the second end surface 24b of the second flat wire 20b, the first molten pool 30a and the second molten pool 30b are melted in the vicinity of the
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    18/23 first and second side surfaces 23a, 23b.
    [071] As a result, the free space between the first side surface 23a and the second side surface 23b is filled with the first and second molten molten pools 30a, 30b. That is, at this stage, the laser beam is not applied to the first and second side surfaces 23a, 23b and the free space between the first side surface 23a and the second side surface 23b is filled with the melted first and second molten pools 30a, 30b. Thus, the laser beam is prevented from entering the free space between the first side surface 23a and the second side surface 23b.
    [072] Next, as shown in figure 14, the diameters of the laser beam application paths, that is, the diameters of the ellipses, are increased within the first end surface 24a of the first flat wire 20a and the second surface of end 24b of the second flat wire 20b, until the molten molten pool 30 grows to a desired size. Specifically, every time the laser beams return to their respective starting application positions (START indicated by the arrows in figure 14), the diameters of the ellipses being the application paths are increased. When the diameters of the ellipses reach a predetermined value, the application of the laser beams ends at their respective starting application positions (END indicated by the arrows in figure 14).
    [073] In the laser welding method for flat wires according to the second modality, unlike the laser welding method for flat wires according to the first modality, the laser beams are not applied on the first and second surfaces 23a, 23b even at the stage where the application of the laser beams ends. Furthermore, the free space between the first side surface 23a and the second side surface 23b is filled with the molten molten puddle 30. Thus, the laser beams can be prevented from entering the
    Petition 870170054618, of 7/31/2017, p. 51/70
    19/23 free space between the first side surface 23a and the second side surface 23b.
    [074] As described above, in the laser welding method for flat wires according to this modality, the laser beams are first applied in an arc shape respectively within the first end surface 24a of the first flat wire 20a and the second end surface 24b of the second flat wire 20b to form the first and second molten pools 30a, 30b. Next, the diameters of the laser beam application paths, that is, the diameters of the ellipses, are increased within the first end surface 24a of the first flat wire 20a and the second end surface 24b of the second flat wire 20b to melt the first melted puddle 30a and the second melted puddle 30b.
    [075] Thus, in the laser welding method for flat wires according to this modality, no laser beam is applied to the first and second side surfaces 23a, 23b throughout the entire welding process. Furthermore, the free space between the first side surface 23a and the second side surface 23b is filled with the melted puddle 30 (the melted puddle into which the first and second melted puddles 30a, 30b are melted). Compared with the laser welding method for flat wires according to the first modality, it is also possible to prevent the laser beam from entering the free space between the first side surface 23a and the second side surface 23b merging the first and second pools melted 30a, 30b. As a result, the adverse effects caused by the laser beam entering the free space between the side surfaces can be further reduced.
    [076] Thus, in the laser welding method for flat wires according to this modality, the first and second melted pools 30a, 30b are formed within the end surfaces of both flat wires and the first melted pool 30a and a second melted puddle 30b grow to melt. Then the
    Petition 870170054618, of 7/31/2017, p. 52/70
    20/23 free space between the first side surface 23a and the second side surface 23b is filled with the melted puddle 30 (the melted puddle into which the first and second melted puddles 30a, 30b are melted). It was confirmed that this method could prevent the laser beam from entering a free space of up to 0.30 mm. A free space of this value is twice as much as in the laser welding method for flat wires according to the first modality, which means that the second modality is more effective in preventing the entry of a laser beam in the free space between the side surfaces.
    [077] An example and comparative examples of the present invention will be described below. However, the present invention is not limited to the following example. Figure 15 is a table showing the test conditions and results of example 1 and comparative examples 1 and 2. In each of example 1 and comparative examples 1 and 2, flat wires (with a thickness of 2.147 mm and a width of the surface 4.0 mm end) having the end shape as shown in figure 8 were laser welded. A single mode fiber laser beam with a laser power of 2.0 kW and a beam diameter of 60 pm was used. The rate of movement of the laser beam along the application path was 750 mm / s. With only the application method varied between example 1 and comparative examples 1 and 2, these examples were compared in terms of drop appearance, splash generation, appearance of joint surfaces and dispersion of the laser beam across the free space between the joint surfaces (damage to the insulating films).
    [078] The top row of figure 15 shows the application methods of example 1 and comparative examples 1 and 2. In comparative example 1, the application path of the laser beam followed a path with sharp curves in a direction substantially perpendicular to the surfaces of the joint (side surfaces) in a central part of the pair of flat wires joined together. The region of application of
    Petition 870170054618, of 7/31/2017, p. 53/70
    21/23 comparative example 1 indicated by the hatch in figure 15 was 2.0 mm wide in the direction of the width of the flat wires and 1.0 mm thick in the direction of the thickness of the flat wires. The laser beam was applied from an upper left end to a right end of the application region shown in figure 15 and then returned to the upper left end to end the application (START / END in figure 15).
    [079] In comparative example 2, the application path of the laser beam followed a path with sharp curves in a direction substantially parallel to the joint surfaces (lateral surfaces) in a central part of the pair of joined flat wires. As in comparative example 1, the region of application of comparative example 2 indicated by the hatch in figure 15 was 2.0 mm wide in the direction of the width of the flat wires and 1.0 mm thick in the direction of the thickness of the flat wires. The laser beam was applied from a central point at an upper end to a lower end of the application region shown in figure 15 and then returned to the central point at the upper end to end the application (START / END in figure 15) .
    [080] The application path of the laser beam in example 1 was the elliptical path of the first modality that was described in detail using figure 2 to figure 5. As shown in figure 15, in the application region indicated by the hatch in figure 15 , the largest diameter of the longest elliptical path was 2.0 mm in the direction of the width of the flat wires and the smallest diameter of the longest elliptical path was 1.0 mm in the direction of the thickness of the flat wires. The laser beam was applied from a central point at an upper end of the application region shown in figure 15 and every time the laser beam returned to the central point at the upper end, the diameter of the ellipse was gradually increased. After the longest elliptical path was drawn, the application was terminated at the central point at the upper end (DEPART / END in figure 15).
    Petition 870170054618, of 7/31/2017, p. 54/70
    22/23 [081] The middle row of figure 15 shows a photograph of the appearance of the drops in example 1 and comparative examples 1 and 2. In comparative example 1, a disturbance in the drop and splash occurred. In comparative example 2, a large amount of splash was recognized. It is considered that a drop and splash disturbance tends to occur in comparative examples 1 and 2 because the melted puddle is disturbed at the return points of the trajectories. In example 1, no disturbance in the drop was observed and the amount of splash was significantly less than in comparative examples 1 and 2. A disturbance in the drop and splash is considered less likely to occur in example 1 because the elliptical path is not it has return points and, therefore, the laser beam can be applied constantly smoothly. The drop depth was 2.0 mm.
    [082] The bottom row of figure 15 shows photographs of the appearance of the joint surfaces (joined surfaces) in example 1 and comparative examples 1 and 2. In comparative examples 1 and 2, spark production was recognized at both ends of the surfaces. of the triangular joint. One possible cause is the concentration of heat at the return points. In example 1, no spark production was recognized. In example 1, the melted pool grows in the central part of the flat wires in the direction of the width while the laser beam is applied smoothly in an elliptical shape. This appears to be the reason why spark production at both ends can be avoided.
    [083] In comparative examples 1 and 2, the dispersion of the laser beam was recognized even when the free space between the joint surfaces was 0.1 mm. In example 1, in contrast, no dispersion of the laser beam was recognized for free spaces of up to 0.15 mm between the joint surfaces. In comparative examples 1 and 2, it is not possible to increase the melted pool and fill the free space between the joint surfaces with this melted pool before the beam
    Petition 870170054618, of 7/31/2017, p. 55/70
    23/23 of the laser pass over the joint surfaces. In example 1, in contrast, it is possible to fill the free space between the joint surfaces with the melted puddle before the laser beam passes over the joint surfaces. This appears to be the reason why the laser beam can be prevented from entering the free space between the joint surfaces.
    [084] The present invention is not limited to the above modalities, but can be appropriately changed within the scope of the goal of the invention.
    Petition 870170054618, of 7/31/2017, p. 56/70
    1/3
    权利要求:
    Claims (11)
    [1]
    1. Laser welding method for flat wires, in which a first side surface (23a) is joined to a first end of a first flat wire (20a) coated with a first insulating film (21a), the first side surface (23a) ) being separated from the first insulating film (21a), and a second side surface (23b) at a second end of a second flat wire (20b) coated with a second insulating film (21b), the second side surface (23b) being separated of the second insulating film (21b), and a laser beam is applied to a first end surface (24a) of the first flat wire (20a) and a second end surface (24b) of the second flat wire (20b) to join by welds the first side surface (23a) and the second side surface (23b), the laser welding method CHARACTERIZED by the fact that it comprises:
    apply the laser beam in an arc shape within the first end surface (24a) to form a melted puddle (30) and apply the laser beam within the first end surface (24a) while gradually increasing the diameter of a path arc-shaped laser beam to allow the melted pool (30) to reach the first side surface (23a) and the second side surface (23b).
    [2]
    2. Laser welding method according to claim 1, CHARACTERIZED by the fact that the shape of the arc is a circular shape or an elliptical shape.
    [3]
    3. Laser welding method, according to claim 1, CHARACTERIZED by the fact that the shape of the arc is a rectangular shape.
    [4]
    4. Laser welding method, according to claim 1, CHARACTERIZED by the fact that the shape of the arc is a spiral shape.
    [5]
    5. Laser welding method according to claim 1,
    Petition 870170054618, of 7/31/2017, p. 57/70
    2/3
    CHARACTERIZED by the fact that the shape of the arc is an elliptical shape and the major geometric axis of the ellipse is parallel to the first lateral surface (23a) and the second lateral surface (23b).
    [6]
    6. Laser welding method according to any one of claims 1 to 5, CHARACTERIZED by the fact that, on the first end surface (24a), the laser beam is applied to only one region of the first end surface ( 24a) which is located on the side of the first lateral surface (23a) in relation to a starting position of application of the laser beam.
    [7]
    7. Laser welding method according to any one of claims 1 to 6, CHARACTERIZED by the fact that the laser beam is applied to the second end surface (24b), as the diameter of the arc-shaped path of the laser beam gradually increases.
    [8]
    8. Laser welding method according to any one of claims 1 to 5, CHARACTERIZED by the fact that it still comprises:
    apply another laser beam in an arc shape within the second end surface (24b) to form another molten pool and apply the other laser beam within the second end surface (24b) while gradually increasing the diameter of a shaped path arc of the other laser beam to fuse the melted pool and the other melted pool.
    [9]
    9. Laser welding method according to claim 8, CHARACTERIZED by the fact that on the first end surface (24a), the laser beam is applied to only a region of the first end surface (24a) that is located on one side of the first side surface (23a) in relation to a starting position of applying the laser beam, and on the second end surface (24b), the other laser beam is applied to only one region of the second end surface (24b) that is
    Petition 870170054618, of 7/31/2017, p. 58/70
    3/3 located on one side of the second side surface (23b) in relation to an application start position of the other laser beam.
    [10]
    10. Laser welding method according to claim 8 or 9, CHARACTERIZED by the fact that the laser beam is applied to the second end surface (24b), as the diameter of the arc-shaped path of the beam of the laser gradually increases and the other laser beam is applied to the first end surface (24a), as the diameter of the arc-shaped path of the other laser beam gradually increases.
    [11]
    11. Laser welding method according to claim 8 or 9, CHARACTERIZED by the fact that the laser beam is applied to only the first end surface (24a) and the other laser beam is applied to only the second end surface (24b).
    Petition 870170054618, of 7/31/2017, p. 59/70
    1/10
    THE
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    同族专利:
    公开号 | 公开日
    ES2711212T3|2019-04-30|
    EP3292940A1|2018-03-14|
    US20180036836A1|2018-02-08|
    MX2017009876A|2018-09-18|
    RU2666201C1|2018-09-06|
    CN107671420B|2019-08-06|
    AU2017208275B2|2018-11-08|
    MX367809B|2019-09-06|
    PH12017050035B1|2018-08-06|
    US10717153B2|2020-07-21|
    JP6390672B2|2018-09-19|
    KR20180015083A|2018-02-12|
    KR101984803B1|2019-05-31|
    JP2018020340A|2018-02-08|
    EP3292940B1|2019-01-09|
    PH12017050035A1|2018-08-06|
    AU2017208275A1|2018-02-22|
    CN107671420A|2018-02-09|
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    法律状态:
    2018-02-27| B03A| Publication of a patent application or of a certificate of addition of invention [chapter 3.1 patent gazette]|
    2021-07-06| B06W| Patent application suspended after preliminary examination (for patents with searches from other patent authorities) [chapter 6.23 patent gazette]|
    优先权:
    申请号 | 申请日 | 专利标题
    JP2016-152242|2016-08-02|
    JP2016152242A|JP6390672B2|2016-08-02|2016-08-02|Laser welding method for flat wire|
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