Laminated iron core, and manufacturing device and method thereof

Abstract

[Problem] To ensure the necessary joining strength between iron core thin plates but suppress excessive heat accumulation at weld parts during the production of a laminated iron core. [Solution] A production method for a laminated iron core according to the present invention involves successively forming a plurality of spot-shaped weld parts 59 at a plurality of layered iron core thin plates 11 so as to join the plurality of iron core thin plates 11. The production method includes a first welding step for forming first weld parts that are a plurality of the weld parts 59 at a first iron core thin plate group that comprises a portion of the plurality of iron core thin plates 11 at a first pitch in the layering direction and, after the first welding step, a second welding step for forming second weld parts that are a plurality of the weld parts 59 at a second iron core thin plate group that is adjacent to the first iron core thin plate group and comprises a portion of the plurality of iron core thin plates 11 at a second pitch in the layering direction, the second pitch being greater than the first pitch.

Description

[Technical Field]

[0001] The present invention relates to a laminated core used in a motor core or the like, and to an apparatus and method for manufacturing the same. [Background technology]

[0002] Conventionally, in the manufacture of laminated cores, each thin core plate (thin steel plate) that makes up the laminated core is punched out in a predetermined shape from electromagnetic steel sheet material, and then a predetermined number of sheets are stacked and joined together.

[0003] One known method for joining thin iron core plates together is to join multiple stacked thin iron core plates by welding (laser welding, etc.).As a manufacturing method of a laminated iron core using welding, for example, in order to ensure sufficient joining strength between the thin iron core plates, a laser beam spot is sequentially irradiated onto the overlapping seams or plate thickness portions of the stacked steel plates (thin iron core plates), and the diameter of the laser beam spot is set to more than twice the thickness of the steel plates, thereby sequentially welding and joining three or more adjacent steel plates together (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 9-149605 Summary of the Invention [Problem to be solved by the invention]

[0005] In the method of continuously forming multiple spot-shaped welds using a laser or the like, as in Patent Document 1, the bonding strength between the iron core thin plates by welding can be improved by setting the pitch (spacing) of adjacent welds as small as possible (i.e., setting the overlapping area of ​​adjacent welds as large as possible).

[0006] On the other hand, if the pitch of adjacent welds is set small and welding is performed continuously, the amount of heat stored in the welds (i.e., the amount of melting in the welds) gradually increases as the welding progresses. Therefore, as a result of extensive research, the inventors of the present application have found that such an increase in the amount of heat stored in the welds can result in an excessive increase in the amount of shrinkage (tensile residual stress) when the temperature drops after welding, particularly in welds located closer to the center in the lamination direction of the laminated core. Such an increase in the amount of shrinkage in the welds can cause deformation of the laminated core.

[0007] In view of the above background, an object of the present invention is to suppress excessive heat accumulation in welded portions while ensuring the necessary bonding strength between thin core plates when manufacturing a laminated core by welding. [Means for solving the problem]

[0008] In a first aspect of the present invention, there is provided a method for manufacturing a laminated core, in which a plurality of stacked core thin plates are joined together by continuously forming a plurality of spot-shaped welds on the stacked core thin plates, the method including: a first welding process for forming first welds that constitute the plurality of welds at a first pitch in the stacking direction on a first core thin plate group consisting of a portion of the plurality of core thin plates; and a second welding process, after the first welding process, for forming second welds that constitute the plurality of welds at a second pitch in the stacking direction on a second core thin plate group consisting of a portion of the plurality of core thin plates adjacent to the first core thin plate group, wherein the second pitch is greater than the first pitch.

[0009] This makes it possible to suppress excessive heat accumulation in the welded portion while ensuring the necessary bonding strength between the thin core plates when manufacturing a laminated core by welding.

[0010] In a second aspect of the present invention, after the second welding step, it is preferable to further include a third welding step of forming third welds constituting the plurality of welds in a third iron core thin plate group consisting of a portion of the plurality of iron core thin plates adjacent to the second iron core thin plate group at a third pitch in the stacking direction that is different from the second pitch.

[0011] This makes it possible to more stably ensure the necessary bonding strength between the thin core plates when manufacturing a laminated core by welding, while suppressing excessive heat accumulation in the welded portion.

[0012] In the third aspect of the present invention, the third pitch may be larger than the second pitch.

[0013] This makes it possible to more stably prevent excessive heat accumulation in the welded portion depending on the thermal conductivity of the material forming the iron core thin plate.

[0014] In the fourth aspect of the present invention, the third pitch may be smaller than the second pitch.

[0015] This makes it possible to more stably ensure the necessary bonding strength between the thin core plates in accordance with the thermal conductivity of the material forming the thin core plates.

[0016] In the fifth aspect of the present invention, the third pitch may be the same as the first pitch.

[0017] This makes it possible to stably ensure the necessary bonding strength between the thin core plates with a simple configuration, depending on the thermal conductivity of the material that forms the thin core plates.

[0018] In the sixth aspect of the present invention, the first welding step, the second welding step, and the third welding step may be repeatedly performed.

[0019] This makes it possible to more appropriately prevent excessive heat accumulation in the welded portion while more appropriately ensuring the necessary bonding strength between the thin core plates when manufacturing a laminated core by welding.

[0020] In a seventh aspect of the present invention, the first welding process may further include a temperature measurement process for sequentially measuring the temperature of the first welded portion, and the timing for starting the second welding process may be determined based on the temperature of the first welded portion.

[0021] According to this, when manufacturing a laminated core by welding, the pitch of the welded portions can be appropriately changed depending on the temperature of the welded portions.

[0022] In an eighth aspect of the present invention, the laminated core is composed of N (N is an integer) of the core thin plates, and the pitch at which the welds are formed is changed so that at least one weld is formed in the Nth core thin plate.

[0023] This makes it possible to reliably join the Nth thin core plate (that is, the last thin core plate to be welded) regardless of changes in the pitch of the welded portions in one laminated core.

[0024] In a ninth aspect of the present invention, there is provided a laminated core manufacturing apparatus that joins a plurality of stacked core thin plates by continuously forming a plurality of spot-shaped welds on the plurality of stacked core thin plates, the apparatus comprising: a laser irradiation unit that forms the plurality of welds by irradiating the plurality of core thin plates with spot-shaped laser light; and a laser controller that controls the irradiation of the laser light by the laser irradiation unit, wherein the laser irradiation unit, under the control of the laser controller, forms first welds that constitute the plurality of welds on a first core thin plate group consisting of a portion of the plurality of core thin plates at a first pitch in the stacking direction, and forms second welds that constitute the plurality of welds on a second core thin plate group consisting of a portion of the plurality of core thin plates adjacent to the first core thin plate group at a second pitch in the stacking direction, the second pitch being greater than the first pitch.

[0025] This makes it possible to suppress excessive heat accumulation in the welded portion while ensuring the necessary bonding strength between the thin core plates when manufacturing a laminated core by welding.

[0026] In a tenth aspect of the present invention, the manufacturing method further includes a progressive die that sequentially punches out the plurality of iron core thin plates from an intermittently transported strip-shaped thin steel plate and stacks the plurality of iron core thin plates, and the laser irradiation unit is preferably arranged in the progressive die so as to be able to irradiate the laser light inside a core holding member that holds the iron core thin plates whose outline has been punched out from the strip-shaped thin steel plate.

[0027] This allows a plurality of thin iron core plates that have been punched out by a progressive die and stacked together to be stably joined by welding.

[0028] In an eleventh aspect of the present invention, the laser irradiation unit may, under the control of the laser controller, form third welds constituting the plurality of welds in a third iron core thin plate group consisting of a portion of the plurality of iron core thin plates adjacent to the second iron core thin plate group at a third pitch in the stacking direction that is different from the second pitch.

[0029] This makes it possible to more stably ensure the necessary bonding strength between the thin core plates when manufacturing a laminated core by welding, while suppressing excessive heat accumulation in the welded portion.

[0030] In the twelfth aspect of the present invention, the laser irradiation unit may repeatedly form the first welded portion, the second welded portion, and the third welded portion.

[0031] This makes it possible to more stably prevent excessive heat accumulation in the welded portion while more stably ensuring the necessary bonding strength between the thin core plates when manufacturing a laminated core by welding.

[0032] In a thirteenth aspect of the present invention, the laser controller may further include a temperature sensor that sequentially measures the temperature of the first welded portion, and the laser controller may determine the timing for starting to form the second welded portion based on the temperature of the first welded portion.

[0033] According to this, when manufacturing a laminated core by welding, the pitch of the welded portions can be appropriately changed depending on the temperature of the welded portions.

[0034] In a fourteenth aspect of the present invention, the laminated core may be configured by N (N is an integer) of the core thin plates, and at least one of the welds may be formed in the Nth core thin plate.

[0035] This makes it possible to reliably join the Nth thin core plate (that is, the last thin core plate to be welded) regardless of changes in the pitch of the welded portions in one laminated core.

[0036] In a fifteenth aspect of the present invention, there is provided a laminated core in which a plurality of stacked core thin plates are joined together by a plurality of spot-shaped welds formed continuously on the stacked core thin plates, wherein the plurality of welds include first welds formed at a first pitch in the stacking direction of the plurality of core thin plates on a first group of core thin plates consisting of a portion of the plurality of core thin plates, and second welds formed at a second pitch in the stacking direction on a second group of core thin plates consisting of a portion of the plurality of core thin plates adjacent to the first group of core thin plates, and the second pitch is larger than the first pitch.

[0037] This allows the necessary bonding strength between the core sheets to be secured while preventing excessive heat accumulation in the welds during the manufacturing of the laminated core by welding. As a result, a laminated core can be realized that has the necessary bonding strength between the core sheets and reduces the amount of shrinkage in the welds (i.e., improved manufacturing precision). [Effects of the Invention]

[0038] Thus, according to the present invention, when manufacturing a laminated core by welding, it is possible to prevent excessive heat accumulation in the welded portion while ensuring the necessary bonding strength between the thin core plates. [Brief explanation of the drawings]

[0039] [Figure 1] FIG. 1 is a diagram showing a main part of a laminated core manufacturing device according to an embodiment. [Figure 2] FIG. 1 is a plan view showing an example of a welded portion in a laminated core; [Figure 3] FIG. 10 is an explanatory diagram showing an example of the pitch of welds formed in a laminated core. [Figure 4] FIG. 10 is an explanatory diagram showing an example of a weld formed at an end of a laminated core. [Figure 5] FIG. 10 is an explanatory diagram showing an example in which a laminated core has a plurality of regions with different weld pitches. [Figure 6] FIG. 6 is an explanatory diagram showing an example of a combination of weld pitches in the laminated core shown in FIG. 5. [Figure 7] FIG. 2 is a diagram showing a first modified example of the laminated core manufacturing apparatus shown in FIG. [Figure 8] FIG. 2 is a diagram showing a second modified example of the laminated core manufacturing apparatus shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0040] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0041] FIG. 1 is a diagram showing the main parts of a laminated iron core manufacturing apparatus 1 according to an embodiment of the present invention.

[0042] As shown in FIG. 1, a laminated core manufacturing apparatus 1 includes a progressive die 3 and a welding device 5 attached thereto.

[0043] The progressive die 3 performs metal press processing on a hoop material W (coil-shaped metal material) made of electromagnetic steel sheets to manufacture a laminated iron core 13 made by stacking a plurality of iron core thin plates 11 (thin core pieces). The progressive die 3 has an upper die 15 that is provided so as to be able to reciprocate in the vertical direction, and a lower die 16 that is fixed to a holder (not shown).

[0044] The upper die 15 has a plurality of punches for punching out the hoop material W (only punch 19 for punching out the outer shape of the iron core thin plate 11 is shown in FIG. 1), and a punch holder 21 for holding these punches. The upper die 15 also has a plurality of guide posts (only guide post 23 is shown here) extending up and down to guide the raising and lowering movement of the punch holder 21, and a stripper plate 25 that is slidably supported by a stripper guide (not shown) and separates the hoop material W from the punches after punching.

[0045] Although detailed description will be omitted, the progressive die 3 punches out internal shapes such as pilot holes (positioning holes), slots, and teeth as needed from the hoop material W. This allows the shapes of the core sheets 11 that make up the laminated core 13 to be continuously formed in the hoop material W before the outer shape is punched out.

[0046] The upper part of upper die 15 is fixed to a slide part (not shown) that moves reciprocally in the up and down direction (for example, moves up and down with a stroke of about 25 mm to 35 mm). In the slide part, the rotational motion of crankshaft 29 driven by upper die driving motor 27 is converted into the up and down motion of upper die 15 via a connecting rod (not shown). In addition, the slide part is provided with an encoder 31 that detects the rotation phase of crankshaft 29 (the rotation angle from a reference rotation position of crankshaft 29) and generates an encoder signal (hereinafter referred to as a "synchronization signal") that indicates the detection result.

[0047] The lower die 16 includes a die 33, a die plate 34, a die holder 35, and a squeeze ring 36 (an iron core holding member).

[0048] The die 33 has a generally circular punching hole into which a generally cylindrical punch 19 is inserted. The punch 19 cooperates with the die 33 to punch out the outline of the core sheet 11. The periphery of the die 33 is held by a die plate 34. The lower surface of the die plate 34 is supported by a die holder 35.

[0049] The squeeze ring 36 is connected to the lower end of the die 33 and applies lateral pressure (clamping force) to the iron core sheets 11 stacked therein. The inner diameter of the squeeze ring 36 is set to be the same as the inner diameter of the die 33 (set to be the same as the inner diameter, or set to be slightly smaller or slightly larger than the inner diameter), and the squeeze ring 36 moves the iron core sheets 11 punched into the die 33 by the punch 19 successively downward while holding them with a predetermined lateral pressure.

[0050] The core thin plates 11 whose outer shape has been punched out from the hoop material W are successively pushed into the die 33 by the punch 19 so as to overlap the previously punched core thin plates 11 in the die 33. As a result, the core thin plates 11 in the die 33 and squeeze ring 36 move intermittently to the discharge side (here, downward) by an amount roughly equivalent to the thickness of the core thin plate 11 each time a new core thin plate 11 is punched out.

[0051] In the progressive die 3, the core holding member for holding the punched core thin plates 11 is not limited to the squeeze ring 36, and any roughly cylindrical member can be used as long as it can accommodate at least a plurality of core thin plates 11 and be used to stack them. The core holding member may not only be one that applies lateral pressure to the stacked core thin plates 11, but also one that uses a cylindrical hole (guide hole) to align the core pieces. Furthermore, the hole shape of the core holding member is not limited to a circle, and various shapes such as a square, sector, trapezoid, or T-shape can be used to match the shape of the core thin plates 11.

[0052] Furthermore, before performing laser welding using the welding device 5, it is also possible to crimp and join adjacent core thin plates 11 one to another by forming crimping recesses and protrusions on the adjacent core thin plates 11 in the progressive die 3, or to join adjacent core thin plates 11 one to another by applying adhesive to at least one of the adjacent core thin plates 11.

[0053] The welding device 5 includes a laser irradiation unit 41, an irradiation adjustment unit 42, a laser oscillator 43, and a laser controller 44.

[0054] The laser irradiation unit 41 is provided so as to be able to irradiate the squeeze ring 36 with laser light through an opening 46 that opens in the side (peripheral wall) of the squeeze ring 36. The laser irradiation unit 41 includes a condenser lens (not shown) that condenses the laser light. The condensed laser light is irradiated at a predetermined position on the peripheral surface of the iron core thin plates 11 stacked in the squeeze ring 36. The irradiated laser light has a predetermined spot shape on the peripheral surface of the iron core thin plates 11. In this embodiment, the spot shape of the laser light is approximately circular, but is not limited to this and may be other shapes (e.g., elliptical or rectangular). In addition, the laser irradiation unit 41 can spray a shielding gas (argon, helium, etc.) from its tip against the welded portion of the iron core thin plates 11.

[0055] The laser irradiation units 41 are provided according to the number of welding locations in the laminated core 13. For example, in the example of FIG. 2 described later, laser irradiation units 41 are provided to correspond to four welding locations, respectively. Furthermore, the irradiation of laser light by the laser irradiation units 41 is not limited to the iron core thin sheets 11 stacked inside the squeeze ring 36, but can also be performed on iron core thin sheets 11 stacked inside the die 33 or any other substantially cylindrical member. In this case, the installation position of the laser irradiation unit 41 can be changed as appropriate to the vicinity of the irradiation position for the iron core thin sheets 11 (for example, the die 33 or the die plate 34).

[0056] The irradiation adjustment unit 42 holds the laser irradiation unit 41 in a displaceable manner, thereby changing the irradiation angle of the laser light emitted from the laser irradiation unit 41. For example, the initial position of the laser irradiation unit 41 can be set so that the irradiation direction of the laser light is horizontal (a direction perpendicular to the stacking direction of the iron core thin plates 11). The irradiation adjustment unit 42 can change the irradiation angle of the laser light by tilting the tip of the laser irradiation unit 41, in which a light outlet is formed, up and down using a rotation axis perpendicular to both the stacking direction of the iron core thin plates 11 and the irradiation direction of the laser light.

[0057] Furthermore, the irradiation adjustment unit 42 can move the laser irradiation unit 41 in the horizontal direction, thereby changing the focal position of the laser light relative to the peripheral surface of the iron core thin plates 11 and changing the size of the spot shape of the laser light (i.e., the diameter of the laser light on the surface of the plurality of stacked iron core thin plates 11).

[0058] The laser oscillator 43 is connected to the laser irradiation unit 41 via an optical cable 47, so that the oscillated laser light can be introduced into the laser irradiation unit 41. As the laser oscillator 43, a YAG laser oscillator, a CO2 laser oscillator, a fiber laser oscillator, or the like can be appropriately adopted.

[0059] The laser controller 44 is connected to the laser oscillator 43 and controls the output and oscillation mode of the laser beam from the laser oscillator 43 by sending power and control signals to the laser oscillator 43. This controls the irradiation of the laser beam from the laser irradiation unit 41. The laser oscillator 43 can oscillate the laser beam in a pulsed manner by setting the irradiation time relatively short, or in a continuous manner by setting the irradiation time relatively long. The laser oscillator 43 can also pause the irradiation of the laser beam from the laser irradiation unit 41 as necessary.

[0060] Furthermore, the laser controller 44 is connected to, for example, the encoder 31 of the progressive die 3, and receives a synchronization signal from the encoder 31. The laser controller 44 adjusts the timing of irradiating the thin iron core plate 11 with the laser light based on the synchronization signal (the timing of punching out the thin iron core plate 11, and ultimately the timing of the movement (lowering) of the thin iron core plate 11 in the squeeze ring 36), and can also change the output and oscillation mode of the laser light.

[0061] FIG. 2 is a plan view showing an example of a welded portion 59 in the laminated core 13. As shown in FIG.

[0062] 2 shows an example in which the laminated core 13 is formed as a rotor (armature). The laminated core 13 is composed of a central portion 53 having an axial hole 51 formed at its axis, into which a motor shaft (not shown) is fitted, and four teeth 54 projecting radially from the central portion 53 at equal intervals in the circumferential direction. The outer end of each tooth 54 is provided with magnetic pole portions 55 that extend circumferentially on both sides and face a stator (not shown).

[0063] Welds 59 are formed at multiple locations on the outer peripheral surface of the laminated core 13 at predetermined intervals in the circumferential direction in a plan view. Each weld 59 is a portion (weld mark) formed by heating and melting the laminated core 13 (thin core sheets 11) by irradiating it with laser light. Here, a weld 59 is formed on the outer peripheral surface of each magnetic pole portion 55 of each tooth 54. Each weld 59 is formed continuously (i.e., as part of a weld mark including a series of welds 59) so as to be connected in the stacking direction of the thin core sheets 11 in the laminated core 13 (the direction perpendicular to the paper surface of FIG. 2).

[0064] The pitch of the welds 59 at the multiple circumferential locations shown in FIG. 2 is the same. That is, the pitch of the multiple welds 59 formed consecutively in the stacking direction at the multiple locations is changed in the same manner (or simultaneously) at the same position in the stacking direction. However, the multiple welds 59 at the multiple locations may be formed at different pitches at the same position in the stacking direction. The shape of the core sheets 11 constituting the laminated core 13 is not limited to the example shown in FIG. 2, and various shapes such as rectangular, sectorial, trapezoidal, T-shaped, and U-shaped can be used. The number and positions of the welds 59 in the laminated core 13 can be changed as needed.

[0065] Fig. 3 is an explanatory diagram showing an example of the pitch of welds 59 formed on the laminated core 13. Fig. 4 is an explanatory diagram showing an example of welds 59 formed on the end of the laminated core 13. For ease of explanation, Figs. 3 and 4 schematically show the welds 59 and their surroundings on the laminated core 13 (plurality of laminated core thin plates 11).

[0066] 3(A)-(C), welding device 5 allows for changing the pitch of welds 59. The pitch of welds 59 corresponds to the distance between the centers of adjacent welds 59 (or the geometric centers of their outer shapes). The pitch of welds 59 can be changed by at least one of changing the irradiation direction or irradiation position of the laser light from laser irradiation unit 41, changing the output of the laser light from laser oscillator 43 (including pausing), and changing the oscillation mode of the laser light from laser oscillator 43.

[0067] The shape of the welds 59 (roughly corresponding to the shape of the spot-like laser beam) is substantially circular. The outer diameter of the welds 59 (particularly the diameter in the stacking direction of the iron core thin plates 11) is set to be more than three times but less than four times the thickness of each iron core thin plate 11 in the stacking direction (the vertical direction in FIG. 3). Each weld 59 can be formed on four or five adjacent iron core thin plates 11. Here, the welds 59 are formed to join four iron core thin plates 11, taking into account the strength of the bond formed by each weld 59. However, in the laminated iron core manufacturing apparatus 1, the amount of heat stored in the welds may be adjusted by changing the beam diameter (diameter of the light beam) of the laser beam without changing the pitch of the welds 59. For example, the welds 59 can be formed at the boundary between adjacent (paired) iron core thin plates 11, and the size of the spot shape of the laser beam can be changed (e.g., the diameter can be selectively changed to 0.5, 1, or 1.5 times the thickness of the iron core thin plates 11).

[0068] 3(A)-(C), the center of each weld 59 is located at the boundary between adjacent core thin plates 11. However, the relative position of the weld 59 with respect to the core thin plates 11 can be changed as appropriate, taking into consideration the overlap between each weld 59 and the multiple core thin plates 11 to which each weld 59 is to be joined. For example, the center of the weld 59 may be located at the center of the core thin plates 11 in the thickness direction.

[0069] 3(A) shows an example in which the pitch P1 of the welds 59 is set to the same size as the thickness of the iron core thin plates 11. As described above, even if the laser light irradiation position of the iron core thin plates 11 stacked within the squeeze ring 36 is fixed, the iron core thin plates 11 move intermittently in a direction approximately perpendicular to the direction of laser light irradiation each time each iron core thin plate is punched (i.e., by the thickness of one sheet). Therefore, even if the laser light is continuously irradiated from the laser irradiation unit 41, the influence of irradiation when the iron core thin plates 11 are stationary becomes large, and the welds 59 can be formed at the pitch P1 as shown in FIG. 3(A).

[0070] 3(B) shows an example in which the pitch P2 of the welded portions 59 is set to twice the thickness of the iron core thin plate 11. FIG. 3(C) shows an example in which the pitch P3 of the welded portions 59 is set to three times the thickness of the iron core thin plate 11. These pitches can be achieved by at least one of changing the output (including pauses) of the laser light from the laser oscillator 43 and changing the oscillation pattern of the laser light from the laser oscillator 43.

[0071] The size of the outer diameter of the welds 59 and the pitch applicable to the welds 59 are not limited to the examples shown in Figures 3(A)-(C) as long as the required bonding strength between the core thin plates 11 is ensured. For example, it is possible to adopt a larger pitch by setting a larger outer diameter of the welds 59. Furthermore, the pitch of the welds 59 is not limited to an integer multiple of the thickness of the core thin plates 11, and can be set to any size.

[0072] Furthermore, for example, when the pitch P1 of the welds 59 is changed to pitch P2, the weld 59 located at the rearmost (here, the top) of the multiple welds 59 formed at pitch P1 becomes the weld 59 located at the frontmost (here, the bottom) of the multiple welds 59 formed at pitch P2. However, the pitch of the welds located at the boundary between pitch P1 and pitch P2 of the welds 59 may be a pitch other than pitch P1 or P2 (e.g., a pitch larger than pitch P1 but smaller than pitch P2, or a pitch smaller than pitch P1). More specifically, the weld 59 located at the rearmost of the multiple welds 59 formed at pitch P1 and the weld 59 located at the frontmost of the multiple welds 59 formed at pitch P2 may be separate welds 59, and the pitch between them may be a pitch other than pitch P1 or P2. This makes it possible to adjust the relative position of each weld 9 formed at the changed pitch (here, pitch P2) with respect to each iron core sheet 11. This configuration can be similarly applied to changes in pitches other than the pitches P1 and P2.

[0073] Furthermore, when a pitch larger than the thickness of the core sheets 11 is used, such as pitch P2 or pitch P3, it may not be possible to form weld 59 up to the rearmost core sheet 11 in the laminated core 13 (here, the core sheet 11 located in the top layer of the laminated core 13 or the adjacent core sheet 11) at the same pitch. In other words, the weld 59 may not be formed at the rearmost part of the laminated core 13, or if the weld 59 is formed, it may extend beyond the end face of the laminated core 13.

[0074] Therefore, when a pitch larger than the thickness of the iron core thin plates 11 is used, the welding device 5 can change the pitch for the rearmost iron core thin plates 11 of the laminated iron core 13 as needed.

[0075] 4 shows an example in which the pitch P3 of the welds 59 is changed to a smaller pitch P1. When the laminated core 13 is made up of N (N is an integer) iron core thin plates 11, the pitch at which the welds 59A are formed is changed so that at least one weld is formed in the Nth iron core thin plate 11A, which is welded last.

[0076] More specifically, in welding with pitch P3 shown in Fig. 4, the Nth (top layer in Fig. 4) iron core thin plate 11A cannot be welded as is because the laser light for forming the corresponding weld 59 extends beyond the upper edge of iron core thin plate 11A. Therefore, for the Nth iron core thin plate 11A, the pitch is changed from P3 to P1 so that weld 59A is formed on the Nth iron core thin plate 11A.

[0077] 4 shows an example in which the pitch of only the last welded portion 59 formed is changed, but this is not limiting, and the pitch of multiple welded portions 59 formed on one or more of the rearmost core thin plates 11 may also be changed. Furthermore, the change in the pitch of the welded portions 59 is not limited to a change from pitch P3 to pitch P1, as long as at least the last welded core thin plate 11A is appropriately joined to the adjacent core thin plate 11.

[0078] Furthermore, such a change in pitch need only be a change to a pitch smaller than the previous pitch, and is not limited to a change to pitch P1. However, changing to pitch P1 (a pitch the same size as the thickness of core thin plates 11) has the advantage of increasing the bonding strength of the ends of laminated core 13 and stably maintaining the strength of the entire laminated core 13.

[0079] Fig. 5 is an explanatory diagram showing an example of a laminated core 13 having a plurality of regions with different pitches of welded portions 59. Fig. 6 is an explanatory diagram showing an example of combinations of pitches of welded portions 59 in the laminated core shown in Fig. 5.

[0080] 5, the multiple pitches of the welded portions 59 described above can be applied to multiple regions (here, first to third regions R1-R3) divided in the lamination direction of the laminated core 13. The first to third regions R1-R3 each include a block made up of multiple core thin plates 11 (first to third core thin plate groups).

[0081] In the example of FIG. 5, region R1 constitutes the lower part of the laminated core 13 (including the core thin plate 11 in the bottom layer where welding to one laminated core 13 begins). Region R2 constitutes the middle part of the laminated core 13. Region R3 constitutes the upper part of the laminated core 13 (including the core thin plate 11 in the top layer where welding to one laminated core 13 ends). However, the number of core thin plates 11 that constitute regions R1-R3 is not necessarily set in advance (before welding begins), but can be set as a result of changing the pitch of the welds 59.

[0082] 6, welding pattern 1 is an example in which a small pitch P1 (first pitch in welding pattern 1), a medium pitch P2 (second pitch in welding pattern 1), and a large pitch P3 (third pitch in welding pattern 1) are applied to regions R1, R2, and R3, respectively. That is, in welding pattern 1, the pitch of welds 59 gradually increases in the order of regions R1, R2, and R3. That is, in welding pattern 1, three welding processes (first to third welding processes) are performed in which the pitch of welds 59 differs from one another.

[0083] In this welding pattern 1, in region R1 with a relatively small pitch, the amount of heat stored in welded portion 59 gradually increases (heat dissipation becomes more difficult) as welding progresses. However, in welding pattern 1, by increasing the pitch in region R2 (here, changing from a small pitch to a medium pitch) before such heat storage becomes excessive, it is possible to suppress the subsequent increase in the amount of heat stored in welded portion 59.

[0084] Furthermore, in welding pattern 1, the amount of heat stored in welded portion 59 also gradually increases as welding progresses in region R2. However, in welding pattern 1, by increasing the pitch in region R3 (here, changing from a medium pitch to a large pitch) before such heat storage becomes excessive, it is possible to suppress the subsequent increase in the amount of heat stored in welded portion 59.

[0085] Welding pattern 2 is an example in which a medium pitch P2 (first pitch in welding pattern 2) and a large pitch P3 (second pitch in welding pattern 2) are applied to region R1 and regions R2 and R3, respectively. That is, in welding pattern 2, the pitch of welds 59 increases in the transition from region R1 to region R2, and then the same pitch as region R2 is applied to the subsequent region R3. That is, in welding pattern 2, two welding processes (first and second welding processes) in which the pitch of welds 59 is different from each other are performed.

[0086] In this welding pattern 2, even if the thermal conductivity of the material of the core thin plates 11 is relatively low, by applying pitch P2 (medium pitch) to region R1, heat accumulation in each weld 59 can be suppressed.

[0087] Furthermore, in welding pattern 2, as welding in region R1 progresses, the amount of heat stored in welded portion 59 gradually increases. However, in welding pattern 2, by increasing the pitch in region R2 (here, changing from a medium pitch to a large pitch) before such heat storage becomes excessive, it is possible to suppress the subsequent increase in the amount of heat stored in welded portion 59.

[0088] In addition, if the thermal conductivity of the material of the iron core thin plate 11 is higher than that in the case of welding pattern 1, a small pitch P1 (first pitch in welding pattern 3) and a medium pitch P2 (second pitch in welding pattern 3) may be applied to region R1 and regions R2 and R3, respectively, as shown in welding pattern 3.

[0089] Furthermore, in region R3 of welding pattern 3, the same pitch as in region R2 is applied, but if the amount of heat stored in welded portion 59 in region R2 can be suppressed, the pitch of welded portion 59 can be reduced again (here, changed to a larger pitch) as shown in welding pattern 4, thereby increasing the bonding strength of core thin plates 11 in region R3 (end of laminated core 13). Such a pitch reduction can also be adopted in region R3 of welding pattern 2.

[0090] The regions in the laminated core 13 where the pitch of the welded portions 59 is changed are not limited to the regions R1-R3 illustrated in FIG. 5. The number of such regions and their sizes (i.e., the number of core sheets 11 constituting the regions) can be changed as appropriate. Furthermore, the welding patterns are not limited to those illustrated in FIG. 6. For example, any of the welding patterns 1-4 may be repeatedly performed in one laminated core 13. In this case, for example, in welding pattern 1, the region R1-R3 may be set again after (above) the region R1-R3 illustrated in FIG. 5 (more precisely, the region R1-R3 in which the number of constituting the region R1-R3 is reduced). Furthermore, one or more of the above-described welding patterns 1-4 may be combined and performed in one laminated core 13.

[0091] In such laminated core 13, the required bond strength between the core thin plates 11 is ensured during manufacturing by welding, and excessive heat accumulation in welded joints 59 is suppressed. As a result, laminated core 13 has the required bond strength between the core thin plates 11, and the amount of shrinkage of welded joints 59 is suppressed (i.e., manufacturing precision is improved).

[0092] 7 and 8 are diagrams showing first and second modified examples of the laminated iron core manufacturing apparatus 1 shown in Fig. 1. In Fig. 7 and Fig. 8, the same components as those in the manufacturing apparatus 1 shown in Fig. 1 are given the same reference numerals. Furthermore, with regard to the first and second modified examples, matters not specifically mentioned below are the same as those in the manufacturing apparatus 1 shown in Fig. 1.

[0093] 7, in the laminated core manufacturing apparatus 1 according to the first modification, a temperature sensor 61 capable of measuring the temperature of a welded portion 59 immediately after it has been welded (formed) is provided in the welding device 5. The laser controller 44 is connected to the temperature sensor 61 and receives a temperature detection result (detection signal) from the temperature sensor 61. This allows the laser controller 44 to determine the timing for changing the pitch of the welded portion 59 based on the temperature detection result.

[0094] 6, for example, the temperature of welds 59 formed in region R1 is measured sequentially, and laser controller 44 can change the small pitch P1 of welds 59 to medium pitch P2 (i.e., start forming welds in region R2) when the measured temperature reaches or exceeds a predetermined temperature (threshold value) (or when this state continues for a predetermined time). Correspondingly, the number of iron core sheets 11 constituting regions R1 and R2 is also changed.

[0095] Furthermore, as shown in FIG. 8, in the laminated core manufacturing apparatus 1 according to the second modified example, the welding device 5 can be provided independently of the progressive die 3. In the laminated core manufacturing apparatus 1 shown in FIG.

[0096] The welding device 5 has a support table 71 that supports the stacked core thin plates 11. The support table 71 is provided with a pair of fixing members 72, 72 that hold both end faces of the stacked core thin plates 11 between them.

[0097] In the welding device 5, with the stacked iron core thin plates 11 fixed to the support base 71, the laser irradiation unit 41 can move in the stacking direction along the guide rails 75. This allows the welding device 5 to weld a plurality of iron core thin plates 11 while changing the pitch of the welds 59, similar to the welding device 5 shown in FIG.

[0098] While the present invention has been described above based on specific embodiments, these embodiments are merely examples, and the present invention is not limited to these embodiments. The components of the laminated core and the manufacturing apparatus and method thereof according to the present invention shown in the above embodiments are not necessarily all essential, and can be selected appropriately as long as they do not deviate from the scope of the present invention.

[0099] For example, the welding method of the welding device 5 according to the present invention is not limited to laser welding, but may also be arc welding such as Tig (Tungsten Inert Gas) welding, Mig (Metal Inert Gas) welding, and Mag (Metal Active Gas) welding, or electron beam welding. [Explanation of symbols]

[0100] 1: Laminated core manufacturing equipment 3: Progressive die 4: Welding pattern 5: Welding equipment 11: Thin iron core plate 13: Laminated core 15: Upper mold 16: Lower mold 19: Punch 21: Punch holder 25: Stripper plate 27: Motor 29: Crankshaft 31: Encoder 33: Die 36: Squeeze ring 41: Laser irradiation unit 42: Irradiation adjustment section 43: Laser oscillator 44: Laser controller 46: Opening 47: Optical cable 51: Shaft hole 53: Central part 54: Teeth 55: Magnetic pole part 59: Welded parts 61: Temperature sensor 71: Support stand 72: Fixing member 75: Guide rail R1: First region (first group of iron core thin plates) R2: Second region (second group of iron core thin plates) R3: Third region (third core thin plate group) W: Hoop material

Claims

1. A method for manufacturing a laminated core, in which a plurality of laminated thin core plates are joined together by successively forming a plurality of spot-like welds on the plurality of laminated thin core plates, comprising: a first welding step of forming first welds constituting the plurality of welds at a first pitch in a stacking direction on a first group of iron core thin plates consisting of a portion of the plurality of iron core thin plates; a second welding step of forming second welds constituting the plurality of welds at a second pitch in the stacking direction on a second iron core thin plate group consisting of a portion of the plurality of iron core thin plates adjacent to the first iron core thin plate group after the first welding step; Including, The method for manufacturing a laminated core, wherein the second pitch is larger than the first pitch.

2. 2. The method for manufacturing a laminated core according to claim 1, further comprising a third welding step, after the second welding step, of forming third welds constituting the plurality of welds in a third group of core thin plates consisting of a portion of the plurality of core thin plates adjacent to the second group of core thin plates, at a third pitch in the stacking direction that is different from the second pitch.

3. The method for manufacturing a laminated core according to claim 2 , wherein the third pitch is larger than the second pitch.

4. The method for manufacturing a laminated core according to claim 2 , wherein the third pitch is smaller than the second pitch.

5. The method for manufacturing a laminated core according to claim 4 , wherein the third pitch is the same as the first pitch.

6. The method for manufacturing a laminated core according to claim 2 , wherein the first welding step, the second welding step, and the third welding step are repeatedly performed.

7. the first welding step further includes a temperature measuring step of sequentially measuring a temperature of the first welded portion; The method for manufacturing a laminated core according to claim 1 , wherein a timing for starting the second welding step is determined based on the temperature of the first welded portion.

8. The laminated core is composed of N (N is an integer) thin core plates, The method for manufacturing a laminated core according to claim 1 , wherein the pitch at which the welds are formed is changed so that at least one weld is formed in the Nth core thin plate.

9. A laminated core manufacturing device that joins a plurality of laminated thin core plates by continuously forming a plurality of spot-like welds on the plurality of laminated thin core plates, a laser irradiation unit that irradiates the plurality of iron core thin plates with spot-shaped laser light to form the plurality of welds; a laser controller that controls the irradiation of the laser light by the laser irradiation unit; Equipped with The laser irradiation unit is controlled by the laser controller. forming first welds constituting the plurality of welds in a first group of iron core thin plates consisting of a portion of the plurality of iron core thin plates at a first pitch in a stacking direction; forming second welds constituting the plurality of welds at a second pitch in the stacking direction for a second group of iron core thin plates that is made up of a portion of the plurality of iron core thin plates adjacent to the first group of iron core thin plates; The second pitch is larger than the first pitch.

10. a progressive die for sequentially punching out the plurality of iron core thin plates from an intermittently transferred strip-shaped thin steel plate and stacking the plurality of iron core thin plates; The laminated core manufacturing device of claim 9, wherein the laser irradiation unit is configured to irradiate the laser light into a core holding member that holds the core thin plate whose outer shape has been punched out from the strip-shaped thin steel plate in the progressive die.

11. The laser irradiation unit is controlled by the laser controller.

11. A laminated core manufacturing apparatus as described in claim 9 or 10, wherein third welds constituting the plurality of welds are formed in a third group of core thin plates consisting of a portion of the plurality of core thin plates adjacent to the second group of core thin plates at a third pitch in the stacking direction that is different from the second pitch.

12. The laminated core manufacturing device according to claim 11 , wherein the laser irradiation unit repeatedly forms the first welded portion, the second welded portion, and the third welded portion.

13. a temperature sensor that sequentially measures the temperature of the first weld; 11. The laminated core manufacturing apparatus according to claim 9, wherein the laser controller determines a timing for starting formation of the second welded portion based on the temperature of the first welded portion.

14. The laminated core is composed of N (N is an integer) thin core plates, The method for manufacturing a laminated core according to claim 9 or 10, wherein at least one welded portion is formed in the Nth core thin plate.

15. A laminated core in which a plurality of laminated thin core plates are joined together by a plurality of spot-shaped welds formed continuously on the plurality of laminated thin core plates, The plurality of welds are first welds formed at a first pitch in a stacking direction of the plurality of iron core thin plates on a first iron core thin plate group consisting of a portion of the plurality of iron core thin plates; second welds formed at a second pitch in the stacking direction on a second iron core thin plate group consisting of a portion of the plurality of iron core thin plates adjacent to the first iron core thin plate group, The second pitch is greater than the first pitch.

Images