Method for manufacturing laminated iron core, and dummy block

Abstract

The purpose of the present invention is to provide a method for manufacturing a laminated iron core with which it is possible to more reliably perform mutual fastening of iron core pieces. When laminating a plurality of iron core pieces 25 in a die 3 by sequentially punching and holding an iron core piece 25 from a steel plate 16 using a punch 1 and a die 3, the dummy block 9 is held in advance in the die 3 by friction, and while receiving the plurality of iron core pieces 25 on the dummy block 9, the adjacent iron core pieces 25 are connected by caulking, and frictional force for holding the dummy block 9 is set by an adjustment mechanism 13 provided in the dummy block 9.

Description

Manufacturing method of laminated iron core and dummy block

[0001] The present invention relates to a method for manufacturing a laminated core for a rotating electrical machine and a dummy block used therein.

[0002] A conventional method for manufacturing a laminated core uses a dummy block, as described in Patent Document 1.

[0003] In this method of manufacturing a laminated core, a dummy block is placed in a die in advance and held in a squeeze ring by friction. In this state, multiple core pieces are punched out one after another and held in the die, so that the multiple core pieces can be received on the dummy block and adjacent core pieces can be integrated by fastening them together by crimping or the like.

[0004] Therefore, even when no core pieces are held in the die, such as after maintenance of the punch or die, adjacent core pieces of the plurality of core pieces can be reliably fastened together.

[0005] However, in this manufacturing method, if the frictional force of the dummy block against the squeeze ring is not set properly, it is likely to result in incomplete fastening. Also, since the dummy block is reused, it becomes difficult to maintain the appropriate frictional force due to wear, which also leads to the problem of incomplete fastening.

[0006] Japanese Patent Application Laid-Open No. 2004-328974

[0007] The problem to be solved is that when a dummy block is used, it is easy for a connection to be made due to incomplete fastening.

[0008] The present invention provides a method for manufacturing a laminated core, in which a dummy block is held by frictional force within a die that cooperates with a punch to punch out core pieces from a steel plate, the punch and die sequentially punch out a plurality of core pieces from the steel plate, the punched core pieces are sequentially held and stacked within the die, the punched core pieces are received on the dummy block when stacking the punched core pieces within the die and adjacent core pieces of the punched core pieces are fastened together, and the frictional force for holding the dummy block within the die is set by an adjustment mechanism provided in the dummy block.

[0009] The present invention provides a dummy block used when sequentially punching out a plurality of iron core pieces from a steel plate using a punch and a die and sequentially holding and stacking the punched iron core pieces within the die, the dummy block comprising: a block body that is held within the die by frictional force and receives the punched iron core pieces to fasten adjacent iron core pieces of the punched iron core pieces; and an adjustment mechanism that sets the frictional force for holding the block body within the die.

[0010] In the present invention, the use of a dummy block allows for more appropriate fastening.

[0011] FIG. 1 is a cross-sectional view showing a laminated core manufacturing apparatus using a dummy block according to a first embodiment of the present invention. FIG. 2 is a plan view of the laminated core manufacturing apparatus of FIG. 1. FIG. 3 is a cross-sectional view of the dummy block of FIG. 2 taken along line III-III. FIG. 4 is an enlarged plan view of a portion of the dummy block of FIG. 3. FIG. 5 is a cross-sectional view showing a portion of the laminated core of the first embodiment. FIG. 6 is a plan view of a dummy block according to a second embodiment of the present invention. FIG. 7 is a cross-sectional view of the laminated core manufacturing apparatus corresponding to line VII-VII in FIG. 6. FIG. 8 is a plan view of a dummy block according to a modified example of the second embodiment. FIG. 9 is a cross-sectional view of the laminated core manufacturing apparatus corresponding to line IX-IX in FIG. 8. FIG. 10 is a plan view of a dummy block according to a third embodiment of the present invention. FIG. 11 is a cross-sectional view of FIG. 10 taken along line XI-XI. FIG. 12 is a cross-sectional view of FIG. 10 taken along line XII-XII. FIG. 13 is a cross-sectional view of a dummy block according to a fourth embodiment of the present invention. FIG. 14 is a plan view of the dummy block of FIG. 13. Fig. 15 is a cross-sectional view showing the relationship between a dummy block and a squeeze ring according to a fifth embodiment of the present invention. Fig. 16 is a plan view showing the dummy block and squeeze ring of Fig. 15. Fig. 17 is a cross-sectional view showing the relationship between a dummy block and a squeeze ring according to a modification of the fifth embodiment.

[0012] In one embodiment of the manufacturing method for a laminated core, a dummy block 9 is held by friction within a die 3 that cooperates with a punch 1 to punch out core pieces 25 from a steel plate 16. A plurality of core pieces 25 are then punched out sequentially from the steel plate 16 by the punch 1 and die 3, and the punched core pieces 25 are sequentially held and stacked within the die 3. When stacking the punched core pieces 25 within the die 3, the punched core pieces 25 are received on the dummy block 9, and adjacent core pieces 25 of the punched core pieces 25 are fastened together. The friction force for holding the dummy block 9 in the die 3 is set by an adjustment mechanism 13 provided in the dummy block 9.

[0013] In one embodiment, the friction force may be set by pressing an engagement screw 15 provided in the adjustment mechanism 13 against the die 3 .

[0014] In another embodiment, the friction force may be set by pressing the pressing members 51 and 63 provided in the adjustment mechanism 13 against the die 3, and the pressing members 51 and 63 may be moved by the drive screws 41 and 53 or biased by the biasing member 63.

[0015] In another embodiment, the friction force may be set by pressing the movable parts 37 and 39 of the dummy block 9 against the die 3 , and the movable parts 37 and 39 may be moved by a drive screw 41 of the adjustment mechanism 13 .

[0016] A plurality of dummy blocks 9 may be stacked in accordance with the thickness of the laminated core, and the dummy blocks 9 at least at both ends in the stacking direction may be fastened together.

[0017] In another embodiment, a plurality of dummy blocks 9 may be stacked in accordance with the thickness of the laminated core, and adjacent dummy blocks 9 among the stacked dummy blocks 9 may be joined together.

[0018] The dummy block 9 may be held by friction between the outer periphery and the die 3 or by friction between the inner periphery and a press-fit bar disposed within the die 3 .

[0019] [Laminated Core Manufacturing Apparatus] Fig. 1 is a cross-sectional view showing a laminated core manufacturing apparatus using a dummy block according to Example 1 of the present invention. Fig. 2 is a plan view of the laminated core manufacturing apparatus of Fig. 1.

[0020] 1 and 2 is a manufacturing apparatus for a laminated core, for example, a motor core for a rotating electrical machine, and includes a punch 1 and a die 3 that cooperates with the punch 1 to punch out core pieces 25 from a steel plate 16. The die 3 in this embodiment includes a die body 4 supported by a die holder 5 and a squeeze ring 7.

[0021] The die body 4 is ring-shaped and has a flat circular inner periphery. The die body 4, together with the ascending and descending punch 1, successively punches out disc-shaped core pieces 25 from a strip-shaped steel sheet 16 such as an electromagnetic steel sheet or a silicon steel sheet.

[0022] The squeeze ring 7 is formed in a ring shape that is longer in the punching direction than the die body 4, and has a flat circular inner periphery. The punching direction coincides with the stacking direction of the core pieces 25 and the dummy blocks 9. The squeeze ring 7 is disposed adjacent to the die body 4 in the punching direction of the core pieces 25. The inner diameter of the squeeze ring 7 is slightly smaller than the inner diameter of the die body 4.

[0023] The squeeze ring 7 is a part that applies lateral pressure to the punched core pieces 25 to hold them in place by pressing them from the outer periphery. It is also possible to omit the squeeze ring 7. In this case, the die body 4 can be extended in the punching direction or the die holder 5 can be reduced in diameter to provide the squeeze ring 7 function.

[0024] The dummy block 9 is held by frictional force within the die 3. The dummy block 9 is held within the die 3 in a state where there are no previously punched core pieces 25 present within the die 3, and receives and stacks the punched core pieces 25 one after another.

[0025] In this embodiment, four layers of dummy blocks 9 are held in advance in the die 3. The total thickness of the four layers of dummy blocks 9 is the same as the thickness of the motor core as a laminated core. The thickness of each dummy block 9 is the same as that of a block formed by laminating a predetermined number of core pieces 25. Multiple blocks, four in this embodiment, are laminated and integrated to form the motor core.

[0026] The number of dummy blocks 9 can be any number as long as the core pieces 25 can be joined by crimping. For example, two layers of dummy blocks 9 can be provided, or the thickness of one or more layers of dummy blocks 9 can be 90% of the thickness of the motor core.

[0027] Fig. 3 is a cross-sectional view of the dummy block taken along line III-III of Fig. 2. Fig. 4 is an enlarged plan view of a portion of the dummy block of Fig. 3.

[0028] As shown in Figures 1 to 3, each dummy block 9 includes a block body 10 and an adjustment mechanism 13. The block body 10 is formed in a disk or cylindrical shape and made of resin or the like. This block body 10 is held within the die 3 by frictional force, receives the punched core pieces 25, and fastens adjacent ones of the punched core pieces 25 together. The planar shape of the block body 10 can be set as desired, but a circular shape is preferable in order to receive the disk-shaped core pieces 25. The material of the block body 10 can also be selected as desired, but a lightweight material such as resin is suitable.

[0029] The diameter of the outer peripheral surface of the block body 10 is set to be slightly smaller than the inner diameter of the die body 4. The block body 10 is provided with an adjustment mechanism 13.

[0030] The adjustment mechanism 13 sets a frictional force for holding the block body 10 in the die 3. The adjustment mechanism 13 of this embodiment includes an engagement screw 15. The engagement screw 15 is, for example, a bolt made of resin. By making the engagement screw 15 out of resin, damage to the die body 4 and the squeeze ring 7 can be suppressed. The engagement screw 15 is arranged from a hole 17 formed in the block body 10 of the dummy block 9 to the outer periphery of the block body 10.

[0031] The holes 17 are arranged, for example, at four locations circumferentially of the block body 10, at 90° intervals. The number and arrangement of the screw arrangement holes 17 can be set arbitrarily. The number and arrangement of the engaging screws 15 in the circumferential direction can also be set arbitrarily depending on the number and arrangement of the screw arrangement holes 17. The number and arrangement of the engaging screws 15 in the stacking direction can also be set arbitrarily. For example, the dummy blocks 9 in the second and subsequent layers may be configured without engaging screws 15. The dummy blocks 9 (block body 10) without engaging screws 15 can also be formed in a simple disk shape.

[0032] A screw head 15a of an engagement screw 15 is positioned in each hole 17, and a threaded portion 15b of the engagement screw 15 is threaded into a screw hole 10a provided along the radial direction of the block body 10. The screw hole 10a may be provided along a direction intersecting the radial direction.

[0033] The tip of the threaded portion 15b of the engagement screw 15 protrudes from the outer peripheral surface of the dummy block 9 and frictionally engages with the inner peripheral surface of the squeeze ring 7. The tip surface of the threaded portion 15b of the engagement screw 15 is flat, but can also be curved in accordance with the inner peripheral surface of the squeeze ring 7.

[0034] The friction force of the dummy block 9 against the squeeze ring 7 of the die 3 is set by pressing the engagement screw 15 against the die body 4. The engagement screw 15 is pressed by manipulating the screw head 15a of the engagement screw 15 with a tool inserted into the hole 17.

[0035] In this embodiment, as shown in Figure 4, a collar 19 for setting the pressing force is added. The collar 19 is interposed between the screw head 15a of the engagement screw 15 and the inner surface of the hole 17. When the screw head 15a is tightened into the inner surface of the hole 17, the length of the threaded portion 15b that protrudes from the outer peripheral surface of the dummy block 10 is set by the collar 19.

[0036] [Method of Manufacturing Laminated Core] FIG. 5 is a cross-sectional view showing a part of the laminated core of the first embodiment.

[0037] In the manufacturing method of the laminated core of this embodiment, a strip-shaped steel sheet 16 is fed to a die device, and after undergoing a predetermined pressing process to form the motor core shape, the outer shape is punched out as shown in Figure 1. In punching out the outer shape, a plurality of core pieces 25 are punched out one after another from the steel sheet 16 using a punch 1 and a die 3, and the punched core pieces 25 are successively held and stacked within the die 3. In this way, a motor core, which is a laminated core of a predetermined thickness, is manufactured.

[0038] In this embodiment, blocks having a stacking height lower than the motor core are formed, and multiple blocks are stacked with their phases changed. However, the iron core pieces 25 may be stacked with their phases changed, or the iron core pieces 25 may be stacked without changing their phases.

[0039] 1, in punching out the outer shape, the dummy blocks 9 are used in a state where there are no previously punched core pieces 25 present in the die 3, such as after maintenance of the punch 1 or the die 3. In this embodiment, four layers of dummy blocks 9 are used.

[0040] Each dummy block 9 is inserted into the die body 4 with the engaging screws 15 loosened. Then, by tightening the engaging screws 15, the tip of the threaded portion 15b of each engaging screw 15 protrudes a set length from the outer periphery of the dummy block 9. The protruding length of the threaded portion 15b is set to a length that allows the dummy block 9 to frictionally engage with the inner diameter of the squeeze ring 7, which is slightly smaller than the inner diameter of the die body 4, with a set frictional force. This setting is performed by rotating the screw head 15a with a tool through the hole 17 in the block body 10.

[0041] In this way, the dummy block 9 is pressed into the smaller-diameter squeeze ring 7 while the protruding amounts of the tips of the engaging screws 15 are adjusted within the die body 4. The pressing is performed by driving the dummy block 9, with the engaging screws 15 fastened, into the die body 4 with a hammer or the like.

[0042] At this time, the surface of the dummy block 9 need only be roughly horizontal in the direction perpendicular to the stacking direction. Even if it is driven in at a slight angle, the surface of the dummy block 9 will conform to the punch 1 when the first core piece 25 is punched onto the dummy block 9. In this way, the dummy block 9 is held within the die 3 by frictional force.

[0043] When punching out the core pieces 25, the processed strip-shaped steel sheet 16 is transferred onto the die 3, and the outer periphery is punched out by the punch 1 while an upper die stripper (not shown) holds down the steel sheet 16.

[0044] The core piece 25 that is first punched into the die 3 is received by being pressed onto the dummy block 9 at the upper end by the punch 1. At this time, the dummy block 9 can reliably receive the core piece 25 with a frictional reaction force. The frictional reaction force of the dummy block 9 is mainly generated by the dummy block 9 located inside the squeeze ring 7.

[0045] When the second layer of core pieces 27 is punched out, it is stacked on the first core piece 25 and received on the dummy block 9. As a result, the dummy block 9 moves down within the die 3 due to the thickness of the core pieces 25.

[0046] At this time, as shown in Figure 5, the convex portion of the crimping portion 23 of the second-layer core piece 27 fits into the crimping hole 21 of the bottom-layer core piece 25. This fitting is ensured by the core piece 25 being received on the dummy block 9 and pressed by the punch 1. In this way, the adjacent core pieces 25, that is, the first-layer and second-layer core pieces 25, are fastened together by the crimping portion 23 and the crimping hole 21.

[0047] 5 are formed in a press process before punching out the outer periphery. The crimping holes 21 and crimping portions 23 are an example of fastening, and other shapes may also be used. The core piece 25 in the lowest layer has the crimping holes 21 formed therein, and the core pieces 27 stacked one on top of the core piece 25 in the lowest layer have the crimping portions 23 with a convex portion on one side and a concave portion on the other side.

[0048] When the third-layer core pieces 27 are punched out in the same manner, they are stacked on the second-layer core pieces 25 and received on the dummy block 9. As a result, the dummy block 9 moves further down within the die 3 in accordance with the thickness of the core pieces 25, and the convex portions of the crimped portions 23 of the third-layer core pieces 25 fit into the concave portions of the crimped portions 23 of the second-layer core pieces 25. In this way, the adjacent second-layer and third-layer core pieces 25 are fastened together by the crimped portions 23.

[0049] Similarly, a preset number of core pieces 25 are stacked and adjacent core pieces 25 are fastened together. The lowering of the dummy block 9 can be started at an appropriate timing, for example, when the first core piece 25 is punched out, or when the next several core pieces 25 are punched out.

[0050] In this manufacturing method, the dummy blocks 9 fall one after another due to their own weight after passing through the squeeze ring 7. The fallen dummy blocks 9 are then pushed out in the radial direction by a pusher (not shown) or the like and carried out. The dummy blocks 9 are then prepared for repeated use.

[0051] The removal of the dummy block 9 can be automated based on a laminated core manufacturing program, and smooth operation up to removal can be achieved by making the thickness of the dummy block 9 the same as that of the block.

[0052] As described above, in the manufacturing method of the laminated core, the dummy block 9 is used, and this dummy block 9 is provided with the adjustment mechanism 13. The friction force for holding the dummy block 9 in the die 3 is set by the adjustment mechanism 13.

[0053] Therefore, the frictional force of the dummy block 9 can be easily and reliably set by the adjustment mechanism 13, and the iron core pieces 25 can be more appropriately joined by caulking.

[0054] In this embodiment, the frictional force is set by pressing the engaging screw 15 against the die 3, so that it can be set easily and reliably, and it is also easy to reset repeatedly. Furthermore, the dummy block 9 is adjusted to the amount of protrusion of the tip of the threaded portion 15b of the engaging screw 15 by the die body 4, and in that state is pressed into the smaller-diameter squeeze ring 7, so that it is easy to hold the dummy block 9 against the die 3 by friction.

[0055] The dummy blocks 9 have a thickness corresponding to the blocks that make up the laminated core, and multiple blocks are stacked according to the thickness of the laminated core, so they can be discharged using the same process as the laminated core according to the laminated core production program.

[0056] Since the engaging screw 15 is made of resin, it allows smooth movement between the die body 4 and the squeeze ring 7 and also prevents the die body 4 and the squeeze ring 7 from being damaged.

[0057] Fig. 6 is a plan view showing a dummy block according to Example 2. Fig. 7 is a cross-sectional view of a laminated core manufacturing apparatus corresponding to line VII-VII in Fig. 6. Note that Example 2 has a basic configuration in common with Example 1, and components that are the same as or correspond to those in Example 1 are designated by the same reference numerals, and redundant explanations will be omitted.

[0058] 6 and 7 , in the manufacturing method of the laminated core of Example 2, the dummy blocks 9 have a thickness corresponding to the blocks that make up part of the motor core in the lamination direction, as in Example 1, and multiple, for example, four, dummy blocks 9 are stacked according to the thickness of the motor core. Adjacent dummy blocks 9 of the four stacked layers are joined together with fixing screws 29 that serve as fasteners.

[0059] Each of the four layers of dummy blocks 9 has relief holes 33 with counterbore 31 and screw holes 35 formed therethrough in the stacking direction. These relief holes 33 and screw holes 35 are formed on intersecting diameters (diameters that intersect at right angles in this embodiment) in each dummy block 9 and are arranged on the same imaginary circle.

[0060] The four layers of dummy blocks 9 are offset in phase in the circumferential direction so that the relief holes 33 of the upper layer are concentric with the screw holes 35 of the lower layer. These four layers of dummy blocks 9 are inserted into the die 3 in order, starting with the dummy block 9 of the first layer, which is the lowest layer.

[0061] That is, the dummy block 9 for the first layer is inserted into the die body 4, and after adjusting the engaging screw 15, it is press-fitted into the squeeze ring 7. Next, the dummy block 9 for the second layer is placed on top of the dummy block 9 for the first layer with the phases shifted, and both dummy blocks 9 are fastened together with the fixing screw 9.

[0062] After this fastening, the second layer of dummy blocks 9 is press-fitted into the squeeze ring 7. Similarly, the third and fourth layers of dummy blocks 9 are stacked and fastened in order, and the four layers of dummy blocks 9 are placed in an integrated state inside the die 3 as shown in FIG.

[0063] Therefore, in this embodiment, even when multiple dummy blocks 9 are stacked together to have the same thickness as the motor core, the frictional force of the dummy blocks 9 of each layer can be appropriately adjusted while they are reliably placed within the die 3.

[0064] Furthermore, the work of using the engaging screws 15 and the fixing screws 29 of each dummy block 9 can be performed near the surface of the die 3, improving workability. Note that the fixing of the dummy blocks 9 with the fixing screws 29 may be performed on only some of the dummy blocks 9 among the multiple layers of dummy blocks 9.

[0065] The dummy blocks 9 can also be pressed into the die 3 from the surface of the die 3 in order, so that the dummy blocks 9 can be pressed in easily and reliably.

[0066] In addition, the second embodiment can also achieve the same effects as the first embodiment.

[0067] [Modification] Fig. 8 is a plan view showing a dummy block according to a modification of Example 2. Fig. 9 is a cross-sectional view of a laminated core manufacturing apparatus taken along line IX-IX in Fig. 8 .

[0068] In the modified example shown in FIGS. 8 and 9, the dummy blocks 9 at both ends in the stacking direction of the four stacked dummy blocks 9 are fastened to each other.

[0069] That is, in the four dummy blocks 9, the relief holes 33 and screw holes 35 are out of phase with each other between the dummy block 9 in the first layer and the dummy blocks 9 in the second to fourth layers. The relief holes 33 and screw holes 35 are in phase with each other between the dummy blocks 9 in the second to fourth layers.

[0070] The fixing screws 29 thread from the countersunk holes 31 on the surface of the fourth-layer dummy block 9 through relief holes 33 in the second to fourth layers into the threaded holes 35 in the first-layer dummy block 9. This allows the dummy blocks 9 between the first and fourth layers at both ends in the stacking direction to be fastened together. The fixing screws 29 are simply inserted into the dummy blocks 9 in the second and third layers, and are not threaded into them.

[0071] However, the four layers of dummy blocks 9 only need to be fastened and fixed at least between both ends in the stacking direction, and it is also possible for only the second layer dummy blocks 9 or only the third layer dummy blocks 9 to have no fixing screws 29 threaded therein.

[0072] In the four-layer dummy blocks 9 shown in FIG. 8, the adjustment mechanisms 13 are provided on the first to fourth layers of the dummy blocks 9 .

[0073] Therefore, the adjustment work for the fixing screws 29 and the adjustment mechanisms 13 can be reduced compared to Example 2. In addition, this modified example can also achieve the same effects as Example 2. The adjustment mechanisms 13 for the dummy blocks 9 in the second and third layers can be omitted. Also, the adjustment mechanisms 13 for the dummy blocks 9 in the second and third layers can be left in a loose state without functioning. In other words, the dummy blocks 9 in the second and third layers can be configured so that frictional force adjustment is not performed.

[0074] Fig. 10 is a plan view showing a dummy block according to Example 3. Fig. 11 is a cross-sectional view taken along line XI-XI of Fig. 10. Fig. 12 is a cross-sectional view taken along line XII-XII of Fig. 10. Note that, since Example 3 has a basic configuration in common with Example 1, the same reference numerals are used to indicate the same or corresponding configurations as Example 1, and redundant explanations will be omitted.

[0075] 10 , in Example 3, the block body 10 of the dummy block 9 has movable parts 37 and 39 that frictionally engage with the die 3. The adjustment mechanism 13 has a drive screw 41 that moves the movable parts 37 and 39. The friction force of the dummy block 9 against the die 3 is set by pressing the movable parts 37 and 39 against the die 3.

[0076] The movable parts 37 and 39 in this embodiment have a shape obtained by dividing the block body 10 of the disk-shaped or cylindrical dummy block 9 into two halves. The outer peripheral surfaces 37a and 39a of the movable parts 37 and 39 are located on approximately the same circumference. However, the movable parts 37 and 39 may have any shape as long as they can abut against the die body 4 of the die 3 and the inner periphery of the squeeze ring 7.

[0077] The drive screw 41 has reverse threads at both ends, and is threadedly engaged with the movable parts 37 and 39. The drive screw 41 has an operating part 41a, such as a hexagonal part, that is located in the space 49 between the movable parts 37 and 39. The operating part 41 can be manually operated using a tool. The drive screw 41 rotates when the operating part 41 is operated, and drives the movable parts 37 and 39 to move closer to or farther away from each other.

[0078] 11, a concave-convex guide 43 is provided between the movable parts 37 and 39. The guide 43 is arranged in two locations on the movable parts 37 and 39. The guide 43 is composed of a concave part 45 on the movable part 37 and a convex part 47 on the movable part 39. The concave part 45 and the convex part 47 fit together in the stacking direction and are slidable in the driving direction of the movable parts 37 and 39.

[0079] In the dummy block 9, the hexagonal portion 41 a is rotated with a tool to move the movable portions 37 and 39 relatively to each other. This allows the dimensions of the movable portions 37 and 39 of the dummy block 9 in the driving direction to be set, and the frictional force of the dummy block 9 against the squeeze ring 7 of the die 3 to be set.

[0080] Therefore, in the third embodiment, by setting the frictional force that causes frictional engagement by pressing the movable parts 37 and 39 against the die 3, it is possible to achieve the same effects as in the first embodiment.

[0081] Fig. 13 is a cross-sectional view showing a dummy block according to Example 4. Fig. 14 is a plan view of the dummy block of Fig. 13. Note that, since Example 4 has a basic configuration in common with Example 1, the same reference numerals are used to indicate the same or corresponding configurations as Example 1, and redundant explanations will be omitted.

[0082] 13 and 14 , in Example 4, the adjustment mechanism 13 includes a pressing member 51 that frictionally engages with the die 3 and a drive screw 53 that moves the pressing member 51. The friction force of the dummy block 9 against the die 3 is set by the pressing of the pressing member 51 against the die 3.

[0083] For example, four pressing members 51 are provided. Each pressing member 51 is a rod-shaped member made of resin. The pressing members 51 are slidably disposed in radial slide holes 55 formed in the dummy block 9. A driving slope 51a is formed on the radial inner end of each pressing member 51.

[0084] The slide holes 55 are arranged at four locations in the circumferential direction of the dummy block 9. The tip of the pressing member 51 protrudes from each of the slide holes 55 from the outer peripheral surface of the dummy block 9. This protrusion of the pressing member 51 causes the pressing member 51 to frictionally engage with the inner peripheral surface of the squeeze ring 7. The tip surface of the pressing member 51 is formed into a curved shape or a flat surface according to the inner peripheral surface of the squeeze ring 7.

[0085] The frictional force of the dummy block 9 against the squeeze ring 7 of the die 3 is set by the pressing of a pressing member 51. The pressing of the pressing member 51 is performed by driving a wedge member 57 that abuts against the inclined surface 51 a of the pressing member 51 with a drive screw 53. The drive screw 53 is threaded into a screw hole 61 of the dummy block 9.

[0086] An opening 59 is formed in the center of the dummy block 9. The drive screw 53 is accessible through the opening 59.

[0087] Therefore, in this embodiment, when the drive screw 53 is rotated through the opening 59, the wedge member 57 presses the inclined surface 51 a of the pressing member 51, causing the pressing member 51 to move relatively away from the dummy block 9. This moving away adjusts the amount by which the tip of the pressing member 51 protrudes from the outer circumferential surface of the dummy block 9. Depending on the amount of protrusion of the pressing member 51, the frictional force of the dummy block 9 against the inner periphery of the squeeze ring 7 of the die 3 can be set.

[0088] In the fourth embodiment, the frictional force generated by the multiple pressing members 51 can be set by operating the single drive screw 53, making the operation simple. The drive screw 53 can be accessed through the opening 59 with a general tool such as a wrench or a screwdriver, making the operation extremely easy. In addition, the frictional force can be easily set uniformly in the circumferential direction.

[0089] In addition, the fourth embodiment can also achieve the same effects as the first embodiment.

[0090] Fig. 15 is a cross-sectional view showing the relationship between a dummy block and a squeeze ring according to Example 5. Fig. 16 is a plan view showing the dummy block and squeeze ring of Fig. 15. Note that Example 5 has a basic configuration in common with Example 1, and therefore, the same or corresponding components as those in Example 1 are denoted by the same reference numerals, and redundant explanations will be omitted.

[0091] As shown in FIGS. 15 and 16, in the fifth embodiment, the adjustment mechanism 13 of the dummy block 9 includes a pressing member 63 and a biasing member 65 instead of the engaging screw 15 of the first embodiment.

[0092] The adjustment mechanism 13 includes a pressing member 63 that performs frictional engagement and a biasing member 65 that biases the pressing member 63 to protrude. The biasing member 65 is an elastic body such as rubber or a spring.

[0093] The pressing member 63 is a rod-shaped body made of resin and is composed of a shaft portion 63a and a head portion 63b. A concave spring bearing 63c is formed in the head portion 63b. A concave spring bearing 17a is formed on the radially inner side of the hole 17. The spring bearing 17a and the spring bearing 63c face each other in the radial direction, and a biasing member 65 is interposed between them.

[0094] Therefore, in this embodiment, the biasing member 65 in the hole 17 biases the pressing member 63 radially outward of the dummy block 9. This sets the frictional force for holding the dummy block 9 against the die 3.

[0095] In addition, the fifth embodiment can also achieve the same effects as the first embodiment.

[0096] [Modification] FIG. 17 is a cross-sectional view of a main part showing the relationship between a dummy block and a squeeze according to a modification.

[0097] In the modification shown in FIG. 17, the pressing member 63 and the biasing member 65 are unitized in a frame 67, which is fitted into the outer peripheral surface of the dummy block 9 and attached thereto.

[0098] Therefore, the pressing member 63 and the biasing member 65 can be easily replaced by attaching and detaching the frame body 67. In addition, the same effects as those of Example 5 can be achieved. In the dummy blocks 9 of Examples 1 to 5 described above, the dummy blocks 9 of Examples 1 and 3 to 5 can also be used in appropriate combination.

[0099] REFERENCE SIGNS LIST 1 punch 3 die 4 die body 7 squeeze ring 9 dummy block 10 block body 13 adjustment mechanism 15 engagement screw 17 hole 23 crimped portion 25 core piece 27 core piece 29 fixing screw 37, 39 movable portion 41, 53 drive screw 51, 63 pressing member 65 biasing member

Claims

1. A method for manufacturing a laminated core, comprising: holding a dummy block by frictional force in a die that punches out core pieces from a steel sheet in cooperation with a punch; sequentially punching out a plurality of core pieces from the steel sheet by the punch and the die, and sequentially holding and laminating the punched core pieces in the die; receiving the punched core pieces on the dummy block when laminating the punched core pieces in the die, and fastening adjacent core pieces of the punched core pieces; and setting the frictional force for holding the dummy block in the die by an adjustment mechanism provided in the dummy block.

2. The method for manufacturing a laminated core according to claim 1, wherein the frictional force is set by pressing an engagement screw provided in the adjustment mechanism against the die.

3. The method for manufacturing a laminated core according to claim 1, wherein the frictional force is set by pressing a pressing member provided in the adjustment mechanism against the die, and the pressing member is moved by a driving screw or biased to protrude by a biasing member.

4. The method for manufacturing a laminated core according to claim 1, wherein the frictional force is set by pressing a movable part provided in the dummy block against the die, and the movable part is moved by a driving screw provided in the adjustment mechanism.

5. The method for manufacturing a laminated core according to any one of claims 1 to 4, wherein a plurality of the dummy blocks are laminated according to the thickness of the laminated core, and at least the dummy blocks at both ends in the lamination direction are fastened to each other.

6. The method for manufacturing a laminated core according to any one of claims 1 to 4, wherein a plurality of the dummy blocks are laminated according to the thickness of the laminated core, and adjacent dummy blocks in the laminated dummy blocks are joined to each other.

7. A dummy block used when sequentially punching out a plurality of core pieces from a steel sheet by a punch and a die, sequentially holding and laminating the punched core pieces in the die, comprising: a block body that is held in the die by frictional force and receives the punched core pieces to fasten adjacent core pieces of the punched core pieces; and an adjustment mechanism that sets the frictional force for holding the block body in the die.

8. A dummy block according to claim 7, wherein the adjusting mechanism includes an engaging screw, and the frictional force is set by pressing the engaging screw against the die. Dummy block.

9. A dummy block according to claim 7, wherein the adjusting mechanism includes a pressing member and a drive screw for moving the pressing member or a biasing member for biasing the pressing member to protrude, and the frictional force is set by pressing the pressing member against the die. Dummy block.

10. A dummy block according to claim 7, wherein the block body includes a movable part, the adjusting mechanism includes a drive screw for moving the movable part, and the frictional force is set by pressing the movable part against the die. Dummy block.

11. A dummy block according to claim 8, wherein the engaging screw is made of resin. Dummy block.

12. A dummy block according to claim 9, wherein the pressing member is made of resin. Dummy block.

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