EP2919242B1

EP2919242B1 - Coil and fabrication device therefor, and coil fabrication method

Info

Publication number: EP2919242B1
Application number: EP13853614.9A
Authority: EP
Inventors: Yusuke TSUJIMURA
Original assignee: Toshiba Industrial Products and Systems Corp
Current assignee: Toshiba Industrial Products and Systems Corp
Priority date: 2012-11-07
Filing date: 2013-10-18
Publication date: 2019-04-24
Anticipated expiration: 2033-10-18
Also published as: EP2919242A4; CN104798151B; ES2730687T3; EP2919242A1; RU2611723C2; JP2014096402A; CN104798151A; RU2015121638A; JP6022901B2; WO2014073352A1

Description

Embodiments described herein relate to a coil, a coil manufacturing apparatus and a coil manufacturing method.
There has conventionally been provided a static induction electrical apparatus for power generation or for industrial use, for example, a transformer including a coil configured by winding a band-shaped metal sheet serving as a conductor around a former. Cylindrical and rectangular cylindrical formers are used depending upon specifications of this type of coil. The metal sheet is wound on the former together with an insulating sheet made of an insulation material, thereby forming multiple layers . A cooling duct is provided in any one of the layers.
It is desirable to improve a dimensional accuracy of the coil by winding the metal sheet in a manner such that the metal sheet adheres closely to the former or in another manner. However, springback inevitably results in gaps between the layers depending upon the rigidity of the metal sheet even when a winding torque of the former is increased. The gaps result in not only a bulging part (reduction in dimensional accuracy) of the wound coil but also widthwise displacement of the metal sheet during the winding. In this case, in order that the displacement may be corrected, the winding is once stopped and meandering correction then needs to be carried out at an uncoiled side (a material supply side), with the result of increase in work burden.
Japanese Patent Application Publication JP-A-2001-332435 discloses an electromagnet coil winding device in which a bending radius of a bent conductor regarding a relatively thicker conductive wire 1 is continuously measured and the measurements are fed back to a bending apparatus 3 thereby to control the bending apparatus. The conductive wire 1 is a thicker wire having a substantially circular cross section or twisted wire.
Japanese Patent Application Publication JP-A-H06-295825 discloses a winding method in which a sheet conductor 2 is wound on an iron core 1 having a rectangular outer peripheral configuration as viewed in the direction of axis of a rotating shaft. The sheet conductor 2 is formed into a thin strip shape. Nothing is disclosed regarding bending.
Embodiments will be described merely by way of example, with reference to the accompanying drawings in which:

FIG. 1 is a conceptual diagram showing an overall coil manufacturing apparatus according to a first embodiment;
FIG. 2 is a schematic block diagram showing an electrical arrangement of the coil manufacturing apparatus;
FIG. 3 is a schematic perspective view of the coil structure;
FIG. 4A is a side view of the octagonal coil as viewed in an axial direction of the former and FIGS. 4B, 4C and 4D are similar to FIG. 4A, showing the coils provided with various cooling ducts respectively; and
FIG. 5 is a view similar to FIG. 1, showing a reference example.

In general, according to one embodiment, a coil manufacturing apparatus includes an unrolling unit configured to unroll a band-shaped metal sheet wound on a winding body and a former configured to rewind the metal sheet while rotating the metal sheet. The apparatus comprises a feeder provided between the unrolling unit and the former to feed the metal sheet unrolled by the unrolling unit, to the former side, a bending unit configured to carry out a bending process in which the metal sheet fed by the feeder is bent before the metal sheet is wound onto the former, the bending unit being configured to form a widthwise extending crease on the metal sheet, the crease corresponding to a corner of the former or a corner of the metal sheet lap-wound on the former; and a control unit configured to control the bending process by the bending unit based on a feed amount of the metal sheet by the feeder so that a winding start of the metal sheet is shaped according to an outer peripheral shape of the former and thereafter, according to an outer peripheral shape of the metal sheet lap-wound onto the former. The former has an outer peripheral shape which is polygonal as viewed in an axial direction of a rotation axis thereof. The control unit is configured to control the bending process by the bending unit so that a crease according to a winding amount of the metal sheet is imparted to the metal sheet before the metal sheet is wound onto the former.
A first embodiment will be described with reference to FIGS . 1 to 4D. The embodiment is applied to a coil used in a transformer.
A coil 1 to be manufactured includes a band-shaped metal sheet 2, a band-shaped insulating sheet 3 both of which are wound on a former (see reference symbol 16 in FIG. 1) into multiple layers further formed into a rectangular cylindrical shape as a whole. The metal sheet 2 is a thin sheet material made of a metal such as aluminum, and the insulating sheet 3 is a piece of broken or interposed sheet, for example. The coil 1 is formed to have no displacement in a widthwise direction of the metal sheet 2 as designated by symbol W in FIG. 3 and to have no gaps between the layers constituting a multilayer coil. The metal sheet 2 may be formed of another metal material such as copper.
In FIG. 1 showing the manufacturing apparatus for the coil 1, reference symbol 11 designates a roll body made by winding the metal sheet 2 into a hoop shape, and reference symbol 12 designates an uncoiler which unrolls the metal sheet 2. Reference symbol 13 designates a leveler correcting a winding tendency of the metal sheet 2, reference symbol 14 designates a feeder for intermittently feeding the metal sheet 2 and reference symbol 15 designates a bending apparatus as a bending unit for the metal sheet 2.
More specifically, the roll body 11 is the metal sheet 2 as a hoop-shaped material wound into the hoop shape and is attached to an attachment part 12a of the uncoiler 12. The roll body 11 is rotatably supported by the attachment part 12a. The uncoiler 12 is configured as an unrolling unit which is rotated in a direction opposed to the winding direction of the roll body 11 thereby to unroll the metal sheet 2.
The leveler 13 includes a plurality of work rolls 13a, 13b and 13c arranged into a zigzag as shown in FIG. 1. A winding tendency of the unrolled metal sheet 2 is corrected by causing the metal sheet 2 to pass between the upper work rolls 13a and 13c and the lower work roll 13b, and the upper and lower work rolls 14a and 14b.
The feeder 14 performs an intermittent feeding operation of feeding the metal sheet 2 from which the winding tendency has been eliminated by the leveler 13, toward the bending apparatus 15 and stopping the feeding of the metal sheet 2, repeatedly alternately. In more detail, the feeder 14 includes the paired rolls 14a and 14b holding the metal sheet 2 therebetween and an electric motor 14c (see FIG. 2) driving the paired rolls 14a and 14b, for example. The motor 14c comprises a servo motor, for example and is provided with an encoder 14d (see FIG. 2) which detects an amount of rotation of the motor 14c so that the motor 14c is feedback controlled. A feed amount of the metal sheet 2 by the feeder 14 is calculated by the control device 20 which will be described later, based on a detection signal of the encoder 14d. The rolls 14a and 14b of the feeder 14 are disposed closely to the bending apparatus 15 in front of the bending apparatus 15 in the feed direction (at a location near the input side of the bending apparatus 15) so that an error in the forming of the coil 1 due to a bending tendency is prevented between the rolls 14a and 14b and the bending apparatus 15. The rolls 14a and 14b are made of a material or have surface profiles such that respective surfaces have a large frictional resistance against the metal sheet 2, and the rolls 14a and 14b are set to a predetermined applied pressure (a holding force), with the result that a conveying accuracy can be improved.
The bending apparatus 15 is disposed between the feeder 14 and the former 16 and carries out a bending process in which the metal sheet 2 is bent before wound onto the former 16. The bending apparatus 15 includes a bending die 17a and a presser mechanism 17b which bends the metal sheet 2 so that the metal sheet 2 is plastically deformed at a predetermined angle along the bending die 17a. Various types of bending dies 17a are prepared according to an outer peripheral configuration of the former 16 or shapes of the coils to be manufactured. The presser mechanism 17b is configured to abut against the metal sheet 2 in the through-thickness direction. The metal sheet 2 is bent 90° as viewed in the widthwise direction thereof (the vertical direction to the paper of FIG. 1), for example. The bending apparatus 15 thus forms a widthwise extending crease (a folding tendency) corresponding to a corner of the former 16 or a corner of the metal sheet 2 wound on the former 16. In the case of coils 101 to 104 as shown in FIG. 4, the bending apparatus 15 forms a folding tendency to bend at 45° in the metal sheet 2 and forms a folding tendency according to shapes and/or dimensions of the ducts 18 in the coils 103 and 104 so that no gaps are formed between the layers of the metal sheet 2.
The former 16 has a rotating shaft 16a about which the former 16 is rotated to rewind the metal sheet 2 and the insulating sheet 3. Various types of formers 16 are prepared according to the shape and size of the coil 1 (the vertical and horizontal dimensions as viewed in FIG. 3, the width W of the metal sheet 2 and the like) . For example, the former 16 as shown in FIG. 1 has an outer periphery that is rectangular in shape as viewed in an axial direction of the rotating shaft 16a (the vertical direction to the paper of FIG. 1), and the former 16 is formed into a rectangular cylindrical shape. The formers of the coils 101 to 104 as shown in FIGS. 4A to 4D have outer peripheries that are octagonal in shape as viewed in axial directions of the rotating shafts 16a, and the formers are formed into octagonal cylindrical shapes, respectively. The rotating shaft 16a of the former 16 is rotated by an electric motor 16c (see FIG. 2) serving as a drive unit. With drive of the motor 16c, the metal sheet 2 and the insulating sheet 3 are simultaneously rewound onto the former 16 thereby to be multi-layered.
The cooling ducts are provided in predetermined layers in the multi-layered metal sheet 2 (the insulating sheet 3) when the octagonal coils 102 to 104 are manufactured, for example. More specifically, for example, the duct 18 of each one of the coils 103 and 104 as shown in FIGS. 4C and 4D includes bar-shaped duct pieces 18a each made of an insulating material and a mount 18b serving as a mounting member. A plurality of duct pieces 18a is fixed to the mount 18b at predetermined intervals, so that the duct pieces 18a and the mount 18b are integrated with each other. The ducts 18 are fixed in duct insertion layers I set in the coils 103 and 104 by a fixing means, such as an adhesive agent, provided on the mount 18b during winding of the metal sheet 2 and the insulating sheet 3 onto the former 16, respectively. In the octagonally cylindrical coil 103, spaces for arrangement of the ducts 18 in the duct insertion layers I are defined in an upper side, a lower side, a right side and a left side in FIG. 4C, respectively. On the other hand, in the coil 104, spaces for arrangement of the ducts 18 in the duct insertion layer I are formed in upper and lower sides in FIG. 4D, respectively.
The spaces for arrangement of the ducts 18 are formed according to the shapes and dimensions of the ducts 18 so that the metal sheet 2 and the ducts 18 are brought into close contact with each other, as described above. As a result, a heat dissipation effect of the metal sheet 2 is improved. Further, each duct insertion layer I includes a part in which the duct 18 is not provided and the folding tendency is formed by the bending apparatus 15 so that a gap is prevented between layers of the metal sheet 2. Accordingly, even though arrangement spaces are defined for the ducts 18, the arrangement spaces (particularly, corners) can be prevented from resulting in drawback, with the result that the coils 103 and 104 are superior in a short-circuit mechanical force, namely, a mechanical force acting when short-circuit current flows, and the like.
A duct 19 of the coil 102 as shown in FIG. 4B is a corrugated duct formed into a corrugated form. The coil 102 has an arrangement space for the duct 19 in a duct insertion layer I formed throughout the periphery thereof. Since the arrangement space for the duct 19 is also formed according to the shape and dimensions of the duct 19, the coil 102 has a higher heat dissipation effect and can be rendered superior in mechanical characteristics. The ducts 18 having the bar-shaped duct pieces 18a may be arranged in the coil 102, instead of the corrugated duct 19. Thus, the shape and arrangement pattern of the ducts may be changed. Further, the whole coil may be formed into a rectangular cylindrical shape as the coil 1 in FIG. 3 or an octagonal cylindrical shape as the coils 101 to 104 in FIGS. 4A to 4D. Thus, the coil may be changed into a proper shape.
FIG. 2 is a block diagram showing an electrical arrangement of control system for manufacture of coils 1 and 101 to 104. The control device 20 is configured to be computer-centric and serves as a control unit including a CPU, a ROM, a RAM and a storage including a non-volatile memory. The control device 20 is connected to an operation input part 22 for inputting various operation signals from the encoder 14d and key switches on an operation panel, none of which are shown. The control device 20 is also connected to various detection sensors 23 including a detection sensor located close to the former 16 and detecting a wound sate of the metal sheet 2. For example, the detection sensor 23 may include a sheet detection unit which detects a winding start end of the metal sheet 2 and a thickness detection unit which detects the thickness of the metal sheet 2. Further, the control device 20 is connected to drive circuits 24, 25 and 26 driving the motor 14s for the feeder 14, the presser mechanism 17b and the motor 16c for the former 16 respectively.
The storage 21 stores coil information about the coils 1 and 101 to 104, duct information about the ducts 18 and 19, and the like. In the case of coil 1, for example, the coil information includes information about the thickness of the metal sheet 2 as well as the shape and dimensions in correspondence relationship with the former 16 (dimensions of a vertical longer side and a horizontal shorter side in FIG. 3) . The coil information is thus defined for every one of the coils 1 and 101 to 104. The duct information includes location information of installation space of each of coils 102 to 1004 as well as the dimensions of the ducts 18 and 19. The duct information is thus defined in correspondence relationship with the coil information. The coil and duct information may be set based on operation of the operation input part 22 by the operator as will be described in the description of the operation, and a thickness may be obtained from the detection sensor 23. The control device 20 controls the motors 14c and 16c and various actuators such as the presser mechanism 17b, based on the aforementioned information, so that the metal sheet 2 is automatically rewound onto the former 16 based on the aforementioned information.
The operation of the foregoing coil manufacturing apparatus will be described. The roll body 11 of the metal sheet 2 is attached to the attachment part 12a of the uncoiler 12. The winding termination end side of the roll body 11 is rewound to be set so as to be fed to the former 16 side through the leveler 13, the feeder 14 and the bending apparatus 15. The winding termination end of the roll body 11 serves as a winding start end when wound onto the former 16. Further, a roll body 11' of the insulating sheet 3 is attached to another attachment part 12a' to be set so as to be fed to the former 16 side from an uncoiler 12' .
The operator operates the operation input part 22 to select a type of the coils 1 and 101 to 104 to be manufactured or to set coil information and duct information. Upon operation of the start switch of the operation input part 22, the metal sheet 2 is rewound from the roll body 11 and the feeder 14 performs an intermittent feeding operation. In this case, the metal sheet 2 rewound from the roll body 11 is caused to pass between the upper and lower work rolls 13a and 13c, and 13b, so that internal distortion is eliminated and a winding tendency is corrected with the result that the metal sheet 2 becomes flat. Furthermore, the control device 20 calculates an amount of feed of the metal sheet 2 based on a detection signal of the encoder 14d detecting an amount of rotation of the motor 14c of the feeder 14, intermittently driving the motor 14c based on the coil information, so that a folding tendency is formed to correspond to a corner of the former 16 or a corner of the metal sheet 12 wound on the former 16.
The feed amount in the feed step will be described in detail with a concrete example. For example, when the coil 1 in FIG. 3 is manufactured, assume that the winding start end as shown by reference symbol "P0" in FIG. 3 is to be fixed to the corner of the former 16. Further, the former 16 formed into the rectangular shape as viewed in the axial direction has a shorter side dimension M1 and a longer side dimension M2, as shown in FIG. 1. In this case, the control device 20 supplies a drive signal to the motor 14c of the feeder 14 so that an amount L₁ of feed starting the winding start end P0 equals to the shorter dimension M1, based on the coil information. Subsequently, the control device 20 moves the presser mechanism 17b forward and backward to the bending die 17a side (a bending step) . As a result, a folded part serving as a folding tendency folded at 90° is formed at a location P1 spaced from the winding start end P0 by dimension M1 on the metal sheet 2 (see FIG. 3).
Further, the control device 20 drives the motor 14c so that a second feed amount L₂ equals to the longer side dimension M2 of the former 16 and thereafter, moves the presser mechanism 17b forward and backward. As a result, a folded part folded at 90° is formed at a location P2 spaced from the folded part P1 by dimension M2 on the metal sheet 2. Thus, the feed amounts L1, L2 and L3 of the feeder 14 are set to the shorter dimension M1, the longer dimension M2 and the shorter dimension M1 corresponding to the angles of the former 16 respectively, and a folding process is carried out every time the motor 14c is stopped, so that the plastically deformed folded parts P1, P2 and P3 are formed.
For example, the motor 16c for the former 16 driven to be synchronized with (tuned to) the motor 14c for the feeder 14. Accordingly, even when torque developed by the motor 16c is relatively smaller, the metal sheet 2 is rewound together with the insulating sheet 3 while adhering closely to the outer peripheral surface of the former 16, and no gaps are formed between the 90°-folded parts P1 to P3 and the corners of the former 16 respectively. The control device 20 drives the motor 14c based on the coil information, so that folded parts are formed at locations (L₄=M2+plate thickness) obtained by adding the plate thickness of the metal sheet 2 to M2, thereby setting the feed amount L₄ after the forming of the folded part P3.
The control device 20 subsequently sets feed amounts L₅, L₆, ... L_N, L_N+1 ... of the metal sheet 2 (and the insulating sheet 3) by the feeder 14 so that the metal sheet 2 rewound into lap winding with the insulating sheet 3 being interposed takes the form of an outer peripheral configuration of the former 16 (see FIG. 1) . More specifically, the control device 20 calculates feed amounts L5 and so on while allowing for a thickness of the already wound sheet materials 2 and 3, based on the coil information including the aforementioned dimensions M1 and M2 of the former 16 and the thickness of the metal sheet 2 (and the insulating sheet 3) . The bending process is sequentially carried out by the bending apparatus 15 according to the feed amounts L₅ and so on, so that the folded parts according to a rewinding amount by the former 16 are formed in the metal sheet 2 before the metal sheet 2 is rewound onto the former 16. As a result, as shown in FIG. 3, the multilayered coil 1 has a higher dimensional accuracy and a superior short-circuit mechanical force without occurrence of gaps between layers.
On the other hand, in manufacturing the coils 101 to 104 as shown in FIG. 4, an octagonal cylindrical former (not shown) is used, instead of the rectangular cylindrical former 16. Further, a bending die to form folded parts which are folded at 45° is used, instead of the bending die 17a to form the 90°-folded parts, although not shown in the drawings.
A manufacturing method of the coils 102 to 104 having cooling ducts will be described with the coil 104 in FIG. 4D being exemplified. More specifically, the differences between the above-described coil 1 and the coil 104 will be described.
The control device 20 once stops drive of the feeder 14 before the mount portions Ia and Ib of the duct insertion layers I (see FIG. 4D) in the metal sheet 2 are rewound into lap winding. In this case, the ducts 18 are manually mounted and fixed to the mount portions Ia and Ib (the mounting and fixing may be automatized) . The mount portions Ia an Ib on the metal sheet 2 are located at the former 16 side rather than the feeder 14 and bending apparatus 15 side, and the 45°-folded part can be identified as an index. Consequently, each duct 18 can accurately be mounted.
Subsequently, the control device 20 sets feed amounts of the metal sheet 2 so that installation spaces for the ducts 18 are defined in the upper and lower sides respectively as shown in FIG. 4D. Accordingly, since the folded parts are formed according to the shapes and dimensions of the ducts 18 so that the metal sheet 2 and the ducts 18 adhere closely to each other, the heat dissipation effect of the metal sheet 2 can be improved. As a result, as shown in FIG. 4D, the multilayered coil 104 has a higher dimensional accuracy and a superior short-circuit mechanical force without occurrence of gaps between layers.
Further, in the method of manufacturing any one of the coils 1, and 101 to 104, the control device 20 calculates the feed amount of the feeder 14 based on the coil information including the thickness of the metal sheet 2, the duct information and a rewinding amount of the former (the number of turns obtained from the size of the former and an accumulated value of feed amount, thereafter carrying out the bending process. As a result, a high precision determination of dimensions can be made.
As described above, the apparatus for manufacturing the coils 1 and 101 to 104 according to the embodiment includes the feeder 14 feeding to the former 16 side the metal sheet 2 unrolled by the unrolling unit, the bending apparatus 15 carrying out the bending process in which the metal sheet 2 fed out by the feeder 14 is bent before rewound onto the former 16, and the control device 20 controlling the bending process of the bending apparatus 15 based on the feed amount of the metal sheet 2 by the feeder 14, so that the winding start of the metal sheet 2 to be rewound onto the former 16 is shaped to conform to the outer peripheral configuration of the former 16 and thereafter to conform to the outer peripheral configuration of the metal sheet 2 to be rewound onto the former 16 into the lap winding. The bending tendency according to the winding amount of the metal sheet 2 by the former is imparted to the metal sheet 2 by the bending process control by the control device 20 before the metal sheet 2 is rewound onto the former 16.
According to this construction, the bending tendency according to the outer peripheral shape of the former 16 and the winding amount of the metal sheet 2 by the former 16 can be imparted to the metal sheet 2 before the metal sheet 2 is rewound onto the former 16. Accordingly, the rewound coils 1 and 101 to 104 can reliably be prevented from being bulged due to spring-back with the result that the dimensional accuracy can be improved. In this respect, when, differing from the method of the embodiment, the winding of the metal sheet onto the former cannot be carried out accurately, the sheet is displaced widthwise with the result of interrupt of the winding operation. According to the above-described construction, however, the metal sheet 2 can correctly be rewound onto the former 16 and can be prevented from displacement, with the result that the manufacturing efficiency and the quality of the metal sheet 2 can be improved.
The outer periphery of the former 16 has a polygonal shape as viewed in the axial direction of the rotating shaft 16a, and the bending apparatus 15 is configured to form a folding tendency on the metal sheet 2 corresponding to the corner of the former and subsequently, the corner of the metal sheet 2 to be wound onto the former 16 into the lap winding. According to this, even when the coils 1 and 101 to 104 are polygonal in shape, the corner can reliably be folded to a plastic area by the bending apparatus 15. Accordingly, the gaps between the layers at the corner can reliably be prevented with the result that high precision dimension determination can be made.
In particular, the coils 102 to 104 having the cooling ducts 18 or the cooling duct 19 are formed according to the shapes and dimensions of the ducts 18 and 19 so that the metal sheet 2 and the ducts 18 and 19 adhere closely to each other. This can improve the heat radiation effect of the metal sheet 2 and improve the short-circuit mechanical force and the like.
The feeder 14 and the bending apparatus 15 are disposed to be located near each other in the manufacturing apparatus. According to this, a forming error due to flexure of the metal sheet 2 can be prevented as much as possible and further improve the dimensional precision.
The leveler 13 is provided between the unrolling unit and the feeder 14 to correct the winding tendency of the metal sheet 2 unrolled by the unrolling unit. According to this, internal distortion can be eliminated by the leveler 13 and the winding tendency can be corrected with the result that the metal sheet 2 can be rendered flat. Consequently, the high precision coils 1 and 101 to 104 can stably be formed.
FIG. 5 illustrates a reference example. Identical or similar parts in the reference example are labeled by the same reference symbols as those in the foregoing embodiment. Description of the identical or similar parts will be eliminated and the differences between the first embodiment and the reference example will be described.
The former 30 in the reference example has an outer peripheral shape that is annular as viewed in the axial direction of the rotating shaft 16a and is cylindrical. The bending apparatus 31 serving as the bending unit includes a plurality of forming rolls 31a to 31c and is configured to form a curving tendency corresponding to a curvature of the former 30 or a curvature of the metal sheet 2 wound onto the former 30 into the lap winding.
More specifically, the storage 21 stores as coil information data of a feed amount of the metal sheet 2 and a curvature radius in correspondence relationship with the feed amount of the metal sheet 2 for every type of the former 30. The control device 20 changes positions of the forming rolls 31a to 31c (vertical positions, for example) as exemplified in FIG. 5 in conjunction with the feed amount of the metal sheet 2, based on the data of curvature radius. In this case, the positions of the forming rolls 31a to 31c are changed so that the metal sheet 2 is bent so as to conform to an outer configuration of the former 30 or an outer configuration of the metal sheet 2 wound onto the former 30 into the lap winding. The metal sheet 2 may continuously be fed by the feeder 14 (not shown in FIG. 5) disposed in the vicinity of the front side in the feeding direction of the bending apparatus 31. Alternatively, a servomotor driving any one of the forming rolls 31a to 31c or an encoder (neither shown) may be added so that the forming rolls 31a to 31c are driven while holding the metal sheet 2 between the rolls 31a and 31c, and the roll 31b by a predetermined pressure, with the result that the same function as the feeder 14 is achieved.
The leveler may be provided between the forming rolls 31a to 31c and the uncoiler 12 in the same manner as in the first embodiment in order that the internal distortion may be eliminated, although the leveler is not shown in FIG. 5.
In the above-described construction, the metal sheet 2 is rolled out of the roll body 11, and the feeder 14 (or the forming rolls 31a to 31c) is driven to perform continuous feeding. Since the metal sheet 2 is bent in the plastic area thereof by the forming rolls 31a to 31c in the bending step (and the feeding step), the internal distortion of the metal sheet 2 can be reduced.
The control device 20 controls the bending process by the forming rolls 31a to 31c based on the coil information, so that the curving tendency according to the cylindrical shape of the former 30 is imparted to the winding start of the metal sheet 2 before the winding start of the metal sheet 2 is wound onto the former 30. Accordingly, the metal sheet 2 is rewound onto the former 30 together with the insulating sheet 3 even when the torque of the motor 16 for the former 30 is small. Further, the control device 20 can calculate or correct the curvature radius according to the thickness of the metal sheet 2. The control device 20 carries out the control to adjust the positions of the forming rolls 31a to 31c, based on an amount of metal sheet 2 rewound onto the former 30. As a result, the bending process is carried out by the use of the forming rolls 31a to 31c so that the curvature radius of the metal sheet 2 is increased (the curvature is reduced) with an increase in the amount of metal sheet 2 wound onto the former 30. As a result, the cylindrical coil (see FIG. 5) wound into a multilayer has no gaps between the layers and has a higher dimensional accuracy and superior short-circuit mechanical force without occurrence of gaps between layers.
In the coil manufacturing apparatus according to the reference example, the bending apparatus 31 is configured to form the curving tendency corresponding to the curvature of the former 30 or the curvature of the metal sheet 2 rewound onto the former 30 into the lap winding. According to this, the curving tendency according to an amount of the metal sheet 2 rewound onto the former 30 can be imparted to the metal sheet 2 before the metal sheet 2 is rewound onto the former 30. Consequently, the cylindrical coil can reliably be prevented from being bulged due to spring-back with the result that the dimensional accuracy can be improved. Further, the metal sheet 2 can accurately by wound onto the former thereby to be prevented from being displaced, irrespective of the stiffness of the metal sheet 2, with the result that the cylindrical coil can be rendered superior in the manufacturing efficiency and quality. Thus, the reference example can achieve the same advantageous effect as the first embodiment.
The bending apparatus 31 in the reference example may be configured to have the function of the feeder as described above, or a feeder which is the same as the feeder 14 in the first embodiment may be disposed at a position near the input side of the bending apparatus 31.

Claims

A coil manufacturing apparatus which includes an unrolling unit (12) configured to unroll a band-shaped metal sheet (2) wound on a winding body (11) and a former (16) configured to rewind the metal sheet (2) while rotating the metal sheet (2),
a feeder (14) provided between the unrolling unit (12) and the former (16) to feed the metal sheet (2) unrolled by the unrolling unit (12), to the former (16) side, characterized by:
a bending unit (15) configured to carry out a bending process in which the metal sheet (2) fed by the feeder (14) is bent before the metal sheet (2) is wound onto the former (16), the bending unit (15) being configured to form a widthwise extending crease on the metal sheet (2), the crease corresponding to a corner of the former (16) or a corner of the metal sheet (2) lap-wound on the former (16);

a control unit (20) configured to control the bending process by the bending unit (15) based on a feed amount of the metal sheet (2) by the feeder (14) so that a winding start of the metal sheet (2) is shaped according to an outer peripheral shape of the former (16) and thereafter, according to an outer peripheral shape of the metal sheet (2) lap-wound onto the former (16), wherein:
the former (16) has an outer peripheral shape which is polygonal as viewed in an axial direction of a rotation axis thereof;

and the control unit (20) is configured to control the bending process by the bending unit (15) so that the crease according to a winding amount of the metal sheet (2) on the former (16) is imparted to the metal sheet before the metal sheet is wound onto the former.
The coil manufacturing apparatus according to claim 1, wherein the feeder (14) and the bending unit (15) are disposed in proximity to each other in the apparatus.
The coil manufacturing apparatus according to claim 1 or 2, further comprising a leveler (13) provided between the unrolling unit (12) and the feeder (14) to correct a winding tendency of the metal sheet (2) unrolled from the unrolling unit (12).
A method of manufacturing a coil, in which an unrolling unit (12) is provided for unrolling a band-shaped metal sheet (2) wound on a winding body (11) and the metal sheet (2) unrolled from the winding body (11) is rewound onto a former (16), the method comprising:
feeding the metal sheet (2) unrolled from the unrolling unit (12), to the former (16) side by a feeder (14) provided between the unrolling unit (12) and the former (16),

characterized by

bending the metal sheet (2) fed by the feeder (14) before the metal sheet (2) is wound onto the former (16), wherein:
the former (16) has an outer peripheral shape which is polygonal as viewed in an axial direction of a rotation axis thereof;

in the bending, a bending process is carried out in which a widthwise extending crease is formed on the metal sheet (2) so that a winding start of the metal sheet (2) is shaped according to an outer peripheral shape of the former (16) and thereafter, according to an outer peripheral shape of the metal sheet (2) lap-wound onto the former (16), the widthwise extending crease on the metal sheet (2) corresponding to a corner of the former (16) or a corner of the metal sheet (2) lap-wound on the former (16); and

the crease according to a winding amount of the metal sheet (2) on the former (16) is imparted to the metal sheet (2) by the bending process before the metal sheet (2) is rewound onto the former (16).
A coil configured by unrolling a band-shaped metal sheet (2) wound on a winding body (11) and rewinding the metal sheet (2) onto a former (16) having an outer peripheral shape which is polygonal as viewed in an axial direction of a rotation axis thereof,
characterized in that
a widthwise extending crease according to a winding amount of the metal sheet (2) on the former (16) has been imparted to the metal sheet (2) so that a winding start of the metal sheet (2) is shaped according to an outer peripheral shape of the former (16) and thereafter, according to an outer peripheral shape of the metal sheet (2) lap-wound onto the former (16), the widthwise extending crease on the metal sheet (2) corresponding to a corner of the former (16) or a corner of the metal sheet (2) lap-wound on the former (16), the crease impartment being carried out before the metal sheet (2) is rewound onto the former (16).