Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D28/00—Shaping by press-cutting; Perforating
  • B21D28/02—Punching blanks or articles with or without obtaining scrap; Notching
  • B21D28/22—Notching the peripheries of circular blanks, e.g. laminations for dynamo-electric machines
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D28/00—Shaping by press-cutting; Perforating
  • B21D28/02—Punching blanks or articles with or without obtaining scrap; Notching
  • B21D28/16—Shoulder or burr prevention, e.g. fine-blanking
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D35/00—Combined processes according to or processes combined with methods covered by groups B21D1/00 - B21D31/00
  • B21D35/002—Processes combined with methods covered by groups B21D1/00 - B21D31/00
  • B21D35/005—Processes combined with methods covered by groups B21D1/00 - B21D31/00 characterized by the material of the blank or the workpiece
  • B21D35/007—Layered blanks
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D39/00—Application of procedures in order to connect objects or parts, e.g. coating with sheet metal otherwise than by plating; Tube expanders
  • B21D39/03—Application of procedures in order to connect objects or parts, e.g. coating with sheet metal otherwise than by plating; Tube expanders of sheet metal otherwise than by folding
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D39/00—Application of procedures in order to connect objects or parts, e.g. coating with sheet metal otherwise than by plating; Tube expanders
  • B21D39/03—Application of procedures in order to connect objects or parts, e.g. coating with sheet metal otherwise than by plating; Tube expanders of sheet metal otherwise than by folding
  • B21D39/031—Joining superposed plates by locally deforming without slitting or piercing
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K1/00—Details of the magnetic circuit
  • H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
  • H02K1/22—Rotating parts of the magnetic circuit
  • H02K1/27—Rotor cores with permanent magnets
  • H02K1/2706—Inner rotors
  • H02K1/272—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis
  • H02K1/274—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets
  • H02K1/2753—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets the rotor consisting of magnets or groups of magnets arranged with alternating polarity
  • H02K1/276—Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM]
  • H02K1/2766—Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM] having a flux concentration effect
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K15/00—Methods or apparatus specially adapted for manufacturing, assembling, maintaining or repairing of dynamo-electric machines
  • H02K15/02—Methods or apparatus specially adapted for manufacturing, assembling, maintaining or repairing of dynamo-electric machines of stator or rotor bodies
  • H02K15/03—Methods or apparatus specially adapted for manufacturing, assembling, maintaining or repairing of dynamo-electric machines of stator or rotor bodies having permanent magnets
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K2201/00—Specific aspects not provided for in the other groups of this subclass relating to the magnetic circuits
  • H02K2201/09—Magnetic cores comprising laminations characterised by being fastened by caulking

Definitions

• the present disclosure relates to a process for the blanking of metal parts, in particular a multi-layer fine blanking process.
• the fine blanking process is, as such, generally known and are broadly applied in the manufacturing of metal parts, in particular for the cutting-out thereof from strip or plate shaped basic material.
• the known fine blanking process at least the 2D contour of the metal part is shaped by pressing a correspondingly shaped blanking punch against and through the basic material, which basic material is clamped between a blanking die and a blank holder of a blanking device.
• the blanking die and the blank holder thereto define a respective cavity that is shaped to accommodate the blanking punch.
• the fine blanking process is set apart from the more conventional blanking process, by the presence of the counter punch located opposite the blanking punch and pressing against the other side of the basic material as the blanking punch.
• a stack of three layers in particular composed of two metal strips with a third strip of insulating material there between, is fed to the blanking device and two mutually insulated rotor parts are subsequently blanked simultaneously from such layered basic material by the blanking punch.
• S57-156657 teaches to provide the layered basic material with protrusions that protrude through all three layers thereof, in a direction perpendicular to length direction of the strip.
• protrusions are provided for preventing the individual layers of the layered basic material from sliding relative to one another when it is intermittedly advanced in the blanking device in-between each blanking stroke.
• such known protrusions are each formed by bending an edge section of the layered strip downwards, which edge section is defined between two relatively closely spaced incisions into a side edge of the layered strip.
• the multi-layer blanking process is particularly relevant for the production of metal parts of relatively small thickness, such as individual lamina for an electric motor stator or rotor laminate, by using basic material of such small thickness.
• a production rate of the blanking process can be increased, essentially proportional to the number of layers that are applied in the layered basic material.
• the said multi-layer fine blanking process variant of the multi-layer blanking has been proposed recently in WO2017/174215 for handling even thinner metal parts, i.e. for handling even thinner layers of the basic material than what is possible with the conventional blanking process.
• the known layered basic material can be improved upon in view of the application thereof in the multi-layer fine blanking process.
• the known protrusions of the layered basic material may not perform as well in the fine blanking process as in the conventional blanking process.
• the present disclosure departs from and relies on the insight that the known protrusions provide an interlocking of the stacked layers, i.e. strips of the layered basic material in the plane of their main faces, but not perpendicular thereto.
• the known protrusions prevent the individual layers of the layered basic material from sliding relative to one another in the length and width directions thereof, but not from separating in their height, i.e. thickness direction.
• the present disclosure takes into account a particular feature of the fine blanking process, namely that after the metal part is cut by the blanking punch, the layered basic material and the blanking die are moved apart to create a gap between them, through which gap the metal parts are subsequently removed from the fine blanking device.
• the layered basic material is no longer supported in its height direction and, typically, also vibrations occur therein in that direction, e.g. due to the said intermitted advancement thereof.
• a mutual alignment of the individual layers of the layered basic material may not be optimally maintained as a consequence.
• the layered basic material is plastically deformed locally to create an interlock between the individual layers thereof in all of the length, width and height direction thereof, prior to the section of the layered basic material with such interlock is advanced to between the blanking die and the blank holder or between the blanking punch and counter punch of the fine blanking device.
• the interlocks are formed outside the virtual contour of the metal parts to be blanked from the basic material, which has the advantage that the mechanical and/or electrical properties of these metal parts are not deteriorated by the said plastic deformation associated with press-locking.
• a coating provided to the individual layers of the layered basic material such as an electrically isolating coating, is retained intact at the location of the metal parts.
• press-locking was surprisingly found to be suitable also for joining and interlocking three or more layers of sheet metal, provided that these layers have a combined thickness in the range from 0.2 mm to 1 .2 mm and that their individual thickness lies in the range from 0.1 mm to 0.3 mm and preferably does not exceed 0.2 mm.
• the known press-locking method requires a press-locking punch and an anvil that are located on opposite sides of the layered basic material and that are pressed together to plastically deform the layered basic material there between into an keyed connection that is referred to herein as the interlock.
• the known press-locking method has the advantage that the movement of the press-locking punch relative to the anvil, can be favourably coordinated with the movement of the blank holder or of the blanking punch relative to the blanking die, i.e. with the opening and closing of the blanking device.
• these relative movements are not only mutually coordinated but also jointly actuated.
• pressing joining can be advantageously integrated in the multi-layer fine blanking process, thus creating the novel multi-layer fine blanking process according to the present disclosure.
• a number of interlocks are created simultaneously, by using a number of simultaneously actuated pairs of press-locking punches and anvils. This has the advantage that the interlocking of the individual layers of the layered basic material is more stable without detriment to the production rate of the blanking process and/or blanking device.
• Figure 1 is a schematic, plan view of a typical blanked metal part, being a single lamina made from electrical steel for a stack of lamina, i.e. laminate, for a rotor of an electric motor;
• Figures 2A to 2F schematically illustrate a multi-layer blanking device and process for forming metal parts
• Figure 3 is a schematically drawn cross-section of a layered basic material used in the multi-layer blanking process, which layered basic material is provided with an interlock between the individual layers thereof;
• Figures 4A and 4B schematically illustrate a simplified press-locking device and process for interlocking the individual layers of the layered basic material
• Figure 5 is a schematically drawn perspective view of an alternative embodiment of the interlock between the individual layers of the layered basic material.
• Figure 6 is a schematic representation of a novel multi-layer blanking process including a process step of press-locking.
• Figure 1 provides an example of a metal part 10 that can suitably be produced with the aid of a blanking process, in particular the multi-layer blanking process discussed herein.
• the metal part 10 takes the form of an individual rotor disc 1 1 for a rotor laminate, i.e. stack of rotor discs of an electric motor.
• the rotor disc 1 1 is provided with a primary or central hole 12 and a number of secondary holes 13 that are arranged along its circumference.
• the outer contour, i.e. perimeter of the rotor disc 1 1 as well as the contours of the central and secondary holes 12, 13 thereof are formed, i.e. are cut out of a basic material, in particular electrical steel, either simultaneously in one cut, i.e.
• the central holes 12 of (the stack of) the rotor discs 1 1 accommodate a rotor shaft and the said secondary holes 13 thereof accommodate magnets.
• an electrically isolating layer is provided between the individual rotor discs 1 1 in the rotor stack in order to reduce so-called Eddy current losses, possibly in the form of an electrically isolating coating applied to at least one side of the basic material for the rotor discs 1 1 before blanking.
• the exact size or the exact contour of the rotor disc 1 1 illustrated in figure 1 is not relevant within the context of the present disclosure. Rather, the present disclosure is also applicable to not only differently shaped rotor discs 1 1 , but also the stator ring component (not illustrated) of the stator laminate of the electric motor and even to metal parts 10 in general, as long as these parts 1 1 are at least partly formed in the multi-layer fine blanking process that is described hereunder.
• the figures 2A-2F schematically illustrate a multi-layer blanking process for producing the rotor discs 1 1 or the metal part 10 in general.
• the figures 2A-2F each represent a simplified cross-section of the blanking device 90 that is used to cut-out such metal parts 10 from a layered basic material 51 comprising two or more (here: four) of mutually stacked layers, i.e. strips 50 of basic material.
• the blanking device 90 includes a blanking punch 30, a counter punch 40, a blank holder 70 and a blanking die 80.
• the blank holder 70 and the blanking die 80 each define a respective cavity 71 , resp.
• the blanking device 90 is shown in a first open state, wherein the blanking punch 30 is fully retracted into the blank holder 70, the counter punch 40 is fully retracted into the blanking die 80 and wherein the blank holder 70 and the blanking die 80 are separated from one another, at least sufficiently for allowing the layered basic material 51 to be inserted and/or advanced along its length direction relative to the blanking device 90, as schematically indicated by the dashed arrow.
• FIG 2B the blanking device 90 is shown after the blank holder 70 and the blanking die 80 have been moved towards each other to clamp the layered basic material 51 between them.
• FIG 2C the blanking device 90 is shown after the blanking punch 30 and the counter punch 40 have been moved towards each other to also clamp the layered basic material 51 between them.
• FIGS 2D and 2E the step of cutting out the metal part 10 from each strip 50 of the layered basic material 51 , by the forced movement of the combination of the blanking punch 30 and the counter punch 40 relative to the blanking die 80, is illustrated.
• the blanking device 90 is shown during such cutting-out and in figure 2E the blanking device 90 is shown after the metal parts 10 have been completely cut out, i.e. have been severed from the layered basic material 51 , but are still held between the blanking punch 30 and the counter punch 40.
• the blanking device 90 is shown in a second open state, wherein the blanking punch 30 is fully retracted into the blank holder 70 and wherein the counter punch 40 protrudes from the blanking die 80 after pushing the blanked metal parts 10 upwards out of the cavity 81 of the blanking die 80 to allow the extraction thereof from the blanking device 90. After such extraction, the blanking device 90 returns to its first open state shown in figure 2A etc.
• the individual strips 50 of the layered basic material 51 tend to separate from each other in their thickness direction, i.e. in the height direction H of the layered basic material 51 .
• the mutual alignment of the individual strips 50 in their length and width directions can become compromised, or at least the blanking device must be equipped with additional means (not illustrated) for supporting and guiding the layered basic material 51 when it is lifted from and/or advanced relative to the blanking die 80.
• the blanked metal parts 10 are extracted individually, or at least as individual, i.e. loose parts.
• the former multi-layer blanking process can be improved upon.
• a synchronising and a mutual alignment of the individual strips 50 of the layered basic material 51 can be favourably realised by mutually interlocking these strips 50 in all of the length, width and thickness directions thereof (i.e. in all 3 spatial/physical dimensions) by the local plastic deformation of the strips 50, i.e. by creating an interlock 1 there between by so-called press-locking, before the layered basic material 51 is inserted between the blanking punch 30 and the counter punch 40 of the blanking device 90.
• interlock 1 A possible embodiment of such interlock 1 is schematically illustrated in figure 3 in an enlarged cross-section of the layered basic material 51.
• the interlock 1 is essentially shaped as a dovetail-shaped joint 3 that is circularly symmetric, such that it prevents the strips 50 from relative movement in all three dimensions.
• FIG 4A and 4B an example of a press-locking method, in particular the press locking method for forming the interlock 1 of figure 3 is schematically illustrated.
• a first step of this particular press-locking method that is illustrated in figure 4A- the layered basic material 51 is inserted between a press-locking punch 101 with a projection 102 and an anvil 103 defining a hollow 104.
• the exact realization of the press-locking method is not relevant within the context of the present disclosure. Rather, the present disclosure relates to any press-locking method that realises a mutual interlocking of the individual layers/strips 50 of the layered basic material 51 in all three dimensions by the targeted, i.e. local and controlled plastic deformation thereof.
• a press-locking method is known that utilizes a planar anvil, in which case a ring is placed with some radial clearance around a press-locking punch.
• the basic material 51 plastically flows sideways and upward between the press-locking punch and the said ring, forming an annular bulge there between.
• the interlock 1 need not be formed with a circular symmetry, but may for example also be formed with a predominantly oval, square or rectangular, shape.
• a rectangular bulge 4 is formed by bending its short sides 6, whilst shearing- off its long sides 5.
• FIG 5 such rectangular interlock 1 is schematically illustrated in a cross section thereof.
• the relative movement of the individual layers 50; 50-T, 50-B in their thickness direction is blocked by the sheared long sides 5 of the bulge 4 at a top layer 50-T of the layered basic material 51 catching the sheared long sides 5 of a bottom layer 50-B of the layered basic material 51 .
• the layered basic material is illustrated with two individual layers/strips 50-T, 50- B, the illustrated rectangular interlock 1 is suitable for joining more than two layers/strips 50.
• the above-described press-locking methods are carried out as part of, i.e. as a process stage in the multi-layer fine blanking process.
• the first press-locking step (figure 4A) is synchronized with the first multi-layer fine blanking step (figure 2A)
• the second press-locking step (figure 4B) is preferably synchronized with the cutting of the metal parts 10 out of the layered basic material 51 (figure 2D).
• Such novel multi-layer blanking process including press-locking is schematically illustrated in figure 6 in relation to the rotor disc 1 1 illustrated in figure 1.
• two interlocks 1 (1 a, 1 b) are provided therein in a press-locking stage of the novel multi-layer blanking process.
• the interlocks 1 are transported together with the layered basic material 51 , by the said intermitted advancement thereof, to the blanking stage.
• the metal parts 10 that are depicted as rotor discs 1 1 in figure 6) are cut out of the layered basic material 51 , either entirely in one complete cut (not illustrated), or -depending on the complexity of the (contour of the) metal part 10- in two or more subsequent partial cuts.
• the central hole 12 and the secondary holes 13 of the rotor discs 1 1 are formed, where after, in a second partial cut, the outer circumference 14 of the rotor discs 1 1 is formed, whereby the rotor discs 1 1 are cut loose from the layered basic material 51 , leaving the space 15 therein.
• the individual layers 50 of the layered basic material 51 are favourably held together as one, by way of the interlocks 1 .
• the interlocks 1 are formed outside the outer circumference 14 of the metal parts 10 that thus favourably remain unaffected thereby.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Power Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Manufacture Of Motors, Generators (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (4)

Cited By (3)

Citations (7)

Family Cites Families (2)

• 2018
  • 2018-12-24 NL NL1043111A patent/NL1043111B1/en not_active IP Right Cessation
• 2019
  • 2019-12-24 WO PCT/EP2019/025484 patent/WO2020135926A1/en unknown
  • 2019-12-24 EP EP19835235.3A patent/EP3902640A1/en active Pending
  • 2019-12-24 JP JP2021537052A patent/JP7459110B2/ja active Active

Patent Citations (7)

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