JP2013121240A - Manufacturing method of rotor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a rotor capable of suppressing occurrence of weld.SOLUTION: The manufacturing method of a rotor includes the steps of: preparing a rotor core 7 having a plurality of slits 1 penetrating the rotating shaft 103 of a motor 101 in the axial direction; preparing an insert mold having a cavity 9 into which a magnet, supplied with a plastic resin from an injection molder as a binder, is introduced while passing through a plurality of gates 25, and inserting the rotor core 7 into the cavity 9; and leading a magnet 37 supplied from the injection molder from the plurality of gates 25 to both ends 27 of the plurality of slits 1, respectively.

Description

  The present invention relates to a method for manufacturing a rotor of an electric motor that generates a rotational force on a rotating shaft.

  FIG. 8 shows the rotating shaft 103, the rotor 105, the stator 107, and the housing 109 of the electric motor 101. The rotor 105 includes a rotor core 113 in which a plurality of slits 111 are formed, and a magnet 115 that is injection-molded in the plurality of slits 111. FIG. 9 shows a process in which the material of the magnet 115 supplied from the injection molding machine using a plastic resin as a binder is filled into the plurality of slits 111 via the spool 119, the runner 121, and the gate 123. Reference numeral 117 indicates a shaft hole through which the rotating shaft 103 is inserted. Illustration of an insert molding die into which the rotor core 113 is inserted is omitted.

  The material of the magnet 115 flowing into the slit 111 from the gate 123 branches in multiple directions inside the slit 111 and further merges. The boundary where two or more flows are in contact with each other is a weld. The material of the magnet 115 filled in the slit 111 is hardened and becomes a permanent magnet by being magnetized. However, the generation of welds near the both ends 125 of the slit 111 shown in FIG. 9 reduces the strength of the magnetic field. It is regarded as a problem in a remarkable point.

JP 2004-336831 A JP 2006-180677 A

  An object of the present invention is to provide a method for manufacturing a rotor capable of suppressing the occurrence of welds.

  The present invention provides a step of preparing a rotor core having a plurality of slits having both ends close to the outer peripheral surface and having a central portion separated from the outer peripheral surface, and extending in the axial direction of the rotating shaft of the motor, and an injection molding machine A magnet supplied with a plastic resin as a binder passes through a plurality of gates and prepares an insert mold to be introduced into a cavity, and the rotor core is inserted into the cavity; and the injection molding machine supplies the magnet. And a step of guiding the magnet from the plurality of gates to both ends of the plurality of slits.

  In the present invention, the plurality of slits are arranged at intervals in the direction in which the rotation shaft rotates, and a magnet supplied from the injection molding machine is directed between the plurality of slits from the gate. It is characterized by introducing.

  Further, in the present invention, the rotor core has an end face in the axial direction, and a region adjacent to the end face of the cavity of the insert mold is extended from the plurality of gates to both ends of the plurality of slits. A groove portion for introducing a magnet supplied from the injection molding machine is used.

  Further, the present invention is characterized in that one or more slits arranged in the radial direction of the rotating shaft with respect to the individual slits are formed in the rotor core.

  In the present invention, the plurality of slits are formed in an arc shape in which both ends are directed outward in the radial direction, and the region of the cavity circulates around the plurality of slits to form the plurality of slits. It is characterized by a ring shape that intersects both ends.

  According to the method for manufacturing a rotor of the present invention, a magnet material (hereinafter simply referred to as “magnet”) supplied from an injection molding machine is guided from a plurality of gates of an insert mold to both ends of a plurality of slits. As a result, the magnets form two flows from both ends of each slit toward the inside of the slit. Since the flow of these magnets does not touch each other in the vicinity of both ends of the slit, the generation of welds in the vicinity of both ends of the slits is suppressed, and the decrease in the magnetic field strength due to the welds is prevented. A decrease in magnetic force can be prevented.

  In particular, when a plurality of slits are spaced apart from each other in the direction in which the rotation shaft rotates, according to the method for manufacturing a rotor of the present invention, the magnet is introduced from the gate toward the plurality of slits. can do. Thereby, since the flow of the two magnets which goes to the inside of the slit from both ends of each slit is formed, the manufacturing method of the rotor of the present invention can achieve the above effect.

  In the rotor manufacturing method of the present invention, the region adjacent to the end face of the cavity of the insert mold is used as a groove for introducing magnets from the plurality of gates to both ends of the plurality of slits. There is an effect that the pressures or densities of the magnets filled in are equal to each other. As a result, the rotor manufacturing method of the present invention makes it possible to manufacture a rotor capable of generating the desired magnetic field by making the properties of the magnets filled in the plurality of slits uniform.

  In the rotor manufacturing method of the present invention, when one or more slits are arranged in the radial direction of the rotating shaft for each slit, the properties of the magnets filled in all the slits are made uniform and desired. It is possible to manufacture a rotor that can generate a magnetic field.

  In addition, the plurality of slits are formed in an arc shape in which both ends are directed outward in the radial direction, and the cavity region is formed in an annular shape that circulates around the plurality of slits and intersects both ends of the plurality of slits. In this case, the magnet supplied from the injection molding machine to the cavity region flows into both ends of all the slits. For this reason, since the flow of the two magnets which goes to the inside of the slit from both ends of each slit is formed, the above effect can be achieved according to the method for manufacturing a rotor of the present invention.

Sectional drawing which shows the usage example of the insert metal mold | die applied to the manufacturing method of the rotor which concerns on Example 1 of this invention. Sectional drawing of the stationary metal mold | die of the insert metal mold | die applied to the manufacturing method of the rotor which concerns on Example 1 of this invention. (A) is a front view of the fixed mold of the insert mold used for manufacture of the rotor which concerns on Example 1 of this invention, (b) is a front view of the modification. Sectional drawing of the rotor which concerns on Example 1 of this invention. The perspective view which shows the principal part of the rotor which concerns on Example 1 of this invention. (A) is a front view of the fixed mold of the insert mold used for manufacture of the rotor which concerns on Example 2 of this invention, (b) is a front view of the modification. The perspective view which shows the principal part of the rotor which concerns on Example 2 of this invention. Sectional drawing of an electric motor provided with the rotor of a prior art example. Sectional drawing which shows the process of manufacturing the rotor of a prior art example.

  A method for manufacturing a rotor according to an embodiment of the present invention will be described. It is assumed that the same designations are used for the elements already described as conventional techniques regardless of whether or not they are illustrated. Further, the axial direction, radial direction, and rotational direction described below are based on the rotational axis of the electric motor.

  FIG. 1 shows a rotor core 7 having a plurality of slits 1 extending in the axial direction and having both end faces 3 and 5 in the axial direction, and an insert mold 11 in which the rotor core 7 is inserted into a cavity 9. ing. The insert molding die 11 includes a fixed die 13 that is fixed to the injection molding machine, and a movable die 15 that is advanced and retracted in the axial direction with respect to the fixed die 13. As shown in FIGS. 1 and 2, the fixed mold 13 is formed with a groove portion 17 that is recessed with respect to the end surface 3 of the rotor core 7 at the back end of the cavity 9, and this groove portion 17 is formed on one end surface of the rotor core 7. 3 is an adjacent region. In the movable mold 15, a groove portion 19 that is recessed with respect to the end surface 5 of the rotor core 7 is formed at the back end of the cavity 9, and this groove portion 19 is a region adjacent to the other end surface 5 of the rotor core 7.

  Hereinafter, unless otherwise specified, the drawings refer to FIGS. 1 and 2, and the insert molding die 11 with the rotor core 7 inserted into the cavity 9 will be described. Moreover, since the form of the cavity 9 of the movable mold 15 is the same as that of the fixed mold 13 except that the spool 21, the runner 23, and the gate 25 are formed in the fixed mold 13, the movable mold 15 Note that the cavity 9 of the fixed mold 13 is not shown.

  FIG. 3A is a front view of the fixed mold 13 of the insert molding mold 11 as seen in the direction of the arrow of the AA line in FIG. The four groove parts 17 which showed the space | interval are shown. FIG. 3B shows a modification thereof. A plurality of slits 1 of the rotor core 7 and imaginary lines representing the shaft holes 117 are overlapped in the same figure.

  The rotor core 7 is obtained by laminating a plurality of core sheets made of a ferromagnetic material in the axial direction. As shown in FIG. 3A, the slit 1 is an arc-shaped opening having its both ends 31 and 33 directed outward in the radial direction. Further, the central portion 34 of the slit 1 is separated from the outer peripheral surface 8 of the rotor core 7 shown in FIGS. Four ranges 29 are assigned to the end faces 3 and 5 in the axial direction of the rotor core 7 at an equal angle of 90 ° around the rotation axis, and one (single layer) slit 1 is opened in each range 29. ing. The groove portion 17 extends so as to intersect one end 31 of both ends of the slit 1 formed in each area 29 and one end 33 of both ends of the slit 1 formed in the area 29 adjacent thereto. Yes. Gates 25 are opened in the respective groove portions 17, and the individual gates 25 are arranged between the plurality of slits 1 formed in the ranges 29 adjacent to each other.

  Furthermore, one or more slits arranged in the radial direction with respect to the slits 1 of the individual ranges 29 may be formed in the rotor core 7. That is, as shown in FIG. 3B, the groove portion 17 includes a plurality of (multilayer) slits 1 formed in the individual areas 29, and a plurality of slits 1 formed in the areas 29 adjacent thereto. It may extend so as to intersect with one end 33 of each slit 1.

  An injector of an injection molding machine is brought into contact with the spool 21 of the insert molding die 11. A magnet material (hereinafter simply referred to as “magnet”) using a plastic resin supplied from the injector as a binder passes through the runner 23 and the gate 25 and reaches the groove portion 17 of the fixed mold 13. As shown in FIGS. 3A and 3B, since the gate 25 is disposed between the two adjacent slits 1, the magnet moves from the gate 25 to the groove 17 toward the plurality of slits 1. It is introduced and flows into both ends 31 and 33 of each slit 1. As a result, as shown in FIG. 4, the magnets 37 are filled in the plurality of slits 1 of the rotor core 7, and the grooves 17 and 19 are filled with the magnets 37.

  Waiting for the magnet 37 to harden, the insert molding die 11 is opened, and the rotor 39 shown in FIG. The magnet that fills the grooves 17 and 19 serves as the holding member 41. Subsequently, by magnetizing the magnets 37 filled in the plurality of slits 1 of the rotor 39, a desired magnetic field can be generated in the rotor 39. The holding member 41 can play a role of restricting the magnet 37 from being carelessly detached from the inside of the slit 1 in the axial direction. The dimensions of each part of the rotor 39 and the ratio thereof are arbitrarily set design items, and the height of the holding member 41 protruding from the end face 3 of the rotor core 7 is exaggerated in the drawing. Reference numeral 43 indicates the core sheet.

  As described above, the magnets flowing into the slit 1 are directed inward from the both ends 31 and 33 of the individual slits 1 as indicated by arrows f and f ′ in FIGS. Two streams are formed. Since the flow of these magnets does not contact each other in the vicinity of both ends 31 and 33 of the slit 1, the generation of welds in the vicinity of both ends 31 and 33 of the slit 1 is suppressed, and the strength of the magnetic field is reduced by the welds. Can be prevented.

  Usually, the demagnetization resistance of the magnet filled in the slit 1 tends to be weak at both ends 31 and 33 near the outer peripheral surface 8 of the rotor core 7. By preventing the occurrence of welds in the vicinity of both ends 31 and 33 having a weak demagnetizing force, it is possible to effectively prevent a decrease in the demagnetizing force of the entire magnet filled in the slit 1. Further, the demagnetization resistance of the magnet filled in the slit 1 is the strongest in the vicinity of the central portion 34 of the slit 1 away from the outer peripheral surface 8 of the rotor core 7. For this reason, positioning the weld in the central portion 34 of the slit 1 is advantageous in suppressing a decrease in demagnetization resistance due to the weld. In particular, when the stator is concentrated winding, the effect is remarkable.

  Moreover, the groove parts 17 and 19 have the effect | action which makes the pressure or the density of the magnet 37 with which the several (multilayer) slit 1 is filled mutually equal. Thereby, the property of the magnet 37 with which the some slit 1 is filled can be made uniform, and a desired magnetic field can be generated in the rotor 39 manufactured by the above method.

  6A and 6B show a circular groove portion 17 formed along the inner peripheral surface of the cavity 9. The groove portion 17 intersects both ends 27 of all the slits 1, and the gate 25 is disposed between both ends 27 of each slit 1, so that the magnet supplied from the injection molding machine to the gate 25 is from the gate 25. It flows into the both ends 27 of each slit 1 first. As a result, as shown by arrows f and f ′, two flows are formed from both ends 27 of each slit 1 toward the inside of the slit 1.

  FIG. 7 shows a rotor 39 in which the holding member 41 is formed by the groove 17 shown in FIG. 6A and the plurality of slits 1 are filled with magnets 37. Other configurations and effects are the same as those of the first embodiment. According to this embodiment, since the holding member 41 is rotationally symmetric, the windage loss when the rotor 39 rotates is reduced. Moreover, the rotor 39 implement | achieves the highly efficient electric motor which can use not only a magnet torque but a reluctance torque as an element which comprises a permanent magnet embedded synchronous motor. Further, when a large number of slits 1 are provided in the radial direction, the rotor 39 realizes a low-cost and high-efficiency electric motor as an element constituting a magnet auxiliary-use type synchronous reluctance motor.

  It should be noted that the present invention can be carried out in a mode in which various improvements, modifications, or variations are added based on the knowledge of those skilled in the art without departing from the spirit of the present invention. The shape of the slit 1 is not limited to an arc shape, and may be a linear shape. The material of the magnet, the material of the rotor core 7, and the use of the electric motor including the rotor 39 do not characterize the present invention.

  Further, the holding member 41 is not necessarily formed on both end surfaces 3 and 5 of the rotor core 7. It is not necessary for the groove portions 17 and 19 of one insert mold to have the same form. Two types of groove portions 17 and 19 selected from a plurality of shapes of the groove portions 17 and 19 described in the first and second embodiments are respectively provided in a fixed die 13 and a movable die 15 of one insert die. It may be formed.

  The present invention may be applicable to an electric motor that drives a compressor or the like of an air conditioner.

  1, 111 ... slit, 3, 5 ... end face, 7, 113 ... rotor core, 8 ... outer peripheral surface, 9 ... cavity, 11 ... insert mold, 13. .. Fixed mold, 15 ... Moveable mold, 17,19 ... Groove, 21,119 ... Spool, 23,121 ... Runner, 25,123 ... Gate, 27,125. .. Both ends, 29 ... range, 31, 33 ... one end, 34 ... center, 37, 115 ... magnet, 39, 105 ... rotor, 41 ... holding member, 43. .. Core sheet, 101 ... Electric motor, 103 ... Rotating shaft, 107 ... Stator, 109 ... Housing, 117 ... Shaft hole.

Claims (5)

A step of preparing a rotor core having a plurality of slits having both ends close to the outer peripheral surface and having a central portion away from the outer peripheral surface penetrating in the axial direction of the rotating shaft of the electric motor;
Preparing an insert mold in which a magnet supplied as a binder from an injection molding machine passes through a plurality of gates and being introduced into a cavity, and inserting the rotor core into the cavity;
A method of manufacturing a rotor, comprising: a step of guiding magnets supplied from the injection molding machine to both ends of the plurality of slits from the plurality of gates.   The plurality of slits are arranged to be spaced apart from each other in a direction in which the rotation shaft rotates, and a magnet supplied from the injection molding machine is introduced from the gate toward the slits. The method for manufacturing a rotor according to claim 1.   The rotor core has an end face in the axial direction, and an area adjacent to the end face of the cavity of the insert mold is supplied from the injection molding machine to both ends of the plurality of slits from the plurality of gates. The rotor manufacturing method according to claim 1, wherein the groove is configured to introduce a magnet to be used.   The rotor production according to any one of claims 1 to 3, wherein one or more slits arranged in a radial direction of the rotating shaft with respect to each of the slits are formed in the rotor core. Method.   The plurality of slits are arcuate with both ends facing outward in the radial direction, and the cavity region circulates around the plurality of slits and intersects each end of each of the plurality of slits. The method for manufacturing a rotor according to claim 1, wherein the rotor has a ring shape.

Images