Rotor punching sheet and forming method thereof, rotor iron core, servo motor and robot

Abstract

The invention provides a rotor punching sheet and a forming method thereof, a rotor core, a servo motor and a robot. The rotor punching sheet comprises a punching sheet body (1), the punching sheet body (1) is provided with a rotor outer circle (2), and under one pole, the rotor outer circle (2) of the punching sheet body (1) is provided with a groove (3) recessed inwards relative to the rotor outer circle (2) and / or a protrusion (4) protruding outwards relative to the rotor outer circle (2). According to the rotor punching sheet, the outer contour punching precision of the rotor punching sheet can be improved, the cogging torque and torque pulsation of the motor are reduced, and the positioning precision of a robot is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of robots, and in particular to a rotor punching sheet and a forming method thereof, a rotor core, a servo motor and a robot. Background Art

[0002] In the design and manufacturing of servo motors, the accuracy of the rotor core is one of the key factors that determine the performance of the motor. This accuracy is mainly determined by the material properties, mold design and stamping process parameters during the stamping process. The thickness of the electromagnetic steel sheet is generally between 0.2mm and 1mm, showing the characteristics of thinness, lightness and high efficiency, which is very suitable for manufacturing high-speed rotating motor parts. However, it is precisely because of its thin and thick characteristics that the steel sheet is extremely susceptible to mold stress during the stamping process, especially in the shaping stage of the complex shape of the rotor core, such as the formation of sharp angles, curves or irregular shapes, which makes dimensional control a major challenge.

[0003] Ideally, when the outer contour of the servo motor's rotor core fully meets the design dimensions, the air gap flux density waveform of the motor should present a perfect sine wave. This is because the sinusoidal flux density distribution can ensure uniform distribution of the magnetic field inside the motor, effectively reduce cogging torque and torque pulsation, and thus improve the efficiency and operating stability of the motor. Cogging torque is generated when the motor is in the no-load state due to the unevenness of the magnetic circuit between the stator and the rotor, which will affect the starting performance and running stability of the motor; while torque pulsation will cause fluctuations in power output when the motor is running, affecting the overall control accuracy.

[0004] However, when the outer contour dimensional accuracy of the rotor core decreases, that is, it deviates from the ideal design value, the air gap flux waveform of the motor will be significantly distorted. This distortion will cause additional harmonic components to appear in the waveform, which greatly increases the harmonic content. The increase in harmonic content directly leads to an increase in cogging torque and torque pulsation, and ultimately reduces the positioning accuracy of the robot. Summary of the invention

[0005] The main purpose of the present invention is to provide a rotor punching sheet and its forming method, a rotor core, a servo motor and a robot, which can improve the stamping accuracy of the outer contour of the rotor punching sheet, reduce the motor tooth torque and torque pulsation, and improve the positioning accuracy of the robot.

[0006] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, a rotor punching sheet is provided, including a punching sheet body, the punching sheet body having a rotor outer circle, and under one pole, a groove recessed inwardly relative to the rotor outer circle and / or a protrusion protruding outwardly relative to the rotor outer circle is provided on the rotor outer circle of the punching sheet body.

[0007] Furthermore, the protrusion or groove has two endpoints at both ends along the circumferential direction, and the angle formed by the line connecting the two endpoints and the center of the punch body is γ, 1°≤γ≤70 / P°, where P is the number of rotor poles.

[0008] Furthermore, the angle between the d-axis and the line connecting the end point of the protrusion or groove close to the d-axis and the center of the punch body is α, 20° / P≤α≤80° / P, where P is the number of rotor poles.

[0009] Furthermore, the diameter of the outer circle of the rotor is Ф. When a protrusion is set on the outer circle of the rotor, the maximum diameter of the circle where the point on the outer contour of the protrusion is located with the center of the punch body as the center of the circle is ФC1, Ф<ФC1≤Ф+2 / 3*δ, where δ is the air gap width; when a groove is set on the outer circle of the rotor, the minimum diameter of the circle where the point on the outer contour of the groove is located with the center of the punch body as the center of the circle is ФC2, Ф-2 / 3*δ≤ФC2<Ф, where δ is the air gap width.

[0010] Further, the protrusion or the groove is located between the d-axis and the q-axis.

[0011] Furthermore, the protrusion or the groove is formed by connecting a plurality of straight line segments in sequence; or, the protrusion or the groove is formed by connecting a plurality of arc line segments in sequence; or, the protrusion or the groove is formed by connecting a plurality of straight line segments and arc line segments in sequence.

[0012] Further, when the number of protrusions and / or grooves is an even number, the protrusions and / or grooves are evenly distributed on both sides of the d-axis.

[0013] According to another aspect of the present invention, there is provided a method for forming the above-mentioned rotor punching sheet, comprising:

[0014] Punching magnetic steel slots;

[0015] Punching the inner circle of the rotor;

[0016] Punching the outer circle of the rotor, wherein the outer circle of the rotor is discontinuously separated from the residual material along the circumferential direction, and the rotor punching is connected to the residual material at the protrusions and / or grooves;

[0017] Punching is performed at the protrusions or grooves to disconnect the rotor punching sheet from the remaining material and form the rotor punching sheet.

[0018] According to another aspect of the present invention, a rotor core is provided, comprising a plurality of rotor punchings stacked in the axial direction, wherein the rotor punchings are the above-mentioned rotor punchings.

[0019] According to another aspect of the present invention, a servo motor is provided, comprising a rotor core, wherein the rotor core is the above-mentioned rotor core.

[0020] According to another aspect of the present invention, there is provided a robot comprising the above-mentioned rotor core or the above-mentioned servo motor.

[0021] According to the technical solution of the present invention, the rotor punching sheet includes a punching sheet body, the punching sheet body has a rotor outer circle, and under one pole, a groove that is recessed inward relative to the rotor outer circle and / or a protrusion that protrudes outward relative to the rotor outer circle is provided on the rotor outer circle of the punching sheet body. The rotor punching sheet is provided with a groove and / or a protrusion on the rotor outer circle, and a connection structure can be formed by using the groove or the protrusion during the punching process of the rotor punching sheet, so that the rotor punching sheet is divided into two steps when punching the rotor outer circle. When punching the rotor outer circle, the position of the groove or the protrusion is still connected, and only the structure of the rotor outer circle is punched. At this time, the connection effect of the groove or the protrusion can play a positioning role in the punching process of the rotor outer circle, so that the machining accuracy and dimensional accuracy of the rotor outer circle can be guaranteed, and the dimensional accuracy of the rotor outer circle can be avoided from being reduced due to the influence of the stamping stress, the distortion of the air gap magnetic flux waveform is reduced, the harmonic content is greatly reduced, the motor cogging torque and torque pulsation are reduced, and the positioning accuracy of the robot is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0023] Figure 1 A schematic diagram showing the structure of a motor in the related art is shown;

[0024] Figure 2 A schematic diagram showing the structure of a rotor core in the related art is shown;

[0025] Figure 3 Shows Figure 2 Schematic diagram of the enlarged structure at A;

[0026] Figure 4 A schematic diagram showing a punching process of a rotor punching sheet in the related art is shown;

[0027] Figure 5 The air gap magnetic flux waveform of the motor when the outer contour of the rotor in the related art is not deformed is shown;

[0028] Figure 6 The air gap flux density waveform of the motor when the outer contour of the rotor is deformed in the related art is shown;

[0029] Figure 7 A schematic diagram showing the structure of a rotor punching sheet according to an embodiment of the present invention is shown;

[0030] Figure 8 Shows Figure 7Schematic diagram of the enlarged structure at B;

[0031] Fig. 9 A schematic diagram showing the structure of a rotor punching sheet according to an embodiment of the present invention is shown;

[0032] Fig.10 Shows Fig. 9 Schematic diagram of the enlarged structure at C;

[0033] Fig.11 A schematic diagram of a punching process of a rotor punching sheet according to an embodiment of the present invention is shown;

[0034] Fig.12 A schematic diagram of a punching process of a rotor punching sheet according to an embodiment of the present invention is shown;

[0035] Fig.13 A dimensional structure diagram of a rotor punching according to an embodiment of the present invention is shown;

[0036] Fig.14 Shows Fig.13 Schematic diagram of the enlarged structure at D;

[0037] Fig.15 A dimensional structure diagram of a rotor punching according to an embodiment of the present invention is shown;

[0038] Fig.16 Shows Fig.15 Schematic diagram of the enlarged structure at E;

[0039] Fig.17 The graph showing the effect of γ on the motor cogging torque;

[0040] Fig.18 A graph showing the effect of α on the motor cogging torque is shown;

[0041] Fig.19 The graph showing the effect of ФC1 on the motor cogging torque;

[0042] Fig. 20 The graph showing the effect of ФC2 on the motor cogging torque;

[0043] Fig.21 A schematic diagram showing the structure of a rotor punching sheet according to an embodiment of the present invention is shown;

[0044] Fig. 22 Shows Fig.21 Schematic diagram of the enlarged structure at G;

[0045] Fig.23 A schematic diagram showing the structure of a rotor punching sheet according to an embodiment of the present invention is shown;

[0046] Fig.24 Shows Fig.23 Schematic diagram of the enlarged structure at H;

[0047] Fig.25 A schematic diagram showing the structure of a rotor punching sheet according to an embodiment of the present invention is shown;

[0048] Fig.26 Shows Fig.25 Schematic diagram of the enlarged structure at F;

[0049] Fig. 27 A schematic diagram showing the structure of a rotor punching sheet according to an embodiment of the present invention; and

[0050] Fig.28 Shows Fig. 27 Schematic diagram of the enlarged structure at I.

[0051] The above drawings include the following reference numerals:

[0052] 1. Punching sheet body; 2. Outer circle of rotor; 3. Groove; 4. Protrusion; 5. Inner circle of rotor; 6. Magnetic steel slot; 11. Air gap; 12. Stator core; 13. Coil winding; 14. Rotor core; 15. Magnetic steel; 21. First arc segment; 22. Second arc segment; 23. Third arc segment. DETAILED DESCRIPTION

[0053] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0054] like Figures 1 to 3 As shown, the servo motor in the related art includes a stator core 12 and a rotor core 14. The stator core 12 is sleeved outside the rotor core 14 and forms an air gap 11 with the rotor core 14. The radial width of the air gap 11 is δ. The stator core 12 is provided with stator wire slots, and the stator wire slots are provided with coil windings 13. The rotor core 14 is provided with magnetic steel slots 6, and the magnetic steel 15 is provided in the magnetic steel slots 6. The diameter of the largest circle formed by taking the outer contour of the rotor core 14 as a point on the circle and the center of the rotor core 14 as the center of the circle is Φ. The outer contour of the rotor core 14 forms the rotor outer circle 2 of the rotor core 14. In order to make the waveform of the air gap magnetic density more convenient to form a sine wave, it is generally necessary to modify the structure of the rotor outer circle 2, such as Figure 3 As shown, under one pole, the rotor outer circle 2 includes a first arc segment 21, a second arc segment 12 and a third arc segment 13 connected in sequence, and the three arc segments can adjust the air gap between the rotor core 14 and the stator core 12, so as to be more conducive to making the waveform of the air gap magnetic flux density form a sine wave. In some embodiments, under one pole, the rotor outer circle 2 can also adopt an arc. The rotor core 14 also has a rotor inner circle 5.

[0055] When the motor is powered on, the electrical energy is converted into a magnetic field, namely the armature magnetomotive force, through the stator winding. This magnetomotive force interacts with the permanent magnet magnetomotive force generated by the permanent magnets on the rotor to generate electromagnetic force, drive the rotor to rotate, and then generate output torque and output power. The output torque is the ability of the motor to generate rotational motion, while the output power reflects the mechanical energy that the motor can output per unit time.

[0056] The rotor is the component that generates permanent magnet magnetomotive force. The design structure and dimensional accuracy of the rotor have a direct and significant impact on the electromagnetic performance of the motor. The magnetic field distribution of the motor can be optimized by designing the arrangement and shape of the magnetic steel inside the rotor, thereby affecting the power density, efficiency and cogging torque of the motor.

[0057] The magnetic steel radially embedded rotor core structure of the servo motor in the related art is as follows Figure 2 and Figure 3 As shown, the rotor core 14 is composed of magnetic steel slots 6, rotor inner circle 5 and rotor outer circle 2. The outer contour of each pole rotor is composed of 1 or 3n (n is an integer) arc or straight line segments. The rotor core 14 is formed by stacking rotor punchings made of multiple electromagnetic steel sheets through multiple processes of a stamping die. The rotor punching process in the related art is as follows: Figure 4 As shown, magnetic steel slots are punched out on the electromagnetic steel sheets in sequence, i.e., the inner circle of the rotor, and the outer circle of the rotor. Finally, the rotor punching sheets are blanked into the lamination cavity for lamination to form the rotor core 14. The thickness of the rotor punching sheets is generally 0.2mm-1mm, which is relatively thin. During the die stamping process, the complex outer contour of the rotor punching sheets will lead to poor dimensional accuracy of the final molding due to the influence of the stamping stress. When the outer contour of the rotor punching sheets is the ideal design size, according to the principle of electromechanics, the air gap magnetic flux waveform is an ideal sine wave, such as Figure 5 When the stamping accuracy of the rotor outer contour is poor and the size deviates from the ideal value, the air gap magnetic flux waveform will be greatly distorted, such as Figure 6 As shown in the figure, the harmonic content increases significantly, which eventually leads to an increase in the motor cogging torque and torque ripple, and reduces the positioning accuracy of the robot.

[0058] In order to solve the above problems, refer to Figures 7 to 28 As shown, according to an embodiment of the present invention, the rotor punching includes a punching body 1, which has a rotor outer circle 2. Under one pole, the rotor outer circle 2 of the punching body 1 is provided with a groove 3 that is recessed inward relative to the rotor outer circle 2 and / or a protrusion 4 that protrudes outward relative to the rotor outer circle 2.

[0059] The rotor punching sheet is provided with grooves 3 and / or protrusions 4 on the rotor outer circle 2, and the grooves 3 or protrusions 4 can be used to form a connecting structure during the punching process of the rotor punching sheet, so that the rotor punching sheet is divided into two steps when punching the rotor outer circle 2. When punching the rotor outer circle 2, the connection is still maintained at the position of the grooves 3 or protrusions 4, and only the structure of the rotor outer circle 2 is punched. At this time, the connecting effect of the grooves 3 or protrusions 4 can play a positioning role in the punching process of the rotor outer circle 2, so that the processing accuracy and dimensional accuracy of the rotor outer circle 2 can be guaranteed, and the dimensional accuracy of the rotor outer circle 2 is avoided from being reduced due to the influence of the stamping stress, the distortion of the air gap magnetic density waveform is reduced, the harmonic content is greatly reduced, the motor tooth torque and torque pulsation are reduced, and the robot positioning accuracy is improved.

[0060] The conventional forming process of motor rotor punching sheets is usually one-step forming, that is, during the punching process, all outer contours of the punching sheets are separated from the residual material at the same time. This method is prone to dimensional deviation due to the uneven distribution of punching stress. In this embodiment, by providing the groove 3 and / or the protrusion 4 on the rotor outer circle 2, the rotor punching sheet can adopt a step-by-step forming process, firstly separating the rotor outer circle from the residual material, but by maintaining the connection between the rotor punching sheet and the residual material at the protrusion or groove position, the rotor outer circle can be provided with additional connection positioning during the forming process, reducing deformation during the punching process, thereby improving the dimensional accuracy of the rotor outer circle.

[0061] In the early stage of rotor punching, maintaining the connection between the rotor punching and the residual material, especially at the position where the protrusion or groove is set, can make the punching more stable during the punching process, reduce the dimensional fluctuation of the rotor outer circle caused by the change of punching force, and thus improve the stability of the entire processing process. By retaining the connection point between the rotor outer circle 2 and the residual material, that is, the position of the protrusion 4 or the groove 3, the breakage or deformation of the punching caused by stress concentration can be effectively reduced, thereby improving the yield rate and reducing the cost of scrap and reprocessing.

[0062] In one embodiment, the protrusion 4 or the groove 3 has two endpoints at both ends along the circumferential direction, and the angle formed by the line between the two endpoints and the center of the punch body 1 is γ, 1°≤γ≤70 / P°, where P is the number of rotor poles.

[0063] In one embodiment, the protrusion 4 or the groove 3 is located between the d-axis and the q-axis.

[0064] In order to optimize the motor cogging torque, the present invention conducts design research on the structure size and position of the protrusion 4 and the groove 3. Figures 13 to 15The following is a detailed description of the size and position of the protrusion or groove structure of the rotor punching of the embodiment of the present invention. According to the principle of motor science, under one pole, the center line of a single magnetic steel slot 6 is the d-axis of the rotor structure, and in two adjacent poles, the center line of the magnetic steel slot 6 is the q-axis of the rotor structure. The protrusion and groove structure of the embodiment of the present invention is located between the d-axis and the q-axis, and does not cross the d-axis and the q-axis, that is, the d-axis and the q-axis do not pass through the protrusion or groove. Between two adjacent d-axes, there is a protrusion 4 or a groove 3 or two protrusions 4 or grooves 3. If the number of rotor poles is P, the number of protrusions 4 or grooves 3 is P or 2P. If there are two protrusions 4 or grooves 3, they can be symmetrical about the d-axis or not. The maximum angle formed by the point on the outer contour of the protrusion 4 or groove 3 and the line connecting the center point of the rotor punching is γ. It has been found that γ has an effect on the motor cogging torque. The larger γ is, the greater the motor cogging torque is, and the worse the positioning accuracy of the robot using the motor is. γ cannot be too small. If γ is too small, the width of the protrusion 4 or the groove 3 along the circumferential direction will be too small, and it will not be able to play an effective connection and positioning effect during the rotor punching process. The qualitative relationship between γ and the motor cogging torque is as follows: Fig.17 As shown, the motor performance is optimal when 1°<γ≤70 / P°.

[0065] In one embodiment, the angle between the d-axis and the line connecting the end point of the protrusion 4 or the groove 3 close to the d-axis and the center of the punch body 1 is α, 20° / P≤α≤80° / P, where P is the number of rotor poles.

[0066] α is the minimum angle between the line connecting the point on the outer contour of the protrusion 4 or the groove 3 and the center point of the rotor punching and the d-axis. It has been found that α also affects the motor cogging torque. When 20 / P°≤α≤80 / P°, the motor cogging torque performance is optimal, and the robot positioning accuracy using this motor is the best. The qualitative relationship between α and the motor cogging torque is as follows: Fig.18 shown.

[0067] In one embodiment, the diameter of the rotor outer circle 2 is Ф. When a protrusion 4 is set on the rotor outer circle 2, the maximum diameter of the circle where the point on the outer contour of the protrusion 4 is located with the center of the punch body 1 as the center of the circle is ФC1, Ф<ФC1≤Ф+2 / 3*δ, where δ is the air gap width, Ф<ФC1≤Ф+2 / 3*δ, where δ is the air gap width.

[0068] When the connection structure on the outer circle of the rotor is a convex structure, ФC1 is a point on the outer contour of the convex structure as a point on the circle, and the center point of the rotor punching is the diameter of the largest circle formed by the center of the circle. When ФC1 is larger, the outer contour of the convex 4 deviates from the outer circle of the rotor 2. The change in the size of the air gap in the circumferential direction of the motor caused by this change is greater. According to the principle of motor science, the change in the circumferential distribution of the motor air gap directly causes the change in the motor cogging torque. The greater the deviation of the outer contour of the convex structure from the outer circle of the rotor, the worse the uniformity of the motor air gap, and the greater the motor cogging torque.

[0069] Further research found that when the connection structure is a convexity, when ФC1 and the outer contour of the rotor outer circle are taken as points on the circle, the outer contour of the rotor outer circle does not consider the convexity structure, and the diameter Ф of the largest circle formed by the rotor center and the air gap width δ satisfy the following relationship: Ф<ФC1≤Ф+2 / 3*δ. At this time, the motor tooth torque performance is optimal, and the robot positioning accuracy using this motor is the best, such as Fig.19 shown.

[0070] When the groove 3 is set on the outer circle 2 of the rotor, the minimum diameter of the circle where the point on the outer contour of the groove 3 is located with the center of the punch body 1 as the center is ФC2, Ф-2 / 3*δ≤ФC2<Ф, where δ is the air gap width.

[0071] When the connection structure on the outer circle of the rotor is a groove structure, ФC2 is a point on the outer contour of the polygonal groove structure as a point on the circle, and the center point of the rotor punching is the diameter of the smallest circle formed by the center of the circle. When ФC2 is smaller, the outer contour of the groove structure deviates from the outer circle of the rotor more, and the change in the size of the air gap in the circumferential direction of the motor caused by this change is greater. According to the principle of motor science, the change in the circumferential distribution of the motor air gap directly causes the change in the motor cogging torque. The greater the distance that the outer contour of the groove structure deviates from the outer circle of the rotor, the worse the uniformity of the motor air gap, and the greater the motor cogging torque.

[0072] Further research found that when the connection structure is groove 3, when ФC2 and the outer contour of the rotor outer circle 2 are taken as points on the circle, the outer contour of the rotor outer circle 2 does not consider the groove structure, and the diameter Ф of the largest circle formed by the rotor center and the air gap length δ satisfy the following relationship: Ф-2 / 3*δ≤ФC2<Ф, the motor tooth torque performance is optimal, and the robot positioning accuracy using this motor is the best, such as Fig. 20 shown.

[0073] In one embodiment, the outer contour of the rotor punching has 1 or 3n (n is an integer) arcs or straight lines. When the connection structure is a convex structure, the motor cogging torque performance is optimal when 0°<γ≤70 / P°, 20 / P°≤α≤80 / P° and Ф<ФC≤Ф+2 / 3*δ, and the robot positioning accuracy of the motor is the highest. When the connection structure is a groove structure, the motor cogging torque performance is optimal when 0°<γ≤70 / P°, 20 / P°≤α≤80 / P° and Ф-2 / 3*δ≤ФC<Ф, and the robot positioning accuracy of the motor is the highest.

[0074] By precisely controlling the position and shape of the connection structure, that is, the γ and α angles of the protrusions or grooves, and the relationship between the ФC diameter, the rotor outer contour diameter Ф, and the air gap length δ, the magnetic flux distribution in the motor air gap can be optimized. This optimization is crucial to improving the efficiency and power density of the motor, while also reducing the distortion of the magnetic flux waveform, which is conducive to forming a smooth sinusoidal waveform.

[0075] Cogging torque is the additional torque generated by the interaction between the stator and rotor teeth without external force. By limiting the γ and α angles within a specific range, the cogging torque can be effectively reduced, especially in the convex structure, when 0°<γ≤70 / P° and 20 / P°≤α≤80 / P°, and in the groove structure, when 0°<γ≤70 / P° and 20 / P°≤α≤80 / P°, the motor's cogging torque can be minimized, the motor will be smoother during operation, and unnecessary energy loss will be reduced.

[0076] The cogging torque and torque pulsation of the motor directly affect the positioning accuracy of the robot. When the rotor punching of this embodiment is adopted, due to the significant reduction of cogging torque and torque pulsation, the robot can achieve higher positioning accuracy and dynamic response performance when performing precision positioning tasks. By optimizing the relationship between the diameter of the circle where the protrusion or groove is located and Ф and δ, efficient utilization of materials can be achieved. Under the protrusion structure, the condition of Ф<ФC≤Ф+2 / 3δ ensures that the size of the protrusion structure is appropriate, neither too large to increase material waste nor too small to affect performance. Under the groove structure, the condition of Ф-2 / 3δ≤ФC<Ф also optimizes the size of the groove, thereby ensuring the performance of the motor while achieving reasonable cost control.

[0077] In one embodiment, the protrusion 4 or the groove 3 is formed by connecting a plurality of straight line segments in sequence to form a polygonal structure.

[0078] In one embodiment, the protrusion 4 or the groove 3 is formed by connecting a plurality of arc segments in sequence.

[0079] In one embodiment, the protrusion 4 or the groove 3 is formed by sequentially connecting a plurality of straight line segments and arc segments.

[0080] In one embodiment, the protrusion 4 or the groove 3 is an arc structure.

[0081] In one embodiment, the protrusion 4 or the groove 3 is a trapezoidal structure.

[0082] In one embodiment, the protrusion 4 or the groove 3 is a rectangular structure.

[0083] In one embodiment, the rotor outer circle 2 includes an arc or a straight line, or a combination of an arc and a straight line, and the end of the protrusion 4 or the groove 3 may not be directly connected to the arc segment of the rotor outer circle, but may be connected to the arc segment of the rotor outer circle through a straight line segment.

[0084] In one embodiment, when the number of protrusions 4 and / or grooves 3 is an even number, the protrusions 4 and / or grooves 3 are evenly distributed on both sides of the d-axis.

[0085] According to an embodiment of the present invention, a forming method of the above-mentioned rotor punching sheet includes:

[0086] Punching magnetic steel slot 6;

[0087] Punching the inner circle of the rotor 5;

[0088] Punching the rotor outer circle 2, wherein the rotor outer circle 2 is discontinuously separated from the residual material along the circumferential direction, and the rotor punching sheet is connected with the residual material at the protrusion 4 and / or the groove 3;

[0089] Punching is performed at the protrusion 4 or the groove 3 to disconnect the rotor punching sheet from the remaining material and form the rotor punching sheet.

[0090] The above-mentioned residual material refers to the remaining part of the blank after the rotor punching is completed.

[0091] In this embodiment, the outer contour of each pole of the rotor punching has 1 or 3n (n is an integer) arcs or straight lines, and also has a convex or concave structure. The rotor punching with a convex structure is as follows: Figure 7 and Figure 8 As shown, the rotor punching with groove structure is as follows Fig. 9 and Fig.10As shown. When the rotor punching is performed by the die, the punching process can be divided into two steps during the process of punching the outer contour. The first step is to punch out the outer contour arc of the rotor outer circle 2, and the second step is to punch out the protrusion or groove structure. When punching out the outer contour arc of the rotor outer circle 2, the rotor punching and the remaining material are still connected through the structure at the protrusion 4 or the groove 3. The method of punching out the outer contour in steps is adopted. When the rotor outer circle 2 is punched out in the first step, since some of the outer contour structures of the rotor punching have not been separated from the punching blank such as the electromagnetic steel sheet, the fixation is better. The dimensional accuracy of the outer contour arc and other parts of the rotor outer circle 2 punched out in the first step is much higher than the outer contour dimensional accuracy of the rotor outer circle of the traditional structure. In the second step, only the remaining connecting sections need to be punched out to complete the punching of the complete rotor punching. Since there are fewer remaining connecting sections and the stamping stress is smaller, the precision of the punched protrusion or groove structure is also much higher than the outer contour dimensional accuracy of the rotor with the traditional structure. The stamping process flow chart of the rotor punching of the embodiment of the present invention is shown as follows Fig.11 and 12 shown.

[0092] According to an embodiment of the present invention, the rotor core includes a plurality of rotor punchings stacked in the axial direction, and the rotor punchings are the above-mentioned rotor punchings.

[0093] According to an embodiment of the present invention, the servo motor includes a rotor core, and the rotor core is the above-mentioned rotor core.

[0094] According to an embodiment of the present invention, a robot includes the above-mentioned rotor core or the above-mentioned servo motor.

[0095] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0096] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0097] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A rotor punching, characterized in that: The invention comprises a punching sheet body (1), wherein the punching sheet body (1) has a rotor outer circle (2), and under one pole, a groove (3) which is recessed inwardly relative to the rotor outer circle (2) and / or a protrusion (4) which protrudes outwardly relative to the rotor outer circle (2) is provided on the rotor outer circle (2) of the punching sheet body (1).

2. The rotor punching according to claim 1, characterized in that: The protrusion (4) or the groove (3) has two endpoints at both ends along the circumferential direction, and the angle formed by the line connecting the two endpoints and the center of the punch body (1) is γ, 1°≤γ≤70 / P°, where P is the number of rotor poles.

3. The rotor punching according to claim 1, characterized in that: The angle between the d-axis and the line connecting the end point of the protrusion (4) or the groove (3) close to the d-axis and the center of the punch body (1) is α, 20° / P≤α≤80° / P, where P is the number of rotor poles.

4. The rotor punching according to claim 1, characterized in that: The diameter of the rotor outer circle (2) is Φ. When the protrusion (4) is provided on the rotor outer circle (2), the maximum diameter of the circle where the point on the outer contour of the protrusion (4) is located, with the center of the punch body (1) as the center of the circle, is ΦC1, Φ<ΦC1≤Φ+2 / 3*δ, where δ is the air gap width; when the groove (3) is provided on the rotor outer circle (2), the minimum diameter of the circle where the point on the outer contour of the groove (3) is located, with the center of the punch body (1) as the center of the circle, is ΦC2, Φ-2 / 3*δ≤ΦC2<Φ, where δ is the air gap width.

5. The rotor punching according to claim 1, characterized in that: The protrusion (4) or the groove (3) is located between the d-axis and the q-axis.

6. The rotor punching according to claim 1, characterized in that: The protrusion (4) or the groove (3) is formed by connecting a plurality of straight line segments in sequence; or, the protrusion (4) or the groove (3) is formed by connecting a plurality of arc line segments in sequence; or, the protrusion (4) or the groove (3) is formed by connecting a plurality of straight line segments and arc line segments in sequence.

7. The rotor punching according to claim 1, characterized in that: When the number of the protrusions (4) and / or the grooves (3) is an even number, the protrusions (4) and / or the grooves (3) are evenly distributed on both sides of the d-axis.

8. A method for forming a rotor punching sheet according to any one of claims 1 to 7, characterized in that: include: Punching magnetic steel slots (6); Punching the inner circle of the rotor (5); Punching a rotor outer circle (2), wherein the rotor outer circle (2) is separated from the residual material in a discontinuous manner along the circumferential direction, and the rotor punching sheet and the residual material are connected at the protrusion (4) and / or the groove (3); Punching is performed at the protrusion (4) or the groove (3) to disconnect the rotor punching sheet from the remaining material, thereby forming the rotor punching sheet.

9. A rotor core, comprising a plurality of rotor punchings stacked in an axial direction, characterized in that: The rotor punching is the rotor punching according to any one of claims 1 to 7.

10. A servo motor, comprising a rotor core, characterized in that: The rotor core is the rotor core according to claim 9.

11. A robot, characterized in that: It includes the rotor core according to claim 9 or the servo motor according to claim 10.

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