Machining method of permanent magnet synchronous motorized spindle motor for high-speed and high-precision numerical control machine tool

Abstract

The invention provides a processing method of a permanent magnet synchronous motorized spindle motor for a high-speed high-precision numerical control machine tool, which is used for optimally designing the processing technologies of a stator iron core, an armature winding, grinding of a stator iron core with a winding and a rotor iron core. A five-in-one lamination process is designed for the stator core, a dynamic paint dipping process is designed for the armature winding, a cooling-liquid-free intermittent air-cooling dry grinding process is designed for the stator core with the winding, and a seven-step lamination forming process is designed for the non-uniform segmented herringbone skewed pole rotor core. The electrical performance of the motorized spindle motor can be improved, and the overall precision of the motorized spindle can be improved.

Description

Technical Field

[0001] The present application relates to the field of permanent magnet synchronous electric spindle motors, and in particular to a method for machining permanent magnet synchronous electric spindle motors for high-speed and high-precision CNC machine tools. Background Art

[0002] Motor manufacturing involves the processing of multiple key components. Different materials require different processing techniques. The processing accuracy and process approach directly affect the overall performance and reliability of the motor. Spindle motors have been developing towards high power density and high speed. Precision machining and process design are the core key technologies in the motor manufacturing process. However, the current electric spindle motor manufacturing error is too large, which may cause rotor eccentricity and thus cause vibration of the electric spindle shaft system, resulting in unequal air gap lengths between the stator and the rotor, generating unilateral electromagnetic tension and causing electromagnetic oscillation, which ultimately affects the electrical and dynamic performance of the motor. As the core driving component of the electric spindle unit, the manufacturing accuracy and manufacturing process of the permanent magnet synchronous electric spindle motor directly affect the stability of the electric spindle operation and various key performance indicators. Therefore, it is urgent to design reasonable processing methods and process parameters so that the motor design performance can maximize its role. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a method for processing permanent magnet synchronous electric spindle motors for high-speed and high-precision CNC machine tools, which optimizes the process design from four aspects: stator core processing, armature winding processing, winding stator core processing, and rotor core processing. This helps to improve the electrical performance of the electric spindle motor and also helps to improve the overall accuracy of the electric spindle.

[0004] In order to achieve the above object, the present invention adopts the following technical scheme:

[0005] A method for processing a permanent magnet synchronous electric spindle motor for a high-speed and high-precision CNC machine tool, including stator core processing, armature winding processing, winding stator core grinding processing, and non-uniform segmented herringbone skewed pole rotor core processing;

[0006] A five-in-one lamination process is designed during the processing of the stator core, including: firstly, high-precision laser cutting of the stator electrical steel is performed in argon protection, then the clip slots are aligned and bonded piece by piece, the stator end plate plays an axial fixing role, clips are respectively inserted into the clip slots, the clip slots play a circumferential fixing role, the clips are bent after being laminated to the designed size by a press, and segmented staggered laser welding is performed under locking, pressure maintenance and argon protection, and finally high-temperature annealing is performed after welding to remove residual stress;

[0007] The dynamic varnishing process is designed in the process of armature winding processing, which is to optimize and transform the preheating, varnishing and drying processes in the process of armature winding processing, including preheating the armature winding as a whole and heating it locally, stirring it back and forth and performing vacuum varnishing, slow rotating baking and local ultraviolet curing;

[0008] During the grinding process of the winding stator core, a coolant-free intermittent air-cooled dry grinding process is designed, wherein the outer circle is coarsely ground to remove residual paint, the inner circle is finely ground to meet the air gap requirement, and the outer circle is finely ground to meet the interference requirement. During the grinding process of the winding stator core, no coolant is used, and compressed air is used to cool down and blow away iron chips.

[0009] During the processing of the non-uniform segmented herringbone skew-pole rotor core, a seven-step lamination forming process is designed. First, the rotor electrical steel is laser cut with high precision under argon protection, and then the multiple W-shaped welding grooves are aligned and bonded piece by piece. The press is pressed to the designed size, and each section of the rotor core is laser welded under the conditions of locking, pressure maintenance and argon protection. A non-magnetic plug-in plate is made, inserted into the magnetic steel slot for trial installation, and tested one by one to ensure that the magnetic steel can be inserted smoothly, and then the permanent magnet is coated with adhesive to install the magnetic steel. After the magnetic steel in each section of the rotor core is installed in order, the stainless steel rod is perforated and staggered for circumferential fixation, and the stainless steel end plate is axially fixed. The stainless steel rod and the stainless steel end plate are laser welded into one under the conditions of locking, pressure maintenance and argon protection. Finally, the inner and outer circles of the rotor core are ground to remove the multiple W-shaped welding grooves.

[0010] Furthermore, in the processing of the stator core, the outer circle of the stator electrical steel is provided with a first clip slot, a second clip slot, a third clip slot, a fourth clip slot, a fifth clip slot, and a sixth clip slot, which are evenly distributed on the circumference, and clips are respectively inserted into the clip slots for circumferential fixation of the stator core; in the five-in-one lamination process of the stator core, the number and position of the welding slots are optimized, and the number of welding slots is not an integer multiple of the number of motor poles; the center line of the welding slot is aligned with the center line of the stator tooth and cannot be located on the center line of the stator slot; the first stator end plate and the second stator end plate are located at the outermost side of the stator electrical steel to play an axial fixing role, and the friction in the circumferential direction is increased by adhesive between multiple pieces of stator electrical steel, and segmented staggered laser welding is performed under locking, pressure maintenance and argon protection, and the two sides of each clip are segmented.

[0011] Furthermore, in the processing of the non-uniform segmented herringbone skewed pole rotor core, the outer circle of the rotor core is symmetrically distributed with a first W-shaped welding groove, a second W-shaped welding groove, a third W-shaped welding groove, and a fourth W-shaped welding groove. Each W-shaped welding groove is arranged at the center line position between permanent magnets of the same polarity. After bonding, they are pressed to the designed size by a press and then locked. Then, each section of the rotor core is welded together.

[0012] Furthermore, the stainless steel rods and stainless steel end plates are made of 1Cr18Ni9Ti non-magnetic material for axial fixation of the rotor core, which has minimal impact on the magnetic field. The first stator end plate, the second stator end plate and the buckle are made of Q235-A material, which has good plasticity and weldability.

[0013] The present invention maximizes the performance of the motor design through a five-in-one lamination process for stator core design, a dynamic varnishing process for armature winding design, an intermittent air-cooled dry grinding process without coolant for stator core design with winding, and a seven-step lamination forming process for non-uniform segmented herringbone skewed-pole rotor core design.

[0014] Beneficial effects:

[0015] 1. The traditional stator core lamination process is carried out by selecting one of the three or two of the three: bonding, clip slot fixation, and welding. Different from the traditional method, the present invention designs a five-in-one stator core lamination process, which combines the five methods of bonding, axial fixation of the stator end plate, circumferential fixation of the clip slot, segmented staggered laser welding, and high-temperature annealing into one, and concentrates the advantages of the five methods. Adhesive can increase the friction between the stator electrical steel sheets in the circumferential direction, but relying solely on friction is not suitable for high-speed and high-power electric spindle motors; the clip slots can play an alignment and positioning role during stacking, which is sufficient when the stacking coefficient is not high, but for electric spindle motors with high power density and high stacking coefficient, only using clip slots to fix the stator core may cause the stator core to be a non-circular cylinder after stacking, resulting in a horseshoe phenomenon; electrical steel sheets are generally between 0.15mm and 0.5mm, and the thinner the stator core, the smaller the eddy current loss. The thinner the stator core, the easier it is for the outermost electrical steel sheet to partially bounce off after stacking, resulting in surface An arched protrusion appears. The present invention can solve this problem by adding a 5mm thick stator end plate for axial fixation. The biggest disadvantage of welding is that the melting of the local area will damage the insulating coating of the connection area, which will increase the eddy current loss and introduce residual stress, which will deteriorate the hysteresis characteristics of the material. The traditional arc welding is upgraded to segmented staggered laser welding. The laser welding heat input is more concentrated, the welding speed is faster, and the segmented staggered welding deformation is smaller, which has the least effect on the electromagnetic properties of the stator core. Few people pay attention to the residual stress after welding. The present invention adds a high-temperature annealing process after welding to remove the residual stress.

[0016] 2. In the present invention, argon protection is added during the high-precision laser cutting of stator and rotor electrical steel and the laser welding of stator core and rotor core. When the electrical steel is rapidly melted by the high-power laser beam, the alloy elements silicon and aluminum in the electrical steel are very likely to undergo high-temperature oxidation reaction with oxygen in the air to form a silicon-aluminum oxide layer. The argon protection can isolate oxygen and prevent the formation of high-temperature oxides.

[0017] 3. In the traditional stator core welding process, little attention is paid to the number and position of the welding slots, and most of the welding slots are designed based on experience. The present invention clearly emphasizes that from the perspective of reducing the imbalance of the three-phase electromotive force, the number of stator core welding slots should not be an integer multiple of the number of motor poles, and the center line of the welding slot must be aligned with the center line of the stator teeth, and it is strictly forbidden to be located on the center line of the stator slot. This process is conducive to improving the balance of the three-phase voltage and current of the high-speed, high-precision electric spindle motor.

[0018] 4. The traditional stator core varnishing process includes preheating, varnishing, and drying. Preheating is generally an overall preheating in an oven or a drying room. Varnishing is generally static varnishing in a vacuum. Drying is generally static drying in an oven or a drying room. The present invention designs a dynamic varnishing process. During the preheating process, overall preheating and local ultraviolet light heating are used to try to make the internal temperature of the winding higher; during the varnishing process, reciprocating stirring vacuum varnishing is used. The permeability of the insulating varnish into the stator winding can be increased by uninterrupted stirring of the paint solution. The stator winding paint film after varnishing is uniform, and the amount of paint can be more than doubled compared to static varnishing; during the drying process, slow rotation drying and local ultraviolet light curing are used. During static drying, the unsolidified insulating varnish will flow down. During the slow rotation drying process, the stator In the state of uniform rotation around the axis, the flow trajectory of the paint is circular, so the loss of the dipping paint is not only greatly reduced, but also with the rotation of the motor stator or rotor, it will continue to penetrate into the nearby gaps or defective parts, so that the quality of the dipping paint is improved; during the static drying process, the temperature outside the winding is high, the external insulating paint is cured first, and the internal insulating paint is cured later, which makes it easy for gaps to exist, and the external insulating paint is cured first, which also prevents the insulating paint from entering again during the second dipping. Local UV curing is used to heat the inside of the winding to speed up the curing progress inside the winding.

[0019] 5. The present invention adopts the scheme of first embedding wires, wiring, and varnishing before processing the inner and outer circles of the stator, so as to avoid first processing and then embedding wires, bumping and scratching the outer surface of the core during the winding production process, and to avoid first processing and then varnishing, so that the insulating paint in the winding flows out and adheres to the inner and outer circle surfaces of the stator core, affecting the surface quality.

[0020] 6. During the stator inner and outer circle machining process of the present invention, a coolant-free intermittent air-cooled dry grinding process is designed to prevent coolant from entering the winding, and compressed air is used to cool down and blow away iron chips.

[0021] 7. The non-uniform segmented herringbone skew-pole rotor core of the present invention adopts a seven-step lamination forming process to weld and fuse the stainless steel rods and stainless steel end plates together to ensure that there are no welding marks after processing. 1Cr18Ni9Ti stainless steel non-magnetic material is used for axial fixation of the rotor core, which has minimal impact on the magnetic field. The first stator end plate, the second stator end plate and the buckle are made of Q235-A material, which has good plasticity and weldability, is easier to bend into right angles to fasten and fix the stator electrical steel, and is also easier to weld with electrical steel. When the outer circle of the rotor core is processed, the grinding amount is greater than the designed W-shaped welding groove to ensure that the outer circle of the rotor core is smooth and the air gap between the stator core and the rotor core is uniform. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a flow chart of the method for machining a permanent magnet synchronous electric spindle motor for a high-speed and high-precision CNC machine tool of the present invention;

[0023] Figure 2 is a schematic diagram of the stator core;

[0024] Figure 3 is a schematic diagram of the rotor core;

[0025] Figure 4 It is a schematic diagram of the axial fixation of the non-uniform segmented herringbone skew-pole rotor core.

[0026] Among them, the figure markings are: first clip slot 1, second clip slot 2, third clip slot 3, fourth clip slot 4, fifth clip slot 5, sixth clip slot 6, stator tooth center line 7, stator slot center line 8, first stator end plate 9, second stator end plate 10, clip 11, stator electrical steel 12, segmented staggered laser welding 13, first W-shaped welding groove 14, second W-shaped welding groove 15, third W-shaped welding groove 16, fourth W-shaped welding groove 17, first stainless steel end plate 18, second stainless steel end plate 19, stainless steel rod 20, chamfered groove 21. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. Figure 1 As shown, a method for processing a permanent magnet synchronous electric spindle motor for a high-speed and high-precision CNC machine tool of the present invention includes stator core processing, armature winding processing, winding stator core grinding processing, and non-uniform segmented herringbone skewed pole rotor core processing.

[0028] A five-in-one lamination process is designed during the processing of the stator core, including: first, high-precision laser cutting of the stator electrical steel is performed in argon protection, then the clip slots are aligned and bonded piece by piece, the stator end plate plays an axial fixing role, clips are respectively inserted into the clip slots, the clip slots play a circumferential fixing role, the clips are bent after being laminated to the designed size by a press, and segmented staggered laser welding is performed under locking, pressure maintenance and argon protection, and finally high-temperature annealing is performed after welding to remove residual stress.

[0029] Specifically, Figure 2 As shown, six clip slots are arranged on the outer circle of the stator electrical steel 12, namely, the first clip slot 1, the second clip slot 2, the third clip slot 3, the fourth clip slot 4, the fifth clip slot 5, and the sixth clip slot 6 are evenly distributed on the circumference for fixing the stator core in the circumferential direction. In the five-in-one lamination process of the stator core, the number and position of the welding slots are optimized, from the perspective of reducing the imbalance of the three-phase electromotive force, that is, the number of the stator core welding slots should not be an integer multiple of the number of motor poles. Figure 2 In the welding groove, the welding groove is also a clip slot. The center line of the welding groove must be aligned with the center line of the stator tooth 7, and it is strictly forbidden to be located on the center line of the stator slot 8. The first stator end plate 9 and the second stator end plate 10 are located at the outermost side of the stator electrical steel 12, and play an axial fixing role. The first stator end plate, the second stator end plate and the clip are made of Q235-A material, which has good plasticity and weldability. It is easier to bend into a right angle to fasten and fix the stator electrical steel, and it is also easier to weld with the electrical steel. Adhesives are used to increase the friction in the circumferential direction between multiple pieces of stator electrical steel 12. Clips 11 are inserted into the first clip slot 1, the second clip slot 2, the third clip slot 3, the fourth clip slot 4, the fifth clip slot 5, and the sixth clip slot 6 respectively. The clip slots play a circumferential fixing role. Segmented staggered laser welding 13 is performed under locking, pressure maintenance, and argon protection. The two sides of each clip 11 are welded in sections. Figure 2 The three-section division is for illustration only; the specific number of sections and the length of each section can be determined according to the axial length of the stator core, but adjacent sections must be staggered.

[0030] The armature winding processing includes armature winding coil production, followed by wire embedding, wiring, preheating, varnishing, and finally drying. The present invention optimizes and transforms the preheating, varnishing, and drying processes, that is, a dynamic varnishing process is designed, including preheating the armature winding as a whole and locally heating it, reciprocating stirring and vacuum varnishing, slow rotation baking, and local ultraviolet light curing.

[0031] In the process of grinding the stator core with winding, a coolant-free intermittent air-cooled dry grinding process is designed. First, the stator core shaft is ground, and then the stator core shaft is inserted into the inner circle of the stator. The coolant-free intermittent air-cooled dry grinding process is designed, that is, the outer circle is coarsely ground to remove residual paint, the inner circle is finely ground to meet the air gap requirement, and the outer circle is finely ground to meet the interference requirement. In the whole process of grinding the stator core with winding, no coolant is used to prevent the coolant from entering the winding, and compressed air is used to cool down and blow away the iron filings.

[0032] During the processing of the non-uniform segmented herringbone skew-pole rotor core, a seven-step lamination forming process is designed. First, the rotor electrical steel is laser cut with high precision under argon protection, and then multiple W-shaped welding grooves are aligned and bonded piece by piece. The press is pressed to the designed size, and each section of the rotor core is laser welded under the conditions of locking, pressure maintenance and argon protection. A non-magnetic plug-in plate is made, inserted into the magnetic steel slot for trial installation, and tested one by one to ensure that the magnetic steel can be inserted smoothly, and then the permanent magnet is coated with adhesive to install the magnetic steel. After the magnetic steel in each section of the rotor core is installed in order, the stainless steel rod is perforated and staggered for circumferential fixation, and the stainless steel end plate is axially fixed. The stainless steel rod and the stainless steel end plate are laser welded into one under the conditions of locking, pressure maintenance and argon protection. Finally, the inner and outer circumferential grinding of the rotor core is performed to remove multiple W-shaped welding grooves.

[0033] like Figure 3 As shown, four W-shaped welding grooves are symmetrically distributed on the outer circle of the rotor core, namely, a first W-shaped welding groove 14, a second W-shaped welding groove 15, a third W-shaped welding groove 16, and a fourth W-shaped welding groove 17. The W-shaped welding grooves have the least influence on the electromagnetic properties of the rotor core at the center line position between permanent magnets N and N, or S and S of the same polarity. After bonding, they are stacked to the designed size by a press and locked, and then each section of the rotor core is welded together. Figure 3 middle, The reference diameter size to be processed by the outer circle grinding of the rotor core. The grinding amount must be greater than the designed W-shaped welding groove to ensure that the final outer circle diameter of the rotor core is less than , ensuring uniform air gap between stator core and rotor core.

[0034] like Figure 4 As shown, L1, L2, L3, L4, L5, and L6 are the axial lengths of each section of the rotor core, respectively, and the lengths L1=L6>L2=L5>L3=L4. Unequal lengths indicate non-uniform segmentation. After each section of the rotor core is welded together, the stainless steel rod 20 is welded together with the first stainless steel end plate 18, the second stainless steel end plate 19, and the chamfered groove 21 on the stainless steel rod 20 by laser welding, and the outer surfaces are polished.

[0035] Preferably, to ensure that there are no welding marks on the surface after processing, the stainless steel rod 20 and the first stainless steel end plate 18 and the second stainless steel end plate 19 are made of 1Cr18Ni9Ti non-magnetic material for axial fixation of the rotor core, which minimizes the impact on the magnetic field.

Claims

1. A method for machining a permanent magnet synchronous electric spindle motor for a high-speed and high-precision CNC machine tool, characterized in that: Including stator core processing, armature winding processing, winding stator core grinding processing, non-uniform segmented herringbone skewed pole rotor core processing; The stator core processing process adopts a five-in-one lamination process, including: firstly, high-precision laser cutting of stator electrical steel is performed in argon protection, then the clip slots are aligned and bonded piece by piece, the stator end plate plays an axial fixing role, the clips are inserted into the clip slots, the clip slots play a circumferential fixing role, the clips are bent after press lamination, and segmented staggered laser welding is performed under locking and pressure maintenance and argon protection, and finally high-temperature annealing is performed after welding to remove residual stress; The armature winding processing includes designing a dynamic varnishing process, including preheating the armature winding as a whole and locally heating it, reciprocating stirring and vacuum varnishing, slow rotation baking and local UV curing; During the grinding process of the winding stator core, a coolant-free intermittent air-cooled dry grinding process is designed, wherein the outer circle is coarsely ground to remove residual paint, the inner circle is finely ground to meet the air gap requirement, and the outer circle is finely ground to meet the interference requirement. During the grinding process of the winding stator core, no coolant is used throughout the process. During the processing of the non-uniform segmented herringbone skew-pole rotor core, a seven-step lamination forming process is designed. First, the rotor electrical steel is laser cut with high precision under argon protection, and then multiple W-shaped welding grooves are aligned and bonded piece by piece. Each section of the rotor core is laminated and locked for pressure maintenance using a press, and laser welded under argon protection. A non-magnetic plug-in plate is made, inserted into the magnetic steel slot for trial installation, and tested one by one to ensure that the magnetic steel can be inserted smoothly, and then the permanent magnet is coated with adhesive to install the magnetic steel. After the magnetic steel in each section of the rotor core is installed in order, the stainless steel rod is perforated and installed circumferentially with staggered poles, and the stainless steel end plate is fixed axially. The stainless steel rod and the stainless steel end plate are laser welded into one under locking, pressure maintenance and argon protection. Finally, the inner and outer circumferential grinding of the rotor core is performed to remove multiple W-shaped welding grooves.

2. The method for machining a permanent magnet synchronous electric spindle motor for a high-speed and high-precision CNC machine tool according to claim 1, characterized in that: The armature winding processing includes armature winding coil production, followed by wire embedding, wiring, preheating, varnish dipping, and finally drying. The intermittent air-cooled dry grinding process without coolant is to optimize the preheating, varnish dipping, and drying processes.

3. The method for machining a permanent magnet synchronous electric spindle motor for a high-speed and high-precision CNC machine tool according to claim 1, characterized in that: The process of grinding the winding stator core, before the intermittent air-cooled dry grinding process without coolant, also includes: first grinding the stator core shaft, and then inserting the stator core shaft into the inner circle of the stator.

4. The method for machining a permanent magnet synchronous electric spindle motor for a high-speed and high-precision CNC machine tool according to claim 1, characterized in that: In the processing of the stator core, the outer circle of the stator electrical steel is provided with a first clip slot, a second clip slot, a third clip slot, a fourth clip slot, a fifth clip slot, and a sixth clip slot, which are evenly distributed on the circumference and are used for circumferential fixation of the stator core; in the five-in-one lamination process of the stator core, the number and position of the welding slots are optimized, and the number of the welding slots is not an integer multiple of the number of motor poles; the center line of the welding slot is aligned with the center line of the stator tooth and cannot be located on the center line of the stator slot; the first stator end plate and the second stator end plate are located at the outermost side of the stator electrical steel, and play an axial fixing role; the friction force in the circumferential direction is increased between multiple pieces of stator electrical steel by adhesive; clips are respectively inserted into the first clip slot, the second clip slot, the third clip slot, the fourth clip slot, the fifth clip slot, and the sixth clip slot, and the clip slots play a circumferential fixing role; segmented staggered laser welding is performed under locking and pressure maintenance and argon protection, and each clip is welded in segments.

5. The method for machining a permanent magnet synchronous electric spindle motor for a high-speed and high-precision CNC machine tool according to claim 1, characterized in that: In the processing of the non-uniform segmented herringbone skewed-pole rotor core, the first W-shaped welding groove, the second W-shaped welding groove, the third W-shaped welding groove, and the fourth W-shaped welding groove are symmetrically distributed on the outer circle of the rotor core. Each W-shaped welding groove is set at the center line position between the permanent magnets of the same polarity. After bonding, it is pressed to the designed size by a press and then locked. Then, each section of the rotor core is welded together.

6. A method for machining a permanent magnet synchronous electric spindle motor for a high-speed and high-precision CNC machine tool according to claim 4, characterized in that: The stainless steel rods and stainless steel end plates are made of 1Cr18Ni9Ti non-magnetic material and are used for axial fixation of the rotor core. The first stator end plate, the second stator end plate and the buckle are made of Q235-A material.

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