Novel permanent magnet synchronous double-shaft type grinding electric spindle

Abstract

The utility model discloses a novel permanent magnet synchronous double-shaft type grinding motorized spindle, which relates to the technical field of machining and comprises a driving shaft and a driven shaft, the driving shaft is provided with a rear machine body, a stator assembly, a rotor assembly, an upper bearing assembly, an aluminum water jacket and a lower bearing gland, and the driven shaft is integrally arranged at the lower end of the driving shaft. The driven shaft comprises a front machine body, a coupler, a driven bearing assembly, a dustproof cover, a dustproof cap assembly and a grinding wheel assembly. According to the double-shaft type grinding electric spindle, the rigidity is improved by optimizing the bearing span, the double shafts are connected through the plum blossom type elastic coupler buffer pad, the deep hole grinding integrated forming technology is achieved, deep holes within 300 mm can be machined at a time, meanwhile, the efficiency and the power density are improved through the permanent magnet synchronous motor, the spindle is designed to be provided with a cooling liquid channel, and a cutter is cooled in real time; machining precision is improved, space and cost are saved, and the performance and the service life of the motorized spindle are comprehensively improved.

Description

Technical Field

[0001] The utility model relates to the technical field of mechanical processing, in particular to a novel permanent magnet synchronous double-axis grinding electric spindle. Background Art

[0002] With the development and application of new technologies, grinding efficiency, precision, and processing range have significantly improved in recent years. Grinding plays a particularly crucial role in the efficient and high-precision machining of difficult-to-machine materials, with a growing number of new grinding technologies, processes, and finished products. The electric grinding spindle is the core functional component of high-precision grinding equipment. The dynamic and static performance of the spindle shaft system directly determines the technical performance indicators of high-precision grinding equipment and is crucial to the ultimate precision of manufacturing.

[0003] In the prior art, traditional grinding spindles often adopt an external motor, driven by a high-frequency motor, and use a transmission mechanism to transmit the motor power to the spindle to achieve grinding. The introduction of the transmission mechanism in the precision grinding system will lead to a decrease in the efficiency of the entire machine, an extension of the system response time and a decrease in the processing accuracy of the entire machine; at the same time, this method has relatively poor system integration, a relatively large volume, and introduces a large number of fitting errors in the manufacturing process, which is not conducive to the precision of high-precision grinding equipment; in addition, in the prior art, high-precision deep hole grinding, due to the long length of the deep hole spindle, when performing internal cylindrical grinding, the grinding wheel vibrates greatly, and the heat at the shaft end is transmitted to the grinding wheel, causing the bearing at the grinding wheel to be extremely easy to damage, and it cannot meet long-term stable production; at the same time, during the rotation of the spindle, the bearing needs to bear the radial load of the external body. Since the body is a circular ring structure, the radial stiffness of the spindle will drop sharply, resulting in tool deflection and vibration during deep hole grinding, thereby reducing the grinding accuracy and failing to meet high-precision processing requirements. Utility Model Content

[0004] In view of the deficiencies in the prior art, the present invention provides a novel permanent magnet synchronous dual-axis grinding electric spindle, which solves the problems raised by the above-mentioned background technology.

[0005] To achieve the above objectives, the utility model is implemented through the following technical solutions: a new type of permanent magnet synchronous dual-axis grinding electric spindle, including a driving shaft and a driven shaft, the driving shaft is provided with a rear body, a stator assembly, a rotor assembly, an upper bearing assembly, an aluminum water jacket and a lower bearing pressure cover, the driven shaft is arranged as a whole at the lower end of the driving shaft, and the driven shaft includes a front body, a coupling, a driven bearing assembly, a dust cover, a dust cap assembly and a grinding wheel assembly.

[0006] Furthermore, a bearing chamber is provided at the lower portion of the rear body of the driving shaft, an angular contact ball bearing in a DT combination is provided in the bearing chamber, and a lower bearing pressure cover for fixing the bearing is provided at the lower portion of the angular contact ball bearing.

[0007] Furthermore, a receiving cavity is recessed in the middle of the rear body, the stator assembly is slidably fitted in the receiving cavity and fixed by machine screws; an upper bearing assembly is connected and fixed to the upper opening of the rear body, and an aluminum water jacket is fixed to the upper part of the upper bearing assembly.

[0008] Furthermore, a rotor assembly is provided below the aluminum water jacket, and the rotor assembly passes through the middle through holes of the aluminum water jacket, the upper bearing assembly, the stator assembly, and the lower bearing gland.

[0009] Furthermore, the front body is a variable-section cylindrical structure and is T-shaped. The front body flange shaft is provided with a plurality of liquid inlets, which are interconnected with the radial liquid inlet hole and the axial liquid hole of the front body, and are connected to the first water spray hole at the bottom of the dust cap.

[0010] Furthermore, the rear body is provided with a cooling mechanism, which consists of a water inlet, a water outlet and a cooling channel. The cooling channel includes a plurality of water channel holes and waist-shaped water channel grooves. The water channel holes and waist-shaped water channel grooves exist independently and are distributed in a ring shape.

[0011] Furthermore, the rotor assembly includes a shaft core and a rotor iron core. The shaft core shaft body wall is provided with bearing locking threads on the upper and lower parts, and a rotating shaft section is provided in the middle. The rotor iron core is installed on the rotating shaft section. The outer wall of the rotor iron core is provided with a plurality of arc grooves, and the arc grooves are equipped with permanent magnets.

[0012] Furthermore, a bearing locking front nut and a bearing locking rear nut are provided on the upper and lower outer walls of the coupling shaft, a plum blossom groove structure is provided on the upper part of the coupling, and a plum blossom-shaped elastic buffer pad is provided in the plum blossom groove structure of the coupling.

[0013] Furthermore, the dust cap assembly and the dust cover together form a dustproof mechanism, the dust cap assembly includes a dust cap and an insert, the dust cap is provided with a concave mounting cavity that just accommodates the insert, the insert is interference fit in the concave mounting cavity, and the lower part of the dust cap is provided with a plurality of evenly distributed second water spray holes.

[0014] Furthermore, the grinding wheel assembly is arranged at the lower part of the coupling, including a grinding wheel frame, a grinding wheel, a pressure plate and a fixing nut. The grinding wheel is locked on the coupling through the fixing nut and rotates synchronously with the coupling.

[0015] The utility model provides a new type of permanent magnet synchronous dual-axis grinding electric spindle. Compared with the existing technology, it has the following advantages:

[0016] 1. The front overhang significantly affects the overall stiffness of the spindle assembly, so the spindle structure should be minimized as much as possible. However, the span's impact on overall stiffness is not a one-way street; a span that is too large or too small will reduce spindle stiffness. Therefore, an optimal span that satisfies the minimum fine deflection requirement at the spindle front end is required. This utility model utilizes finite element analysis software (such as Ansys) to analyze the structural material properties and combines numerical analytical methods such as the transfer matrix method to calculate the frequencies and vibration modes of each order of the electric spindle. Using the first-order natural frequency and vibration mode from the spindle's modal inherent characteristics analysis as the objective function, the spindle bearing span is optimized. This dual-shaft design achieves a longer bearing span and greater stiffness.

[0017] 2. The double shafts are connected by a plum blossom-shaped elastic coupling buffer pad. The plum blossom-shaped elastic coupling buffer pad is made of polyurethane. When this plum blossom-shaped elastic coupling buffer pad is installed in the coupling, it can play the role of connecting transmission, transmitting power between the two couplings, and has a certain rebound effect. When force acts on its petals, it can play a certain role in slowing down the rebound, so it also plays a buffering role. It can compensate for the relative offset of the two shafts and has the characteristics of no lubrication and easy maintenance. At the same time, the elastomer buffer pad made of polyurethane material also has a long service life, thereby increasing the service life of the main shaft system.

[0018] 3. It possesses integrated deep-hole grinding technology. Conventional built-in grinding electric spindles typically have a grinding depth of less than 100mm and require multiple machining operations. However, with the continuous advancement of modern machining technology, conventional grinding depths no longer meet machining requirements. Deep-hole grinding exceeding 100mm, 200mm, and 300mm has become a major challenge. Conventional electric spindles are unable to meet these machining requirements. The grinding depth of conventional electric spindles is primarily determined by the size of the spindle shaft end and the size of the grinding adapter. The dual-axis grinding electric spindle provided in this project features integrated deep-hole grinding technology. By adding a grinding spindle extension structure, the machining depth of the grinding electric spindle can be extended, enabling the grinding electric spindle to machine deep holes of less than 300mm in a single operation, eliminating the need for repeated clamping and saving machining time and costs.

[0019] 4. Use permanent magnet synchronous motor: Using permanent magnets to provide excitation makes the motor structure simpler, reduces processing and assembly costs, and eliminates slip rings and brushes that are prone to problems, thereby improving the reliability of motor operation; and because no excitation current is required, there is no excitation loss, which improves the efficiency and power density of the motor.

[0020] 5. The coolant for the spindle during operation is provided by the coolant channel of the spindle itself, and the coolant is transported from the rear end of the spindle to the center of the grinding head, rather than requiring additional external cooling equipment. This design can not only cool the tool in real time when the spindle is working, improve machining accuracy, and extend the service life of the grinding head; at the same time, it can also reduce the installation space, save machining costs, and improve economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a cross-sectional view of the overall internal structure of the utility model.

[0022] Figure 2 This is a schematic diagram of the axonometric view of the rear body of the utility model.

[0023] Figure 3 This is a schematic axonometric diagram of the front body of the utility model.

[0024] Figure 4 This is an axonometric diagram of the rotor structure of the utility model.

[0025] Figure 5 This is an axonometric diagram of the dust cap assembly of the present invention.

[0026] Figure 6 This is a cross-sectional view of the internal structure of the dust cap assembly of the present invention.

[0027] In the figure: 1. driving shaft; 2. driven shaft; 3. rear body; 4. stator assembly; 5. rotor assembly; 6. upper bearing assembly; 7. aluminum water jacket; 8. lower bearing gland; 9. angular contact ball bearing; 10. machine screw; 11. front body; 12. coupling; 13. driven bearing assembly; 14. dust cover; 15. dust cap assembly; 16. grinding wheel assembly; 17. radial liquid inlet hole; 18. axial liquid hole; 19. first water spray hole; 20. water inlet; 21. water outlet; 22. cooling channel; 23. water channel hole; 24. waist-shaped water channel groove; 25. water channel gasket; 26. core base; 27. Edge plate; 28. Coil winding; 29. ​​Shaft core; 30. Rotor core; 31. Shaft core front nut; 32. Shaft core rear nut; 33. Plum blossom groove structure; 34. Bearing locking front nut; 35. Bearing locking rear nut; 36. Plum blossom elastic buffer pad; 37. Cylindrical petal; 38. Bearing seat; 39. Base plate; 40. Upper bearing spacer; 41. Dustproof mechanism; 42. Dustproof cap; 43. Insert; 44. Concave mounting cavity; 45. Diverter groove; 46. Axial air inlet hole; 47. Radial air hole; 48. Second water spray hole; 49. Grinding wheel frame; 50. Grinding wheel; 51. Pressure plate; 52. Fixing nut. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0029] See also Figure 1-4 The utility model provides a technical solution: a new type of permanent magnet synchronous dual-axis grinding electric spindle, including a driving shaft 1 and a driven shaft 2. The driving shaft 1 includes a rear body 3, a stator assembly 4, a rotor assembly 5, an upper bearing assembly 6, an aluminum water jacket 7, and a lower bearing pressure cover 8. A bearing chamber is provided at the lower part of the rear body 3, in which an angular contact ball bearing 9 in a DT combination is provided. A lower bearing pressure cover 8 for fixing the bearing is provided at the lower part of the angular contact ball bearing 9. A receiving cavity is recessed in the middle part of the rear body 3, in which the stator assembly 4 is slidably fitted and fixed by a machine screw 10. The upper bearing assembly 6 is connected and fixed to the upper opening of the rear body 3, and the upper part of the upper bearing assembly 6 is fixed to the aluminum water jacket 7. A rotor assembly 5 is provided below the aluminum water jacket 7, and the rotor assembly 5 passes through the middle through-holes of the aluminum water jacket 7, the upper bearing assembly 6, the stator assembly 4, and the lower bearing pressure cover 8.

[0030] The driven shaft 2 is integrally mounted at the lower end of the driving shaft 1. The driven shaft 2 comprises a front body 11, a coupling 12, a driven bearing assembly 13, a dust cover 14, a dust cap assembly 15, and a grinding wheel assembly 16. The flange end of the front body 11 is fixedly connected to the rear body 3 via screws. The driven bearing assembly 13 is mounted on both the lower and upper annular surfaces of the front body 11. The dust cover 14, the dust cap assembly 15, and the grinding wheel assembly 16 are sequentially mounted at the lower end of the front body 11. The coupling 12 is inserted through the central through-holes of the front body 11, the driven bearing assembly 13, the dust cover 14, and the dust cap assembly 15.

[0031] The front body 11 is a variable cross-section cylindrical structure in the shape of a T. The flange shaft of the front body 11 is provided with a plurality of liquid inlets, which are connected to the radial liquid inlet holes 17 and the axial liquid hole 18 of the front body 11, and are connected to the first water spray hole 19 at the bottom of the dust cap.

[0032] The rear body 3 is equipped with a cooling mechanism consisting of a water inlet 20, a water outlet 21, and a cooling channel 22. The cooling channel 22 includes a plurality of water holes 23 and a waist-shaped water channel groove 24. The water holes 23 and the waist-shaped water channel groove 24 are independent and arranged in a ring. The cooling water holes 23 are interconnected through the waist-shaped water channel groove 24 to form a circulating cooling system. The circulating water channel at both ends of the rear body 3 is sealed by water channel gaskets 25 in the waist-shaped water channel groove 24. The cross-sectional shape of the water channel gasket 25 is consistent with that of the waist-shaped water channel groove 24. The water channel gasket 25 is evenly applied with AB glue to ensure that the coolant does not overflow when the spindle is operating.

[0033] The stator assembly 4 is positioned using positioning holes in the rear housing 3's outer shaft and external screws 10, limiting its axial and radial range of motion. The stator assembly 4 consists of a cylindrical core 26, insulating plates 27 positioned at each end of the core 26, and coil windings 28 connected to the insulating plates. The core 26 is constructed from a laminated stack of silicon steel sheets of equal thickness. Its interior is equipped with an annular array of slot wedges. The windings are wound with enameled wire of equal diameter and embedded within the slot wedges. A PTC-130 thermistor is also embedded within the stator windings to monitor temperature.

[0034] The rotor assembly 5 comprises a shaft core 29 and a rotor core 30. The shaft core 29 has bearing locking threads on its upper and lower outer walls. These threads are fitted with a front nut 31 and a rear nut 32, which threadably secure the angular contact ball bearing 9. A central shaft section is provided, onto which the rotor core 30 is mounted. The rotor assembly 5 is magnetized by permanent magnets. The outer wall of the rotor core 30 is provided with several arc-shaped grooves, separated by ribs. Permanent magnets are mounted in these grooves. The inner and outer walls of the permanent magnets are arc-shaped, with thickness gradually decreasing from the center to the sides. An outer protective sleeve is interference-fitted onto the outer arc of the permanent magnets, which are also coated with an insulating coating. The inner arc of the permanent magnets has the same shape as the arc grooves of the rotor core. Each arc groove of the rotor core 30 contains one or more permanent magnets. A hexagonal groove structure 33 is provided at the lower portion of the shaft core 29.

[0035] The outer wall of the coupling 12 is provided with a front bearing locking nut 34 and a rear bearing locking nut 35, which can be used to tighten the bearing. The upper portion of the coupling 12 is provided with a plum blossom groove structure 33, and the plum blossom-shaped elastic buffer 36 is provided within the plum blossom groove structure 33 of the coupling. The plum blossom-shaped elastic buffer 36 comprises a cylindrical body and cylindrical petals 37 arranged annularly along the cylindrical body. The cylindrical petals 37 and the cylindrical body are formed as one piece by casting. The plum blossom-shaped elastic buffer 36 is made of polyurethane. The coupling 12 is fitted with the shaft core 29 through the plum blossom groove structure 33 and rotates synchronously with the shaft core 29.

[0036] Upper bearing assembly 6 comprises a bearing seat 38, a base plate 39, an upper bearing spacer 40, and several angular contact ball bearings 9 stacked within the bearing seat. Bearing seat 38 and base plate 39 are secured together with screws. This modular structure facilitates machining and assembly and disassembly, and allows for better adjustment of the spindle's axial stability.

[0037] A step is provided at the bottom of the aluminum water jacket 7, which can be just embedded in the upper part of the inner cavity of the bearing seat 38. The upper end face of the aluminum water jacket 7 is provided with a cooling interface and a power main line interface for cooling. The aluminum water jacket 7 is an aluminum structure and has undergone a hard anodizing process, which has good anti-oxidation and anti-corrosion effects.

[0038] The dustproof mechanism 41 comprises a dust cap assembly 15 and a dust cover 14. The lower portion of the dust cover 14 features a labyrinthine structure that mates with the bearing locking front nut 34. The dust cap assembly 15 comprises a dust cap 42 and an insert 43. The dust cap 42 is provided with a concave mounting cavity 44 that precisely accommodates the insert. The insert 43 is interference-fitted within the concave mounting cavity 44 and assembled together via laser welding. The insert 43 has an annular confluence groove on one side of the concave mounting cavity 44 and multiple diverter grooves 45 radially and evenly distributed along its inner wall. These diverter grooves 45 extend into and communicate with the annular confluence groove. The diverter grooves 45 communicate with the axial air inlet 46 and radial air holes 47 of the dust cap. The lower portion of the dust cap 42 is provided with several evenly distributed second water spray holes 48. These second water spray holes 48 spray coolant in a parabolic pattern, effectively cooling the machining tool.

[0039] The grinding wheel assembly 16 is arranged at the lower part of the coupling 12. The grinding wheel assembly 16 includes a grinding wheel frame 49, a grinding wheel 50, a pressure plate 51 and a fixing nut 52. The grinding wheel 50 is locked on the coupling 12 through the fixing nut 52 and rotates synchronously with the coupling 12.

[0040] The operating principle of this utility model is as follows: When three-phase AC current flows through the stator assembly 4 of a permanent magnet synchronous motor, the rotating armature magnetomotive force (MMF) and the resulting armature magnetic field generated by the three-phase AC current, on the one hand, cut through the stator coil winding 28, generating an induced electromotive force in the stator coil winding 28; on the other hand, the electromagnetic force draws the rotor assembly 5 to rotate at the synchronous speed. The armature current also generates stator winding leakage flux that intersects only with the stator coil winding 28, generating an induced leakage electromotive force in the stator coil winding 28. Furthermore, the magnetic field generated by the rotor permanent magnets also cuts through the stator winding at the synchronous speed, thereby generating a no-load electromotive force.

[0041] When the utility model is working, the front dust-proof air curtain air source is opened, and the compressed air that meets the requirements is connected from the air inlet of the aluminum water jacket 7, enters the dust cap 42 and maintains positive pressure, preventing sewage, cutting chips, etc. outside the body from entering the main shaft 1, which greatly reduces the failure rate of the main shaft 1 during operation.

[0042] When the utility model is working, the coolant is introduced from the water inlet of the aluminum water jacket 7, enters the rear body 3 through the upper bearing assembly 6, and returns to the upper bearing assembly 6 after circulating around the rear body 3, and then flows out from the water outlet of the aluminum water jacket 7, taking away the heat generated by the friction when the motor is working and the bearings are running at high speed, thereby improving the processing accuracy and extending the service life of the main shaft 1.

[0043] When the utility model is working, several coolant inlets on the flange of the front body 11 are opened, and the coolant flows to the first water spray hole at the lower part of the dust cap 42 through the axial liquid inlet hole and the radial liquid hole of the front body 11, and sprays out the coolant in a parabolic shape, cooling the processing tool in real time, having a good cooling effect, improving the processing accuracy, and extending the service life of the grinding head.

[0044] The above description is only a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Technical personnel in this industry can make some deformation and modifications under the inspiration of this technical solution. Any modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A new type of permanent magnet synchronous dual-axis grinding electric spindle, characterized in that: The invention comprises a driving shaft (1) and a driven shaft (2), wherein the driving shaft (1) is provided with a rear body (3), a stator assembly (4), a rotor assembly (5), an upper bearing assembly (6), an aluminum water jacket (7) and a lower bearing pressure cover (8), and the driven shaft (2) is integrally arranged at the lower end of the driving shaft (1), and the driven shaft (2) comprises a front body (11), a coupling (12), a driven bearing assembly (13), a dust cover (14), a dust cap assembly (15) and a grinding wheel assembly (16); The middle part of the rear body (3) is provided with an accommodating cavity, the stator assembly (4) is slidably fitted in the accommodating cavity and fixed by a screw (10); an upper bearing assembly (6) is connected and fixed to the upper opening of the rear body (3), and an aluminum water jacket (7) is fixed to the upper part of the upper bearing assembly (6); A rotor assembly (5) is provided below the aluminum water jacket (7), and the rotor assembly (5) passes through the middle through holes of the aluminum water jacket (7), the upper bearing assembly (6), the stator assembly (4), and the lower bearing gland (8); The front body (11) is a variable cross-section cylindrical structure and is T-shaped. The flange shaft of the front body (11) is provided with a plurality of liquid inlets. The liquid inlets are connected to the radial liquid inlet hole (17) and the axial liquid hole (18) of the front body (11), and are connected to the first water spray hole (19) at the lower part of the dust cap (42).

2. A novel permanent magnet synchronous dual-axis grinding electric spindle according to claim 1, characterized in that: A bearing chamber is provided at the lower portion of the rear body (3) of the driving shaft (1), an angular contact ball bearing (9) in a DT combination is provided in the bearing chamber, and a lower bearing pressure cover (8) for fixing the bearing is provided at the lower portion of the angular contact ball bearing (9).

3. The novel permanent magnet synchronous dual-axis grinding electric spindle according to claim 1 is characterized in that: The rear body (3) is provided with a cooling mechanism, which is composed of a water inlet (20), a water outlet (21) and a cooling channel (22). The cooling channel (22) includes a plurality of water channel holes (23) and waist-shaped water channel grooves (24). The water channel holes (23) and waist-shaped water channel grooves (24) exist independently and are distributed in a ring shape.

4. A novel permanent magnet synchronous dual-axis grinding electric spindle according to claim 3, characterized in that: The rotor assembly (5) comprises a shaft core (29) and a rotor core (30). The shaft core (29) is provided with bearing locking threads on the upper and lower outer walls thereof, and a rotating shaft section is provided in the middle thereof. The rotor core (30) is mounted on the rotating shaft section. The outer wall of the rotor core (30) is provided with a plurality of circular arc grooves, and permanent magnets are mounted on the circular arc grooves.

5. The novel permanent magnet synchronous dual-axis grinding electric spindle according to claim 1 is characterized in that: A bearing locking front nut (34) and a bearing locking rear nut (35) are provided on the upper and lower outer walls of the shaft of the coupling (12), a plum blossom groove structure (33) is provided on the upper portion of the coupling (12), and a plum blossom-shaped elastic buffer pad (36) is provided in the plum blossom groove structure (33) of the coupling.

6. The novel permanent magnet synchronous dual-axis grinding electric spindle according to claim 1 is characterized in that: The dust cap assembly (15) and the dust cover (14) together form a dustproof mechanism (41). The dust cap assembly (15) includes a dust cap (42) and an insert (43). The dust cap (42) is provided with a concave mounting cavity (44) that just accommodates the insert (43). The insert (43) is interference-fitted in the concave mounting cavity (44). A plurality of evenly distributed second water spray holes (48) are provided at the lower portion of the dust cap (42).

7. The novel permanent magnet synchronous dual-axis grinding electric spindle according to claim 1 is characterized in that: The grinding wheel assembly (16) is arranged at the lower part of the coupling (12), and includes a grinding wheel frame (49), a grinding wheel (50), a pressure plate (51) and a fixing nut (52). The grinding wheel (50) is locked on the coupling (12) through the fixing nut (52) and rotates synchronously with the coupling (12).

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