Low speed electric spindle

Abstract

The application discloses a low-speed electric spindle, relates to the field of electric spindles, and comprises a shell, a stator and a rotor, the two ends of the rotor are provided with a plurality of first rotating members, a limiting ring is sleeved on the first rotating member away from the output end of the rotor, a first bearing cavity matched with the first rotating member is formed in the inner side of the limiting ring, the limiting ring is slidably connected to the shell, a second bearing cavity is formed between the shell and the limiting ring, the second bearing cavity is provided with a second rotating member, an installation cavity is formed between the limiting ring and the shell, a plurality of liquid inlet holes and a plurality of liquid outlet holes are formed in the side of the limiting ring close to the installation cavity, a plurality of cooling circulation cavities are formed in the limiting ring, the two ends of the cooling circulation cavities are respectively communicated with the liquid inlet holes and the liquid outlet holes, a plurality of liquid injection holes and a plurality of liquid outlets are mounted on the shell, and flexible connecting pipes are connected between the liquid injection holes and the liquid outlets and the liquid inlet holes and the liquid outlet holes respectively. The application can reduce the temperature at the bearing, improve the stability of the bearing in use, and ensure the service life of the electric spindle.

Description

Technical Field

[0001] This application relates to the field of electric spindles, and more particularly to a low-speed electric spindle. Background Technology

[0002] Currently, electric spindles are a new technology that integrates machine tool spindles and spindle motors. They are mechatronic products that convert electrical energy transmitted by frequency converters or drive controllers into mechanical energy output from the spindle end, driving various tools or mechanisms to perform high-speed and high-efficiency cutting and rotary motion. They are characterized by low noise, low vibration, and compact structure.

[0003] In the prior art, an electric spindle includes a housing, a stator, and a rotor. Several rotating bearings are provided at both ends of the rotor. A first mounting ring groove is formed on the inner side of the housing near the rotor output end. A limiting ring is slidably connected to the inner side of the housing away from the rotor output end. The limiting ring is slidably arranged along the rotor axis. A second mounting ring groove is formed on the inner side of the limiting ring. The first mounting ring groove and the second mounting ring groove are used to fix the rotating bearings. A water inlet hole and a water outlet hole are provided at one end of the housing. Multiple water-cooling cavities are formed along the length of the housing and are respectively connected to the water inlet hole and the water outlet hole.

[0004] Regarding the aforementioned existing technologies, electric spindles generate heat during operation. Due to thermal expansion and contraction, the rotor moves along its axial direction. The axial movement distance of the rotor is provided by the limiting ring. Existing technologies can only cool the outer casing or the rotor. The limiting ring and the rotating bearing installation point transfer heat between the limiting ring and the outer casing to achieve a cooling effect. However, this method is difficult to achieve effective cooling, affecting the cooling effect of the rotating bearing and reducing the service life of the electric spindle. Improvements are urgently needed. Summary of the Invention

[0005] In order to reduce the temperature at the rotating bearing, improve the stability of the rotating bearing in use, and ensure the service life of the electric spindle, this application provides a low-speed electric spindle.

[0006] This application provides a low-speed electric spindle with the following technical solution: It includes a housing, a stator, and a rotor. Several first rotating parts are provided at both ends of the rotor. A limiting ring is fitted onto the first rotating part away from the rotor output end. A first bearing cavity is formed inside the limiting ring to engage with the first rotating part. The limiting ring is slidably connected to the housing. A second bearing cavity is formed between the housing and the limiting ring. A second rotating part is provided in the second bearing cavity. A mounting cavity is formed between the limiting ring and the housing. Multiple liquid inlets and multiple liquid outlets are formed on the side of the limiting ring near the mounting cavity. Multiple cooling circulation cavities are formed inside the limiting ring. Both ends of the cooling circulation cavities are connected to the liquid inlets and liquid outlets, respectively. Multiple injection holes and multiple outlets are installed on the housing. Flexible connecting pipes connect the injection holes and the outlets to the liquid inlets and outlets, respectively.

[0007] By adopting the above technical solution, during use, cooling liquid is injected into the cooling circulation chamber through the flexible connecting pipe, thereby cooling the limiting ring and allowing direct contact between the limiting ring and the first rotating component for cooling. This better reduces the temperature of the first rotating component, improves the stability of the rotating bearing, and ensures the service life of the electric spindle.

[0008] Preferably, the limiting ring includes a cooling ring, and limiting stop rings are provided on both sides of the cooling ring. The cooling circulation cavity includes an axial cavity opened in the cooling ring. A connecting cavity for connecting two adjacent axial cavities is opened on the side of the limiting stop ring near the cooling ring. A locking groove is opened on the side wall of the limiting stop ring, and a plurality of locking pins are inserted into the locking groove. The locking pins are inserted into and cooperate with the outer shell.

[0009] By adopting the above technical solution and using a splicing structure, assembly can be made more convenient, reducing the complexity of the overall structure, and the first rotating component can be locked more easily, thus improving the stability of the first rotating component in use.

[0010] Preferably, the outer shell has a first injection cavity, the limiting ring has a second injection cavity communicating with the first injection cavity, and the limiting ring has a plurality of third injection cavities, which are respectively connected to the first bearing cavity and the second bearing cavity; the limiting ring has a plurality of first drainage cavities for connecting the first bearing cavity and the second bearing cavity, and the outer shell has a second drainage cavity communicating with the second bearing cavity.

[0011] By adopting the above technical solution, lubricating oil is injected into the first injection chamber, which can better inject the lubricating oil into the first rotating component and the second rotating component. On the one hand, it can make the first rotating component and the second rotating component rotate more smoothly, improving the smoothness of the electric spindle rotation. On the other hand, it can make the heat more stably distributed, ensuring the stability of the first rotating component and the second rotating component.

[0012] Preferably, a partition ring is provided between the plurality of first rotating parts, and mounting ring cavities for fixing the first rotating parts are formed on both sides of the partition ring. The plurality of third injection cavities are respectively connected to the plurality of mounting ring cavities, and a third drainage cavity connected to the first drainage cavity is opened on the partition ring.

[0013] By adopting the above technical solution, the third injection chamber and the third drainage chamber correspond one-to-one, and the lubricating fluid can be replaced separately for each first rotating component, ensuring the replacement effect of lubricating oil in multiple first rotating components and improving the smoothness of rotation of the first rotating components.

[0014] Preferably, a connecting plunger is fixed inside the first injection chamber, the connecting plunger is inserted into and cooperates with the second injection chamber, a sealing ring is provided on the side wall of the connecting plunger, the sealing ring abuts against the inner wall of the second injection chamber, and a connecting column cavity for connecting the first injection chamber and the second injection chamber is formed on the connecting plunger.

[0015] By adopting the above technical solution, during use, the connection can be made through the connecting plunger during the movement of the limit ring, thereby improving the convenience and effectiveness of lubricating oil injection.

[0016] Preferably, the cooling ring sidewall has a clearance cavity, which is located between two adjacent axial cavities and serves to connect the two adjacent axial cavities. A telescopic hole is provided on the side of the clearance cavity near the flexible connecting pipe that is close to the limiting ring. A telescopic rod is telescopically connected within the telescopic hole, and a limiting spring is provided within the telescopic hole to drive the telescopic rod closer to the limiting ring. A guide angle plate is provided at one end of the telescopic rod near the limiting ring, and the guide angle plate is positioned directly opposite the liquid inlet. The guide angle plate is used to uniformly guide the cooling liquid to the two axial cavities. A positioning slot is provided on the limiting ring to engage with the top of the guide angle plate.

[0017] By adopting the above technical solution, during use, inserting the telescopic rod into the telescopic hole and cooperating with the limiting spring can allow the guide plate to be inserted into the positioning slot. Firstly, this allows for more precise positioning of the limiting retaining ring, improving the accuracy of the limiting retaining ring installation. Secondly, it can guide the flow direction of the coolant, reducing the flow resistance of the coolant and improving the smoothness of the coolant flow.

[0018] Preferably, the guide angle plate is composed of two integrally formed guide plates, which are set at an angle. A deformation groove is formed on the inner side of the angle between the two guide plates. The telescopic rod is inserted into the deformation groove. The deformation groove is used to provide deformation space for the two guide plates. A limit stop groove is formed on the side wall of the limiting stop ring. The end of the guide plate away from the telescopic rod abuts against the limit stop groove.

[0019] By adopting the above technical solution, the deformation groove can provide space for the two guide plates to deform. When the guide plate is impacted by the cooling liquid, the guide plate deforms, which can bring the guide plate closer to the axial cavity, reduce the flow resistance, and the guide plate can deform. When the liquid pressure changes, the vibration of the guide plate can reduce the residue of impurities and improve the stability of the cooling liquid flow.

[0020] Preferably, a guide shaft is provided in the communicating cavity away from the flexible connecting pipe, and a guide impeller is rotatably connected to the guide shaft. The guide impeller slides in the communicating cavity along the liquid flow direction. When cooling liquid is injected in the reverse direction, the guide impeller moves in the reverse direction to clean the communicating cavity and the clearance cavity.

[0021] By adopting the above technical solution, the cooling liquid is injected in reverse during use, which makes it easier to clean the internal scale and reduce the impact of clogging the internal space on the heat dissipation of rotating parts; the guide impeller makes it easier to clean the corner of the connecting cavity and the clearance cavity.

[0022] Preferably, a flow-limiting cavity is formed in the first drainage cavity, and a flow-limiting guide wheel is installed in the flow-limiting cavity.

[0023] By adopting the above technical solution, the position of the lubricating oil is limited, reducing the flow between the two chambers, while allowing flow when injecting pressurized lubricating oil.

[0024] Preferably, a positioning cavity is provided at the bottom of the locking groove, the positioning cavity is connected to the communicating cavity, a sealing ring is provided around the locking post, the sealing ring abuts against the side wall of the locking groove, and a positioning insert is provided at the bottom of the locking post, the positioning insert engaging with the clearance cavity.

[0025] By adopting the above technical solution, during use, the positioning block allows the limiting ring and the cooling ring to be more precisely aligned, improving the stability of the limiting ring. The limiting ring moves under the action of the rotor, at which time the positioning block and the limiting ring can move relative to each other, thereby changing the space between the clearance cavity and the connecting cavity. This allows for the cleaning of internal blockages and impurities, reducing the accumulation of scale at corners, providing more space for liquid flow, improving the smoothness of internal cooling liquid flow, and increasing the liquid rate.

[0026] In summary, this application includes at least one of the following beneficial technical effects: 1. During use, coolant is injected into the cooling circulation chamber through a flexible connecting pipe, which can cool the limiting ring and allow the limiting ring to directly contact the first rotating part for cooling, thereby better reducing the temperature of the first rotating part, improving the stability of the rotating bearing, and ensuring the service life of the electric spindle. 2. Lubricating oil is injected through the first injection chamber, which allows the lubricating oil to be injected into the first rotating component and the second rotating component more effectively. On the one hand, this allows the first rotating component and the second rotating component to rotate more smoothly, improving the smoothness of the electric spindle rotation. On the other hand, it allows the heat to be distributed more stably, ensuring the stability of the first rotating component and the second rotating component. 3. By inserting the telescopic rod into the telescopic hole and cooperating with the limiting spring, the guide plate can be inserted into the positioning slot. Firstly, this allows for more precise positioning of the limiting retaining ring, improving the accuracy of the limiting retaining ring installation. Secondly, it can guide the flow direction of the coolant, reducing the flow resistance of the coolant and improving the smoothness of the coolant flow. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the overall structure of a low-speed electric spindle according to an embodiment of this application; Figure 2 for Figure 1 Enlarged schematic diagram of section A of the structure; Figure 3 This is a schematic diagram illustrating the lubricating oil inlet process, which is the main feature of Embodiment 1 of this application. Figure 4 This is a schematic diagram illustrating the structure of the third injection chamber, which is the main feature of Embodiment 1 of this application. Figure 5 This is a schematic diagram of the structure of the guide angle plate and the avoidance cavity, which is the main features of Embodiment 2 of this application; Figure 6 This is a schematic diagram of the structure of the guide shaft and guide impeller, which is the main features of Embodiment 2 of this application. Figure 7 This is a schematic diagram of the structure of the flow-limiting guide wheel and the flow-limiting cavity, which is the main features of Embodiment 2 of this application. Figure 8 This is a schematic diagram of the structure of the positioning block and the positioning cavity, which is the main features of Embodiment 3 of this application. Reference numerals: 1. Outer shell; 2. Stator; 3. Rotor; 4. Mounting cavity; 5. Second drain cavity; 6. First rotating component; 7. Limiting ring; 71. Cooling ring; 72. Limiting retaining ring; 8. Injection hole; 9. Outlet; 10. First injection cavity; 11. Second rotating component; 12. Second bearing cavity; 13. Locking post; 14. First bearing cavity; 15. Inlet hole; 16. Flexible connecting tube; 17. Outlet hole; 18. Axial cavity; 19. Connecting cavity; 20. Connecting post cavity; 21. Connecting plunger; 22. Sealing ring; 23. Second injection chamber; 24. First discharge chamber; 25. Third injection chamber; 26. Limiting groove; 27. Third discharge chamber; 28. Separating ring; 29. ​​Guide angle plate; 30. Limiting compression spring; 31. Telescopic hole; 32. Telescopic rod; 33. Clearance chamber; 34. Deformation groove; 35. Positioning slot; 36. Guide shaft; 37. Guide impeller; 38. Flow limiting guide wheel; 39. Flow limiting chamber; 40. Positioning block; 41. Positioning chamber. Detailed Implementation

[0028] The following is in conjunction with the appendix Figures 1-8 This application will be described in further detail.

[0029] This application discloses a low-speed electric spindle.

[0030] Example 1; Reference Figure 1A low-speed electric spindle includes a housing 1, a stator 2, and a rotor 3. The stator 2 is an integral cylindrical annular structure, and the rotor 3 is a cylindrical laminated structure. Both the stator 2 and the rotor 3 are made of cold-rolled non-oriented silicon steel sheets. Several first rotating parts 6 are installed at both ends of the rotor 3. The first rotating parts 6 are rotary bearings. A limiting ring 7 is sleeved on the first rotating part 6 away from the output end of the rotor 3. The limiting ring is circular. A first bearing cavity 14 is opened on the inner side of the limiting ring 7 to engage with the first rotating part 6. The limiting ring 7 is slidably connected to the housing 1. A second bearing cavity 12 is opened between the housing 1 and the limiting ring 7. The first rotating component 11 is installed, and the limiting ring 7 and the outer shell 1 form an installation cavity 4. Multiple liquid inlet holes 15 and multiple liquid outlet holes 17 are opened on the side of the limiting ring 7 near the installation cavity 4. Multiple cooling circulation chambers are opened inside the limiting ring 7, and the two ends of the cooling circulation chambers are connected to the liquid inlet holes 15 and the liquid outlet holes 17 respectively. Multiple liquid injection holes 8 and multiple liquid outlets 9 are installed on the outer shell 1. Flexible connecting pipes 16 are connected between the liquid injection holes 8 and the liquid outlets 9 and the liquid inlet holes 15 and the liquid outlet holes 17 respectively. The flexible connecting pipes 16 are made of stainless steel braided corrugated tubing with a circular through-hole cross-section and smooth inner walls to reduce flow resistance. During use, coolant is injected into the cooling circulation chambers through the flexible connecting pipes 16, thereby cooling the limiting ring 7 and allowing direct contact between the limiting ring 7 and the first rotating component 6 for cooling. This better reduces the temperature of the first rotating component 6, improves the stability of the rotating bearing, and ensures the service life of the electric spindle.

[0031] Reference Figure 2 The limiting ring 7 includes a cooling ring 71, which is circular in shape. Limiting retaining rings 72, also circular in shape, are installed on both sides of the cooling ring 71. The cooling circulation chamber includes an axial cavity 18 formed within the cooling ring 71. A connecting cavity 19 for connecting two adjacent axial cavities 18 is formed on the side of the limiting retaining ring 72 near the cooling ring 71. A locking groove is formed on the side wall of the limiting retaining ring 72, and multiple locking pins 13 are inserted into the locking groove, engaging with the outer shell 1. This modular structure allows for easier assembly, reduces the overall structural complexity, and facilitates easier locking of the first rotating component 6, improving its stability.

[0032] Reference Figure 3The outer casing 1 has a first injection chamber 10, and the limiting ring 7 has a second injection chamber 23 connected to the first injection chamber 10. The limiting ring 7 also has multiple third injection chambers 25, which are respectively connected to the first bearing chamber 14 and the second bearing chamber 12. The limiting ring 7 has multiple first drainage chambers 24 for connecting the first bearing chamber 14 and the second bearing chamber 12, and the outer casing 1 has a second drainage chamber 5 connected to the second bearing chamber 12. Lubricating oil is injected through the first injection chamber 10, which allows for better lubrication of the first rotating component 6 and the second rotating component 11. This enables the first rotating component 6 and the second rotating component 11 to rotate more smoothly, improving the fluidity of the electric spindle rotation. Furthermore, it allows for more stable heat dissipation, ensuring the stability of the first rotating component 6 and the second rotating component 11.

[0033] Reference Figure 4 A partition ring 28 is installed between multiple first rotating parts 6. The partition ring 28 has mounting ring cavities formed on both sides for fixing the first rotating parts 6. Multiple third injection chambers 25 are respectively connected to the multiple mounting ring cavities. A third drainage chamber 27 is opened on the partition ring 28 and is connected to the first drainage chamber 24. The third injection chamber 25 and the third drainage chamber 27 correspond one-to-one, allowing for the separate replacement of lubricating fluid in each first rotating part 6, ensuring the effective replacement of lubricating oil in the multiple first rotating parts 6, and improving the smoothness of the rotation of the first rotating parts 6.

[0034] A connecting plunger 21 is fixed inside the first injection chamber 10. The connecting plunger 21 is inserted into and fitted into the second injection chamber 23. A sealing ring 22 is installed on the side wall of the connecting plunger 21, and the sealing ring 22 abuts against the inner wall of the second injection chamber 23. A connecting cavity 20 for connecting the first injection chamber 10 and the second injection chamber 23 is formed on the connecting plunger 21. During use, the connection can be made through the connecting plunger 21 while the limiting ring 7 is moving, improving the convenience and effectiveness of injecting lubricating oil.

[0035] The implementation principle of a low-speed electric spindle in this application embodiment is as follows: the electric spindle is rotated by the stator 2 and the rotor 3. Cooling liquid is injected into the cooling circulation chamber through the flexible connecting pipe 16, thereby cooling the limiting ring 7 and allowing the limiting ring 7 to directly contact the first rotating component 6 for cooling, thus better reducing the temperature of the first rotating component 6. Lubricating oil is injected through the first injection chamber 10, thereby better injecting lubricating oil into the first rotating component 6 and the second rotating component 11. On the one hand, this allows the first rotating component 6 and the second rotating component 11 to rotate more smoothly, improving the smoothness of the electric spindle rotation. On the other hand, it allows the heat to be more stably distributed, ensuring the stability of the first rotating component 6 and the second rotating component 11, and ensuring the service life of the electric spindle.

[0036] Example 2; Reference Figure 5 The difference between this embodiment and embodiment 1 is that the cooling ring 71 has a clearance cavity 33 on its side wall. The clearance cavity 33 is located between two adjacent axial cavities 18 and is used to connect the two adjacent axial cavities 18. The clearance cavity 33 near the flexible connecting pipe 16 has a telescopic hole 31 on the side near the limiting ring 72. A telescopic rod 32 is telescopically connected in the telescopic hole 31. A limiting spring 30 for driving the telescopic rod 32 to approach the limiting ring 72 is installed in the telescopic hole 31. A guide angle plate 29 is installed at the end of the telescopic rod 32 near the limiting ring 72. The guide angle plate 29 is set directly opposite the liquid inlet hole 15. The guide angle plate 29 is used to guide the cooling liquid evenly to the two axial cavities 18. The limiting ring 72 has a positioning slot 35 that is inserted and matched with the top of the guide angle plate 29. During use, inserting the telescopic rod 32 into the telescopic hole 31, along with the limiting spring 30, allows the guide plate 29 to be inserted into the positioning slot 35. This firstly allows for more precise installation and positioning of the limiting retaining ring 72, improving the accuracy of its installation. Secondly, it guides the flow direction of the coolant, reducing the flow resistance of the coolant and improving its smoothness.

[0037] The guide plate 29 consists of two integrally formed guide plates set at an angle. A deformation groove 34 is formed on the inner side of the angle between the two guide plates. The telescopic rod 32 is inserted into the deformation groove 34, which provides deformation space for the two guide plates. A limiting retaining ring 72 has a limiting retaining groove 26 on its side wall, and the end of the guide plate away from the telescopic rod 32 abuts against the limiting retaining groove 26. The deformation groove 34 provides deformation space for the two guide plates. When the guide plate is impacted by the cooling liquid, the deformation allows it to move closer to the axial cavity 18, reducing flow resistance. Furthermore, the deformation of the guide plate, combined with changes in liquid pressure, reduces impurity residue and improves the stability of the cooling liquid flow.

[0038] Reference Figure 6 A guide shaft 36 is installed in the connecting cavity 19, away from the flexible connecting pipe 16. The guide shaft 36 is cylindrical, and a guide impeller 37 is rotatably connected to the guide shaft 36. The guide impeller 37 is a closed disc structure. The guide impeller 37 slides in the direction of liquid flow within the connecting cavity 19. When coolant is injected in the reverse direction, the guide impeller 37 moves in the opposite direction to clean the connecting cavity 19 and the clearance cavity 33. During use, the reverse injection of coolant makes it easier to clean the internal scale and reduces the impact of clogging the internal space on the heat dissipation of rotating parts. The guide impeller 37 also makes it easier to clean the corners of the connecting cavity 19 and the clearance cavity 33.

[0039] Reference Figure 7A flow-limiting chamber 39 is formed within the first liquid chamber 24, and a flow-limiting guide wheel 38, which is a centrifugal impeller, is installed within the flow-limiting chamber 39. This limits the position of the lubricating oil, reducing the flow between the two chambers, while allowing flow when pressurized lubricating oil is injected.

[0040] The implementation principle of Example 2 is as follows: During use, inserting the telescopic rod 32 into the telescopic hole 31 and cooperating with the limiting spring 30 can allow the guide plate 29 to be inserted into the positioning slot 35, which can make the installation and positioning of the limiting retaining ring 72 more accurate. The deformation groove 34 can provide deformation space for the two guide plates. When the guide plate is impacted by the cooling liquid, the guide plate deforms, which can make the guide plate closer to the axial cavity 18, reduce the flow resistance, improve the stability of the rotating bearing, and ensure the service life of the electric spindle.

[0041] Example 3; Reference Figure 8 The difference between this embodiment and embodiment 1 is that a positioning cavity 41 is provided at the bottom of the locking groove, the positioning cavity 41 is connected to the communicating cavity 19, a sealing ring is installed around the locking post 13, the sealing ring abuts against the side wall of the locking groove, a positioning plug 40 is installed at the bottom of the locking post 13, the positioning plug 40 is inserted into the clearance cavity 33, and the positioning plug 40 is used to precisely align the limiting ring 72 and the cooling ring 71.

[0042] The implementation principle of Example 3 is as follows: During use, the positioning block 40 allows the limiting ring 72 and the cooling ring 71 to be more precisely aligned, improving the stability of the limiting ring fixation. The limiting ring 72 moves under the action of the rotor 3. At this time, the positioning block 40 and the limiting ring 72 can move relative to each other, thereby changing the space between the clearance cavity 33 and the connecting cavity 19. This allows for the cleaning of internal blockages and impurities, reducing the accumulation of scale at corners, providing more space for liquid flow, improving the smoothness of internal cooling liquid flow, and increasing the liquid rate.

[0043] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A low-speed electric spindle, characterized in that: The device includes a housing (1), a stator (2), and a rotor (3). Both ends of the rotor (3) are provided with several first rotating parts (6). A limiting ring (7) is fitted onto the first rotating part (6) furthest from the output end of the rotor (3). A first bearing cavity (14) is formed inside the limiting ring (7) to engage with the first rotating part (6). The limiting ring (7) is slidably connected to the housing (1). A second bearing cavity (12) is formed between the housing (1) and the limiting ring (7). A second rotating part (11) is disposed within the second bearing cavity (12). The limiting ring… (7) A mounting cavity (4) is formed between the limiting ring (7) and the outer shell (1). The limiting ring (7) has multiple liquid inlet holes (15) and multiple liquid outlet holes (17) on the side near the mounting cavity (4). Multiple cooling circulation cavities are formed inside the limiting ring (7). The two ends of the cooling circulation cavities are connected to the liquid inlet holes (15) and the liquid outlet holes (17) respectively. Multiple liquid injection holes (8) and multiple liquid outlets (9) are installed on the outer shell (1). Flexible connecting pipes (16) are connected between the liquid injection holes (8) and the liquid outlets (9) and the liquid inlet holes (15) and the liquid outlet holes (17) respectively.

2. A low-speed electric spindle according to claim 1, characterized in that: The limiting ring (7) includes a cooling ring (71), and limiting stop rings (72) are provided on both sides of the cooling ring (71). The cooling circulation cavity includes an axial cavity (18) opened in the cooling ring (71). The limiting stop ring (72) has a connecting cavity (19) for connecting two adjacent axial cavities (18) on the side near the cooling ring (71). The side wall of the limiting stop ring (72) has a locking groove, and a plurality of locking pins (13) are inserted into the locking groove. The locking pins (13) are inserted into the outer shell (1).

3. A low-speed electric spindle according to claim 2, characterized in that: The outer shell (1) has a first injection cavity (10), the limiting ring (7) has a second injection cavity (23) connected to the first injection cavity (10), the limiting ring (7) has a plurality of third injection cavities (25), the plurality of third injection cavities (25) are respectively connected to the first bearing cavity (14) and the second bearing cavity (12); the limiting ring (7) has a plurality of first drainage cavities (24) for connecting the first bearing cavity (14) and the second bearing cavity (12), and the outer shell (1) has a second drainage cavity (5) connected to the second bearing cavity (12).

4. A low-speed electric spindle according to claim 3, characterized in that: A partition ring (28) is provided between multiple first rotating parts (6). The partition ring (28) has mounting ring cavities formed on both sides for fixing the first rotating parts (6). Multiple third injection cavities (25) are respectively connected to multiple mounting ring cavities. A third drainage cavity (27) is opened on the partition ring (28) and is connected to the first drainage cavity (24).

5. A low-speed electric spindle according to claim 4, characterized in that: A connecting plunger (21) is fixed inside the first injection chamber (10). The connecting plunger (21) is inserted into the second injection chamber (23). A sealing ring (22) is provided on the side wall of the connecting plunger (21). The sealing ring (22) abuts against the inner wall of the second injection chamber (23). A connecting plunger cavity (20) for connecting the first injection chamber (10) and the second injection chamber (23) is opened on the connecting plunger (21).

6. A low-speed electric spindle according to claim 2, characterized in that: The cooling ring (71) has a clearance cavity (33) on its side wall. The clearance cavity (33) is located between two adjacent axial cavities (18) and is used to connect the two adjacent axial cavities (18). The clearance cavity (33) near the flexible connecting pipe (16) has a telescopic hole (31) on the side near the limiting ring (72). A telescopic rod (32) is telescopically connected in the telescopic hole (31). A device for driving is provided in the telescopic hole (31). The telescopic rod (32) is moved close to the limiting spring (30) of the limiting ring (72). A guide plate (29) is provided at one end of the telescopic rod (32) close to the limiting ring (72). The guide plate (29) is positioned directly opposite the liquid inlet (15). The guide plate (29) is used to guide the cooling liquid evenly to the two axial cavities (18). The limiting ring (72) is provided with a positioning slot (35) that is inserted and engaged with the top of the guide plate (29).

7. A low-speed electric spindle according to claim 6, characterized in that: The guide angle plate (29) is composed of two integrally formed guide plates. The two guide plates are set at an angle. A deformation groove (34) is opened on the inner side of the angle between the two guide plates. The telescopic rod (32) is inserted into the deformation groove (34). The deformation groove (34) is used to provide deformation space for the two guide plates. A limit stop groove (26) is opened on the side wall of the limiting stop ring (72). The end of the guide plate away from the telescopic rod (32) abuts against the limit stop groove (26).

8. A low-speed electric spindle according to claim 6, characterized in that: A guide shaft (36) is provided in the communicating cavity (19) away from the flexible connecting pipe (16). A guide impeller (37) is rotatably connected to the guide shaft (36). The guide impeller (37) slides in the communicating cavity (19) along the liquid flow direction. When the cooling liquid is injected in the opposite direction, the guide impeller (37) moves in the opposite direction to clean the communicating cavity (19) and the clearance cavity (33).

9. A low-speed electric spindle according to claim 8, characterized in that: A flow-limiting cavity (39) is formed in the first drainage cavity (24), and a flow-limiting guide wheel (38) is installed in the flow-limiting cavity (39).

10. A low-speed electric spindle according to claim 9, characterized in that: The bottom of the locking groove is provided with a positioning cavity (41), which is connected to the communicating cavity (19). A sealing ring is provided around the locking post (13), which abuts against the side wall of the locking groove. A positioning plug (40) is provided at the bottom of the locking post (13), which is inserted into the clearance cavity (33).

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