A milling machine electric spindle structure for zirconia ceramic part machining

Abstract

This application relates to the field of metal forming machine tools, and in particular to a milling machine electric spindle structure for machining zirconia ceramic parts. The structure includes a housing, a drive mechanism, a transmission mechanism, a rotating mechanism, and a pressure relief mechanism. The rotating mechanism includes a spindle, a bushing, ball bearings, and a sealing structure. The spindle is fixed to the output end of the transmission mechanism. The bushing is fitted onto the outer wall of the spindle, and ball bearings abut against the outer wall of the spindle at both ends of the bushing. A cavity is formed between the spindle and the bushing. Sealing structures for sealing the cavity are provided at both ends of the bushing and between the bushing and the spindle. A pressure relief hole is provided through the bushing, connecting the cavity. The housing has a through hole, and the pressure relief hole and through hole are sealed and connected to the pressure relief mechanism. The pressure relief mechanism monitors and adjusts the air pressure in the cavity through the pressure relief hole. Milling machines using this electric spindle structure can achieve high rotational stability, machining accuracy, speed, and sealing performance during the machining of zirconia ceramic parts.

Description

Technical Field

[0001] This application relates to the field of forming ultra-precision machining tools, and in particular to a milling machine electric spindle structure for machining zirconia ceramic parts. Background Technology

[0002] Advanced ceramics, manufactured through molding and sintering processes, have become an indispensable key material in high-end manufacturing due to their high hardness, wear resistance, high temperature resistance, corrosion resistance, low coefficient of thermal expansion, and excellent insulation properties. Their main materials include zirconium oxide, alumina, and silicon nitride, and they are widely used in strategic industries such as aerospace, military nuclear energy, precision machinery, electronic semiconductors, and biomedicine. Especially in the field of ultra-precision machining, advanced ceramic components have gradually replaced traditional metal materials, becoming the preferred solution for core functional parts. However, while advanced ceramic materials possess superior performance, their high hardness also makes machining extremely difficult, placing more stringent requirements on the rigidity, speed, thermal stability, and sealing performance of milling machine electric spindles.

[0003] Existing milling machine electric spindle structures typically include a drive motor, a transmission mechanism, and a rotating mechanism. The rotating mechanism includes a spindle, bushing, bearings, sleeve, and seals. The transmission mechanism uses belt pulleys or gear sets to transmit the motor's rotation to the spindle, driving its rotation. A bushing is installed on the outer wall of the spindle, and a ball bearing is installed between the spindle and the bushing. The end of the spindle is connected to the sleeve by locking bolts and sealed with a sealing ring. The ball bearing reduces friction during spindle rotation, thus lowering energy consumption. Furthermore, by adjusting the preload of the ball bearing, backlash can be further eliminated, spindle rigidity enhanced, vibration reduced, and spindle rotational accuracy improved, thereby increasing the rotational speed to some extent. The sealing ring structure at the spindle end can, to some extent, prevent oil and coolant from entering the gap between the spindle and the bushing, avoiding the impact of oil on the spindle's rotational accuracy.

[0004] However, existing electric spindle structures for milling machines exhibit significant drawbacks during long-term operation. These drawbacks primarily manifest in the fact that, due to the completely sealed gap between the spindle and the bushing, the air in the gap expands as the spindle rotates and generates heat, creating internal high pressure. This high pressure affects the preload between the ball bearings and the spindle, leading to a significant reduction in machining accuracy. Especially after prolonged operation, the vibration of the machining head becomes increasingly pronounced, and oil leakage into the gap persists, severely impacting the performance and lifespan of the electric spindle structure and hindering the efficiency and quality of advanced ceramic precision machining. Summary of the Invention

[0005] To meet the requirements of advanced ceramic ultra-precision machining for the rotational stability, machining accuracy, speed and sealing of electric spindles, this application provides a milling machine electric spindle structure for machining zirconia ceramic parts.

[0006] An electric spindle structure for milling milling machines used for machining zirconia ceramic parts includes a housing and a drive mechanism, a transmission mechanism, and a rotating mechanism disposed within the housing. The drive mechanism drives the transmission mechanism to rotate the rotating mechanism. The structure also includes a pressure relief mechanism. The rotating mechanism includes a spindle, a bushing, ball bearings, and a sealing structure. The spindle is rotatably mounted on the housing and fixedly connected to the output end of the transmission mechanism. The bushing is fitted onto the outer wall of the spindle, and the outer wall of the bushing is fixed inside the housing. At least one ball bearing abuts against the inner wall of the bushing at each end and the outer wall of the spindle. A chamber is formed between the spindle and the bushing. Sealing structures are provided between the two ends of the bushing and the spindle to seal the chamber. A pressure relief hole communicating with the chamber is provided through the bushing. A through-hole is provided on the housing corresponding to the pressure relief hole. The pressure relief hole and the through-hole are sealed and communicate with the pressure relief mechanism. The pressure relief mechanism monitors and adjusts the air pressure in the chamber through the pressure relief hole.

[0007] By adopting the above technical solution, ball bearings are installed at both ends of the bushing and between the main shaft, forming a "fixed at both ends" support structure. During high-speed rotation, this dual-bearing structure reduces the radial and axial runout of the main shaft, lowers the vibration amplitude, effectively disperses the force on the main shaft, avoids bending deformation caused by uneven force distribution when supported at one end, and significantly improves the bending rigidity and vibration resistance of the main shaft.

[0008] A pressure relief hole, communicating with the chamber, is provided through the bushing. A through hole is provided on the chassis corresponding to the pressure relief hole, and the pressure relief hole and through hole are sealed and connected to the pressure relief mechanism, allowing the pressure relief mechanism to monitor the air pressure in the chamber through the pressure relief hole. When the spindle rotates and generates heat, causing the air in the chamber to expand and form internal high pressure, the pressure relief mechanism can adjust the chamber air pressure in time to prevent the internal high pressure from affecting the preload between the ball bearing and the spindle, thereby ensuring the rigidity and rotational accuracy of the spindle and reducing the vibration of the machining head. At the same time, because the chamber is in a high-pressure environment, the sealing structure at both ends is prone to failure under high pressure. The technical solution of this application solves the problem of high pressure in the internal environment, ensuring that the sealing structure at both ends maintains good sealing performance during the machining process, and preventing oil and coolant from leaking into the chamber due to high pressure. In summary, when milling milling machines using the electric spindle structure of this application are machining zirconia ceramic parts with high hardness, the rotational stability, machining accuracy, speed, and sealing performance of the electric spindle are further improved, especially during long-term operation, the advantages of milling machine machining are more obvious.

[0009] Preferably, the pressure relief mechanism includes a pressure sensor and a pressure regulating component. The pressure sensor is disposed on the inner wall of the bushing and is used to monitor the air pressure in the chamber. The pressure regulating component adjusts the air pressure in the chamber according to the air pressure data monitored by the pressure sensor.

[0010] By adopting the above technical solution, a pressure sensor installed on the inner wall of the bushing can monitor the air pressure in the chamber between the spindle and the bushing in real time. When the spindle rotates and generates heat, causing the air in the chamber to expand and form internal high pressure, the pressure sensor can promptly acquire the air pressure data and feed it back to the air pressure regulation component. The air pressure regulation component adjusts the chamber air pressure according to this air pressure data, preventing the internal high pressure from affecting the preload between the ball bearing and the spindle, thereby ensuring the spindle's rotational accuracy and machining accuracy, reducing machining head vibration, and preventing oil leakage into the gap, thus improving the performance and service life of the electric spindle structure.

[0011] Preferably, the air pressure regulating assembly includes a sealing tube, an air pump, and a solenoid valve. The sealing tube passes through the through hole and the pressure relief hole in sequence and communicates with the chamber. The air pump is sealed to the sealing tube. The solenoid valve is disposed in the sealing tube and is used to control the entry and exit of gas.

[0012] By adopting the above technical solution, the sealing tube is sequentially connected to the chamber through through-holes and pressure relief holes. The air pump is sealed to the sealing tube, and a solenoid valve is installed in the sealing tube to control the inlet and outlet of gas. When the spindle rotates and generates heat, causing the air in the chamber to expand and form internal high pressure, the pressure sensor detects the pressure change. At this time, the solenoid valve can be opened, and the air pump can be used to discharge the high-pressure gas in the chamber through the sealing tube, reducing the air pressure in the chamber and preventing the internal high pressure from affecting the preload between the ball bearing and the spindle, thereby preventing a decrease in machining accuracy. At the same time, when the air pressure in the chamber is too low, the air pump can also be used to fill the chamber with air to keep the air pressure in the chamber stable, ensuring the performance and service life of the electric spindle structure.

[0013] Preferably, the outer wall of the spindle is tapered, the inner surface of the ball bearing is tapered to match the outer wall of the spindle, and the diameter of the spindle gradually decreases from top to bottom.

[0014] By adopting the above technical solution, the outer wall of the spindle is tapered, and the inner surface of the ball bearing has a matching tapered shape, with the spindle diameter gradually decreasing from top to bottom. This structure allows the ball bearing to better fit the spindle during assembly, enhancing the tightness of the contact between the two. When the spindle rotates, vibration can be reduced more effectively, while improving the spindle's rotational accuracy, thereby enhancing the overall performance and machining accuracy of the electric spindle structure.

[0015] Preferably, the taper of the spindle is 1:20-1:12.

[0016] By adopting the above technical solution, the spindle taper is set within the range of 1:20 to 1:12, resulting in a tighter fit between the spindle and the ball bearing. Because the inner surface of the ball bearing has a taper that matches the outer wall of the spindle, this suitable taper allows the ball bearing to better conform to the spindle, effectively reducing the clearance between them and thus enhancing the spindle's rigidity. This increased rigidity reduces spindle vibration during rotation, improves spindle rotational accuracy, and ultimately contributes to improving the machining accuracy of the milling machine.

[0017] Preferably, the inner wall of the bushing is provided with a limiting groove, and the ball bearing is disposed in the limiting groove and abuts against the groove wall to restrict the vertical movement of the limiting groove.

[0018] By adopting the above technical solution, a limiting groove is provided on the inner wall of the bushing, and the ball bearing is placed in the limiting groove and pressed against the groove wall, which can restrict the vertical movement of the ball bearing. In this way, the position of the ball bearing between the spindle and the bushing can be kept stable, and the preload between the ball bearing and the spindle can be prevented from changing due to vertical movement. This further eliminates clearance, enhances the rigidity of the spindle, reduces vibration, improves the rotational accuracy of the spindle, and thus increases the rotational speed. At the same time, it is also beneficial to improve the machining accuracy and performance of the electric spindle structure and extend its service life.

[0019] Preferably, the outer wall of the bushing is provided with a cooling channel, which is connected to the cooling and lubrication system of the milling machine for circulating coolant to the cooling channel, and the pressure relief hole is arranged to avoid the cooling channel.

[0020] By adopting the above technical solution, a cooling channel is opened on the outer wall of the bushing and connected to the cooling and lubrication system of the milling machine. Coolant can be circulated to the cooling channel, and the coolant flowing within it can carry away the heat generated by the spindle rotation, reducing the bushing temperature and preventing deformation due to overheating. This ensures the fit accuracy between the bushing and the spindle, thereby improving the machining accuracy of the electric spindle structure. Simultaneously, the pressure relief hole is designed to avoid interference from the cooling channel, preventing the coolant from affecting the pressure relief hole. This allows the pressure relief mechanism to properly monitor and regulate the air pressure in the chamber between the spindle and the bushing, maintaining stable air pressure within the chamber and reducing the impact of internal high pressure on the preload between the ball bearing and the spindle, further improving the performance and service life of the electric spindle structure.

[0021] Preferably, the sealing structure includes a sleeve, a locking bolt, and a sealing ring. The sleeve is fastened to the end of the sleeve shaft and the main shaft by the locking bolt, and the sealing ring is disposed between the sleeve and the main shaft to seal the chamber.

[0022] By adopting the above technical solution, the sleeve is fastened to the end of the bushing and the spindle by locking bolts, which can make the connection between the sleeve, bushing and spindle tight. At the same time, a sealing ring is set between the sleeve and the spindle. This double sealing structure can effectively improve the sealing performance of the chamber, prevent oil and coolant from entering the gap between the spindle and bushing, avoid oil from affecting the rotational accuracy of the spindle, thereby ensuring the machining accuracy and stability of the electric spindle structure and extending the service life of the electric spindle structure.

[0023] Preferably, the transmission mechanism includes a first rotating shaft, a second rotating shaft, a first gear set, a second gear set, and a third gear set. The output end of the drive mechanism is fixedly connected to the first rotating shaft. The first gear set is coaxially fixed to the outer wall of the first rotating shaft. The second rotating shaft is coaxially rotatably disposed on the housing. The second gear set is coaxially fixed to the outer wall of the second rotating shaft. The third gear set is coaxially fixed to the outer wall of the main shaft. The first gear set, the second gear set, and the third gear set mesh externally in sequence.

[0024] By adopting the above technical solution, the power of the drive mechanism is transmitted to the first gear set through the first rotating shaft. The first gear set meshes externally with the second gear set. Specifically, the first gear set and the second gear set are a combination of upper and lower gears fixed on the same axis. The power is transmitted to the second gear set on the second rotating shaft. Then, the second gear set meshes externally with the third gear set, transmitting the power to the third gear set on the main shaft, thereby driving the main shaft to rotate. This multi-stage gear transmission method can accurately transmit the power of the drive mechanism to the main shaft. Gear transmission has the advantage of high transmission efficiency, which can reduce power loss during transmission and improve the energy utilization efficiency of the electric spindle structure. At the same time, gear transmission has good stability, which can ensure the stable rotation of the main shaft, thereby improving the stability and accuracy of milling cutter cutting operations and contributing to the improvement of the quality of processed products.

[0025] Preferably, the transmission mechanism is a straight shaft, one end of which is fixedly connected to the output end of the drive mechanism, and the other end is fixedly connected to the main shaft.

[0026] By adopting the above technical solution, the transmission mechanism uses a straight shaft to directly connect the output end of the drive mechanism to the main shaft, eliminating belt pulley transmission and gear transmission methods, which has significant advantages. Specifically: belt transmission is limited by the elastic slippage between the belt and the hub, resulting in low transmission efficiency, and slippage is prone to occur at high speeds, creating a significant bottleneck in speed increase; while gear transmission eliminates the slippage problem, meshing friction and inter-tooth impact are unavoidable during gear meshing, and the transmission ratio of the gear set still limits the final output speed, making it difficult to meet the requirements of ultra-high-speed rotation. In contrast, this solution uses a rigid straight shaft connection, where the output torque of the drive mechanism is directly transmitted to the main shaft without intermediate losses. There is no elastic slippage loss from the belt, nor friction loss and transmission ratio limitation from gear meshing. Therefore, under the same driving conditions, the main shaft speed achievable by the straight shaft transmission is higher than that of the gear transmission, thereby significantly improving the limit speed and response speed of the electric spindle, providing better speed assurance for the efficient and precise machining of advanced ceramics and other high-hardness and brittle materials.

[0027] In summary, this application includes at least one of the following beneficial technical effects: 1. By installing ball bearings at both ends of the bushing and between the bushing and the spindle, the rotational accuracy between the bushing and the ball bearings can be improved. Combined with the pressure relief hole on the bushing, which is connected to a pressure relief mechanism, the pressure sensor of the pressure relief mechanism can monitor the air pressure in the chamber between the spindle and the bushing. The air pressure adjustment component of the pressure relief mechanism can adjust the chamber air pressure according to the monitoring data, which can prevent the air in the chamber from expanding and forming high pressure due to the heat generated by the spindle rotation. This prevents the high pressure from affecting the preload between the ball bearing and the spindle, thereby improving the machining accuracy. 2. The outer wall of the spindle and the inner surface of the ball bearing have matching tapers. This matching taper design makes the fit between the spindle and the ball bearing tighter, which can further enhance the rigidity of the spindle, reduce vibration, and thus further improve the rotational accuracy of the spindle. Attached Figure Description

[0028] Figure 1 This is a cross-sectional view of a milling machine electric spindle structure for machining zirconia ceramic parts, as described in Example 1. Figure 2 This is a schematic diagram of the installation of an electric spindle structure for milling a zirconia ceramic part in Example 1.

[0029] Explanation of reference numerals in the attached drawings: 1. Chassis; 11. Through hole; 2. Drive mechanism; 3. Transmission mechanism; 31. First rotating shaft; 32. Second rotating shaft; 33. First gear set; 34. Second gear set; 35. Third gear set; 4. Rotating mechanism; 41. Main shaft; 42. Bushing; 421. Limiting groove; 422. Cooling channel; 423. Pressure relief hole; 43. Ball bearing; 44. Sealing structure; 441. Sleeve; 442. Locking bolt; 443. Sealing ring; 45. Chamber; 5. Pressure relief mechanism; 51. Pressure sensor; 52. Air pressure regulating component; 521. Sealing pipe; 522. Air pump; 523. Solenoid valve. Detailed Implementation

[0030] The following is in conjunction with the appendix Figure 1-2 This application will be described in further detail. Example 1

[0031] This application provides an embodiment of a milling machine electric spindle structure for machining zirconia ceramic parts, referring to... Figure 1 It includes a chassis 1 and a drive mechanism 2, a transmission mechanism 3, a rotating mechanism 4 and a pressure relief mechanism 5 disposed in the chassis 1. The drive mechanism 2 drives the transmission mechanism 3 to rotate the rotating mechanism 4, and the pressure relief mechanism 5 is used to adjust the internal air pressure of the rotating mechanism 4.

[0032] The drive mechanism 2 can be a motor or a servo motor. In this embodiment, a 220V 1.5KW servo motor is preferred. The speed can be freely set from 0 to 36000 RPM to grind different products at different speeds, thereby drilling holes of various sizes.

[0033] Specifically, the transmission mechanism 3 in this embodiment includes a first rotating shaft 31, a second rotating shaft 32, a first gear set 33, a second gear set 34, and a third gear set 35. The output end of the drive mechanism 2 is fixedly connected to the first rotating shaft 31. When the drive mechanism 2 is started, it drives the first rotating shaft 31 to rotate. The first gear set 33 is coaxially fixed to the outer wall of the first rotating shaft 31, so when the first rotating shaft 31 rotates, it drives the first gear set 33 to rotate. The second rotating shaft 32 is coaxially rotatably mounted on the housing 1. The second gear set 34 is coaxially fixed to the outer wall of the second rotating shaft 32. When the first gear set 33 rotates, it drives the second gear set 34, which meshes with it, to rotate, thereby driving the second rotating shaft 32 to rotate. The third gear set 35 is coaxially fixed to the outer wall of the main shaft 41, a key component of the rotating mechanism 4. When the second gear set 34 rotates, it drives the third gear set 35, which meshes with it, to rotate, thereby driving the main shaft 41 to rotate. Through this gear transmission method, the power of the drive mechanism 2 is transmitted to the main shaft 41 of the rotating mechanism 4, driving the main shaft 41 to rotate. The gear set here can be a cylindrical gear set or a bevel gear set, both of which can achieve efficient power transmission.

[0034] Specifically, the rotating mechanism 4 in this embodiment includes a spindle 41, a bushing 42, a ball bearing 43, and a sealing structure 44. The spindle 41 is rotatably mounted on the housing 1 via the rotating bearing. The output end of the transmission mechanism 3 is fixedly connected to the spindle 41 and drives the spindle 41 to rotate around the vertical axis. When the transmission mechanism 3 is running, it transmits power to the spindle 41. The spindle 41, as the core component of the rotation, drives the milling cutter to complete the cutting operation.

[0035] The bushing 42 is fitted onto the outer wall of the main shaft 41, forming a chamber 45 between the main shaft 41 and the bushing 42. The bushing 42 is detachably fixed to the inside of the housing 1 by bolts, ensuring that the outer wall of the bushing 42 is tightly fitted to the housing 1, thus protecting and supporting the main shaft 41. The inner wall of the bushing 42 is provided with limiting grooves 421. Two vertically arranged ball bearings 43 abut against the outer wall of the main shaft 41 at each end of the bushing 42. Each limiting groove 421 accommodates two ball bearings 43, and the ball bearings 43 are tightly pressed against the groove wall. When the main shaft 41 rotates, the ball bearings 43 roll accordingly. The limiting grooves 421 restrict the vertical movement of the ball bearings 43, ensuring stable operation. The ball bearings 43 can be angular contact ball bearings or deep groove ball bearings, both of which have high rotational accuracy and load-bearing capacity.

[0036] The bushing 42 has a cooling channel 422 on its outer wall. The cooling channel 422 is connected to the cooling and lubrication system of the milling machine. The cooling channel 422 is a disc-shaped structure wrapped around the outer wall of the bushing 42. The outlet of the cooling channel 422 faces the worktable. The cooling and lubrication system of the milling machine will circulate the coolant to the cooling channel 422. The coolant flows in the cooling channel 422, carrying away the heat generated by the bushing 42 and the spindle 41, reducing the temperature and improving the service life of the spindle 41.

[0037] The bushing 42 has sealing structures 44 at both ends and between the bushing 42 and the spindle 41 to seal the chamber 45. Each sealing structure 44 includes a sleeve 441, a locking bolt 442, and a sealing ring 443. The sleeve 441 is fastened to the end of the bushing 42 and the spindle 41 by the locking bolt 442. When the locking bolt 442 is tightened, the sleeve 441 is tightly fixed between the end of the bushing 42 and the spindle 41. The sealing ring 443 is located between the sleeve 441 and the spindle 41 to seal the chamber 45, preventing oil and coolant from entering the chamber 45 and affecting the rotational accuracy of the spindle 41. The sealing ring 443 can be a rubber sealing ring or a fluororubber sealing ring, which have good sealing performance and oil resistance.

[0038] Specifically, the outer wall of the spindle 41 is tapered, and the inner surface of the ball bearing 43 has a tapered shape that matches the outer wall of the spindle 41. The diameter of the spindle 41 gradually decreases from top to bottom. This tapered design allows the ball bearing 43 to better fit with the spindle 41, improving the rotational accuracy and stability of the spindle 41. The taper of the spindle 41 is typically 1:20 - 1:12, but in practical applications, the taper can be adjusted according to specific requirements.

[0039] Furthermore, the bushing 42 is provided with a pressure relief hole 423 communicating with the chamber 45. The chassis 1 has a through hole 11 at the position corresponding to the pressure relief hole 423. The pressure relief hole 423 and the through hole 11 are in sealed communication with the pressure relief mechanism 5. The pressure relief hole 423 is arranged to avoid the cooling channel 422, so as to prevent coolant from entering the pressure relief hole 423 and affecting the normal operation of the pressure relief mechanism 5.

[0040] The pressure relief mechanism 5 includes a pressure sensor 51 and a pressure regulating component 52. The pressure sensor 51 is installed on the inner wall of the bushing 42, constantly monitoring the air pressure in the chamber 45 and transmitting the air pressure data to the pressure regulating component 52. The pressure regulating component 52 adjusts the air pressure in the chamber 45 based on the air pressure data monitored by the pressure sensor 51. The pressure regulating component 52 includes a sealing pipe 521, an air pump 522, and a solenoid valve 523. The sealing pipe 521 passes through a through hole 11 and a pressure relief hole 423 in sequence and communicates with the chamber 45. The air pump 522 is sealed to the sealing pipe 521. The solenoid valve 523 is installed in the sealing pipe 521 and is used to control the entry and exit of gas. When the pressure sensor 51 detects that the air pressure in the chamber 45 is too high, the air pump 522 extracts the gas from the chamber 45 through the sealing pipe 521 to reduce the air pressure; when the air pressure is too low, the air pump 522 can inject gas into the chamber 45 to ensure stable air pressure. This allows the pressure relief mechanism 5 to monitor and adjust the air pressure in the chamber 45 through the pressure relief hole 423. This prevents the air in the chamber 45 from expanding due to heat and forming high pressure, which would affect the machining accuracy. By monitoring and adjusting the air pressure, the stability and accuracy of the spindle 41 operation can be guaranteed.

[0041] The electric spindle structure of this application embodiment is used for machining on a milling machine, see reference. Figure 2The milling machine includes a base, a machine body, a worktable, a feed system, a cooling and lubrication system, an electrical system, and the electric spindle structure described in Example 1. The base provides support and stability for the entire milling machine. The machine body connects the base to the electric spindle structure, and a lifting drive mechanism drives the electric spindle structure to rise and fall. When the electric spindle structure moves downward to the machining position, it begins machining. Guide rails are provided at the bottom of the worktable. The worktable is used to mount workpieces or fixtures, and workpiece feeding is achieved through longitudinal, transverse, and lifting movements. The feed system controls the worktable's movement in the longitudinal, transverse, and vertical directions to achieve feed motion. The cooling and lubrication system is sealed to the cooling tower channel 422, allowing coolant to continuously spray onto the cutting area after passing through the cooling channel 422, reducing temperature, minimizing tool wear, and flushing away chips. The electrical system controls parameters such as machine tool start-up, stop, spindle speed 41 rotation speed, and feed rate. The electric spindle structure enables the milling machine to maintain high precision and stability during machining, improving machining efficiency and product quality.

[0042] The implementation principle of this embodiment is as follows: By adding a pressure relief mechanism 5, the electric spindle structure of this embodiment can monitor and adjust the air pressure in the chamber 45 between the spindle 41 and the bushing 42 in real time, avoiding the impact on machining accuracy caused by high pressure due to the thermal expansion of air. Simultaneously, the tapered design of the spindle 41, the limiting setting of the ball bearing 43, and the setting of the cooling channel 422 all contribute to improving the rotational accuracy, stability, and service life of the spindle 41. In summary, the electric spindle structure of this application meets the requirements of advanced ceramic ultra-precision machining for the rotational stability, machining accuracy, speed, and sealing of the electric spindle. Compared with the prior art, the electric spindle structure of this embodiment solves the problems of reduced machining accuracy, significant vibration, and oil leakage that occur in existing electric spindle structures during long-term operation, improving the performance and reliability of the electric spindle structure. Example 2

[0043] The difference between this embodiment and the previous embodiment is that the transmission mechanism 3 uses a straight shaft structure instead of a gear system. The transmission mechanism 3 includes a straight shaft, with the output end of the drive mechanism 2 fixedly connected to one end of the straight shaft, and the other end fixedly connected to the main shaft 41. When the drive mechanism 2 starts, it drives the main shaft 41 to rotate coaxially via the straight shaft. Under the same driving conditions, belt drives have poor stability, with an output speed of only 3000-5000 RPM; gear drives have higher stability than belt drives, with an output speed of 10000-15000 RPM; and straight shaft drives have higher stability than gear drives, with the main shaft 41 rotating at a higher speed, reaching up to 20000 RPM.

[0044] 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 milling machine electric spindle structure for machining zirconia ceramic parts, comprising a housing (1) and a drive mechanism (2), a transmission mechanism (3), and a rotation mechanism (4) disposed in the housing (1), wherein the drive mechanism (2) drives the transmission mechanism (3) to rotate the rotation mechanism (4), characterized in that: It also includes a pressure relief mechanism (5). The rotating mechanism (4) includes a main shaft (41), a bushing (42), a ball bearing (43), and a sealing structure (44). The main shaft (41) is rotatably mounted on the housing (1) and fixedly connected to the output end of the transmission mechanism (3). The bushing (42) is sleeved on the outer wall of the main shaft (41). The outer wall of the bushing (42) is fixed inside the housing (1). At least one ball bearing (43) abuts against the inner wall of both ends of the bushing (42) and the outer wall of the main shaft (41). The main shaft (41) and the bushing A chamber (45) is formed between (42). A sealing structure (44) is provided between both ends of the bushing (42) and the main shaft (41) to seal the chamber (45). The bushing (42) is provided with a pressure relief hole (423) that communicates with the chamber (45). The housing (1) is provided with a through hole (11) at the position corresponding to the pressure relief hole (423). The pressure relief hole (423) and the through hole (11) are sealed and communicated with the pressure relief mechanism (5). The pressure relief mechanism (5) monitors and adjusts the air pressure of the chamber (45) through the pressure relief hole (423).

2. The milling machine electric spindle structure according to claim 1, characterized in that: The pressure relief mechanism (5) includes a pressure sensor (51) and a pressure regulating component (52). The pressure sensor (51) is disposed on the inner wall of the bushing (42) for monitoring the air pressure of the chamber (45). The pressure regulating component (52) adjusts the air pressure of the chamber (45) according to the air pressure data monitored by the pressure sensor (51).

3. The milling machine electric spindle structure according to claim 2, characterized in that: The air pressure regulating assembly (52) includes a sealing tube (521), an air pump (522), and a solenoid valve (523). The sealing tube (521) passes through the through hole (11) and the pressure relief hole (423) in sequence and communicates with the chamber (45). The air pump (522) is sealed to the sealing tube (521). The solenoid valve (523) is located in the sealing tube (521) and is used to control the entry and exit of gas.

4. The milling machine electric spindle structure according to claim 1, characterized in that: The outer wall of the spindle (41) is tapered, and the inner surface of the ball bearing (43) is tapered to match the outer wall of the spindle (41). The diameter of the spindle (41) gradually decreases from top to bottom.

5. The milling machine electric spindle structure according to claim 4, characterized in that, The taper of the spindle (41) is 1:20-1:

12.

6. The milling machine electric spindle structure according to claim 1, characterized in that, The bushing (42) has a limiting groove (421) on its inner wall. The ball bearing (43) is located in the limiting groove (421) and abuts against the groove wall to restrict the vertical movement of the limiting groove (421).

7. The milling machine electric spindle structure according to claim 1, characterized in that, The bushing (42) has a cooling channel (422) on its outer wall. The cooling channel (422) is connected to the cooling and lubrication system of the milling machine and is used to circulate coolant to the cooling channel (422). The pressure relief hole (423) is arranged to avoid the cooling channel (422).

8. The milling machine electric spindle structure according to claim 1, characterized in that, The sealing structure (44) includes a sleeve (441), a locking bolt (442), and a sealing ring (443). The sleeve (441) is fastened between the end of the sleeve shaft (42) and the main shaft (41) by the locking bolt (442). The sealing ring (443) is disposed between the sleeve (441) and the main shaft (41) to seal the chamber (45).

9. The milling machine electric spindle structure according to claim 1, characterized in that, The transmission mechanism (3) includes a first rotating shaft (31), a second rotating shaft (32), a first gear set (33), a second gear set (34), and a third gear set (35). The output end of the drive mechanism (2) is fixedly connected to the first rotating shaft (31). The first gear set (33) is coaxially fixed to the outer wall of the first rotating shaft (31). The second rotating shaft (32) is coaxially rotatably disposed on the chassis (1). The second gear set (34) is coaxially fixed to the outer wall of the second rotating shaft (32). The third gear set (35) is coaxially fixed to the outer wall of the main shaft (41). The first gear set (33), the second gear set (34), and the third gear set (35) mesh externally in sequence.

10. The milling machine electric spindle structure according to claim 1, characterized in that, The transmission mechanism is a straight shaft, one end of which is fixedly connected to the output end of the drive mechanism (2), and the other end is fixedly connected to the main shaft (41).

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