Active unloading hydrostatic spindle

Abstract

The application discloses an active unloading type liquid static pressure spindle and relates to the technical field of liquid static pressure spindles.The active unloading type liquid static pressure spindle comprises a spindle, a tray is fixedly arranged at the upper end of the spindle, a conical roller bearing is fixedly arranged at the lower part of the spindle, a radial bearing is fixedly arranged between the tray and the conical roller bearing on the spindle, an inner shell is sleeved outside the radial bearing and the conical roller bearing, a ring-shaped groove is oppositely formed in the middle of the upper and lower end faces of the inner shell, and an upper cover plate and a lower cover plate are respectively fixedly installed in the ring-shaped groove.The radial bearing limits the spindle in the radial direction, the conical roller bearing limits the spindle in the radial direction and the axial direction, the spindle is prevented from being displaced in the axial direction and the radial direction during operation, the transmission efficiency of the spindle and the stability of operation are improved, the machining precision of the machined objects on the tray is prevented from being affected, the appearance of defective products caused by precision is reduced, and the machining quality is improved.

Description

Technical Field

[0001] This invention relates to the field of hydrostatic spindle technology, specifically an active unloading hydrostatic spindle. Background Technology

[0002] Active unloading hydrostatic spindles are widely used in high-precision machining fields such as CNC machine tools, grinding equipment, and mirror polishing machines, and are of great significance for workpieces requiring high-speed and high-precision machining. During use and maintenance, it is essential to strictly follow operating procedures and regularly inspect and maintain the hydrostatic system to ensure the normal operation of the spindle and machining results. The main features of active unloading hydrostatic spindles include: hydrostatic support, active unloading design, high speed and high precision. During operation, the spindle can actively sense the machining load and automatically adjust the support pressure according to the load size, achieving active unloading of the machining load and ensuring stability and accuracy during machining. By applying hydrostatic pressure to the spindle support area, a liquid film support is formed, effectively reducing frictional resistance and vibration, and improving the rotor's rotational accuracy and stability.

[0003] The invention disclosed in authorization announcement number CN214290856U is an active unloading hydrostatic spindle. This utility model supports the work plate through several load adjustment cylinders set on the positioning plate. The bidirectional lubricated bearing connects the work plate and the load adjustment cylinders, making the connection more stable and the operation smoother. At the same time, the load adjustment cylinder and external sensor adjust the detection tube to detect the pressure in the cylinder at the lower end of the piston rod, so that the pressure in the cylinder at the lower end of the piston rod remains unchanged, thereby keeping the position of the work plate unchanged and improving its machining accuracy.

[0004] The above-mentioned device can achieve the purpose of active unloading, but the load adjustment cylinders are set separately, which makes it impossible for the multiple load adjustment cylinders to be adjusted in a coordinated manner, thus making it impossible to keep the working plate in a balanced state in time. At the same time, there is no circulating lubricating oil between the main shaft and the housing, which can effectively reduce frictional resistance and vibration, improve the rotational accuracy and stability of the rotor, and there is no oil film adjustment device, so it is impossible to adjust the oil film under different pressures. Summary of the Invention

[0005] The purpose of this invention is to provide an actively unloading hydrostatic spindle to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] An active unloading hydrostatic spindle includes a spindle, a tray fixedly mounted on the upper end of the spindle, a tapered roller bearing fixedly mounted on the lower part of the spindle, a radial bearing fixedly mounted on the spindle between the tray and the tapered roller bearing, an inner housing sleeved on the outer side of the radial bearing and the tapered roller bearing, and an annular grooves opposite each other on the middle of the upper and lower end faces of the inner housing, with an upper cover plate and a lower cover plate fixedly mounted in the annular grooves respectively;

[0008] An outer shell is fitted around the inner shell. A lubricating oil outlet is provided on the outer side of the radial bearing, which penetrates the outer shell and the inner shell. A lubricating oil inlet is provided on the outer side of the tapered roller bearing, which penetrates the outer shell and the inner shell. Several second limiting cavities are annularly formed inside the outer shell. Adjacent second limiting cavities are connected by annular oil passages. A slider is slidably arranged inside the second limiting cavity. A second piston is fixedly arranged on one side of the slider in the direction of the main shaft. A columnar groove is formed above the second limiting cavity inside the outer shell. A push rod is slidably arranged inside the columnar groove. The push rod is slidably connected to the slider. A pressure sensor is fixedly arranged at the upper end of the push rod.

[0009] As a further aspect of the present invention: A plurality of first limiting cavities are vertically formed within the outer shell, located inside the second limiting cavity. The first limiting cavities, the second limiting cavities, and the inner cavity of the inner shell are connected via oil passages. A plurality of arc-shaped plates are disposed between the radial bearing and the tapered roller bearing. A plurality of connecting rods are fixedly disposed on the outer wall of the arc-shaped plates. A hole is formed through the inner shell within the first limiting cavity of the outer shell. A connecting rod is slidably disposed within the hole. A first piston is fixedly disposed at the end of the connecting rod. The first piston is slidably disposed within the first limiting cavity, and the outer diameter of the first piston is the same as the inner diameter of the first limiting cavity. A hydraulic oil inlet is provided on the right side of the outer shell, connected to the first and second limiting cavities via oil passages. A hydraulic oil outlet is provided on the left side of the outer shell, connected to the first and second limiting cavities via oil passages.

[0010] As a further embodiment of the present invention: the inner diameter of the inner housing is the same as the outer diameter of the radial bearing and the tapered roller bearing, and the inner diameter of the radial bearing and the tapered roller bearing is the same as the outer diameter of the main shaft.

[0011] As a further embodiment of the present invention: a sealing groove is provided on the inner wall side of the annular groove, and a sealing ring is provided in the sealing groove.

[0012] As a further aspect of the present invention, the height of the lubricating oil outlet is higher than that of the lubricating oil inlet.

[0013] As a further embodiment of the present invention: the slope of the slider is 45°, and the lower end of the top rod is a 45° slope.

[0014] As a further embodiment of the present invention: the outer diameter of the second piston is the same as the inner diameter of the second limiting cavity.

[0015] As a further embodiment of the present invention: a sphere is rolled above the pressure sensor and the sphere is in close contact with the lower end face of the tray.

[0016] As a further embodiment of the present invention, the number of the arc-shaped plates is 6.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] 1. The radial bearing limits the spindle in the radial direction, allowing it to rotate smoothly. The tapered roller bearing limits the spindle in both the radial and axial directions, preventing displacement during operation and improving the spindle's transmission efficiency and operational stability. This also prevents the spindle from affecting the machining accuracy of the workpieces on the pallet, thereby reducing the occurrence of defective products due to inaccuracies and improving machining quality. At the same time, the inner housing, sealing ring, upper cover plate, and lower cover plate cooperate with each other to form a sealed space inside the inner housing, facilitating the temporary storage of lubricating oil and lubrication of the spindle, radial bearing, and tapered roller bearing. This effectively reduces frictional resistance and vibration between the bearings and the spindle, improving the spindle's rotational accuracy and stability.

[0019] 2. The sphere reduces friction between the push rod, pressure sensor, and tray, improving tray rotation stability. The pressure sensor detects the weight of objects on the tray in real time. Hydraulic oil applies pressure to the push rod via the slider, distributing the pressure exerted by the spindle on the tray and workpiece vertically. This keeps the tray and workpiece stable, improving processing stability. The 45° ramp on the slider ensures balanced forces in both horizontal and vertical directions, allowing hydraulic pressure to be transmitted to the push rod. This enables the pressure sensor to detect pressure stably, enhancing device stability.

[0020] 3. Hydraulic oil is supplied to the first and second limiting cavities through the hydraulic oil inlet, allowing the slider and the second piston to move appropriately within the second limiting cavity. This keeps the pressure sensor on the push rod in a stable state. Simultaneously, the hydraulic oil causes the first piston and connecting rod to move within the first limiting cavity, which in turn causes the arc plate to move between the main shaft and the inner housing. This allows the oil film between the arc plate and the main shaft to be adjusted to a suitable thickness, effectively reducing mechanical friction and main shaft wear. It also reduces energy loss from the main shaft and extends its service life, saving costs.

[0021] 4. The pressure sensor detects the pressure on the tray in real time. The pressure of the workpiece on the tray is transmitted to the slider through the tray, the ball, and the push rod. This causes the slider and the second piston to slide away from the push rod. The external hydraulic pump, combined with the real-time monitoring data from the pressure sensor, adjusts the hydraulic oil pressure delivered to the first and second limiting chambers. This keeps the pressure sensor reading constant, preventing vertical displacement of the tray and achieving stable processing of the workpiece on the tray. At the same time, the first piston and the connecting rod move inward under the pressure of the hydraulic oil, allowing the oil film between the several arc plates and the main shaft to be adjusted to a suitable thickness. Attached Figure Description

[0022] Figure 1 This is a three-dimensional structural diagram of an embodiment of the present invention.

[0023] Figure 2 This is a top view of the structure according to an embodiment of the present invention.

[0024] Figure 3 This is a schematic diagram of the main structure of an embodiment of the present invention.

[0025] Figure 4 This is a schematic cross-sectional view of section AA in an embodiment of the present invention.

[0026] Figure 5 This is a schematic cross-sectional view of the structure at BB in an embodiment of the present invention.

[0027] Figure 6 This is a partial exploded view of an embodiment of the present invention.

[0028] Figure 7 This is a partial three-dimensional structural diagram of the top rod in an embodiment of the present invention.

[0029] Figure 8 This is an exploded view of an embodiment of the present invention.

[0030] Figure reference numerals: 1. Outer shell; 2. Hydraulic oil inlet; 3. Hydraulic oil outlet; 4. Tray; 5. Lubricating oil inlet; 6. Lubricating oil outlet; 7. Main shaft; 8. Inner shell; 9. Arc plate; 91. First piston; 92. Connecting rod; 10. First limiting cavity; 11. Slider; 12. Second piston; 13. Second limiting cavity; 14. Push rod; 15. Pressure sensor; 16. Ball; 17. Upper cover plate; 18. Sealing ring; 19. Radial bearing; 20. Tapered roller bearing; 21. Lower cover plate; 22. Annular oil passage. Detailed Implementation

[0031] The following embodiments will describe the present invention in detail with reference to the accompanying drawings. In the drawings or description, similar or identical parts are referred to by the same reference numerals, and in practical applications, the shape, thickness, or height of each component may be enlarged or reduced. The embodiments listed in this invention are merely illustrative and not intended to limit the scope of the invention. Any obvious modifications or changes made to this invention do not depart from the spirit and scope of the invention.

[0032] Example

[0033] Please see Figures 1-8 In this embodiment of the invention, an active unloading hydrostatic spindle includes a spindle 7. A tray 4 is fixedly mounted on the upper end of the spindle 7, and a tapered roller bearing 20 is fixedly mounted on the lower part of the spindle 7. A radial bearing 19 is fixedly mounted on the spindle 7 between the tray 4 and the tapered roller bearing 20. An inner housing 8 is sleeved outside the radial bearing 19 and the tapered roller bearing 20. The inner diameter of the inner housing 8 is the same as the outer diameter of the radial bearing 19 and the tapered roller bearing 20, and the inner diameter of the radial bearing 19 and the tapered roller bearing 20 is the same as the outer diameter of the spindle 7. Annular grooves are formed opposite each other at the middle of the upper and lower end faces of the inner housing 8. Sealing grooves are formed opposite each other on the inner wall sides of the annular grooves. Sealing rings 18 are provided in the sealing grooves. An upper cover plate 17 and a lower cover plate 21 are fixedly mounted in the annular grooves, and the upper cover... Plate 17 and lower cover plate 21 fit tightly with sealing ring 18. The radial bearing 19 limits the spindle 7 in the radial direction, allowing the spindle 7 to rotate smoothly. The tapered roller bearing 20 limits the spindle 7 in both the radial and axial directions, preventing the spindle 7 from displacing in the axial and radial directions during operation. This improves the transmission efficiency and operational stability of the spindle 7, prevents it from affecting the machining accuracy of the workpiece on the tray 4, and reduces the occurrence of defective products due to inaccuracy, thus improving the machining quality. At the same time, the inner housing 8, sealing ring 18, upper cover plate 17 and lower cover plate 21 cooperate with each other to form a sealed space inside the inner housing 8, which facilitates the temporary storage of lubricating oil and lubrication of the spindle 7, radial bearing 19 and tapered roller bearing 20. This effectively reduces the frictional resistance and vibration between the bearings and the spindle 7, and improves the rotational accuracy and stability of the spindle 7.

[0034] An outer shell 1 is fitted around the outer side of the inner shell 8. A lubricating oil outlet 6 is provided on the outer side of the radial bearing 19, penetrating both the outer shell 1 and the inner shell 8. A lubricating oil inlet 5 is provided on the outer side of the tapered roller bearing 20, penetrating both the outer shell 1 and the inner shell 8. The lubricating oil outlet 6 is higher than the lubricating oil inlet 5. A plurality of second limiting cavities 13 are annularly formed inside the outer shell 1. Adjacent second limiting cavities 13 are connected by annular oil passages 22. A slider 11 is slidably disposed within each second limiting cavity 13. The slope of the slider 11 is 45°. A second piston 12 is fixedly disposed on one side of the slider 11 in the direction of the main shaft 7, and the outer diameter of the second piston 12 is the same as the inner diameter of the second limiting cavity 13. A columnar groove is formed above the second limiting cavity 13 inside the outer shell 1. A push rod 14 is slidably disposed within the columnar groove. The lower end of the push rod 14 has a 45° slope. The push rod 14 is slidably connected to the slider 11. Next, a pressure sensor 15 is fixedly installed at the upper end of the push rod 14. A ball 16 is rolled above the pressure sensor 15 and is in close contact with the lower end face of the tray 4. The ball 16 can reduce the friction between the push rod 14, the pressure sensor 15 and the tray 4, and improve the rotational stability of the tray 4. The pressure sensor 15 can detect the weight of the object on the tray 4 in real time. The hydraulic oil force is applied to the push rod 14 through the slider 11, which distributes the pressure applied by the spindle 7 to the tray 4 and the workpiece in the vertical direction, so that the tray 4 and the workpiece are always in a stable state, improving the stability of the workpiece processing. At the same time, the slope of the slider 11 is 45°, so that the force on the slider 11 in the horizontal and vertical directions is relatively balanced, allowing the pressure applied by the hydraulic oil to be transmitted to the push rod 14, so that the pressure sensor 15 can detect more stably and improve the stability of the device operation.

[0035] The outer shell 1 has several first limiting cavities 10 vertically formed inside the second limiting cavity 13. These first limiting cavities 10, the second limiting cavity 13, and the inner cavity of the inner shell 8 are connected by oil passages. Several arc-shaped plates 9 are positioned between the radial bearing 19 and the tapered roller bearing 20. Several connecting rods 92 are fixedly mounted on the outer wall of each arc-shaped plate 9. A hole is formed inside the first limiting cavity 10 of the outer shell 1, penetrating the inner shell 8. A connecting rod 92 is slidably mounted within this hole. A first piston 91 is fixedly mounted at the end of each connecting rod 92. The first piston 91 is slidably mounted within the first limiting cavity 10, and its outer diameter is the same as the inner diameter of the first limiting cavity 10. A hydraulic oil inlet 2 is located on the right side of the outer shell 1. The hydraulic oil inlet 2 is connected to the first limiting cavity 10 and the second limiting cavity 13 via oil passages. The outer casing 1 has a hydraulic oil outlet 3 on its left side. The hydraulic oil outlet 3 is connected to the first limiting cavity 10 and the second limiting cavity 13 through an oil passage. Hydraulic oil is supplied to the first limiting cavity 10 and the second limiting cavity 13 through the hydraulic oil inlet 2, allowing the slider 11 and the second piston 12 to move appropriately within the second limiting cavity 13, keeping the pressure sensor 15 on the push rod 14 in a stable state. At the same time, the hydraulic oil causes the first piston 91 and the connecting rod 92 to move within the first limiting cavity 10, thereby allowing the arc plate 9 to move between the main shaft 7 and the inner casing 8. This allows the oil film between the arc plate 9 and the main shaft 7 to be adjusted to a suitable thickness, effectively reducing mechanical friction and wear on the main shaft 7. It also reduces energy loss from the main shaft 7 and extends its service life, saving costs.

[0036] During operation, the inner housing 8, sealing ring 18, upper cover plate 17, and lower cover plate 21 cooperate to form a sealed space within the inner housing 8. Lubricating oil is supplied to the inner housing 8 through the lubricating oil inlet 5, filling it with lubricating oil. The lubricating oil is discharged to the outside through the lubricating oil outlet 6, allowing the lubricating oil to circulate within the inner housing 8. The workpiece is then placed on the tray 4, and the pressure sensor 15 monitors the pressure on the tray 4 in real time. The pressure of the workpiece on the tray 4 is transmitted to the slider 11 through the tray 4, ball 16, and push rod 14, causing the slider 11 and the second piston 12 to slide away from the push rod 14. The external hydraulic pump, combined with the real-time monitoring data from the pressure sensor 15, adjusts the hydraulic oil pressure supplied to the first limiting chamber 10 and the second limiting chamber 13, maintaining a constant value on the pressure sensor 15. The hydraulic system is designed to prevent vertical displacement of the pallet 4, ensuring stable processing of the workpiece on it. Simultaneously, under hydraulic pressure, the first piston 91 and connecting rod 92 move inwards towards the inner housing 8, allowing adjustment of the oil film between the arc plates 9 and the main shaft 7 to achieve a suitable thickness. After workpiece processing, the hydraulic oil delivery pressure is increased, causing the slider 11 and second piston 12 to return to their initial positions. The first piston 91 and connecting rod 92 are positioned inside the first limiting cavity 10, and hydraulic oil is discharged externally through the hydraulic oil outlet 3. At this point, the lubricating oil pressure inside the inner housing 8 is greater than the hydraulic oil pressure in the first limiting cavity 10 and the second limiting cavity 13, causing the first piston 91, connecting rod 92, and arc plates 9 to move away from the main shaft 7, thus resetting them and completing the workpiece processing.

[0037] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0038] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An active unloading type hydrostatic spindle, comprising a spindle (7), characterized in that, A tray (4) is fixedly installed at the upper end of the main shaft (7), and a tapered roller bearing (20) is fixedly installed at the lower part of the main shaft (7). A radial bearing (19) is fixedly installed between the tray (4) and the tapered roller bearing (20) on the main shaft (7). An inner housing (8) is sleeved on the outer side of the radial bearing (19) and the tapered roller bearing (20). An annular groove is opened in the middle of the upper and lower end faces of the inner housing (8). An upper cover plate (17) and a lower cover plate (21) are fixedly installed in the annular groove respectively. The outer shell (1) is fitted around the inner shell (8). The radial bearing (19) has a lubricating oil outlet (6) through the outer shell (1) and the inner shell (8). The tapered roller bearing (20) has a lubricating oil inlet (5) through the outer shell (1) and the inner shell (8). The outer shell (1) has several second limiting cavities (13) in a ring shape. Adjacent second limiting cavities (13) are connected by an annular oil passage (22). A slider (11) is slidably arranged in the second limiting cavity (13). A second piston (12) is fixedly arranged on one side of the slider (11) in the direction of the main shaft (7). A columnar groove is opened above the second limiting cavity (13) in the outer shell (1). A push rod (14) is slidably arranged in the columnar groove. The push rod (14) is slidably connected to the slider (11). A pressure sensor (15) is fixedly arranged at the upper end of the push rod (14). The outer shell (1) has several first limiting cavities (10) vertically formed inside the second limiting cavity (13). The first limiting cavities (10), the second limiting cavity (13), and the inner cavity of the inner shell (8) are connected by oil passages. Several arc-shaped plates (9) are provided between the radial bearing (19) and the tapered roller bearing (20). Several connecting rods (92) are fixedly arranged on the outer wall of the arc-shaped plates (9). A hole is formed inside the first limiting cavity (10) of the outer shell (1) penetrating the inner shell (8). A connecting rod (92) is slidably arranged in the hole. A first piston (91) is fixedly provided at the end of the connecting rod (92). The first piston (91) is slidably provided in the first limiting cavity (10) and the outer diameter of the first piston (91) is the same as the inner diameter of the first limiting cavity (10). A hydraulic oil inlet (2) is provided on the right side of the outer shell (1). The hydraulic oil inlet (2) is connected to the first limiting cavity (10) and the second limiting cavity (13) through an oil passage. A hydraulic oil outlet (3) is provided on the left side of the outer shell (1). The hydraulic oil outlet (3) is connected to the first limiting cavity (10) and the second limiting cavity (13) through an oil passage. The slope of the slider (11) is 45°, and the lower end of the top rod (14) is a 45° slope; A ball (16) is rolled above the pressure sensor (15) and the ball (16) is in close contact with the lower end face of the tray (4).

2. The active unloading hydrostatic spindle according to claim 1, characterized in that, The inner diameter of the inner housing (8) is the same as the outer diameter of the radial bearing (19) and the tapered roller bearing (20), and the inner diameter of the radial bearing (19) and the tapered roller bearing (20) is the same as the outer diameter of the main shaft (7).

3. The active unloading hydrostatic spindle according to claim 1, characterized in that, A sealing groove is provided on the inner wall of the annular groove, and a sealing ring (18) is provided in the sealing groove.

4. The active unloading hydrostatic spindle according to claim 3, characterized in that, The height of the lubricating oil outlet (6) is higher than that of the lubricating oil inlet (5).

5. The active unloading hydrostatic spindle according to claim 1, characterized in that, The outer diameter of the second piston (12) is the same as the inner diameter of the second limiting cavity (13).

6. The actively unloading hydrostatic spindle according to claim 1, characterized in that, The number of the arc-shaped plates (9) is 6.

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