Magnetic and aerostatic hybrid support motorized spindle

Abstract

A kind of magnetic gas hybrid support electric spindle belongs to electric spindle system technical field.The present application includes rotor assembly,thrust disc is arranged on the rotor assembly, dynamic pressure gas bearing is arranged outside the rotor assembly, electromagnetic bearing assembly is arranged in the dynamic pressure gas bearing, the thrust disc is located in the electromagnetic bearing assembly, the two sides of the dynamic pressure gas bearing are respectively connected with the same structure permanent magnet bearing assembly, wherein one permanent magnet bearing assembly outer end is connected with driving motor, the driving motor is connected with one end of the rotor assembly to drive the rotation of the rotor assembly.The present application can realize stable suspension when working, solve the problem of dry friction existing in gas bearing start-stop phase.

Description

Technical Field

[0001] This invention belongs to the technical field of electric spindle systems, and specifically relates to a magnetic-pneumatic hybrid-supported electric spindle. Background Technology

[0002] With the emergence of more and more new integrated circuits, integrated circuits are developing towards lightweighting and miniaturization, which requires increasingly higher complexity and precision of chips on wafers. Wafer dicing is the final process in wafer fabrication, determining the final chip yield, making it a highly overlapping process. Dicing utilizes a high-speed rotating spindle of a wafer dicing machine to drive ultra-thin grinding wheels, using powerful grinding to separate the wafer material into individual chips. The performance of the electric spindle is a crucial factor determining the dicing quality and precision, and wafer dicing requires the electric spindle to achieve high-quality dicing under various operating conditions.

[0003] Dynamic pressure air bearings offer advantages such as high precision, long lifespan, and high maximum speed, making them suitable for wafer dicing. However, dynamic pressure air bearings experience dry friction during start-up and shutdown, resulting in significant spindle vibration that greatly affects dicing quality. Meanwhile, magnetic bearings offer advantages such as contactless operation, wear-free operation, no lubrication required, and high speed, making them widely used in electric spindles. Therefore, designing an electric spindle with a hybrid support system combining magnetic and dynamic pressure air bearings is crucial to address the dry friction issue during start-up and shutdown. Summary of the Invention

[0004] This invention addresses the aforementioned problems and overcomes the shortcomings of existing technologies by providing a magnetic-pneumatic hybrid-supported electric spindle. This invention enables stable levitation during operation and solves the problem of dry friction during the start-up and shutdown phases of air bearings.

[0005] To achieve the above objectives, the present invention adopts the following technical solution.

[0006] This invention provides a magnetic-pneumatic hybrid-supported electric spindle, characterized in that it includes a rotor assembly, a thrust disk disposed on the rotor assembly, a dynamic pressure air bearing disposed outside the rotor assembly, an electromagnetic bearing assembly disposed inside the dynamic pressure air bearing, the thrust disk being located inside the electromagnetic bearing assembly, and permanent magnet bearing assemblies with identical structures connected to both sides of the dynamic pressure air bearing, one of the permanent magnet bearing assemblies having its outer end connected to a drive motor, and the drive motor being connected to one end of the rotor assembly to drive the rotor assembly to rotate.

[0007] Furthermore, the dynamic pressure air bearing includes a first dynamic pressure air bearing stator and a second dynamic pressure air bearing stator that cooperate with each other. The first dynamic pressure air bearing stator and the second dynamic pressure air bearing stator are respectively connected to two permanent magnet bearing assemblies, and the electromagnetic bearing assembly is sandwiched between the first dynamic pressure air bearing stator and the second dynamic pressure air bearing stator.

[0008] Furthermore, the electromagnetic bearing assembly includes a coil, a magnetically conductive stator, and a non-magnetically conductive sleeve. The non-magnetically conductive sleeve is sandwiched between the first dynamic pressure air bearing stator and the second dynamic pressure air bearing stator. The magnetically conductive stator is fixed on the non-magnetically conductive sleeve, and the coil is disposed inside the magnetically conductive stator.

[0009] Furthermore, the permanent magnet bearing assembly includes a permanent magnet bearing housing, an eccentric stator magnetic ring, a rotor magnetic ring, an eccentric sleeve, and a clamping element. The permanent magnet bearing housing is connected to the dynamic pressure air bearing. The eccentric sleeve is disposed inside the permanent magnet bearing housing. The eccentric stator magnetic ring is assembled inside the eccentric sleeve and fixed inside the eccentric sleeve by the clamping element. The rotor magnetic ring is fixed on the rotor assembly and interacts with the eccentric stator magnetic ring.

[0010] Furthermore, both the eccentric stator magnetic ring and the rotor magnetic ring are axially magnetized, and the inner cylindrical surface of the eccentric stator magnetic ring is offset upwards by a certain distance in the radial position relative to the outer cylindrical surface.

[0011] Furthermore, the inner cylindrical surface of the eccentric sleeve is offset downward in the radial direction relative to the outer cylindrical surface by a certain distance, in order to mate with the eccentric stator magnetic ring.

[0012] Furthermore, the rotor magnetic ring is offset by a certain distance relative to the eccentric stator magnetic ring towards the axial center of the rotor assembly.

[0013] Furthermore, the permanent magnet bearing assembly also includes an adjusting shim, which is arranged between the eccentric sleeve and the eccentric stator magnetic ring.

[0014] Furthermore, a cover is connected to the outer end of the permanent magnet bearing assembly on the side opposite to the drive motor, and the other end of the rotor assembly passes through the cover.

[0015] Furthermore, the motor rotor of the drive motor is connected to the rotor assembly.

[0016] The beneficial effects of the present invention.

[0017] The present invention relates to a magnetically-supported hybrid electric spindle. Through the design of the spindle support method, a magnetically-supported hybrid electric spindle is achieved. The hydrodynamic air bearing provides primary support at high spindle speeds, and its load-bearing capacity increases with the rotational speed. However, dry friction exists during start-up and shutdown, and the resulting vibration affects cutting quality. Therefore, a permanent magnet bearing assembly is arranged. This assembly mainly consists of an eccentric stator magnetic ring and a rotor magnetic ring, and is axially magnetized, generating radial repulsive force. This eccentric stator magnetic ring increases the radial force provided by the permanent magnet bearing, preventing the rotor assembly from failing to levitate when static due to excessive rotor mass. Furthermore, an eccentric sleeve is arranged to cooperate with the eccentric stator magnetic ring to facilitate the overall assembly and fit of the electric spindle.

[0018] This invention allows adjustment of the distance between the eccentric stator magnetic ring and the rotor magnetic ring by adjusting shims. Different distances result in different radial forces between the permanent magnet bearings; the closer the distance, the greater the radial force, and the farther the distance, the smaller the radial force. This allows for stable levitation of the rotor assembly by adjusting this distance when the rotor assembly mass changes. The permanent magnet bearings on both sides also generate axial forces, which cancel each other out, significantly reducing the power consumption of the electromagnetic bearings in the axial direction. This also allows for a reduction in the size of the electromagnetic bearings, resulting in a smaller and more compact overall magnetic-pneumatic hybrid-supported electric spindle.

[0019] When the drive motor is working, the rotor, under the action of the permanent magnet bearing, achieves contactless and frictionless operation between the rotor and the stator. As the speed continuously increases, the load-bearing capacity of the hydrodynamic air bearing continuously increases, enabling this magnetic-pneumatic hybrid supported electric spindle to operate over a wide speed range. When this magnetic-pneumatic hybrid supported electric spindle is subjected to axial load, the electromagnetic bearing adjusts the control current to regulate the axial force of the electromagnetic bearing assembly on the thrust plate on the rotor assembly, achieving stable levitation of the five degrees of freedom of this magnetic-pneumatic hybrid supported electric spindle, and still achieving high-quality cutting under different working conditions. Attached Figure Description

[0020] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0021] Figure 1 This is a schematic diagram of the overall external structure of the present invention.

[0022] Figure 2 This is a side cross-sectional structural diagram of the present invention.

[0023] Figure 3 This is an exploded structural diagram of the electromagnetic bearing assembly of the present invention.

[0024] Figure 4 This is an exploded structural diagram of the permanent magnet bearing assembly of the present invention.

[0025] Figure 5 This is a cross-sectional schematic diagram of the eccentric stator magnetic ring and rotor magnetic ring of the permanent magnet bearing assembly of the present invention.

[0026] Figure 6 This is a schematic diagram of the magnetization principle of the permanent magnet bearing assembly of the present invention.

[0027] The markings in the diagram are as follows: 1 is the rotor assembly, 2 is the thrust disc, 3 is the first dynamic pressure air bearing stator, 4 is the second dynamic pressure air bearing stator, 5 is the coil, 6 is the magnetically conductive stator, 7 is the non-magnetically conductive sleeve, 8 is the permanent magnet bearing assembly, 9 is the permanent magnet bearing housing, 10 is the eccentric stator magnetic ring, 11 is the rotor magnetic ring, 12 is the eccentric sleeve, 13 is the clamping element, 14 is the adjusting shim, 15 is the drive motor, 16 is the cover, 17 is the motor rotor, and 18 is the motor stator. Detailed Implementation

[0028] Combined with appendix Figure 1-2 As shown, this embodiment provides a magnetic-pneumatic hybrid-supported electric spindle, including a rotor assembly 1, a thrust disk 2 disposed on the rotor assembly 1, a dynamic pressure air bearing disposed outside the rotor assembly 1, and an electromagnetic bearing assembly disposed inside the dynamic pressure air bearing. The dynamic pressure air bearing includes a first dynamic pressure air bearing stator 3 and a second dynamic pressure air bearing stator 4 that cooperate with each other. The first dynamic pressure air bearing stator 3 and the second dynamic pressure air bearing stator 4 are respectively connected to two permanent magnet bearing assemblies 8. The electromagnetic bearing assembly is sandwiched in the middle by the first dynamic pressure air bearing stator 3 and the second dynamic pressure air bearing stator 4, and the thrust disk 2 is located inside the electromagnetic bearing assembly.

[0029] The two sides of the dynamic pressure air bearing are respectively connected to permanent magnet bearing assemblies 8 with the same structure. The outer end of one of the permanent magnet bearing assemblies 8 is connected to the drive motor 15. The drive motor 15 has a motor stator 18 and a motor rotor 17 that cooperate with each other. The motor rotor 17 of the drive motor 15 is connected to one end of the rotor assembly 1, and the rotor assembly 1 is driven to rotate by the drive motor 15.

[0030] The radial load is mainly provided by the dynamic pressure air bearing, and the load-bearing capacity of the dynamic pressure air bearing increases with the speed of the drive motor 15. However, during the start-up and shutdown phases, the speed is low, and the low load-bearing capacity of the dynamic pressure air bearing causes the rotor assembly 1 to be in a dry friction stage, resulting in greater vibration. The permanent magnet bearing assembly 8 is required to provide a certain radial support force at low speeds to avoid the dry friction stage of the electric spindle during start-up and shutdown. The axial position of the electric spindle is controlled by the electromagnetic bearing assembly, ultimately achieving stable five-degree-of-freedom suspension of the entire electric spindle.

[0031] Combined with appendix Figure 3As shown, the electromagnetic bearing assembly includes a coil 5, a magnetically conductive stator 6, and a non-magnetically conductive sleeve 7. The non-magnetically conductive sleeve 7 is sandwiched between the first dynamic pressure air bearing stator 3 and the second dynamic pressure air bearing stator 4. The magnetically conductive stator 6 is fixed on the non-magnetically conductive sleeve 7, and the coil 5 is disposed inside the magnetically conductive stator 6.

[0032] When coil 5 is energized, the magnetic flux it generates flows along the magnetically conductive stator 6, the thrust disk 2, and the gap between them, generating an attractive force on the thrust disk 2, thereby restricting the axial position of the entire rotor assembly 1. The attractive force can be controlled by actively controlling the magnitude of the current in coil 5, thus controlling the axial position of the electric spindle in real time.

[0033] Combined with appendix Figure 4-6 As shown, the permanent magnet bearing assembly 8 includes a permanent magnet bearing housing 9, an eccentric stator magnetic ring 10, a rotor magnetic ring 11, an eccentric sleeve 12, and a clamping element 13. The permanent magnet bearing housing 9 is connected to the dynamic pressure air bearing. The eccentric sleeve 12 is disposed inside the permanent magnet bearing housing 9. The eccentric stator magnetic ring 10 is assembled inside the eccentric sleeve 12, and the eccentric stator magnetic ring 10 is fixed inside the eccentric sleeve 12 by the clamping element 13 to prevent axial movement of the eccentric stator magnetic ring 10.

[0034] The inner cylindrical surface of the eccentric sleeve 12 is offset downward by a certain distance in the radial position relative to the outer cylindrical surface, so as to cooperate with the eccentric stator magnetic ring 10 for assembly.

[0035] Both the eccentric stator magnetic ring 10 and the rotor magnetic ring 11 are axially magnetized, repelling each other radially and generating a radial force. The inner cylindrical surface of the eccentric stator magnetic ring 10 is radially offset upwards relative to its outer cylindrical surface by a certain distance. Due to the large mass of the rotor assembly 1 and the small clearance of the hydrodynamic air bearing, the permanent magnet bearing assembly 8 cannot provide sufficient radial force to levitate the rotor assembly 1. Therefore, when the inner cylindrical surface of the eccentric stator magnetic ring 10 is radially offset upwards relative to its outer cylindrical surface by a certain distance, the radial force provided by the permanent magnet bearing assembly 8 increases to a level sufficient to counteract the rotor mass.

[0036] The rotor magnetic ring 11 is offset by a certain distance relative to the eccentric stator magnetic ring 10 towards the axial center of the rotor assembly 1. The rotor magnetic ring 11 is fixed on the rotor assembly 1 and interacts with the eccentric stator magnetic ring 10.

[0037] Because the eccentric stator magnetic ring 10 and rotor magnetic ring 11 are axially magnetized, a large axial force is generated between them. This necessitates increasing the axial force of the electromagnetic bearing assembly, thus increasing its size and power consumption. Therefore, by offsetting the rotor magnetic ring 11 relative to the eccentric stator magnetic ring 10 towards the axial center of the rotor assembly 1, the permanent magnet bearing assemblies on both sides generate axial forces towards the center of the rotor assembly 1 in opposite directions, effectively canceling each other out. This significantly reduces the power consumption of the electromagnetic bearing assembly, decreases its required size, and makes the entire magnetic hybrid support electric spindle structure more compact.

[0038] The permanent magnet bearing assembly 8 also includes an adjusting shim 14, which is arranged between the eccentric sleeve 12 and the eccentric stator magnetic ring 10 to adjust the axial position of the eccentric stator magnetic ring 10.

[0039] When the axial spacing between the eccentric stator magnetic ring 10 and the rotor magnetic ring 11 is different, the radial force of the permanent magnet bearing assembly 8 is also different. Therefore, the radial force of the permanent magnet bearing assembly 8 can be changed by appropriately increasing or decreasing the adjusting shims 14. The radial force of the permanent magnet bearing assembly 8 can be adjusted in real time according to the mass of the rotor assembly 1 so that the rotor assembly 1 can be stably suspended.

[0040] Since dust and impurities are generated during the operation of the electric spindle, a cover 16 is connected to the outer end of the permanent magnet bearing assembly 8 on the side opposite to the drive motor 15. The other end of the rotor assembly 1 passes through the cover 16 to block dust and impurities.

[0041] The method of using this invention is as follows:

[0042] The rotor assembly 1 is rotated by the drive motor 15. At low speeds, the permanent magnet bearing assembly 8 provides the load-bearing capacity to suspend the rotor assembly 1. As the speed increases, the load-bearing capacity gradually increases with the dynamic pressure air bearing, and the rotor assembly 1 is suspended by the viscous gas in the gap between the dynamic pressure air bearing. When the electric spindle is subjected to axial load, the current of the control coil 5 generates an electromagnetic attraction force between the magnetic stator 6 and the thrust disk 2, controlling the axial position of the rotor assembly 1, and ultimately achieving stable five-degree-of-freedom suspension of the magnetically-pneumatically-supported electric spindle.

[0043] It is understood that the above specific description of the present invention is only for illustrating the present invention and is not limited to the technical solutions described in the embodiments of the present invention. Those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention to achieve the same technical effect; as long as the use needs are met, they are all within the protection scope of the present invention.

Claims

1. A magnetic-pneumatic hybrid supported electric spindle, characterized in that, The rotor assembly (1) includes a thrust disk (2) on the rotor assembly (1), a dynamic pressure air bearing on the outside of the rotor assembly (1), an electromagnetic bearing assembly inside the dynamic pressure air bearing, the thrust disk (2) being located inside the electromagnetic bearing assembly, and permanent magnet bearing assemblies (8) with the same structure connected to both sides of the dynamic pressure air bearing, one of the permanent magnet bearing assemblies (8) having its outer end connected to a drive motor (15), and the drive motor (15) being connected to one end of the rotor assembly (1) to drive the rotor assembly (1) to rotate; The permanent magnet bearing assembly (8) includes a permanent magnet bearing housing (9), an eccentric stator magnetic ring (10), a rotor magnetic ring (11), an eccentric sleeve (12), and a clamping element (13). The permanent magnet bearing housing (9) is connected to the dynamic pressure air bearing. The eccentric sleeve (12) is disposed inside the permanent magnet bearing housing (9). The eccentric stator magnetic ring (10) is assembled inside the eccentric sleeve (12) and the eccentric stator magnetic ring (10) is fixed inside the eccentric sleeve (12) by the clamping element (13). The rotor magnetic ring (11) is fixed on the rotor assembly (1) and interacts with the eccentric stator magnetic ring (10). Both the eccentric stator magnetic ring (10) and the rotor magnetic ring (11) are axially magnetized, and the inner cylindrical surface of the eccentric stator magnetic ring (10) is offset upward by a certain distance in the radial position relative to the outer cylindrical surface. The rotor magnetic ring (11) is offset by a certain distance relative to the eccentric stator magnetic ring (10) towards the axial center position of the rotor assembly (1); The dynamic pressure air bearing includes a first dynamic pressure air bearing stator (3) and a second dynamic pressure air bearing stator (4) that cooperate with each other. The first dynamic pressure air bearing stator (3) and the second dynamic pressure air bearing stator (4) are respectively connected to two permanent magnet bearing assemblies (8). The electromagnetic bearing assembly is sandwiched between the first dynamic pressure air bearing stator (3) and the second dynamic pressure air bearing stator (4).

2. The magnetic-pneumatic hybrid supported electric spindle according to claim 1, characterized in that, The electromagnetic bearing assembly includes a coil (5), a magnetic stator (6), and a non-magnetic sleeve (7). The non-magnetic sleeve (7) is sandwiched between the first dynamic pressure air bearing stator (3) and the second dynamic pressure air bearing stator (4). The magnetic stator (6) is fixed on the non-magnetic sleeve (7), and the coil (5) is disposed inside the magnetic stator (6).

3. The magnetic-pneumatic hybrid supported electric spindle according to claim 1, characterized in that, The inner cylindrical surface of the eccentric sleeve (12) is offset downward by a certain distance in the radial position relative to the outer cylindrical surface, so as to cooperate with the eccentric stator magnetic ring (10) for assembly.

4. The magnetic-pneumatic hybrid supported electric spindle according to claim 1, characterized in that, The permanent magnet bearing assembly (8) also includes an adjusting shim (14) arranged between the eccentric sleeve (12) and the eccentric stator magnetic ring (10).

5. A magnetic-pneumatic hybrid supported electric spindle according to claim 1, characterized in that, A cover (16) is connected to the outer end of the permanent magnet bearing assembly (8) on the side opposite to the drive motor (15), and the other end of the rotor assembly (1) passes through the cover (16).

6. A magnetic-pneumatic hybrid supported electric spindle according to claim 1, characterized in that, The motor rotor (17) of the drive motor (15) is connected to the rotor assembly (1).

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