Power-off protection device, spindle system and thinning machine

Abstract

The present application provides a power-off protection device, a spindle system, and a thinning machine, which relate to the technical field of semiconductor processing equipment and include a first power-off protection unit, which includes: a mating portion fixedly mounted on the spindle; a receiving portion coaxially sleeved on the outer periphery of the mating portion and located below the mating portion, capable of forming a friction pair with the mating portion, realizing torque transmission with the mating portion when engaged, and providing an upward support force to the mating portion and the spindle; a first sliding portion coaxially sleeved on the outer periphery of the receiving portion, forming a rotation pair with the receiving portion and forming an axial linkage fit; a biasing member acting on the first sliding portion and applying an upward biasing force to the first sliding portion in the axial direction, so that the receiving portion and the mating portion form a coupled state; a pressurizing mechanism, which generates a force in the opposite direction to the biasing force in the power-on state, and the force is greater than the biasing force, so as to release the coupled state; and the force is eliminated in the power-off state. The problem of using a non-contact bearing for reliable power-off protection is solved.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor processing equipment, and in particular to a power-off protection device, a spindle system, and a thinning machine. Background Art

[0002] Thinning machines are key equipment in semiconductor manufacturing, primarily used for wafer backside thinning. As semiconductor devices evolve toward miniaturization and higher integration, wafer thickness directly impacts chip packaging density, heat dissipation, and mechanical strength. Thinning machines use techniques such as mechanical grinding, chemical mechanical polishing, or plasma etching to reduce wafer thickness from hundreds of microns to tens or even just a few microns to meet the demands of advanced packaging.

[0003] Traditional thinning machines typically utilize a mechanical bearing support structure, consisting of a spindle and a grinding disc. The grinding disc is fixed to the base of the spindle, and a drive mechanism drives the spindle to rotate, thereby grinding and polishing the wafer. To improve spindle stability, a mechanical bearing support structure is often used around the spindle's periphery to restrict the spindle's non-axial degrees of freedom, retaining only rotational freedom around the axis.

[0004] However, the mechanical bearing structure has inherent defects: friction loss: the friction generated between the mechanical components during operation will cause the spindle to heat up; vibration problem: the vibration caused by friction will reduce the stability of the spindle rotation; reduced processing accuracy: the combined effect of the above factors will directly affect the process accuracy of wafer thinning.

[0005] To overcome the inherent shortcomings of mechanical bearings, current mainstream technologies utilize non-contact bearing solutions. Examples include magnetic bearings, which utilize electromagnetic fields to suspend the spindle; hydrostatic bearings, which utilize a high-pressure oil film to support the spindle; and pneumatic bearings, which rely on compressed air to form an air suspension layer. By eliminating mechanical contact, these technologies significantly reduce friction loss and vibration amplitude, significantly improving spindle operational stability.

[0006] While non-contact bearings offer significant advantages, they rely on electrical energy to maintain a stable magnetic field, hydraulic pressure, or air pressure. Once a power outage occurs, the electromagnetic field of a magnetic bearing, the hydraulic pressure of a hydrostatic bearing, or the air pressure of a pneumatic bearing will instantly disappear. The spindle, without support, will mechanically collide with surrounding components, potentially causing permanent damage to the spindle structure and the loss of the wafer being processed. Summary of the Invention

[0007] The purpose of this application is to provide a power-off protection device, a spindle system and a thinning machine, aiming to solve the problem of how to provide support for the spindle in the event of a power outage when using a non-contact bearing.

[0008] Additional aspects and advantages of the present application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the present application.

[0009] According to a first aspect of the present application, a power failure protection device is provided, comprising: a first power failure protection unit, wherein the first power failure protection unit comprises:

[0010] The matching portion is fixed on the main shaft;

[0011] a receiving portion, coaxially sleeved on the outer periphery of the mating portion and located below the mating portion, capable of forming a friction pair with the mating portion, realizing torque transmission with the mating portion when engaged, and providing an upward supporting force for the mating portion and the main shaft;

[0012] A first sliding portion is coaxially sleeved on the outer periphery of the receiving portion, forming a rotation pair with the receiving portion and forming an axial linkage fit;

[0013] a biasing member acting on the first sliding portion and applying an upward biasing force to the first sliding portion in the axial direction to drive the first sliding portion to move toward the matching portion, so that the receiving portion and the matching portion are in a coupled state;

[0014] The pressurizing mechanism generates a force opposite to the biasing force in a power-on state, and the force is greater than the biasing force, so as to release the combined state; and the force is eliminated in a power-off state.

[0015] In an exemplary embodiment of the present application, a mechanical bearing is further included, which is surrounded between the receiving portion and the first sliding portion; the inner ring of the mechanical bearing is relatively fixed to the receiving portion, and the outer ring of the mechanical bearing is relatively fixed to the first sliding portion.

[0016] In an exemplary embodiment of the present application, the number of the mechanical bearings is two, and the two mechanical bearings are paired angular contact ball bearings and are provided with a preload force.

[0017] In an exemplary embodiment of the present application, the mating portion is configured as an outer cone inner sleeve, and the bottom of the outer cone inner sleeve has a conical surface that is closed from top to bottom along the axial direction; the receiving portion is configured as an inner cone outer sleeve, and the top of the inner cone outer sleeve has a coupling surface that is closed from top to bottom along the axial direction, and the coupling surface matches the conical surface to constitute a disengageable conical friction pair.

[0018] In an exemplary embodiment of the present application, the pressurizing mechanism includes:

[0019] an inner magnetic core fixedly disposed on the outer periphery of the first sliding portion;

[0020] The outer magnetic core surrounds the outer side of the inner magnetic core, and a radial gap is formed between the outer magnetic core and the inner magnetic core. When the outer magnetic core is energized, it can generate a magnetic pole reaction with the inner magnetic core, and drive the first sliding part and the receiving part to overcome the biasing force and move away from the matching part along the axial direction of the main shaft, so that the receiving part is separated from the matching part.

[0021] In an exemplary embodiment of the present application, the first power-off protection unit further includes: a bearing inner cover and a bearing outer cover, the bearing inner cover is fixedly connected to one end of the receiving part, the bearing outer cover is fixedly connected to one end of the first sliding part, the bearing inner cover and the bearing outer cover constitute a labyrinth seal at one end of the first power-off protection unit, and the end portion of the other end of the receiving part and the end portion of the other end of the first sliding part constitute a labyrinth seal at the other end of the first power-off protection unit.

[0022] In an exemplary embodiment of the present application, a second power-off protection unit having the same structure as the first power-off protection unit is further included, and the structures of the first power-off protection unit and the second power-off protection unit are mirror-imaged along the radial direction of the main axis.

[0023] According to a second aspect of the present application, a spindle system is provided, comprising the power-off protection device and a spindle as described in any one of the above items.

[0024] In an exemplary embodiment of the present application, it further includes:

[0025] The radial bearing unit includes a first magnetic fitting and a second magnetic fitting, wherein the first magnetic fitting is fixedly sleeved on the circumferential outer side of the main shaft; the second magnetic fitting surrounds the outer side of the first magnetic fitting and forms a uniform radial gap with the first magnetic fitting, and the magnetic forces of the first and second magnetic fittings in all directions around the main shaft are equal;

[0026] The axial bearing unit includes an upper magnetic fitting, a lower magnetic fitting and an intermediate magnetic fitting. The upper magnetic fitting, the lower magnetic fitting and the intermediate magnetic fitting are all coaxially sleeved on the circumference of the main shaft. The intermediate magnetic fitting is relatively fixed to the main shaft and is located between the upper magnetic fitting and the lower magnetic fitting; axial gaps are formed between the upper magnetic fitting and the intermediate magnetic fitting, and between the lower magnetic fitting and the intermediate magnetic fitting, respectively.

[0027] According to a third aspect of the present application, a thinning machine is provided, comprising any one of the spindle systems described above.

[0028] The exemplary embodiments of the present application may have some or all of the following beneficial effects:

[0029] In a power-off protection device provided in an exemplary embodiment of the present application, when powered on, the non-contact bearings can restrict the radial and axial degrees of freedom of the spindle, allowing it to rotate only around its own axis. During spindle rotation, the power-off protection unit does not restrict the spindle, thereby ensuring contact-free rotation. When a power outage occurs, the first power-off protection unit immediately intervenes, restricting the spindle so that it continues to rotate around its own axis and providing good support. Specifically, when powered on, the pressure mechanism applies a downward force to the first sliding portion, causing it to move the receiving portion away from the mating portion, thereby ensuring the spindle's suspension. At this point, the biasing member is in an energy-storing state. When power is lost, the pressure from the pressure mechanism on the first sliding portion is removed, releasing the stored biasing force in the biasing member. This causes the first sliding portion to instantly move the receiving portion toward the mating portion, placing the mating portion and the receiving portion in contact. Under inertia, the spindle drives the mating portion to continue rotating, while the mating portion, in turn, rotates along with the receiving portion through friction with the receiving portion. The receiving portion and the first sliding portion rotate relative to each other. In summary, when powered on, the first power-off protection unit does not restrict the spindle, maintaining its suspension and ensuring its stability during operation. When power is lost, the power-off protection unit instantly intervenes and restricts the spindle, providing good support for the spindle and preventing it from colliding with other machinery, thereby protecting the spindle and the wafer being processed.

[0030] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings are incorporated into and constitute a part of the specification, illustrate embodiments consistent with the present application, and together with the specification, are used to explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0032] Figure 1 A schematic diagram of a spindle system according to an embodiment of the present application is shown;

[0033] Figure 2 A three-dimensional cross-sectional schematic diagram of the spindle system in an embodiment of the present application is shown;

[0034] Figure 3 A schematic cross-sectional view of the main shaft system in an embodiment of the present application is shown;

[0035] Figure 4 for Figure 3A partial enlarged schematic diagram of part A;

[0036] Figure 5 for Figure 3 A partial enlarged schematic diagram of part B;

[0037] Figure 6 for Figure 3 A partial enlarged schematic diagram of part C in the middle;

[0038] Figure 7 for Figure 3 A partial enlarged schematic diagram of part D in the middle;

[0039] Figure 8 for Figure 3 A partial enlarged schematic diagram of part E in the middle;

[0040] Figure 9 for Figure 3 A partial enlarged schematic diagram of part F in the middle;

[0041] Figure 10 for Figure 3 A partial enlarged schematic diagram of part I;

[0042] Figure 11 A three-dimensional cross-sectional schematic diagram of a radial bearing unit 1 in an embodiment of the present application is shown;

[0043] Figure 12 A three-dimensional exploded schematic diagram of a radial bearing unit 1 in an embodiment of the present application is shown;

[0044] Figure 13 A three-dimensional cross-sectional view of a radial bearing unit in an embodiment of the present application when a matching structure and a receiving structure abut against each other is shown;

[0045] Figure 14 A three-dimensional cross-sectional view of a radial bearing unit in an embodiment of the present application when a matching structure and a receiving structure are separated is shown;

[0046] Figure 15 for Figure 13 A partial enlarged schematic diagram of part G in the middle;

[0047] Figure 16 for Figure 14 A partial enlarged schematic diagram of the middle H part;

[0048] Figure 17 A three-dimensional cross-sectional schematic diagram of an axial bearing unit in an embodiment of the present application is shown;

[0049] Figure 18 An exploded schematic diagram of an axial bearing unit in an embodiment of the present application is shown;

[0050] Figure 19An exploded view of the top of the main shaft in an embodiment of the present application is shown.

[0051] Description of reference numerals:

[0052] 1. Radial bearing unit 1; 2. First power-off protection unit; 3. Motor unit; 4. Axial bearing unit; 5. Second power-off protection unit; 6. Radial bearing unit 2; 7. Locking mechanism; 8. Spindle; 9. Tool unit; 10. End cover 1; 11. Spindle inner sleeve; 12. Spindle box; 13. Spindle outer sleeve; 14. End cover 2; 101. Pressure cover; 102. Protective cover 1; 103. Bearing seat 1; 104. Iron ring; 105. Coil 1; 106. Bearing inner ring; 107. Permanent magnet core 1; 108. Protective cover 2; 201. Outer cone inner sleeve 1; 202. Bearing inner cover; 203. Bearing outer cover; 204. Bearing frame; 205. Spring; 206. Pin; 207. Rolling bearing 1; 208. Rolling bearing 2; 209. Inner cone outer sleeve 1; 210. First sliding part; 211, inner magnetic core; 212, outer magnetic core; 213, screw one; 214, screw two; 215, screw three; 216, screw four; 301, stator housing; 302, stator core; 303, rotor core; 304, rotor housing; 401, bearing body; 402, permanent magnetic core two; 403, coil two; 404, bearing inner disk; 405, end core one; 406, protective cover three; 407, screw five; 408, end core two; 409, protective cover four; 410, coil three; 411, screw six; 412, screw seven; 501, outer cone inner sleeve two; 502, inner cone outer sleeve two; 503, second sliding part; 504, second spring; 601, cover body; 603, bearing seat two; 610, screw eight; 611, retaining ring; 612, screw nine. DETAILED DESCRIPTION

[0053] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this application will be thorough and complete and will fully convey the concepts of the example embodiments to those skilled in the art. Like reference numerals in the figures represent like or similar structures, and thus their detailed descriptions will be omitted. Furthermore, the figures are merely schematic illustrations of the present application and are not necessarily drawn to scale.

[0054] While relative terms such as "upper" and "lower" are used in this specification to describe the relationship of one illustrated component to another, these terms are used for convenience only, such as in accordance with the orientation of the illustrations in the accompanying drawings. It should be understood that if the illustrated device were flipped upside down, the component described as "upper" would become the component "lower." When a structure is referred to as "on" another structure, this may mean that the structure is integrally formed with the other structure, that the structure is "directly" disposed on the other structure, or that the structure is "indirectly" disposed on the other structure through the other structure.

[0055] The terms "a", "an", "the" and "at least one" are used to indicate the presence of one or more elements / components / etc.; the terms "including" and "having" are used to express open-ended inclusion and mean that additional elements / components / etc. may be present in addition to the listed elements / components / etc.; the terms "first" and "second" are used only as labels and do not limit the quantity of their objects.

[0056] Reference Figure 1 and Figure 2 As shown, in an embodiment of the present application, a spindle system is provided, including: a spindle 8, a radial bearing unit, an axial bearing unit and a power-off protection device.

[0057] In the embodiment of the present application, the spindle system can be applied to both an electric spindle and an air-bearing spindle, without limitation. In the present application, the electric spindle is used as an example for explanation.

[0058] When powered on, the radial bearing unit limits the radial freedom of the main shaft 8, and the axial bearing unit limits the axial freedom of the main shaft 8, so that the main shaft 8 only retains the freedom to rotate around its own axis. When powered off, the restrictions on the main shaft 8 by the radial bearing unit and the axial bearing unit are eliminated.

[0059] In the embodiments of this application, non-contact bearings are used for both the radial and axial bearing units. To achieve spindle levitation, the radial and axial bearing units can employ magnetic bearings, pneumatic bearings, or hydrostatic bearings. When powered, magnetic bearings generate an electromagnetic field to levitate the spindle; hydrostatic bearings utilize a high-pressure oil film to support the spindle; and pneumatic bearings utilize compressed air to create an air layer to achieve spindle levitation. It should be understood that the aforementioned bearings are merely illustrative of non-contact bearings and are not intended to be limiting.

[0060] Furthermore, the spindle system further includes a tool unit 9, a motor unit 3, a locking mechanism 7, sensors and wires (the sensors and wires are not shown in the schematic diagram).

[0061] In the embodiment of the present application, the spindle system further includes a spindle inner sleeve 11, a spindle housing 12, and a spindle outer sleeve 13. The spindle inner sleeve 11 is fixedly mounted on the inner wall of the spindle outer sleeve 13, and the spindle outer sleeve 13 is fixedly mounted on the inner wall of the spindle housing 12. At least one of the outer wall of the spindle inner sleeve 11 and the inner wall of the spindle outer sleeve 13 is provided with a groove, through which gas or liquid can flow, thereby maintaining the spindle 8 at a suitable operating temperature through air or liquid cooling. In the present application, the groove is provided on the outer wall of the spindle inner sleeve 11, but this is not intended to be limiting. The spindle 8 is the central portion of the spindle housing 12, and the spindle 8 vertically extends through both ends of the spindle housing 12.

[0062] Reference Figure 3 、 Figure 4 and Figure 9 As shown, in this embodiment of the present application, the spindle system further includes a first bearing seat 103 and a second bearing seat 603. The first bearing seat 103 is disposed below the spindle inner sleeve 11, and the second bearing seat 603 is disposed above the spindle inner sleeve 11. The first bearing seat 103 is fixedly connected to the spindle inner sleeve 11 by a first screw 213; the second bearing seat 603 is fixedly connected to the spindle inner sleeve 11 in the same manner.

[0063] Reference Figure 3 and Figure 4 As shown, in the embodiment of the present application, the radial bearing unit includes a first magnetic fitting and a second magnetic fitting. The first magnetic fitting is coaxially fixedly mounted on the circumferential outer side of the main shaft 8; the second magnetic fitting coaxially surrounds the outer side of the first magnetic fitting and forms a uniform radial gap between the first magnetic fitting and the second magnetic fitting. The magnetic forces of the first and second magnetic fittings in all circumferential directions are equal. Therefore, it can be understood that the magnetic interaction between the first and second magnetic fittings in all circumferential directions remains balanced. When the main shaft 8 rotates, the first magnetic fitting rotates synchronously with the main shaft 8. Because the magnetic forces of the second magnetic fitting on the first magnetic fitting in all radial directions are equal, stable radial dynamic balance can be achieved within the second magnetic fitting.

[0064] Based on the above structure, a uniform radial gap is formed between the first magnetic fitting and the second magnetic fitting, completely avoiding mechanical contact, thereby significantly reducing friction loss and extending the service life of the bearing. At the same time, this structure achieves the effect of suspension through magnetic force, which can effectively eliminate the vibration caused by the contact of mechanical parts in traditional technologies, ensuring high operational stability, and is particularly suitable for high-speed, high-precision processing scenarios. In addition, this solution achieves self-stabilizing suspension through optimized magnetic force distribution, without relying on complex active control systems, which not only saves installation space, but also significantly reduces system complexity and manufacturing costs.

[0065] Reference Figure 7As shown, in the embodiment of the present application, the axial bearing unit 4 includes an upper magnetic fitting, a lower magnetic fitting, and an intermediate magnetic fitting. The upper magnetic fitting, the lower magnetic fitting, and the intermediate magnetic fitting are all coaxially sleeved on the outside of the main shaft 8 in the circumferential direction. The intermediate magnetic fitting is relatively fixed to the main shaft 8 and is located between the upper magnetic fitting and the lower magnetic fitting. An axial gap is formed between the upper magnetic fitting and the intermediate magnetic fitting, and an axial gap is also formed between the lower magnetic fitting and the intermediate magnetic fitting. Therefore, the intermediate magnetic fitting is suspended by magnetic force and is located in the axial space formed by the upper magnetic fitting and the lower magnetic fitting. When the main shaft 8 is in operation, the fixed intermediate magnetic fitting rotates synchronously therewith. The non-contact design avoids mechanical wear and achieves axial dynamic balance. The free axial suspension and stable operation of the main shaft 8 are achieved, which is particularly suitable for rotating mechanical systems that require high-precision axial positioning.

[0066] In summary, the embodiment of the present application realizes a non-contact magnetic suspension support system by using the axial bearing unit 4 in conjunction with the radial bearing unit. Compared with other bearing support technologies, it has the following significant advantages:

[0067] Compared with rolling bearings: it eliminates mechanical friction, thus eliminating the heat and vibration generated when mechanical parts rotate and contact, so it can have a smooth, high-speed and high-precision effect.

[0068] Compared with hydrostatic bearings: no hydraulic pump power consumption, the hydraulic system is eliminated, which reduces the high cost of construction, high operating cost, high maintenance cost, and also reduces the area required.

[0069] Compared with air bearings: it not only ensures the rigidity and cutting ability of the main shaft 8 itself, but also does not require the use of complex control systems and high-speed rotation, and there is no friction between mechanical parts, so it not only reduces the manufacturing cost, but also effectively reduces the noise problem during equipment operation.

[0070] Reference Figure 3 、 Figure 4 and Figure 9 As shown, in the embodiment of the present application, two radial bearing units are provided, one at the top and one at the bottom of the main shaft 8. Specifically, the radial bearing unit located at the bottom of the main shaft 8 is radial bearing unit 1, and the radial bearing unit located at the top of the main shaft 8 is radial bearing unit 2 6. Of course, this is not restrictive. To further improve the operating stability of the main shaft 8, three, four, or even more radial bearing units may be provided.

[0071] In the embodiment of the present application, there are two optional schemes for the magnetic pole configuration of the first magnetic matching member and the second magnetic matching member:

[0072] Homopolar configuration: When the two magnetic components use the same magnetic poles, the second magnetic component exerts a balanced attraction on the first magnetic component in all radial directions, thereby achieving a balanced state of the main shaft 8.

[0073] Different-pole configuration scheme: When the two adopt opposite magnetic poles, the second magnetic matching component exerts a balanced repulsive force on the first magnetic matching component in all radial directions, which can also achieve a balanced state of the main shaft 8.

[0074] In this application, the first and second magnetic fittings preferably utilize like-pole magnets. This is because, if the gaps between the first and second magnetic fittings become unequal, the suction force will increase dramatically where the gap is smaller, while the suction force will decrease where the gap is larger. This will cause one side of the first and second magnetic fittings to immediately become stuck together. In other words, feedback correction is impossible. Only repulsive force, when the distance is small, increases the repulsive force, creating a natural negative feedback loop that keeps the spindle 8 at the target center.

[0075] In the embodiments of the present application, the upper and middle magnetic mating members can be configured with either the same polarity or different polarity; the same applies to the lower and middle magnetic mating members. However, in the embodiments of the present application, the upper and middle magnetic mating members are preferably configured with the same polarity, and the lower and middle magnetic mating members are also configured with the same polarity. The reason for this is the same as the reason for the first and second magnetic mating members using the same polarity, and will not be elaborated here.

[0076] Reference Figure 4 、 Figure 11 and Figure 12 As shown, in the radial bearing unit 1 of the present embodiment, the first magnetic coupling component comprises a bearing inner ring 106 and a permanent magnetic core 107; the second magnetic coupling component comprises an iron ring 104 and a coil 105. The radial bearing unit 1 also includes a protective cover 102, a second protective cover 108, and a set of sensors. The bearing seat 103 is mounted on the outer sides of the first and second magnetic coupling components. When the bearing inner ring 106 is mounted on and fixedly connected to the main shaft 8, the permanent magnetic core 107 is embedded in the circumferential outer wall of the bearing inner ring 106. The iron ring 104 is fixedly mounted within the bearing seat 103, and the bearing seat 103 is fixedly connected to the main shaft inner sleeve 11.

[0077] Furthermore, the iron ring 104 is an inner claw type circular ring structure, the end of each inner claw of the iron ring 104 is a concentric circular arc structure, the coil 105 is wound on each inner claw of the iron ring 104, the iron ring 104 is provided with at least three inner claws, and a bearing gap is provided between the iron ring 104 and the bearing inner ring 106.

[0078] Furthermore, the permanent magnetic core 107 is composed of multiple permanent magnets, and the magnetic poles of the permanent magnetic core 107 face the iron ring 104. Furthermore, the protective cover 102 and the protective cover 2 108 are provided at both ends of the iron ring 104 to protect the coil 105.

[0079] In the embodiment of the present application, the structure of the radial bearing unit 2 6 is exactly the same as that of the radial bearing unit 1 , and therefore will not be described in detail.

[0080] In this embodiment, a gland 101 and an end cap 10 are positioned below radial bearing unit 1 to support and shield radial bearing unit 1. Gland 101 fits over the outside of spindle 8 and is located directly below the bearing inner ring 106 at the bottom of spindle 8. Gland 101 is bolted to the bearing inner ring 106. End cap 10 fits over the outside of gland 101. Together, gland 101 and end cap 10 form a labyrinthine structure to ensure a seal at the lower end of spindle 8.

[0081] Reference Figure 3 and Figure 7 As shown, in the embodiment of the present application, in the axial bearing unit 4, the lower magnetic mating component includes end core 1 405 and coil 2 403; the middle magnetic mating component includes bearing inner disk 404 and permanent magnetic core 2 402; and the upper magnetic mating component includes end core 2 408 and coil 3 410. In addition to the above, the axial bearing unit 4 also includes a bearing body 401, a third protective cover 406, a fifth screw 407, a fourth protective cover 409, a sixth screw 411, a seventh screw 412, and a set of sensors.

[0082] The bearing inner disk 404 is mounted on the main shaft 8 and is fixedly connected to the main shaft 8. The permanent magnetic core 2 402 is embedded in the inner disk 404 of the bearing. Along the axial direction of the main shaft 8, the lower part of the bearing inner disk 404 is the end core 1 405, and the upper part is the end core 2 408. The coil 2 403 is wound inside the end core 1 405, and the coil 3 410 is wound inside the end core 2 408. The end core 1 405 is connected to the bearing body 401 by screw 5 407. Fixed, the end iron core 2 408 is connected and fixed to the bearing body 401 by screw 6 411, and the bearing body 401 is fixed to the inner sleeve of the main shaft 8 by screw 7 412. The protective cover 3 406 is arranged under the coil 2 403 and is connected and fixed to the end iron core 1 405. The protective cover 3 406 is used to protect the coil 2 403; the protective cover 409 is arranged above the coil 3 410 and is connected and fixed to the end iron core 2 408. The protective cover 409 is used to protect the coil 3 410.

[0083] Reference Figure 17 and Figure 18As shown, further, the permanent magnetic core 2 402 is a multi-piece permanent magnet structure, and the magnetic poles of the permanent magnetic core 2 402 are respectively directed toward the end core 1 405 and the end core 2 408. When the coil 2 403 and the coil 3 410 are energized, a magnetic field is generated after the end core 1 405 and the end core 2 408. The N pole of the permanent magnetic core 2 402 is aligned with the N pole of the end core 1 405 or the end core 2 408 at one end, and the S pole of the permanent magnetic core 2 402 is aligned with the S pole of the other end of the end core 1 405 or the end core 2 408. The axial freedom of the permanent magnetic core 2 402 is limited by the magnetic fields and magnetic forces at both ends, thereby forming an axial bearing unit 4.

[0084] Reference Figure 3 、 Figure 5 and Figure 8 As shown, in the embodiment of the present application, the power-off protection device is used to limit the axial and radial freedom of the main shaft 8 when the power is off, and includes: a first power-off protection unit 2 and a second power-off protection unit 5.

[0085] Reference Figure 3 and Figure 5 As shown, in the embodiment of the present application, the first power-off protection unit 2 includes:

[0086] A matching portion, fixed on the main shaft 8;

[0087] The receiving portion is coaxially sleeved on the outer periphery of the mating portion and located below the mating portion, and has a coupling surface that forms a friction pair with the mating portion, realizes torque transmission with the mating portion when coupled and provides an upward supporting force for the mating portion and the main shaft;

[0088] The first sliding portion 210 is coaxially sleeved on the outer periphery of the receiving portion, forming a rotation pair with the receiving portion and forming an axial linkage fit;

[0089] a biasing member acting on the first sliding portion 210 and applying an upward biasing force to the first sliding portion 210 in the axial direction, so as to drive the first sliding portion 210 to move toward the mating portion, so that the receiving portion and the mating portion are in a combined state;

[0090] The pressurizing mechanism generates a force opposite to the biasing force in a power-on state, and the force is greater than the biasing force, so as to release the combined state; and the force is eliminated in a power-off state.

[0091] Furthermore, when coil one 105, coil two 403 and coil three 410 are energized, the first sliding portion 210 drives the receiving portion away from the mating portion, so that the receiving portion is separated from the mating portion (at this time, the biasing member is in a compressed energy storage state); when coil one 105, coil two 403 and coil three 410 are de-energized, the pressurizing structure eliminates the pressure on the first sliding portion 210, and the biasing member releases the biasing force so that the first sliding portion 210 drives the receiving portion to move upward to approach the mating portion, so that the receiving portion abuts against the mating portion, thereby providing an upward support force for the mating portion and the main shaft 8.

[0092] By incorporating the first power-off protection unit 2, when the electromagnetic coils (coil 1 105, coil 2 403, coil 3 410) lose power (e.g., due to a sudden power outage, control system failure, or device shutdown), the first power-off protection unit 2 intervenes, supporting the main shaft 8 through the abutment between the receiving and mating portions. The main shaft 8 continues to rotate due to inertia, driving the mating and receiving portions along with it, while the first sliding portion 210 remains stationary. This prevents the main shaft 8 from losing control or being damaged due to a loss of buoyancy, thereby improving the system's safety and fault tolerance.

[0093] Furthermore, the first power-off protection unit 2 also includes a mechanical bearing to achieve a more stable and controllable bearing switching mechanism. The mechanical bearing surrounds the receiving portion and the first sliding portion 210; the inner ring of the mechanical bearing is relatively fixed to the receiving portion, and the outer ring of the mechanical bearing is relatively fixed to the first sliding portion 210. In this embodiment of the present application, the first sliding portion 210 is configured as a bearing sleeve.

[0094] Furthermore, two mechanical bearings are provided, each of which is a paired angular contact ball bearing and is provided with a preload. Specifically, the two mechanical bearings are rolling bearing 1 207 and rolling bearing 2 208. This preload eliminates the clearance between the two bearings, improving the radial and axial stiffness of spindle 8 and suppressing machining vibration. The paired angular contact ball bearings can simultaneously withstand radial and bidirectional axial forces, adapting to complex cutting conditions. This ensures the high precision and stability of the power-off protection unit.

[0095] In the embodiment of the present application, the spindle system further includes a bearing frame 204 , which surrounds the outer side of the first sliding portion 210 and is fixedly connected to the spindle inner sleeve 11 , providing a stable support structure for the overall power-off protection unit.

[0096] In the first power-off protection unit 2, the mating part is set as an outer cone inner sleeve 201, and the outer periphery of the bottom of the outer cone inner sleeve 201 has a conical surface that closes from top to bottom; the receiving part is set as an inner cone outer sleeve 209, and the inner periphery of the top of the inner cone outer sleeve 209 has a bonding surface that closes from top to bottom, and the bonding surface matches the conical surface to form a disengageable conical friction pair.

[0097] The biasing member is configured as a first spring 205, which is disposed at the top of the bearing frame 204 to apply an upward elastic force to the first sliding portion 210. A plurality of first springs 205 are distributed circumferentially along the bearing frame 204 and the first sliding portion 210. The first spring 205 further adopts a butterfly spring, which is disposed between the end faces of the bearing frame 204 and the first sliding portion 210.

[0098] In the embodiment of the present application, the pressurizing mechanism includes:

[0099] The inner magnetic core 211 is fixedly disposed outside the circumferential side wall of the first sliding portion 210;

[0100] The outer magnetic core 212 is fixed on the inner side of the bearing frame 204 and surrounds the outer side of the inner magnetic core 211. There is a gap between the outer magnetic core 212 and the inner magnetic core 211. When the outer magnetic core 212 is energized, it can react with the inner magnetic core 211 to generate a magnetic pole reaction, and drive the receiving part and the first sliding part 210 to overcome the bias force and move away from the mating structure along the axial direction of the main shaft 8 (the receiving part and the mating part are separated).

[0101] When the electromagnetic coils (Coil 1 105, Coil 2 403, and Coil 3 410) are energized, the outer magnetic core 212 is synchronously excited, generating a magnetic repulsive force between it and the inner magnetic core 211. This forces the inner magnetic core 211, along with the first sliding portion 210 and the receiving portion connected thereto, axially away from the mating structure of the main shaft 8. This overcomes the preload force of the biasing member and causes the inner cone outer sleeve 1 209 to move downward and separate from the outer cone inner sleeve 1 201. At this point, the main shaft 8 is supported solely by the magnetic bearings, achieving frictionless, high-speed operation.

[0102] When the electromagnetic coils (coil 105, coil 2 403, and coil 3 410) are de-energized, outer magnetic core 212 is simultaneously demagnetized, and first spring 205 releases its upward force, driving first sliding portion 210 and inner-cone outer sleeve 1 209 to reset axially along spindle 8 until inner-cone outer sleeve 1 209 abuts outer-cone inner sleeve 1 201. At this point, spindle 8 transmits torque through friction between inner-cone outer sleeve 1 209 and outer-cone inner sleeve 1 201, providing a secure support.

[0103] Furthermore, the inner magnetic core 211 is a permanent magnet, and the outer magnetic core 212 is a coil, which has a simple structure, strong magnetic force, stable operation, and is easy to control.

[0104] In this embodiment of the present application, the first power-off protection unit 2 further includes a bearing inner cover 202, a bearing outer cover 203, a second screw 214, a third screw 215, and a fourth screw 216. The bearing inner cover 202 and the bearing outer cover 203 form a labyrinth seal at one end of the power-off protection unit, while the receiving portion and the end of the first sliding portion 210 form a labyrinth seal at the other end of the power-off protection unit, protecting the power-off protection unit while also preventing small debris from the bearing from scattering outward. The bearing frame 204 is fixedly connected to the bearing seat 103 via a second screw 214, the bearing outer cover 203 is fixedly connected to the first sliding portion 210 via a third screw 215, and the bearing inner cover 202 is fixedly connected to the receiving portion via a fourth screw 216.

[0105] Reference Figure 3 、 Figure 5 、 Figure 8 、 Figure 13 、 Figure 14 、 Figure 15 and Figure 16 As shown, in the embodiment of the present application, the structures of the first power-off protection unit 2 and the second power-off protection unit 5 are exactly the same. The two are arranged in radial mirror images of the main shaft 8, and the first power-off protection unit 2 is located below the second power-off protection unit 5.

[0106] Specifically, the second power-off protection unit 5 includes:

[0107] The outer cone inner sleeve 501 has an outer periphery that is in a wide-mouthed cone shape from top to bottom.

[0108] The inner cone outer sleeve 502 has a second joint surface which is also in a wide cone shape from top to bottom.

[0109] The second sliding portion 503 is coaxially sleeved on the outer periphery of the inner cone outer sleeve 502, forming a rotation pair with the receiving portion and forming an axial linkage fit;

[0110] The second spring 504 is disposed at the bottom of the bearing frame 204 and applies a downward elastic force to the second sliding portion 503 .

[0111] In addition, the second power-off protection unit 5 also has other structures identical to those of the first power-off protection unit 2, such as the pressure mechanism and mechanical bearing. The operating principles of these structures are exactly the same as those of the first power-off protection unit 2, and therefore will not be described in detail. It should be understood that the biasing force provided by the second spring 504 in the second power-off protection unit 5 is in the opposite direction to the biasing force of the first spring 205 in the power-off protection unit 2, and the force provided by the pressure mechanism in the second power-off protection unit 5 is in the opposite direction to the force provided by the pressure mechanism in the first power-off protection unit 2.

[0112] Through the coordinated operation of the first power-off protection unit 2 and the second power-off protection unit 5, when the outer magnetic core 212 is powered off and demagnetized, the spring 205 in the first power-off protection unit 2 releases its elastic force, driving the outer cone inner sleeve 1 201 and the first sliding portion 210 upward, allowing the receiving structure of the outer cone inner sleeve 1 201 to abut against the mating structure of the inner cone outer sleeve 1 209. The second spring 503 in the second power-off protection unit 5 releases its elastic force, driving the outer cone inner sleeve 2 501 and the second sliding portion 503 downward, allowing the outer cone inner sleeve 2 501 to abut against the inner cone outer sleeve 2 502. The outer cone inner sleeve 1 201 and the inner cone outer sleeve 1 209 prevent the spindle 8 from moving downward in the axial direction, while the outer cone inner sleeve 2 501 and the inner cone outer sleeve 2 502 prevent the spindle 8 from moving upward in the axial direction. This restricts the spindle 8 in the axial direction, ensuring stable rotation of the spindle 8 after the outer magnetic core 212 is powered off and demagnetized.

[0113] Reference Figure 3 and Figure 6 As shown, in the embodiment of the present application, the motor unit 3 includes a stator housing 301, a stator core 302, a rotor housing 304 and a rotor core 303. The stator core 302 is mounted on the inner side of the stator housing 301, and the rotor core 303 is fixed to the outer side of the rotor housing 304. The rotor housing 304 is sleeved on the main shaft 8 and fixedly connected to the main shaft 8. The stator core 302 is an iron core and a coil, and the rotor core 303 is a permanent magnet structure. When the coil is energized, the iron core can react with the rotor core 303 to cause the rotor core 303 to rotate, and there is a gap between the iron core and the rotor core 303.

[0114] like Figure 2 、 Figure 3 、 Figure 9 、 Figure 10 、 Figure 19 As shown, the locking mechanism 7 at the top of the main shaft 8 includes a cover body 601, screw eight 610, a retaining ring 611 and screw nine 612. The retaining ring 611 is a double semicircular ring structure. The circumferential side wall at the top of the main shaft 8 is provided with a groove adapted to be engaged with the retaining ring 611. The retaining ring 611 is inserted into the groove at the end of the main shaft 8, and the cover body 601 is sleeved on the outside of the retaining ring 611. First, tighten the screw eight 610 to connect and fix the cover body 601 to the bearing inner ring 106 in the radial bearing unit two 6, and then tighten the screw nine 612 to connect and fix the cover body 601 to the retaining ring 611.

[0115] In the embodiment of the present application, the spindle system further includes a second end cover 14 , which is disposed on the top of the spindle 8 .

[0116] Furthermore, the second end cover 14 and the cover body 601 form a labyrinth structure to seal and protect the main shaft 8.

[0117] The spindle system in the embodiment of the present application has the following structural features:

[0118] (1) The spindle system mainly includes a radial bearing unit 1, a first power-off protection unit 2, a motor unit 3, an axial bearing unit 4, a second power-off protection unit 5, a radial bearing unit 2 6, a spindle 8, a tool unit 9, an end cover 10, an inner sleeve 11, an outer sleeve 13 and multiple sets of sensors.

[0119] (2) The overall structure of the spindle system is a suspended structure.

[0120] (3) The power supply used by the spindle system is a servo motor, which can also be a variable frequency motor, an asynchronous motor, or a DC motor, but is not limited to these.

[0121] (4) The spindle 8 of the spindle system is placed at the center of the spindle box 12, and the spindle 8 and the axis of the motor unit 3 are the same axis.

[0122] (5) The spindle system is provided with three sets of magnetic bearings, namely radial bearing unit 1, radial bearing unit 2 6 and axial bearing unit 4, wherein: radial bearing unit 1 and radial bearing unit 2 6 have the same structure, radial bearing unit 1 and radial bearing unit 2 6 are responsible for bearing the radial load of the spindle 8, radial bearing unit 1 and radial bearing unit 2 6 limit the four degrees of freedom of the spindle 8 (front, back, left and right in the horizontal direction, and rotation around the X or Y axis), radial bearing unit 1 and radial bearing unit 2 6 can be respectively set at both ends of the motor unit 3; axial bearing unit 4 is responsible for bearing the axial load of the spindle 8, axial bearing unit 4 limits one degree of freedom of the spindle 8 (movement in the vertical direction), and axial bearing unit 4 can be set at either end of the motor unit 3.

[0123] (6) The spindle system is further provided with a first power-off protection unit 2 and a second power-off protection unit 5. The first power-off protection unit 2 and the second power-off protection unit 5 have the same structure (but it is worth noting that the structures of the two are mirror images in the horizontal direction). The first power-off protection unit 2 and the second power-off protection unit 5 can be respectively arranged at the two ends of the motor unit 3. In other embodiments, the specific positions of the first power-off protection unit 2, the second power-off protection unit 5, the radial bearing unit 1, the radial bearing unit 2 6 and the axial bearing unit 4 are determined according to the structural design.

[0124] (7) The spindle 8 of the spindle system is connected to the tool unit 9. The tool unit 9 can be a milling cutter, a boring cutter, a grinding wheel, a grinding disc or a polishing disc, but is not limited thereto.

[0125] (8) The spindle inner sleeve 11 and the spindle outer sleeve 13 of the spindle system are a set structure. A groove is provided between the spindle inner sleeve 11 and the spindle outer sleeve 13. The groove is a fluid channel for cooling the spindle system.

[0126] (9) The spindle system is a complete component and a key component of CNC wafer processing equipment and machine tools. The spindle inner sleeve 11, the spindle outer sleeve 13, the end cover 10, the end cover 2 14 and the bearing seats at both ends constitute a closed overall structure.

[0127] (10) The radial bearing unit 1, the first power-off protection unit 2, the motor unit 3, the axial bearing unit 4, the second power-off protection unit 5, the radial bearing unit 2 6, the locking mechanism 7, the spindle 8 and the tool unit 9 are all equipped with multiple sensors, including position sensors, force sensors, temperature sensors, etc. The sensors are connected to the CNC module or the CNC system through wires to form a closed-loop control of the overall system.

[0128] In summary, the spindle 8 of the spindle system is placed in the center and passes through both ends. The spindle 8 is the axis of the motor unit 3. The middle part of the spindle 8 is the motor unit 3. The motor unit 3 provides working power for the spindle 8, and the motor unit 3 can drive the spindle 8 to rotate; the spindle 8 is supported by five groups of bearing units, among which: two groups of radial bearing units are responsible for the radial support of the spindle 8, which can limit the four degrees of freedom of the spindle 8; one group of axial bearing units 4 is responsible for the axial support of the spindle 8, which can limit one degree of freedom of the spindle 8; the other degree of freedom of the spindle 8 is the rotational degree of freedom, which is used for work. The rotating elements of the spindle system (such as the inner sleeve, the rotor shell 304) are fixedly connected to the spindle 8, and the stationary elements of the spindle system are fixedly connected to the spindle box 12 (such as the spindle inner sleeve 1 1. Spindle outer sleeve 13, bearing seat 103, bearing seat 2 603, end core 1 405, end core 2 408, stator housing 301, bearing frame 204). A gap, also known as a magnetic gap, is provided between the rotating element and the stationary element of the magnetic bearing unit. When the spindle system is operating, the magnetic gap is maintained by magnetic force and can maintain high precision and stability of movement. Two sets of power-off protection units are used for support and protection when the spindle 8 is not operating and for support and guard when the spindle 8 is operating. The two sets of power-off protection units can limit the six degrees of freedom of the spindle 8. When the magnetic bearing unit is in a stopped state or a power-off state, the magnetic force is released and the power-off protection unit takes over the support. When the power-off protection unit is supporting, the spindle 8 can still rotate freely and can continue to maintain high precision and stability.

[0129] The first power-off protection unit 2 is a main shaft support system based on mechanical bearings. The first power-off protection unit 2 includes a clutch group A, a movable support group B, a fixed support group C, a driving power group D and a control system. The clutch group A is composed of a receiving part (an inner cone outer sleeve 209), a matching part (an outer cone inner sleeve 201) fixed to the main shaft 8, and the receiving part is embedded in the bearing inner sleeve. The receiving part and the matching part are coupling parts. The two sets can be separated and matched. When separated, the two sets are unrelated. When matched, the two sets can maintain stable high precision and high rigidity. The movable support group B is composed of a bearing, a first sliding part 210, a bearing inner cover 202 and a bearing outer cover 203. The mechanical bearing is installed in the first sliding part 210, and the first sliding part 210 is installed in the bearing frame 204. The first sliding part 210 can move up and down in the bearing frame 204. When the first sliding part 210 moves up and down, the mechanical bearing, the bearing inner cover 202, the bearing outer cover 203 and the receiving part are forced to move simultaneously, that is, the movable support group B can drive the receiving part to move. The fixed support group C is composed of a bearing frame 204 and a pin 206. The bearing frame 204 is equipped with a movable support group B. The bearing frame 204 is equipped with a pin 206. The pin 206 is used for limiting. The bearing frame 204 is fixed in the bearing seat, and the bearing seat is fixed at the end of the main shaft inner sleeve 11; the driving power group D is composed of an inner magnetic core 211, an outer magnetic core 212 and a spring 205. The inner magnetic core 211 is embedded in the sliding part 210, and the outer magnetic core 212 is embedded in the bearing frame 204. The inner magnetic core 211 and the outer magnetic core 212 are corresponding parts. After power is applied, they can interact with each other to push the movable support group B to move, so that the inner sleeve of the clutch group A is separated from the receiving part. The spring 205 is installed between the bearing frame 204 and the end face of the sliding part 210. Its function is to push the movable support group B to move and combine the outer cone inner sleeve of the clutch group A with the receiving part.

[0130] The structure and principle of the second power-off protection unit 5 are the same as those of the first power-off protection unit 2 , and therefore are not described in detail.

[0131] When the spindle system is working, two sets of radial bearing units are responsible for the radial support of the spindle, and one set of axial bearing units 4 is responsible for the axial support of the spindle. The magnetic force limits the five degrees of freedom of the spindle (after limiting the movement in the X, Y, and Z directions, and the rotation around X and Y). The other degree of freedom of the spindle is the rotational freedom (rotation around the Y axis), which is used for work; after power is turned on, the three sets of magnetic bearing units work to float the spindle so that the spindle has no rigid contact with any stationary components, and the motor unit 3 runs, and the motor unit 3 drives the spindle to rotate, thereby completing various processing tasks.

[0132] The power-off protection device has two states of existence: one is the support guard state when the spindle is working, and the other is the support guarantee state when the spindle is not working. When the spindle is operating and the power-off protection unit is in the support duty state, the outer magnetic core 212 is always energized. After the outer magnetic core 212 is energized, the inner magnetic core 211 is acted upon by the magnetic force, pushing the movable support group B to move. The movable support group B compresses the spring 205 and separates the inner sleeve of the clutch group A from the receiving portion, thereby disengaging the power-off protection unit from the spindle and preventing the power-off protection unit from participating in the operation of the spindle. When the spindle is not operating or the magnetic bearing experiences an abnormality, the outer magnetic core 212 is de-energized, the magnetic force on the inner magnetic core 211 is released, and the movable support group B moves instantaneously under the action of the spring 205, causing the inner sleeve of the clutch group A to engage with the receiving portion, allowing the power-off protection unit to instantly engage with the spindle. The power-off protection unit quickly takes over the operation of the magnetic bearing. The two sets of power-off protection units simultaneously support the spindle, preventing "hard contact" with the magnetic bearing, thereby protecting the spindle head from damage. When the spindle is not operating, the power-off protection unit is always combined with the spindle, ensuring that the spindle head and the magnetic bearing are always protected.

[0133] The spindle system is controlled by a CNC module or a CNC system. The tool unit 9, the spindle, the motor unit 3, the radial bearing unit, the axial bearing unit 4 and the power-off protection unit are equipped with multiple sensors, including position sensors, force sensors, temperature sensors, etc. The sensors are connected to the CNC module or the CNC system through wires to form a closed-loop control of the overall system.

[0134] In an embodiment of the present application, a thinning machine is also included, which includes any one of the spindle systems described above.

[0135] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and practicing the embodiments of the present invention. This application is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art that are not covered by this application. The specification and embodiments are intended to be exemplary only, and the true scope and spirit of the present invention are indicated by the appended claims.

Claims

1. A power-off protection device, characterized in that: include: A first power-off protection unit, wherein the first power-off protection unit comprises: The matching portion is fixed on the main shaft; a receiving portion, coaxially sleeved on the outer periphery of the mating portion and located below the mating portion, capable of forming a friction pair with the mating portion, realizing torque transmission with the mating portion when engaged, and providing an upward supporting force for the mating portion and the main shaft; A first sliding portion is coaxially sleeved on the outer periphery of the receiving portion, forming a rotation pair with the receiving portion and forming an axial linkage fit; a biasing member acting on the first sliding portion and applying an upward biasing force to the first sliding portion in the axial direction to drive the first sliding portion to move toward the matching portion, so that the receiving portion and the matching portion are in a coupled state; a pressurizing mechanism, which generates a force in the opposite direction to the biasing force in a power-on state, and the force is greater than the biasing force, so as to release the combined state; and the force is eliminated in a power-off state; The mating portion is configured as an outer cone inner sleeve, and the bottom of the outer cone inner sleeve has a conical surface that is closed from top to bottom along the axial direction; the receiving portion is configured as an inner cone outer sleeve, and the top of the inner cone outer sleeve has a bonding surface that is closed from top to bottom along the axial direction, and the bonding surface matches the conical surface to form a disengageable conical friction pair; The pressurizing mechanism comprises: an inner magnetic core fixedly disposed on the outer periphery of the first sliding portion; The outer magnetic core surrounds the outer side of the inner magnetic core, and a radial gap is formed between the outer magnetic core and the inner magnetic core. When the outer magnetic core is energized, it can generate a magnetic pole reaction with the inner magnetic core, and drive the first sliding part and the receiving part to overcome the biasing force and move away from the matching part along the axial direction of the main shaft, so that the receiving part is separated from the matching part.

2. The power-off protection device according to claim 1, characterized in that: It also includes a mechanical bearing, which surrounds the receiving portion and the first sliding portion; the inner ring of the mechanical bearing is relatively fixed to the receiving portion, and the outer ring of the mechanical bearing is relatively fixed to the first sliding portion.

3. The power-off protection device according to claim 2, characterized in that: The mechanical bearings are provided in two numbers, and the two mechanical bearings are angular contact ball bearings and are provided with preload force.

4. The power-off protection device according to claim 1, characterized in that: The first power-off protection unit also includes: a bearing inner cover and a bearing outer cover, the bearing inner cover is fixedly connected to one end of the receiving part, the bearing outer cover is fixedly connected to one end of the first sliding part, the bearing inner cover and the bearing outer cover constitute a labyrinth seal at one end of the first power-off protection unit, and the end portion of the other end of the receiving part and the end portion of the other end of the first sliding part constitute a labyrinth seal at the other end of the first power-off protection unit.

5. The power-off protection device according to any one of claims 1 to 4, characterized in that: It also includes a second power-off protection unit with the same structure as the first power-off protection unit, and the structures of the first power-off protection unit and the second power-off protection unit are arranged in a radial mirror image of the main shaft.

6. A spindle system, characterized in that: It comprises the power-off protection device and the main shaft according to any one of claims 1 to 5.

7. The spindle system according to claim 6, characterized in that Also includes: The radial bearing unit includes a first magnetic fitting and a second magnetic fitting, wherein the first magnetic fitting is fixedly sleeved on the circumferential outer side of the main shaft; the second magnetic fitting surrounds the outer side of the first magnetic fitting and forms a uniform radial gap with the first magnetic fitting, and the magnetic forces of the first and second magnetic fittings in all directions around the main shaft are equal; The axial bearing unit includes an upper magnetic fitting, a lower magnetic fitting and an intermediate magnetic fitting. The upper magnetic fitting, the lower magnetic fitting and the intermediate magnetic fitting are all coaxially sleeved on the circumference of the main shaft. The intermediate magnetic fitting is relatively fixed to the main shaft and is located between the upper magnetic fitting and the lower magnetic fitting; axial gaps are formed between the upper magnetic fitting and the intermediate magnetic fitting, and between the lower magnetic fitting and the intermediate magnetic fitting, respectively.

8. A thinning machine, characterized in that, Comprising the spindle system according to claim 6 or 7.

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