Axial rigidity detection device and method for air floating main shaft

Abstract

The invention discloses a device and a method for detecting the axial rigidity of an air floating main shaft. The device comprises a force application part, a force conduction part, a connecting part, a force sensor and a displacement sensor, the force application part is suitable for generating axial force; the force sensor is arranged between the force application part and the force conduction part and is suitable for recording the value of the axial force; the force transmission piece transmits the axial force to the axial direction of the air floating main shaft through the connecting piece; the connecting piece comprises a bearing, a bearing fixing frame, a first baffle and a connecting plate, the bearing fixing frame is of a hollow structure, the bearing is nested in the hollow structure, and the bottom of the bearing fixing frame is fixedly connected with the connecting plate; one side, far away from the force sensor, of the force conduction piece extends into the hollow structure and is nested in the inner ring of the bearing, and the force conduction piece is fixedly connected with the bearing through a first baffle plate; the air floating main shaft is fixedly connected with the connecting plate, and the displacement sensor is arranged at the position close to the air floating main shaft and is suitable for collecting the displacement amount of the air floating main shaft in the axial direction under the action of axial force.

Description

Technical Field

[0001] The invention relates to the field of bearing detection, and in particular to an axial stiffness detection device and method for an air-floating main shaft. Background Art

[0002] Air-floating spindles are widely used in ultra-precision fields such as semiconductors, optical manufacturing, and micro-nano processing. In dynamic processing, load fluctuations will change the air film thickness of the air-floating spindle, thereby affecting the axial stiffness. Compared with static stiffness, the dynamic stiffness of the air-floating spindle can better reflect the load-bearing characteristics of the air-floating spindle in the working state, ensuring that the main air-floating spindle always maintains sufficient stiffness during operation, reducing processing errors caused by stiffness changes, and improving the surface quality and shape accuracy of the workpiece.

[0003] In engineering, existing detection devices either use cylinders to apply axial force, which makes the detection device larger and difficult to apply stable axial force; or use electromagnetics to apply axial force, which makes the detection device complex and costly; or use complex transmission devices to apply axial force, which has high precision but is troublesome to operate and assemble, and difficult to maintain. Moreover, most of them need to purchase related customized parts, with long delivery cycles and high costs. It is difficult to meet the requirements of simple, convenient, fast, and as low-cost as possible detection of dynamic axial stiffness in engineering.

[0004] How to quickly, conveniently, efficiently, accurately and economically detect the dynamic axial stiffness of the air-bearing spindle, make the workpiece easy to process and assemble, and be compatible with different air-bearing spindles without modification or with simple modification, is a challenge faced in engineering. Summary of the invention

[0005] In view of the above problems, the present invention is proposed to provide an axial stiffness detection device and method for an air-bearing spindle that overcomes the above problems or at least partially solves the above problems.

[0006] According to one aspect of the present invention, there is provided an axial stiffness detection device for an air-floating spindle, comprising: a force-applying component, a force transmission component, a connecting component, a force sensor and a displacement sensor; the force-applying component is suitable for generating an axial force; the force sensor is arranged between the force-applying component and the force transmission component, and is suitable for recording the value of the axial force; the force transmission component transmits the axial force to the axial direction of the air-floating spindle through the connecting component; the connecting component comprises a bearing, a bearing fixing frame, a first baffle plate and a connecting plate, the bearing fixing frame is a hollow structure, the bearing is nested in the hollow structure, and the bottom of the bearing fixing frame is fixedly connected to the connecting plate, wherein an empty space is formed between the bearing fixing frame, the bearing and the connecting plate; the force transmission component extends into the hollow structure on a side away from the force sensor, and is nested in an inner ring of the bearing, and the force transmission component is fixedly connected to the bearing through the first baffle plate, wherein the first baffle plate is in the empty space, and does not abut against the bearing fixing frame and the connecting plate; the air-floating spindle is fixedly connected to the connecting plate, and the displacement sensor is arranged at a position close to the air-floating spindle, and is suitable for collecting the displacement of the air-floating spindle in the axial direction under the action of the axial force.

[0007] Optionally, in the axial stiffness detection device of the air-floating spindle according to the present invention, a limiting portion is formed inside the hollow structure of the bearing fixing frame, and the bearing abuts against the limiting portion, so that an empty space is formed between the bearing fixing frame, the bearing and the connecting plate.

[0008] Optionally, in the axial stiffness detection device of the air-floating spindle according to the present invention, the connecting member further includes a second baffle, which is fixed to a side of the hollow structure away from the connecting plate and is suitable for fixing the bearing between the top of the hollow structure and the limiting portion.

[0009] Optionally, in the axial stiffness detection device of the air-floating spindle according to the present invention, the spindle fixing frame includes a bearing plate and multiple support plates, the multiple support plates are fixedly connected to the bearing plate, a through hole is formed on the bearing plate, and multiple fixed threaded holes are formed around the through hole, the air-floating spindle partially passes through the through hole, and the air-floating spindle is fixed to the spindle fixing frame through the multiple fixed threaded holes.

[0010] Optionally, in the axial stiffness detection device for the air-floating spindle according to the present invention, a plurality of groups of connecting threaded holes are formed on the connecting plate, the connecting plate is fixedly connected to the air-floating spindle through each connecting threaded hole, and any group of connecting threaded holes is compatible with a model of the air-floating spindle.

[0011] Optionally, in the axial stiffness detection device for the air-floating spindle according to the present invention, the force applying component is a force applying screw.

[0012] Optionally, in the axial stiffness detection device of the air-floating spindle according to the present invention, it also includes: a force-applying component fixing frame, including a mounting plate and a plurality of support columns; one end of each support column is fixed to the bearing plate, and the other end is fixed to the mounting plate; a force-applying threaded hole is formed at the center of the mounting plate, and the force-applying component passes through the force-applying threaded hole and abuts against the force sensor.

[0013] Optionally, the axial stiffness detection device of the air-floating spindle according to the present invention further comprises: a magnetic base, one end of which is fixed to the bearing plate or the air-floating spindle housing by magnetic means, and the other end of which is fixed to the displacement sensor.

[0014] Optionally, in the axial stiffness detection device for the air-floating spindle according to the present invention, the spindle fixing frame further comprises a rib plate arranged between the support plate and the bearing plate.

[0015] Optionally, in the axial stiffness detection device for the air-bearing main shaft according to the present invention, the bearing includes a first sub-bearing and a second sub-bearing, and the first sub-bearing and the second sub-bearing are angular contact ball bearings.

[0016] Optionally, in the axial stiffness detection device for the air-floating main shaft according to the present invention, the first sub-bearing and the second sub-bearing are installed in a back-to-back duplex.

[0017] According to another aspect of the present invention, there is provided a method for detecting the axial stiffness of an air-floating spindle, which is suitable for being implemented by the above-mentioned device, and the method comprises: when the air-floating spindle is in a static state, applying a first axial force to the air-floating spindle, and recording a first displacement of the air-floating spindle in an axial direction; when the air-floating spindle is in a first dynamic state, applying a second axial force to the air-floating spindle, and recording a second displacement of the air-floating spindle in an axial direction; when the air-floating spindle is in a second dynamic state, applying a third axial force to the air-floating spindle, and recording a third displacement of the air-floating spindle in an axial direction, wherein the rotation speed of the air-floating spindle in the second dynamic state is greater than the rotation speed in the first dynamic state; and calculating the axial stiffness of the air-floating spindle in different states by respectively using the first axial force, the first displacement, the second axial force, the second displacement, the third axial force, and the third displacement.

[0018] Optionally, in the axial stiffness detection method of the air-floating spindle according to the present invention, the first axial force, the first displacement, the second axial force, the second displacement, the third axial force, and the third displacement are respectively used to calculate the axial stiffness of the air-floating spindle in different states, including: for a target state, the ratio of the axial force to the axial displacement in the target state is used as the axial stiffness of the air-floating spindle in the target state.

[0019] According to the solution of the present invention, the axial stiffness detection device of the air-floating spindle has a simple and compact structure, a small size, a stable axial force applied, and is easy to control. Only simple tooling is required to conveniently and quickly detect the dynamic axial stiffness of the air-floating spindle, meet the accuracy requirements, and be compatible with a variety of spindles.

[0020] The axial stiffness detection device for the air-floating spindle of the present invention is simple to manufacture, convenient to assemble and replace, greatly reduces the difficulty and cost of detecting the overall dynamic axial stiffness, and is suitable for measuring the overall dynamic axial stiffness of the air-floating spindle in engineering.

[0021] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0023] Figure 1 A front view of an axial stiffness detection device 100 for an air-bearing spindle according to an embodiment of the present invention is shown;

[0024] Figure 2 An isometric schematic diagram of an axial stiffness detection device 100 for an air-bearing spindle according to an embodiment of the present invention is shown;

[0025] Figure 3 shows an isometric schematic diagram of a spindle mount 160 according to one embodiment of the present invention;

[0026] Figure 4 A schematic diagram of a cross section AA of a front view of a connecting member 130 according to an embodiment of the present invention is shown;

[0027] Figure 5 An isometric schematic diagram of a support column 172 is shown according to one embodiment of the present invention;

[0028] Figure 6 A side view of a magnetic stand 180 is shown according to one embodiment of the present invention;

[0029] Figure 7 A schematic structural diagram of an air-floating spindle 200 according to an embodiment of the present invention is shown;

[0030] Figure 8A schematic flow chart of an axial stiffness detection method 300 of an air-bearing spindle according to an embodiment of the present invention is shown;

[0031] Fig. 9 A schematic diagram of the assembly process of an axial stiffness detection device 100 for an air-bearing spindle according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0032] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0033] Figure 1 A front view of an axial stiffness detection device 100 for an air-bearing spindle according to an embodiment of the present invention is shown. Figure 2 FIG. 1 is an isometric diagram of an axial stiffness detection device 100 for an air-bearing spindle according to an embodiment of the present invention. Figure 3 An isometric schematic diagram of a spindle mount 160 is shown in accordance with one embodiment of the present invention. Figure 4 A schematic diagram of the cross section AA of a front view of a connecting member 130 according to an embodiment of the present invention is shown. Figure 5 An isometric schematic diagram of a support column 172 is shown in accordance with one embodiment of the present invention. Figure 6 A side view of a magnetic stand 180 is shown in accordance with one embodiment of the present invention. Figure 7 A schematic structural diagram of an air-bearing spindle 200 according to an embodiment of the present invention is shown.

[0034] like Figure 1 As shown, the device 100 includes a force-applying component 110 , a force transmission component 120 , a connecting component 130 , a force sensor 140 , a displacement sensor 150 , a spindle fixing frame 160 , a force-applying component fixing frame 170 , and a magnetic base 180 .

[0035] The spindle fixing frame 160 is suitable for fixing the air-floating spindle 200 to be tested. The spindle fixing frame 160 includes a bearing plate 161, a plurality of support plates 162 and a rib plate 163. One side of the support plate 162 is fixedly connected to the bearing plate 161 by screws, and the other side opposite is placed on the ground to support the bearing plate 161. The rib plate 163 is in the shape of a "right-angled trapezoid", and its two mutually perpendicular sides are fixedly connected to the support plate 162 and the bearing plate 161 respectively, and the rib plate 161 plays a fixed supporting role to stabilize the entire structure.

[0036] A through hole is formed in the center of the carrier plate 161 , and the user fixes the air-floating spindle 200 . A plurality of sets of fixing threaded holes are formed around the through hole to adapt to different models of air-floating spindles 200 .

[0037] The air-floating spindle 200 includes a spindle rotor 210 and a shell 220. The shell 220 includes the spindle rotor 210 and is used to protect the spindle rotor 210. A flange assembly 221 is formed on the shell 220. The flange assembly 221 has multiple threaded holes. The air-floating spindle 200 is vertically fixed to the supporting plate 161 through these threaded holes and the fixed threaded holes on the supporting plate 161.

[0038] The spindle rotor 210 is connected to the connecting member 130. The connecting member 130 includes a bearing 131, a bearing fixing frame 132, a first baffle 133, a connecting plate 134 and a second baffle 135. The connecting plate 134 is arranged on the top of the spindle rotor 210, and a plurality of connecting threaded holes are formed on the connecting plate 134. The connecting plate 134 is fixedly connected to the spindle rotor 210 through each connecting threaded hole, and any one group of connecting threaded holes is compatible with a model of the air-floating spindle 200.

[0039] The bearing fixing frame 132 is fixedly connected to the connecting plate 134 . The bearing fixing frame 132 is a hollow structure. The bearing 131 is nested in the hollow structure. The hollow structure includes a base and a main body. The base is connected to the connecting plate 134 , and the bearing 131 is nested in the main body.

[0040] In some embodiments, a limiting portion is formed on the inner side wall of the main body, and the bearing 131 abuts against the limiting portion, so that an empty space is formed between the bearing 131 , the connecting plate 134 and the bearing fixing frame 132 .

[0041] The second baffle 135 is arranged at the entrance of the main body (ie, the top of the bearing fixing frame 132 ), covers the main body, and extends from the main body, so as to clamp the bearing 131 between the entrance of the main body and the limiting portion.

[0042] In some embodiments, the bearing 131 is composed of a first sub-bearing and a second sub-bearing, and the first sub-bearing and the second sub-bearing are angular contact ball bearings, wherein the first sub-bearing and the second sub-bearing are installed in back-to-back duplex.

[0043] It is easy to understand that angular contact ball bearings can bear radial loads and axial loads at the same time and can work at higher speeds. There are raceways on the inner and outer rings of angular contact ball bearings, and the inner and outer rings can make relative displacements along the axial direction of the bearing.

[0044] The force transmission member 120 is arranged between the connecting member 130 and the force applying member 110, and is used to transmit the axial force generated by the force applying member 110 to the air-floating main shaft 200 through the connecting member 130. The force transmission member 120 includes a truncated cone and a cylinder. The front end of the cylinder extends into the bearing fixing frame 132 and is nested in the inner ring of the bearing 131. The bottom of the cylinder is sleeved with the bearing 131 through the first baffle plate 133, wherein the first baffle plate 133 is located in the above-mentioned vacant space, so that the first baffle plate 133 does not abut against the bearing fixing frame 132 and the connecting plate 134. In this way, when the air-floating main shaft 200 is under the rotating turntable, only the connecting plate 134 and the bearing fixing frame 132 are driven to rotate, and the force transmission member 120 does not rotate under the action of the bearing 131, so as to avoid the problem that when the axial stiffness of the air-floating main shaft 200 is dynamically measured, the rotation of the air-floating main shaft 200 causes the axial force transmitted by the force transmission member 120 to be inaccurate, thereby causing a large deviation in the measurement result.

[0045] The force sensor 140 is arranged on the truncated cone of the force transmission member 120. The force applying component 110 is arranged on a side of the force sensor 140 away from the truncated cone.

[0046] The force applying member 110 is adapted to generate an axial force, and the force sensor 140 is adapted to record the axial force.

[0047] In some embodiments, the force-applying component 110 may be a force-applying screw, and the force-applying component fixing frame 170 is used to fix the force-applying component 110, which includes a mounting plate 171, a plurality of support columns 172 and a fixing pin 173. One end of the support column 172 is fixed on the mounting plate 171, and the other end is fixed on the bearing plate 161. A force-applying threaded hole is formed in the center of the mounting plate 171, and the force-applying component 110 abuts against the force sensor 140 after passing through the force-applying threaded hole. By screwing the force-applying component 110, a stable axial force is provided to the air-floating main shaft 200. The fixing pin 173 is used to limit the force transmission component 120, which is arranged between the mounting plate 171 and the force transmission component 120. When the air-floating main shaft 200 is performing axial stiffness detection, the force transmission component 120 remains stationary under the action of the fixing pin 173 and the bearing 131.

[0048] The base of the magnetic stand 180 is fixed to the bearing plate 161 or the housing of the air-floating spindle 200 by magnetic means, and the other end is fixed to the displacement sensor 150. The movable joint is adjusted to move the displacement sensor 150 to the protruding end of the spindle rotor 210 close to the air-floating spindle 200, so as to record the axial displacement of the spindle rotor 210 of the air-floating spindle 200 under the action of the axial force.

[0049] In some embodiments, the axial stiffness of the air-bearing main shaft 200 is the ratio of the axial force it bears to the axial displacement.

[0050] It is worth noting that the device 100 of this embodiment can detect the axial stiffness of the air-bearing spindle 200 in a static state (when the air-bearing spindle 200 is not in operation) and a dynamic state (when the air-bearing spindle 200 is in operation).

[0051] Specifically, when the air-floating spindle 200 is in a static state, the force-applying component 110 is twisted to generate an axial force, the force sensor 140 records the value of the axial force, the force transmission component 120 transmits the axial force to the air-floating spindle 200 through the connecting component 130, and the displacement sensor 150 records the axial displacement of the spindle rotor 210 under the action of the axial force, thereby calculating the axial stiffness of the air-floating spindle 200 in a static state.

[0052] When the air-floating spindle 200 is in a dynamic state, due to the action of the bearing 131, the force transmission component 120 is not affected by the rotation of the air-floating spindle 200. The force-applying component 110 is turned to generate an axial force, and the force sensor 140 records the value of the axial force. The force transmission component 120 transmits the axial force to the air-floating spindle 200 through the connecting component 130, and the displacement sensor 150 records the axial displacement of the spindle rotor 210 under the action of the axial force, thereby calculating the axial stiffness of the air-floating spindle 200 in the dynamic state.

[0053] In some embodiments, the device 100 may further include a digital display box, which may be used to display the axial force recorded by the force sensor 140 and the axial displacement recorded by the displacement sensor 150 .

[0054] In the embodiment of the present invention, the force transmission member 120 and the connection member 130 do not need to be disassembled after being assembled, thereby ensuring the measurement accuracy of the axial stiffness of the air-floating spindle 200. When replacing a different type of air-floating spindle 200, it is only necessary to separate the connection plate 134 from the bearing fixing frame 132, connect the connection plate 134 to the new air-floating spindle 200 to be tested according to the reserved holes, and then fix the bearing fixing frame 132 to the connection plate 134.

[0055] In the embodiment of the present invention, the detection work should be carried out on a vibration isolation workbench to reduce the error of displacement detection caused by the tiny vibration generated by the rotation of the air-bearing spindle, thereby reducing the calculation error of the dynamic axial stiffness.

[0056] According to the solution of the present invention, the axial stiffness detection device of the air-floating spindle has a simple and compact structure, a small size, a stable axial force applied, and is easy to control. Only simple tooling is required to conveniently and quickly detect the dynamic axial stiffness of the air-floating spindle, meet the accuracy requirements, and be compatible with a variety of spindles.

[0057] The axial stiffness detection device for the air-floating spindle of the present invention is simple to manufacture, convenient to assemble and replace, greatly reduces the difficulty and cost of detecting the overall dynamic axial stiffness, and is suitable for measuring the overall dynamic axial stiffness of the air-floating spindle in engineering.

[0058] Figure 8 The flowchart of a method 300 for detecting the axial stiffness of an air-bearing spindle according to an embodiment of the present invention is shown. The method 300 is suitable for being implemented by the above-mentioned device 100 for detecting the axial stiffness of an air-bearing spindle.

[0059] like Figure 8 As shown, the method 300 begins with step 302. In step 302, when the air-bearing spindle 200 is in a static state, a first axial force is applied to the air-bearing spindle 200, and a first displacement of the air-bearing spindle 200 in the axial direction is recorded.

[0060] Specifically, the air-floating spindle 200 is fixed on the spindle fixing frame 160 , and the spindle rotor 210 of the air-floating spindle 200 is fixedly connected to the connecting plate 134 .

[0061] The air-floating spindle 200 is kept stationary (i.e., in a static state), an axial force is generated by twisting the force-applying component 110, the magnitude of the first axial force is recorded by the force sensor 140, the first displacement is recorded by the displacement sensor 150, and the axial stiffness of the air-floating spindle 200 in a static state is calculated using the first axial force and the first displacement.

[0062] In some embodiments, before performing step 302, the axial stiffness detection device 100 for the air-bearing spindle is further assembled. Fig. 9 A schematic diagram of the assembly process of an axial stiffness detection device 100 for an air-bearing spindle according to an embodiment of the present invention is shown.

[0063] like Fig. 9 As shown, in the assembly step 402 , the bearing 131 is sleeved into the bearing fixing frame 132 , and the bearing 131 is clamped between the top of the bearing fixing frame 132 and the limiting portion through the limiting portion and the second baffle 135 .

[0064] In the assembly step 404 , the force transmission component 120 is passed through the inner ring of the bearing 131 , and the force transmission component 120 and the bearing 131 are sleeved together using the first baffle 133 .

[0065] In the assembly step 406 , the air-bearing spindle 200 is fixed on the spindle fixing frame 160 , and the connecting plate 134 is fixedly connected to the protruding end of the spindle rotor 210 of the air-bearing spindle 200 .

[0066] In the assembly step 408 , the bearing fixing frame 132 and the connecting plate 134 are fixedly connected.

[0067] In the assembly step 410 , the force applying member 110 is fixed to the force applying member fixing frame 170 , and the force applying member fixing frame 170 is fixedly connected to the spindle fixing frame 160 .

[0068] In the assembly step 412 , the force sensor 140 is arranged between the force applying component 110 and the force transmission component 120 , and the three are sequentially abutted.

[0069] In the assembly step 414 , the bottom of the magnetic base 180 is magnetically attracted to the housing 220 of the air-floating spindle 200 or the example component fixing frame 170 , the displacement sensor 150 is clamped on the magnetic base 180 , and the joint of the magnetic base 180 is adjusted so that the displacement sensor 150 is close to the spindle rotor 210 .

[0070] In this way, the assembly of the device 100 is completed. The device 100 of the present application has a simple and compact structure, a small size, a stable axial force applied, and is easy to control. Only simple tooling is required to conveniently and quickly detect the dynamic axial stiffness of the air-floating spindle 200.

[0071] Subsequently, in step 304, when the air-bearing spindle 200 is in the first dynamic state, a second axial force is applied to the air-bearing spindle 200, and a second displacement of the air-bearing spindle in the axial direction is recorded.

[0072] The air-floating spindle 200 is driven to rotate its spindle rotor 210 at a first speed (i.e., a first dynamic state), an axial force is generated by twisting the force-applying component 110, the magnitude of the second axial force is recorded by the force sensor 140, the second displacement is recorded by the displacement sensor 150, and the axial stiffness of the air-floating spindle 200 in the first dynamic state is calculated using the second axial force and the second displacement.

[0073] When the axial force is transmitted to the air-floating main shaft 200 through the force transmission component 120, the force transmission component 120 does not rotate with the rotation of the air-floating main shaft 200 under the action of the bearing 131, thereby ensuring that when the axial stiffness of the air-floating main shaft 200 is dynamically measured, the rotation of the air-floating main shaft 200 causes the axial force transmitted by the force transmission component 120 to be inaccurate, thereby causing a large deviation in the measurement result.

[0074] Then, in step 306, when the air-bearing spindle 200 is in the second dynamic state, a third axial force is applied to the air-bearing spindle 200, and a third displacement of the air-bearing spindle 200 in the axial direction is recorded, wherein the rotation speed of the air-bearing spindle 200 in the second dynamic state is greater than the rotation speed in the first dynamic state.

[0075] Finally, in step 308, the axial stiffness of the air-floating spindle 200 in different states is calculated using the first axial force, the first displacement, the second axial force, the second displacement, the third axial force, and the third displacement, respectively. Specifically, the axial stiffness of the air-floating spindle 200 is the ratio of the axial force to the axial displacement. For example, in a static state, the axial stiffness of the air-floating spindle 200 is the ratio of the first axial force to the first displacement, in a first dynamic state, the axial stiffness of the air-floating spindle 200 is the ratio of the second axial force to the second displacement, and in a third dynamic state, the axial stiffness of the air-floating spindle 200 is the ratio of the third axial force to the third displacement.

[0076] It should be noted that the working principle and process of the method 300 of this embodiment are similar to those of the above-mentioned device 100. For relevant details, reference may be made to the description of the above-mentioned device 100, which will not be repeated here.

[0077] In the description provided herein, a large number of specific details are described. However, it is understood that embodiments of the present invention can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0078] A10. A device as described in A1, wherein the bearing includes a first sub-bearing and a second sub-bearing, and the first sub-bearing and the second sub-bearing are angular contact ball bearings. A11. A device as described in A10, wherein the first sub-bearing and the second sub-bearing are installed in a back-to-back duplex. B13. A method as described in B12, wherein the axial stiffness of the air-floating main shaft in different states is calculated using the first axial force, the first displacement, the second axial force, the second displacement, the third axial force, and the third displacement, respectively, including: for a target state, the ratio of the axial force to the axial displacement in the target state is used as the axial stiffness of the air-floating main shaft in the target state.

[0079] As used herein, unless otherwise specified, the use of ordinal numbers "first," "second," "third," etc. to describe common objects merely indicates that different instances of similar objects are involved, and is not intended to imply that the objects so described must have a given order in time, space, order, or in any other manner.

[0080] Although the present invention has been described in terms of a limited number of embodiments, it will be apparent to those skilled in the art, having benefit of the above description, that other embodiments are contemplated within the scope of the invention thus described. Furthermore, it should be noted that the language used in this specification is selected primarily for readability and didactic purposes, rather than for the purpose of explaining or defining the subject matter of the present invention. Therefore, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the appended claims.

Claims

1. An axial stiffness detection device for an air-floating spindle, comprising: Force-applying components, force transmission components, connectors, force sensors and displacement sensors; The force-applying member is adapted to generate an axial force; The force sensor is arranged between the force applying component and the force transmitting member, and is suitable for recording the value of the axial force; The force transmission member transmits the axial force to the axial direction of the air-bearing main shaft through the connecting member; The connecting member comprises a bearing, a bearing fixing frame, a first baffle and a connecting plate, wherein the bearing fixing frame is a hollow structure, the bearing is nested in the hollow structure, the bottom of the bearing fixing frame is fixedly connected to the connecting plate, wherein an empty space is formed between the bearing fixing frame, the bearing and the connecting plate; The force transmission component extends into the hollow structure at a side away from the force sensor and is nested in the inner ring of the bearing, and the force transmission component is fixedly connected to the bearing through the first baffle plate, wherein the first baffle plate is in the empty space and does not abut against the bearing fixing frame and the connecting plate; The air-floating main shaft is fixedly connected to the connecting plate, and the displacement sensor is arranged at a position close to the air-floating main shaft, and is suitable for collecting the displacement of the air-floating main shaft in the axial direction under the action of the axial force.

2. The device according to claim 1, wherein: A limiting portion is formed inside the hollow structure of the bearing fixing frame, and the bearing abuts against the limiting portion, so that an empty space is formed between the bearing fixing frame, the bearing and the connecting plate.

3. The device as claimed in claim 2, wherein: The connecting member further includes a second baffle, which is fixedly connected to a side of the hollow structure away from the connecting plate and is suitable for fixing the bearing between the top of the hollow structure and the limiting portion.

4. The device according to claim 1, wherein: Also includes: The spindle fixing frame includes a bearing plate and multiple support plates. The multiple support plates are fixedly connected to the bearing plate. A through hole is formed on the bearing plate, and multiple fixed threaded holes are formed around the through hole. The air-floating spindle partially passes through the through hole, and the air-floating spindle is fixed to the spindle fixing frame through the multiple fixed threaded holes.

5. The device according to claim 1, wherein: The connecting plate is formed with a plurality of connecting threaded holes, through which the connecting plate is fixedly connected to the air-floating main shaft, and any one group of connecting threaded holes is adapted to a model of the air-floating main shaft.

6. The device according to claim 4, wherein: The force applying component is a force applying screw.

7. The device according to claim 6, wherein: Also includes: A force-applying component fixing frame, comprising a mounting plate and a plurality of support columns; One end of each support column is fixed to the bearing plate, and the other end is fixed to the mounting plate; A force-applying threaded hole is formed at the center of the mounting plate, and the force-applying component passes through the force-applying threaded hole and abuts against the force sensor.

8. The device of claim 4, wherein: Also includes: A magnetic table base has one end fixed to the bearing plate or the air-floating spindle housing by magnetic means, and the other end fixed to the displacement sensor.

9. The device of claim 4, wherein: The main shaft fixing frame also includes a rib plate arranged between the supporting plate and the bearing plate.

10. A method for detecting the axial stiffness of an air-bearing spindle, suitable for being implemented by the device according to any one of claims 1 to 9, the method comprising: When the air-floating main shaft is in a static state, applying a first axial force to the air-floating main shaft, and recording a first displacement of the air-floating main shaft in the axial direction; When the air-floating main shaft is in a first dynamic state, applying a second axial force to the air-floating main shaft, and recording a second displacement of the air-floating main shaft in the axial direction; When the air-floating main shaft is in a second dynamic state, a third axial force is applied to the air-floating main shaft, and a third displacement of the air-floating main shaft in the axial direction is recorded, wherein the rotation speed of the air-floating main shaft in the second dynamic state is greater than the rotation speed in the first dynamic state; The axial stiffness of the air-bearing main shaft in different states is calculated using the first axial force, the first displacement, the second axial force, the second displacement, the third axial force, and the third displacement respectively.

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