A lathe spindle limiting head

Abstract

This invention discloses a lathe spindle limiting mandrel, which includes a body with a connecting portion at one end and a spherical protrusion at the other end. An adaptive pad is provided on the surface of the spherical protrusion. The adaptive pad includes a metal mesh skeleton and an elastic body filled within the metal mesh skeleton. When the adaptive pad abuts against the workpiece spindle end face, it undergoes local elastic deformation to adapt to the angular deviation of the workpiece spindle end face. This invention, through the synergistic effect of the spherical protrusion and the adaptive pad, compensates for the perpendicularity deviation between the workpiece end face and the axis during the roughing stage with local elastic deformation, eliminating the clamping bending and machining vibration caused by the non-perpendicularity of the workpiece end face in traditional planar limiting methods.

Description

Technical Field

[0001] This invention relates to the field of machining technology, specifically to a lathe spindle limiting mandrel. Background Technology

[0002] When rough machining shaft-type workpieces such as steering rods on large lathes, to prevent axial movement of the workpiece caused by axial cutting forces, a planar limiting mandrel is usually installed in the taper hole of the lathe spindle. This mandrel acts in opposite directions with the tailstock center of the lathe to clamp the workpiece axially. However, the end face of the workpiece in the rough machining stage is often the blank surface directly formed by the previous process (such as sawing), without any machining. There is a small angle between this plane and the centerline of the workpiece (i.e., the end face is not perpendicular to the axis).

[0003] When the planar limiting mandrel and the tailstock center are clamped together, due to the non-perpendicular nature of the workpiece end face, there is only partial contact between the planar limiting mandrel and the workpiece end face. The contact force deviates from the workpiece axis, generating a bending moment inside the workpiece. Under the action of this bending moment, the workpiece undergoes clamping bending deformation even before cutting begins. As the clamped bending workpiece rotates with the spindle, its centerline deviates from the spindle's rotation center, and the direction of the axial force deviates from the spindle axis, causing the spindle plane bearing to bear additional radial load and produce abnormal noise. After rough machining, the clamping force disappears, and the workpiece elastically recovers under the action of internal stress. The clamping bending deformation is transformed into permanent machining deformation, with workpiece runout reaching 0.25mm to 0.35mm. At the same time, the clamping bending causes uneven force distribution between the lathe chuck end and the tailstock center, and the tailstock center bearing is subjected to uneven load for a long time, accelerating its damage. Summary of the Invention

[0004] This invention provides a lathe spindle limiting mandrel, which overcomes the technical problems in the prior art where the workpiece end face is not perpendicular to the axis during the roughing stage, resulting in clamping bending deformation, reduced machining accuracy, and easy damage to bearings, while the additional end face turning process leads to increased machining costs.

[0005] To achieve the above objectives, the lathe spindle limiting mandrel provided by the present invention includes a body, one end of which is provided with a connecting part for connecting with the lathe spindle, and the other end is provided with a spherical protrusion. The spherical protrusion is used to abut against the end face of the workpiece shaft, and the center of the spherical protrusion is located on the axis of the body.

[0006] Furthermore, it also includes an adaptive pad, which is disposed on the spherical protrusion surface. The adaptive pad includes a metal mesh skeleton and an elastomer filled in the metal mesh skeleton. The adaptive pad is used to generate local elastic deformation when it abuts the end face of the workpiece shaft to adapt to the angular deviation of the end face of the workpiece shaft.

[0007] Furthermore, the metal mesh skeleton is woven from stainless steel wire with a wire diameter of 0.2 mm to 0.8 mm, the mesh size of the metal mesh skeleton is 20 to 60 mesh, the elastomer is silicone rubber with a hardness of Shore A40 to Shore A60, and the volume ratio of the metal mesh skeleton to the silicone rubber is 1:2 to 1:4.

[0008] Furthermore, the adaptive pad is fixed to the spherical raised surface by a flange, the inner edge of the flange is pressed against the edge of the adaptive pad, and the outer edge of the flange is fixedly connected to the body.

[0009] Furthermore, the thickness of the adaptive padding layer is 5mm to 20mm, and the planar compression ratio of the adaptive padding layer is no more than 15%. The test method for the planar compression ratio is as follows: place the adaptive padding layer sample on a universal testing machine, apply pressure to 10MPa at a loading speed of 5mm / min, hold the pressure for 30s, and then measure the thickness. Planar compression ratio = (initial thickness - thickness after holding pressure) / initial thickness × 100%.

[0010] Furthermore, the ratio of the diameter of the spherical protrusion to the diameter of the workpiece shaft end face is 1:1.5 to 1:2.5, and the spherical profile of the adaptive pad is no greater than 0.05mm.

[0011] Furthermore, the permanent deformation of the adaptive pad under a surface pressure of 10 MPa is no more than 0.05 mm. The test method for the permanent deformation is as follows: place the adaptive pad sample on a universal testing machine, apply pressure to 10 MPa at a loading speed of 5 mm / min, hold the pressure for 60 s, unload the load, let it stand for 120 s, and then measure the thickness. The permanent deformation is equal to the initial thickness minus the thickness after unloading.

[0012] Furthermore, the stainless steel wire is made of 304 stainless steel or 316L stainless steel, with a yield strength of not less than 205MPa and an elongation of not less than 40%. The metal mesh skeleton is woven in a twill weave or plain weave pattern, with a wire diameter of 0.3mm to 0.5mm.

[0013] Furthermore, the elastic recovery rate of the metal mesh skeleton under a surface pressure of 10 MPa is not less than 95%.

[0014] Furthermore, the surface hardness of the spherical protrusion is not less than HRC55.

[0015] This invention replaces the traditional planar contact with a spherical protrusion, transforming the local contact force under planar constraint into a concentrated force along the radial direction of the sphere. Since the center of the sphere is located on the main shaft axis, the direction of the contact force coincides with the main shaft axis, eliminating the bending moment caused by the workpiece end face not being perpendicular to the axis, and avoiding clamping bending deformation.

[0016] This invention adds an adaptive pad layer composed of a metal mesh skeleton and silicone rubber to the spherical raised surface. The metal mesh skeleton provides sufficient axial stiffness to transmit the thrust force, and the silicone rubber undergoes elastic deformation when locally compressed, so that the surface of the pad layer and the end face of the workpiece form a surface contact rather than a point contact, dispersing the concentrated force into a distributed force. As a result, the rudder stick runout is reduced from 0.25mm~0.35mm to 0.05mm~0.07mm, and the tailstock bearing operates normally. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the assembly structure of a workpiece in the prior art.

[0018] Figure 2 This is a schematic diagram of the top head structure shown in this invention.

[0019] Figure 3 This is a schematic diagram of the internal structure of the top head shown in this invention.

[0020] Reference numerals: 1 Body, 2 Spherical protrusion, 3 Metal mesh skeleton, 4 Elastomer, 5 Flange. Detailed Implementation

[0021] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It is to be understood that the specific embodiments described herein are merely illustrative of this application and not intended to limit it. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0022] The terms “comprising” and “having”, and any variations thereof, used in this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0023] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly or implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0024] Figures 1 to 3 A schematic structural diagram of a lathe spindle limiting mandrel according to an embodiment of the present invention is shown. Figures 1 to 3As shown, the present invention provides a lathe spindle limiting mandrel, which is mainly used for axial positioning and limiting of shaft-type workpieces such as rudder shafts, tail shafts, and intermediate shafts during the rough machining stage of large lathes.

[0025] The lathe spindle limiting mandrel of the present invention mainly includes a body 1, a spherical protrusion 2, and an adaptive pad layer disposed on the surface of the spherical protrusion 2. One end of the body 1 is provided with a connecting part for engaging with the tapered hole of the lathe spindle. The connecting part is a Morse taper shank, the taper of which is adapted to the taper of the lathe spindle tapered hole (Mohs taper 6 or 7), used to fix the mandrel to the end of the lathe spindle. The other end of the body 1 is provided with the spherical protrusion 2, which abuts against the end face of the workpiece shaft. The center of the spherical protrusion 2 is located on the axis of the body 1, that is, the rotation center of the spherical protrusion 2 coincides with the rotation axis of the lathe spindle.

[0026] An adaptive pad is disposed on the surface of the spherical protrusion 2. The adaptive pad includes a metal mesh skeleton 3 and an elastomer 4 filled within the metal mesh skeleton 3. The metal mesh skeleton 3 is a mesh structure woven from stainless steel wire, and its function is to provide the overall structural strength and axial stiffness of the adaptive pad, ensuring that the pad will not undergo overall crushing or plastic collapse under an axial thrust of 150 to 200 tons. The stainless steel wire is made of 304 stainless steel or 316L stainless steel, with a yield strength of not less than 205 MPa and an elongation of not less than 40%. The yield strength of 304 stainless steel is approximately 205 MPa to 215 MPa, and the yield strength of 316L stainless steel is approximately 170 MPa to 200 MPa. Both have excellent corrosion resistance and toughness, and their elongation is above 40%, making them less prone to fatigue fracture under repeated axial loading.

[0027] The metal mesh skeleton 3 is woven using either twill or plain weave. Plain weave provides a stable mesh structure and high compressive strength, making it suitable for applications with high axial loads. Twill weave offers better flexibility and extensibility, making it suitable for applications with larger workpiece end-face deviations and higher requirements for adaptive bonding. The wire diameter of the metal mesh skeleton 3 is 0.2mm to 0.8mm, preferably 0.3mm to 0.5mm. If the wire diameter is too thin, the skeleton's axial stiffness is insufficient, making it prone to crushing under jacking force; if the wire diameter is too thick, the skeleton loses its elastic deformation capacity, failing to achieve adaptive bonding. The mesh count of the metal mesh skeleton 3 is 20 to 60 meshes, preferably 30 to 50 meshes. If the mesh count is too low, the mesh openings are too large, and the silicone rubber is easily squeezed into the mesh and extruded under pressure, resulting in an uneven surface of the pad; if the mesh count is too high, the mesh openings are too small, resulting in insufficient silicone rubber filling and limited elastic deformation capacity of the pad.

[0028] Elastomer 4 fills the mesh openings and surface of the metal mesh skeleton 3. Elastomer 4 is silicone rubber with a Shore A40 to Shore A60 hardness. Silicone rubber possesses excellent elasticity, heat resistance, and aging resistance. Under rough machining conditions, the ambient temperature is typically 20°C to 50°C, but due to cutting heat conduction, the temperature at the mandrel tip may rise to 80°C to 120°C. Silicone rubber maintains stable elasticity and mechanical properties. The Shore A40 to Shore A60 hardness range of the silicone rubber was determined experimentally. When the hardness is below Shore A40, the silicone rubber is too soft and prone to excessive compression under axial thrust, resulting in a planar compression ratio of the self-adaptive pad exceeding 15%, causing the mandrel to lose its axial limiting function. When the hardness is above Shore A60, the silicone rubber is too hard and cannot generate sufficient local elastic deformation when there is an angular deviation on the workpiece end face, leading to decreased self-adaptive bonding ability and insufficient improvement in contact stress concentration.

[0029] The volume ratio of the metal mesh skeleton 3 to the silicone rubber is 1:2 to 1:4, meaning the metal mesh skeleton accounts for 20% to 33% of the total volume of the adaptive padding layer, and the silicone rubber accounts for 67% to 80%. When the proportion of the metal mesh skeleton is less than 1:4, the axial stiffness of the skeleton is insufficient, and the padding layer is excessively compressed under jacking. When the proportion of the metal mesh skeleton is greater than 1:2, the mesh of the skeleton is too dense, the filling space of the silicone rubber is insufficient, and the elastic deformation capacity of the padding layer is limited.

[0030] The adaptive pad is fixed to the surface of the spherical protrusion 2 by flange 5. Flange 5 is an annular component, with its inner edge pressed against the edge of the adaptive pad, and its outer edge fixedly connected to the body 1 by bolts or welding. The fixing method of flange 5 securely restrains the adaptive pad to the surface of the spherical protrusion 2, preventing the pad from slipping or falling off during the jacking process; on the other hand, the inner edge of flange 5 only presses against the edge area of ​​the adaptive pad, while the central area of ​​the adaptive pad is not restrained by flange 5, thus retaining the ability to deform freely.

[0031] The thickness of the adaptive pad is 5mm to 20mm. When the thickness is less than 5mm, the elastic deformation capacity of the pad is insufficient and cannot effectively compensate for the angular deviation of the workpiece end face; when the thickness is greater than 20mm, the axial stiffness of the pad is reduced, and the compression under the thrust is too large, affecting the limiting accuracy and the stability of axial positioning.

[0032] The spherical profile of the adaptive pad should not exceed 0.05 mm. Spherical profile refers to the deviation of the adaptive pad surface from the theoretical sphere. This requirement ensures that the adaptive pad maintains its spherical shape after installation, avoiding additional contact unevenness caused by the shape deviation of the pad itself.

[0033] The ratio of the diameter of the spherical protrusion 2 to the diameter of the workpiece shaft end face is 1:1.5 to 1:2.5, meaning the diameter of the spherical protrusion 2 is smaller than the diameter of the workpiece shaft end face. If the diameter is too small, the curvature of the spherical surface is too large, and the contact area is too concentrated near the apex of the spherical surface, resulting in concentrated contact stress and making it easy to generate indentations on the workpiece end face. If the diameter is too large, the curvature of the spherical surface is too small, and the spherical surface tends to be flat, reducing the ability to adapt to angular deviations and weakening the advantages of spherical contact.

[0034] The surface hardness of the spherical protrusion 2 is not less than HRC55, and the surface is hardened to ensure that the spherical protrusion 2 itself does not wear or deform under frequent axial impact and friction conditions.

[0035] The technical effects of the present invention will be described in detail below through specific embodiments and comparative examples.

[0036] Example 1 A rough machining test of the rudder stock was conducted on a lathe. The rudder stock was made of Q345E low-alloy high-strength steel, with a diameter of 280 mm and a shaft end face diameter of 250 mm. The perpendicularity deviation between the shaft end face and the axis was approximately 0.8°. The limiting mandrel of this invention was installed in the lathe spindle taper hole. The spherical protrusion 2 had a ball diameter of 150 mm (the ratio of ball diameter to end face diameter was 1:1.67), the thickness of the self-adaptive pad was 12 mm, the metal mesh skeleton 3 was made of 316L stainless steel with a wire diameter of 0.4 mm, a twill weave, a mesh count of 40, and a silicone rubber hardness of Shore A50. The volume ratio of the metal mesh skeleton to the silicone rubber was 1:3. After installation, the lathe was started, the spindle speed was 120 r / min, and the thrust was 160 tons.

[0037] During the rough machining process, the lathe spindle box produced no abnormal noise, and the machining process was smooth. After the rough machining was completed, the runout of the rudder stick was re-measured, and the runout was 0.06 mm. The tailstock center bearing was inspected after machining 10 rudder sticks consecutively, and the bearing was in good condition with no obvious wear.

[0038] Example 2 Under the same operating conditions, comparative tests were conducted by varying only the thickness of the adaptive pad. When the adaptive pad thickness was 5mm, the rudder stick runout after rough machining was 0.08mm, which is better than the traditional planar limit, but slightly thicker than in Example 1. When the adaptive pad thickness was 20mm, the rudder stick runout after rough machining was 0.09mm. This was because the excessive pad thickness reduced the axial stiffness, resulting in additional compression during the jacking process.

[0039] Example 3 Under the same operating conditions, a comparative experiment was conducted by changing only the volume ratio of the metal mesh skeleton 3 to the silicone rubber. When the volume ratio was 1:1, the silicone rubber filling was insufficient, the elastic deformation capacity of the padding layer was poor, and the rudder stick runout after rough machining was 0.15mm, failing to fully utilize the adaptive bonding effect. When the volume ratio was 1:5, the axial stiffness of the skeleton was insufficient, the padding layer was excessively compressed during the pushing process, the limiting accuracy decreased, and the rudder stick runout was 0.18mm.

[0040] Example 4 Under the same operating conditions, a comparative test was conducted by varying only the spherical profile of the adaptive pad. When the spherical profile was 0.03 mm, the surface shape accuracy of the pad was high, the adaptive bonding effect was good, and the rudder stock runout was 0.05 mm. When the spherical profile was 0.05 mm, the rudder stock runout was 0.06 mm, still within an acceptable range. When the spherical profile exceeded 0.05 mm, the shape deviation of the pad itself led to uneven contact, and the rudder stock runout increased to 0.11 mm. The test results show that a spherical profile of no more than 0.05 mm can ensure the effective operation of the adaptive pad.

[0041] Example 5 Under the same working conditions, a comparative experiment was conducted by changing only the ratio of the spherical diameter of the spherical protrusion 2 to the diameter of the workpiece shaft end face. When the ratio of the spherical diameter to the end face diameter was 1:1.5, the spherical curvature was moderate, the rudder stick runout was 0.05 mm, and there were no visible indentations on the workpiece end face. When the ratio was 1:2.5, the spherical curvature was relatively large, the rudder stick runout was 0.07 mm, and a slight indentation appeared on the end face, but it was still within an acceptable range. When the ratio was 1:3, the spherical curvature was too large, the contact stress was concentrated, and a significant indentation appeared on the end face with a depth of about 0.15 mm, affecting the surface quality of the workpiece in subsequent processing and use. When the ratio was 1:1.2, the spherical surface approached a plane, the adaptive angle deviation capability decreased, and the rudder stick runout after rough machining was 0.13 mm. The experimental results show that the spherical diameter ratio range of 1:1.5 to 1:2.5 ensures a balance between adaptive capability and contact stress.

[0042] Comparative Example 1 A rough machining test of the rudder stock was conducted using a traditional planar limiting mandrel under identical working conditions. The end face of the planar limiting mandrel is flat and directly abuts against the end face of the workpiece shaft. Due to a 0.8° perpendicularity deviation between the workpiece shaft end face and the axis, the contact between the planar limiting mandrel and the end face is partial. During rough machining, the lathe spindle box continuously emitted a "bang" noise. After rough machining, the measured runout of the rudder stock was 0.32 mm, exceeding the design requirement (runout not greater than 0.10 mm). Inspection of the tailstock center bearing revealed significant fatigue spalling and wear, necessitating replacement. The test results are completely consistent with the problem described in the background art, proving the failure of the traditional planar limiting mandrel under conditions where the workpiece end face is not perpendicular.

[0043] Comparative Example 2 A mandrel using a spherical protrusion 2 without an adaptive pad was tested under the same working conditions. The spherical protrusion 2 in this comparative example is a pure metal sphere with a diameter of 150mm. No abnormal noise was observed in the spindle box during rough machining. After rough machining, the rudder stick runout was measured at 0.18mm. Although better than traditional planar limiting, it still did not meet the design requirements. Inspection of the workpiece shaft end face revealed obvious indentations in the spherical contact area, with a depth of approximately 0.08mm. Comparative Example 2 illustrates that although the pure spherical mandrel eliminates the bending moment, the contact between the sphere and the end face is point contact, with contact stress concentrated near the apex of the sphere. Under a 160-ton thrust, this resulted in a significant localized plastic indentation, and the high localized stress led to considerable elastic deformation of the workpiece, preventing the runout from being fully controlled within the design range.

[0044] Comparative Example 3 A test was conducted under the same working conditions on a mandrel employing an adaptive pad but with a wire diameter in the metal mesh skeleton 3 exceeding the range of this invention. In this comparative example, the wire diameter was 1.2 mm, and other parameters of the adaptive pad were the same as in Example 1. Due to the excessively thick wire diameter, the flexibility of the metal mesh skeleton 3 was significantly reduced, and the adaptive pad could not generate sufficient local elastic deformation to compensate for the end face angle deviation when it abutted against the workpiece shaft end face. After rough machining, the measured runout of the rudder stick was 0.22 mm, which was similar to that of Comparative Example 2 without an adaptive pad, and the indentation depth on the workpiece end face was 0.06 mm. The test results show that when the wire diameter exceeds the range of 0.2 mm to 0.8 mm, the elastic deformation capability of the metal mesh skeleton 3 is severely reduced, and the function of the adaptive pad cannot be realized.

[0045] Comparative Example 4 A mandrel employing an adaptive pad but with silicone rubber hardness exceeding the range of this invention was tested under the same working conditions. In this comparative example, the silicone rubber hardness was Shore A80, and other parameters of the adaptive pad were the same as in Example 1. Excessive silicone rubber hardness limited the elastic deformation capacity of the adaptive pad, preventing it from fully adhering to the workpiece end-face angle deviation, resulting in localized contact stress concentration. After rough machining, the rudder stick runout was measured to be 0.21 mm, and the workpiece end-face indentation depth was 0.07 mm. The test results indicate that when the silicone rubber hardness exceeds the Shore A40 to A60 range, the elastic deformation capacity of the adaptive pad decreases, failing to effectively compensate for end-face angle deviations.

[0046] Comparative Example 5 A test was conducted under the same working conditions on a mandrel employing an adaptive padding layer but with a volume ratio of metal mesh skeleton 3 to silicone rubber exceeding the scope of this invention. In this comparative example, the volume ratio is 1:1 (metal mesh skeleton 3 accounts for 50%), and other parameters of the adaptive padding layer are the same as in Example 1. Insufficient silicone rubber filling limits elastic deformation capacity and results in poor adaptive bonding. The rudder stock runout measured after rough machining is 0.23 mm.

[0047] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A lathe spindle limiting mandrel, characterized in that, include: The body (1) has a connecting part at one end for connecting with the lathe spindle, and a spherical protrusion (2) at the other end. The spherical protrusion (2) is used to abut against the end face of the workpiece shaft, and the center of the spherical protrusion (2) is located on the axis of the body (1).

2. The lathe spindle limiting mandrel according to claim 1, characterized in that, It also includes an adaptive pad layer disposed on the surface of the spherical protrusion (2). The adaptive pad layer includes a metal mesh skeleton (3) and an elastomer (4) filled in the metal mesh skeleton (3). The adaptive pad layer is used to generate local elastic deformation when abutting the end face of the workpiece shaft to adapt to the angular deviation of the end face of the workpiece shaft.

3. The lathe spindle limiting mandrel according to claim 2, characterized in that, The metal mesh skeleton (3) is woven from stainless steel wire with a wire diameter of 0.2 mm to 0.8 mm. The mesh size of the metal mesh skeleton (3) is 20 to 60 meshes. The elastomer (4) is silicone rubber with a Shore A40 to Shore A60 hardness. The volume ratio of the metal mesh skeleton (3) to the silicone rubber is 1:2 to 1:

4.

4. The lathe spindle limiting mandrel according to claim 2, characterized in that, The adaptive pad is fixed to the surface of the spherical protrusion (2) by a flange (5), the inner edge of the flange (5) is pressed against the edge of the adaptive pad, and the outer edge of the flange (5) is fixedly connected to the body (1).

5. The lathe spindle limiting mandrel according to claim 2, characterized in that, The thickness of the adaptive padding layer is 5 mm to 20 mm, and the planar compression ratio of the adaptive padding layer is not greater than 15%. The test method for the planar compression ratio includes: placing the adaptive padding layer sample on a universal testing machine, applying pressure to 10 MPa at a loading speed of 5 mm / min, holding the pressure for 30 s, and then measuring the thickness. The planar compression ratio is calculated as (initial thickness - thickness after holding pressure) / initial thickness × 100%.

6. The lathe spindle limiting mandrel according to claim 2, characterized in that, The ratio of the spherical diameter of the spherical protrusion (2) to the diameter of the workpiece shaft end face is 1:1.5 to 1:2.5, and the spherical profile of the adaptive pad is not greater than 0.05 mm.

7. The lathe spindle limiting mandrel according to claim 2, characterized in that, The permanent deformation of the adaptive pad under a surface pressure of 10 MPa is no more than 0.05 mm. The test method for the permanent deformation includes: placing the adaptive pad sample on a universal testing machine, applying pressure to 10 MPa at a loading speed of 5 mm / min, holding the pressure for 60 s and then unloading the load, letting it stand for 120 s and then measuring the thickness. The permanent deformation is calculated as: initial thickness - thickness after unloading.

8. The lathe spindle limiting mandrel according to claim 3, characterized in that, The stainless steel wire is made of 304 stainless steel or 316L stainless steel, with a yield strength of not less than 205MPa and an elongation of not less than 40%. The metal mesh skeleton (3) is woven in a twill weave or a plain weave, with a wire diameter of 0.3mm to 0.5mm.

9. The lathe spindle limiting mandrel according to claim 2, characterized in that, The elastic recovery rate of the metal mesh skeleton (3) under 10MPa surface pressure is not less than 95%.

10. The lathe spindle limiting mandrel according to claim 1, characterized in that, The surface hardness of the spherical protrusion (2) is not less than HRC55.

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