An external thread grinder for planetary roller screws and a design method

Abstract

This invention relates to the field of thread processing machine tool technology, and particularly to a planetary roller screw external thread grinding machine and its design method. The structure of the planetary roller screw external thread grinding machine includes a grinding machine body with perpendicularly intersecting screw and grinding wheel tracks; a screw fixing module disposed on the screw track; a grinding wheel grinding module disposed on the grinding wheel track, comprising a rotary table, a grinding wheel assembly, and a dressing assembly; a precision monitoring module including a grating ruler assembly, an acoustic emission sensor, a dynamic balancing instrument, a six-axis force sensor, and a probe assembly, with the grating ruler assembly disposed on the grinding machine body, the acoustic emission sensor and dynamic balancing instrument disposed on the grinding wheel module, and the probe assembly disposed on the rotary table; and a control system connected to the precision monitoring module. This planetary roller screw external thread grinding machine and its design method can solve the problem of insufficient machining accuracy caused by the lack of detection and compensation mechanisms in existing external thread grinding machines.

Description

Technical Field

[0001] This application relates to the field of thread processing machine tool technology, and in particular to an external thread grinding machine for planetary roller screws and its design method. Background Technology

[0002] Planetary roller screws are core transmission components in high-end equipment such as aerospace and semiconductor lithography machines. They are widely used due to their advantages of high transmission accuracy, large load capacity and long service life. Their external thread processing needs to meet micron-level accuracy requirements and have the structural characteristics of multi-start threads and long processing stroke. Therefore, extremely high requirements are placed on the accuracy, intelligence and specialization of external thread grinding machines.

[0003] Traditional external thread grinding machines have the following shortcomings when machining planetary roller screws: First, during long-stroke machining, grinding heat and ambient temperature rise cause axial elongation of the screw. Traditional tailstock centers can only achieve simple extension and retraction, and cannot accurately calculate the relationship between thermal expansion and axial stress, which easily causes micro-bending of the screw under pressure, affecting coaxiality. Second, the center rest uses a metal hard-contact clamping method, which can easily scratch the machined threads during long-stroke movement, and has poor clamping follow-up and insufficient centering accuracy. Third, there is a lack of real-time detection and dynamic compensation for grinding wheel wear, and the grinding wheel profile deviates due to wear, resulting in a decrease in machining accuracy. Fourth, the traditional linear motor arrangement lacks an effective heat insulation and cooling structure, and the motor heat can easily cause thermal deformation of the mineral casting bed, leading to transmission positioning errors. Fifth, it is difficult to accurately detect and compensate for pitch and indexing errors in multi-start thread machining. Traditional probes can only achieve simple dimensional detection and lack a systematic error mathematical model, thus failing to guarantee the machining consistency of multi-start threads.

[0004] In addition, existing design methods for external thread grinding machines focus more on component selection and functional implementation, lacking quantitative design models and closed-loop compensation mechanisms for the characteristics of planetary roller screw machining, making it difficult to meet micron-level machining requirements. Summary of the Invention

[0005] In view of this, the purpose of this application is to provide an external thread grinding machine for planetary roller screws and a design method to solve the problem that existing external thread grinding machines lack detection and compensation mechanisms, resulting in insufficient machining accuracy.

[0006] According to a first aspect of the present invention, an external thread grinding machine for planetary roller screws is provided, wherein the external thread grinding machine for planetary roller screws comprises: a grinding machine body, having a screw slide and a grinding wheel slide that intersect perpendicularly, the screw slide extending along a linear axis Z-axis, and the grinding wheel slide extending along a linear axis X-axis; a screw fixing module movably disposed on the screw slide, a workpiece being fixed to the screw fixing module, the screw fixing module being capable of driving the workpiece to rotate about a rotation axis C-axis; and a grinding wheel grinding module movably disposed on the grinding wheel slide, the grinding wheel grinding module including a rotary table, a grinding wheel assembly, and a dressing assembly. The rotary table can drive the grinding wheel assembly and the dressing assembly to rotate around the rotation axis A. The dressing assembly is adjustablely positioned on the upper part of the grinding wheel assembly. The precision monitoring module includes a grating ruler assembly, an acoustic emission sensor, a dynamic balancing instrument, a six-axis force sensor, and a probe assembly. The grating ruler assembly is located on the grinding machine body. The acoustic emission sensor and the dynamic balancing instrument are located on the grinding wheel grinding module. The probe assembly is located on the rotary table. The probe assembly includes a probe part that is oscillatingly positioned on the side of the grinding wheel assembly. The system is connected to the precision monitoring module.

[0007] Preferably, the dressing assembly includes a dressing shaft, a dressing wheel, and a cross slide assembly. The cross slide assembly includes a first slide and a second slide arranged perpendicularly to each other. The first slide extends along a linear axis Y-axis, and the second slide extends along a linear axis W-axis. The second slide is slidably disposed on the first slide. The dressing shaft is slidably disposed on the second slide. The dressing wheel is disposed at the end of the dressing shaft. The dressing wheel adjusts its contact position with the grinding wheel assembly via the cross slide assembly to dress the grinding wheel assembly. The grinding wheel assembly includes a grinding wheel body and a grinding wheel shaft. The grinding wheel body is disposed on the cross slide assembly. The grinding wheel spindle drives the grinding wheel body to rotate. The dynamic balancing instrument is located inside the grinding wheel spindle, and the acoustic emission sensor is located on the upper part of the grinding wheel spindle. The probe assembly also includes a transmission part, which is mounted on the turntable via a mounting plate. The first end of the probe part is a detection end, and the second end of the probe part is pivotally connected to the transmission part. When the planetary roller screw external thread grinding machine is working, the grinding wheel body processes the workpiece, the dressing wheel contacts the grinding wheel body, and after the workpiece is processed, the detection end of the probe part contacts the external thread of the workpiece.

[0008] Preferably, the lead screw fixing module includes a worktable, a head clamping frame, a tail clamping frame, and at least one set of center frames. The head clamping frame, the tail clamping frame, and the center frames are all slidably mounted on the worktable via sliding seats. The rotation axis of the head clamping frame is the C-axis. The head clamping frame is positioned by a torque motor in conjunction with a circular grating. The tail clamping frame is a constant force adaptive thermal compensation tailstock. The six-axis force sensor is integrated into the tail clamping frame. The center frame includes a positioning body, a first pressure rod, a second pressure rod, and a third pressure rod. The first pressure rod, the second pressure rod, and the third pressure rod are sequentially arranged vertically on the positioning body. The first pressure rod and the third pressure rod each include an arc-shaped clamping part, a first pushing part, and a first fixing part. One end of the arc-shaped clamping part extends out of the positioning body, and the other end of the arc-shaped clamping part is arbitrarily connected to the positioning body via the first pushing part. The first fixing part passes through the arc-shaped clamping part and the center frame. The positioning body includes symmetrically arranged arc-shaped clamping portions of the first and third pressure rods to clamp planetary roller screws respectively; the second pressure rod includes an abutment portion, a second pushing portion, and a second fixing portion, one end of the abutment portion passes through the positioning body to abut the planetary roller screw, the other end of the abutment portion is connected to the second pushing portion, and the second fixing portion passes through the abutment portion and the positioning body; the arc-shaped clamping portions of the first and third pressure rods, the abutment portion, and the third pressure rod form a three-contact fixed-circle clamping structure around the workpiece to be processed; the grinding wheel module also includes a grinding wheel slide plate and a grinding wheel pad plate disposed at the bottom of the turntable, the turntable is connected to the grinding wheel slide plate through the grinding wheel pad plate, and the grinding wheel slide plate is slidably connected to the grinding wheel slide; the grating ruler assembly includes a first grating ruler and a second grating ruler, the first grating ruler is disposed on the side of the worktable, and the second grating ruler is disposed on the side of the grinding wheel slide plate.

[0009] Preferably, both the lead screw slide and the grinding wheel slide are provided with U-shaped grooves, and a slide rail body is provided inside the U-shaped grooves. Limiting components are provided at both ends of the slide rail body. Both the lead screw slide and the grinding wheel slide are equipped with a linear motor direct drive system. The linear motor direct drive system includes a linear motor and a magnetic plate. The linear motor is used to drive the lead screw fixing module and the grinding wheel grinding module. The magnetic plate is laid on the lead screw slide and the grinding wheel slide.

[0010] According to a second aspect of the present invention, a design method for a planetary roller screw external thread grinding machine is provided. The design method is used to design the planetary roller screw external thread grinding machine as described above. The design method includes: a thermally symmetrical and constant-force thermal compensation structure design for long-stroke machining; a flexible adaptive clamping design for the center rest; a grinding-repair collaborative dynamic compensation structure design based on acoustic emission monitoring; a thermal insulation and cooling structure design for the linear motor direct-drive system; and a design for in-situ detection of the probe section and indexing error modeling and path compensation for multi-start threads.

[0011] Preferably, the tail clamping frame is equipped with a retractable tip and a hydraulic telescopic mechanism. The retractable tip is connected to the tail clamping frame via the hydraulic telescopic mechanism. The six-axis force sensor is integrated at the end of the retractable tip and is signal-connected to the hydraulic telescopic mechanism and the control system. The control system calculates the axial elongation using a lead screw thermal expansion calculation model and adjusts the tip retraction amount ΔS in real time using an axial stress-retraction correlation model to maintain a constant clamping force. The thermal symmetry and constant force thermal compensation structure design for long-stroke machining includes the following steps: calculating the axial elongation of the lead screw under different temperature rises using the lead screw thermal expansion calculation model, and designing the retractable tip as a hydraulic... The system employs a drive elastic structure with an axial allowance matching the elongation. A six-axis force sensor is integrated at the end of the retractable tip. A first temperature sensor is attached to the workpiece. The first temperature sensor and the six-axis force sensor are connected to the control system signals. A quantitative relationship between stress and tip retraction is established using the axial stress-retraction correlation model. A constant clamping force adaptive adjustment program is written into the control system, with a preset clamping force threshold. Based on the detection data and the axial stress-retraction correlation model, the tip retraction is calculated and adjusted in real time. The head clamping frame adopts a fixed-axis rotation design, forming a thermally symmetrical structure between the retractable tips of the head clamping frame and the tail clamping frame.

[0012] Preferably, the center frame is a hydrostatic follower-type center frame, which is equipped with a hydrostatic support system. Oil holes are formed on the clamping surfaces of the arc-shaped clamping part and the abutment part. The hydrostatic support system includes an oil passage, which communicates with the oil holes to form an oil film of 5μm to 10μm. The center frame achieves non-contact flexible clamping based on a hydrostatic oil film pressure model and an oil film gap-clamping force correlation model. The flexible adaptive clamping design of the center frame includes the following steps: calculating the target oil film gap and oil supply pressure corresponding to different nominal screw diameters using the hydrostatic oil film pressure model and the oil film gap-clamping force correlation model, and determining the core design parameters of the center frame clamping structure; based on the three-contact fixed-circle clamping structure... Based on this, the arc-shaped clamping part is made of engineering ceramic material, and oil holes are opened on the clamping surfaces of the arc-shaped clamping part and the abutment part. A hydrostatic support system including an oil pump, oil circuit and pressure sensor is configured. The sliding mating surface between the center frame and the worktable is designed as a hydrostatic guide rail structure. The pressure sensor is connected to the control system signal. The quantitative relationship between oil supply pressure and clamping force is established through the oil film gap-clamping force correlation model. The clamping force threshold of a single clamping part is preset. An oil film pressure adaptive adjustment program is written into the control system. Based on the detection data of the pressure sensor and the oil film gap-clamping force correlation model, the oil supply pressure of the oil pump is adjusted in real time to ensure that the oil film gap is stable between 5μm and 10μm.

[0013] Preferably, the planetary roller screw external thread grinding machine is equipped with a grinding and repair collaborative dynamic compensation system. The grinding and repair collaborative dynamic compensation system includes a grinding wheel wear signal feature library and a cross slide assembly drive system. The acoustic emission sensor is signal-connected to the control system and the cross slide assembly drive system. The control system extracts feature values ​​through the acoustic emission signal effective value formula and stores them in the grinding wheel wear signal feature library. It also calculates the real-time wear amount based on the acoustic emission-grinding wheel wear amount fitting model and drives the cross slide assembly to feed. The design of the grinding and dressing collaborative dynamic compensation structure based on acoustic emission monitoring includes the following steps: integrating the acoustic emission sensor on the upper part of the grinding wheel shaft, so that the acoustic emission sensor forms a closed-loop signal connection with the control system and the cross slide assembly drive system, so as to collect acoustic emission signals in real time, extract feature values ​​through the effective value formula, and store them in the grinding wheel wear signal feature library; obtaining the feature values ​​of grinding wheel acoustic emission signals and actual wear amount under different wear states through preliminary experiments, establishing an acoustic emission-grinding wheel wear amount fitting model using a univariate linear fitting algorithm, and inputting it into the control system; designing a cross slide feed linkage program, in which the control system calculates the real-time wear amount of the grinding wheel body according to the real-time detected feature values ​​through the acoustic emission-grinding wheel wear amount fitting model, and drives the cross slide assembly to make feed adjustments according to the feed amount formula; realizing closed-loop control of acoustic emission monitoring-wear amount calculation-feed dressing, ensuring that the dressing amount of the dressing wheel is accurately matched with the grinding consumption of the grinding wheel body.

[0014] Preferably, the linear motor direct drive system is provided with the heat insulation and cooling structure, which includes a heat insulation pad, cooling channels, thermally isolated connectors, and a heat insulation protective cover. The heat insulation pad is located between the U-shaped groove and the magnetic plate, and the cooling channels are located on both sides of the U-shaped groove. The mover of the linear motor and the moving parts are connected by the thermally isolated connectors. The heat insulation protective cover is installed on the grating ruler assembly. The stator of the linear motor is provided with a second temperature sensor, which is connected to the control system. The control system realizes quantitative control of thermal deformation through the thermal deformation calculation model and the heat dissipation power calculation model of the linear motor, ensuring that the stator temperature rise of the linear motor is ≤5℃. The heat insulation and cooling structure design of the linear motor direct drive system includes the following steps: calculating the stator thermal deformation of the linear motor under different temperature rises through the thermal deformation calculation model, and... The heat dissipation power calculation model is used to determine the heat dissipation power requirements of the heat insulation and cooling structure, and to define the structural design standards for heat insulation, cooling, and thermal isolation. A heat insulation pad is placed between the U-shaped groove and the magnetic plate. Cooling channels extending along the length of the slide are opened on both sides of the U-shaped groove and connected to the water cooling system. A thermally isolated connector is installed between the mover and moving parts of the linear motor. A heat insulation protective cover is added to the grating ruler assembly. The second temperature sensor is attached to the stator of the linear motor, and the second temperature sensor is connected to the water cooling system through the control system signal, establishing a quantitative relationship between motor temperature rise and coolant flow rate. A thermal deformation adaptive adjustment program is written into the control system. Based on the detection data of the second temperature sensor and the thermal deformation calculation model, the coolant flow rate of the water cooling system is adjusted in real time to ensure that the stator temperature rise of the linear motor is ≤5℃.

[0015] Preferably, the planetary roller screw external thread grinding machine is equipped with a multi-start thread detection and compensation system. The multi-start thread detection and compensation system includes an error mathematical model. The probe part of the probe assembly is connected to the torque motor and the first optical grating. The detection path of the probe part follows the parametric equation of the planetary roller screw helical trajectory. The control system uses a least-squares fitting algorithm to establish the error mathematical model and performs reverse compensation for the C-axis and Z-axis. The error mathematical model includes the indexing error of the C-axis, the feed error of the Z-axis, and the helix angle error. The multi-start thread detection and compensation system realizes pre-compensation and real-time compensation of machining errors. The in-situ detection of the probe part and the modeling and path compensation design of the multi-start thread indexing error include the following steps: connecting the probe assembly, the torque motor, and the first optical grating. The grating ruler signal is connected, the basic parameters of the workpiece to be processed are set, and the detection path of the probe part is planned by the helical trajectory formula. Taking the end face of the lead screw blank as the reference, the micron-level precise positioning of the starting point of the multi-start thread is achieved by the angular indexing of the C-axis and the axial positioning of the Z-axis, and the coordinates of each starting point are recorded. After single-start thread grinding, the probe part is made to detect along the helical trajectory and extract the pitch and indexing error data. The least squares fitting algorithm is used to establish the error mathematical model of multi-start thread processing, which includes the indexing error of the C-axis, the feed error of the Z-axis, and the helix angle error. The linkage path compensation program is designed to calculate the compensation amount in real time based on the error mathematical model, and to perform pre-compensation and real-time compensation for subsequent thread head processing. After the full stroke processing, the probe part is used for re-inspection and secondary path adjustment.

[0016] The planetary roller screw external thread grinding machine and its design method according to embodiments of the present invention feature a precision monitoring module that monitors the working data of the screw fixing module and the grinding wheel module in real time. The control system applies a quantitative mathematical model based on the collected data to achieve quantitative design and closed-loop compensation. This enables thermal symmetry and constant force thermal compensation for long-stroke machining, hydrostatic following flexible adaptive clamping of the center rest, collaborative dynamic compensation for grinding based on acoustic emission monitoring, thermal insulation and cooling structure design of the linear motor direct drive system, and in-situ probe detection and multi-start thread indexing error modeling and path compensation. This effectively solves the problem of insufficient machining accuracy caused by the lack of detection and compensation mechanisms in existing external thread grinding machines.

[0017] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A schematic diagram of the structure of an external thread grinding machine for planetary roller screws according to an embodiment of the present invention is shown; Figure 2 A schematic diagram of the structure of a grinding wheel module according to an embodiment of the present invention is shown; Figure 3 A schematic diagram of the grinding wheel module according to an embodiment of the present invention is shown from another perspective; Figure 4 A schematic diagram of the cross slide assembly according to an embodiment of the present invention is shown; Figure 5 A schematic diagram of the turntable and mounting plate according to an embodiment of the present invention is shown; Figure 6 A schematic diagram of the lead screw fixing module according to an embodiment of the present invention is shown; Figure 7 An enlarged schematic diagram of a portion of the structure of the lead screw fixing module according to an embodiment of the present invention is shown; Figure 8 A schematic diagram of the structure of the central frame according to an embodiment of the present invention is shown; Figure 9 A schematic diagram of the structure of a grinding machine body according to an embodiment of the present invention is shown; Figure 10 A cross-sectional view of the grinding machine body according to an embodiment of the present invention is shown.

[0020] Reference numerals: 1-Grinding machine body; 2-Lead screw fixing module; 201-Worktable; 202-Head clamping frame; 203-Tail clamping frame; 204-Center frame; 205-Sliding seat; 206-First grating ruler; 207-Positioning body; 208-Arc-shaped clamping part; 209-First pushing part; 210-First fixing part; 211-First rotating shaft; 212-Abutting part; 213-Second pushing part; 214-Second fixing part; 215-First body; 216- Second main body; 217-Slide rail body; 218-Limiting component; 3-Grinding wheel module; 301-Turntable; 302-Dressing shaft; 303-Dressing wheel; 304-First slide table; 305-Second slide table; 306-Grinding wheel body; 307-Grinding wheel shaft; 308-Protective cover; 309-Probe part; 310-Transmission part; 311-Mounting plate; 312-Grinding wheel pad; 313-Grinding wheel slide plate; 314-Second grating ruler; 315-Mounting plate; 4-Workpiece to be processed. Detailed Implementation

[0021] The following detailed embodiments are provided to help the reader gain a comprehensive understanding of the methods, apparatus, and / or systems described herein. However, various changes, modifications, and equivalents of the methods, apparatus, and / or systems described herein will be apparent after understanding the disclosure of this application. For example, the order of operations described herein is merely illustrative and is not limited to the order set forth herein; changes that will be apparent after understanding the disclosure of this application are possible, except for operations that must occur in a specific order. Furthermore, for clarity and brevity, descriptions of features known in the art may be omitted.

[0022] The features described herein may be implemented in different forms and should not be construed as being limited to the examples described herein. Rather, the examples described herein have been provided merely to illustrate some of the many feasible ways of implementing the methods, apparatus, and / or systems described herein that will be apparent upon understanding the disclosure of this application.

[0023] Throughout the specification, when an element (such as a layer, region, or substrate) is described as being "on" another element, "connected to" another element, "bonded to" another element, "on" another element, or "covering" another element, it may be directly "on" another element, "connected to" another element, "bonded to" another element, "on" another element, or "covering" another element, or there may be one or more other elements in between. In contrast, when an element is described as being "directly on" another element, "directly connected to" another element, "directly bonded to" another element, "directly on" another element, or "directly covering" another element, there may be no other elements in between.

[0024] As used herein, the term “and / or” includes any one of the relevant items listed and any combination of any two or more items.

[0025] Although terms such as “first,” “second,” and “third” may be used herein to describe individual components, assemblies, regions, layers, or parts, these components, assemblies, regions, layers, or parts are not limited by these terms. Rather, these terms are used only to distinguish one component, assembly, region, layer, or part from another. Therefore, without departing from the teachings of the examples described herein, the first component, assembly, region, layer, or part referred to as the second component, assembly, region, layer, or part may also be referred to as the second component, assembly, region, layer, or part.

[0026] For ease of description, spatial relation terms such as “above,” “upper,” “below,” and “lower” are used herein to describe the relationship between one element and another, as shown in the accompanying drawings. Such spatial relation terms are intended to include not only the orientation depicted in the drawings but also different orientations of the device during use or operation. For example, if the device in the drawings is flipped, an element described as being “above” or “upper” relative to another element will subsequently be “below” or “lower” relative to that other element. Therefore, the term “above” includes both “above” and “below” orientations depending on the spatial orientation of the device. The device may also be positioned in other ways (e.g., rotated 90 degrees or in other orientations), and the spatial relation terms used herein will be interpreted accordingly.

[0027] The terminology used herein is for the purpose of describing various examples only and is not intended to limit the examples. Unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. The terms “comprising,” “including,” and “having” enumerate the stated features, quantities, operations, components, elements, and / or combinations thereof, but do not exclude the presence or addition of one or more other features, quantities, operations, components, elements, and / or combinations thereof.

[0028] Variations in the shapes shown in the accompanying drawings may occur due to manufacturing techniques and / or tolerances. Therefore, the examples described herein are not limited to the specific shapes shown in the accompanying drawings, but include changes in shape that may occur during manufacturing.

[0029] The features of the examples described herein can be combined in various ways that will be apparent upon understanding the disclosure of this application. Furthermore, although the examples described herein have a wide variety of constructions, other constructions are possible, as will be apparent upon understanding the disclosure of this application.

[0030] According to the present invention, an external thread grinding machine for planetary roller screws is provided, such as... Figures 1 to 10 As shown, the planetary roller screw external thread grinding machine is used for high-precision external thread machining of planetary roller screws. The planetary roller screw external thread grinding machine includes a grinding machine body 1, a screw fixing module 2, a grinding wheel grinding module 3, a precision monitoring module, and a control system.

[0031] In the following description, reference will be made to Figures 1 to 10 The specific structure of the aforementioned components of the planetary roller screw external thread grinding machine and the connection relationship of the aforementioned components are described in detail.

[0032] like Figure 1 As shown, in this embodiment, the planetary roller screw is machined using an external thread grinder, i.e. Figure 1 The workpiece 4 is formed into a cylindrical structure. Both ends of the workpiece 4 are clamped to the upper part of the grinding machine body 1 by the lead screw fixing module 2. The grinding wheel grinding module 3 is positioned radially on the workpiece 4 to perform external thread machining. A precision monitoring module is used to monitor and collect real-time working data from the lead screw fixing module 2 and the grinding wheel grinding module 3. The control system (specifically, for example, a PLC) is signal-connected to the precision monitoring module, enabling the collected data to be transmitted to the control system. The control system then applies a quantitative mathematical model based on the collected data to achieve quantitative design and closed-loop compensation.

[0033] Preferably, such as Figure 2 and Figure 6 As shown in the embodiment, the precision monitoring module adopts a distributed integrated structure, which includes a grating ruler assembly, an acoustic emission sensor (not shown), a dynamic balancing instrument (not shown), a six-axis force sensor (not shown), and a probe assembly. Each detection component is connected to the control system signal. The grating ruler assembly is located on the grinding machine body 1, the acoustic emission sensor and the dynamic balancing instrument are located on the grinding wheel module 3, and the probe assembly is located on the rotary table 301, thereby realizing full-dimensional data acquisition.

[0034] Preferably, such as Figure 9 As shown, in this embodiment, the grinding machine body 1 includes a lead screw slide and a grinding wheel slide. The lead screw fixing module 2 is movably disposed in the lead screw slide, and the grinding wheel grinding module 3 is slidably disposed in the grinding wheel slide. The grating ruler assembly includes a first grating ruler 206 and a second grating ruler 314. The first grating ruler 206 is disposed in the lead screw slide, and the second grating ruler 314 is disposed in the grinding wheel slide, to monitor the lead screw fixing module 2 and the grinding wheel grinding module 3 respectively.

[0035] Furthermore, the grinding machine body 1 can be integrally formed from a mineral casting material (such as artificial marble), and the whole can be formed into a T-shaped structure, that is, the lead screw slide and the grinding wheel slide are set perpendicular to each other. The extension direction of the lead screw slide is defined as the linear Z-axis, and the extension direction of the grinding wheel slide is defined as the linear X-axis. The damping coefficient of the mineral casting material of the grinding machine body 1 is 3-5 times that of cast iron, which can effectively suppress processing vibration and thermal deformation, laying the foundation for the overall machine accuracy.

[0036] Furthermore, to improve the machining accuracy of the workpiece 4, the grinding module 3 can perform grinding of the workpiece 4 while simultaneously dressing the grinding wheel body 306. In the prior art, the grinding wheel body 306 is typically used for preliminary machining of the workpiece 4, followed by dressing to conform to the required tooth profile, compensating for deviations caused by wear during machining. However, when the workpiece 4 is a long-stroke material, the grinding wheel body 306 may experience significant wear in the first half of the grinding process, leading to a sharp decrease in accuracy in the latter half, resulting in reduced forming accuracy and product quality of the workpiece 4. Moreover, dressing the grinding wheel body 306 requires machine downtime, and frequent dressing reduces machining speed, impacting production progress. Based on this, the grinding wheel module 3 has been improved in design so that the grinding wheel body 306 can perform grinding and dressing at the same time. That is, the grinding wheel body 306, the dressing wheel 303 and the workpiece 4 are in contact at the same time and carry out grinding work together. During the processing of the workpiece 4 and after the processing is completed, the probe assembly performs accuracy detection in a timely manner.

[0037] Specifically, such as Figure 2 and Figure 3As shown, in this embodiment, the grinding wheel module 3 includes a rotary table 301, a grinding wheel assembly, and a dressing assembly. The rotation axis of the rotary table 301 is defined as the A-axis. A probe assembly is disposed on the rotary table 301, which drives the grinding wheel assembly, dressing assembly, and probe assembly to rotate around the A-axis. Specifically, the rotary table 301 can be driven by a torque motor in conjunction with a circular grating (resolution 0.001°). The dressing assembly is adjustablely positioned on the upper part of the grinding wheel assembly, and the probe assembly includes a probe portion 309, which is oscillatingly disposed on the side of the grinding wheel assembly. During processing, the grinding wheel assembly is positioned radially to the workpiece 4 for grinding. The adjustable dressing assembly, positioned on the upper part of the grinding wheel assembly, allows for timely dressing of the grinding wheel body 306 by adjusting its position, ensuring the dimensional accuracy of the grinding wheel body 306. The probe assembly is located on the side of the grinding wheel assembly. When the grinding wheel assembly is working, the probe part 309 retracts to the lower part of the probe assembly to avoid interference during processing. After the grinding wheel assembly grinds the workpiece 4 once, the probe part 309 can be rotated to extend out of the probe assembly, and the position of the grinding wheel grinding module 3 on the grinding machine body 1 can be adjusted so that the probe part 309 contacts the ground external thread. The lead screw fixing module 2 is moved in the opposite direction to the processing direction so that the probe part 309 contacts and detects the ground external thread and provides feedback on the processing data. This allows for intuitive monitoring of the processing status of the external thread and the accuracy of the lead screw after processing, facilitating compensation based on the existing processing accuracy. The probe part 309 can rotate by, for example, by having a pivot shaft connected to the end of the probe part 309 at the lower part of the probe assembly. The probe part 309 can be swung and adjusted in position via the pivot shaft so that the contact end of the probe part 309 can contact the workpiece 4. Preferably, the swing range of the probe portion 309 can be 0° to 90°, and the detection end of the probe portion 309 is made of ruby ​​(resolution 0.001mm).

[0038] Preferably, such as Figure 3As shown, in this embodiment, the grinding wheel body 306 can be made of cubic boron nitride material with a diameter of 400mm. The grinding wheel spindle 307 is an electric spindle (speed 0-6000r / min). A dynamic balancing instrument and an acoustic emission sensor are installed in the grinding wheel module 3. Specifically, the dynamic balancing instrument is installed inside the grinding wheel spindle 307, and the acoustic emission sensor is installed on the upper part of the grinding wheel spindle 307 (sampling frequency 1-100kHz) to collect grinding signals in real time, thereby detecting and correcting the dynamic imbalance of the grinding wheel body 306, improving the dimensional accuracy and working stability of the workpiece 4. The acoustic emission sensor can detect, capture, and receive acoustic emission signals generated inside the material or structure. By detecting grinding sounds, it realizes intelligent monitoring and in-situ dressing functions, facilitating timely position adjustment of the dressing components during processing to dress the grinding wheel body 306, and also monitoring and providing feedback on the processing status and accuracy. It should be noted that the probe assembly, dynamic balancing instrument, and acoustic emission sensor mentioned above can all be existing devices, such as contact probes. Their structures, connection methods, and data feedback methods are known to those skilled in the art and will not be elaborated here. The key is to achieve the detection of the machining accuracy of the external thread and to monitor and feedback data in real time. The feedback data can be displayed on an external control console (not shown), allowing the operator to promptly understand the current machining status.

[0039] Preferably, in this embodiment, both the lead screw slide and the grinding wheel slide of the grinding machine body 1 are equipped with a linear motor direct drive system, enabling the lead screw fixing module 2 and the grinding wheel grinding module 3 to achieve electric direct drive displacement adjustment. This solves the backlash problem caused by the worm gear or gear transmission connection in traditional external thread grinding machines, and is suitable for high-precision planetary roller lead screw machining. Specifically, the motor direct drive system includes a linear motor and a magnetic plate. In the lead screw slide and the grinding wheel slide, both the lead screw fixing module 2 and the grinding wheel grinding module 3 are driven by a linear motor and positioned by a grating ruler assembly to achieve position changes. Furthermore, a magnetic plate is laid in the lead screw slide or the grinding wheel slide, and the magnetic plate is installed in the grinding machine body 1 by bolt connection. Through the cooperation of the linear motor and the magnetic plate, the direct drive motion of the linear motor and excellent control effect are achieved.

[0040] Meanwhile, through the cooperation of the rotary table 301, grinding wheel assembly, dressing assembly and probe assembly of the grinding wheel module 3, the planetary roller screw external thread grinder can dress the grinding wheel body 306 while the grinding wheel body 306 grinds the workpiece 4, thus solving the accuracy error caused by the thread helix angle and forward and reverse rotation during grinding wheel dressing and thread grinding, and improving the processing accuracy and processing efficiency.

[0041] Preferably, such as Figures 2 to 4As shown, in this embodiment, the dressing assembly may include a dressing shaft 302, a dressing wheel 303, and a cross slide assembly. The cross slide assembly includes a first slide 304 and a second slide 305 arranged perpendicularly to each other. The extension direction of the first slide 304 is defined as the linear Y-axis, and the extension direction of the second slide 305 is defined as the linear W-axis. The first slide 304 is slidably mounted on the second slide 305, the dressing shaft 302 is slidably mounted on the first slide 304, and the dressing wheel 303 is disposed at the end of the dressing shaft 302. The dressing wheel 303 adjusts its contact position with the grinding wheel assembly via the cross slide assembly to dress the grinding wheel assembly. The cross slide assembly can be driven by a servo motor and a ball screw, with a positioning accuracy of 0.001 mm. The grinding wheel body 306 can be a diamond roller. Because the grinding wheel body 306 contacts the workpiece 4 at different positions and depths during external thread machining, wear may occur at different locations. Therefore, the grinding wheel body 306 needs to be adjusted and dressed according to the different wear locations. Since the first slide 304 and the second slide 305 are arranged perpendicularly to each other, the dressing shaft 302 can move in two perpendicular directions, thereby enabling the dressing wheel 303 to adjust its position and be dressed according to the required tooth profile. The cross slide assembly can be understood as two perpendicular slide rails connected by a lead screw or driven by a cylinder to move the slider on the slide rails. For example, the second slide 305 can be understood as the slide rail, and the first slide 304 can be understood as the slider sliding on the second slide 305. The first slide 304 itself can be understood as another slide rail, and the dressing shaft 302 can be understood as the slider sliding on the first slide 304.

[0042] Preferably, such as Figure 2 and Figure 3 As shown, in this embodiment, the grinding wheel assembly may include a grinding wheel body 306 and a grinding wheel shaft 307. The grinding wheel body 306 is disposed at the end of the grinding wheel shaft 307, and the grinding wheel shaft 307 drives the grinding wheel body 306 to rotate. The grinding wheel body 306 and the grinding wheel shaft 307 may be common or specially made (for processing workpiece 4 made of high-hardness materials). The grinding wheel shaft 307 may be driven by an external electric motor and drive the grinding wheel body 306 to rotate via a coupling or direct connection.

[0043] Preferably, such as Figure 2 and Figure 3As shown, in this embodiment, the probe assembly includes a probe section 309 and a transmission section 310. The transmission section 310 is mounted on the outer wall of the grinding wheel shaft 307 via a mounting plate 311. Specifically, to facilitate detection by the probe assembly while avoiding interference, the mounting plate 311 can be mounted on the outer wall of the housing of the grinding wheel shaft 307 using a bolt connection. The transmission section 310 can transmit the signal detected by the probe section 309 to an external control console. The first end of the probe section 309 is the detection end, and the second end of the probe section 309 is pivotally connected to the transmission section 310. The pivotal connection is achieved by providing a pivot shaft at the lower part of the probe assembly, which connects to the end of the probe section 309. The probe section 309 is pivotally connected to the transmission section 310 via the pivot shaft.

[0044] Thus, when the planetary roller screw external thread grinding machine is working, the grinding wheel body 306 processes the planetary roller screw (i.e., the workpiece 4 to be processed), the dressing wheel 303 contacts the grinding wheel body 306, and after the planetary roller screw is processed, the detection end of the probe part 309 contacts the external thread groove surface of the planetary roller screw after processing, so as to detect the processing accuracy and provide feedback on the processing status.

[0045] Preferably, such as Figure 2 and Figure 3 As shown, in this embodiment, the grinding wheel module 3 may further include a grinding wheel slide plate 313 and a grinding wheel pad 312 disposed at the bottom of the turntable 301. The turntable 301 is connected to the grinding wheel slide plate 313 via the grinding wheel pad 312, and the grinding wheel slide plate 313 is slidably connected to the grinding wheel track. A second grating ruler 314 is disposed on the side of the grinding wheel slide plate 313, and the resolution of the second grating ruler 314 can be 0.1μm. A sliding block is disposed at the bottom of the grinding wheel slide plate 313 and is slidably connected to the grinding wheel track, allowing the grinding wheel slide plate 313 to be slidably disposed on the grinding wheel track. The second grating ruler 314 can perform high-precision position detection and error compensation for the grinding wheel module 3 on the grinding machine body 1. The grinding wheel pad 312 can be height-calibrated by grinding to ensure that the grinding wheel body 306 is at the same height as the axis of the workpiece 4 to be processed (coaxiality error ≤0.002mm).

[0046] Preferably, such as Figure 5 As shown in the embodiment, to facilitate the installation and synchronous operation of the grinding wheel assembly, dressing assembly, and probe assembly, the grinding wheel module 3 may further include a mounting plate 315. The rotary table 301 is rotatably connected to the mounting plate 315, and the grinding wheel assembly, dressing assembly, and probe assembly are all mounted on the mounting plate 315. The cross slide assembly can be bolted to the mounting plate 315 of the rotary table 301. The rotary table 301 can drive the mounting plate 315 to rotate via a centrally located rotation axis (i.e., axis A), thereby allowing the grinding wheel assembly, dressing assembly, and probe assembly to adjust their angles.

[0047] Preferably, such as Figure 2 As shown in the embodiment, a protective cover 308 is provided on the outside of the grinding wheel body 306. The protective cover 308 can protect the relatively large grinding wheel body 306, ensuring that only the grinding part of the grinding wheel body 306 is outside the protective cover 308, thus preventing damage to the grinding wheel body 306 from flying debris during grinding and dressing. The protective cover 308 includes a fixed part and an opening part. The fixed part is fixedly installed on the mounting plate 315 by bolts, and the opening part is rotatably connected to the fixed part by a rotating shaft. A handle is provided at the end of the opening part, allowing the user to pull open the opening part and replace the grinding wheel body 306.

[0048] Preferably, such as Figure 1 , Figure 6 and Figure 7 As shown, in this embodiment, the lead screw fixing module 2 may include a worktable 201, a head clamping frame 202, a tail clamping frame 203, and a center frame 204. Multiple sets of center frames 204 can be used to adapt to long-stroke machining (e.g., 3m), and the center frames 204 can be hydrostatic follow-type center frames. The head clamping frame 202, tail clamping frame 203, and multiple sets of center frames 204 are all slidably mounted on the worktable 201 via sliding seats 205. Since the length and diameter of each batch of workpieces 4 to be processed are different, it is necessary to clamp workpieces 4 of different specifications specifically. Therefore, the head clamping frame 202, tail clamping frame 203, and center frame 204 can all be slidably arranged on the worktable 201. Sliding seats 205 are provided at the bottom of the head clamping frame 202, tail clamping frame 203, and center frame 204. The sliding seats 205 can be understood as sliders and slide on the worktable 201. Specifically, the top of the workbench 201 is equipped with a slide rail forming an approximately inverted trapezoidal structure. The sliding seat 205 includes a base plate and two V-shaped locking blocks. The two V-shaped locking blocks are installed at both ends of the base plate by bolt connection. The two V-shaped locking blocks contact the two side walls of the slide rail respectively to achieve sliding. The head clamping frame 202, the tail clamping frame 203, and the center frame 204 are installed on the base plate by bolt connection. To ensure the stability of sliding, the size of the base plate will be adjusted accordingly depending on the size of the head clamping frame 202, the tail clamping frame 203, and the center frame 204, and the number of V-shaped locking blocks at both ends of the base plate will also be increased accordingly.

[0049] Furthermore, the rotation axis of the head clamping bracket 202 is defined as the C-axis. It is driven and positioned by a torque motor in conjunction with a circular grating (circular grating resolution 0.001°), and one end of the workpiece 4 is clamped by a Morse No. 6 hydrostatic center. A shift fork drives its high-precision rotation (i.e., drives the workpiece 4 to rotate around the C-axis). The tail clamping bracket 203 is a constant force adaptive thermal compensation tailstock. A six-axis force sensor (range 0-500N, resolution 0.1N) is integrated at the end of the tail clamping bracket 203. Through the six-axis force sensor in conjunction with the aforementioned acoustic emission sensor and contact probe, the machining status of the external thread grinding machine can be intuitively monitored.

[0050] Furthermore, a first grating ruler 206 is disposed on the side of the worktable 201, and the resolution of the first grating ruler 206 can be 0.1μm. The first grating ruler 206 can be installed on the side of the worktable 201 by bolt connection. The first grating ruler 206 can be used to perform high-precision position detection and error compensation of the lead screw fixing module 2 on the grinding machine body 1 (i.e., to realize Z-axis position detection and error compensation).

[0051] Preferably, such as Figure 1 , Figure 6 and Figure 7 As shown in the embodiment, both the head clamping frame 202 and the tail clamping frame 203 are provided with clamping frame pads at their bottoms. The head clamping frame 202 and the tail clamping frame 203 are each connected to the sliding seat 205 via a clamping frame pad, and the connection is made by bolts. By adjusting the thickness of the clamping frame pads, the height of the head clamping frame 202 and the tail clamping frame 203 can be adjusted to cooperate with the grinding wheel grinding module 3 and ensure that the axis of the grinding wheel body 306 and the axis of the workpiece 4 are at the same height.

[0052] Preferably, such as Figure 8As shown, in this embodiment, the center frame 204 may include a positioning body 207, a first pressure rod, a second pressure rod, and a third pressure rod. The first pressure rod, the second pressure rod, and the third pressure rod are sequentially arranged vertically on the positioning body 207. Both the first pressure rod and the third pressure rod include an arc-shaped clamping portion 208, a first pushing portion 209, and a first fixing portion 210. The arc-shaped clamping portion 208 may be made of zirconia engineering ceramic material. One end of the arc-shaped clamping portion 208 extends out of the positioning body 207, and the other end of the arc-shaped clamping portion 208 is connected to the positioning body 207 in an adjustable position via the first pushing portion 209. Specifically, the adjustable connection method is, for example, that the first pushing portion 209 is connected to the end of the arc-shaped clamping portion 208 via a pushing rod, and the pushing rod drives the arc-shaped clamping portion 208 to change position. The first fixing part 210 passes through the arc-shaped clamping part 208 and the positioning body 207. The positioning body 207 has an oblong hole with an arc shape, and the first fixing part 210 passes through this oblong hole. The first fixing part 210 can be, for example, a clamping bolt. After the arc-shaped clamping part 208 is adjusted into place by the first pushing part 209, the arc-shaped clamping part 208 can be locked by turning the first fixing part 210. The arc-shaped clamping part 208 is rotatably mounted on the positioning body 207 via the first rotating shaft 211. The arc-shaped clamping parts 208 of the first pressure rod and the arc-shaped clamping parts 208 of the third pressure rod are symmetrically arranged to clamp the upper and lower end faces of the planetary roller screw, respectively.

[0053] Furthermore, the second pressure rod includes an abutment portion 212, a second pushing portion 213, and a second fixing portion 214. One end of the abutment portion 212 passes through the positioning body 207 and abuts against the planetary roller screw. The other end of the abutment portion 212 is connected to the second pushing portion 213. The second fixing portion 214 passes through the abutment portion 212 and the positioning body 207. The second pushing portion 213 is connected to the abutment portion 212 via a pushing rod, which drives the abutment portion 212 to extend out of the positioning body 207. The second fixing portion 214 can be, for example, a clamping bolt. A waist-shaped hole is provided in the middle of the locking abutment portion 212. The second fixing portion 214 passes through this waist-shaped hole, and the abutment portion 212 can be locked by screwing the second fixing portion 214. The arc-shaped clamping portion 208 of the first pressure rod, the abutment portion 212, and the arc-shaped clamping portion 208 of the third pressure rod surround and clamp the planetary roller screw to form a three-contact fixed-circle clamping structure.

[0054] Preferably, such as Figure 9 and Figure 10As shown, in this embodiment, the grinding machine body 1 is formed into a T-shaped structure. The T-shaped structure includes a first body 215 and a second body 216 that intersect each other perpendicularly. A lead screw slide is disposed in the first body 215, and a grinding wheel slide is disposed in the second body 216. A slide rail can be disposed inside the T-shaped structure. The slide rail is disposed in the grinding machine body 1 of the T-shaped structure by means of a threaded connection. In order to ensure stable movement, both the lead screw slide and the grinding wheel slide can include two parallel slide rails. The magnetic plate of the linear motor direct drive system can be disposed between the two slide rails.

[0055] Preferably, such as Figure 9 and Figure 10 As shown in the embodiment, both the lead screw slide and the grinding wheel slide are provided with U-shaped grooves. A slide rail body 217 is installed inside the U-shaped groove and is directly installed into the U-shaped groove by bolts. To prevent slippage, both ends of the lead screw slide and the grinding wheel slide are provided with polyurethane limiting members 218 to limit the movement stroke of the lead screw fixing module 2 and the grinding wheel grinding module 3.

[0056] Preferably, such as Figure 9 and Figure 10 As shown in the embodiment, wedge blocks are provided on the sides of the lead screw slide and the grinding wheel slide. The wedge blocks, the limiting member 218 and the magnetic plate are all installed on the lead screw slide and the grinding wheel slide by means of bolt connection. The wedge blocks are used to provide installation support.

[0057] Thus, the grinding wheel module 3 actually includes four-axis motion: the sliding of the rotary table 301 on the grinding wheel slideway (X-axis motion), the axial rotation of the mounting plate 315 driven by the rotary table 301 (A-axis motion), and the sliding of the cross slide assembly in two mutually perpendicular directions (W-axis motion and Y-axis motion). The grinding wheel module 3, together with the sliding of the lead screw fixing module 2 on the lead screw slideway (Z-axis motion) and the rotation of the workpiece 4 (C-axis motion), forms a multi-axis linkage system for the planetary roller lead screw external thread grinder.

[0058] This planetary roller screw external thread grinding machine features multi-axis linkage, real-time monitoring, synchronous grinding, and dressing functions. Its specific working process is as follows: The first step is to clamp the workpiece 4. When machining the planetary roller screw (workpiece 4), multiple center supports 204 are installed on the worktable 201 to clamp and center the workpiece 4. The workpiece 4 is fixed by the multiple center supports 204, the top of the head clamping frame 202 and the top of the tail clamping frame 203. The head clamping frame 202 uses a shift fork to drive the workpiece 4 to rotate.

[0059] Second, adjust the position. The turntable 301 drives the grinding wheel body 306 to swing to the same angle as the thread helix angle of the workpiece 4 to be processed. At the same time, make the axis of the workpiece 4 parallel to the axis of the grinding wheel body 306 and at the same height. Start the head clamping frame 202 and the grinding wheel motor to make the workpiece 4 and the grinding wheel body 306 rotate. The linear motors of the Z axis and X axis are jointly controlled to drive the worktable 201 and the turntable 301 to move.

[0060] Third, grinding begins. The rotary table 301 is controlled to approach the workpiece 4 to begin grinding, and the worktable 201 moves along the Z-axis until the planetary roller screw is ground. During grinding, the cross slide assembly is linked to move along the Y and W axes, so that the dressing wheel 303 contacts the grinding wheel body 306 and is dressed according to the required tooth profile. The dressing wheel 303, the grinding wheel body 306, and the workpiece 4 work simultaneously.

[0061] Fourth, inspection: After the planetary roller screw has been machined for one revolution, the worktable 201 and the rotary table 301 are moved in opposite directions to open the probe part 309 of the probe assembly. The worktable 201 and the rotary table 301 are then linked to carry out machining inspection, extract the machining data of the planetary roller screw and start program compensation. The worktable 201 and the rotary table 301 are then controlled to retract, and a new round of grinding is carried out based on the program compensation results and feed parameters.

[0062] In addition, such as Figures 1 to 10 As shown, according to a second aspect of the present invention, a design method for a planetary roller screw external thread grinding machine is provided, wherein the design method for the planetary roller screw external thread grinding machine is applied to the planetary roller screw external thread grinding machine described above. The design method for the planetary roller screw external thread grinding machine includes: a thermally symmetrical and constant-force thermal compensation structure design for long-stroke machining; a flexible adaptive clamping design for the center rest 204; a grinding and repair collaborative dynamic compensation structure design based on acoustic emission monitoring; a thermal insulation and cooling structure design for the linear motor direct drive system; and an in-situ detection by the probe section 309 and indexing error modeling and path compensation design for multi-start threads.

[0063] Specifically, the design method for the planetary roller screw external thread grinding machine achieves quantitative control through quantitative design formulas, mathematical models, real-time calculations, and closed-loop compensation. Specifically, the thermal symmetry and constant force thermal compensation structure design for long-stroke machining utilizes a constant force adaptive thermal compensation tailstock (i.e., tail clamping frame 203) designed using a screw thermal expansion calculation model and an axial stress-yield correlation model to achieve constant force expansion and contraction compensation for screw thermal expansion. The flexible adaptive clamping design of the center frame 204 utilizes a hydrostatic oil film pressure model and an oil film gap-clamping force correlation model to design a hydrostatic following center frame, achieving non-contact flexible clamping. The grinding-repair collaborative dynamic compensation structure design based on acoustic emission monitoring establishes a closed-loop compensation system of acoustic emission monitoring-feed linkage through an acoustic emission-grinding wheel wear fitting model, achieving constant grinding wheel profile. The thermal insulation and cooling structure design of the linear motor direct drive system utilizes a three-dimensional structure for thermal insulation, cooling, and thermal isolation designed using a linear motor thermal deformation calculation model and a heat dissipation power calculation model to eliminate thermal interference from the linear motor direct drive system. The probe section 309 is used for in-situ detection and indexing error modeling and path compensation design of multi-start threads. The error mathematical model of multi-start threads is combined with the least squares fitting algorithm to achieve dual compensation for the starting point and the machining path.

[0064] Preferably, such as Figure 6 and Figure 7 As shown, in this embodiment, the tail clamping frame 203 is further equipped with a retractable tip and a hydraulic telescopic mechanism. The retractable tip is connected to the tail clamping frame 203 via the hydraulic telescopic mechanism, and a six-axis force sensor is integrated into the end of the retractable tip. The six-axis force sensor is connected to the hydraulic telescopic mechanism and the control system. This allows the control system to use a lead screw thermal expansion calculation model. Calculate the axial elongation. Simultaneously, the control system can utilize an axial stress-yield correlation model. Adjust the tip retraction amount ΔS in real time to maintain a constant clamping force.

[0065] Furthermore, the design of a thermally symmetrical and constant-force thermal compensation structure for long-stroke machining may include the following steps: The axial elongation of the lead screw under different temperature rises is calculated using the thermal expansion calculation model of the lead screw. The telescopic tip is designed as a hydraulically driven elastic structure, and an axial margin matching the elongation is reserved. A six-axis force sensor is integrated at the end of the retractable tip, a first temperature sensor is attached to the workpiece 4, and the first temperature sensor and the six-axis force sensor are respectively connected to the control system signal. The quantitative relationship between stress and tip relief is established through the axial stress-relief correlation model. A constant clamping force adaptive adjustment program is written into the control system, a threshold of clamping force is preset, and the tip relief amount is calculated and adjusted in real time based on the detection data and the axial stress-relief amount correlation model. The head clamp 202 adopts a fixed-axis rotation design, which makes the constant force telescopic tip of the head clamp 202 and the tail clamp 203 form a thermally symmetrical structure, thereby preventing the workpiece 4 from undergoing micro-bending.

[0066] Specifically, in the embodiment, in the thermal expansion calculation model of the lead screw Axial stress-yield correlation model In the figure, ΔL represents the thermal elongation of the planetary roller screw (mm), and α represents the thermal elongation of the planetary roller screw. s Here, L0 is the linear expansion coefficient of the lead screw base material (°C), L0 is the effective length of the lead screw machining reference (mm), ΔT is the temperature rise during lead screw machining, σ is the axial thermal stress of the lead screw, Es is the elastic modulus of the lead screw base material, and ΔS is the axial allowance compensation of the tailstock center. The lead screw is made of GCr15 material (α... s =11.5×10 -6 Taking the following parameters as an example: machining stroke L0 = 3000 mm, temperature rise ΔT = 10℃, Es = 2.06 × 10⁵ MPa, target clamping stress: σ0 = 0.025 MPa (corresponding to clamping force 100 N), the final calculation yields: ΔL = 0.345 mm, ΔS ≈ 0.3446 mm. Conclusion: When the temperature rise is 10℃, the lead screw elongates by 0.345 mm, the tailstock retracts by 0.345 mm, and the clamping force remains constant at 100 N to prevent micro-bending of the workpiece 4.

[0067] Preferably, the center rest 204 is a hydrostatic follower type center rest, and the center rest 204 is equipped with a hydrostatic support system. The hydrostatic support system includes a high-pressure oil circuit, and micro-oil holes are formed on the ends of the arc-shaped clamping part 208 and the abutment part 212 (i.e., the clamping surfaces of the arc-shaped clamping part 208 and the abutment part 212). The oil circuit and the oil holes are connected to form a high-pressure oil film of 5μm to 10μm. The sliding mating surface between the center rest 204 and the worktable 201 is a hydrostatic guide rail structure with a following accuracy of ≤0.002mm, thereby avoiding scratching of the machined threads during long-stroke movement. The center rest 204 is based on a hydrostatic oil film pressure model. Oil film gap-clamping force correlation model Achieve contactless flexible clamping.

[0068] Furthermore, the flexible adaptive clamping design of the center frame 204 may include the following steps: By using the hydrostatic oil film pressure model and the oil film gap-clamping force correlation model, the target oil film gap and oil supply pressure corresponding to different nominal screw diameters are calculated, and the core design parameters of the center frame 204 clamping structure are determined. Based on the three-contact fixed circle clamping structure, the arc-shaped clamping part 208 is made of low-hardness and high-wear-resistant engineering ceramic material (such as zirconia engineering ceramic), and oil holes are opened on the clamping surfaces of the arc-shaped clamping part 208 and the abutment part 212. A hydrostatic support system including a high-pressure oil pump, a high-pressure oil circuit and a pressure sensor is configured, and the sliding mating surface between the center frame 204 and the worktable 201 is designed as a hydrostatic guide rail structure. Connect the pressure sensor to the control system signal, establish the quantitative relationship between oil supply pressure and clamping force through the oil film gap-clamping force correlation model, and preset the clamping force threshold of a single clamping part. An adaptive oil film pressure adjustment program is written into the control system. Based on the detection data of the pressure sensor and the correlation model of the oil film gap-clamping force, the oil pump supply pressure is adjusted in real time to ensure that the oil film gap is stable between 5μm and 10μm.

[0069] Specifically, in the embodiments, in the hydrostatic oil film pressure model Oil film gap-clamping force correlation model In this diagram, p represents the real-time working pressure of the oil film, Q represents the high-pressure hydraulic oil supply, μ represents the dynamic viscosity of the hydraulic oil, L_cx represents the axial effective length of the arc-shaped clamping part 208 of the center frame 204, x represents the axial distance between the pressure calculation point and the oil hole, h represents the oil film gap thickness, B_c represents the circumferential effective width of the arc-shaped clamping part 208 of the center frame 204, p0 represents the hydraulic system supply pressure, F_c represents the clamping force of the oil film in a single clamping part, k represents the oil film pressure correction coefficient (dimensionless), and S_c represents the effective contact area of ​​the oil film. (Q = 5 × 10⁻⁶) 8m 3 / s (oil supply rate), μ=0.046Pa.s (viscosity of 46# hydraulic oil), x=Lc=0.1m (oil hole position), h=10μm=10×10 6 m (oil film gap), Bc = 0.05m (circumferential width of clamping part), p0 = 3MPa = 3 × 10 6 Pa (supply pressure), k=0.85 (correction factor), Sc=5×10 3 m 2 Taking (effective oil film area) as an example, the final calculation yields: =1.38×10 11 , =3×10 6 p = 4.6 × 10 18Pa, F_c=127.5N. Conclusion: When the oil supply pressure is 3MPa and the oil film gap is 10μm, the clamping force is 127.5N, and the system is stable without scratches.

[0070] Preferably, the planetary roller screw external thread grinding machine is equipped with a grinding-over-wear dynamic compensation system. The grinding-over-wear dynamic compensation system includes a grinding wheel wear signal feature library and a cross slide assembly drive system. An acoustic emission sensor is signal-connected to the control system and the cross slide assembly drive system; the acoustic emission sensor is located on the upper part of the grinding wheel shaft 307 and close to the grinding wheel body 306. The control system uses the acoustic emission signal effective value formula... Feature values ​​were extracted and stored in a grinding wheel wear signal feature library, along with a fitting model based on acoustic emission and grinding wheel wear. Calculate the real-time wear amount and sequentially drive the cross slide assembly to feed, ensuring the feed rate meets the requirements. .

[0071] Furthermore, the design of a collaborative dynamic compensation structure for grinding and repair based on acoustic emission monitoring may include the following steps: An acoustic emission sensor is integrated on the upper part of the grinding wheel shaft 307, with the detection end close to the grinding wheel body 306, so that the acoustic emission sensor forms a closed-loop signal connection with the control system and the cross slide assembly drive system, so as to collect acoustic emission signals in real time, extract feature values ​​through the effective value formula, and store them in the grinding wheel wear signal feature library. The characteristic values ​​of the acoustic emission signal of the grinding wheel under different wear conditions and the actual wear amount were obtained through preliminary experiments. The acoustic emission-grinding wheel wear amount fitting model was established by a univariate linear fitting algorithm and entered into the control system. The cross slide table feed linkage program is designed. The control system calculates the real-time wear of the grinding wheel body 306 based on the real-time detected characteristic values ​​through the acoustic emission-grinding wheel wear fitting model, and drives the cross slide table assembly to make feed adjustments according to the feed formula. A closed-loop control system is implemented to monitor acoustic emission, calculate wear, and adjust feed, ensuring that the dressing amount of the dressing wheel 303 is precisely matched with the grinding consumption of the grinding wheel body 306.

[0072] Specifically, in the embodiment, the formula for the effective value of the acoustic emission signal is... Acoustic emission-grinding wheel wear fitting model and feed rate formula In this context, RMS represents the effective value of the acoustic emission signal (a characteristic quantity of grinding wheel wear), T represents the sampling period of the acoustic emission signal, t represents the signal sampling time variable, x(t) represents the instantaneous amplitude of the acoustic emission signal at time t, and ΔG represents the wear amount of a single tooth of the grinding wheel. For grinding wheel wear The slope coefficient of the acoustic emission signal fitting, b represents the wear of the grinding wheel. The acoustic emission signal fitting intercept coefficient, k_f (dimensionless) is the grinding wheel dressing feed matching coefficient, and Δf is the radial feed compensation of the diamond dressing wheel 303. Taking T=0.01s, a=0.005μm / mV, b=0.002μm, and k_f=1.05 as an example, the final calculated values ​​are: RMS=40mV, ΔG=0.202μm, and Δf=0.212μm. Conclusion: The grinding wheel wear is 0.202μm, the dressing feed is 0.212μm, and the profile is stable.

[0073] Preferably, the linear motor direct drive system is equipped with a heat insulation and cooling structure, which may include a heat insulation pad, cooling channels, thermally insulated connectors, and a heat insulation protective cover. The heat insulation pad is located between the U-shaped groove and the magnetic plate, and the cooling channels are located on both sides of the U-shaped groove. The planetary roller screw is equipped with a water cooling system, which is connected to the cooling channels to provide coolant. The mover of the linear motor is connected to the moving parts using thermally insulated connectors. The heat insulation protective cover is installed on the grating ruler assembly (i.e., on the first grating ruler 206 and the second grating ruler 314). The stator of the linear motor is equipped with a second temperature sensor, which is connected to the control system signal. The control system uses the thermal deformation calculation model of the linear motor. and heat dissipation power calculation model Achieve quantitative control of thermal deformation to ensure that the stator temperature rise of the linear motor is ≤5℃.

[0074] Furthermore, the structural design of the thermal insulation and cooling system for a linear motor direct drive system may include the following steps: The thermal deformation calculation model is used to calculate the stator thermal deformation of the linear motor under different temperature rises. Combined with the heat dissipation power calculation model, the heat dissipation power requirement of the thermal insulation and cooling structure is determined, and the structural design standards for thermal insulation, cooling and thermal isolation are defined. A heat insulation pad is installed between the U-shaped groove and the magnetic plate. Cooling channels extending along the length of the slide are opened on both sides of the U-shaped groove and connected to the water cooling system. A heat-isolated connector is installed between the mover and the moving parts of the linear motor. A heat insulation protective cover is added to the grating ruler assembly. The second temperature sensor is attached to the stator of the linear motor, and the second temperature sensor is connected to the water cooling system through the control system signal to establish a quantitative relationship between the motor temperature rise and the coolant flow rate. A thermal deformation adaptive adjustment program is written into the control system. Based on the detection data of the second temperature sensor and the thermal deformation calculation model, the coolant flow rate of the water cooling system is adjusted in real time to ensure that the stator temperature rise of the linear motor is ≤5℃.

[0075] Specifically, in the embodiment, in the thermal deformation calculation model and heat dissipation power calculation model In the middle, ΔL mFor the thermal deformation of the linear motor stator, α m The coefficient of linear expansion of the motor stator material, L m For the effective length of the linear motor stator, ΔT m For the stator operating temperature rise of the motor, P_ 散 For the heat dissipation power of the water cooling system, K_ 散 For the convective heat dissipation coefficient of cooling water, S_ 散 This represents the effective heat dissipation area of ​​the cooling channel. Using α... m =23.8×10 6 / C (aluminum alloy), L m =3000mm, ΔT m =5 C (allowable temperature rise), K_ 散 =500W / (m 2 ℃), P_ 散 Taking 500W as an example, the final calculation yields: ΔL m =0.357mm, S_ 散 =0.2m 2 Conclusion: Temperature rise ≤ 5℃, thermal deformation ≤ 0.357mm, and cooling area of ​​0.2m² meet the standards.

[0076] Preferably, the planetary roller screw external thread grinding machine is equipped with a multi-start thread detection and compensation system, which includes an error mathematical model. The probe part 309 of the probe assembly is connected to the torque motor and the first grating ruler 206 for signal transmission. The detection path of the probe part 309 follows the parametric equation of the planetary roller screw helical trajectory. This enables three-axis linkage between the probe section 309 and the C-axis and Z-axis. The control system uses a least-squares fitting algorithm to establish an error mathematical model for multi-start thread machining. and through and Reverse compensation is performed on the C-axis and Z-axis. The error mathematical model includes the indexing error of the C-axis, the feed error of the Z-axis, and the helix angle error. The multi-start thread detection and compensation system realizes pre-compensation and real-time compensation of machining errors by controlling the grinding wheel module 3.

[0077] Furthermore, the in-situ detection of the probe section 309 and the modeling and path compensation design of the indexing error of the multi-start thread include the following steps: Establish a three-axis linkage signal connection between the probe assembly, torque motor and first grating ruler 206, set the basic parameters of the workpiece 4 to be processed (e.g., set the number of thread starts, pitch, etc.), and plan the detection path of the probe part 309 through the spiral trajectory formula; Using the end face of the lead screw blank as a reference, the micron-level precise positioning of the starting point of the multi-start thread is achieved through the angular indexing of the C-axis and the axial positioning of the Z-axis, and the coordinates of each starting point position are recorded. After single-start thread grinding, the probe 309 is used to detect along the helical trajectory and extract pitch and indexing error data. The least squares fitting algorithm is used to establish the error mathematical model of multi-start thread machining, which includes the indexing error of the C-axis, the feed error of the Z-axis, and the helix angle error. The linkage path compensation program is designed to calculate the compensation amount in real time based on the error mathematical model, and to perform pre-compensation and real-time compensation for subsequent thread head processing. After the full stroke processing, the probe part 309 is used for re-inspection and secondary path adjustment.

[0078] Specifically, in the embodiment, in the parametric equation of the helical trajectory Mathematical model of error in multi-start thread machining Compensation formula as well as In this context, X / Y / Z represent the three-dimensional coordinates for thread machining, d is the nominal diameter of the planetary roller screw, θ is the screw rotation angle, p is the screw thread lead, Z0 is the axial starting reference coordinate of the thread, ΔF(θ, Z) is the comprehensive error of thread machining, k1 is the rotation angle error weighting coefficient, Δθ is the axis rotation indexing error, k2 is the axial feed error weighting coefficient, ΔZ is the Z-axis axial feed error, k3 is the helix angle error weighting coefficient, Δβ is the thread helix angle machining error, ε is the system random residual (measurement noise), and Δθ_ 补 To compensate for the C-axis rotation angle, ΔZ_ 补 This is to compensate for the Z-axis axial feed.

[0079] Given X = 2dcosθ = 2 × 200 × cos3π = 400 × 0.5 = 200 mm, Y=2dsinθ=2×200×sin3π=400×23≈346.41mm, Z = 2πPθ + Z0 = 2 × π × 72 × 3π + 0 ≈ 473.74 mm and k1 2 +k2 2 +k3 2 =50 2 +10 2 +80 2 Taking 2500+100+6400=9000 as an example, the final calculation is: Δθ_ 补 ≈-5.56×10 5 tad, ΔZ_ 补 ≈-1.11×10 5 mm. Conclusion: By planning the probe detection path according to the corrected helical trajectory and after reverse compensation of the C-axis and Z-axis, the cumulative error of the multi-start thread pitch is ≤0.005mm / 1000mm (that is, within 1000mm, the cumulative error of the multi-start thread pitch is ≤0.005mm), and the indexing error is ≤0.001°, which meets the requirements of high-precision machining.

[0080] During operation, the precision monitoring module of the planetary roller screw external thread grinding machine can monitor the working data of the screw fixing module 2 and the grinding wheel module 3 in real time. The control system applies a quantitative mathematical model based on the collected data to achieve quantitative design and closed-loop compensation. This enables thermal symmetry and constant force thermal compensation for long-stroke machining, hydrostatic following flexible adaptive clamping of the center rest 204, collaborative dynamic compensation for grinding based on acoustic emission monitoring, thermal insulation and cooling structure design of the linear motor direct drive system, and in-situ probe detection and indexing error modeling and path compensation for multi-start threads. This ensures the stability and consistency of the machining process of the planetary roller screw external thread grinding machine, avoids the time-consuming offline detection process, and significantly improves machining efficiency.

[0081] Finally, it should be noted that the above-described embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The scope of protection of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the scope of the technology disclosed in this application. Such modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A planetary roller screw external thread grinding machine, characterized in that, The external thread grinding machine for planetary roller screws includes: The grinding machine body is provided with a lead screw slide and a grinding wheel slide that intersect perpendicularly. The lead screw slide extends along the linear axis Z and the grinding wheel slide extends along the linear axis X. A lead screw fixing module is movably disposed in the lead screw slide, the workpiece to be processed is fixed in the lead screw fixing module, and the lead screw fixing module can drive the workpiece to be processed to rotate around the rotation axis C; A grinding wheel module is movably disposed in the grinding wheel slideway. The grinding wheel module includes a turntable, a grinding wheel assembly, and a dressing assembly. The turntable can drive the grinding wheel assembly and the dressing assembly to rotate around the rotation axis A. The dressing assembly is adjustablely disposed on the upper part of the grinding wheel assembly. The precision monitoring module includes a grating ruler assembly, an acoustic emission sensor, a dynamic balancing instrument, a six-axis force sensor, and a probe assembly. The grating ruler assembly is disposed on the grinding machine body, the acoustic emission sensor and the dynamic balancing instrument are disposed on the grinding wheel module, and the probe assembly is disposed on the rotary table. The probe assembly includes a probe section that is oscillatingly disposed on the side of the grinding wheel assembly. The control system is connected to the precision monitoring module via signal transmission.

2. The external thread grinding machine for planetary roller screws according to claim 1, characterized in that, The dressing assembly includes a dressing shaft, a dressing wheel, and a cross slide assembly. The cross slide assembly includes a first slide and a second slide arranged perpendicularly to each other. The first slide extends along a linear axis Y, and the second slide extends along a linear axis W. The second slide is slidably disposed on the first slide. The dressing shaft is slidably disposed on the second slide. The dressing wheel is disposed at the end of the dressing shaft. The dressing wheel adjusts its contact position with the grinding wheel assembly through the cross slide assembly to dress the grinding wheel assembly. The grinding wheel assembly includes a grinding wheel body and a grinding wheel shaft. The grinding wheel body is disposed at the end of the grinding wheel shaft, and the grinding wheel shaft drives the grinding wheel body to rotate. The dynamic balancing instrument is disposed inside the grinding wheel shaft, and the acoustic emission sensor is disposed at the upper part of the grinding wheel shaft. The probe assembly further includes a transmission unit, which is mounted on the turntable via a mounting plate. The first end of the probe unit is a detection end, and the second end of the probe unit is pivotally connected to the transmission unit. When the planetary roller screw external thread grinding machine is working, the grinding wheel body processes the workpiece to be processed, the dressing wheel contacts the grinding wheel body, and after the workpiece to be processed is processed, the detection end of the probe part contacts the external thread of the workpiece to be processed.

3. The external thread grinding machine for planetary roller screws according to claim 2, characterized in that, The lead screw fixing module includes a worktable, a head clamping frame, a tail clamping frame, and at least one set of center frames. The head clamping frame, the tail clamping frame, and the center frames are all slidably mounted on the worktable via sliding seats. The rotation axis of the head clamping frame is the C-axis. The head clamping frame is positioned by a torque motor in conjunction with a circular grating. The tail clamping frame is a constant force adaptive thermal compensation tailstock. The six-axis force sensor is integrated into the tail clamping frame. The central frame includes a positioning body, a first pressure rod, a second pressure rod, and a third pressure rod. The first pressure rod, the second pressure rod, and the third pressure rod are sequentially arranged vertically on the positioning body. Both the first pressure rod and the third pressure rod include an arc-shaped clamping portion, a first pushing portion, and a first fixing portion. One end of the arc-shaped clamping portion extends out of the positioning body, and the other end of the arc-shaped clamping portion is arbitrarily connected to the positioning body via the first pushing portion. The first fixing portion passes through the arc-shaped clamping portion and the positioning body. The arc-shaped clamping portions of the pressure rod and the third pressure rod are symmetrically arranged to clamp the planetary roller screw respectively; the second pressure rod includes an abutting portion, a second pushing portion, and a second fixing portion. One end of the abutting portion passes through the positioning body and abuts against the planetary roller screw, and the other end of the abutting portion is connected to the second pushing portion. The second fixing portion passes through the abutting portion and the positioning body; the arc-shaped clamping portions of the first pressure rod, the abutting portion, and the arc-shaped clamping portions of the third pressure rod form a three-contact fixed-circle clamping structure around the workpiece to be processed; The grinding module also includes a grinding wheel slide plate and a grinding wheel pad plate disposed at the bottom of the turntable. The turntable is connected to the grinding wheel slide plate through the grinding wheel pad plate, and the grinding wheel slide plate is slidably connected to the grinding wheel slide. The grating ruler assembly includes a first grating ruler and a second grating ruler. The first grating ruler is disposed on the side of the worktable, and the second grating ruler is disposed on the side of the grinding wheel slide.

4. The external thread grinding machine for planetary roller screws according to claim 3, characterized in that, Both the lead screw slide and the grinding wheel slide are provided with U-shaped grooves, and a slide rail body is provided inside the U-shaped groove. Limiting components are provided at both ends of the slide rail body. Both the lead screw slide and the grinding wheel slide are equipped with a linear motor direct drive system. The linear motor direct drive system includes a linear motor and a magnetic plate. The linear motor is used to drive the lead screw fixing module and the grinding wheel grinding module. The magnetic plate is laid on the lead screw slide and the grinding wheel slide.

5. A design method for an external thread grinding machine for planetary roller screws, characterized in that, The design method for the external thread grinding machine for planetary roller screws is used to design the external thread grinding machine for planetary roller screws as described in claim 4. The design method for the external thread grinding machine for planetary roller screws includes: Thermal symmetry and constant force thermal compensation structure design for long-stroke machining; The central frame features a flexible, adaptive clamping design. Design of a collaborative dynamic compensation structure for grinding and repair based on acoustic emission monitoring; The thermal insulation and cooling structure design of the linear motor direct drive system; The probe part is used for in-situ detection and the indexing error modeling and path compensation design of multi-start threads.

6. The design method for an external thread grinding machine for planetary roller screws according to claim 5, characterized in that, The tail clamping frame is equipped with a retractable tip and a hydraulic telescopic mechanism. The retractable tip is connected to the tail clamping frame through the hydraulic telescopic mechanism. The six-axis force sensor is integrated at the end of the retractable tip. The six-axis force sensor is connected to the hydraulic telescopic mechanism and the control system. The control system calculates the axial elongation through a lead screw thermal expansion calculation model and adjusts the tip retraction amount ΔS in real time through an axial stress-retraction correlation model to maintain a constant clamping force. The thermal symmetry and constant force thermal compensation structure design for long-stroke machining includes the following steps: The axial elongation of the lead screw under different temperature rises is calculated using the thermal expansion calculation model of the lead screw. The retractable tip is designed as a hydraulically driven elastic structure, and an axial margin matching the elongation is reserved. The six-axis force sensor is integrated at the end of the retractable tip, the first temperature sensor is attached to the workpiece, and the first temperature sensor and the six-axis force sensor are respectively connected to the control system signal. The quantitative relationship between stress and tip relief is established through the axial stress-relief correlation model. A constant clamping force adaptive adjustment program is written into the control system, a threshold of clamping force is preset, and the tip relief amount is calculated and adjusted in real time based on the detection data and the axial stress-relief amount correlation model. The head clamp adopts a fixed-axis rotation design, so that the retractable tip of the head clamp and the tail clamp form a thermally symmetrical structure.

7. The design method for an external thread grinding machine for planetary roller screws according to claim 5, characterized in that, The central frame is a hydrostatic follow-type central frame, which is equipped with a hydrostatic support system. Oil holes are opened on the clamping surfaces of the arc-shaped clamping part and the abutment part. The hydrostatic support system includes an oil passage, which is connected to the oil holes to form an oil film of 5μm to 10μm. The central frame achieves non-contact flexible clamping based on the hydrostatic oil film pressure model and the oil film gap-clamping force correlation model. The flexible adaptive clamping design of the central frame includes the following steps: By using the hydrostatic oil film pressure model and the oil film gap-clamping force correlation model, the target oil film gap and oil supply pressure corresponding to different nominal screw diameters are calculated, and the core design parameters of the center frame clamping structure are determined. Based on the three-contact fixed circle clamping structure, the arc-shaped clamping part is made of engineering ceramic material, and oil holes are opened on the clamping surfaces of the arc-shaped clamping part and the abutment part, as well as a hydrostatic support system including an oil pump, oil circuit and pressure sensor. The sliding mating surface between the center frame and the worktable is designed as a hydrostatic guide rail structure. Connect the pressure sensor to the control system signal, establish the quantitative relationship between oil supply pressure and clamping force through the oil film gap-clamping force correlation model, and preset the clamping force threshold of a single clamping part; An adaptive oil film pressure adjustment program is written into the control system. Based on the detection data of the pressure sensor and the correlation model of the oil film gap-clamping force, the oil supply pressure of the oil pump is adjusted in real time to ensure that the oil film gap is stable between 5μm and 10μm.

8. The design method for an external thread grinding machine for planetary roller screws according to claim 5, characterized in that, The planetary roller screw external thread grinding machine is equipped with a grinding and repair collaborative dynamic compensation system. The grinding and repair collaborative dynamic compensation system includes a grinding wheel wear signal feature library and a cross slide assembly drive system. The acoustic emission sensor is signal-connected to the control system and the cross slide assembly drive system. The control system extracts feature values ​​through the acoustic emission signal effective value formula and stores them in the grinding wheel wear signal feature library. It also calculates the real-time wear amount based on the acoustic emission-grinding wheel wear amount fitting model and drives the cross slide assembly to feed. The design of the grinding and repair collaborative dynamic compensation structure based on acoustic emission monitoring includes the following steps: The acoustic emission sensor is integrated into the upper part of the grinding wheel shaft, so that the acoustic emission sensor forms a closed-loop signal connection with the control system and the cross slide assembly drive system, so as to collect the acoustic emission signal in real time, extract the feature value through the effective value formula, and store it in the grinding wheel wear signal feature library. The characteristic values ​​of the acoustic emission signal of the grinding wheel under different wear conditions and the actual wear amount were obtained through preliminary experiments. A univariate linear fitting algorithm was used to establish an acoustic emission-grinding wheel wear amount fitting model, which was then entered into the control system. The cross slide table feed linkage program is designed. The control system calculates the real-time wear of the grinding wheel body based on the real-time detected feature values ​​through the acoustic emission-grinding wheel wear fitting model, and drives the cross slide table assembly to make feed adjustments according to the feed formula. A closed-loop control system is implemented to monitor acoustic emission, calculate wear, and adjust feed, ensuring that the dressing amount of the dressing wheel is precisely matched with the grinding consumption of the grinding wheel body.

9. The design method for an external thread grinding machine for planetary roller screws according to claim 5, characterized in that, The linear motor direct drive system is equipped with the heat insulation and cooling structure, which includes a heat insulation pad, a cooling channel, a thermally isolated connector, and a heat insulation protective cover. The heat insulation pad is located between the U-shaped groove and the magnetic plate. The cooling channel is located on both sides of the U-shaped groove. The mover of the linear motor is connected to the moving parts by the thermally isolated connector. The heat insulation protective cover is installed on the grating ruler assembly. The stator of the linear motor is equipped with a second temperature sensor, which is connected to the control system. The control system realizes quantitative control of thermal deformation through the thermal deformation calculation model and the heat dissipation power calculation model of the linear motor, ensuring that the stator temperature rise of the linear motor is ≤5℃. The thermal insulation and cooling structured design of the linear motor direct drive system includes the following steps: The thermal deformation calculation model is used to calculate the stator thermal deformation of the linear motor under different temperature rises. Combined with the heat dissipation power calculation model, the heat dissipation power requirement of the thermal insulation and cooling structure is determined, and the structural design standards for thermal insulation, cooling and thermal isolation are defined. The heat insulation pad is provided between the U-shaped groove and the magnetic plate. Cooling channels extending along the length of the slide are opened on both sides of the U-shaped groove and connected to the water cooling system. The heat-isolated connector is installed between the mover and the moving part of the linear motor. The heat insulation protective cover is added to the grating ruler assembly. The second temperature sensor is attached to the stator of the linear motor, and the second temperature sensor is connected to the water cooling system through the control system signal to establish a quantitative relationship between the motor temperature rise and the coolant flow rate. A thermal deformation adaptive adjustment program is written into the control system. Based on the detection data of the second temperature sensor and the thermal deformation calculation model, the coolant flow rate of the water cooling system is adjusted in real time to ensure that the stator temperature rise of the linear motor is ≤5℃.

10. The design method for an external thread grinding machine for planetary roller screws according to claim 5, characterized in that, The planetary roller screw external thread grinding machine is equipped with a multi-start thread detection and compensation system. The multi-start thread detection and compensation system includes an error mathematical model. The probe part of the probe assembly is connected to the torque motor and the first grating ruler signal. The detection path of the probe part follows the parametric equation of the planetary roller screw helical trajectory. The control system uses a least squares fitting algorithm to establish the error mathematical model and performs reverse compensation for the C-axis and the Z-axis. The error mathematical model includes the indexing error of the C-axis, the feed error of the Z-axis, and the helix angle error. The multi-start thread detection and compensation system realizes pre-compensation and real-time compensation of machining errors. The in-situ detection of the probe and the modeling and path compensation design of the indexing error of the multi-start thread include the following steps: The probe assembly, the torque motor, and the first grating ruler are connected to the signal, the basic parameters of the workpiece to be processed are set, and the detection path of the probe part is planned by the spiral trajectory formula. Using the end face of the lead screw blank as a reference, the micron-level precise positioning of the starting point of the multi-start thread is achieved through the angular indexing of the C-axis and the axial positioning of the Z-axis, and the coordinates of each starting point position are recorded. After single-start thread grinding, the probe is used to detect along the helical trajectory and extract pitch and indexing error data. The least squares fitting algorithm is used to establish the error mathematical model for multi-start thread machining, which includes the indexing error of the C-axis, the feed error of the Z-axis, and the helix angle error. The linkage path compensation program is designed to calculate the compensation amount in real time based on the error mathematical model, and to perform pre-compensation and real-time compensation for subsequent thread head processing. After the full stroke processing, the probe part is used for re-inspection and secondary path adjustment.

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