Automatic detection and adjustment machine tool tailstock and automatic detection and adjustment method

Abstract

The application discloses a machine tool tailstock capable of automatically detecting and adjusting top pressure and an automatic detecting and adjusting method, and belongs to the technical field of machine tools. An axial sliding assembly of a tailstock sleeve is arranged in a seat body of the machine tool tailstock. A rotary center is arranged at the front end of the tailstock sleeve. A lead screw is coaxially arranged in the tailstock sleeve. A slide is arranged at the front end of a lead screw nut of the lead screw. The slide is slidably arranged on a guide rod at the rear end of the tailstock sleeve. A compression spring is arranged outside the lead screw nut. The front and rear ends of the compression spring are respectively abutted against the tailstock sleeve and the flange end surface of the lead screw nut. The lead screw is rotatably arranged in a bearing seat through a bearing. A cooling structure is arranged on the bearing seat. An axial light transmission hole is arranged on the lead screw nut. Two laser distance sensors are arranged on the bearing seat. One of the two laser distance sensors is arranged to pass through the light transmission hole and is aligned with the rear end of the tailstock sleeve. The other laser distance sensor is arranged to the rear end of the lead screw nut. A limiting structure is arranged between the seat body and the tailstock sleeve to limit the circumferential rotation. The rear end of the lead screw is connected with a driving assembly. The application can automatically adjust the top pressure and is suitable for hot working conditions.

Description

Technical Field

[0001] This invention relates to the field of machine tool technology, specifically to a tailstock of a machine tool with automatic clamping force detection and adjustment, and an automatic detection and adjustment method. Background Technology

[0002] Machine tool tailstocks are used to apply clamping force from the end of the workpiece during the machining of shaft parts to ensure clamping reliability. Existing tailstocks are mainly divided into two types: hydraulically driven and servo-driven.

[0003] CN206263279U discloses a hydraulic tailstock system for machine tools, which employs a hydraulic tailstock. A piston rod is driven by a hydraulic chamber, and the hydraulic pressure is transmitted to the center seat via a spring-loaded rod. A displacement sensor detects the spring compression to indirectly reflect the clamping force. This system relies on a hydraulic system to maintain constant pressure; however, the hydraulic oil is susceptible to pressure fluctuations due to temperature variations, leading to unstable clamping force. Furthermore, the hydraulic cylinder seals are prone to aging and failure under high-temperature conditions, posing a risk of oil leakage and resulting in low reliability.

[0004] CN120079901A discloses a programmable servo torque tailstock, which uses a servo-driven tailstock and a laser rangefinder to achieve closed-loop control of the tailstock position and torque. However, the laser rangefinder is used to detect the distance between the center and the workpiece top groove and the length of the tailstock cavity. Its purpose is to judge the docking accuracy and clamping stability. It does not involve the direct detection and closed-loop adjustment of the clamping force. It cannot automatically absorb the deformation when the workpiece is heated and expands, which can easily cause the workpiece to be squeezed and deformed. It also does not consider the impact of high processing temperature on the laser rangefinder and servo motor.

[0005] In summary, the existing machine tool tailstock technology suffers from problems such as the inability to adaptively adjust the clamping force and poor adaptability to high-temperature working conditions, making it difficult to meet the requirements of high-precision and high-stability hot processing production. Summary of the Invention

[0006] To address the problems of existing machine tool tailstocks having unadaptable clamping force and poor adaptability to high-temperature conditions, thus failing to meet the requirements of high-precision and high-stability hot processing production, this invention provides a machine tool tailstock with automatic clamping force detection and adjustment, and an automatic detection and adjustment method.

[0007] To achieve the above objectives, the technical solution adopted by the tailstock of the automatic clamping force detection and adjustment machine tool in this invention is as follows: A tailstock for an automatic clamping force detection and adjustment machine tool includes a base body with a cylindrical cavity extending through both ends. A center sleeve is axially slidably fitted within the cylindrical cavity. The front end of the center sleeve extends out of the base body and is fitted with a rotating center. A lead screw is coaxially mounted inside the center sleeve, with its rear end extending out of the base body. A lead screw nut is mounted on the lead screw. A guide rod extending axially is located at the rear end of the center sleeve. An annular slide block is fixedly mounted at the front end of the lead screw nut, and the slide block slidably fits onto the guide rod. A compression spring is fitted around the outer periphery of the lead screw nut, with its front end abutting against the center sleeve and its rear end abutting against the flange end face of the lead screw nut. The lead screw... The bearing is rotatably mounted in a bearing housing, which is installed in the rear opening of the base body. The bearing housing is equipped with a cooling structure. The lead screw nut has an axially penetrating light-transmitting hole. A first laser rangefinder and a second laser rangefinder are mounted on the bearing housing. The detection optical path of the first laser rangefinder passes through the light-transmitting hole and is aligned with the rear end of the center sleeve. The detection optical path of the second laser rangefinder is aligned with the rear end of the lead screw nut. A limiting structure is provided between the base body and the center sleeve to restrict the circumferential rotation of the center sleeve. The rear end of the lead screw extends out of the base body and is connected to the drive assembly. The drive assembly can drive the lead screw to rotate around its own axis.

[0008] This invention utilizes a compression spring between the lead screw nut and the center sleeve to form an elastic clamping structure. When the workpiece expands axially due to heat, the center sleeve compresses the spring and retracts, automatically absorbing the thermal expansion and preventing workpiece bending deformation caused by rigid clamping. To achieve automatic detection and adaptive adjustment, this invention employs a first laser rangefinder to detect the rear displacement of the center sleeve and a second laser rangefinder to detect the rear displacement of the lead screw nut. The difference between these two values ​​can be calculated to directly determine the actual compression of the spring, which is then converted into the clamping force. The detection optical path does not contact the object being measured, avoiding zero drift and damage to the pressure sensor due to high temperature and vibration. Simultaneously, the cooling structure on the bearing housing provides forced cooling of the bearing and surrounding components, reducing the risk of high processing temperatures being transferred to the laser rangefinder and lead screw. The limiting structure in this invention constrains the center sleeve, allowing it to slide only axially, ensuring that the rotating center always rotates around its own axis, resulting in a stable clamping posture.

[0009] Preferably, the rear end of the center sleeve has a groove, the guide rod is located in the groove, and a retaining ring is fixedly provided on the end face of the rear end of the center sleeve. The front end of the lead screw nut passes through the retaining ring. The retaining ring and the slide block are respectively provided with holes for the guide rod to pass through. The slide block is located in the groove, and the front end of the compression spring abuts against the rear end face of the retaining ring. The detection optical path of the first laser rangefinder passes through the light-transmitting hole and is aligned with the rear end face of the retaining ring. By opening a groove at the rear end of the center sleeve and integrating components such as the slide block and the compression spring into the groove, the clamping force detection and adjustment structure is highly compact in the axial direction, shortening the overall axial length of the tailstock. The retaining ring, as the front abutment of the compression spring and the detection target surface of the first laser rangefinder, simultaneously undertakes the functions of compression spring support and range reflection, reducing the number of parts. The guide rod passes through the corresponding holes on the retaining ring and the slide block, ensuring the coaxiality of the lead screw nut and the center sleeve, which is beneficial for uniform force on the compression spring and no deviation in the compression direction.

[0010] Preferably, the cooling structure includes cooling water channels formed on the bearing housing, with an annular water-cooling cover plate on the outer side of the bearing housing. The water-cooling cover plate can seal the cooling water channels and has an inlet and a return water connector. The cooling water channels formed on the bearing housing and sealed by the water-cooling cover plate constitute an internal liquid cooling channel, which is compact and does not increase the risk of interference from external pipelines. The coolant is introduced through the inlet connector and discharged through the return water connector, which can continuously remove the frictional heat of the bearing and the radiant heat of the workpiece conducted from the housing during processing, keeping the operating environment temperature of the bearing housing and the laser rangefinder sensor mounted on it within a stable range, reducing the impact of temperature changes on the accuracy of laser ranging.

[0011] Preferably, the limiting structure includes an axial guide groove formed on the outer wall of the center sleeve, and a guide screw on the base that passes through a cylindrical cavity along the radial direction of the center sleeve, with the end of the guide screw extending into the axial guide groove. The end of the guide screw extending into the axial guide groove on the outer wall of the center sleeve forms a mechanical anti-rotation constraint. The limiting structure is simple and reliable, restricting only the circumferential degree of freedom and not affecting the axial forward and backward sliding of the center sleeve. It can maintain a stable anti-rotation effect during long-term reciprocating motion, preventing the center sleeve from deflecting due to cutting torque and ensuring that the axis of the rotating center is always coaxial with the machine tool spindle.

[0012] Preferably, the drive assembly includes a coupling, a reducer, and a servo motor. The output end of the servo motor is connected to the input end of the reducer, and the output end of the reducer is connected to the rear end of the lead screw via the coupling. The servo motor, after its torque is amplified by the reducer, drives the lead screw to rotate through the coupling, resulting in simple transmission and fast response. The output torque and speed of the servo motor can be precisely controlled, allowing for digital setting of the feed amount and feed speed of the lead screw nut, providing an execution basis for quantitative closed-loop adjustment of the clamping force. The reducer also amplifies the holding torque, which helps resist axial impact forces generated during workpiece machining.

[0013] Preferably, a U-shaped mounting bracket is fixedly provided at the rear end of the base, the coupling is located within the U-shaped space of the U-shaped mounting bracket, the reducer housing is fixedly mounted on the U-shaped mounting bracket, and the output end of the reducer passes through the middle connecting plate of the U-shaped mounting bracket. The U-shaped mounting bracket accommodates the coupling within its U-shaped space, reducing the probability of foreign objects intruding into the working area of ​​the coupling. The reducer output end directly connects to the coupling through the middle connecting plate of the U-shaped mounting bracket, shortening the overhang length of the transmission chain and improving the accuracy of rotary transmission.

[0014] Preferably, the lead screw and the lead screw nut are both trapezoidal. The trapezoidal lead screw and nut have self-locking characteristics. When the servo motor stops supplying power, the lead screw pair can maintain its current position, preventing the rotating center from accidentally retracting under machining vibration or external force. Furthermore, compared to ordinary transmission lead screws, trapezoidal lead screws have a larger contact area under the same axial load, resulting in better wear resistance and making them suitable for long-term, frequent advance and retreat of the tailstock.

[0015] Preferably, one or more guide rods are provided, and the multiple guide rods are evenly distributed around the circumference of the center sleeve. The even distribution of multiple guide rods around the circumference ensures balanced force distribution when the slide block slides on the guide rods, avoiding unilateral load that could cause slide block jamming or uneven sliding resistance. In a scheme with only one guide rod, the guide rod and the lead screw together form a two-point guiding constraint, resulting in a simpler structure. In a scheme with multiple guide rods, the guiding redundancy is increased, and even if individual guide rods wear, the axial movement trajectory of the slide block can still be effectively constrained.

[0016] Preferably, the outer ring of the bearing is fixed to the bearing housing by a bearing cap, which is located at the front end of the bearing housing. A bearing retaining ring and a lock nut are fitted around the outside of the lead screw. The bearing retaining ring and lock nut are located at the end of the bearing furthest from the bearing cap. The bearing retaining ring is positioned between the bearing and the lock nut, with its front end abutting against the rear end of the inner ring of the bearing, and its rear end abutting against the front end of the lock nut. The bearing cap fixes the outer ring of the bearing, and the bearing retaining ring and lock nut cooperate to fix the inner ring of the bearing, forming a bidirectional axial positioning structure at the rear end of the lead screw. This structure can control the axial movement of the lead screw within the bearing clearance range, which helps maintain the engagement accuracy of the lead screw and lead screw nut and avoids fluctuations in the spring compression detection value caused by axial movement.

[0017] The technical solution adopted in the automatic detection, adjustment and control method for tightening force in this invention is as follows: An automatic detection and adjustment control method for the clamping force of a machine tool tailstock, employing any one of the above-mentioned methods, comprises the following steps: S1. Initialize control system parameters: The material shear modulus of the compression spring is set in the control system. wire diameter Median diameter Valid number of laps Free state height Flange thickness of lead screw nut Tightening force sampling cycle The origin and limit travel positions of the rotary tip; S2. Calculate the maximum static friction force of the center sleeve. : Start the manual clamping program in the control system, control the drive component to drive the lead screw to rotate, thereby driving the lead screw nut forward and compressing the compression spring. After the compression spring pushes the center sleeve forward any distance, stop the operation of the drive component. Read the measurement value from the first laser rangefinder sensor. The measured values ​​of the second laser rangefinder sensor Calculate the pressure value of the compression spring. The pressure value of the compression spring Set as the maximum static friction force of the center sleeve The pressure value of the compression spring The calculation formula is:

[0018]

[0019] S3. Set the workpiece clamping force parameters: Set the target clamping force according to the material and size of the workpiece. and the allowable fluctuation threshold of the tightening force ; S4. Clamping the workpiece: Move the machine tool tailstock to a suitable position relative to the workpiece, and start the automatic clamping force detection and adjustment program in the control system. The control system will adjust the clamping force according to the target clamping force. The control drive component drives the center sleeve forward, which in turn drives the rotary center to feed and clamp the workpiece. During this process, the control system uses a preset clamping force sampling period. Continuously collect the measurement values ​​from the first laser rangefinder sensor. The measured values ​​of the second laser rangefinder sensor And based on the measurement value of the first laser rangefinder sensor The measured values ​​of the second laser rangefinder sensor Calculate the actual clamping force ,when At this time, the drive component stops moving, and the actual clamping force... The calculation formula is:

[0020] S5. Automatic detection and adjustment of clamping force during workpiece processing: During workpiece processing, the workpiece expands due to heat, further compressing the spring and increasing the actual clamping force. The force gradually increases, and the control system samples the force at a preset interval. Continuously collect the measurement values ​​from the first laser rangefinder sensor. The measured values ​​of the second laser rangefinder sensor And based on the measurement value of the first laser rangefinder sensor The measured values ​​of the second laser rangefinder sensor Calculate the actual clamping force ,when At that time, the control system automatically outputs an adjustment signal, controlling the drive component to drive the rotary center backward until... Stop at this time; S6. Processing completed: After processing is completed, the control system controls the drive assembly to drive the rotary center back to the set origin position, and the processed workpiece is removed.

[0021] This method calculates the maximum static friction force of the center sleeve separately using a manual tightening procedure before tightening the workpiece. The maximum static friction value This is stored as a system constant in the control system, and then applied to the actual tightening force in subsequent operations. This force is deducted from the calculation, ensuring that the control system receives the actual clamping force on the workpiece rather than the total pressure of the compression springs, thus improving the accuracy of force calculation. A fixed sampling period is used during the processing. Continuous monitoring of actual tightening force and in The servo motor actively drives the rotating center to retract and relieve pressure, realizing the dynamic maintenance of the clamping force throughout the entire processing process. It can cope with pressure fluctuations caused by the thermal expansion of the workpiece without manual intervention.

[0022] The beneficial effects of this invention include: 1. The present invention forms an elastic clamping structure by setting a compression spring between the lead screw nut and the center sleeve. When the workpiece expands axially due to heat, the center sleeve can compress the compression spring and retract, automatically absorbing the thermal expansion and avoiding rigid clamping that causes the workpiece to bend and deform.

[0023] 2. In order to achieve automatic detection and adaptive adjustment, the present invention uses a first laser rangefinder to detect the displacement of the rear end of the top sleeve and a second laser rangefinder to detect the displacement of the rear end of the lead screw nut. The difference between the two can be calculated to directly obtain the actual compression of the spring, and then converted into the tightening force value. There is no contact between the detection optical path and the object being measured, which avoids the problem of zero drift and damage to the pressure sensor caused by high temperature and vibration.

[0024] 3. The cooling structure provided on the bearing housing of the present invention can provide forced cooling for the bearing and surrounding components, reducing the risk of high processing temperatures being transferred to the laser rangefinder and lead screw.

[0025] 4. The limiting structure in this invention can constrain the center sleeve, making it slide only axially, ensuring that the rotating center always rotates around its own axis and the clamping posture is stable. Attached Figure Description

[0026] To more clearly illustrate the technical solution of this patent, the drawings used in the description will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this patent. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 This is a three-dimensional structural diagram of a tailstock of a machine tool with automatic clamping force detection and adjustment according to a specific embodiment of the present invention; Figure 2 for Figure 1 Sectional view of AA; Figure 3 for Figure 2 BB section view; Figure 4 for Figure 2 CC section view; Figure 5 This is a perspective view of a partial structure of the tailstock of a machine tool with automatic clamping force detection and adjustment according to a specific embodiment of the present invention.

[0028] Explanation of reference numerals in the attached figures: 1. Base; 2. Center sleeve; 201. Axial guide groove; 3. Rotary center; 4. U-shaped mounting bracket; 5. Coupling; 6. Reducer; 7. Servo motor; 8. Bearing housing; 801. Cooling water channel; 9. Water-cooled cover plate; 10. First laser rangefinder; 11. Second laser rangefinder; 12. Water inlet connector; 13. Water return connector; 14. Guide screw; 15. Lead screw; 16. Slide; 17. Retaining ring; 18. Compression spring; 19. Lead screw nut; 1901. Light-transmitting hole; 20. Guide rod; 21. Bearing cover; 22. Bearing; 23. Bearing retaining ring; 24. Locking nut. Detailed Implementation

[0029] To make the objectives, features, and advantages of this patent more apparent and understandable, the technical solutions of this patent will be clearly and completely described below with reference to the accompanying drawings of the specific embodiments. Obviously, the embodiments described below are only some embodiments of this patent, and not all embodiments. Based on the embodiments of this patent, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this patent.

[0030] Reference Figure 1-2 This embodiment proposes a tailstock for an automatic clamping force detection and adjustment machine tool, including a base 1. The base 1 is generally rectangular, with chamfered edges on its top two sides. A bolt-fixed base is connected to the bottom of the base 1. (Refer to...) Figure 3-4 The base 1 has a cylindrical cavity with two through ends. A center sleeve 2 is axially slidably fitted inside the cylindrical cavity. The front end of the center sleeve 2 extends out of the base 1 and is fitted with a rotating center 3. A lead screw 15 is coaxially provided inside the center sleeve 2. The rear end of the lead screw 15 extends out of the base 1 along the cylindrical cavity.

[0031] Reference Figure 4-5 A screw nut 19 is installed on the screw 15. A groove is provided at the rear end of the center sleeve 2. A guide rod 20 extending axially is provided in the groove. The front end of the guide rod 20 is fixedly inserted into the groove of the center sleeve 2. An annular slide block 16 is fixedly provided at the front end of the screw nut 19. The screw 15 passes through the middle of the slide block 16. A retaining ring 17 is fixedly provided on the annular end face of the rear end of the center sleeve 2. The inner diameter of the retaining ring 17 is slightly larger than the outer diameter of the front end of the screw nut 19. The front end of the screw nut 19 passes through the retaining ring 17. The retaining ring 17 and the slide block 16 are respectively provided with holes for the guide rod 20 to pass through. The slide block 16 is slidably sleeved on the guide rod 20 through the corresponding holes. The slide block 16 is located in the groove. A compression spring 18 is sleeved on the outer periphery of the screw nut 19. The front end of the compression spring 18 abuts against the rear end face of the retaining ring 17, and the rear end of the compression spring 18 abuts against the flange end face of the screw nut 19. Thus, the compression spring 18 is constrained between the retaining ring 17 and the flange end face of the lead screw nut 19. When the center sleeve 2 is pushed back by the workpiece, the retaining ring 17 compresses the compression spring 18. The amount of compression of the compression spring 18 is the relative displacement between the retaining ring 17 and the flange end face of the lead screw nut 19. The clamping force can be calculated by measuring this displacement. The guide rod 20 passes through both the slide 16 and the retaining ring 17, ensuring that the slide 16 remains coaxial with the center sleeve 2 during axial sliding. This prevents the compression spring 18 from undergoing uneven compression due to off-center loading and ensures that the compression direction of the compression spring 18 is consistent with the axis of the center sleeve 2.

[0032] Reference Figure 4-5The lead screw 15 is rotatably mounted in the bearing housing 8 via the bearing 22, and the bearing housing 8 is installed in the rear opening of the housing 1. The outer ring of bearing 22 is fixed to bearing housing 8 by bearing cover 21, which is located at the front end of bearing housing 8. A bearing retaining ring 23 and a locking nut 24 are sleeved on the outside of lead screw 15. The bearing retaining ring 23 and locking nut 24 are located at the end of bearing 22 away from bearing cover 21. The bearing retaining ring 23 is located between bearing 22 and locking nut 24. The front end of bearing retaining ring 23 abuts against the rear end of inner ring of bearing 22, and the rear end of bearing retaining ring 23 abuts against the front end of locking nut 24. Through the cooperation of bearing cover 21, bearing retaining ring 23 and locking nut 24, bidirectional axial positioning of the rear end of lead screw 15 is achieved, and the axial movement of lead screw 15 is controlled within the clearance range of bearing 22. This helps to maintain the engagement accuracy of lead screw 15 and lead screw nut 19 and avoid fluctuations in the compression detection value of spring 18 caused by axial movement.

[0033] The bearing housing 8 is equipped with a cooling structure, which includes a cooling water channel 801 formed on the bearing housing 8. The cooling water channel 801 can be an annular groove formed on the outer end face of the bearing housing 8. The outer side of the bearing housing 8 is equipped with an annular water-cooling cover plate 9, which can close the cooling water channel 801. The water-cooling cover plate 9 is equipped with a water inlet connector 12 and a water return connector 13. The coolant is introduced into the cooling water channel 801 through the water inlet connector 12 and discharged through the water return connector 13. During the processing, it continuously removes the frictional heat of the bearing 22 and the radiant heat of the workpiece conducted from the housing 1, so that the working environment temperature of the bearing housing 8 and the laser rangefinder sensor installed on it is maintained within a stable range, reducing the impact of temperature changes on the laser rangefinder accuracy, and avoiding thermal deformation caused by high temperature being transferred to the lead screw 15 and lead screw nut 19.

[0034] A through-hole 1901 is provided on the flange of the lead screw nut 19. A first laser rangefinder 10 and a second laser rangefinder 11 are mounted on the bearing housing 8, both penetrating the bearing housing 8. The detection optical path of the first laser rangefinder 10 passes through the through-hole 1901 and is aligned with the rear end face of the retaining ring 17 at the rear end of the center sleeve 2 to detect the distance between it and the retaining ring 17. The detection optical path of the second laser rangefinder 11 is aligned with the rear end face of the lead screw nut 19 to detect the distance between it and the rear end face of the lead screw nut 19. Both laser rangefinders are fixed on the bearing housing 8 and have the same measurement reference. By subtracting the distance value measured by the first laser rangefinder 10 from the distance value measured by the second laser rangefinder 11, the sensor reference drift caused by temperature changes or assembly errors can be eliminated, the actual compression of the compression spring 18 can be obtained, and the tightening force can be calculated. The measurement method in this embodiment is non-contact detection, which avoids the problems of zero drift and damage to pressure sensors caused by high temperature and vibration.

[0035] Reference Figure 3 A limiting structure is provided between the base 1 and the center sleeve 2. The limiting structure includes an axial guide groove 201 formed on the outer wall of the center sleeve 2. The base 1 is provided with a guide screw 14 that passes through the cylindrical cavity along the radial direction of the center sleeve 2. The end of the guide screw 14 extends into the axial guide groove 201. The cooperation between the guide screw 14 and the axial guide groove 201 only restricts the circumferential rotation of the center sleeve 2, but does not restrict its axial forward and backward sliding. This ensures that the rotating center 3 always rotates around its own axis during the machining process without deflection, while allowing the center sleeve 2 to freely retract to absorb deformation when the workpiece thermally expands.

[0036] Reference Figure 1 and Figure 3 The rear end of the lead screw 15 extends out of the base 1 and connects to the drive assembly, which drives the lead screw 15 to rotate around its own axis. The drive assembly includes a coupling 5, a reducer 6, and a servo motor 7. The output end of the servo motor 7 is connected to the input end of the reducer 6, and the housing of the servo motor 7 is fixedly connected to the housing of the reducer 6 by bolts. The output end of the reducer 6 is connected to the rear end of the lead screw 15 through the coupling 5. The torque of the servo motor 7 is amplified by the reducer 6 and then transmitted to the lead screw 15. The transmission chain is simple and the response speed is fast. The output torque and speed of the servo motor 7 can be precisely controlled, allowing the feed amount and feed speed of the lead screw nut 19 to be digitally set, providing an execution basis for realizing quantitative closed-loop adjustment of the tightening force. A U-shaped mounting bracket 4 is fixedly provided at the rear end of the base 1. The coupling 5 is located in the U-shaped space of the U-shaped mounting bracket 4. The housing of the reducer 6 is fixedly mounted on the U-shaped mounting bracket 4, and the output end of the reducer 6 passes through the middle connecting plate of the U-shaped mounting bracket 4. The U-shaped mounting bracket 4 houses the coupling 5 within its U-shaped space, providing radial protection for the connection structure between the reducer 6, coupling 5, and the rear end of the lead screw 15, reducing the probability of foreign objects intruding into the working area of ​​the coupling 5. The lead screw 15 is a trapezoidal lead screw, and the lead screw nut 19 is also a trapezoidal lead screw nut. The trapezoidal lead screw pair has a self-locking characteristic, maintaining its current position when the servo motor 7 stops supplying power, preventing the center from accidentally retracting under processing vibration or external force. Compared to ordinary transmission lead screws 15, the trapezoidal lead screw has a larger contact area under the same axial load, better wear resistance, and is suitable for long-term, frequent advance and retreat of the tailstock. One or more guide rods 20 are provided, evenly arranged around the circumference of the center sleeve 2, ensuring balanced force on the slide 16 when sliding on the guide rods 20, avoiding unilateral load causing the slide 16 to jam or uneven sliding resistance.

[0037] Reference Figure 4The outer ring of bearing 22 is fixed to bearing housing 8 by bearing cover 21, which is located at the front end of bearing housing 8. A bearing retaining ring 23 and a locking nut 24 are sleeved on the outside of lead screw 15. The bearing retaining ring 23 and the locking nut 24 are located at the end of bearing 22 away from bearing cover 21. The bearing retaining ring 23 is located between bearing 22 and locking nut 24. The front end of bearing retaining ring 23 abuts against the rear end of inner ring of bearing 22, and the rear end of bearing retaining ring 23 abuts against the front end of locking nut 24.

[0038] This embodiment also proposes an automatic detection, adjustment, and control method for the clamping force of a machine tool tailstock, applicable to the aforementioned automatic clamping force detection and adjustment method for a machine tool tailstock, which includes the following steps: S1. Initialize control system parameters: The material shear modulus of the compression spring 18 is set in the control system. wire diameter Median diameter Valid number of laps Free state height Flange thickness of lead screw nut 19 Tightening force sampling cycle The origin and limit travel positions of the slewing tip 3; S2, Calculate the maximum static friction force of the center sleeve 2. : Start the manual clamping program in the control system, control the drive component to drive the lead screw 15 to rotate, thereby driving the lead screw nut 19 forward and compressing the compression spring 18. After the compression spring 18 pushes the center sleeve 2 forward any distance, stop the operation of the drive component. Read the measurement value of the first laser rangefinder 10 The measured value of the second laser rangefinder 11 Calculate the pressure value of spring 18. The pressure value of spring 18 Set as the maximum static friction force of the center sleeve 2 ; Pressure value of spring 18 The calculation formula is:

[0039]

[0040] S3. Set the workpiece clamping force parameters: Set the target clamping force according to the material and size of the workpiece. and the allowable fluctuation threshold of the tightening force ; S4. Clamping the workpiece: Move the machine tool tailstock to a suitable position relative to the workpiece, and start the automatic clamping force detection and adjustment program in the control system. The control system will adjust the clamping force according to the target clamping force. The control drive component drives the center sleeve 2 forward, which in turn drives the rotary center 3 to feed and clamp the workpiece. During this process, the control system uses a preset clamping force sampling period. Continuously collect the measurement values ​​of the first laser rangefinder sensor 10 The measured value of the second laser rangefinder 11 And based on the measurement value of the first laser rangefinder 10 The measured value of the second laser rangefinder 11 Calculate the actual clamping force ,when At this time, the drive component stops moving, and the actual clamping force... The calculation formula is:

[0041] S5. Automatic detection and adjustment of clamping force during workpiece processing: During the workpiece machining process, the workpiece expands due to heat, and the compression spring 18 is further compressed, increasing the actual clamping force. The force gradually increases, and the control system samples the force at a preset interval. Continuously collect the measurement values ​​of the first laser rangefinder sensor 10 The measured value of the second laser rangefinder 11 And based on the measurement value of the first laser rangefinder 10 The measured value of the second laser rangefinder 11 Calculate the actual clamping force ,when At that time, the control system automatically outputs an adjustment signal, controlling the drive component to drive the rotary tip 3 backward until... Stop at this time; S6. Processing completed: After processing is completed, the control system controls the drive assembly to drive the rotary center 3 back to the set origin position, and removes the processed workpiece.

[0042] The above description of the disclosed embodiments enables those skilled in the art to implement or use this patent. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this patent. Therefore, this patent is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A tailstock for an automatic clamping force detection and adjustment machine tool, comprising a base body (1), wherein the base body (1) has a cylindrical cavity with two through ends, and a center sleeve (2) is axially slidably mounted in the cylindrical cavity, the front end of the center sleeve (2) extending out of the base body (1) and fitted with a rotating center (3), characterized in that, A lead screw (15) is coaxially mounted inside the center sleeve (2). The rear end of the lead screw (15) extends out of the seat body (1). A lead screw nut (19) is mounted on the lead screw (15). A guide rod (20) extending axially is provided at the rear end of the center sleeve (2). An annular slide (16) is fixed at the front end of the lead screw nut (19). The slide (16) is slidably mounted on the guide rod (20). A compression spring (18) is sleeved on the outer periphery of the lead screw nut (19). The front end of the compression spring (18) abuts against the center sleeve (2), and the rear end of the compression spring (18) abuts against the flange end face of the lead screw nut (19). The lead screw (15) is rotatably mounted in the bearing seat (8) through the bearing (22). The bearing seat (8) is installed in the rear end opening of the seat body (1). A cooling structure is provided on the bearing seat (8); an axially penetrating light hole (1901) is provided on the lead screw nut (19); a first laser rangefinder (10) and a second laser rangefinder (11) are installed on the bearing seat (8); the detection light path of the first laser rangefinder (10) passes through the light hole (1901) and is aligned with the rear end of the top sleeve (2); the detection light path of the second laser rangefinder (11) is aligned with the rear end of the lead screw nut (19); a limiting structure is provided between the seat body (1) and the top sleeve (2); the limiting structure is used to limit the circumferential rotation of the top sleeve (2); the rear end of the lead screw (15) extends out of the seat body (1) and is connected to the drive assembly; the drive assembly can drive the lead screw (15) to rotate around its own axis.

2. The tailstock of a machine tool with automatic clamping force detection and adjustment according to claim 1, characterized in that, The rear end of the top sleeve (2) is provided with a groove, the guide rod (20) is located in the groove, and the end face of the rear end of the top sleeve (2) is fixedly provided with a retaining ring (17). The front end of the lead screw nut (19) passes through the retaining ring (17). The retaining ring (17) and the slide (16) are respectively provided with holes for the guide rod (20) to pass through. The slide (16) is located in the groove, and the front end of the compression spring (18) abuts against the rear end face of the retaining ring (17). The detection optical path of the first laser ranging sensor (10) passes through the light-transmitting hole (1901) and is aligned with the rear end face of the retaining ring (17).

3. The tailstock of a machine tool with automatic clamping force detection and adjustment according to claim 1, characterized in that, The cooling structure includes a cooling water passage (801) opened on the bearing housing (8), and an annular water-cooled cover plate (9) is provided on the outside of the bearing housing (8). The water-cooled cover plate (9) can close the cooling water passage (801). The water-cooled cover plate (9) is provided with an inlet connector (12) and a return connector (13).

4. The tailstock of a machine tool with automatic clamping force detection and adjustment according to claim 1, characterized in that, The limiting structure includes an axial guide groove (201) opened on the outer wall of the top sleeve (2), and a guide screw (14) on the seat (1) that passes through the cylindrical cavity along the radial direction of the top sleeve (2), with the end of the guide screw (14) extending into the axial guide groove (201).

5. The tailstock of a machine tool with automatic clamping force detection and adjustment according to claim 1, characterized in that, The drive assembly includes a coupling (5), a reducer (6) and a servo motor (7). The output end of the servo motor (7) is connected to the input end of the reducer (6), and the output end of the reducer (6) is connected to the rear end of the lead screw (15) through the coupling (5).

6. The tailstock of a machine tool with automatic clamping force detection and adjustment according to claim 5, characterized in that, The rear end of the base (1) is fixedly provided with a U-shaped mounting bracket (4), the coupling (5) is located in the U-shaped space of the U-shaped mounting bracket (4), the housing of the reducer (6) is fixedly installed on the U-shaped mounting bracket (4), and the output end of the reducer (6) passes through the middle connecting plate of the U-shaped mounting bracket (4).

7. The tailstock of a machine tool with automatic clamping force detection and adjustment according to claim 1, characterized in that, The lead screw (15) is a trapezoidal lead screw, and the lead screw nut (19) is a trapezoidal lead screw nut.

8. A tailstock for an automatic clamping force detection and adjustment machine tool according to any one of claims 1 or 2, characterized in that, There are one or more guide rods (20), and the multiple guide rods (20) are evenly arranged around the circumferential direction of the top sleeve (2).

9. The tailstock of a machine tool with automatic clamping force detection and adjustment according to claim 1, characterized in that, The outer ring of the bearing (22) is fixed to the bearing housing (8) by the bearing cover (21), and the bearing cover (21) is located at the front end of the bearing housing (8); the lead screw (15) is fitted with a bearing retainer (23) and a locking nut (24), the bearing retainer (23) and the locking nut (24) are located at the end of the bearing (22) away from the bearing cover (21), the bearing retainer (23) is located between the bearing (22) and the locking nut (24), the front end of the bearing retainer (23) abuts against the rear end of the inner ring of the bearing (22), and the rear end of the bearing retainer (23) abuts against the front end of the locking nut (24).

10. A method for automatically detecting and adjusting the clamping force of a machine tool tailstock as described in any one of claims 1 to 9, characterized in that, Includes the following steps: S1. Initialize control system parameters: The material shear modulus of the compression spring (18) is set in the control system. wire diameter Median diameter Valid number of laps Free state height Flange thickness of lead screw nut (19) Tightening force sampling cycle The origin and limit travel positions of the rotary tip (3); S2. Calculate the maximum static friction force of the center sleeve (2). : Start the manual clamping program in the control system, control the drive assembly to drive the lead screw (15) to rotate, thereby driving the lead screw nut (19) forward and compressing the compression spring (18). After the compression spring (18) pushes the center sleeve (2) forward any distance, stop the operation of the drive assembly; Read the measurement value from the first laser rangefinder (10). The measured values ​​of the second laser ranging sensor (11) Calculate the pressure value of the compression spring (18). The pressure value of the compression spring (18) Set as the maximum static friction force of the center sleeve (2) ; Pressure value of compression spring (18) The calculation formula is: S3. Set the workpiece clamping force parameters: Set the target clamping force according to the material and size of the workpiece. and the allowable fluctuation threshold of the tightening force ; S4. Clamping the workpiece: Move the machine tool tailstock to a suitable position relative to the workpiece, and start the automatic clamping force detection and adjustment program in the control system. The control system will adjust the clamping force according to the target clamping force. The control drive component drives the center sleeve (2) forward, which in turn drives the rotating center (3) to feed and clamp the workpiece; During this process, the control system uses a preset clamping force sampling period. The measurement values ​​of the first laser rangefinder (10) are continuously collected. The measured values ​​of the second laser ranging sensor (11) And based on the measurement value of the first laser rangefinder (10) The measured values ​​of the second laser ranging sensor (11) Calculate the actual clamping force ,when At this time, the drive component stops moving, and the actual clamping force... The calculation formula is: S5. Automatic detection and adjustment of clamping force during workpiece processing: During the workpiece processing, the workpiece expands due to heat, and the compression spring (18) is further compressed, resulting in an actual clamping force. The force gradually increases, and the control system samples the force at a preset interval. The measurement values ​​of the first laser rangefinder (10) are continuously collected. The measured values ​​of the second laser ranging sensor (11) And based on the measurement value of the first laser rangefinder (10) The measured values ​​of the second laser ranging sensor (11) Calculate the actual clamping force ,when At that time, the control system automatically outputs an adjustment signal to control the drive component to drive the rotary tip (3) backward until... Stop at this time; S6. Processing completed: After processing is completed, the control system controls the drive assembly to drive the rotary center (3) back to the set origin position and remove the processed workpiece.

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