Ball screw pair axial play measuring device

Abstract

This application provides an axial clearance measuring device for ball screw pairs. It uses a top-down nut clamping structure and a screw clamping structure to vertically position the nut and screw of the ball screw pair to be tested. Compared to existing measuring structures that use a clamping structure where the screw and nut are placed laterally, this avoids the problem of inaccurate measurement results caused by center offset due to the lateral placement of a long screw. This application uses a U-shaped fixed clamping block and a U-shaped rotating clamping block in the screw clamping structure, forming an interlocking plug-in structure. A shrinkage slit is provided on the first clamping arc to ensure that the screw clamping structure can effectively clamp any part of the long screw. This avoids the problem of dimensional errors in the long screw during processing affecting the clamping effect and thus the measurement results.

Description

Technical Field

[0001] This invention relates to the field of ball screw pair measurement technology, specifically to a ball screw pair axial clearance measuring device. Background Technology

[0002] A ball screw assembly, consisting of a screw and a ball nut, is a widely used transmission mechanism. During operation, the ball screw and nut utilize a helical transmission with steel balls as rolling elements, converting the rotational motion of the nut into linear motion. The axial clearance between the screw and the ball nut is a crucial quality parameter of the ball screw assembly. Existing technologies include testing devices for ball screw assemblies, such as patent CN105973124A, which discloses a device for detecting the axial clearance of a ball screw assembly. In this device, the nut 10 is fixed within a nut holder 200, and the screw 20 is assembled with the nut 10, placed horizontally. The output shafts 310b of the first and second push-pull pressure gauges 300a and 300b apply axial pressure to both ends of the screw 20 to complete the measurement. However, this method of measuring by directly applying pressure to both ends of the horizontally placed screw is not suitable for ball screw assemblies with long screws. For example, in the ball screw assembly used in automotive steering structures, if a transversely placed measurement method is adopted, the offset of the center of gravity of the transversely placed ball screw will affect the measurement results when the nut and the screw move relative to each other, thus leading to inaccurate measurement results. Summary of the Invention

[0003] To address the problem that existing ball screw pair measuring devices are unsuitable for measuring the axial clearance of long ball screw pairs, this invention provides a ball screw pair axial clearance measuring device that can provide accurate measurement of the axial clearance of ball screw pairs, and is particularly suitable for measuring the axial clearance of long ball screw pairs.

[0004] The technical solution of the present invention is as follows: an axial clearance measuring device for a ball screw pair, comprising: a loading structure and a measuring structure; characterized in that it further comprises: a positioning structure, a universal floating structure, and a pre-positioning structure; all structures are mounted on a main support;

[0005] The positioning structure includes: a nut clamping structure and a screw clamping structure; the nut clamping structure is installed above the screw clamping structure, and the screw clamping structure is installed on the universal floating structure; the pre-positioning structure is installed below the nut clamping structure.

[0006] After the ball screw assembly to be tested is fed, the nut of the ball screw assembly is placed on the nut seat in the nut clamping structure, and the screw is initially positioned by the pre-positioning structure. After the screw clamping structure in the positioning structure clamps the screw, the pre-positioning structure releases the screw. Then, the nut clamping structure presses the nut into the nut seat from top to bottom. At the same time, the screw clamping structure adjusts the center of gravity of the screw based on the universal floating structure, so that the center of gravity of the nut and the screw are on the same vertical line, thus completing the positioning of the nut and the screw.

[0007] The loading structure applies a measuring force to the ball screw pair to be tested, and the measuring structure measures the axial clearance of the ball screw pair to be tested.

[0008] The nut clamping structure includes: a nut seat, a nut seat base plate, and a four-position lever clamping structure;

[0009] The size and shape of the nut seat are adapted to the nut of the ball screw pair to be tested, and an anti-rotation structure is provided in the inner cavity of the nut seat; the nut seat is horizontally mounted on the main support through the nut seat base plate, and four lever clamping structures are arranged on the outer periphery of the nut seat; the clamping end of the lever clamping structure is located above the nut seat;

[0010] The lead screw clamping structure includes: a floating plate, a fixed clamping block, a rotating clamping block, a clamping cylinder, and a clamping rotating shaft;

[0011] The floating plate is horizontally mounted on the omnidirectional floating structure;

[0012] The fixed clamping block is fixedly mounted on the floating plate, and the clamping rotation shaft is vertically mounted on the floating plate; the output shaft of the clamping cylinder is horizontally arranged.

[0013] The rotating clamping block is movably mounted on the floating plate, with one end rotatably mounted on the clamping rotating shaft and the other end connected to the output shaft of the clamping cylinder;

[0014] A semi-circular first clamping arc opening is provided on the rotating clamping block at the position between the clamping cylinder and the clamping rotating shaft, on the side away from the output shaft of the clamping cylinder; a semi-circular second clamping arc opening is provided on the fixed clamping block, and the first clamping arc opening and the second clamping arc opening constitute a circular clamping opening;

[0015] The second clamping arc of the fixed clamping block is set as a horizontal U-shaped structure, with the open end facing the rotating clamping block. The second clamping arc is also set on the upper and lower horizontal plates of the U-shape.

[0016] The rotating clamping block is configured as a U-shaped structure, with the middle horizontal plate of the U-shape protruding and its thickness adapted to the distance between the upper and lower horizontal plates of the fixed clamping block; the U-shaped structure of the fixed clamping block and the U-shaped structure of the rotating clamping block form an interlocking plug-in structure.

[0017] Its further features are:

[0018] A shrinkage slit is provided on the first clamping arc opening, and the shrinkage slit is evenly distributed on the first clamping arc opening along the radial direction; when elastic deformation occurs, the annular structure maintains elastic margin through the setting of the conical sleeve shrinkage slit; one end of the shrinkage slit is open, and the shrinkage slit penetrates the rotating clamping block in the thickness direction, and its length is less than the width of the annular structure in which it is located;

[0019] The measurement structure includes: a measuring pen structure and a compensation structure;

[0020] The measuring pen structure includes: a clearance measuring pen, a positioning ball, an adjusting rod, a clearance measuring motor, a clearance measuring slide rail, a measuring bracket, a positioning frame, a measuring slide plate, and a clearance measuring lead screw;

[0021] The clearance measuring motor and the clearance measuring slide rail are mounted on the main support, and the measuring slide plate is slidably mounted on the clearance measuring slide rail. The clearance measuring motor drives the measuring slide plate to slide along the clearance measuring slide rail.

[0022] The measuring bracket is mounted on the measuring slide plate; the positioning portal frame is mounted below the measuring bracket with its opening facing downwards, and the measuring end of the clearance measuring pen is mounted below the crossbeam of the positioning portal frame with its measuring end facing downwards;

[0023] The two ends of the adjusting rod are movably mounted on the two side walls of the positioning frame, and the positioning ball is movably fitted onto the adjusting rod; the size of the positioning ball is adapted to the size of the center hole at the top of the ball screw in the ball screw pair to be measured; there is space for vertical movement between the adjusting rod and the positioning frame, and between the adjusting rod and the positioning ball;

[0024] The measuring end of the clearance measuring pen, the center of the positioning ball, and the center of the nut are located on the same vertical line;

[0025] The compensation structure includes: a compensation measuring cylinder, a compensation measuring pen, a compensation portal frame, a compensation slide rail, a compensation sliding frame, a nut end face clamping seat, and a compensation test reference nut;

[0026] The compensation slide rail is vertically mounted on the main support, and the compensation portal frame is mounted on the base plate of the nut seat; the compensation sliding frame is slidably connected to the compensation slide rail; the compensation measuring cylinder is mounted on the top crossbeam of the compensation portal frame and drives the compensation sliding frame to slide along the compensation slide rail.

[0027] The reference nut used for compensation testing is vertically installed inside the compensation portal frame;

[0028] A compensation measuring pen is installed below the compensation sliding frame, and the compensation measuring pen and the reference nut are located on the same vertical line;

[0029] The end face clamping seat of the nut is installed below the compensation sliding frame. The cylindrical end face clamping seat of the nut is concentrically arranged with the nut seat and located above the nut seat.

[0030] The loading structure includes: a loading motor, a loading slide rail, a loading lead screw, a loading nut, an S-type spring force sensor, a loading connection structure, and two sets of force transmission springs.

[0031] The loading connection structure includes: a clamping structure outer plate, an upper spring plate and a lower spring plate disposed at both ends of the S-shaped spring force sensor, and a first fixing plate, a spring connecting plate, and a second fixing plate disposed from top to bottom;

[0032] The loading screw and the loading slide rail are mounted parallel and vertically on the main support, the loading nut is mounted on the loading screw, and the output shaft of the loading motor is connected to the loading screw;

[0033] The spring connecting plate is fixedly connected to the loading nut, the upper spring plate is connected to the spring connecting plate, and the upper and lower ends of the S-shaped spring force sensor abut against the upper spring plate and the lower spring plate, respectively.

[0034] Two sets of force transmission springs are respectively provided on the upper and lower end faces of the lower top plate of the spring; the top end of the upper force transmission spring abuts against the first fixed plate and the bottom end abuts against the lower top plate of the spring; the two ends of the lower force transmission spring abut against the lower top plate of the spring and the second fixed plate, respectively.

[0035] The first fixing plate, the second fixing plate, and the spring connecting plate are respectively slidably connected to the loading slide rail based on the slider;

[0036] One side of the clamping structure's outer plate is connected to both the first and second fixing plates, while the other side is provided with the universal floating structure and the lead screw clamping structure.

[0037] The omnidirectional floating structure includes: a planar moving structure and a ball joint structure;

[0038] The planar moving structure includes: a planar slider, four sets of linear guides, and two sets of guide rail base plates; of the four sets of linear guides, two sets are x-axis guides, arranged in parallel on one guide rail base plate, and the other two sets are y-axis guides, arranged in parallel on another guide rail base plate; the two guide rail base plates are arranged vertically, with the upper guide rail base plate slidably mounted on the linear guides of the lower guide rail base plate based on the slider structure at the bottom; the planar slider is slidably mounted on the linear guides of the upper guide rail base plate; the lower guide rail base plate is mounted on the loading structure;

[0039] The ball joint structure includes: a ball joint seat and a ball joint; the ball joint seat includes: a base body and a top connecting plate; the center of the ball joint is provided with a vertical central hole, the diameter of which is adapted to the diameter of the lead screw;

[0040] The base body has a spherical cavity adapted to the size of the ball joint; the ball joint is movably installed in the spherical cavity with the central hole perpendicular to it; the base body is fixedly installed on the planar slider; the top connecting plate is provided on the upper end face of the base body;

[0041] The top connecting plate and the planar slider have lead screw through holes at positions corresponding to the spherical inner cavity, which are adapted to the central hole of the ball joint; the floating plate of the lead screw clamping structure is horizontally mounted on the top connecting plate;

[0042] The pre-positioning structure includes: a lead screw middle positioning structure and a lead screw bottom positioning structure;

[0043] The bottom positioning structure of the lead screw includes: a bottom positioning cylinder and a bottom pre-positioning shaft; the middle positioning structure of the lead screw includes: a middle pre-positioning gripper;

[0044] The pre-positioning structure also includes: an auxiliary support structure, including an auxiliary support rod, a cylinder for the support rod, and a support cap; the support caps are arranged in pairs, with the support cap and the auxiliary support rod arranged in a one-to-one ratio; the cylinder for the support rod is set on the clamping mounting plate, the support cap is set on the floating plate, and a positioning cavity is opened at the bottom; the auxiliary support rod is set vertically, with the bottom connected to the output end of the cylinder for the support rod, and a positioning tip is set at the top, the positioning tip being adapted to the positioning cavity;

[0045] It also includes: counterweight structure;

[0046] The counterweight structure includes: a counterweight block, a counterweight slide rail, a chain, and a counterweight sprocket;

[0047] The counterweight slide rail is vertically mounted on the main support, and two sets of counterweight sprockets are mounted at the same height, one set being mounted above the screw clamping structure and the other set being mounted above the counterweight block.

[0048] The chain is laid on two sets of counterweight sprockets at the same time. One end of the chain is connected to the counterweight block, and the other end is connected to the clamping structure outer plate of the loading structure.

[0049] The nut clamping structure further includes: a nut lifting structure;

[0050] The nut lifting structure includes: a horizontally arranged propulsion cylinder and a nut clamping part connected to the output end of the propulsion cylinder;

[0051] The nut clamping part has a U-shaped structure. The closed end of the U-shaped opening is connected to the propulsion cylinder. The top horizontal bar at the U-shaped opening is the limiting end, and the bottom horizontal bar is the lifting end. The distance between the limiting end and the lifting end is adapted to the height of the bottom engagement protrusion of the nut.

[0052] The nut seat has a sliding groove at each end of a diameter, and the openings of the nut clamping parts of the two nut lifting structures are arranged in the sliding grooves with the nut facing the nut direction; the height of the lifting end is greater than the depth of the sliding groove.

[0053] The lifting end, away from the propulsion cylinder, is provided with an insertion guide slope. The head of the guide slope is narrower, while the side adjacent to the propulsion cylinder is wider.

[0054] This application provides an axial clearance measuring device for ball screw pairs. It uses a top-down nut clamping structure and a screw clamping structure to vertically position the nut and screw of the ball screw pair to be tested. Compared with existing measuring structures that place the screw and nut laterally, this avoids the problem of inaccurate measurement results caused by center offset due to the lateral placement of the long screw. This application uses a U-shaped fixed clamping block and a U-shaped rotating clamping block in the screw clamping structure, forming an interlocking insertion structure. A shrinkage slit is provided on the first clamping arc to ensure that the screw clamping structure can effectively clamp any part of the long screw. This avoids the problem of dimensional errors in the long screw during processing affecting the clamping effect and thus the measurement results. Furthermore, this application sets the screw clamping structure on a universal floating structure, adjusting the center of gravity of the screw and nut to be on the same vertical line, avoiding the impact of the long screw's center of gravity offset on the accuracy of the measurement results, and improving the accuracy of the measurement. The accuracy of the measurement results is improved. This application applies a test force through a loading structure and completes the axial clearance measurement based on the measurement structure. Because the axial clearance measuring device used in long screw ball screw pairs has a relatively long length, the measuring device will also deform when the ball screw pair is under force, resulting in errors in the detected value of the ball screw pair. In this application, a compensation structure is set in the test structure to measure the deformation of the measuring device. The measurement structure in this application includes a measuring pen structure and a compensation structure. In the compensation structure, the reference nut is installed on the main support, and the compensation measuring pen and the screw nut end face clamping seat are installed on the compensation sliding frame. During measurement, the screw nut end face clamping seat is pressed against the top face of the screw nut, and the compensation measuring pen contacts the upper end face of the reference nut. The deformation of the system itself during the measurement process is detected by the displacement change between the reference nut and the compensation measuring pen. The deformation of the system itself is subtracted from the clearance value of the ball screw pair detected by the clearance measuring pen to ensure that the obtained axial clearance detection value is more accurate. This application is particularly suitable for measuring the axial clearance of long screw ball screw pairs. Attached Figure Description

[0055] Figure 1 This is a schematic diagram of the main view of the ball screw pair axial clearance measuring device.

[0056] Figure 2 This is a schematic diagram of the left view of the axial clearance measuring device for a ball screw pair.

[0057] Figure 3 This is a rear view structural schematic diagram of the ball screw pair axial clearance measuring device;

[0058] Figure 4 A schematic diagram of the main view of the measuring structure and the nut clamping structure;

[0059] Figure 5 This is a right-view structural diagram of the measuring pen structure;

[0060] Figure 6 This is a schematic diagram illustrating the effect of the female connector.

[0061] Figure 7 A cross-sectional structural diagram of the positioning sphere;

[0062] Figure 8 A schematic diagram of the structure for lifting the nut;

[0063] Figure 9 This is a schematic diagram of the main view structure of the loading structure;

[0064] Figure 10 A schematic diagram of the structure from the left view of the loading structure.

[0065] Figure 11 A three-dimensional schematic diagram of the clamping and loading structures;

[0066] Figure 12 This is a schematic diagram of the clamping structure from the front view.

[0067] Figure 13 This is a top view of the clamping structure.

[0068] Figure 14 This is a schematic diagram of the clamping structure from the left view.

[0069] Figure 15 A perspective rendering of an omnidirectional floating structure;

[0070] Figure 16 A schematic diagram showing the cross-sectional effect of the nut lifting structure and nut seat. Detailed Implementation

[0071] like Figures 1-3 As shown, this application includes a ball screw pair axial clearance measuring device, which includes: a measuring structure, a positioning structure, a loading structure 9, a universal floating structure 8, a pre-positioning structure and a counterweight structure 11, all of which are mounted on the main support 1.

[0072] The positioning structure includes a lead screw clamping structure 6 and a lead screw clamping structure 7. The measuring structure includes a measuring pen structure 4 and a compensation structure 5; the pre-positioning structure includes a lead screw middle positioning structure and a lead screw bottom positioning structure 10. The lead screw clamping structure 6 is installed above the lead screw clamping structure 7, and the lead screw clamping structure 7 is installed on the universal floating structure 8.

[0073] The bottom positioning structure 10 of the lead screw includes a bottom positioning cylinder 1002, a bottom pre-positioning shaft 1001, and a bottom slide rail 1003; the middle positioning structure of the lead screw includes a middle pre-positioning gripper 12. Both lead screw pre-positioning structures are installed below the lead screw nut clamping structure 6. The middle pre-positioning gripper is located in the middle position below the lead screw nut clamping structure 6. The bottom positioning structure 10 of the lead screw is installed on the main support 1, located below the loading structure 9. A positioning ball (not marked in the figure) adapted to the size of the bottom positioning center hole of the lead screw is provided on the bottom pre-positioning shaft 1001 to ensure that the lead screw 3 can be vertically supported to complete the initial positioning of the lead screw 3, while preventing the lead screw nut 2 and the lead screw 3 from separating. The output end of the bottom positioning cylinder 1002 is connected to the bottom pre-positioning shaft 1001, driving the bottom pre-positioning shaft 1001 to slide up and down along the bottom slide rail 1003.

[0074] After the ball screw assembly to be tested is fed, the nut 2 of the ball screw assembly is placed on the nut seat 601 in the nut clamping structure 6. The screw 3 passes through the nut seat 601, the middle pre-positioning claw 12, the screw clamping structure 7, and the universal floating structure 8 from top to bottom. The bottom end of the screw 3 rests on the bottom pre-positioning shaft 1001. The bottom pre-positioning shaft 1001 and the nut seat 601 jointly support the screw 3, and after the initial positioning of the screw 3 is achieved, the middle pre-positioning claw 12 is activated to clamp the middle of the screw 3. After the middle pre-positioning claw 12 clamps, the bottom positioning cylinder 1002 drives the bottom pre-positioning shaft 1001 downward to disengage from the bottom of the screw 3.

[0075] Then, after the lead screw 3 is clamped by the lead screw clamping structure 7 in the positioning structure, the middle pre-positioning jaw 12 releases the middle of the lead screw 3; then the lead screw nut pressing structure 6 is driven to press the lead screw nut 2 from top to bottom in the lead screw nut seat 601. While the lead screw nut 2 is being pressed, the lead screw clamping structure 7 adjusts the center of gravity of the lead screw based on the universal floating structure 8, so that the center of gravity of the lead screw nut 2 and the lead screw 3 are on the same vertical line, thus completing the positioning of the lead screw nut 2 and the lead screw 3.

[0076] Finally, a measuring force is applied to the lead screw 3 in the ball screw pair under test through the loading structure 9, and the axial clearance of the ball screw pair under test is measured through the measuring structure. During the measurement process, the compensation probe 502 in the compensation structure 5 simultaneously measures the deformation of the entire measuring system under the measuring force. Finally, the system deformation is subtracted from the measurement value of the clearance probe 401 to obtain the measured value.

[0077] like Figures 4-7 As shown, the nut clamping structure 6 includes: nut seat 601, nut seat base plate 602, and four-position lever clamping structure 603.

[0078] like Figure 6As shown, the size and shape of the nut seat 601 are adapted to the nut 2 of the ball screw pair to be tested. The nut seat 601 is provided with an anti-rotation structure in its inner cavity. Specifically, the anti-rotation structure engages with the bottom end face of the nut to prevent the nut from rotating in the nut seat. The nut seat 601 is horizontally mounted on the main support 1 via the nut seat base plate 602. Four lever clamping structures 603 are provided on the outer periphery of the nut seat 601. The clamping ends of the lever clamping structures 603 are located above the nut seat 601.

[0079] The lever clamping structure 603 includes a nut clamping cylinder 6031, a lever support rod 6034, and an L-shaped tension rod 6032. The lever support rod 6034 is vertically mounted on the nut seat base plate 602. The clamping cylinder 6031 is mounted on the nut seat base plate 602, and its output end is vertically connected to the vertical rod of the L-shaped tension rod 6032. The horizontal rod of the L-shaped tension rod 6032 is hinged to the lever support rod 6034 via a fulcrum pin 6033. A clamping block is provided at the end of the horizontal rod of the L-shaped tension rod 6032 facing the nut seat 601. When it is necessary to clamp the nut in the nut seat 601, the nut clamping cylinder 6031 pushes the vertical rod of the tension rod 6032 upward, and the tension rod 6032 rotates around the fulcrum pin, while the clamping block presses down on the upper end face of the nut 2.

[0080] The lever clamping structure 603 is evenly arranged on the outer circumference of the nut seat 601 to ensure that uniform pressure can be applied to the nut in the nut seat 601, and to ensure that the nut will not deflect during the measurement process, thereby ensuring the accuracy of the measurement results.

[0081] The measuring structure includes: a measuring pen structure 4 and a compensation structure 5. The measuring pen structure 4 includes: a clearance measuring pen 401, a positioning ball 402, an adjusting rod 403, a clearance measuring motor 404, a clearance measuring slide rail 405, a measuring bracket 406, a positioning portal frame 407, a measuring slide plate 408, a clearance measuring lead screw 409, and a clearance nut 410.

[0082] The clearance measuring motor 404 and the clearance measuring slide rail 405 are mounted on the main support 1. The measuring slide plate 408 is slidably mounted on the clearance measuring slide rail 405 and is mounted on the clearance nut 410. The clearance measuring motor 404 drives the clearance nut 410 to move up and down through the clearance measuring screw 409, thereby driving the measuring slide plate 408 to slide along the clearance measuring slide rail 405.

[0083] The measuring bracket 406 is mounted on the measuring slide plate 408. The positioning portal frame 407 is mounted below the measuring bracket 406 with its opening facing downwards. The measuring end of the clearance measuring pen 401 is mounted below the crossbeam of the positioning portal frame 407 with its measuring end facing downwards. The two ends of the adjusting rod 403 are movably mounted on the two side walls of the positioning portal frame 407. The positioning ball 402 is movably fitted onto the adjusting rod 403. The size of the positioning ball 402 is adapted to the size of the center hole at the top of the ball screw in the ball screw pair to be measured. There is vertical space between the adjusting rod 403 and the positioning portal frame 407, and between the adjusting rod 403 and the positioning ball 402.

[0084] The measuring end of the clearance measuring pen 401, the center of the positioning ball 402, and the center of the lead screw nut 601 are located on the same vertical line, ensuring that the measuring end of the clearance measuring pen 401, the center of gravity of the lead screw nut, and the center of gravity of the lead screw are on the same vertical line during the measurement process, thereby ensuring that the clearance between the lead screw nut and the lead screw can be accurately measured.

[0085] The compensation structure 5 includes: a compensation measuring cylinder 501, a compensation measuring pen 502, a compensation portal frame 503, a compensation slide rail 504, a compensation sliding frame 505, a nut end face clamping seat 506, and a compensation test reference nut 507; the compensation slide rail 504 is vertically mounted on the main support 1, and the compensation portal frame 503 is mounted on the nut base plate 602; the compensation sliding frame 505 is slidably connected to the compensation slide rail 504; the compensation measuring cylinder 501 is mounted on the top crossbeam of the compensation portal frame 503, driving... The sliding frame 505 for dynamic compensation slides along the sliding rail 504 for compensation; the reference nut 507 for compensation testing is vertically installed inside the frame 503 for compensation based on the nut mounting plate 508; a compensation test pen 502 is set below the sliding frame 505 for compensation, and the compensation test pen 502 and the reference nut 507 are located on the same vertical line; the end face clamping seat 506 of the nut is installed below the sliding frame 505 for compensation, and the cylindrical end face clamping seat 506 of the nut is concentrically set with the nut seat 601 and located above the nut seat 601.

[0086] The reference nut 507 is mounted on the main support 1 via the compensation bracket 503 and the nut base plate 602. The compensation probe 502 and the nut end face clamping seat 506 are simultaneously mounted on the compensation sliding frame 505. During measurement, the nut end face clamping seat 506 is pressed against the top surface of the nut, and the compensation probe 502 contacts the upper end face of the reference nut 507, which is the 0 value position.

[0087] The compensation measuring pen 502 is mounted on the main support 1 via the compensation sliding frame 505 and the compensation slide rail 504. The reference nut 507 is mounted on the nut base plate 602 via the compensation portal frame 503. The nut is set on the nut base plate 602 via the nut seat 601. The test force applied to the lead screw by the loading structure 9 is transmitted to the nut base plate 602 after the nut is subjected to force. If the nut seat 601, the nut base plate 602 and other structures deform after being subjected to force, the deformation will be reflected in the reference nut 507. When the position of the reference nut 507 changes, the measurement value of the compensation measuring pen 502 will change. The deformation value of the system itself under force during the measurement process can be detected by the displacement change between the reference nut 507 and the compensation measuring pen 502.

[0088] Initially, the clearance measuring pen 401 contacts the positioning ball 402, and the initial value of the pen is zeroed. After the measurement begins, the clearance measuring motor 404 drives the measuring slide plate 408 to slide vertically along the clearance measuring slide rail 405, causing the adjusting rod 403 and the positioning ball 402, which is movably mounted on the adjusting rod 403, to move to the center hole at the top of the ball screw in the ball screw pair to be measured. The bottom position of the positioning ball 402 is fixed. The clearance measuring motor 404 continues to drive the adjusting rod 403 downward, causing the adjusting rod 403 and the positioning ball 402 to disengage. As the adjusting rod 403 continues to descend, the measured value of the clearance measuring pen 401 changes. When the measured value detected by the pen changes to the preset value, indicating that the pen has reached the measurement position, the clearance measuring motor 404 stops. The ball screw assembly in this application is a precision device whose axial clearance is measured in micrometers, so a high-precision sensor is required. In this embodiment, the clearance measuring pen 401 and the compensation measuring pen 502 are based on a displacement sensor, such as an optical magnetic high-precision displacement sensor. The specific installation and detection methods of the displacement sensor can be implemented based on any displacement sensor in the existing technology.

[0089] After the gap measuring motor stops, the compensation measuring cylinder 501 starts, driving the nut end face clamping seat 506 and the compensation measuring pen 502 to slide down along the compensation slide rail 504 until the nut end face clamping seat 506 presses against the upper end face of the nut; at this time, the compensation measuring pen 502 also contacts the upper end face of the reference nut 507 and reaches the 0 value position.

[0090] The reference nut 507 is vertically installed inside the compensation portal frame 503 via the nut mounting plate 508. The reference nut 507 is threadedly connected to the nut mounting plate 508. The height of the reference nut 507 can be adjusted according to specific measurement requirements, and it is suitable for ball screw pairs of different sizes.

[0091] The required loading force for measuring ball screw pairs varies depending on the product model. Different loading forces will cause deformation of the entire measuring device system, resulting in changes in the overall rigidity of the system. This application measures the system deformation value using the compensation structure 5, and then subtracts the system deformation value from the measurement result of the clearance measuring pen 401 to ensure more accurate measurement results.

[0092] During each measurement, the screw in the ball screw pair is lifted once by the loading structure 9 and then pulled down once. The two forces will cause the clearance measuring pen 401 to produce two measurement values. The difference between the two measurement values ​​is the clearance detection value for this measurement. Similarly, the difference between the two measurement values ​​detected by the compensation measuring pen 502 during the two force application processes is the deformation value of the system for this measurement.

[0093] Because the lead screw in the ball screw assembly being measured in this application is a long lead screw, the axial clearance needs to be tested at different positions on the long lead screw during implementation, and the average of multiple measurements is then taken. Therefore, after each measurement, the next preset measurement position needs to be adjusted. In practice, after the previous measurement is completed, the lead screw nut 2 needs to be lifted before adjusting the position of the lead screw 3. Because it is necessary to prevent the lead screw nut from rotating when measuring the axial clearance, an anti-rotation structure is provided in the lead screw nut seat 601 of this application. However, when adjusting the lead screw position, the lead screw nut needs to rotate, so this application also provides a lead screw nut lifting structure 609 in the lead screw nut clamping structure 6.

[0094] like Figure 7 and Figure 8 As shown, the nut lifting structure 609 includes: a horizontally arranged propulsion cylinder 6091 and a nut clamping part 6092 connected to the output end of the propulsion cylinder;

[0095] The nut clamping part has a U-shaped structure. The closed end of the U-shaped opening is connected to the propulsion cylinder. The top crossbar at the U-shaped opening is the limiting end 6093, and the bottom crossbar is the lifting end 6094. The distance between the limiting end 6093 and the lifting end 6094 is adapted to the height of the bottom engaging protrusion 201 of the nut, as detailed below. Figure 16 As shown;

[0096] A sliding groove 6010 is provided at both ends of a diameter on the nut seat 601. The openings of the nut clamping parts of the two nut lifting structures 609 are arranged in the sliding grooves with the nut direction facing the nut. The height of the lifting end 6094 is higher than the depth of the sliding groove.

[0097] An insertion guide slope 6095 is provided at the end of the raised end 6094 that is away from the propulsion cylinder. The head of the guide slope 6095 is narrower, and the side adjacent to the propulsion cylinder is wider.

[0098] Initially, the nut clamping part is in the groove, located at the position of the original nut, which does not obstruct the measurement process. When it is necessary to lift the nut, the push cylinder is activated, pushing the nut lifting end 6094 along the groove into the inner cavity of the nut seat 601. The head of the guide slope 6095 is narrow and will directly insert into the bottom of the nut. The push cylinder continues to push, and the bottom engagement protrusion of the nut fully enters the nut clamping part. Because the height of the lifting end 6094 is higher than the depth of the groove, the bottom of the nut leaves the bottom of the nut seat 601 and is not obstructed by the anti-rotation structure at the bottom of the nut seat 601. At this time, the loading motor in the loading structure 9 is activated, and the screw is pulled up or down through the screw clamping structure 7. The nut rotates on the end face of the nut lifting end 6094, adjusting the test position of the screw. The limiting end 6093 of the screw nut clamping part is to prevent the screw nut from shifting in the height direction. The setting of the limiting end 6093 ensures that the screw nut will not detach from the screw nut clamping part, but will rotate in place and change the test position of the screw and screw nut contact.

[0099] like Figure 9 , Figure 10 and Figure 11 As shown, the loading structure 9 includes: a loading motor 901, a loading slide rail 902, a loading lead screw 903, a loading nut 904, an S-shaped spring force sensor 905, a loading connection structure, and four force transmission springs 906 in two sets (upper and lower). The loading connection structure includes: an outer clamping plate 907, an upper spring plate 908 and a lower spring plate 909 located at both ends of the S-shaped spring force sensor 905, and a first fixing plate 910, a spring connecting plate 911, and a second fixing plate 912 arranged from top to bottom.

[0100] The loading screw 903 and the loading slide rail 902 are mounted parallel and vertically on the main support 1. The loading nut 904 is mounted on the loading screw 903. The output shaft of the loading motor 901 is connected to the loading screw 903.

[0101] The spring connecting plate 911 is located between the first fixed plate 910 and the second fixed plate 912; the spring connecting plate 911 is fixedly connected to the loading nut 904, the upper spring plate 908 is connected to the spring connecting plate 911, and the upper and lower ends of the S-shaped spring force sensor 905 abut against the upper spring plate 908 and the lower spring plate 909 respectively.

[0102] Two sets of four force-transmitting springs 906 are respectively installed on the upper and lower end faces of the lower spring top plate 909; the top ends of the two upper force-transmitting springs abut against the first fixing plate 910, and the bottom ends abut against the lower spring top plate 909; the two ends of the lower force-transmitting springs 906 abut against the lower spring top plate 909 and the second fixing plate 912, respectively. Specifically, a first horizontal plate 913 is installed on the first fixing plate 910, and a second horizontal plate 914 is installed on the second fixing plate 912; two sets of force-transmitting springs 906 are respectively installed on the upper and lower end faces of the lower spring top plate 909; the two ends of the lower force-transmitting springs 906 abut against the lower spring top plate 909 and the second horizontal plate 914, respectively; the top ends of the upper force-transmitting springs abut against the first horizontal plate 913, and the bottom ends abut against the lower spring top plate 909.

[0103] The first fixed plate 910, the second fixed plate 912, and the spring connecting plate 911 are slidably connected to the loading slide rail 902 based on the slider.

[0104] One side of the clamping structure outer plate 907 is connected to both the first fixed plate 910 and the second fixed plate 912, while the other side is equipped with a universal floating structure 8 and a lead screw clamping structure 7. The clamping structure outer plate 907 is U-shaped, with two protruding structures at the open end connecting to the first fixed plate 910 and the second fixed plate 912 respectively. The clamping structure outer plate 907 is not directly connected to the middle spring connecting plate 911 to ensure accurate force transmission.

[0105] The S-type spring force sensor 905 abuts against the upper spring plate 908 and the lower spring plate 909 at its upper and lower ends, respectively. The top of the S-type spring force sensor 905 is connected to the spring connecting plate 911 through the upper spring plate 908, and the bottom of the S-type spring force sensor 905 is connected to the first fixing plate 910 and the second fixing plate 912 through the lower spring plate 909 and two sets of force transmission springs 906, and then connected to the clamping structure outer plate 907. When the loading motor 901 drives the loading nut 904 to move along the loading slide rail 902, the loading nut 904 drives the spring connecting plate 911 to move. Through the upper spring plate 908, the S-type spring force sensor 905, the lower spring plate 909, the first fixing plate 910, the second fixing plate 912, and the clamping structure outer plate 907, the force is transmitted to the lead screw clamping structure 7, that is, the test force is applied vertically to the lead screw 3 in the ball screw pair to be tested. In this application, the S-type spring force sensor 905 can simultaneously detect and transmit forces in multiple directions, ensuring the accuracy of the detection results. This application uses four force transmission springs 906, divided into upper and lower groups, respectively positioned in the upper and lower directions of the S-type spring force sensor 905 to transmit force, ensuring that the test force applied by the loading motor can be smoothly transmitted to the clamping structure. This is particularly suitable for force transmission in the testing of ball screw pairs with long lead screws.

[0106] When the loading structure 9 needs to apply force to the lead screw, the loading motor starts. Assuming the loading lead screw 903 rotates, it drives the loading nut 904 to move upward in the vertical direction. The spring connecting plate 911 installed on the loading nut 904 moves with the loading nut 904. The spring connecting plate 911 drives the upper spring plate 908 to pull the S-type spring force sensor 905 upward. The S-type spring force sensor 905 drives the lower spring plate 909 to move upward. The lower spring plate 909 pushes up the two sets of force transmission springs 906 above. The upper force transmission springs 906 push up the first fixed plate 910. The first fixed plate 910 and the second fixed plate 912 are fixedly connected by the clamping structure outer plate 907. When the two slide upward along the loading slide rail 902, the clamping structure outer plate 907 drives the universal floating structure 8 and the clamping structure to move upward, that is, to apply an upward force to the lead screw.

[0107] When the loading motor drives the loading screw nut 904 to move downwards in the vertical direction, the spring connecting plate 911 drives the upper spring plate 908 to press down on the S-type spring force sensor 905. The S-type spring force sensor 905 drives the lower spring plate 909 to move downwards. The lower spring plate 909 applies force downwards to the two sets of force transmission springs 906 below. The two sets of force transmission springs 906 apply force downwards to press down on the second fixing plate 912. The second fixing plate 912, the first fixing plate 910, and the clamping structure outer plate 907 slide downwards along the loading slide rail 902. Then, the loading structure 9 applies a downward force to the screw.

[0108] like Figure 12 , Figure 13 and Figure 14 As shown, the omnidirectional floating structure 8 includes: a planar moving structure 81 and a ball joint structure 82.

[0109] The planar moving structure 81 includes: a planar slider 8101, four sets of linear guide rails 8102, and two sets of guide rail base plates 8103. Of the four sets of linear guide rails 8102, two sets are x-axis guide rails, arranged in parallel on one guide rail base plate 8103, and the other two sets are y-axis guide rails, arranged in parallel on the other guide rail base plate 8103. The two guide rail base plates 8103 are arranged vertically, with the upper guide rail base plate 8103 slidably mounted on the linear guide rails 8102 of the lower guide rail base plate 8103 based on the slider structure at its bottom. The planar slider 8101 is slidably mounted on the linear guide rails 8102 on the upper guide rail base plate 8103. The lower guide rail base plate 8103 is mounted on the clamping structure external plate 907 of the loading structure 9 via a clamping mounting plate 8104. This application uses the planar moving structure 81 to achieve arbitrary movement of the lead screw clamping structure 7 in the x and y directions.

[0110] like Figure 15As shown, the ball joint structure 82 includes a ball joint 8201 and a ball joint seat. A vertical central hole is provided at the center of the ball joint 8201, the diameter of which is adapted to the diameter of the lead screw. The ball joint seat includes a base body 8202 and a top connecting plate 8203. A spherical cavity adapted to the size of the ball joint 8201 is formed in the inner cavity of the base body 8202; the ball joint 8201 is movably installed in the spherical cavity with the central hole perpendicular to it; the base body 8202 is fixedly mounted on the planar slider 8101; the top connecting plate 8203 is provided on the upper end face of the base body 8202; lead screw through holes adapted to the central hole of the ball joint 8201 are formed at positions on the top connecting plate 8203 and the planar slider 8101 corresponding to the spherical cavity. The ball joint 8201 slides freely within the spherical cavity of the ball joint seat, ensuring that the lead screw 3 can swing at any angle based on the ball joint 8201 and the planar moving structure 81, adjusting its center of gravity.

[0111] After the nut 2 is fixed in the nut seat 601, and the screw clamping structure 7 clamps the screw, because the ball screw pair being tested is a long screw, and the machining of the equipment cannot guarantee 100% precision, it is difficult to ensure that the centers of the nut seat 601 and the screw clamping structure 7 are on the same vertical line. Since the centers of gravity of the screw and the nut do not coincide, the axial clearance measurement results of the ball screw pair will be inaccurate.

[0112] In this application, the lead screw clamping structure 7 is mounted on the universal floating structure 8. If the centers of gravity of the lead screw 3 and the lead nut 2 are not on the same vertical line, then once the lead nut 2 is clamped, the lead screw 3 will tilt at a certain angle to the horizontal plane. Under the action of the lead screw 3's own weight, the lead screw 3, through the universal floating structure 8, causes the lead screw clamping structure 7 and the lead screw to swing together, so that the centers of gravity of the lead screw and the lead nut are automatically adjusted to a vertical line. The universal floating structure 8 in this application can realize the adjustment of the centers of gravity of the lead screw and the lead nut without manual intervention, improving the accuracy and efficiency of the system detection.

[0113] During the specific test, when the loading structure 9 applies force to the lead screw, and relative displacement occurs between the lead screw 3 and the lead nut 2, the lead nut 2 is pressed into the lead nut seat 601 by the four lever clamping structures 603. Simultaneously, an anti-rotation structure is installed in the lead nut seat 601 to ensure that the lead nut does not rotate during the test. The lead screw is clamped by the lead screw clamping structure 7, which is located on the floating plate of the universal floating structure 8. Although the base body 8202 and the top connecting plate 8203 are already fixedly connected by screws, to further ensure that the lead screw does not rotate during the test, an anti-rotation structure 8204 is added between the base body 8202 and the top connecting plate 8203. This structure includes two anti-rotation pins, which are inserted into the base body 8202 and the top connecting plate 8203 respectively, and are connected by an anti-rotation straight rod. By setting the anti-rotation structure 8204, it is further ensured that the base body 8202 and the top connecting plate 8203 will not be displaced relative to each other, thereby ensuring that the floating plate, the screw clamping mechanism and the screw can only swing and not rotate, thus ensuring the accuracy of the final measured axial clearance value.

[0114] like Figure 12 , Figure 13 and Figure 14 As shown, the lead screw clamping structure 7 includes: a floating plate 701, a fixed clamping block 702, a rotating clamping block 703, a clamping cylinder 704, and a clamping rotating shaft 705.

[0115] The floating plate 701 is horizontally installed on the top connecting plate 8203 of the omnidirectional floating structure 8;

[0116] The fixed clamping block is fixedly installed on the floating plate 701, and the clamping rotation shaft 705 is vertically installed on the floating plate 701; the output shaft of the clamping cylinder 704 is set horizontally.

[0117] The rotating clamping block 703 is movably mounted on the floating plate 701, with one end rotatably mounted on the clamping rotating shaft and the other end connected to the output shaft of the clamping cylinder.

[0118] A semi-circular first clamping arc opening is provided on the rotating clamping block 703 at the part between the clamping cylinder 704 and the clamping rotating shaft 705, on the side away from the output shaft of the clamping cylinder 704; a semi-circular second clamping arc opening is provided on the fixed clamping block 702, and the first clamping arc opening and the second clamping arc opening constitute a circular clamping opening.

[0119] A shrinkage slit is provided on the first clamping arc, and the shrinkage slits are evenly distributed along the radial direction on the first clamping arc. When elastic deformation occurs, the annular structure maintains elastic margin through the setting of the tapered sleeve shrinkage slit. One end of the shrinkage slit is open, and the shrinkage slit penetrates the rotating clamping block 703 in the thickness direction, with a length less than the width of the annular structure in which it is located. The lead screw is a round rod, and the diameter will vary for different products. There are also processing errors for the same product. Therefore, the shrinkage slit is provided to ensure that the lead screw clamping structure 7 can be more practical.

[0120] like Figure 14 As shown, the end of the fixed clamping block 702 where the second clamping arc is located is set as a horizontal U-shaped structure, with the open end facing the rotating clamping block 703. The second clamping arc is also set on the upper and lower horizontal plates of the U-shape.

[0121] The rotating clamping block 703 is configured with a U-shaped structure, with the middle horizontal plate of the U-shape protruding and its thickness being adapted to the distance between the upper and lower horizontal plates of the U-shape of the fixed clamping block 702; the U-shaped structure of the fixed clamping block 702 and the U-shaped structure of the rotating clamping block 703 constitute an interlocking plug-in structure.

[0122] Because the lead screw clamping structure 7 is set on the universal floating structure 8, in order to ensure that the lead screw does not swing too much during feeding, causing a large shift in the center of gravity of the lead screw and the lead nut, an auxiliary support structure 83 is also provided in this application. The two auxiliary support rods 8302 of the auxiliary support structure 83 support the floating plate 701 from the bottom, ensuring that the floating plate 701 remains balanced during the feeding process.

[0123] The pre-positioning structure also includes an auxiliary support structure 83, which includes a support cap 8301, an auxiliary support rod 8302, and a support rod cylinder 8303. The support caps 8301 are arranged in pairs and symmetrically around the circular clamping opening to ensure that the auxiliary support rod 8302 can horizontally support the floating plate 701. The support rod cylinder 8303 is mounted on the clamping mounting plate, and the support caps 8301 are mounted on the floating plate 701 with a positioning cavity hole at the bottom. The auxiliary support rod 8302 is vertically arranged, with its bottom connected to the output end of the support rod cylinder 8303, and a positioning tip at the top that is adapted to the positioning cavity hole.

[0124] Before loading, the default position of the auxiliary support rod 8302 is inserted into the positioning cavity hole to lock the floating plate 701 and support the floating plate 701 horizontally. After loading, when the screw clamping structure 7 clamps the screw, the support rod is started by the cylinder 8303 to pull the auxiliary support rod 8302 down out of the positioning cavity hole of the support cap 8301 and disengage from the support cap 8301, ensuring that the floating plate 701 can swing freely with the universal floating structure 8.

[0125] To ensure accurate measurements, this application also includes a counterweight structure 11. The counterweight structure 11 includes: a counterweight block 1101, a counterweight sprocket 1102, a chain 1103, and a counterweight slide rail 1104.

[0126] like Figures 1-3 As shown, the counterweight slide rail 1104 is vertically mounted on the main support 1, and two sets of counterweight sprockets 1102 are mounted at the same height, one set being mounted above the screw clamping structure 7 and the other set being mounted above the counterweight block 1101; the chain 1103 is laid on both sets of counterweight sprockets 1102, one end of the chain 1103 is connected to the counterweight block 1101, and the other end is connected to the clamping structure outer plate 907 of the loading structure 9; the counterweight block 1101 and the loading structure 9 are connected by the chain 1103.

[0127] The structure connected to the clamping structure external plate 907 and sliding up and down along the loading slide rail 902 includes: a lead screw clamping structure, a universal floating structure 8, and a partial loading structure 9. The weight of the counterweight 1101 is equivalent to the total weight of these structures. The weight of this part of the structure connected to the clamping structure external plate 907 far exceeds the measuring force required for axial clearance measurement. This application uses the counterweight 1101 to zero out the weight of this part of the structure, ensuring that the loading structure 9 applies an accurate measuring force.

[0128] After the first measurement, the clearance measuring motor stops, and the clearance measuring pen 401 returns to the non-default measurement position. The compensation measuring cylinder 501 drives the nut end face clamping seat 506 to release the pressure on the upper end face of the nut. Driven by the nut clamping cylinder, the four lever clamping structures 603 release the pressure on the top face of the nut. The nut lifting structure 609 lifts the nut, and the loading motor 901 starts. The screw is pulled up or down by the screw clamping structure 7. After adjusting the screw to the next test position, the push cylinder pulls the nut clamping part back, and the nut falls into the nut seat 601. The nut clamping cylinder drives the lever clamping structure 603 to clamp the upper end face of the nut, and the next round of axial clearance measurement can begin. In each test, the system deformation value is obtained by subtracting the measurement value of the compensation measuring pen 502 from the measurement value of the clearance measuring pen 401. After testing all preset measurement positions on the ball screw, the obtained clearance measurements are summed, and the average value is taken as the axial clearance value of the ball screw pair under test. The entire measurement process can be automatically completed based on existing PLC control technology.

Claims

1. A ball screw pair axial clearance measuring device, comprising: The loading structure and measuring structure are characterized in that they further include: a positioning structure, a universal floating structure, and a pre-positioning structure; all structures are mounted on the main support. The positioning structure includes: a nut clamping structure and a screw clamping structure; the nut clamping structure is installed above the screw clamping structure, and the screw clamping structure is installed on the universal floating structure; the pre-positioning structure is installed below the nut clamping structure. After the ball screw assembly to be tested is fed, the nut of the ball screw assembly is placed on the nut seat in the nut clamping structure, and the screw is initially positioned by the pre-positioning structure. After the screw clamping structure in the positioning structure clamps the screw, the pre-positioning structure releases the screw. Then, the nut clamping structure presses the nut into the nut seat from top to bottom. At the same time, the screw clamping structure adjusts the center of gravity of the screw based on the universal floating structure, so that the center of gravity of the nut and the screw are on the same vertical line, thus completing the positioning of the nut and the screw. The loading structure applies a measuring force to the ball screw pair to be tested, and the measuring structure measures the axial clearance of the ball screw pair to be tested. The nut clamping structure includes: a nut seat, a nut seat base plate, and a four-position lever clamping structure; The size and shape of the nut seat are adapted to the nut of the ball screw pair to be tested, and an anti-rotation structure is provided in the inner cavity of the nut seat; the nut seat is horizontally mounted on the main support through the nut seat base plate, and four lever clamping structures are arranged on the outer periphery of the nut seat; the clamping end of the lever clamping structure is located above the nut seat; The lead screw clamping structure includes: a floating plate, a fixed clamping block, a rotating clamping block, a clamping cylinder, and a clamping rotating shaft; The floating plate is horizontally mounted on the omnidirectional floating structure; The fixed clamping block is fixedly mounted on the floating plate, and the clamping rotation shaft is vertically mounted on the floating plate; the output shaft of the clamping cylinder is horizontally arranged. The rotating clamping block is movably mounted on the floating plate, with one end rotatably mounted on the clamping rotating shaft and the other end connected to the output shaft of the clamping cylinder; A semi-circular first clamping arc opening is provided on the rotating clamping block at the position between the clamping cylinder and the clamping rotating shaft, on the side away from the output shaft of the clamping cylinder; a semi-circular second clamping arc opening is provided on the fixed clamping block, and the first clamping arc opening and the second clamping arc opening constitute a circular clamping opening; The second clamping arc of the fixed clamping block is set as a horizontal U-shaped structure, with the open end facing the rotating clamping block. The second clamping arc is also set on the upper and lower horizontal plates of the U-shape. The rotating clamping block is configured as a U-shaped structure, with the middle horizontal plate of the U-shape protruding and its thickness adapted to the distance between the upper and lower horizontal plates of the fixed clamping block; the U-shaped structure of the fixed clamping block and the U-shaped structure of the rotating clamping block form an interlocking plug-in structure.

2. The axial clearance measuring device for a ball screw pair according to claim 1, characterized in that: A shrinkage slit is provided on the first clamping arc, and the shrinkage slit is evenly distributed on the first clamping arc along the radial direction; one end of the shrinkage slit is open, and the shrinkage slit penetrates the rotating clamping block in the thickness direction, with a length less than the width of the annular structure in which it is located.

3. The axial clearance measuring device for a ball screw pair according to claim 1, characterized in that: The measurement structure includes: a measuring pen structure and a compensation structure; The measuring pen structure includes: a clearance measuring pen, a positioning ball, an adjusting rod, a clearance measuring motor, a clearance measuring slide rail, a measuring bracket, a positioning frame, a measuring slide plate, and a clearance measuring lead screw; The clearance measuring motor and the clearance measuring slide rail are mounted on the main support, and the measuring slide plate is slidably mounted on the clearance measuring slide rail. The clearance measuring motor drives the measuring slide plate to slide along the clearance measuring slide rail. The measuring bracket is mounted on the measuring slide plate; the positioning portal frame is mounted below the measuring bracket with its opening facing downwards, and the measuring end of the clearance measuring pen is mounted below the crossbeam of the positioning portal frame with its measuring end facing downwards; The two ends of the adjusting rod are movably mounted on the two side walls of the positioning frame, and the positioning ball is movably fitted onto the adjusting rod; the size of the positioning ball is adapted to the size of the center hole at the top of the ball screw in the ball screw pair to be measured; there is space for vertical movement between the adjusting rod and the positioning frame, and between the adjusting rod and the positioning ball; The measuring end of the clearance measuring pen, the center of the positioning ball, and the center of the nut are located on the same vertical line; The compensation structure includes: a compensation measuring cylinder, a compensation measuring pen, a compensation portal frame, a compensation slide rail, a compensation sliding frame, a nut end face clamping seat, and a compensation test reference nut; The compensation slide rail is vertically mounted on the main support, and the compensation portal frame is mounted on the base plate of the nut seat; the compensation sliding frame is slidably connected to the compensation slide rail; the compensation measuring cylinder is mounted on the top crossbeam of the compensation portal frame and drives the compensation sliding frame to slide along the compensation slide rail. The reference nut used for compensation testing is vertically installed inside the compensation portal frame; A compensation measuring pen is installed below the compensation sliding frame, and the compensation measuring pen and the reference nut are located on the same vertical line; The end face clamping seat of the nut is installed below the compensation sliding frame. The cylindrical end face clamping seat of the nut is concentrically arranged with the nut seat and located above the nut seat.

4. The axial clearance measuring device for a ball screw pair according to claim 1, characterized in that: The loading structure includes: a loading motor, a loading slide rail, a loading lead screw, a loading nut, an S-type spring force sensor, a loading connection structure, and two sets of force transmission springs. The loading connection structure includes: a clamping structure outer plate, an upper spring plate and a lower spring plate disposed at both ends of the S-shaped spring force sensor, and a first fixing plate, a spring connecting plate, and a second fixing plate disposed from top to bottom; The loading screw and the loading slide rail are mounted parallel and vertically on the main support, the loading nut is mounted on the loading screw, and the output shaft of the loading motor is connected to the loading screw; The spring connecting plate is fixedly connected to the loading nut, the upper spring plate is connected to the spring connecting plate, and the upper and lower ends of the S-shaped spring force sensor abut against the upper spring plate and the lower spring plate, respectively. Two sets of force transmission springs are respectively provided on the upper and lower end faces of the lower top plate of the spring; the top end of the upper force transmission spring abuts against the first fixed plate and the bottom end abuts against the lower top plate of the spring; the two ends of the lower force transmission spring abut against the lower top plate of the spring and the second fixed plate, respectively. The first fixing plate, the second fixing plate, and the spring connecting plate are respectively slidably connected to the loading slide rail based on the slider; One side of the clamping structure's outer plate is connected to both the first and second fixing plates, while the other side is provided with the universal floating structure and the lead screw clamping structure.

5. The axial clearance measuring device for a ball screw pair according to claim 1, characterized in that: The omnidirectional floating structure includes: a planar moving structure and a ball joint structure; The planar moving structure includes: a planar slider, four sets of linear guides, and two sets of guide rail base plates; of the four sets of linear guides, two sets are x-axis guides, arranged in parallel on one guide rail base plate, and the other two sets are y-axis guides, arranged in parallel on another guide rail base plate; the two guide rail base plates are arranged vertically, with the upper guide rail base plate slidably mounted on the linear guides of the lower guide rail base plate based on the slider structure at the bottom; the planar slider is slidably mounted on the linear guides of the upper guide rail base plate; the lower guide rail base plate is mounted on the loading structure; The ball joint structure includes: a ball joint seat and a ball joint; the ball joint seat includes: a base body and a top connecting plate; the center of the ball joint is provided with a vertical central hole, the diameter of which is adapted to the diameter of the lead screw; The base body has a spherical cavity adapted to the size of the ball joint; the ball joint is movably installed in the spherical cavity with the central hole perpendicular to it; the base body is fixedly installed on the planar slider; the top connecting plate is provided on the upper end face of the base body; The top connecting plate and the planar slider have lead screw through holes at positions corresponding to the spherical inner cavity, which are adapted to the central hole of the ball joint; the floating plate of the lead screw clamping structure is horizontally mounted on the top connecting plate.

6. The axial clearance measuring device for a ball screw pair according to claim 1, characterized in that: The pre-positioning structure includes: a lead screw middle positioning structure and a lead screw bottom positioning structure; The bottom positioning structure of the lead screw includes: a bottom positioning cylinder and a bottom pre-positioning shaft; the middle positioning structure of the lead screw includes: a middle pre-positioning gripper.

7. The axial clearance measuring device for a ball screw pair according to claim 6, characterized in that: The pre-positioning structure also includes: an auxiliary support structure, including an auxiliary support rod, a cylinder for the support rod, and a support cap; the support caps are arranged in pairs, with the support cap and the auxiliary support rod arranged in a one-to-one ratio; the cylinder for the support rod is set on the clamping mounting plate, the support cap is set on the floating plate, and a positioning cavity is opened at the bottom; the auxiliary support rod is set vertically, with the bottom connected to the output end of the cylinder for the support rod, and a positioning tip is set at the top, the positioning tip being adapted to the positioning cavity.

8. The axial clearance measuring device for a ball screw pair according to claim 4, characterized in that: It also includes: counterweight structure; The counterweight structure includes: a counterweight block, a counterweight slide rail, a chain, and a counterweight sprocket; The counterweight slide rail is vertically mounted on the main support, and two sets of counterweight sprockets are mounted at the same height, one set being mounted above the screw clamping structure and the other set being mounted above the counterweight block. The chain is laid on two sets of counterweight sprockets. One end of the chain is connected to the counterweight block, and the other end is connected to the clamping structure outer plate of the loading structure.

9. The axial clearance measuring device for a ball screw pair according to claim 1, characterized in that: The nut clamping structure further includes: a nut lifting structure; The nut lifting structure includes: a horizontally arranged propulsion cylinder and a nut clamping part connected to the output end of the propulsion cylinder; The nut clamping part has a U-shaped structure. The closed end of the U-shaped opening is connected to the propulsion cylinder. The top horizontal bar at the U-shaped opening is the limiting end, and the bottom horizontal bar is the lifting end. The distance between the limiting end and the lifting end is adapted to the height of the bottom engagement protrusion of the nut. The nut seat has a sliding groove at each end of a diameter, and the openings of the nut clamping parts of the two nut lifting structures are arranged in the sliding grooves with the nut facing the nut direction; the height of the lifting end is greater than the depth of the sliding groove. The lifting end, away from the propulsion cylinder, is provided with an insertion guide slope. The head of the guide slope is narrower, while the side adjacent to the propulsion cylinder is wider.

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