Measuring structure for ball screw pair axial clearance measuring device

Abstract

According to the measuring structure for the ball screw pair axial clearance measuring device, the positioning ball is arranged, and the measuring position of the clearance measuring pen is positioned through the positioning ball and the center hole in the top end of the screw in the ball screw pair to be measured; a compensation structure is arranged, a reference nut is installed on a main support through a compensation n-shaped frame and a nut base bottom plate, and a compensation measuring pen and a nut end face pressing base are installed on a compensation sliding frame at the same time; the deformation value generated after the measuring device is stressed in the measuring process is detected through the displacement change between the reference nut and the measuring pen for compensation. The system deformation value is measured through the compensation structure, then the system deformation value is subtracted from the measurement result of the clearance measurement pen, it is ensured that the measurement result is more accurate, and the method is particularly suitable for measuring the axial clearance of a ball screw pair with a long screw.

Description

Technical Field

[0001] The invention relates to the technical field of ball screw pair measurement, in particular to a measurement structure for a ball screw pair axial clearance measurement device. Background Art

[0002] The ball screw pair includes: a screw and a ball nut, and is a transmission mechanism with a wide range of uses. During the use of the ball screw pair, the spiral transmission between the ball screw and the nut uses steel balls as rolling bodies to convert the rotational motion of the nut into linear motion. The axial clearance between the screw and the ball nut is a relatively important quality parameter of the ball screw pair. There are also detection devices for ball screw pairs in the prior art, such as the patent with publication number CN105973124A, which discloses a detection device for detecting the axial clearance of the ball screw pair. The nut 10 of the ball screw pair is placed in the nut fixing seat 200 for fixing, and the screw 20 of the ball screw pair is assembled with the nut 10, and the screw 20 is placed horizontally; the output shafts 310b of the first push-pull pressure gauge 300a and the second push-pull pressure gauge 300b respectively apply axial pressure to the two ends of the screw 20 to complete the measurement. However, this method of measuring by directly applying pressure at both ends of the screw horizontally is not suitable for the ball screw pair of the long screw. For example, in the ball screw pair of the long lead screw used in the steering structure of an automobile, if the horizontal placement measurement method is adopted, when the nut and the lead screw undergo relative movement, the change in the center of gravity position of the long lead screw will affect the measurement result, thereby causing inaccurate measurement result.

[0003] In order to improve the accuracy of the axial clearance measurement results of the long lead screw ball screw pair, the ball screw pair is placed vertically for axial measurement. However, because the lead screw in the ball screw pair is long, it is necessary to measure multiple locations in the lead screw separately and take the average value to obtain the axial clearance measurement result of the ball screw pair. The multiple measurement locations on the long lead screw and the long lead screw mean that the two devices themselves also have a large length. When the test force loading device applies the measurement force to the long lead screw, it will also cause the system itself to deform. The long lead screw pair is a precision device, and the deformation of this measuring device itself will cause a large error in the measurement result of the axial clearance of the ball screw pair. Summary of the invention

[0004] In order to solve the problem that the deformation of the existing measuring device itself will cause large errors in the measurement results of the axial clearance of a long lead screw ball screw pair, the present invention provides a measuring structure for a ball screw pair axial clearance measuring device, which can reduce the influence of the deformation of the measuring device system on the axial clearance measuring structure of the ball screw pair, improve the accuracy of the axial clearance measurement results of the ball screw pair, and is particularly suitable for the measurement of the axial clearance of a ball screw pair with a long lead screw.

[0005] The technical solution of the present invention is as follows: a measuring structure for a ball screw pair axial clearance measuring device, comprising: a measuring pen structure and a compensation structure; The compensation structure comprises: a compensation measuring cylinder, a measuring pen for compensation, a door frame for compensation, a slide rail for compensation, a sliding frame for compensation, a nut end face pressing seat and a reference nut for compensation test; The compensating slide rail is vertically mounted on the main bracket, and the compensating gate frame is mounted on the bottom plate of the nut seat where the nut in the ball screw pair to be tested is placed; the compensating sliding frame is slidably connected with the compensating slide rail; the compensating measuring cylinder is mounted on the top crossbeam of the compensating gate frame to drive the compensating sliding frame to slide along the compensating slide rail; The reference nut for compensation test is vertically installed on the inner side of the compensation gate frame; A compensating stylus is arranged below the compensating sliding frame, and the compensating stylus and the reference nut are located on the same vertical line; The nut end face pressing seat is installed below the compensation sliding frame, and the cylindrical nut end face pressing seat is concentrically arranged with the nut seat for placing the nut in the ball screw pair to be tested, and is located above the nut seat.

[0006] It is further characterized by: The measuring pen structure comprises: a clearance measuring pen, a positioning ball, an adjusting rod, a clearance measuring motor, a clearance measuring slide rail, a measuring bracket, a positioning gate 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 bracket, the measuring slide plate is slidably mounted on the clearance measuring slide rail, and the clearance measuring motor drives the measuring slide plate to slide along the clearance measuring slide rail; The measuring bracket is installed on the measuring slide; the positioning gate frame is installed below the measuring bracket with its opening facing downward, and the measuring end of the clearance measuring pen is installed below the crossbeam of the positioning gate frame with its measuring end facing downward; The two ends of the adjusting rod are movably mounted on the two side walls of the positioning door frame, and the positioning ball is movably mounted on the adjusting rod; the size of the positioning ball is adapted to the size of the center hole at the top end of the screw in the ball screw pair to be measured; There is space for up and down movement between the adjusting rod and the positioning door 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 circular nut seat are located on the same vertical line; The size and shape of the nut seat are adapted to the nut of the ball screw pair to be detected, and an anti-rotation structure is provided in the inner cavity of the nut seat; the nut seat is horizontally installed on the main bracket through the nut seat bottom plate, and four lever pressing structures are arranged on the outer periphery of the nut seat; the pressing end of the lever pressing structure is located above the nut seat; It 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 is in a C-shaped structure. The closed end at the opening of the C-shaped structure is connected to the propulsion cylinder. The top cross bar at the opening of the C-shaped structure is the limiting end, and the bottom cross bar is the lifting end; the distance between the limiting end and the lifting end is adapted to the height of the engaging protrusion at the bottom of the nut; On the nut seat, a chute is respectively arranged at both ends in the direction of a diameter. The nut clamping parts of the two nut lifting structures are arranged in the chute with the openings facing the nut; the height of the lifting end is higher than the depth of the chute; An insertion guiding inclined surface is arranged at one end of the lifting end away from the propulsion cylinder. The head of the guiding inclined surface is narrower, and the side adjacent to the propulsion cylinder is wider.

[0007] A measuring structure for an axial clearance measuring device of a ball screw pair provided by the present application sets a positioning ball, and positions the measuring position of the clearance measuring pen through the positioning ball and the central hole at the top end of the screw in the ball screw pair to be measured; by setting a compensation structure, the reference nut is installed on the main bracket through the compensation portal frame and the nut seat bottom plate, and the compensation measuring pen and the nut end face pressing seat are simultaneously installed on the compensation sliding frame; the deformation value generated after the measuring device itself is stressed during the measuring process is detected through the displacement change between the reference nut and the compensation measuring pen. The loading forces required for measuring ball screw pairs of different product models are different, and different loading forces will cause the entire measuring system of the measuring device to be deformed, resulting in a change in the overall rigidity of the system. The present application measures the system deformation value through the compensation structure, and then subtracts the system deformation value from the measurement result of the clearance measuring pen to ensure that the measurement result is more accurate, especially suitable for measuring the axial clearance of ball screw pairs with long screws. At the same time, the present application also sets a nut lifting structure in the nut seat to ensure that the nut can cooperate with the screw to change the test position before each test, and complete the test of the axial clearance of the ball screw pair, especially suitable for the multi-position measurement requirement of the axial clearance of long screw ball screw pairs. Brief Description of the Drawings

[0008] Figure 1 It is a schematic structural diagram of the front view of the axial clearance measuring device of the ball screw pair; Figure 2 It is a schematic structural diagram of the left view of the axial clearance measuring device of the ball screw pair; Figure 3 It is a schematic diagram of the structure of the ball screw pair axial clearance measuring device from the rear view; Figure 4 It is a schematic diagram of the main view of the measuring structure and the nut pressing structure; Figure 5 It is a schematic diagram of the structure of the measuring pen from the right side; Figure 6 This is a schematic diagram of the effect of the nut holder; Figure 7 It is a schematic structural diagram of a cross-section of a positioning ball; Figure 8 It is a structural diagram of the nut lifting structure; Fig. 9 It is the main structural diagram of the loading structure; Fig.10 This is a schematic diagram of the left view of the loading structure. Fig.11 It is a schematic diagram of the three-dimensional effect of the clamping structure and the loading structure; Fig.12 It is a structural schematic diagram of the main view of the clamping structure; Fig.13 It is a schematic diagram of the structure of the clamping structure from a top view; Fig.14 It is a structural schematic diagram of the left view of the clamping structure; Fig.15 This is a perspective rendering of the universal floating structure; Fig.16 It is a schematic diagram of the cross-section effect of the nut lifting structure and the nut seat. DETAILED DESCRIPTION

[0009] The present application includes a measuring structure for a ball screw pair axial clearance measuring device, which is installed on a Figure 1~Figure 3 The axial clearance measuring device of the ball screw pair shown in the figure comprises: 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 bracket 1.

[0010] The positioning mechanism includes: a nut pressing structure 6 and a screw rod clamping structure 7. The measuring structure includes: a measuring pen structure 4 and a compensation structure 5; the pre-positioning structure includes: a screw rod middle positioning structure 12 and a screw rod bottom positioning structure 10. The nut pressing structure 6 is installed above the screw rod clamping structure 7, and the screw rod clamping structure 7 is installed on the universal floating structure 8.

[0011] The bottom positioning structure 10 of the screw includes: a bottom positioning cylinder 1002, a bottom pre-positioning shaft 1001 and a bottom slide rail 1003; the middle positioning structure 12 of the screw includes: a middle pre-positioning jaw. Both screw pre-positioning structures are installed below the nut clamping structure 6, and the middle pre-positioning jaw is set in the middle position below the nut clamping structure 6. The bottom positioning structure 10 of the screw is set on the main bracket 1, 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 screw is set on the bottom pre-positioning shaft 1001 to ensure that the screw 3 can be vertically supported to complete the initial positioning of the screw 3, while preventing the nut 2 and the screw 3 from detaching. 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.

[0012] After the ball screw pair to be tested is loaded, the nut 2 of the ball screw pair is placed on the nut seat 601 in the nut clamping structure 6, and the screw 3 passes through the nut seat 601, the middle pre-positioning jaw 12, the screw clamping structure 7, and the universal floating structure 8 from top to bottom, and the bottom end of the screw 3 falls on the bottom pre-positioning shaft 1001. The screw 3 is supported by the bottom pre-positioning shaft 1001 and the nut seat 601. After the initial positioning of the position of the screw 3 is achieved, the middle pre-positioning jaw 12 is started to clamp the middle part of the screw 3; after the middle pre-positioning jaw 12 is grasped, the bottom positioning cylinder 1002 drives the bottom pre-positioning shaft 1001 downward to disengage from the bottom of the screw 3.

[0013] Then, after the screw rod 3 is clamped by the screw rod clamping structure 7 in the positioning structure, the middle pre-positioning claw 12 releases the middle part of the screw rod 3; then the nut clamping structure 6 is driven to press the nut 2 from top to bottom in the nut seat 601. While the nut 2 is pressed, the screw rod clamping structure 7 adjusts the center of gravity of the screw rod based on the universal floating structure 8, so that the center of gravity of the nut 2 and the screw rod 3 are located on the same vertical line, thereby completing the positioning of the nut 2 and the screw rod 3.

[0014] Finally, the measuring force is applied to the screw 3 in the ball screw pair to be tested through the loading structure 9, and the axial clearance of the ball screw pair to be tested is measured through the measuring structure. During the measurement process, the compensation stylus 502 in the compensation structure 5 simultaneously measures the deformation of the entire measuring system under the action of the measuring force, and finally the system deformation is subtracted from the measured value of the clearance stylus 401 to obtain the value of this measurement.

[0015] like Figure 4~Figure 7 As shown, the nut pressing structure 6 includes: a nut seat 601, a nut seat bottom plate 602 and a four-station lever pressing structure 603.

[0016] 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, and a nut anti-rotation structure is arranged in the inner cavity of the nut seat 601. Specifically, the nut anti-rotation structure engages with the structure of 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 bracket 1 through the nut seat bottom plate 602, and four lever clamping structures 603 are arranged on the outer periphery of the nut seat 601; the clamping end of the lever clamping structure 603 is located above the nut seat 601.

[0017] 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 arranged on the nut seat bottom plate 602; the clamping cylinder 6031 is installed on the nut seat bottom plate 602, the cylinder output end is vertically connected to the vertical rod of the L-shaped tension rod 6032, the cross bar of the L-shaped tension rod 6032 is hinged to the lever support rod 6034 through the fulcrum pin 6033; a clamping block is arranged at one end of the cross bar of the L-shaped tension rod 6032 facing the nut seat 601. When the nut in the nut seat 601 needs to be clamped, the nut clamping cylinder 6031 pushes the vertical rod of the tension rod 6032 upward, and the tension rod 6032 rotates with the fulcrum pin as the fulcrum, and the clamping block presses the upper end surface of the nut 3 downward.

[0018] The lever pressing structure 603 is evenly arranged outside the circumference of the nut holder 601 to ensure that uniform pressure can be applied to the nut in the nut holder 601 and that the nut will not deflect during the measurement process, thereby ensuring the accuracy of the measurement result.

[0019] 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 gate frame 407, a measuring slide plate 408, a clearance measuring lead screw 409 and a clearance nut 410.

[0020] The clearance measuring motor 404 and the clearance measuring slide rail 405 are installed on the main bracket 1, the measuring slide plate 408 is slidably installed on the clearance measuring slide rail 405, and the measuring slide plate 408 is installed on the clearance nut 410; the clearance measuring motor 404 drives the clearance nut 410 to move up and down through the clearance measuring lead screw 409, and then drives the measuring slide plate 408 to slide along the clearance measuring slide rail 405.

[0021] The measuring bracket 406 is installed on the measuring slide plate 408, the positioning gate frame 407 is installed below the measuring bracket 406 with its opening facing downward, and the measuring end of the clearance measuring pen 401 is installed below the crossbeam of the positioning gate frame 407 with its measuring end facing downward; the two ends of the adjusting rod 403 are movably installed on the two side walls of the positioning gate frame 407, and the positioning ball 402 is movably mounted on the adjusting rod 403; the size of the positioning ball 402 is adapted to the size of the center hole at the top end of the screw in the ball screw pair to be measured; there is space for upward and downward movement between the adjusting rod 403 and the positioning gate frame 407, and between the adjusting rod 403 and the positioning ball 402.

[0022] The measuring end of the clearance measuring pen 401, the center of the positioning ball 402 and the center of the nut seat 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 nut and the center of gravity of the screw rod are located on the same vertical line during the measurement process, thereby ensuring that the clearance between the nut and the screw rod can be accurately measured.

[0023] The compensation structure 5 includes: a compensation measuring cylinder 501, a compensation measuring pen 502, a compensation gate frame 503, a compensation slide rail 504, a compensation sliding frame 505, a nut end face pressing seat 506, and a compensation test reference nut 507; the compensation slide rail 504 is vertically installed on the main bracket 1, and the compensation gate frame 503 is installed on the nut seat bottom plate 602; the compensation sliding frame 505 is slidably connected with the compensation slide rail 504; the compensation measuring cylinder 501 is installed on the top crossbeam of the compensation gate frame 503, and the drive The dynamic compensation sliding frame 505 slides along the compensation sliding rail 504; the reference nut 507 for compensation test is vertically installed on the inner side of the compensation gate frame 503 based on the nut mounting cross plate 508; the compensation measuring pen 502 is arranged below the compensation sliding frame 505, and the compensation measuring pen 502 and the reference nut 507 are located on the same vertical line; the nut end face pressing seat 506 is installed below the compensation sliding frame 505, and the cylindrical nut end face pressing seat 506 is concentrically arranged with the nut seat 601 and is located above the nut seat 601.

[0024] Install the reference nut 507 on the main bracket 1 through the compensation gate frame 503 and the nut seat bottom plate 602, and install the compensation measuring pen 502 and the nut end face pressing seat 506 on the compensation sliding frame 505 at the same time; when measuring, press the nut end face pressing seat 506 against the top end surface of the nut, and the compensation measuring pen 502 contacts the upper end surface of the reference nut 507, which is the 0 value position.

[0025] The compensating stylus 502 is installed on the main bracket 1 through the compensating sliding frame 505 and the compensating sliding rail 504, and the reference nut 507 is installed on the nut base plate 602 through the compensating gate frame 503. The nut is set on the nut base plate 602 through the nut base 601. The test force applied to the screw by the loading structure 9 is transmitted to the nut base plate 602 after the nut is subjected to the force. If the nut base 601, the nut base plate 602 and other structures are deformed after being subjected to the force, the deformation will be reflected on the reference nut 507. When the position of the reference nut 507 changes, the measurement value of the compensating stylus 502 will change. The deformation value of the system itself after being subjected to the force during the measurement process is detected through the displacement change between the reference nut 507 and the compensating stylus 502.

[0026] The clearance measuring pen 401 is initially in contact with the positioning ball 402, and the initial value of the measuring pen is reset to zero; after the measurement starts, the clearance measuring motor 404 drives the measuring slide 408 to slide along the clearance measuring slide rail 405 in the vertical direction, driving the adjusting rod 403 and the positioning ball 402 movably mounted on the adjusting rod 403 to move to the center hole at the top of the screw in the ball screw pair to be measured, and the bottom position of the positioning ball 402 is fixed. The clearance measuring motor 404 continues to drive the adjusting rod 403 downward, so that the adjusting rod 403 and the positioning ball 402 are separated. When the adjusting rod 403 continues to move downward, the measurement value of the clearance measuring pen 401 changes. When the measurement value detected by the measuring pen changes to the preset value, indicating that the measuring pen has reached the measurement position, the clearance measuring motor 404 stops. The ball screw pair in the present application is a precision device whose axial clearance is measured in microns, so a high-precision sensor is required. In the present embodiment, the clearance measuring pen 401 and the compensation measuring pen 502 are implemented based on displacement sensors, such as optical-magnetic high-precision displacement sensors. The specific installation method and detection method of the displacement sensor can be implemented based on any displacement sensor in the prior art.

[0027] After the gap measurement motor stops, the compensation measurement cylinder 501 starts, driving the nut end face pressing seat 506 and the compensation measuring pen 502 to slide downward along the compensation slide rail 504 until the nut end face pressing seat 506 presses onto 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.

[0028] Among them, the reference nut 507 is vertically installed on the inner side of the compensation gate frame 503 through the nut mounting cross plate 508. The reference nut 507 is threadedly connected to the nut mounting cross plate 508. The height position of the reference nut 507 can be adjusted according to specific measurement requirements, and is suitable for ball screw pairs of different sizes.

[0029] The loading forces required for measuring ball screw pairs of different product models are different. Different loading forces will cause deformation of the entire system of the measuring device, resulting in changes in the overall rigidity of the system. In this application, the compensation structure 5 measures the system deformation value, and then subtracts the system deformation value from the measurement result of the backlash measuring pen 401 to ensure more accurate measurement results.

[0030] During each measurement, the screw rod in the ball screw pair is lifted once and then pulled down once through the loading structure 9. The two applications of force will cause the backlash measuring pen 401 to have two measurement values, and the difference between the two measurement values is the backlash detection value for this time; similarly, the difference between the two measurement values detected by the compensation measuring pen 502 during the two applications of force is the system deformation value for this time.

[0031] Since the screw rod in the ball screw pair to be measured in this application is a long screw rod, during specific implementation, the axial clearance needs to be tested at different positions of the long screw rod respectively, and finally the average value is calculated using multiple measurement values. Therefore, after each measurement, the next preset measurement position needs to be adjusted. During specific implementation, after the previous measurement is completed, the nut 2 needs to be lifted and then the position of the screw rod 3 is adjusted. Since the rotation of the nut needs to be prevented when measuring the axial clearance, an anti-rotation structure is provided in the nut seat 601 of this application. When adjusting the position of the screw rod, the nut needs to be rotated, so this application also provides a nut lifting structure 609 in the nut pressing structure 6.

[0032] As Figure 7 and Figure 8 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; The nut clamping part is a C-shaped structure. The closed end of the C-shaped opening is connected to the propulsion cylinder, the top cross bar at the opening of the C-shaped is the limiting end 6093, and the bottom cross bar is the lifting end 6094; the distance between the limiting end 6093 and the lifting end 6094 is adapted to the height of the engaging protrusion 201 at the bottom of the nut, specifically as Fig.16 shown.

[0033] On the nut seat 601, a chute 6010 is respectively arranged at both ends in the direction of a diameter. The nut clamping parts of the two nut lifting structures 609 are arranged in the chute with the openings facing the nut direction; the height of the lifting end 6094 is higher than the depth of the chute; An insertion guiding slope 6095 is arranged at the end of the lifting end 6094 away from the propulsion cylinder. The head of the guiding slope 6095 is narrower and the side adjacent to the propulsion cylinder is wider.

[0034] Initially, the nut clamping part is in the slide groove, located at the position of the original nut, and does not hinder the measurement process. When the nut needs to be lifted, the thrust cylinder is started, and when the nut lifting end 6094 is pushed along the slide groove to the inner cavity direction of the nut seat 601, the head of the guide slope 6095 is narrower and will be directly inserted into the bottom of the nut. The thrust cylinder continues to push, and the engaging protrusion at the bottom of the nut completely enters the nut clamping part; because the height of the lifting end 6094 is higher than the depth of the slide groove, the bottom of the nut leaves the bottom of the nut seat 601 and will not be hindered 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 started, and the screw rod is pulled up or down through the screw rod clamping structure 7, and the nut rotates on the end face of the nut lifting end 6094 to adjust the test position of the screw rod. The limiting end 6093 of the nut clamping part is used to prevent the nut from being displaced in the height direction. The setting of the limiting end 6093 ensures that the nut will not separate from the nut clamping part, but will rotate in place to change the test position where the screw rod and the nut contact.

[0035] like Fig. 9 , Fig.10 and Fig.11 As shown, the loading structure 9 includes: a loading motor 901, a loading slide rail 902, a loading screw rod 903, a loading nut 904, an S-shaped spring force sensor 905, a loading connection structure, and two groups of four force transmission springs 906. The loading connection structure includes: a clamping structure external plate 907, a spring upper top plate 908 and a spring lower top plate 909 arranged at both ends of the S-shaped spring force sensor 905, and a first fixing plate 910, a spring connection plate 911, and a second fixing plate 912 arranged from top to bottom.

[0036] The loading screw rod 903903 and the loading slide rail 902 are installed on the main bracket 1 in parallel and vertically, the loading nut 904 is installed on the loading screw rod 903, and the output shaft of the loading motor 901 is connected to the loading screw rod 903.

[0037] The spring connecting plate 911 is arranged between the first fixing plate 910 and the second fixing plate 912; the spring connecting plate 911 is fixedly connected to the loading nut 904, the spring upper top plate 908 is connected to the spring connecting plate 911, and the upper and lower ends of the S-shaped spring force sensor 905 are respectively against the spring upper top plate 908 and the spring lower top plate 909.

[0038] On the upper and lower end faces of the lower spring top plate 909, two groups of a total of 4 force-conducting springs 906 are respectively arranged; the tops of the 2 upper force-conducting springs abut against the first fixed plate 910, and the bottoms abut against the lower spring top plate 909; the two ends of the lower force-conducting spring 906 respectively abut against the lower spring top plate 909 and the second fixed plate 912. Specifically, a first cross plate 913 is installed on the first fixed plate 910, and a second cross plate 914 is installed on the second fixed plate 912; two groups of force-conducting springs 906 are respectively arranged on the upper and lower end faces of the lower spring top plate 909; the two ends of the lower force-conducting spring 906 respectively abut against the lower spring top plate 909 and the second cross plate 914; the tops of the upper force-conducting springs respectively abut against the first cross plate 913, and the bottoms abut against the lower spring top plate 909.

[0039] The first fixed plate 910, the second fixed plate 912, and the spring connection plate 911 are respectively slidably connected to the loading slide rail 902 based on the slider.

[0040] One side of the clamping structure external connection plate 907 is connected to both the first fixed plate 910 and the second fixed plate 912 at the same time, and a universal floating structure 8 and a screw rod clamping structure 7 are arranged on the other side. The clamping structure external connection plate 907 is in a C shape, and the two protruding structures at the open end are respectively connected to the first fixed plate 910 and the second fixed plate 912. The clamping structure external connection plate 907 is not directly connected to the middle spring connection plate 911 to ensure accurate force conduction.

[0041] The upper and lower ends of the S-shaped spring force sensor 905 respectively abut against the upper spring top plate 908 and the lower spring top plate 909. The top end of the S-shaped spring force sensor 905 is connected to the spring connection plate 911 through the upper spring top plate 908. The bottom end of the S-shaped spring force sensor 905 is connected to both the first fixed plate 910 and the second fixed plate 912 through the lower spring top plate 909 and two groups of force-conducting springs 906, and then connected to the clamping structure external connection 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 connection plate 911 to move, and through the upper spring top plate 908, the S-shaped spring force sensor 905, the lower spring top plate 909, the first fixed plate 910, the second fixed plate 912, and the clamping structure external connection plate 907, the force is conducted to the screw rod clamping structure 7, that is, the test force is applied to the screw rod 3 in the ball screw pair to be detected in the vertical direction. In this application, the S-shaped spring force sensor 905 can simultaneously detect and conduct forces in multiple directions to ensure the accuracy of the detection results. In this period, 4 force-conducting springs 906 and the S-shaped spring force sensor 905 are used to conduct the force to ensure that the test force applied by the loading motor can be smoothly conducted to the clamping structure.

[0042] When the loading structure 9 needs to apply force to the screw rod, the loading motor is started. Assuming that the loading screw rod 903 rotates to drive 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, and the spring connecting plate 911 drives the spring upper top plate 908 to pull the S-type spring force sensor 905 upward. The S-type spring force sensor 905 drives the spring lower top plate 909 to move upward. The spring lower top plate 909 pushes up the two sets of force transmission springs 906 above. The upper force transmission spring 906 pushes up the first fixed plate 910. The first fixed plate 910 and the second fixed plate 912 are fixedly connected by the clamping structure external plate 907. When the two slide upward along the loading slide rail 902, the clamping structure external plate 907 drives the universal floating structure 8 and the clamping structure to move upward, that is, an upward force is applied to the screw rod.

[0043] When the loading motor drives the loading nut 904 to move downward in the vertical direction, the spring connecting plate 911 drives the spring upper plate 908 to press downward on the S-shaped spring force sensor 905, and the S-shaped spring force sensor 905 drives the spring lower plate 909 to move downward, and the spring lower plate 909 applies force downward to the two groups of force transmission springs 906 below, and the two groups of force transmission springs 906 below apply force downward to press the second fixed plate 912, and the second fixed plate 912, the first fixed plate 910 and the clamping structure external plate 907 slide downward along the loading slide rail 902, then the loading structure 9 applies a downward force to the screw rod.

[0044] like Fig.12 , Fig.13 and Fig.14 As shown, the universal floating structure 8 includes: a planar moving structure 81 and a spherical joint structure 82 .

[0045] The plane moving structure 81 includes: a plane slider 8101, 4 groups of linear guide rails 8102 and two groups of guide rail base plates 8103; of the 4 groups of linear guide rails 8102, two groups are x-axis direction guide rails, which are arranged in parallel on one guide rail base plate 8103, and the other two groups are y-axis direction guide rails, which are arranged in parallel on another guide rail base plate 8103; the two guide rail base plates 8103 are arranged up and down, and the bottom of the upper guide rail base plate 8103 is slidably mounted on the linear guide rail 8102 of the lower guide rail base plate 8103 based on the slider structure; the plane slider 8101 is slidably mounted on the linear guide rail 8102 located 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 through the clamping mounting plate 8104. The present application realizes the arbitrary movement of the screw clamping structure 7 in the x direction and the y direction through the plane moving structure 81.

[0046] like Fig.15As shown, the spherical joint structure 82 includes: a ball joint 8201 and a ball joint seat. A vertical center hole is set at the center of the ball joint 8201, and the diameter of the center hole is adapted to the diameter of the screw rod. The ball joint seat includes: a base body 8202 and a top connecting plate 8203. A spherical inner cavity adapted to the size of the ball joint 8201 is opened in the inner cavity of the base body 8202; the ball joint 8201 is movably installed in the spherical inner cavity in a form of a vertical center hole; the base body 8202 is fixedly installed on the plane slider 8101; the top connecting plate 8203 is set on the upper end surface of the base body 8202; the top connecting plate 8203 and the plane slider 8101 are provided with a screw rod through hole adapted to the center hole of the ball joint 8201 at the position corresponding to the spherical inner cavity. The ball joint 8201 slides freely in the spherical inner cavity of the ball joint seat, ensuring that the screw rod 3 can swing at any angle based on the ball joint 8201 and the plane moving structure 81 to adjust the center of gravity.

[0047] After the nut 2 is fixed in the nut seat 601 and the screw clamping structure 7 bites the screw, because the ball screw pair being tested is a long screw and the machining of the equipment cannot ensure 100% accuracy, it is difficult to ensure that the centers of the nut seat 601 and the screw clamping structure 7 are 100% on the same vertical line, and the center of gravity of the screw and the nut do not coincide, which will cause inaccurate axial clearance measurement results of the ball screw pair.

[0048] In the present application, the screw rod clamping structure 7 is arranged on the universal floating structure 8. If the center of gravity of the screw rod 3 and the nut 2 are not on the same vertical line, once the nut 2 is pressed, the screw rod 3 will be tilted at a certain angle with the horizontal plane. Then, under the action of the self-weight of the screw rod 3, the screw rod 3 swings the screw rod clamping structure 7 and the screw rod together through the universal floating structure 8, so that the center of gravity of the screw rod and the nut are automatically adjusted to a vertical line. The universal floating structure 8 in the present application can realize the center of gravity adjustment of the screw rod and the nut without manual intervention, thereby improving the accuracy of system detection and the detection efficiency of the system.

[0049] During the specific test, when the loading structure 9 applies force to the screw rod and relative displacement occurs between the screw rod 3 and the nut 2, the nut 2 is pressed in the nut seat 601 by the four lever clamping structures 603, and an anti-rotation structure is provided in the nut seat 601 to ensure that the nut will not rotate during the test. The screw rod is clamped by the screw rod clamping structure 7, but the screw rod clamping structure 7 is provided on the floating plate of the universal floating structure 8. Although the base body 8202 and the top connecting plate 8203 are fixedly connected by screws, in order to further ensure that the screw rod does not rotate during the test, an anti-rotation structure 8204 is provided between the base body 8202 and the top connecting plate 8203, including: two anti-rotation pins, which are respectively inserted into the base body 8202 and the top connecting plate 8203, and the two anti-rotation pins are connected by an anti-rotation straight rod. The anti-rotation structure 8204 is provided to further ensure that the base body 8202 and the top connecting plate 8203 will not undergo relative displacement, thereby ensuring that the floating plate, the screw clamping mechanism and the screw can only swing but not rotate, thereby ensuring the accuracy of the final measured axial clearance value.

[0050] like Fig.12 , Fig.13 and Fig.14 As shown, the screw rod 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 .

[0051] The floating plate 701 is horizontally mounted on the top connecting plate 8203 of the universal floating structure 8; The clamping fixed block is fixedly mounted on the floating plate 701 , the clamping rotating shaft 705 is vertically mounted on the floating plate 701 ; and the output shaft of the clamping cylinder 704 is horizontally arranged.

[0052] The rotating clamping block 703 is movably arranged on the floating plate 701, one end of which is rotatably mounted on the supporting rotating shaft, and the other end of which is connected to the supporting cylinder output shaft.

[0053] A semicircular first clamping arc is set on the rotating clamping block 703, at a position between the clamping cylinder 704 and the clamping rotating shaft 705, away from the output shaft of the clamping cylinder 704; a semicircular second clamping arc is set on the fixed clamping block 702, and the first clamping arc and the second clamping arc constitute a circular clamping opening.

[0054] A shrinkage joint is provided on the first clamping arc opening. The shrinkage joints are evenly arranged along the radial direction on the first clamping arc opening. When elastic deformation occurs, the elastic margin of the annular structure is maintained through the setting of the shrinkage joints of the tapered sleeve. One end of the shrinkage joint is open. The shrinkage joint penetrates the rotary clamping block 703 in the thickness direction, and its length is less than the width of the annular structure where it is located. The lead screw is a round rod. The diameters of different products will vary, and there are also machining errors for the same product. Therefore, shrinkage joints are opened to ensure that the lead screw clamping structure 7 can be more practical.

[0055] As Fig.14 shown, the end of the second clamping arc opening of the fixed clamping block 702 is set as a horizontal C-shaped structure, and the open end faces the rotary clamping block 703. The second clamping arc opening is also arranged on the upper and lower horizontal plates of the C-shaped structure. The rotary clamping block 703 is set as a E-shaped structure. The middle horizontal plate of the E-shaped structure protrudes and its thickness is adapted to the distance between the upper and lower horizontal plates of the C-shaped structure of the fixed clamping block 702. The C-shaped structure of the fixed clamping block 702 and the E-shaped structure of the rotary clamping block 703 form an interlocking plug-in structure.

[0056] Since the lead screw clamping structure 7 is arranged on the universal floating structure 8, in order to ensure that there will be no large swing when the lead screw is loaded, resulting in a large offset of the center of gravity of the lead screw and the nut, an auxiliary support structure 83 is also provided in this application. Through the two auxiliary support rods 8302 of the auxiliary support structure 83, the floating plate 701 is supported from the bottom to ensure that the floating plate 701 remains balanced during the loading process.

[0057] The pre-positioning structure further includes: an auxiliary support structure 83. The auxiliary support structure 83 includes: a support cap 8301, an auxiliary support rod 8302, and a cylinder for the support rod 8303. The support caps 8301 are arranged in pairs and symmetrically arranged with the circular clamping opening as the center to ensure that the auxiliary support rods 8302 can horizontally support the floating plate 701. The cylinder for the support rod 8303 is arranged on the clamping mounting plate, and the support cap 8301 is arranged on the floating plate 701 with a positioning cavity hole opened at the bottom. The auxiliary support rods 8302 are vertically arranged, the bottom is connected to the output end of the cylinder for the support rod 8303, and the top is provided with a positioning tip, and the positioning tip is adapted to the positioning cavity hole.

[0058] 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 horizontally support the floating plate 701. After loading, when the lead screw clamping structure 7 clamps the lead screw, the cylinder for the support rod 8303 is activated to pull the auxiliary support rod 8302 downward out of the positioning cavity hole of the support cap 8301 and disengage from the support cap 8301 to ensure that the floating plate 701 can swing arbitrarily with the universal floating structure 8.

[0059] In order to ensure the accuracy of the measured value, a counterweight structure 11 is also provided in the present application. The counterweight structure 11 includes: a counterweight block 1101, a counterweight sprocket 1102, a chain 1103 and a counterweight slide rail 1104.

[0060] like Figures 1 to 3 As shown, the counterweight slide rail 1104 is vertically arranged on the main bracket 1, and two groups of counterweight sprockets 1102 are arranged at the same height, one group is arranged above the screw clamping structure 7, and the other group is arranged above the counterweight block 1101; the chain 1103 is laid on the two groups of counterweight sprockets 1102 at the same time, one end of the chain 1103 is connected to the counterweight block 1101, and the other end is connected to the clamping structure external plate 907 of the loading structure 9; the counterweight block 1101 and the loading structure 9 are connected by the chain 1103.

[0061] The structure connected to the clamping structure external plate 907 and sliding up and down along the loading slide rail 902 as a whole includes: a screw clamping structure, a universal floating structure 8, and a partial loading structure 9. The weight of the counterweight block 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 in the device far exceeds the measurement force required for axial clearance measurement. The present application uses the counterweight block 1101 to balance the weight of this part of the structure to zero, ensuring that the loading structure 9 applies an accurate measurement force.

[0062] After the first measurement, the gap measurement motor stops and takes the clearance measuring pen 401 upward to return to the non-measurement default position, the compensation measuring cylinder 501 drives the nut end face pressing seat 506 to release the pressure on the upper end face of the nut, and the four lever pressing structures 603 release the pressure on the top face of the nut under the drive of the nut pressing cylinder, and the nut lifting structure 609 lifts the nut, and the loading motor 901 is started, and the screw rod is pulled up or down through the screw rod clamping structure 7, and after adjusting the screw rod to the next test position, the thrust cylinder pulls the nut clamping part back, and the nut falls into the nut seat 601. After the nut pressing cylinder drives the lever pressing structure 603 to press the upper end face of the nut, the next round of axial clearance measurement can be started again. In each test, the current measurement value is obtained by subtracting the system deformation value obtained by the compensation measuring pen 502 from the measurement value of the clearance measuring pen 401. After all the preset measuring positions on the screw are tested, the clearance measurement values ​​obtained each time are added together and the average value is taken, which is the axial clearance value of the ball screw pair to be tested. The entire measurement process can be automatically completed based on the PLC control technology in the prior art.

Claims

1. A measuring structure for measuring the axial clearance of a ball screw pair, comprising: Probe structure and compensation structure; The compensation structure includes: a compensation measurement cylinder, a compensation probe, a compensation portal frame, a compensation slide rail, a compensation sliding frame, a nut end face pressing seat, and a reference nut for compensation testing; The compensation slide rail is vertically installed on the main bracket, and the compensation portal frame is installed on the nut seat bottom plate of the nut in the ball screw pair to be detected; the compensation sliding frame is slidably connected to the compensation slide rail; the compensation measurement cylinder is installed on the top cross beam of the compensation portal frame to drive the compensation sliding frame to slide along the compensation slide rail; The reference nut for compensation testing is vertically installed inside the compensation portal frame; A compensation probe is arranged below the compensation sliding frame, and the compensation probe and the reference nut are on the same vertical line; The nut end face pressing seat is installed below the compensation sliding frame, and the cylindrical nut end face pressing seat is concentric with the nut seat of the nut in the ball screw pair to be detected and is located above the nut seat; 2. According to claim 1, a measuring structure for measuring the axial clearance of a ball screw pair, characterized in that: The probe structure includes: a backlash probe, a positioning ball, an adjusting rod, a motor for backlash measurement, a slide rail for backlash measurement, a measurement bracket, a positioning portal frame, a measurement slide plate, and a lead screw for backlash measurement; The motor for backlash measurement and the slide rail for backlash measurement are installed on the main bracket, the measurement slide plate is slidably installed on the slide rail for backlash measurement, and the motor for backlash measurement drives the measurement slide plate to slide along the slide rail for backlash measurement; The measurement bracket is installed on the measurement slide plate; the positioning portal frame is installed below the measurement bracket with the opening facing downwards, and the measurement end of the backlash probe is installed below the cross beam of the positioning portal frame with the measurement end facing downwards; Both ends of the adjusting rod are movably installed on the two side walls of the positioning portal frame, and the positioning ball is movably sleeved on the adjusting rod; the size of the positioning ball is adapted to the size of the central hole at the top end of the screw in the ball screw pair to be measured; 3. The measuring structure for measuring the axial clearance of a ball screw pair according to claim 2, characterized in that: There is a space for up and down movement between the adjusting rod and the positioning portal frame, and between the adjusting rod and the positioning ball; 4. The measuring structure for measuring the axial clearance of a ball screw pair according to claim 2, characterized in that: The measurement end of the backlash probe, the center of the positioning ball, and the center of the circular nut seat are on the same vertical line; 5. The measuring structure for measuring the axial clearance of a ball screw pair according to claim 1, characterized in that: The size and shape of the nut seat are adapted to the nut of the ball screw pair to be detected, and an anti-rotation structure is arranged in the inner cavity of the nut seat; the nut seat is horizontally installed on the main bracket through the nut seat bottom plate, and four lever pressing structures are arranged on the outer periphery of the nut seat; the pressing end of the lever pressing structure is located above the nut seat; 6. The measuring structure for measuring the axial clearance of a ball screw pair according to claim 5, characterized in that: It 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 is of a U-shaped structure, the closed end at the opening of the U-shaped structure is connected to the propulsion cylinder, the top cross bar at the opening of the U-shaped structure is the limiting end, and the bottom cross bar is the lifting end; the distance between the limiting end and the lifting end is adapted to the height of the clamping protrusion at the bottom of the nut; A chute is respectively arranged at both ends in the direction of a diameter on the nut seat, and the nut clamping parts of the two nut lifting structures are arranged in the chute with the openings facing the nut; the height of the lifting end is higher than the depth of the chute; An insertion guide slope is arranged at one end of the lifting end away from the propulsion cylinder. The head of the guide slope is narrower, and the side adjacent to the propulsion cylinder is wider.

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