A vertical micro-planet roller screw pair stroke error test bench

Abstract

The present application relates to the technical field of screw pair performance testing, particularly to a vertical micro small planetary roller screw pair stroke error test bench, which comprises a vertical bed body, a guide rail installed on the vertical bed body, a headstock connected to the bed body arranged on the top of the vertical bed body, a pneumatic chuck arranged on the headstock, a round grating coaxially installed on the main shaft of the pneumatic chuck, the round grating being used for measuring theoretical angular displacement, a tailstock installed on the guide rail, the pneumatic chuck and the tailstock being used for double-end overhanging clamping positioning of the non-threaded round end face of the measured screw pair, the guide rail being used for slidable positioning of a bearing platform, and a micro motion measuring platform arranged on the upper part of the bearing platform. The vertical micro small planetary roller screw pair stroke error test bench solves the problem that the traditional double centers are difficult to machine a center hole and position in a micro small size end face by clamping the non-threaded round end face of the measured screw pair at both ends through the pneumatic clamping device and the tailstock.

Description

Technical Field

[0001] This invention relates to the field of ball screw performance testing technology, and in particular to a vertical miniature planetary roller ball screw stroke error test bench. Background Technology

[0002] Miniature planetary roller screw pairs, as linear transmission components with high load capacity, long service life, and high precision, play a crucial role in high-end equipment such as precision instrument manufacturing, medical devices, and aerospace. Their stroke error is a core indicator for measuring transmission accuracy, directly determining the positioning accuracy and operational stability of the equipment. Therefore, accurate extraction and evaluation of the stroke error of miniature planetary roller screw pairs is of great significance.

[0003] Currently, horizontal testing devices are commonly used in the industry to test the stroke error of lead screw pairs. Traditional testing equipment typically uses double centers to support the center holes at both ends of the lead screw for positioning. However, for miniature planetary roller lead screw pairs, the extremely small shaft diameter makes machining standard center holes on the end faces extremely difficult, and machining errors directly affect positioning accuracy. Furthermore, the structural strength of the tiny end faces is weak and cannot withstand the axial clamping force of the double centers. Forcing clamping with double centers not only fails to guarantee coaxiality but also easily causes structural deformation at the ends of the tiny parts, thus introducing additional measurement errors.

[0004] On the other hand, in dynamic testing, to obtain the true full-stroke error curve, the axial backlash of the lead screw pair must be eliminated. Traditional horizontal devices typically rely on applying a horizontal mechanical preload to eliminate backlash. However, on miniature lead screw pairs under test, horizontal mechanical loading easily leads to uneven internal forces, causing the preload to concentrate on one side of the transmission surface. This uneven force introduces additional mechanical interference, altering the original operating state of the lead screw pair under test, resulting in measurement results that cannot accurately reflect the transmission performance of the miniature lead screw pair, thus reducing measurement accuracy. Summary of the Invention

[0005] The technical problem to be solved by this invention is to address the issue that traditional horizontal equipment with double centers cannot clamp micro-sized ball screws, and that mechanical axial preload leads to unilateral accumulation of preload force and uneven force distribution, resulting in low accuracy of stroke error measurement and difficulty in meeting the high-precision, full-stroke error testing requirements of micro-sized planetary roller ball screw pairs.

[0006] To solve the above technical problems, the present invention provides the following technical solution: a vertical micro-miniature planetary roller screw pair stroke error test bench, including a vertical bed and a guide rail mounted on the vertical bed, a headstock connecting the bed is provided on the top of the vertical bed, a pneumatic chuck is provided on the headstock connecting the bed, and a circular grating is coaxially mounted on the spindle of the pneumatic chuck, the circular grating being used to measure theoretical angular displacement;

[0007] A tailstock is mounted on the guide rail. The pneumatic chuck and tailstock are used to perform double-end suspension clamping and positioning of the non-threaded round end face of the tested lead screw pair. A positioning bearing platform is slidably arranged on the guide rail. A micro-motion measuring platform is arranged on the upper part of the positioning bearing platform. Tooling is configured on the micro-motion measuring platform. An air float and a constant force spring are configured between the micro-motion measuring platform and the positioning bearing platform.

[0008] The vertical bed is equipped with a laser mounting base at its bottom, and a laser interference ruler is mounted on the laser mounting base. The laser interference ruler is used in conjunction with the reflector on the micro-motion measuring platform to measure the actual travel of the micro-motion measuring platform along the lead screw axis.

[0009] As a preferred embodiment of the vertical micro-miniature planetary roller screw pair stroke error test bench of the present invention, wherein: the sliding direction of the positioning bearing platform is parallel to the axial direction of the screw pair being tested.

[0010] As a preferred embodiment of the vertical micro-miniature planetary roller screw pair stroke error test bench of the present invention, the constant force spring is used to output a constant force that is equal in magnitude and opposite in direction to the total weight of the micro-motion measurement platform and the tooling.

[0011] As a preferred embodiment of the vertical micro-miniature planetary roller screw pair stroke error test bench of the present invention, the constant force spring is a magnetic compensation mechanism, including opposing magnetic pole components, which outputs a constant magnetic thrust by adjusting the air gap of the magnetic poles, thereby offsetting the vertical self-weight without mechanical contact.

[0012] As a preferred embodiment of the vertical micro-miniature planetary roller screw pair stroke error test bench of the present invention, the air float is used to counteract the frictional force during the operation of the micro-motion measurement platform.

[0013] As a preferred embodiment of the vertical micro-miniature planetary roller screw pair stroke error test bench of the present invention, it further includes a first servo motor, which is connected to the spindle end of the pneumatic chuck via a coupling to provide rotational driving force for the screw pair under test.

[0014] As a preferred embodiment of the vertical micro-miniature planetary roller screw pair stroke error test bench of the present invention, it further includes a second servo motor and a third servo motor.

[0015] The second servo motor is connected to the first transmission screw and is used to drive the positioning bearing platform to move macroscopically along the guide rail;

[0016] The third servo motor is connected to the second transmission screw and is used to drive the tailstock to move up and down along the guide rail to adaptively clamp the test screw pairs of different lengths.

[0017] As a preferred embodiment of the vertical micro-miniature planetary roller screw pair stroke error test bench of the present invention, the laser interference scale is symmetrically arranged along the axis of the screw pair under test, and the Abbe error is eliminated by adopting a dual-optical-path symmetrical measurement mechanism.

[0018] As a preferred embodiment of the vertical micro-miniature planetary roller screw pair stroke error test bench of the present invention, wherein: the tooling on the micro-motion measurement platform includes a measuring frame tooling and a V-block tooling;

[0019] When performing the comprehensive stroke error test of the tested lead screw pair, a V-block fixture is used to establish the connection between the micro-motion measurement platform and the nut of the tested lead screw pair.

[0020] When testing the stroke error of components such as the outer raceway or rollers of a single lead screw shaft, a measuring fixture is used, with the probe of the measuring fixture directly attached to the raceway of the part being tested.

[0021] As a preferred embodiment of the vertical micro-miniature planetary roller screw pair stroke error test bench of the present invention, it further includes a host computer control system, which is electrically connected to a circular grating and a laser interference ruler respectively, for synchronously extracting theoretical angular displacement and actual linear stroke under a unified clock reference, and performing spatiotemporal alignment and subtraction on the two signals to calculate and generate the full stroke error of the tested screw pair.

[0022] The beneficial effects of the present invention are as follows: (1) The vertical micro-sized planetary roller screw pair stroke error test bench of the present invention uses a pneumatic clamping device and a tailstock to clamp the non-threaded round end face of the screw pair under test, which solves the problem that traditional double centers are difficult to process the center hole and position on the small-sized end face; (2) The present invention adopts a vertical structure and uses the gravity of the follower component and the screw pair under test as the axial preload to eliminate the test gap, avoiding the problem of preload force gathering on one side of the transmission surface and uneven force caused by the traditional horizontal mechanical forced preload, and truly reflects the micro-sized screw pair's micro-force state; (3) The present invention uses a double-layer measurement structure with an air float block mounted on a positioning bearing platform to separate the positioning and following function of the positioning bearing platform from the precise movement function of the air float block, eliminating the mechanical interference caused by long stroke movement and ensuring the accuracy of stroke error measurement; (4) The present invention is equipped with an air float block and a constant force spring, which offsets the friction force and vertical self-weight of the micro-motion platform during operation, eliminates external mechanical disturbances, and further improves the accuracy of micron-level stroke error testing. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure in an embodiment of the present invention.

[0024] Figure 2 This is a side view of the overall structure in an embodiment of the present invention.

[0025] Figure 3 This is a front view of the overall structure in an embodiment of the present invention.

[0026] Figure 4 This is a schematic diagram of the micro-motion measurement platform and the positioning support platform in an embodiment of the present invention.

[0027] Reference numerals in the attached drawings: 1. First servo motor; 2. Headstock connecting bed; 3. Pneumatic chuck; 4. Constant force spring; 5. Test lead screw pair; 6. Micro-motion measuring platform; 7. Positioning bearing platform; 8. Air float; 9. Tailstock; 10. Second servo motor; 11. Laser interference ruler; 12. Coupling; 13. Circular grating; 14. First transmission lead screw; 15. Measuring frame fixture; 16. V-block fixture; 17. Second transmission lead screw; 18. Guide rail; 19. Laser mounting base; 20. Vertical bed; 21. Third servo motor. Detailed Implementation

[0028] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0029] The test bench provided in this embodiment is typically deployed in a precision measurement laboratory environment with constant temperature and humidity. It needs to be equipped with an air source for the use of the air flotation blocks and needs to be connected to a stable industrial power supply and a host computer control system.

[0030] Example 1, referring to Figures 1 to 4 This embodiment provides a vertical micro-miniature planetary roller screw pair stroke error test bench, including a vertical bed 20 and a guide rail 18 installed on the vertical bed 20. A headstock connecting the bed 2 is provided on the top of the vertical bed 20. A pneumatic chuck 3 is provided on the headstock connecting the bed 2. A circular grating 13 is coaxially installed on the spindle of the pneumatic chuck 3. The circular grating 13 is used to measure the theoretical angular displacement.

[0031] A tailstock 9 is mounted on the guide rail 18. The pneumatic chuck 3 and the tailstock 9 are used to perform double-end suspension clamping and positioning of the non-threaded round end face of the lead screw pair 5 under test. The guide rail 18 can slide to position the bearing platform 7, and a micro-motion measuring platform 6 is provided on the upper part of the positioning bearing platform 7. The micro-motion measuring platform 6 is equipped with a tooling and is used to extract the actual displacement of the lead screw pair 5 under test. An air float 8 and a constant force spring 4 are arranged between the micro-motion measuring platform 6 and the positioning bearing platform 7. In this invention, the micro-motion measuring platform 6 is connected to the lead screw pair 5 under test through the tooling, and its actual displacement directly reflects the stroke error of the lead screw pair 5 under test, so that the micro-motion measuring platform 6 is in a suspended state to eliminate external interference.

[0032] A laser mounting base 19 is installed at the bottom of the vertical bed 20. A laser interference ruler 11 is installed on the laser mounting base 19. The laser interference ruler 11 is used to cooperate with the reflector on the micro-motion measuring platform 6 to measure the actual travel of the micro-motion measuring platform 6 along the lead screw axis.

[0033] In this invention, the vertical bed 20 serves as the main load-bearing structure, installed and fixed on the ground or vibration isolation platform. It provides stable support for the headstock connecting the bed 2, tailstock 9, and micro-motion measurement platform 6, and ensures the vertical movement accuracy of each component. The guide rail 18 is fixedly installed on the vertical bed 20 along the vertical direction to guide the tailstock 9 and the positioning load-bearing platform 7 to perform linear movements.

[0034] This invention employs a vertical layout, with the tested lead screw assembly 5 suspended and clamped at both ends by a pneumatic chuck 3 and a tailstock 9. This clamping method utilizes the pneumatic chuck 3 to hold the non-threaded circular end face, replacing the reliance on a center hole in traditional double-center clamping systems, thus solving the problems of small end faces, difficulty in drilling, and easy deformation in micro-sized lead screw assemblies. Simultaneously, in the vertical orientation, the gravity direction of the tested lead screw assembly 5 and its follower components (such as the micro-motion measurement platform 6) is aligned with the lead screw axis, naturally forming a uniform axial preload. This gravity preload method eliminates the uneven force distribution problem caused by mechanical forced preload in traditional horizontal devices, avoids measurement errors introduced by unilateral preload concentration, and truly reflects the microscopic force state of the micro-sized lead screw assembly.

[0035] Furthermore, the positioning support platform 7 is responsible for long-stroke macroscopic tracking, eliminating the interference of long-stroke motion on measurement accuracy; the micro-motion measurement platform 6, supported by the air float 8 and the constant force spring 4, is in a floating state with minimal friction and gravity influence, enabling it to extremely sensitively capture the micron-level stroke error of the tested lead screw pair 5. This structural design eliminates external mechanical disturbances and significantly improves testing accuracy.

[0036] The sliding direction of the positioning bearing platform 7 is parallel to the axial direction of the lead screw pair 5 being measured.

[0037] The constant force spring 4 is used to output a constant force that is equal in magnitude and opposite in direction to the total weight of the micro-motion measuring platform 6 and the tooling. The constant force spring 4 is a magnetic compensation mechanism, which includes opposing magnetic pole components. By adjusting the air gap between the magnetic poles, it outputs a constant magnetic thrust, thus counteracting the vertical self-weight without mechanical contact.

[0038] The air flotation block 8 is used to counteract the frictional force when the micro-motion measurement platform 6 is running.

[0039] The test bench also includes a first servo motor 1, which is connected to the spindle end of the pneumatic chuck 3 via a coupling 12 to provide rotational driving force for the tested lead screw pair 5.

[0040] The test bench also includes a second servo motor 10 and a third servo motor 21; wherein the second servo motor 10 is connected to the first transmission screw 14 and is used to drive the positioning bearing platform 7 to move macroscopically along the guide rail 18; the third servo motor 21 is connected to the second transmission screw 17 and is used to drive the tailstock 9 to move up and down along the guide rail 18 so as to adaptively clamp the test screw pair 5 of different lengths.

[0041] The laser interference ruler 11 is symmetrically arranged along the axis of the lead screw pair 5 being measured, and the Abbe error is eliminated by adopting a dual-optical-path symmetrical measurement mechanism.

[0042] The tooling on the micro-motion measurement platform 6 includes a measuring frame tooling 15 and a V-block tooling 16. When performing a comprehensive stroke error test on the lead screw pair 5, the V-block tooling 16 is used to establish a connection between the micro-motion measurement platform 6 and the nut of the lead screw pair 5. When performing a stroke error test on components such as the outer raceway or roller of a single lead screw shaft, the measuring frame tooling 15 is used, and the probe of the measuring frame tooling 15 is directly attached to the raceway of the part being measured.

[0043] The test bench also includes a host computer control system, which is electrically connected to the circular grating 13 and the laser interference ruler 11 respectively. It is used to synchronously extract the theoretical angular displacement and the actual linear travel under a unified clock reference, and to perform spatiotemporal alignment and subtraction on the two signals to calculate and generate the full travel error of the tested lead screw pair 5.

[0044] Before testing, the test bench of this invention first drives the third servo motor 21 connected to the second transmission screw 17, adjusts the tailstock 9 to a suitable height, and installs the screw pair 5 under test between the pneumatic chuck 3 and the tailstock 9. In a vertical position, the gravity of the follower component and the gravity of the screw pair 5 under test are used as a uniform axial preload to eliminate the test gap in the measurement direction.

[0045] After the tested lead screw pair 5 is fixed, the measuring device can be started to measure the stroke error of the planetary roller lead screw pair or rollers. During the test, the first servo motor 1 drives the tested lead screw pair 5 to rotate, and the circular grating 13 records the theoretical angular displacement; at the same time, the second servo motor 10 connected to the first transmission lead screw 14 drives the positioning bearing platform 7 to perform macroscopic coarse following, and the micro-motion measuring platform 6 is in a floating state supported by the air float 8 and the constant force spring 4, and its actual linear displacement is extracted synchronously by the laser interference ruler 11. The system can calculate the full stroke error of the tested lead screw pair 5 by performing spatiotemporal alignment and subtraction of the two signals.

[0046] Example 2, refer to Figures 1 to 3 This embodiment is based on the previous embodiment, but differs in that it provides a method for using a vertical miniature planetary roller screw pair stroke error test bench. The method includes the following steps.

[0047] S1, Clamping and pre-tightening of the tested lead screw pair 5: Based on the length of the tested lead screw pair 5, control the third servo motor 21 to drive the second transmission lead screw 17, and adjust the position of the tailstock 9 on the guide rail 18 to a suitable height. The upper non-threaded round end face of the tested lead screw pair 5 is inserted into the pneumatic chuck 3 of the headstock and clamped, while the lower end is supported on the tailstock 9. In a vertical position, the servo component (micro-motion measurement platform 6 and tooling) and the gravity of the tested lead screw pair 5 itself serve as a uniform axial pre-tightening force to eliminate test gaps in the measurement direction.

[0048] S2, Drive and Theoretical Data Acquisition: Start the first servo motor 1, which drives the tested lead screw pair 5 to rotate through the coupling 12 and pneumatic chuck 3. At the same time, the circular grating 13, which is coaxially mounted with the main shaft, collects the angle signal of the tested lead screw pair 5 in real time, transmits it to the host computer control system, and converts it into theoretical linear stroke.

[0049] S3, Following and Actual Data Acquisition: The second servo motor 10 drives the first transmission screw 14, causing the positioning support platform 7 to macroscopically follow the movement along the guide rail 18, maintaining its approximate relative position with the nut or moving part of the measured screw pair 5. The micro-motion measurement platform 6 is in a floating state supported by the air float 8 (to counteract friction) and the constant force spring 4 (to counteract its own weight), accurately capturing the actual displacement of the measured screw pair 5 through the fixture (V-block fixture 16 or measuring frame fixture 15). The laser interferometer 11 synchronously acquires the actual linear displacement signal of the micro-motion measurement platform 6.

[0050] S4, Error Calculation: Under a unified clock reference, the host computer control system performs spatiotemporal alignment between the theoretical angular displacement acquired by the circular grating 13 and the actual linear travel acquired by the laser interferometer 11. Based on the theoretical angular displacement, the theoretical linear travel is calculated, and the difference between the actual linear displacement and the theoretical linear travel is calculated to generate the full-stroke error curve of the measured lead screw pair 5.

[0051] In specific implementation, in step S3, the macroscopic following motion of the positioning support platform 7 and the micro-motion measurement process of the micro-motion measurement platform 6 are decoupled. The servo following strategy of the positioning support platform 7 only needs to ensure that the micro-motion measurement platform 6 does not exceed its effective stroke range, without requiring extremely high positioning accuracy, thus reducing the accuracy requirements for the long-stroke drive system. Meanwhile, the micro-motion measurement platform 6 focuses on high-precision displacement transmission. The air float 8 significantly eliminates the frictional resistance of the guide rail, and the constant force spring 4 eliminates the influence of vertical gravity on the measured force, enabling the micro-motion measurement platform 6 to follow the measured lead screw pair 5 with minimal resistance, ensuring the authenticity and high accuracy of the measurement data.

Claims

1. A vertical miniature planetary roller screw pair stroke error test bench, characterized in that, It includes a vertical bed (20) and a guide rail (18) installed on the vertical bed (20). A head frame connecting bed (2) is provided on the top of the vertical bed (20). A pneumatic chuck (3) is provided on the head frame connecting bed (2). A circular grating (13) is coaxially installed on the spindle of the pneumatic chuck (3). The circular grating (13) is used to measure theoretical angular displacement. A tailstock (9) is installed on the guide rail (18). The pneumatic chuck (3) and the tailstock (9) are used to perform double-end suspension clamping and positioning of the non-threaded round end face of the screw pair (5) under test. A positioning bearing platform (7) is slidably set on the guide rail (18). A micro-motion measuring platform (6) is set on the upper part of the positioning bearing platform (7). A tooling is configured on the micro-motion measuring platform (6). An air float (8) and a constant force spring (4) are configured between the micro-motion measuring platform (6) and the positioning bearing platform (7). The vertical bed (20) is equipped with a laser mounting base (19) at the bottom, and a laser interference ruler (11) is installed on the laser mounting base (19). The laser interference ruler (11) is used to cooperate with the reflector on the micro-motion measurement platform (6) to measure the actual travel of the micro-motion measurement platform (6) along the lead screw axis.

2. The vertical miniature planetary roller screw pair stroke error test bench as described in claim 1, characterized in that: The sliding direction of the positioning bearing platform (7) is parallel to the axial direction of the lead screw pair (5) being measured.

3. The vertical miniature planetary roller screw pair stroke error test bench as described in claim 1, characterized in that: The constant force spring (4) is used to output a constant force that is equal in magnitude and opposite in direction to the total weight of the micro-motion measuring platform (6) and the tooling.

4. The vertical miniature planetary roller screw pair stroke error test bench as described in claim 3, characterized in that: The constant force spring (4) is a magnetic compensation mechanism, which includes magnetic pole components arranged opposite to each other. By adjusting the air gap between the magnetic poles, it outputs a constant magnetic thrust to counteract the vertical self-weight without mechanical contact.

5. The vertical miniature planetary roller screw pair stroke error test bench as described in claim 1, characterized in that: The air flotation block (8) is used to counteract the frictional force during the operation of the micro-motion measurement platform (6).

6. The vertical miniature planetary roller screw pair stroke error test bench as described in claim 1, characterized in that: It also includes a first servo motor (1), which is connected to the spindle end of the pneumatic chuck (3) via a coupling (12) to provide rotational driving force for the test lead screw pair (5).

7. The vertical miniature planetary roller screw pair stroke error test bench as described in claim 1, characterized in that: It also includes a second servo motor (10) and a third servo motor (21). The second servo motor (10) is connected to the first transmission screw (14) and is used to drive the positioning bearing platform (7) to move along the guide rail (18); The third servo motor (21) is connected to the second transmission screw (17) to drive the tailstock (9) to move up and down along the guide rail (18) so as to adaptively clamp the test screw pair (5) of different lengths.

8. The vertical miniature planetary roller screw pair stroke error test bench as described in claim 1, characterized in that: The laser interference ruler (11) is symmetrically arranged along the axis of the lead screw pair (5) being measured, and the Abbe error is eliminated by adopting a dual-optical-path symmetrical measurement mechanism.

9. The vertical miniature planetary roller screw pair stroke error test bench as described in claim 1, characterized in that: The tooling on the micro-motion measurement platform (6) includes a measurement frame tooling (15) and a V-block tooling (16). When performing a comprehensive stroke error test on the lead screw pair (5), a V-block fixture (16) is used to establish a connection between the micro-motion measurement platform (6) and the nut of the lead screw pair (5). When testing the stroke error of components such as the outer raceway or roller of a single lead screw shaft, a measuring fixture (15) is used, and the probe of the measuring fixture (15) is directly attached to the raceway of the part being tested.

10. The vertical miniature planetary roller screw pair stroke error test bench as described in claim 1, characterized in that: It also includes a host computer control system, which is electrically connected to the circular grating (13) and the laser interference scale (11) respectively. It is used to synchronously extract the theoretical angular displacement and the actual linear travel under a unified clock reference, and to perform spatiotemporal alignment and subtraction on the two signals to calculate the full travel error of the measured lead screw pair (5).

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