System and method for measuring dynamic friction coefficient of rolling linear guide rail pair

Abstract

The invention discloses a system for measuring the dynamic friction coefficient of a rolling linear guide rail pair. The system comprises a marble lathe bed, a driving module, a measuring module, a supporting module and a load adjusting module, the driving module drives the measuring module to reciprocate through the lead screw; the measuring module is provided with a tension and pressure sensor for collecting the pre-tightening force required for dragging the measured guide rail in real time; the load module applies an adjustable vertical load by adopting a pair of precise flat tongs and an opposite top type sliding block, and the load is monitored by a pressure sensor; during measurement, one end of the guide rail is clamped and arranged on the plane needle bearing through the connecting block, the other end of the guide rail is embedded into the opposite-vertex sliding block, and the supporting module adjusts the height to make the guide rail horizontal; the system calculates a dynamic friction coefficient based on a Hertz contact theory and a slide block skirt elastic deformation model in combination with actually measured dragging force and load data; the device has the advantages of being non-destructive, accurate in load, wide in applicable model, high in measurement precision and the like, and is suitable for dynamic friction performance testing of the rolling linear guide rail pair.

Description

Technical Field

[0001] This invention relates to the field of mechanical testing and measurement technology, and in particular to a system and method for measuring the dynamic friction coefficient of a rolling linear guide pair. Background Technology

[0002] As a core functional component of precision transmission and positioning systems, the dynamic friction coefficient of rolling linear guide pairs is a key performance indicator for evaluating the smoothness of guide rail operation, positioning accuracy, energy efficiency, and service life. Accurate measurement of the dynamic friction coefficient is of great significance for guide pair design optimization, process improvement, condition monitoring, and overall system performance enhancement.

[0003] Currently, common methods for measuring the friction coefficient of rolling linear guide pairs are mainly divided into two categories: indirect estimation methods and direct measurement methods. Indirect estimation methods typically infer friction characteristics by measuring the current, torque, or system vibration signals of the drive motor. This method is susceptible to interference from transmission chain clearance, inertial coupling, and electrical noise, resulting in low accuracy and poor repeatability. Direct measurement methods often employ a split-slider test structure, requiring the slider to be cut or modified before testing to install a force sensor. While this method can directly acquire force signals, it disrupts the overall structure and preload of the slider, leading to significant differences between the test conditions and actual operating conditions. Therefore, it cannot accurately reflect the friction behavior of the complete guide pair under sealed, lubricated, and preloaded conditions.

[0004] Furthermore, existing testing devices often employ weight stacking or simple mechanical pressurization for load simulation, which suffers from problems such as sudden load jumps, large force fluctuations, and difficulty in precise adjustment and maintenance, making it difficult to achieve continuous and stable load application during uniform motion. Simultaneously, most testing fixtures are designed for specific guide rail models, lacking versatility, and adjustments are cumbersome when changing the test component. Moreover, they lack analysis and modeling of microscopic contact characteristics such as elastic deformation of the slider skirt and changes in contact angle, resulting in significant deviations in contact load calculations and ultimately affecting the accuracy of friction coefficient measurements. Summary of the Invention

[0005] This invention overcomes the shortcomings of the prior art and provides a system and method for measuring the dynamic friction coefficient of a rolling linear guide pair.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a dynamic friction coefficient measurement system and method for rolling linear guide pairs, comprising: a support frame, a marble bed, a test piece, and a drive module, a measurement module, a support module, and a load adjustment module installed on the marble bed;

[0007] The drive module includes a mounting base, a drive motor, and a lead screw connected to the output end of the drive motor. The lead screw passes through the measurement module and the support module in sequence.

[0008] The measuring module is slidably connected to the marble bed and threadedly connected to the lead screw; the measuring module includes a main worktable, a fixed table, and a tension / compression sensor mounting base plate; the tension / compression sensor mounting base plate is equipped with a tension / compression sensor, an S-shaped sensor connecting block, a guide rail connecting block, and a single-row flat needle roller bearing located below the guide rail connecting block;

[0009] The support module includes at least two sets of lifting components and a set of lead screw tailstock. The top of the lifting components abuts against the bottom of the test piece, and the lead screw tailstock is used to support the end of the lead screw.

[0010] The load adjustment module includes a base plate, a flat-jaw pliers mounting plate, a pressure sensor, a force block, a counter-rotating slider, and a slider fixing component; the counter-rotating slider is used to clamp the test piece, and ball bearings are provided at the four corners of the inner wall to adjust the applied pressure.

[0011] In a preferred embodiment of the present invention, a threaded sleeve that mates with the lead screw is provided at the fixed platform, the tension / compression sensor, the S-shaped sensor connecting block and the guide rail connecting block are connected in sequence, and a U-shaped measuring platform is provided at the end of the guide rail connecting block. At least one set of the planar single-row needle roller bearing is provided and is located below the measuring platform. A guide rail is provided on the marble bed, and a connector that mates with the guide rail is provided at the bottom of the measuring module.

[0012] In a preferred embodiment of the present invention, at least two sets of the lifting components are of the same size. One set of the lifting components includes a base fixed to the marble bed, a support frame guide plate, a roller bracket, and a support roller. The support frame guide plate has a through hole through which the lead screw can pass. Mounting plates are provided at both ends of one side of the roller bracket, and support rollers for supporting the test piece are installed on opposite sides of the two mounting plates.

[0013] In a preferred embodiment of the present invention, a precision flat-jaw pliers is fixed above the mounting plate of the flat-jaw pliers. The pressure sensor, force block, top-mounted slider and slider fixing component are all mounted above the precision flat-jaw pliers. A fine-tuning fixing plate that can adjust the lateral displacement of the precision flat-jaw pliers is provided on one side of the mounting plate of the flat-jaw pliers.

[0014] In a preferred embodiment of the present invention, the load adjustment module has at least one set of the lifting components on both sides, and the lead screw tailstock is located between the load adjustment module and one of the sets of lifting components.

[0015] In a preferred embodiment of the present invention, the roller bracket and the support frame guide plate are connected by a telescopic rod.

[0016] In a preferred embodiment of the present invention, a method for measuring the dynamic friction coefficient of a rolling linear guide pair is provided, applied to the aforementioned dynamic friction coefficient measurement system for a rolling linear guide pair, comprising the following steps:

[0017] S1. Install the measuring module, support module, load adjustment module, and lead screw tailstock onto the marble bed in sequence.

[0018] S2. Install the drive motor on the mounting base, and let the lead screw pass through the measuring module and the support module in sequence. Connect one end to the output end of the drive motor and the other end to the lead screw tailstock.

[0019] S3. Place the workpiece under test. One end of the workpiece is placed naturally on the single-row needle roller bearing on the measuring platform. The other end is placed between the opposing sliders with the bottom of the opposing slider as the reference. Adjust the height of the support module so that the workpiece under test is parallel to the marble bed.

[0020] S4. The running program is set by the drive controller, the drive motor drives the lead screw shaft to rotate, the lead screw drives the entire measuring module to move back and forth, and the tension and compression sensors record the real-time data of the pre-tightening drag force, and then calculate the dynamic friction coefficient of the measured part.

[0021] In a preferred embodiment of the present invention, the method for calculating the dynamic friction coefficient includes:

[0022] S401. Obtain the structural parameters, material parameters, and initial preload of the rolling linear guide pair;

[0023] S402. Based on Hertzian contact theory, calculate the initial contact deformation between the ball and the workpiece, and between the ball and the opposing slider, under the initial preload.

[0024] S403. Based on the force balance, deformation coordination relationship and geometric relationship of the top-mounted slider under vertical load, establish a contact load calculation model that includes the influence of elastic deformation of the top-mounted slider skirt; wherein, the deformation of the top-mounted slider skirt is equivalent to the deformation of a cantilever beam fixed at one end at the contact point.

[0025] S404. Substitute the vertical load into the contact load calculation model to solve for the actual contact load between each ball and the test piece.

[0026] S405. Calculate the dynamic friction coefficient based on the measured pre-tightening drag force and the calculated actual contact load.

[0027] In a preferred embodiment of the present invention, the method for calculating the dynamic friction coefficient further includes:

[0028] S411. Based on the force balance of the opposing slider in the horizontal direction, and based on the geometric position changes of the opposing slider and the curvature center of the measured part before and after bearing the measured part, establish the relationship between the contact angle change and the vertical displacement of the opposing slider, the skirt deformation, and the contact deformation.

[0029] S412. Express the deformation of the top-mounted slider skirt as a function of the contact load at the corresponding position; establish the relationship between the vertical displacement, the total contact deformation, and the initial deformation based on the deformation compatibility conditions; combine the above relationships to construct a set of equations for solving the actual contact load.

[0030] In a preferred embodiment of the present invention, calculating the initial contact deformation based on the Hertzian contact theory includes:

[0031] Based on the initial preload, ball diameter, radius of curvature of the test piece, material elastic modulus and Poisson's ratio, calculate the Hertzian contact load-deformation coefficient between the ball and the test piece, and between the ball and the opposing slider.

[0032] The initial contact deformation is calculated using the load-deformation coefficient and the initial preload.

[0033] This invention addresses the shortcomings of the prior art and has the following beneficial effects:

[0034] (1) The top-mounted guide rail clamping method is adopted, which does not require disassembly or damage to the original structure of the slider. The dynamic friction coefficient of the rolling linear guide pair can be measured under simulated real motion conditions, and the test process is closer to the actual working conditions.

[0035] (2) The system adopts a marble bed and precision screw drive, which has good structural rigidity and smooth movement; the tension and pressure sensors collect the drag force data in real time, and combined with the load analysis algorithm based on Hertz contact theory and the elastic deformation model of the slider skirt, the contact load and friction coefficient can be accurately calculated, and the results are reliable and highly repeatable.

[0036] (3) The load is accurately applied and monitored by precision flat jaw pliers and pressure sensor. The load size is adjustable and the fluctuation is small. The support module is equipped with a liftable roller structure, which can adapt to the height difference of different models of guide rails. The clamping and adjustment are convenient and the system has strong versatility.

[0037] (4) The measurement module uses a single-row flat needle roller bearing to support one end of the guide rail being measured, reducing friction interference; the top slider is equipped with ball self-adjustment pressure adjustment to ensure uniform load distribution and effectively avoid measurement errors caused by slider inertia.

[0038] (5) By replacing the guide rail connecting block and adjusting the lateral position and support height of the flat jaw clamp, the system can quickly adapt to linear guide rail pairs of different specifications, has good expandability, and is suitable for various scenarios such as R&D, quality inspection and performance evaluation. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a front view of the dynamic friction coefficient measurement system for a rolling linear guide pair according to a preferred embodiment of the present invention;

[0041] Figure 2 This is a schematic diagram of the overall structure of the dynamic friction coefficient measurement system for a rolling linear guide pair according to a preferred embodiment of the present invention;

[0042] Figure 3 This is a schematic diagram of the measurement module structure of the dynamic friction coefficient measurement system for a rolling linear guide pair according to a preferred embodiment of the present invention;

[0043] Figure 4 This is a schematic diagram of the support module structure of the dynamic friction coefficient measurement system for a rolling linear guide pair according to a preferred embodiment of the present invention;

[0044] Figure 5 This is a schematic diagram of the load adjustment module structure of the dynamic friction coefficient measurement system for rolling linear guide pairs according to a preferred embodiment of the present invention.

[0045] Figure 6 This is a schematic diagram of the mechanical model analysis of the top structure under no-load condition of the dynamic friction coefficient measurement system for the rolling linear guide pair according to a preferred embodiment of the present invention;

[0046] Figure 7 This is a schematic diagram of the mechanical model analysis of the top structure under loading conditions of the dynamic friction coefficient measurement system for rolling linear guide pairs according to a preferred embodiment of the present invention;

[0047] Figure 8 This is a schematic diagram of the top structure sliders 3 and 4 raceways under loading conditions of the dynamic friction coefficient measurement system for the rolling linear guide pair according to a preferred embodiment of the present invention.

[0048] In the picture: 1. Support frame; 2. Marble bed frame;

[0049] 3. Drive module; 3.1 Mounting base; 3.2 Drive motor; 3.3 Lead screw;

[0050] 4. Measurement module; 4.1 Main worktable; 4.2 Fixed platform; 4.3 Tension / compression sensor mounting base plate; 4.4 Tension / compression sensor; 4.5 S-type sensor connecting block; 4.6 Guide rail connecting block; 4.7 Measurement platform; 4.8 Flat single-row needle roller bearing; 4.9 Connector;

[0051] 5. Support module; 5.1 Base; 5.2 Support frame guide plate; 5.3 Roller bracket; 5.4 Mounting plate; 5.5 Support rollers;

[0052] 6. Load adjustment module; 6.1 Base plate; 6.2 Flat-jaw pliers mounting plate; 6.3 Pressure sensor; 6.4 Force block; 6.5 Top-mounted slider; 6.6 Slider fixing component;

[0053] 8. Test piece; 9. Lead screw tailstock. Detailed Implementation

[0054] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0056] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the scope of protection of this application. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0057] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art will understand the specific meaning of the above terms in this application based on the specific circumstances.

[0058] like Figures 1-2 As shown, a dynamic friction coefficient measurement system for a rolling linear guide pair includes: a support frame 1, a marble bed 2, a test piece 8, and a drive module 3, a measurement module 4, a support module 5, and a load adjustment module 6 installed on the marble bed 2.

[0059] The drive module 3 is used to drive the measuring module 4 to reciprocate along the length of the marble bed 2. Specifically, it includes: a mounting base 3.1, a drive motor 3.2, and a lead screw 3.3 connected to the output end of the drive motor 3.2. The lead screw 3.3 passes through the measuring module 4 and the support module 5 in sequence.

[0060] like Figure 3 As shown, the measurement module 4 is used to measure the preload drag force of the test piece 8 during reciprocating motion, which is used for subsequent dynamic friction coefficient calculation. Specifically, the measurement module 4 is slidably connected to the marble bed 2 and threadedly connected to the lead screw 3.3; the measurement module includes a main worktable 4.1, a fixed table 4.2, and a tension / compression sensor mounting base plate 4.3; the tension / compression sensor mounting base plate 4.3 is equipped with a tension / compression sensor 4.4, an S-shaped sensor connecting block 4.5, a guide rail connecting block 4.6, and a single-row flat needle roller bearing 4.8 located below the guide rail connecting block 4.6.

[0061] Here, the test piece 8 uses a two-rail-opposite configuration. Each type of rail has a corresponding connecting block for clamping, allowing it to be naturally placed into the S-shaped sensor connecting block. The test piece 8 should be installed in a straight line with the transmission screw 3.3 to avoid uneven loading. Since the slider dimensions for the same type of rail are inconsistent, only the thickness of the test fixture needs to be adjusted. The tension / compression sensor can read the preload drag force in real time for subsequent dynamic friction coefficient calculation. The opposing rails are tightly connected to the slotted nut using hexagonal bolts. When testing other types of rails, only the tension / compression sensor mounting base needs to be replaced, ensuring high versatility and interchangeability.

[0062] The fixed platform 4.2 is provided with a threaded sleeve that mates with the lead screw 3.3. The tension and compression sensor 4.4, the S-shaped sensor connecting block 4.5, and the guide rail connecting block 4.6 are connected in sequence, and the end of the guide rail connecting block 4.6 is provided with a U-shaped measuring platform 4.7. At least one set of the planar single-row needle roller bearing 4.8 is provided and is located below the measuring platform 4.7. The marble bed 2 is provided with a guide rail, and the bottom of the measuring module 4 is provided with a connector 4.9 that mates with the guide rail.

[0063] In one embodiment, the marble bed 2 further includes a pair of parallel main guide rails arranged along the length of the marble bed 2 body, with the main worktable 4.1 located on the joint 4.9 of the main guide rails. The marble bed 2 is also provided with grooves parallel to the main guide rails, and cable chains are installed in the grooves for placing various cables of the system.

[0064] Preferably, in one embodiment, the drive module 3 includes a drive motor 3.2, a lead screw 3.3, and a lead screw nut; the drive motor 3.2 is mounted on a mounting base 3.1 fixed on the marble bed 2 body and located between the pair of parallel main guide rails; the lead screw nut is mounted on a threaded sleeve mounting block fixed on the main worktable 4.1; the drive motor 3.2 drives the lead screw 3.3 to rotate via a coupling, which in turn drives the lead screw nut to move and thus drives the main worktable 4.1 to reciprocate axially along the direction of the main guide rails; the lead screw 3.3 passes through a support module 5 on the marble bed 2 body.

[0065] Here, the speed of the work platform can be indirectly controlled by controlling the rotational speed of the drive motor 3.2. The rated speed of the drive motor 3.2 is 3000 rpm, and the lead of the lead screw 3.3 is 20 mm. The speed of the worktable is adjusted by controlling the rotational speed of the drive motor 3.2. Furthermore, the drive motor 3.2 has advantages such as low load force fluctuation, stable control, and high loading accuracy.

[0066] Preferably, in some embodiments, the outer helical raceway of the ball screw 3.3 contains a plurality of circulating raceways, the center of the ball return channels of the plurality of circulating raceways is on the same helical line, and the ball return channels on the circulating raceways are evenly distributed in the circumferential direction of the ball screw.

[0067] like Figure 4 As shown, the support module 5 includes at least two sets of lifting components and a set of lead screw tailstock 9. The top of the lifting components abuts against the bottom of the test piece 8, and the lead screw tailstock 9 is used to support the end of the lead screw 3.3.

[0068] At least two sets of the lifting components are completely identical in size. One set of the lifting components includes a base 5.1 fixed on the marble bed 2, a support frame guide plate 5.2, a roller bracket 5.3, and a support roller 5.5. The support frame guide plate 5.2 has a through hole through which the lead screw 3.3 can pass. Both ends of one side of the roller bracket 5.3 are provided with mounting plates 5.4, and the opposite sides of the two mounting plates 5.4 are equipped with support rollers 5.5 for supporting the test piece 8.

[0069] The roller bracket 5.3 and the support frame guide plate 5.2 are connected by a telescopic rod. Because the height of different models of guide rails is different, a precision flat-jaw pliers is used as a reference. Here, the lifting device can both lift and support, and the upper end of the lifting device adopts a roller structure, which can greatly reduce system errors.

[0070] like Figure 5 The load adjustment module 6 includes a base plate 6.1, a flat-jaw pliers mounting plate 6.2, a pressure sensor 6.3, a force-bearing block 6.4, a counter-rotating slider 6.5, and a slider fixing component 6.6; the counter-rotating slider 6.5 is used to clamp the test piece 8, and ball bearings are provided at the four corners of its inner wall to adjust the applied pressure.

[0071] A precision flat-jaw pliers is fixed above the mounting plate 6.2 of the flat-jaw pliers. The pressure sensor 6.3, the force block 6.4, the top-mounted slider 6.5, and the slider fixing part 6.6 are all installed above the precision flat-jaw pliers. A fine-tuning fixing plate that can adjust the lateral displacement of the precision flat-jaw pliers is provided on one side of the mounting plate 6.2 of the flat-jaw pliers.

[0072] Furthermore, a precision flat-jaw vise is used to simulate different load conditions of a linear guide. This precision flat-jaw vise, through a helical force-multiplying mechanism, can generate a large clamping force with minimal input force, providing reliable self-locking, good clamping rigidity, and precise and stable workpiece positioning. To prevent the top-mounted slider 6.5 from moving along the guide direction, a slider fixing component is fixed in the vise jaw direction to secure the slider. The magnitude of the load force on the precision flat-jaw vise can be read in real time by a pressure sensor, enabling precise load control.

[0073] The precision flat-jaw vises are fixed to the mounting plate by the vise clamping plate. If testing other types of guide rails is required, the precision flat-jaw vises need to be moved laterally to ensure that the test piece 8 and the ball screw assembly are in a straight line. This is achieved by loosening the bolts on the vise clamping plate, then fine-tuning the position of the vises using the fine-tuning plate, and finally tightening the bolts to secure the vises and complete the testing of other guide rail types.

[0074] The load adjustment module 6 has at least one set of lifting components on both sides, and the lead screw tailstock 9 is located between the load adjustment module 6 and one of the sets of lifting components.

[0075] This invention also provides a method for measuring the dynamic friction coefficient of a rolling linear guide pair, applied to the aforementioned dynamic friction coefficient measurement system for rolling linear guide pairs, comprising the following steps:

[0076] S1. Install the measuring module 4, support module 5, load adjustment module 6, and lead screw tailstock 9 onto the marble bed 2 in sequence;

[0077] S2. Install the drive motor 3.2 on the mounting base 3.1. The lead screw 3.3 passes through the measuring module 4 and the support module 5 in sequence, with one end connected to the output end of the drive motor 3.2 and the other end connected to the lead screw tailstock 9.

[0078] S3. Place the test piece 8. One end of the test piece 8 is placed naturally on the single-row needle roller bearing 4.8 on the plane of the measuring platform 4.7. The other end is placed between the opposing sliders 6.5 with the bottom of the opposing sliders 6.5 as the reference. Adjust the height of the support module 5 so that the test piece 8 is parallel to the marble bed 2.

[0079] S4. The running program is set by the drive controller, the drive motor 3.2 drives the lead screw 3.3 to rotate, the lead screw 3.3 drives the entire measuring module 4 to reciprocate, and the tension and pressure sensor 4.4 records the real-time data of the pre-tightening drag force, and then calculates the dynamic friction coefficient of the measured part 8.

[0080] The method for calculating the dynamic friction coefficient includes:

[0081] S401. Obtain the structural parameters, material parameters, and initial preload of the rolling linear guide pair;

[0082] S402. Based on Hertzian contact theory, calculate the initial contact deformation between the ball and the workpiece, and between the ball and the opposing slider, under the initial preload.

[0083] S403. Based on the force balance, deformation coordination relationship and geometric relationship of the top-mounted slider under vertical load, establish a contact load calculation model that includes the influence of elastic deformation of the top-mounted slider skirt; wherein, the deformation of the top-mounted slider skirt is equivalent to the deformation of a cantilever beam fixed at one end at the contact point.

[0084] S404. Substitute the vertical load into the contact load calculation model to solve for the actual contact load between each ball and the test piece.

[0085] S405. Calculate the dynamic friction coefficient based on the measured pre-tightening drag force and the calculated actual contact load.

[0086] The method for calculating the dynamic friction coefficient also includes:

[0087] S411. Based on the force balance of the opposing slider in the horizontal direction, and based on the geometric position changes of the opposing slider and the curvature center of the measured part before and after bearing the measured part, establish the relationship between the contact angle change and the vertical displacement of the opposing slider, the skirt deformation, and the contact deformation.

[0088] S412. Express the deformation of the top-mounted slider skirt as a function of the contact load at the corresponding position; establish the relationship between the vertical displacement, the total contact deformation, and the initial deformation based on the deformation compatibility conditions; combine the above relationships to construct a set of equations for solving the actual contact load.

[0089] The initial contact deformation calculated according to the Hertzian contact theory includes:

[0090] Based on the initial preload, ball diameter, radius of curvature of the test piece, material elastic modulus and Poisson's ratio, calculate the Hertzian contact load-deformation coefficient between the ball and the test piece, and between the ball and the opposing slider.

[0091] The initial contact deformation is calculated using the load-deformation coefficient and the initial preload.

[0092] In one embodiment, such as Figure 6 As shown: Indicates the first The ball and the first A slider raceway or guide rail raceway Contact load between; under external load The vertical displacement generated by the slider under the action and skirt deformation amount Cause the contact angle to change from Become Based on the equilibrium of forces acting on the slider in the horizontal direction, we can conclude that:

[0093] ;

[0094] In the formula, For external load Under the action of the external load, the total internal and external loads borne by one side of the structure; For external load Under the action, the internal load borne by one side of the structure; For external load; For external load Under the action, the structure on the other side bears the sum of internal and external loads, but the force is the same as... on the contrary; For external load Under the action, the structure on the other side bears the internal load; but the force and on the contrary.

[0095] Right now:

[0096] ;

[0097] ;

[0098] In the formula, For the first ball and the second The torque corresponding to the direction of action of each contact load; For the 3rd ball and the 1st ball The torque corresponding to the direction of action of each contact load; For the second ball and the first The torque corresponding to the direction of action of each contact load; For the 4th ball and the 1st ball The torque corresponding to the direction of action of each contact load; For the 6th ball and the 6th ball The torque corresponding to the direction of action of each contact load; For the 8th ball and the 8th ball The torque corresponding to the direction of action of each contact load; For the 5th ball and the 1st ball The torque corresponding to the direction of action of each contact load; For the 7th ball and the 7th ball The torque corresponding to the direction of action of each contact load; The projection coefficient of the angle between the direction of the j-th contact load at the first ball and the horizontal reference direction; The projection coefficient of the angle between the direction of the j-th contact load at the 3rd ball and the horizontal reference direction; The projection coefficient of the angle between the direction of the j-th contact load at the second ball and the horizontal reference direction; The projection coefficient of the angle between the direction of the j-th contact load at the 4th ball and the horizontal reference direction; The projection coefficient of the angle between the direction of the j-th contact load at the 6th ball and the horizontal reference direction; The projection coefficient of the angle between the direction of the j-th contact load at the 8th ball and the horizontal reference direction; The projection coefficient of the angle between the direction of the j-th contact load at the 5th ball and the horizontal reference direction; The projection coefficient of the angle between the direction of the j-th contact load at the 7th ball and the horizontal reference direction; and These are the structural design geometric parameters (such as the total width of the structure, the gap width of hinge nodes, etc.). The difference between these dimensions represents the lever arm length of the ball in the horizontal direction or the horizontal projection spacing of the component; n is the total number of force terms associated with a single ball.

[0099] Depend on Figure 7 It can be observed that when subjected to a load, the relationship between the contact load and the load can be expressed as:

[0100] ;

[0101] The meanings of the parameters in the formula are the same as those above, and will not be repeated here.

[0102] The relationship of contact angles can be expressed as:

[0103] ;

[0104] In the formula, The angle between the direction of the j-th contact load at the first ball and the horizontal reference direction; The angle between the direction of the j-th contact load at the 3rd ball and the horizontal reference direction; The angle between the direction of the j-th contact load at the second ball and the horizontal reference direction; The angle between the direction of the j-th contact load at the 4th ball and the horizontal reference direction; The angle between the direction of the j-th contact load at the 6th ball and the horizontal reference direction; The angle between the direction of the j-th contact load at the 8th ball and the horizontal reference direction; The angle between the direction of the j-th contact load at the 5th ball and the horizontal reference direction; The angle between the direction of the j-th contact load at the 7th ball and the horizontal reference direction.

[0105] For ease of analysis, we can perform a force analysis on balls 3 and 4, i.e., i=3 and i=4. The center of curvature of the guide rail raceway is... It is considered to be fixed in space. Figure 8 Diagram showing the relationship between the curvature centers of the guide rail and slider raceway before and after bearing load. , Each bears a vertical load The center of curvature of the front and rear slider raceways. and Distance between It can be represented as:

[0106] ;

[0107] in, , Indicates the slider raceway adaptation ratio; Indicates the diameter of the ball bearings; The total initial contact deformation between the ball and the slider and guide rail raceway when no vertical load is applied can be expressed as:

[0108] ;

[0109] in, This indicates the initial elastic deformation between the ball and the guide rail raceway at the corresponding position; According to Hertz's elastic contact theory, we can obtain:

[0110] ;

[0111] in, This represents the normal contact load generated between the ball and the guide rail raceway at the corresponding position under the initial preload. This represents the load-deformation coefficient between the ball and the guide rail raceway.

[0112] Hertz contact theory can be expressed as:

[0113] ;

[0114] in, , These represent the elastic moduli of the ball and slider materials, respectively. , These represent the Poisson's ratios of the ball and slider materials, respectively. Indicates the slider raceway adaptation ratio. Indicates the diameter of the ball bearing. Dimensionless coefficient. It can be represented as:

[0115] ;

[0116] in, The eccentricity of the ellipse representing the contact ellipse between the ball and the slider raceway; the first elliptic integral. Second Elliptic Integral They are respectively:

[0117] ;

[0118] ;

[0119] In the formula, The modulus of the corresponding elliptic integral; As an angle variable in mathematical integration, it has no direct physical meaning and is only used in the calculation of elliptic integrals. Its range of values ​​is... This corresponds to a scenario in structural stress analysis where the direction angle of the force covers 0 to 90 degrees, matching the diagram. Angle range.

[0120] Then similar to , The following expression exists:

[0121] ;

[0122] ;

[0123] ;

[0124] ;

[0125] This represents the elastic modulus of the guide rail material. This indicates the Poisson's ratio of the guide rail material. This represents the eccentricity of the contact ellipse between the ball and the slider raceway. The meanings of the other variables are the same as described above, and will not be repeated here.

[0126] according to Figure 8 The geometric relationship in the bearing, the contact angle after bearing It can be represented as:

[0127] ;

[0128] In the formula, the molecule The vertical projection length of the component after deformation is the same as its vertical projection before deformation. Subtract the vertical deformation amount after deformation The denominator is the actual length of the deformed component (using the Pythagorean theorem: the square root of the vertical projection² + the horizontal projection²). Because the structure is subjected to forces on both sides... Since the directions are opposite, the horizontal deformation directions are symmetrical and opposite, so the signs of the deformation terms in the horizontal projection are different.

[0129] Based on the outward expansion of the slider skirt under vertical load in a rolling linear guide pair, the slider side can be equivalent to a cantilever beam fixed at one end, such as... Figure 8 As shown, Indicates the first The vertical distance from the contact point between the slider raceway and the ball to the upper surface of the slider. Under contact load. Under the action, the slider skirt is in The corresponding deformation for:

[0130] ;

[0131] in, This represents the moment of inertia. The meanings of the other variables are the same as those of the parameters mentioned above, and will not be repeated here.

[0132] Vertical displacement Contact deformation The relationship between them is:

[0133] ;

[0134] in, This represents the initial deformation of the slider skirt under no vertical load; the meanings of the other variables are the same as those of the above parameters, and will not be repeated here. For vertical load The total contact deformation between the ball and the slider and guide rail raceway under the action is expressed as:

[0135] The variables in the formula have the same meaning as the parameters mentioned above, and will not be repeated here.

[0136] in, and Contact load and The relationship is:

[0137] ;

[0138] The variables in the formula have the same meaning as the parameters mentioned above, and will not be repeated here.

[0139] Based on the structure and load-bearing characteristics of the rolling linear guide pair, a deformation compatibility relationship exists under vertical load:

[0140] ;

[0141] In the formula, At the first hinge node, the first The related components are Deformation in the direction; At the second hinge node, the... The related components are Deformation in the direction; At the 3rd hinge node, the The related components are Deformation in the direction; At the 4th hinge node, the The related components are Deformation in the direction; At the 5th hinge node, the The related components are Deformation in the direction; At the 6th hinge node, the The related components are Deformation in the direction; At the 7th hinge node, the The related components are Deformation in the direction; At the 8th hinge node, the The related components are The amount of deformation in the direction.

[0142] Therefore, we can conclude that:

[0143] ;

[0144] Based on the above formula, the contact load on each ball of the rolling linear guide pair under load can be obtained. The variables in the formula have the same meaning as the parameters mentioned above, and will not be repeated here.

[0145] Then, the obtained data is processed to calculate the dynamic friction coefficient.

[0146] ;

[0147] In the formula, Indicates the dynamic friction coefficient. This indicates the preload traction force, which is directly measured by the tension / compression sensor. This represents the contact load, which is measured by a pressure sensor and then calculated. .

[0148] The dynamic friction coefficient measurement system for rolling linear guide pairs of the present invention, through the coordinated operation of the drive module, measurement module, support module, and load adjustment module, achieves accurate measurement of the dynamic friction coefficient of the guide pair under simulated load conditions. Its complete working principle is as follows:

[0149] First, the measuring module, support module, load adjustment module, and lead screw tailstock are sequentially installed on the marble bed. The guide rail pair under test adopts a top-to-top mounting method, with the two guide rails connected and fixed by bolts and slotted nuts to ensure vertical alignment and consistent axis. One end of the guide rail is assembled onto the measuring module via a guide rail connecting block of specific specifications, naturally resting on a flat single-row needle roller bearing on the measuring platform; the other end is embedded between the top-to-top sliders of the load adjustment module, using the bottom surface of the top-to-top slider as a reference. By adjusting the height of the lifting component in the support module, the guide rail under test is kept parallel to the surface of the marble bed, ensuring uniform force distribution during the test.

[0150] The load adjustment module employs a precision flat-jaw vise mechanism, with an opposing slider mounted on its jaws. Through a helical force-increasing mechanism, the precision flat-jaw vise can apply a controllable clamping force, simulating vertical loads in actual working conditions. The load force is monitored and displayed in real time by a pressure sensor integrated above the vise. The opposing slider has ball bearings at its four corners, automatically adjusting the contact pressure when clamping the guide rail to ensure uniform load distribution. To test different guide rail models, the fastening bolts of the vise mounting plate can be loosened, the precision flat-jaw vise moved laterally, and its position fine-tuned using a fine-tuning plate to ensure alignment between the guide rail under test and the transmission screw axis.

[0151] The servo motor in the drive module drives a precision leadscrew to rotate via a coupling. The leadscrew passes through the measurement module and engages with a threaded sleeve therein, thereby driving the entire measurement module to reciprocate linearly along the guide rail pair on the marble bed. During the movement, the measured guide rail pair moves together with the measurement module, and its relative motion with the opposing slider simulates the sliding state of the guide rail pair in actual operation. Tension and compression sensors detect the preload required to drag the measured guide rail in real time and transmit the data to the control system.

[0152] Based on the collected preload drag force data, combined with the structural parameters, material properties, and load information of the guide rail pair, the system calculates the actual contact load between each ball and the guide rail / slider using Hertzian contact theory and the elastic deformation model of the slider skirt. Specific steps include:

[0153] Based on the initial preload, calculate the initial contact deformation between the ball and the guide rail and slider;

[0154] Establish the force balance and deformation coordination equations for the top slider under vertical load, taking into account the elastic deformation effect of the slider skirt as a cantilever beam.

[0155] Substitute the measured vertical load into the solution to determine the actual contact load distribution at each contact point.

[0156] Finally, the dynamic friction coefficient is calculated based on the ratio of the preload to the total contact load.

[0157] This system employs a top-mounted guide rail clamping method, enabling direct measurement of the friction coefficient without damaging the original slider structure, making the testing process closer to actual working conditions. Load simulation utilizes a precision flat-jaw clamp and pressure sensor closed-loop control, ensuring high loading accuracy and minimal fluctuation. The support module features an adjustable lifting roller structure to accommodate height differences in guide rails of varying specifications, reducing system errors. The overall structure possesses excellent versatility and adjustability, making it suitable for dynamic friction coefficient testing of various types of rolling linear guide rail pairs.

[0158] Through the above workflow, the system can accurately, stably, and repeatably measure the dynamic friction coefficient of rolling linear guide pairs under simulated real load and motion conditions, providing reliable data support for guide pair design optimization and performance evaluation.

[0159] In summary, the dynamic friction coefficient measurement system for rolling linear guide pairs of this invention can measure linear guides of various specifications and models, with a wide measurement range. It uses a top-mounted guide design, which, compared to previous methods using separate sliders to measure the friction coefficient, allows for measurement without damaging the original slider structure. This avoids errors caused by inertia during slider operation. This linear guide pair dynamic friction coefficient measurement system uses precision flat-jaw pliers for load simulation, featuring high loading accuracy, small load force fluctuation range, and strong stability.

[0160] Based on the preferred embodiments of the present invention described above, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A system for measuring the dynamic friction coefficient of a rolling linear guide pair, characterized in that, include: The test piece includes a support frame, a marble bed, a test piece, and a drive module, a measurement module, a support module, and a load adjustment module mounted on the marble bed. The drive module includes a mounting base, a drive motor, and a lead screw connected to the output end of the drive motor. The lead screw passes through the measurement module and the support module in sequence. The measuring module is slidably connected to the marble bed and threadedly connected to the lead screw; the measuring module includes a main worktable, a fixed table, and a tension / compression sensor mounting base plate; the tension / compression sensor mounting base plate is equipped with a tension / compression sensor, an S-shaped sensor connecting block, a guide rail connecting block, and a single-row flat needle roller bearing located below the guide rail connecting block; The support module includes at least two sets of lifting components and a set of lead screw tailstock. The top of the lifting components abuts against the bottom of the test piece, and the lead screw tailstock is used to support the end of the lead screw. The load adjustment module includes a base plate, a flat-jaw pliers mounting plate, a pressure sensor, a force block, a counter-rotating slider, and a slider fixing component; the counter-rotating slider is used to clamp the test piece, and ball bearings are provided at the four corners of the inner wall to adjust the applied pressure.

2. The dynamic friction coefficient measurement system for a rolling linear guide pair according to claim 1, characterized in that: The fixed platform is provided with a threaded sleeve that mates with the lead screw. The tension / compression sensor, the S-shaped sensor connecting block, and the guide rail connecting block are connected in sequence. The end of the guide rail connecting block is provided with a U-shaped measuring platform. There is at least one set of the planar single-row needle roller bearing, which is located below the measuring platform. The marble bed is provided with a guide rail, and the bottom of the measuring module is provided with a connector that mates with the guide rail.

3. The dynamic friction coefficient measurement system for a rolling linear guide pair according to claim 1, characterized in that: At least two sets of the lifting components are exactly the same size. One set of the lifting components includes a base fixed to the marble bed, a support frame guide plate, a roller bracket, and a support roller. The support frame guide plate has a through hole through which the lead screw can pass. Mounting plates are provided at both ends of one side of the roller bracket, and support rollers for supporting the test piece are installed on opposite sides of the two mounting plates.

4. The dynamic friction coefficient measurement system for a rolling linear guide pair according to claim 1, characterized in that: The precision flat-jaw pliers are fixed above the mounting plate of the flat-jaw pliers. The pressure sensor, force block, top-mounted slider and slider fixing component are all installed above the precision flat-jaw pliers. A fine-tuning fixing plate that can adjust the lateral displacement of the precision flat-jaw pliers is provided on one side of the mounting plate of the flat-jaw pliers.

5. The dynamic friction coefficient measurement system for a rolling linear guide pair according to claim 1, characterized in that: The load adjustment module has at least one set of lifting components on both sides, and the lead screw tailstock is located between the load adjustment module and one of the sets of lifting components.

6. The dynamic friction coefficient measurement system for a rolling linear guide pair according to claim 1, characterized in that: The roller bracket and the support frame guide plate are connected by a telescopic rod.

7. A method for measuring the dynamic friction coefficient of a rolling linear guide pair, applied to the dynamic friction coefficient measuring system for a rolling linear guide pair as described in any one of claims 1 to 6, characterized in that, Includes the following steps: S1. Install the measuring module, support module, load adjustment module, and lead screw tailstock onto the marble bed in sequence. S2. Install the drive motor on the mounting base, and let the lead screw pass through the measuring module and the support module in sequence. Connect one end to the output end of the drive motor and the other end to the lead screw tailstock. S3. Place the workpiece under test. One end of the workpiece is placed naturally on the single-row needle roller bearing on the measuring platform. The other end is placed between the opposing sliders with the bottom of the opposing slider as the reference. Adjust the height of the support module so that the workpiece under test is parallel to the marble bed. S4. The running program is set by the drive controller, the drive motor drives the lead screw shaft to rotate, the lead screw drives the entire measuring module to move back and forth, and the tension and compression sensors record the real-time data of the pre-tightening drag force, and then calculate the dynamic friction coefficient of the measured part.

8. The method for measuring the dynamic friction coefficient of a rolling linear guide pair according to claim 7, characterized in that: The method for calculating the dynamic friction coefficient includes: S401. Obtain the structural parameters, material parameters, and initial preload of the rolling linear guide pair; S402. Based on Hertzian contact theory, calculate the initial contact deformation between the ball and the workpiece, and between the ball and the opposing slider, under the initial preload. S403. Based on the force balance, deformation coordination relationship and geometric relationship of the top-mounted slider under vertical load, establish a contact load calculation model that includes the influence of elastic deformation of the top-mounted slider skirt; wherein, the deformation of the top-mounted slider skirt is equivalent to the deformation of a cantilever beam fixed at one end at the contact point. S404. Substitute the vertical load into the contact load calculation model to solve for the actual contact load between each ball and the test piece. S405. Calculate the dynamic friction coefficient based on the measured pre-tightening drag force and the calculated actual contact load.

9. The method for measuring the dynamic friction coefficient of a rolling linear guide pair according to claim 8, characterized in that: The method for calculating the dynamic friction coefficient also includes: S411. Based on the force balance of the opposing slider in the horizontal direction, and based on the geometric position changes of the opposing slider and the curvature center of the measured part before and after bearing the measured part, establish the relationship between the contact angle change and the vertical displacement of the opposing slider, the skirt deformation, and the contact deformation. S412. Express the deformation of the top-mounted slider skirt as a function of the contact load at the corresponding position; establish the relationship between the vertical displacement, the total contact deformation, and the initial deformation based on the deformation compatibility conditions; combine the above relationships to construct a set of equations for solving the actual contact load.

10. The method for measuring the dynamic friction coefficient of a rolling linear guide pair according to claim 8, characterized in that: The initial contact deformation calculated according to the Hertzian contact theory includes: Based on the initial preload, ball diameter, radius of curvature of the test piece, material elastic modulus and Poisson's ratio, calculate the Hertzian contact load-deformation coefficient between the ball and the test piece, and between the ball and the opposing slider. The initial contact deformation is calculated using the load-deformation coefficient and the initial preload.

Images