Line contact kinematic pair multi-element in-situ measurement method and device

Abstract

The invention discloses a multi-element in-situ measurement method and device for a linear contact kinematic pair, and relates to the technical field of linear contact kinematic pair tests.A cylinder is driven by a driving device to make sliding contact with a sample to be measured, a two-dimensional force sensor collects normal load and tangential friction force borne by the sample, and therefore the friction coefficient is calculated; meanwhile, speckle images before and after the sample is in contact with the cylinder are acquired through an image acquisition device, the surface deformation of the contact pair can be measured in situ based on a digital image correlation method, and the surface contact stress is solved based on an elastic contact mechanics theory; therefore, a linear contact friction lubrication test bed scheme capable of measuring the friction coefficient, the surface deformation and the pressure distribution of the contact area at the same time under different working conditions is formed.

Description

Technical Field

[0001] The invention relates to the technical field of a line contact kinematic pair test bench, and in particular to a multi-element in-situ measurement method and device for a line contact kinematic pair. Background Art

[0002] Line contact pairs are a common type of mechanical kinematic pairs, often found in gears, cylindrical roller bearings, cams and other mechanisms. During the motion of line contact kinematic pairs, the macroscopic mechanical behavior of the material, the surface friction and morphological evolution during service directly affect the service life and motion reliability of mechanical equipment. In the study of the friction and lubrication behavior of line contact kinematic pairs under complex working conditions, the corresponding test platform is indispensable. The existing friction and lubrication test bench is mainly used to measure the friction coefficient, and cannot perform in-situ measurements of other physical quantities. Summary of the invention

[0003] The purpose of the present invention is to provide a multi-element in-situ measurement device for a line contact kinematic pair, aiming to propose a line contact friction lubrication test bench solution that can simultaneously measure the friction coefficient, surface deformation and contact area pressure distribution under different working conditions.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A multi-element in-situ measurement method for a line contact kinematic pair comprises the following steps:

[0006] S1. Install the sample on the sample stage and drive the cylinder to rotate;

[0007] S2, starting an image acquisition device to capture a speckle image A before the sample contacts the cylinder;

[0008] S3, driving the outer vertical surface of the cylinder to slide and contact the sample, and the image acquisition device captures a speckle image B after the sample contacts the cylinder;

[0009] S4, the two-dimensional force sensor collects the normal load and tangential friction force of the sample, and the control device calculates the friction coefficient based on the normal load and the tangential friction force;

[0010] S5, the control device performs digital image correlation analysis on the speckle image A and the speckle image B, and calculates a two-dimensional surface deformation field by performing feature point calculation on the two-dimensional digital image;

[0011] S6. Use the contact mechanics equation to calculate the pressure distribution on the line contact surface.

[0012] A multi-element in-situ measurement device for a line contact kinematic pair, applied to the multi-element in-situ measurement method for a line contact kinematic pair as described above, comprises a work surface, and also comprises:

[0013] A fixed plate, which is fixedly connected to the work surface;

[0014] A movable plate, which is movably arranged between the fixed plate and the work surface;

[0015] A force applying device, comprising a servo motor and a cylinder drivingly connected to an output end of the servo motor;

[0016] One of the fixed plate and the movable plate is provided with a sample stage for mounting the sample to be tested, the sample stage is provided with a two-dimensional force sensor, and the other is provided with the force applying device, and the outer vertical surface of the cylinder faces the sample stage;

[0017] A driving device, whose output end is connected to the moving plate, and the moving plate is driven by the driving device so that the outer side of the cylinder slides to contact or detach from the sample installed on the sample stage;

[0018] A position adjustment device is installed on the work surface, and an image acquisition device is provided at a movable end of the position adjustment device, and the image acquisition device is used to obtain a speckle image before and after the sample contacts the cylinder; and

[0019] The control device is electrically connected to the image acquisition device and the two-dimensional force sensor, and is used to receive the speckle image and collect the normal load and tangential friction force of the sample respectively.

[0020] Furthermore, it comprises a guide rail, one end of which is connected to the fixed plate, the other end of which is connected to the work surface, and the movable plate is movably sleeved on the guide rail.

[0021] Furthermore, it also includes an operating table, which is electrically connected to the driving device and is used to control the extension and retraction of the output end of the driving device.

[0022] Furthermore, a force sensor is provided between the output end of the driving device and the movable plate for monitoring the pressure applied by the driving device.

[0023] Furthermore, a display is included for displaying the pressure monitored by the force sensor.

[0024] Furthermore, the position adjustment device is a three-axis sliding stage, so that the image acquisition device can be moved arbitrarily in a three-dimensional coordinate system.

[0025] Furthermore, the image acquisition device includes a camera and a microscope arranged at the camera lens, and the camera is installed at the moving end of the three-axis sliding stage.

[0026] Furthermore, the force-applying device also includes a base, the base is provided with a groove for containing lubricating liquid, and the cylinder is rotatably mounted in the groove.

[0027] Furthermore, it also includes a bracket, the top surface of the bracket constitutes the working table, and the bottom of the bracket is provided with a plurality of rollers.

[0028] The beneficial effects of the present invention are:

[0029] 1. The present invention proposes a multi-element in-situ measurement method for a line contact kinematic pair. A driving device drives a cylinder to slide and contact a sample to be tested. A two-dimensional force sensor collects the normal load and tangential friction force on the sample, thereby calculating the friction coefficient. At the same time, an image acquisition device is used to obtain a speckle image before and after the sample contacts the cylinder. The surface deformation of the contact pair can be measured in situ based on a digital image correlation method, and the surface contact stress is solved based on the theory of elastic contact mechanics, thereby forming a line contact friction lubrication test bench solution that can simultaneously measure the friction coefficient, surface deformation and contact area pressure distribution under different working conditions.

[0030] 2. The present invention proposes a multi-element in-situ measurement device for a line contact kinematic pair, which includes a guide rail, and a movable plate movably sleeved on the guide rail, so as to reduce the error caused by the left and right shaking of the movable plate during the lifting process.

[0031] 3. The present invention proposes a multi-element in-situ measurement device for a line contact kinematic pair. A force sensor is provided between the output end of the driving device and the movable plate for monitoring the pressure applied by the driving device. At the same time, it also includes a display for displaying the pressure monitored by the force sensor, so that the experimenter can observe the current pressure.

[0032] 4. The present invention proposes a multi-element in-situ measurement device for a line contact kinematic pair, in which the position adjustment device is a three-axis sliding stage, so that the image acquisition device can be moved arbitrarily in a three-dimensional coordinate system, thereby facilitating the acquisition of speckle images before and after the sample contacts the cylinder. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 It is a flow chart of a multi-element in-situ measurement method of a line contact kinematic pair of the present invention;

[0035] Figure 2It is a schematic diagram of a multi-element in-situ measurement device of a line contact kinematic pair of the present invention;

[0036] Figure 3 This is one of the partial schematic diagrams of a multi-element in-situ measurement device of a line contact kinematic pair of the present invention;

[0037] Figure 4 This is a second partial schematic diagram of a multi-element in-situ measurement device for a line contact kinematic pair according to the present invention;

[0038] Figure 5 It is a schematic diagram of an image acquisition device of a multi-element in-situ measurement device of a line contact kinematic pair of the present invention;

[0039] Figure 6 It is a schematic diagram of sample force analysis of a multi-element in-situ measurement device for a line contact kinematic pair of the present invention;

[0040] Figure 7 A schematic diagram of a sample speckle image A of the present invention;

[0041] Figure 8 Schematic diagram of the sample speckle image B of the present invention;

[0042] Fig. 9 It is a schematic diagram of the displacement in the horizontal direction of the sample of the present invention after being compressed;

[0043] Fig.10 It is a schematic diagram of the displacement of the sample of the present invention in the vertical direction after being compressed;

[0044] In the figure, 1. control device; 2. wire; 3. position adjustment device; 4. camera; 5. microscope; 6. two-dimensional force sensor; 7. sample; 8. base; 9. servo motor; 10. display; 11. pressure sensor; 12. bracket; 13. drive device; 14. operating table; 15. moving plate; 16. gear pair; 17. cylinder; 18. roller; 19. support foot; 20. fixed plate. DETAILED DESCRIPTION

[0045] Embodiment 1

[0046] Combine the following Figure 1 The present invention is described in detail.

[0047] This embodiment also proposes a line contact in-situ measurement method as described above, comprising the following steps:

[0048] S1, the sample 7 is mounted on the sample stage, and the servo motor 139 is started to drive the cylinder 17 to rotate;

[0049] S2, start the image acquisition device to capture the speckle image A before the sample 7 contacts the cylinder 17. The speckle image A is as shown in FIG. Figure 7 As shown;

[0050] S3, start the driving device to drive the movable plate 15 to move toward the fixed plate, so that the cylinder 17 slides and contacts the sample 7, and the image acquisition device captures the speckle image B after the sample 7 contacts the cylinder 17. The speckle image B is as shown in Figure 8 As shown;

[0051] S4. At the same time, the two-dimensional force sensor 6 collects the normal load F of the sample 7. N and the tangential friction force F f , its force analysis is as follows Figure 6 As shown, the control device 1 calculates the friction coefficient based on the normal load and the tangential friction force;

[0052] S5, the control device 1 performs digital image correlation analysis on the speckle image A and the speckle image B, and calculates the two-dimensional surface deformation field by performing feature point calculation on the two-dimensional digital image, such as Fig. 9 and Fig.10 shown, specifically, Fig. 9 shows the displacement in the horizontal direction, Fig.10 The amount of displacement in the vertical direction is shown.

[0053] S6. Use the contact mechanics equation to calculate the pressure distribution on the line contact surface.

[0054] In this embodiment, the calculation formula for calculating the friction coefficient f in step S4 is: f=F f / F N , where F f It is as Figure 6 As shown in p, where F N It is as Figure 6 As shown in q.

[0055] In this embodiment, the digital image correlation method mentioned in step S5 is a non-contact modern optical measurement technology, the basic principle of which is to obtain the displacement vector of the pixel point by tracking or matching the position of the same pixel point in the two speckle images before and after the deformation of the object surface, and then obtain the full-field displacement information of the specimen surface.

[0056] In this embodiment, the process of calculating the line contact surface pressure distribution in step S6 is as follows:

[0057] In the process of online contact friction, the semi-analytical method of elastic contact model is combined with the potential theory to solve the deformation relationship of the elastic body under the surface contact pressure, as shown below:

[0058]

[0059] in,

[0060] p is the normal stress on the contact surface, such as Figure 6 As shown;

[0061] q is the shear stress on the contact surface, such as Figure 6 As shown;

[0062] E is the equivalent elastic modulus of the contact pair;

[0063] D is the normal stress-deformation influence coefficient, expressed as D(x)=-ln(x) 2 ;

[0064] T is the tangential stress-deformation influence coefficient, expressed as T(x)=π·E·sgn(x) / 2G, where G is the difference in shear modulus of the material, expressed as , where E1 and E2 are the elastic moduli of the sample and the cylinder; ν1 and ν2 are the Poisson's ratios of the sample and the cylinder, respectively.

[0065] For ease of calculation, write it in discrete form:

[0066]

[0067] in ; , where , , .

[0068] Then, according to the variational method, the surface pressure and shear force of the line contact are solved to obtain the surface stress information.

[0069] In this embodiment, the above calculation formula can be organized into an algorithm program and entered into the control device. After the control device obtains relevant data, it can realize automatic calculation. The programming process belongs to the existing technology and will not be repeated here.

[0070] Embodiment 2

[0071] Combine the following Figure 2-Figure 4 The present invention is described in detail.

[0072] This embodiment further provides a multi-element in-situ measurement device for a line contact kinematic pair, which is applied to the multi-element in-situ measurement method for a line contact kinematic pair as described above, including a work surface, and further comprising:

[0073] A fixed plate 20, which is fixedly connected to the work surface;

[0074] A movable plate 15 is movably disposed between the fixed plate 20 and the work surface;

[0075] The force applying device includes a servo motor 9 and a cylinder 17 which is transmission-connected to the output end of the servo motor 9; further, the force applying device also includes a base 8, on which a rotatable cylinder 17 is provided, the servo motor 9 is mounted on one side of the base 8, and the servo motor 9 is transmission-connected to the cylinder 17 through a gear pair 16;

[0076] The fixed plate 20 is provided with a sample stage for mounting the sample 7 to be tested, the sample stage is provided with a two-dimensional force sensor 6, the movable plate 15 is provided with a force applying device, and the outer vertical surface of the cylinder 17 faces the sample stage; in other embodiments, the movable plate 15 may also be provided with a sample stage, and the fixed plate 20 may be provided with a force applying device;

[0077] A driving device 13, whose output end is connected to the moving plate 15, drives the moving plate 15 through the driving device 13, so that the outer side of the cylinder 17 slides to contact or detach from the sample 7 installed on the sample stage;

[0078] A position adjustment device 3 is installed on the work surface. The moving end of the position adjustment device 3 is provided with an image acquisition device, and the image acquisition device is used to obtain the speckle image before and after the sample 7 contacts the cylinder 17; and,

[0079] The control device 1 is electrically connected to the image acquisition device and the two-dimensional force sensor 6 through the wire 2, and is used to receive the speckle image and collect the normal load and tangential friction force on the sample 7 respectively.

[0080] In this embodiment, a guide rail is included, one end of which is connected to the fixed plate 20, and the other end of the guide rail is connected to the work surface. The movable plate 15 is movably mounted on the guide rail to reduce the possibility of the two-dimensional force sensor 6 having a collection error due to the left and right shaking of the movable plate 15 during the lifting process.

[0081] In this embodiment, an operating table 14 is also included, which is electrically connected to the driving device 13 and is used to control the extension and retraction of the output end of the driving device 13.

[0082] In this embodiment, a pressure sensor 11 is provided between the output end of the driving device 13 and the movable plate 15 for monitoring the pressure applied by the driving device 13; a display 10 is also included for displaying the pressure monitored by the pressure sensor 11, so that the experimenter can observe the current pressure.

[0083] In this embodiment, the position adjustment device 3 is a three-axis sliding stage, and the moving end of the three-axis sliding stage can move in the X-axis, Y-axis and Z-axis directions, so that the image acquisition device can move arbitrarily in the three-dimensional coordinate system. The image acquisition device includes a camera 4 and a microscope 5 arranged at the lens of the camera 4, and the camera 4 is installed at the moving end of the three-axis sliding stage. Further, the image acquisition device also includes a plurality of light sources to facilitate the acquisition of clear speckle images.

[0084] In this embodiment, the force-applying device also includes a base 8, which is provided with a groove for containing lubricating fluid. The cylinder 17 can be rotatably installed in the groove. Different lubricating fluids can be added to the groove according to experimental requirements, so as to study the mechanical performance of the line contact kinematic pair under different lubrication conditions.

[0085] In this embodiment, a bracket 12 is also included, the top surface of the bracket 12 constitutes a work surface, and a plurality of rollers 18 are provided at the bottom of the bracket 12. Further, a plurality of movable support feet 19 are provided at the bottom of the bracket 12, which are used to lift the rollers 18 off the ground, or put down the rollers 18 to abut against the ground.

[0086] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable those skilled in the art to understand the content of the present invention and implement it, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A multi-element in-situ measurement method for a line contact kinematic pair, characterized in that: The steps include: S1. Install the sample on the sample stage and drive the cylinder to rotate; S2, starting an image acquisition device to capture a speckle image A before the sample contacts the cylinder; S3, driving the outer vertical surface of the cylinder to slide and contact the sample, and the image acquisition device captures a speckle image B after the sample contacts the cylinder; S4, the two-dimensional force sensor collects the normal load and tangential friction force of the sample, and the control device calculates the friction coefficient based on the normal load and the tangential friction force; S5, the control device performs digital image correlation analysis on the speckle image A and the speckle image B, and calculates a two-dimensional surface deformation field by performing feature point calculation on the two-dimensional digital image; S6. Use the contact mechanics equation to calculate the pressure distribution on the line contact surface.

2. A multi-element in-situ measurement device for a line contact kinematic pair, applied to the multi-element in-situ measurement method for a line contact kinematic pair as claimed in claim 1, characterized in that: Including work surface, also includes: A fixed plate, which is fixedly connected to the work surface; A movable plate, which is movably arranged between the fixed plate and the work surface; A force applying device, comprising a servo motor and a cylinder drivingly connected to an output end of the servo motor; One of the fixed plate and the movable plate is provided with a sample stage for mounting the sample to be tested, the sample stage is provided with a two-dimensional force sensor, and the other is provided with the force applying device, and the outer vertical surface of the cylinder faces the sample stage; A driving device, whose output end is connected to the moving plate, and the moving plate is driven by the driving device so that the outer side of the cylinder slides to contact or detach from the sample installed on the sample stage; A position adjustment device is installed on the work surface, and an image acquisition device is provided at a movable end of the position adjustment device, and the image acquisition device is used to obtain a speckle image before and after the sample contacts the cylinder; and The control device is electrically connected to the image acquisition device and the two-dimensional force sensor, and is used to receive the speckle image and collect the normal load and tangential friction force of the sample respectively.

3. A multi-element in-situ measurement device for a line contact kinematic pair as claimed in claim 2, characterized in that: It comprises a guide rail, one end of which is connected to the fixed plate, the other end of which is connected to the work surface, and the movable plate is movably sleeved on the guide rail.

4. A multi-element in-situ measurement device for a line contact kinematic pair as claimed in claim 2, characterized in that: It also includes an operating table, which is electrically connected to the driving device and is used to control the extension and retraction of the output end of the driving device.

5. A multi-element in-situ measurement device for a line contact kinematic pair as claimed in claim 2, characterized in that: A force sensor is provided between the output end of the driving device and the moving plate for monitoring the pressure applied by the driving device.

6. A multi-element in-situ measurement device for a line contact kinematic pair as claimed in claim 5, characterized in that: A display is also included for displaying the pressure monitored by the force sensor.

7. A multi-element in-situ measurement device for a line contact kinematic pair as claimed in claim 2, characterized in that: The position adjustment device is a three-axis sliding platform, so that the image acquisition device can be moved arbitrarily in a three-dimensional coordinate system.

8. A multi-element in-situ measurement device for a line contact kinematic pair as claimed in claim 7, characterized in that: The image acquisition device includes a camera and a microscope arranged at the camera lens, and the camera is installed at the moving end of the three-axis sliding stage.

9. A multi-element in-situ measurement device for a line contact kinematic pair as claimed in claim 2, characterized in that: The force applying device also includes a base, the base is provided with a groove for containing lubricating liquid, and the cylinder is rotatably installed in the groove.

10. The multi-element in-situ measurement device of a line contact kinematic pair according to claim 2, characterized in that: It also includes a bracket, the top surface of the bracket constitutes the working table surface, and the bottom of the bracket is provided with a plurality of rollers.

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