Testing method and testing device for micro-motion friction force of hydraulic valve
Through modular design and sealing ring friction model, the problems of existing devices being unable to replace the test piece and having limited test range are solved, accurate measurement and virtual compensation of the sealing ring friction are achieved, and the applicability and accuracy of the test device are improved.
Patent Information
- Application Number
- CN202510802410.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-16
- Publication Date
- 2025-09-26
AI Technical Summary
The existing micro-friction force testing device cannot replace different test parts. The testing device is relatively simple and cannot measure the friction of the sealing ring within the full speed range. In addition, the friction calculation method is complex and not accurate enough.
The test device adopts a modular design, combines measurement components and control components, simulates different motion forms through angle adjustment and micro servo electric cylinder movement, builds a sealing ring friction model, obtains the sealing ring friction value in real time, and compensates for the friction that cannot be measured through a virtual compensation algorithm.
The friction force test of the sealing ring under different motion forms and environments is realized, which expands the test range, improves the test accuracy and efficiency, and makes up for the defects of the existing technology.
Smart Images
Figure CN120702749A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of testing the micro-friction characteristics of hydraulic valves, and in particular to a testing method and a testing device for the micro-friction force of hydraulic valves. Background Art
[0002] As a key component that affects the performance of the hydraulic control system of underwater acoustic equipment, the hydraulic valve provides a strong guarantee for the reliability and stability of the system. The valve core and valve sleeve are the main components that generate friction, so studying their micro-motion characteristics is a key requirement.
[0003] Existing fretting friction testers typically cannot be interchanged with different test parts and are mostly designed to test entire valves. Limited by the size of the test parts, these devices are relatively simple. Furthermore, existing fretting friction testers typically only test friction characteristics in either dry or wet environments.
[0004] Furthermore, existing micro-friction test devices are constrained by equipment sealing requirements. The oil pressure load application area cannot be aligned with the actual operating area of the valve under test, resulting in an inability to measure the friction force experienced when the pressure-bearing side of the seal ring changes, thus limiting friction testing. Furthermore, existing micro-friction friction calculation methods rely on secondary calculations based on experimental results, making it impossible to directly obtain the required friction force during the experiment. Furthermore, offline manual calculations and compensation are inefficient and complex. Summary of the Invention
[0005] In order to address the deficiencies of the above-mentioned prior art, the present invention aims to provide a method and device for testing the micro-friction of hydraulic valves. In the method, according to the motion form of the hydraulic valve core to be tested, the angle between the working platform and the bottom surface of the shell and the motion of the micro servo cylinder are used to obtain the actual friction value of the first sealing ring and the second sealing ring under the corresponding motion form; at the same time, according to the factors affecting the friction of the sealing ring in different motions of the hydraulic valve core to be tested, a model for measuring the friction of the sealing ring in the hydraulic valve to be tested is constructed, thereby obtaining the theoretical friction value of the first sealing ring, the second sealing ring and the third sealing ring under the corresponding motion form. The two are combined to obtain real-time friction data, thereby compensating for the friction of the sealing ring that cannot be measured and improving the test accuracy. By installing a modular design of the measurement component and the control component on the device and cooperating with each other, miniaturization, modularization, portability, storage, and quick disassembly functions are achieved, thereby solving the problem that the friction of the hydraulic valve cannot be measured due to sealing limitations in the uniform, sinusoidal and triangular motion forms within the full speed range.
[0006] Specifically, on one hand, the present invention provides a method for testing the micro-friction force of a hydraulic valve, and the specific implementation steps are as follows: S1. Place the hydraulic valve to be tested in the fixture block of the fixture and secure it with the locking end cap of the fixture. Connect both ends of the hydraulic valve to the tension and pressure sensor and the magnetic vortex disk, respectively, and adjust the measurement reference. S2. According to the motion form of the hydraulic valve spool to be tested, the angle between the working platform and the bottom surface of the housing is adjusted using a hand wheel. According to the different axial motion speeds of the hydraulic valve spool to be tested, the motion form of the micro servo cylinder is adjusted to simulate different motions of the hydraulic valve spool to be tested, and the actual friction force values of the first sealing ring and the second sealing ring under the corresponding motion forms are obtained; S3. Based on the factors affecting the friction force on the sealing ring during different movements of the spool of the hydraulic valve to be tested, a model for measuring the friction force of the sealing ring in the hydraulic valve to be tested is constructed. The specific process is as follows: based on the physical parameters of the sealing ring inner diameter and wire diameter, the relationship between the sealing ring material and friction force is established; based on the factors affecting the deformation of the sealing ring during movement, the relationship between the sealing ring contact stress and friction force is established; based on the loading frequency of the micro servo electric cylinder, the relationship between the micro servo electric cylinder loading frequency and the normal contact stress of the sealing ring is established; based on the presence of burrs on the valve core, the relationship between the density and probability distribution of burrs on the valve core surface and the friction coefficient is established; S4. Inputting the physical parameters of the valve core and the sealing ring of the hydraulic valve to be tested into the friction force model of the sealing ring of the hydraulic valve to be tested embedded in the host computer, performing compensation calculation on the friction force of each sealing ring, and obtaining the theoretical friction force value of the sealing ring; S5. Combine the actual friction value and the theoretical friction value to obtain real-time friction data.
[0007] Preferably, in step S2, the angle includes 0°, 30°, 60°, 120° and 150°, and the motion form of the micro servo cylinder includes uniform speed, sinusoidal and triangular motion forms.
[0008] Preferably, in step S3, the relationship between the sealing ring material and the friction force is expressed as: ; Among them, C 01 and C 10 are the coefficients of the relational expression, W is the strain energy density function, I1 is I2 is the strain invariant.
[0009] Preferably, in step S3, the relationship between the sealing ring contact stress and the friction force is expressed as: ; Where p is the oil pressure load, is the oil pressure inside the first and second sealing rings, d is the wire diameter of the sealing ring, E is the equivalent elastic modulus, Sp is the contact width between the sealing ring and the valve core, and ε is the strain.
[0010] Preferably, in step S3, the relationship between the loading frequency of the micro servo electric cylinder and the normal contact stress of the sealing ring is expressed as follows: ; Among them, k e Model elastic stiffness, k f Model friction stiffness, k v,r Real part of the model viscoelastic stiffness, k v,i Imaginary part of the model's viscoelastic stiffness.
[0011] Preferably, in step S3, the relationship between the density and probability distribution of the burrs on the valve core surface and the friction coefficient is expressed as follows: ; Among them, σ h is the standard deviation describing the burr height distribution, h is the height of the burr on the valve core surface, P(h) is the probability density of the burr height ℎ, Indicates the average height of all burrs on the valve core surface.
[0012] On the other hand, the present invention provides a device for testing the micro-friction force of a hydraulic valve, which includes a measuring component and a control component. The installation and measurement assembly includes a housing, a work platform, a displacement sensor, a displacement sensor fixture, a magnetic vortex disk, a fixing fixture, a bearing seat, a handwheel, a tension and pressure sensor, a micro servo electric cylinder connector, a micro servo electric cylinder, a micro servo electric cylinder fixture and a locker. The rotating end of the work platform is connected to the handwheel through the bearing seat located on the housing. The bearing seat is fastened to the housing. The handwheel is connected to the rotating end of the workbench through a cylindrical pin. The locker is connected to the fixed end of the work platform through the slide groove of the housing. The displacement sensor is connected to the first mounting end of the work platform through the displacement sensor fixture. The fixed end of the fixed tooling is connected to the second mounting end of the work platform, the micro servo electric cylinder is connected to the third mounting end of the work platform through a micro servo electric cylinder fixture, the hydraulic valve to be tested is located in the tooling block of the fixed tooling and is fixed by means of the locking end cover of the fixed tooling, the output end of the micro servo electric cylinder is connected to the quick-release shaft in the micro servo electric cylinder connector, the quick-release sleeve in the micro servo electric cylinder connector is connected to the first end of the tension and pressure sensor, the second end of the tension and pressure sensor is connected to the first end of the hydraulic valve to be tested, and the second end of the hydraulic valve to be tested is connected to the magnetic vortex disk.
[0013] Preferably, the control component includes a force transmitter, a power module, a displacement transmitter, an acquisition card, a host computer, a power indicator light, a displacement display, a power switch, a force display, a speed display and an industrial display screen. The first end of the force transmitter is connected to the output end of the tension and pressure sensor, the first end of the displacement transmitter is connected to the output end of the displacement sensor, the second end of the force transmitter, the second end of the displacement transmitter and the output end of the power module are respectively connected through the acquisition card and the connection end of the host computer. The control panel is provided with a power indicator light, a displacement display, a power switch, a force display, a speed display and an industrial display screen in sequence.
[0014] Preferably, the axes of the displacement sensor, the tension and pressure sensor, the magnetic vortex disk and the micro servo cylinder are on the same straight line.
[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. The test device of the present invention adopts the center position of the fixed tooling to realize the axial quick disassembly of the high-pressure tooling, ensuring axial operation during the entire process of replacing the hydraulic valve to be tested, saving time, avoiding adjustments in other directions, and improving test accuracy.
[0016] 2. The fixed tooling of the present invention can select whether to pass oil through the oil inlet to test the friction under different motion forms, different installation angles, and different speeds under dry and wet conditions. At the same time, the oil inlet is arranged on the rear side of the fixed tooling without affecting the experimental operation, which makes up for the situation that the current micro-friction test device can only test one of the conditions, and expands the scope of application of the test device for micro-friction test conditions.
[0017] 3. The present invention builds a model for measuring the friction force of the sealing ring in the hydraulic valve based on the friction force tested by the hydraulic valve, and adopts a friction force virtual compensation algorithm to compensate for the friction force exerted on the pressure-bearing side of the sealing ring when the hydraulic valve to be tested changes due to the constraints of the sealing requirements, which cannot be measured experimentally. It expands the test range of the micro-friction force between the valve core and the valve sleeve of the hydraulic valve, and makes up for the physical defect of not being able to measure all the sealing rings, thereby obtaining a more accurate friction force of the sealing ring.
[0018] 4. The friction model constructed by the present invention comprehensively considers the relationship between the sealing ring material parameters, the contact stress of the valve core sealing ring, the loading frequency of the micro servo electric cylinder, the normal contact stress of the sealing ring, the density and probability distribution of burrs on the valve core surface and the friction force, so as to facilitate the construction of a virtual compensation algorithm to achieve compensation for the sealing ring friction that cannot be measured.
[0019] 5. The friction compensation algorithm in the present invention expands the test range of friction by building a model for measuring the friction of the sealing ring in the hydraulic valve, and automatically calculates the friction according to the model and related parameters, thereby compensating for the physical defects that cannot be fully measured, thereby ensuring the accuracy of the measurement. Compared with manual compensation, it has the advantages of real-time and fastness and can ensure higher accuracy. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 This is an overall structural diagram of the installation of a measuring assembly in a device for testing the micro-friction force of a hydraulic valve according to the present invention; Figure 2 This is an overall cross-sectional view of the installation of a measuring assembly in a device for testing the micro-friction force of a hydraulic valve according to the present invention; Figure 3 This is an overall structural diagram of the control assembly in the device for testing the micro-friction force of a hydraulic valve according to the present invention; Figure 4 This is a diagram showing the internal structure of a fixed fixture in a device for testing the micro-friction force of a hydraulic valve according to the present invention; Figure 5 is a cross-sectional view of a hydraulic valve to be tested in a device for testing the micro-friction force of a hydraulic valve according to the present invention; Figure 6 This is a flow chart of a method for testing the micro-friction force of a hydraulic valve according to the present invention; Figure 7 This is a diagram showing the friction force test results of each sealing ring of the hydraulic valve to be tested in the device for testing the micro-friction force of the hydraulic valve of the present invention.
[0021] Main reference numerals: Shell 1, working platform 2, displacement sensor 3, displacement sensor fixture 4, magnetic vortex disk 5, fixing tool 6, tooling block 61, locking end cover 62, hexagonal head bolt 7, bearing seat 8, cylindrical pin 9, handwheel 10, tension and pressure sensor 11, micro servo electric cylinder connector 12, quick release sleeve 121, quick release shaft 122, micro servo electric cylinder 13, micro servo electric cylinder fixture 14, locker 15, force transmitter 16, power module 17, displacement transmitter 18, acquisition card 19, host computer 20, power indicator light 21, displacement display 22, power switch 23, force display 24, speed display 25, industrial display 26, hydraulic valve to be tested 27, first sealing ring 271, second sealing ring 272, third sealing ring 273. DETAILED DESCRIPTION
[0022] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0023] A method for testing the micro-friction force of a hydraulic valve, the specific implementation steps are as follows: S1. Place the hydraulic valve 27 to be tested in the fixture block 61 of the fixture 6 and secure it with the locking end cap 62 of the fixture 6. Connect both ends of the hydraulic valve 27 to the tension and pressure sensor 11 and the magnetic vortex 5, respectively. Connect the power to the pressure sensor 11, displacement sensor 3, and micro-servo cylinder 13, and start the micro-servo cylinder 13. This will cause the micro-servo cylinder 13 to move the spool of the hydraulic valve 27 to be tested, which is connected to the pressure sensor 11, horizontally. This will cause the distance between the magnetic vortex disk 5 and the eddy current sensor 3 to change until the value displayed on the displacement display represents the valve spool opening or closing. This can be considered the initial position for friction measurement. Then, adjust the work platform 2 to ensure that the axes of the displacement sensor 3, magnetic vortex disk 5, hydraulic valve 27 to be tested, pressure sensor 11, and micro-servo cylinder 13 are all aligned, i.e., the zero point for friction measurement. This completes the preparations.
[0024] S2. According to the movement form of the spool 27 of the hydraulic valve to be tested, the angle between the working platform 2 and the bottom surface of the housing 1 is adjusted using the hand wheel 10. According to the different axial movement speeds of the spool 27 of the hydraulic valve to be tested, the movement form of the micro servo cylinder 13 is adjusted through the system of the industrial display screen 26, thereby simulating different movements of the spool of the hydraulic valve to be tested 27. After the movement of the spool of the hydraulic valve to be tested 27 is completed, the actual friction force values of the first sealing ring 271 and the second sealing ring 272 under the corresponding movement form are obtained.
[0025] Specifically, the angles include 0°, 30°, 60°, 120° and 150°, and the motion forms of the micro servo electric cylinder include uniform speed, sinusoidal and triangular motion forms.
[0026] S3. Since the current friction test needs to ensure sealing during the process of introducing pressure oil, pressure cannot be input on both the inside and outside of each sealing ring. However, during the operation of various hydraulic valves, the pressure-bearing side of the sealing ring will often switch as the function changes. Forward oil flow is pressurized at the oil port between the first sealing ring 271 and the second sealing ring 272, and the pressure-bearing side of the sealing ring is the inner side of the first sealing ring 271 and the second sealing ring 272; reverse oil flow is pressurized at the oil port on the left side of the first sealing ring 271, and the pressure-bearing side of the sealing ring is the left side of the first sealing ring 271. In order to better measure the friction force of the hydraulic valve under various working conditions, the present invention incorporates a compensation algorithm into the controller of the test bench, and adopts a combination of virtual and real measurement methods to add the effect of the pressure that cannot be actually loaded on the friction force to the measured value.
[0027] Therefore, according to the factors affecting the friction force on the sealing ring of the hydraulic valve 27 to be tested during different movements of the valve core, a model for measuring the friction force of the sealing ring in the hydraulic valve 27 to be tested is constructed. The specific process is as follows: The friction is affected by the physical parameters of the sealing ring, such as the inner diameter and wire diameter, so the rubber Mooney-Rivlin constitutive model is selected; since the sealing ring will produce compression and elongation during the movement of the valve core, which affects the friction, the Mindlin-Deresiewicz contact theory model and the Karaszkiewicz contact model are selected; since the loading frequency of the micro-servo electric cylinder affects the normal contact stress of the sealing ring, the rubber BERG dynamic model is selected; since there are burr defects in the valve core processing process, they will generate friction resistance when puncturing the rubber sealing ring, so the burr shear model is selected. The relationship between the model and the factors affecting friction is established: the rubber Mooney-Rivlin constitutive model establishes the relationship between the sealing ring material parameters and friction, the Mindlin-Deresiewicz contact theory model and the Karaszkiewicz contact model establish the relationship between the valve core sealing ring contact stress and friction, the rubber BERG dynamic model establishes the relationship between the micro-servo electric cylinder loading frequency and the sealing ring normal contact stress, and the burr shear force model establishes the relationship between the density and probability distribution of burrs on the valve core surface and the friction coefficient. Specifically, the relationship between the sealing ring material and the friction force is expressed as: ; Among them, C 01 and C 10 is the coefficient of the relational expression, usually C 01 =0.25C 10 , W is the strain energy density function, I1 is I2 is the strain invariant.
[0028] The relationship between the contact stress and friction force of the sealing ring is expressed as follows: ; Wherein, p is the oil pressure load, p is the oil pressure inside the first sealing ring 271 and the second sealing ring 272, d is the wire diameter of the sealing ring, E is the equivalent elastic modulus, Sp is the contact width between the sealing ring and the valve core, and ε is the strain.
[0029] The relationship between the loading frequency of the micro servo cylinder and the normal contact stress of the sealing ring is expressed as follows: ; Among them, k e Model elastic stiffness, k f Model friction stiffness, k v,r Real part of the model viscoelastic stiffness, k v,i Imaginary part of the model's viscoelastic stiffness.
[0030] The relationship between the density and probability distribution of burrs on the valve core surface and the friction coefficient is expressed as follows: ; Among them, σh is the standard deviation describing the burr height distribution, h is the height of the burr on the valve core surface, and P(h) is the probability density of the burr height ℎ. Indicates the average height of all burrs on the valve core surface.
[0031] S4. Based on the requirements of the model and influencing factors, the seal ring inner diameter, wire diameter, valve core diameter, valve core surface texture period and roughness, average valve core surface burr height, and number of burrs per unit area are input into the controller. During the axial movement of the valve core of the hydraulic valve 27 to be tested, the contact stress distribution and contact area size between the seal ring and the valve core under different input load pressures are first obtained, and then the friction coefficient at each point in the contact area is obtained. The dynamic change data of the contact stress in the contact area is obtained based on the set axial movement speed of the valve core. Based on the measured contact stress and friction coefficient, and in combination with the relevant parameters of the valve core and seal ring, the friction force of each seal ring is compensated and calculated to obtain the theoretical friction force values of the first seal ring 271, the second seal ring 272, and the third seal ring 273.
[0032] S5. Combining the generated virtual friction force with the real-time friction force actually measured by the test bench to obtain real-time data of the virtual and real friction force, and displaying the algorithm-compensated friction force data (Fx curve and data table) on the industrial display screen 26.
[0033] When the micro-friction characteristic test of multiple hydraulic valves to be tested needs to be replaced, first twist the quick-release sleeve 121 of the micro-servo electric cylinder connector 12 to separate the tensile stress sensor 11 from the micro-servo electric cylinder 13, remove the magnetic vortex 5 disks and the tensile pressure sensor 11 on both sides of the fixed tooling 6, then remove the locking end cover 62 at the second end of the fixed tooling 6, and then remove the hydraulic valve 27 to be tested and replace it. Finally, repeat the above steps S1-S5 to obtain the friction force change law of different hydraulic valves.
[0034] In this specific embodiment, the micro-servo electric cylinder 13 is a servo electric push rod with very precise measurement accuracy. It can adjust various motion forms through the control of the upper computer, including position control, speed control, force control, force-speed control and horizontal reciprocating motion. The position control of the micro-servo electric cylinder 13 has a positioning accuracy of micron level. The speed control can be adjusted to a minimum of 8 microns / second, with the maximum displacement reaching 34 mm. The force control can be accurately controlled within the measurement range of 0~105N. Force-speed control can not only ensure the precise control of speed, but also ensure that the force operates stably within the set numerical range. As for the horizontal reciprocating motion, it supports both triangular wave and sine wave forms. The position amplitude can be arbitrarily set between 0~16 mm, and the minimum period can be adjusted to 10 milliseconds.
[0035] Therefore, during the test of the micro-friction force of the hydraulic valve, the micro-servo electric cylinder 13 can be used to flexibly select any of the above modes to achieve dynamic and static friction force measurement of multiple friction pairs, providing high flexibility and accuracy for micro-friction force testing.
[0036] The second aspect of the present invention is as follows Figure 1 As shown in FIG, the device for testing the micro-friction force of a hydraulic valve includes a measuring component and a control component. Figure 2 As shown, the overall installation measurement component adopts a flip structure. When no measurement is performed, the working platform 2 is flipped downward and located inside the shell 1 for easy storage and placement. It includes a shell 1, a working platform 2, a displacement sensor 3, a displacement sensor fixture 4, a magnetic vortex disk 5, a fixing tool 6, a bearing seat 8, a handwheel 10, a tension and pressure sensor 11, a micro servo electric cylinder connector 12, a micro servo electric cylinder 13, a micro servo electric cylinder fixture 14 and a locker 15. The micro servo electric cylinder connector 12 includes a quick-release shaft 122 and a quick-release sleeve 121, which replaces the threaded connection between the tensile stress sensor 11 and the micro servo electric cylinder 13; during disassembly, the tensile stress sensor 11 and the micro servo electric cylinder 13 can be separated by twisting the quick-release sleeve 121, thereby achieving quick disassembly and facilitating replacement of the test piece; the micro servo electric cylinder fixture 14 is a full-coverage type, which can achieve all-round fixation of the micro servo electric cylinder 13 to prevent its displacement from affecting the measurement accuracy; the fixing tool 6 includes a tool block 61 and a locking end cover 62, the center position of which is used to install the hydraulic valve 27 to be tested, and the hydraulic valve 27 to be tested is fixed by the threaded connection between the locking end cover 62 and the tool block 61, and at the same time facilitates axial quick disassembly of the high-pressure tool, ensuring axial operation during the entire replacement process of the hydraulic valve to be tested, saving time, avoiding adjustments in other directions, and improving test accuracy.
[0037] The locker 15 is a bolt with a rotating part. The locker 15 is arranged on the working platform 2, and the locker 15 is arranged in the slide rail of the shell 1. By rotating the locker 15, the working platform 2 is tightly connected to the inner wall of the shell 1, so that the working platform 2 can be accurately fixed at any angle; a measuring scale for measuring the rotation angle value of the working platform 2 is provided on the surface of the shell 1, so that the working platform 2 can be accurately fixed and stopped at any angle for measurement when the working platform 2 rotates circumferentially; the transmission shaft of the working platform 2 is fixed in the shell 1 through the bearing seat 8, and can be rotated by the handwheel 10, and the angle between the working platform 2 and the bottom surface of the shell 1 can be adjusted. The angle adjustment range is 0~180°. By adjusting the angle between the working platform 2 and the bottom surface of the shell 1, the installed measuring component can measure the friction force of the O-ring between the valve core and the valve sleeve at different inclination angles.
[0038] The rotating end of the work platform 2 is connected to the bearing seat 8 and the hand wheel 10 on the housing 1. The bearing seat 8 is fixed to the housing 1 by a hexagonal bolt 7. The hand wheel 10 is connected to the rotating end of the work platform 2 by a cylindrical pin 9. The locker 15 passes through the slide groove of the housing 1 and is connected to the fixed end of the work platform 2. The displacement sensor 3 is connected to the first mounting end of the work platform 2 through the displacement sensor fixture 4. The fixed end of the fixed tool 6 is connected to the second mounting end of the work platform 2. The micro servo electric cylinder 13 is connected to the micro servo electric cylinder fixture 1 4 is connected to the third mounting end of the work platform 2, the hydraulic valve 27 to be tested is located in the tooling block 61 of the fixed tooling 6 and is fixed by the locking end cover 62 of the fixed tooling 6, the output end of the micro servo cylinder 13 is connected to the quick-release shaft 122 in the micro servo cylinder connector 12, the quick-release sleeve 121 in the micro servo cylinder connector 12 is connected to the first end of the tension and pressure sensor 11, the second end of the tension and pressure sensor 11 is connected to the first end of the hydraulic valve 27 to be tested, and the second end of the hydraulic valve 27 to be tested is connected to the magnetic vortex disk 5.
[0039] The control components are integrated, which makes it easy to control the test bench and read the readings at the same time. Figure 3 As shown, it includes a force transmitter 16, a power module 17, a displacement transmitter 18, an acquisition card 19, a host computer 20, a power indicator light 21, a displacement display 22, a power switch 23, a force display 24, a speed display 25, an industrial display screen 26, a digital tube display module and a power button. The first end of the force transmitter 16 is connected to the output end of the tension and pressure sensor 11, the first end of the displacement transmitter 18 is connected to the output end of the displacement sensor 3, the second end of the force transmitter 16, the second end of the displacement transmitter 18 and the output end of the power module 17 are respectively connected through the connection end of the acquisition card 19 and the host computer 20. The control panel is provided with a power indicator light 21, a displacement display 22, a power switch 23, a force display 24, a speed display 25 and an industrial display screen 26 in sequence. The digital tube display module displays the displacement, speed and force respectively. The industrial display screen is equipped with a control system to adjust the mode and speed respectively.
[0040] Furthermore, in order to ensure the accuracy of the test device, the axes of the displacement transmitter 18, the tension and pressure sensor 11, the magnetic vortex disk 5 and the micro servo cylinder 13 are on the same straight line.
[0041] The following is a further description of a method and device for testing the micro-friction force of a hydraulic valve according to the present invention, with reference to an embodiment: S1. Place the hydraulic valve 27 to be tested in the fixture block 61 of the fixture 6 and secure it with the locking end cap 62 of the fixture 6. Connect both ends of the hydraulic valve 27 to the tension and pressure sensor 11 and the magnetic vortex 5, respectively. Connect the power to the pressure sensor 11, displacement sensor 3, and micro-servo cylinder 13, and start the micro-servo cylinder 13. This will cause the micro-servo cylinder 13 to move the spool of the hydraulic valve 27 to be tested, which is connected to the pressure sensor 11, horizontally. This will cause the distance between the magnetic vortex disk 5 and the eddy current sensor 3 to change until the value displayed on the displacement display represents the valve spool opening or closing. This can be considered the initial position for friction measurement. Then, adjust the work platform 2 to ensure that the axes of the displacement sensor 3, magnetic vortex disk 5, hydraulic valve 27 to be tested, pressure sensor 11, and micro-servo cylinder 13 are all aligned, i.e., the zero point for friction measurement. This completes the preparations.
[0042] S2. According to the movement form of the spool 27 of the hydraulic valve to be tested, the angle between the working platform 2 and the bottom surface of the housing 1 is adjusted using the hand wheel 10. According to the different axial movement speeds of the spool 27 of the hydraulic valve to be tested, the movement form of the micro servo cylinder 13 is adjusted through the system of the industrial display screen 26, thereby simulating different movements of the spool of the hydraulic valve to be tested 27. After the movement of the spool of the hydraulic valve to be tested 27 is completed, the actual friction force values of the first sealing ring 271 and the second sealing ring 272 under the corresponding movement form are obtained.
[0043] S3. Based on the factors affecting the friction force on the sealing ring of the hydraulic valve 27 under test during different movements of the valve core, a model for measuring the friction force of the sealing ring of the hydraulic valve 27 under test is constructed. The specific process is as follows: Because physical parameters such as the inner diameter and wire diameter of the seal ring affect friction, the Mooney-Rivlin constitutive model for rubber was selected. Because the seal ring compresses and elongates during valve core movement, affecting friction, the Mindlin-Deresiewicz contact theory model and the Karaszkiewicz contact model were selected. Because the loading frequency of the micro-servo electric cylinder affects the normal contact stress of the seal ring, the BERG dynamic model for rubber was selected. Because burr defects in the valve core processing process generate frictional resistance when puncturing the rubber seal ring, the burr shear model was selected. The relationship between the model and factors affecting friction was established: the Mooney-Rivlin constitutive model for rubber established the relationship between the seal ring material parameters and friction; the Mindlin-Deresiewicz contact theory model and the Karaszkiewicz contact model established the relationship between the valve core seal ring contact stress and friction; the BERG dynamic model established the relationship between the micro-servo electric cylinder loading frequency and the seal ring normal contact stress; and the burr shear force model established the relationship between the density and probability distribution of burrs on the valve core surface and the friction coefficient.
[0044] S4. Based on the requirements of the model and influencing factors, the seal ring inner diameter, wire diameter, valve core diameter, valve core surface texture period and roughness, average valve core surface burr height, and number of burrs per unit area are input into the controller. During the axial movement of the valve core of the hydraulic valve 27 to be tested, the contact stress distribution and contact area size between the seal ring and the valve core under different input load pressures are first obtained, and then the friction coefficient at each point in the contact area is obtained. The dynamic change data of the contact stress in the contact area is obtained based on the set axial movement speed of the valve core. Based on the measured contact stress and friction coefficient, and in combination with the relevant parameters of the valve core and seal ring, the friction force of each seal ring is compensated and calculated to obtain the theoretical friction force values of the first seal ring 271, the second seal ring 272, and the third seal ring 273.
[0045] S5. Combine the generated virtual friction force with the real-time friction force actually measured by the test bench to obtain real-time data of the virtual and real friction force. Display the friction force data after algorithm compensation on the industrial display screen 26 to form an Fx curve and a data table.
[0046] The test results of this specific embodiment are as follows Figure 7 As shown, Figure 7 The friction test device measures the friction curves of the first sealing ring 271, the third sealing ring 273, the first sealing ring 271 and the second sealing ring 272, the first sealing ring 271 and the third sealing ring 273, and the first sealing ring 271 and the second sealing ring 272 and the third sealing ring 273 in the hydraulic valve 27 to be tested, wherein the friction between the first sealing ring 271 and the second sealing ring 272 is the measured value, and the others are the compensated friction values obtained by the friction compensation algorithm. Through the testing method and device of the present invention, the test of the micro-friction of the hydraulic valve is finally realized.
[0047] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.
Claims
1. A method for testing the micro-friction force of a hydraulic valve, characterized in that: The following steps are involved: S1. Place the hydraulic valve to be tested in the fixture block of the fixture and secure it with the locking end cap of the fixture. Connect both ends of the hydraulic valve to the tension and pressure sensor and the magnetic vortex disk, respectively, and adjust the measurement reference. S2. According to the motion form of the hydraulic valve spool to be tested, the angle between the working platform and the bottom surface of the housing is adjusted using a hand wheel. According to the different axial motion speeds of the hydraulic valve spool to be tested, the motion form of the micro servo cylinder is adjusted to simulate different motions of the hydraulic valve spool to be tested, and the actual friction force values of the first sealing ring and the second sealing ring under the corresponding motion forms are obtained; S3. Based on the factors affecting the friction force on the sealing ring during different movements of the spool of the hydraulic valve to be tested, a model for measuring the friction force of the sealing ring in the hydraulic valve to be tested is constructed. The specific process is as follows: based on the physical parameters of the sealing ring inner diameter and wire diameter, the relationship between the sealing ring material and friction force is established; based on the factors affecting the deformation of the sealing ring during movement, the relationship between the sealing ring contact stress and friction force is established; based on the loading frequency of the micro servo electric cylinder, the relationship between the micro servo electric cylinder loading frequency and the normal contact stress of the sealing ring is established; based on the presence of burrs on the valve core, the relationship between the density and probability distribution of burrs on the valve core surface and the friction coefficient is established; S4. Inputting the physical parameters of the valve core and the sealing ring of the hydraulic valve to be tested into the friction force model of the sealing ring of the hydraulic valve to be tested embedded in the host computer, performing compensation calculation on the friction force of each sealing ring, and obtaining the theoretical friction force value of the sealing ring; S5. Combine the actual friction value and the theoretical friction value to obtain real-time friction data.
2. The method for testing the micro-friction force of a hydraulic valve according to claim 1, characterized in that: In step S2, the included angles include 0°, 30°, 60°, 120° and 150°, and the motion forms of the micro servo electric cylinder include uniform speed, sinusoidal and triangular motion forms.
3. The method for testing the micro-friction force of a hydraulic valve according to claim 1, characterized in that: In step S3, the relationship between the sealing ring material and the friction force is expressed as: ； Among them, C 01 and C 10 are the coefficients of the relational expression, W is the strain energy density function, I1 is I2 is the strain invariant.
4. The method for testing the micro-friction force of a hydraulic valve according to claim 1, wherein: In step S3, the relationship between the sealing ring contact stress and the friction force is expressed as: ； Where p is the oil pressure load, is the oil pressure inside the first and second sealing rings, d is the wire diameter of the sealing ring, E is the equivalent elastic modulus, Sp is the contact width between the sealing ring and the valve core, and ε is the strain.
5. The method for testing the micro-friction force of a hydraulic valve according to claim 1, wherein: In step S3, the relationship between the loading frequency of the micro servo cylinder and the normal contact stress of the sealing ring is expressed as follows: ； Among them, k e Model elastic stiffness, k f Model friction stiffness, k v,r Real part of the model viscoelastic stiffness, k v,i Imaginary part of the model's viscoelastic stiffness.
6. The method for testing the micro-friction force of a hydraulic valve according to claim 1, characterized in that: In step S3, the relationship between the density and probability distribution of the burrs on the valve core surface and the friction coefficient is expressed as follows: ； Among them, σ h is the standard deviation describing the burr height distribution, h is the height of the burr on the valve core surface, P(h) is the probability density of the burr height ℎ, Indicates the average height of all burrs on the valve core surface.
7. A testing device for the method for testing the micro-friction force of a hydraulic valve according to any one of claims 1 to 6, characterized in that: It includes installing measurement components and control components, The installation and measurement assembly includes a housing, a work platform, a displacement sensor, a displacement sensor fixture, a magnetic vortex disk, a fixing fixture, a bearing seat, a handwheel, a tension and pressure sensor, a micro servo electric cylinder connector, a micro servo electric cylinder, a micro servo electric cylinder fixture and a locker. The rotating end of the work platform is connected to the handwheel through the bearing seat located on the housing. The bearing seat is fastened to the housing. The handwheel is connected to the rotating end of the workbench through a cylindrical pin. The locker is connected to the fixed end of the work platform through the slide groove of the housing. The displacement sensor is connected to the first mounting end of the work platform through the displacement sensor fixture. The fixed end of the fixed tooling is connected to the second mounting end of the work platform, the micro servo electric cylinder is connected to the third mounting end of the work platform through a micro servo electric cylinder fixture, the hydraulic valve to be tested is located in the tooling block of the fixed tooling and is fixed by means of the locking end cover of the fixed tooling, the output end of the micro servo electric cylinder is connected to the quick-release shaft in the micro servo electric cylinder connector, the quick-release sleeve in the micro servo electric cylinder connector is connected to the first end of the tension and pressure sensor, the second end of the tension and pressure sensor is connected to the first end of the hydraulic valve to be tested, and the second end of the hydraulic valve to be tested is connected to the magnetic vortex disk.
8. The testing device for testing the micro-friction force of a hydraulic valve according to claim 7, characterized in that: The control component includes a force transmitter, a power module, a displacement transmitter, an acquisition card, a host computer, a power indicator light, a displacement display, a power switch, a force display, a speed display and an industrial display screen. The first end of the force transmitter is connected to the output end of the tension and pressure sensor, the first end of the displacement transmitter is connected to the output end of the displacement sensor, the second end of the force transmitter, the second end of the displacement transmitter and the output end of the power module are respectively connected through the acquisition card and the connection end of the host computer. The control panel is provided with a power indicator light, a displacement display, a power switch, a force display, a speed display and an industrial display screen in sequence.
9. The testing device for testing the micro-friction force of a hydraulic valve according to claim 7, characterized in that: The axes of the displacement sensor, the tension and pressure sensor, the magnetic vortex disk and the micro servo electric cylinder are on the same straight line.