Local friction simulation testing machine for sealing pair of control valve

Abstract

The invention discloses a local friction simulation testing machine for a sealing pair of a control valve, which comprises a box body, a driving transmission system, a mounting shaft, a lower test piece rotary friction quick-change assembly or a lower test piece linear reciprocating motion quick-change assembly, a support frame, a loading assembly, an in-situ observation system and a data acquisition and control system, and is characterized in that the driving transmission system is mounted in the box body; the mounting shaft is positioned above the box body and is connected with the driving transmission system through the coupler; the lower test piece rotary friction quick-change assembly or the lower test piece linear reciprocating motion quick-change assembly is mounted on the mounting shaft; the support frame is mounted at the top of the box; the loading assembly is mounted on the support frame in a penetrating manner and corresponds to the position of the lower test piece rotary friction quick-change assembly or the lower test piece linear reciprocating motion quick-change assembly below the loading assembly; the in-situ observation system is mounted on the side surface of the support frame and aligned to the bottom of the loading assembly; the in-situ observation system and the loading assembly are electrically connected with the data acquisition and control system. The real motion trail of the control valve sealing pair is simulated, and the accuracy is improved.

Description

Technical Field

[0001] The invention relates to the technical field of friction test equipment, and more particularly to a control valve sealing pair local friction simulation test machine. Background Art

[0002] During the operation of a machine or instrument, friction and wear between parts in contact with each other is inevitable. Unnecessary friction and wear will cause material deformation and affect the service life of the material. According to different working conditions, friction and wear testers are divided into general friction and wear testers and special friction and wear testers. General friction and wear testers include multifunctional friction and wear testers, four-ball friction and wear testers, pin-disc friction and wear testers, reciprocating friction and wear testers, ring-block friction and wear testers, etc. Among them, the four-ball friction and wear tester is mainly used to detect the quality of lubricating oil, the reciprocating friction and wear tester is mainly used to measure the friction and wear properties of materials that perform reciprocating motion, and the ring-block friction and wear tester is mainly used to measure the friction properties of materials and the properties of lubricating oil.

[0003] At present, the research on ball valves is mainly reflected in the fixing type, clearance setting and material combination of valve core, valve seat and valve stem. At present, there are three structures of valve core fixing type: bearing type, sub-spindle and floating type. The valve seat has spring preload type and passive clamping type. The corresponding shaft is mainly divided into two-way fixed type and one-way fixed type. The high-temperature clearance setting is directly related to the assembly of parts and the actual use temperature. For ball valves with temperatures greater than 300℃ and pressures greater than 10MPa, the valve body is made of high-temperature resistant stainless steel, and the valve trim is made of high-nickel-based materials and surface hardened. From the use situation, the leakage of ball valves with temperatures greater than 300℃ and pressures greater than 10MPa exceeds the standard requirements after more than 50 times of use. The main failure forms are seal erosion and friction wear. At present, the external butterfly valve is mainly represented by the three-eccentric butterfly valve, and the sealing form is forced sealing. The complex sealing surface of the three-eccentric butterfly valve is the main reason for the difficulty in sealing the high-temperature and high-pressure butterfly valve. Under the action of high temperature and high pressure, the deformation of the complex surface makes it difficult for the sealing surface to fully match, the stress distribution is uneven, and friction, wear and leakage occur.

[0004] With regard to the above-mentioned local friction and wear problem of the control valve sealing pair, the existing friction and wear testing machine cannot achieve the purpose of simulation measurement.

[0005] For example, in the invention patent CN108037069A, a friction disc and a friction pin for friction testing are provided on the table of the test bench. The friction disc is driven to rotate by a driving device arranged in the test bench, and the friction pin is connected to an adjustment device fixed on the test bench and used to adjust the pressure and position between the friction pin and the friction disc. However, on the one hand, the existing test bench lacks a quick change module, and cannot be converted from a rotary friction meter to a linear reciprocating friction meter. It is not easy to convert and unlock new test functions, so it is impossible to simulate the real motion trajectory of the control valve sealing pair; on the other hand, the upper and lower samples cannot be replaced quickly, and the requirements of multiple groups of sample control tests cannot be met. In addition, the existing test bench can only observe the friction conditions of the samples in the early and late stages of friction, and lacks in-situ observation of the samples during the entire friction process, resulting in the inability to analyze the effects of different processing techniques, different friction forms, different materials, and different hardening methods of surface materials on the friction and wear conditions of the sealing pair throughout the entire process.

[0006] For another example, in the utility model patent CN212255026U, considering that the primary weight tray can hold a limited number of weights, resulting in a limited test range, a lever frame is provided on one side of the fixed frame. The lever frame is a square vertical pole with a slotted top portion of the vertical pole forming a U-shaped setting, and then a lever is connected to the shaft. A secondary weight tray is provided at one end of the lever away from the lever frame, and the lever is provided above the primary weight tray. A weight anti-drop rod is provided in the middle of the secondary weight tray, and the secondary weight tray is fixed to one end of the lever through the weight anti-drop rod. In this way, through the setting of the secondary weight tray and utilizing the principle of lever, the pressure generated by the weights on the secondary weight tray is transmitted to the test shaft, thereby achieving the purpose of secondary pressurization. However, on the one hand, the load applied between the upper sample and the lower sample cannot be adjusted; on the other hand, the existing load can only be loaded in a 90-degree direction, and the direction of the applied load cannot be changed, resulting in a limited test load applied to the sealing pair of the ball valve and the butterfly valve.

[0007] Therefore, providing a control valve sealing pair local friction simulation test machine is a problem that technical personnel in this field urgently need to solve.

[0008] invention

[0009] In view of this, the present invention provides a control valve sealing pair local friction simulation testing machine, which can simulate the real motion trajectory of the control valve sealing pair and obtain accurate test data.

[0010] In order to achieve the above object, the present invention adopts the following technical solution:

[0011] A control valve sealing pair local friction simulation test machine comprises a housing, an active transmission system, a mounting shaft, a lower specimen rotation friction quick-change assembly or a lower specimen linear reciprocating motion quick-change assembly, a support frame, a loading assembly, an in-situ observation system and a data acquisition and control system, wherein the active transmission system is installed inside the housing; the mounting shaft is located above the housing, and the mounting shaft is connected to the active transmission system through a coupling; the lower specimen rotation friction quick-change assembly or the lower specimen linear reciprocating motion quick-change assembly is installed on the mounting shaft; the support frame is installed on the top of the housing; the loading assembly is installed on the support frame and corresponds to the position of the lower specimen rotation friction quick-change assembly or the lower specimen linear reciprocating motion quick-change assembly below it; the in-situ observation system is installed on the side of the support frame and aligned with the bottom of the loading assembly; the in-situ observation system and the loading assembly are electrically connected to the data acquisition and control system respectively.

[0012] Furthermore, the lower specimen linear reciprocating motion quick-change assembly includes a plurality of reciprocating friction platform brackets, a platform frame, two slide rails, two sliders, a mobile platform, two racks and a half gear, wherein the plurality of reciprocating friction platform brackets are vertically mounted on the top of the box body; the platform frame is mounted on the plurality of reciprocating friction platform brackets; the two slide rails are correspondingly mounted on the two side surfaces of the platform frame; the two sliders are embedded and mounted on the two slide rails; the mobile platform is fixed on the two sliders; the two racks are correspondingly fixed on the inner sides of the mobile platform; the half gear is mounted on the mounting shaft and is alternately meshed with the two racks.

[0013] Furthermore, the lower specimen rotating friction quick-change assembly includes a lower specimen tray and a lower specimen pressure plate, the lower specimen tray is installed on the mounting shaft; the lower specimen tray has a groove for supporting the lower specimen; the lower specimen pressure plate is connected to the lower specimen tray by bolts and pressed onto the lower specimen.

[0014] Furthermore, the loading assembly includes a hydraulic cylinder and a ball joint block, the hydraulic cylinder is vertically installed on the support frame; the ball joint block is connected to the telescopic rod of the hydraulic cylinder through a conversion joint; the bottom of the ball joint block has a slot for fixing the upper specimen; the hydraulic cylinder is electrically connected to the data acquisition and control system.

[0015] Furthermore, it also includes an angle ruler and a retaining ring, wherein the angle ruler is fixed on the top of the support frame, and the angle ruler has an arc groove; the retaining ring is sleeved and fixed on the cylinder body of the hydraulic cylinder; the top of the support frame has a translation hole, and the cylinder body of the hydraulic cylinder passes through the translation hole; the retaining ring is slidably connected to the arc groove through a connecting rod.

[0016] Furthermore, the active transmission system includes a servo motor, a first bevel gear, a second bevel gear, a first shaft, a second shaft, a driving wheel, a driven wheel and a synchronous belt, the first bevel gear is installed on the output shaft of the servo motor; the first shaft is vertically installed in the housing through a bearing seat; the second bevel gear is installed on the first shaft and meshingly connected with the first bevel gear; the second shaft is vertically installed in the housing through a bearing seat and is distributed parallel to the first shaft, and the top end of the second shaft is connected to the mounting shaft through the coupling; the driving wheel is installed on the first shaft, the driven wheel is installed on the second shaft, and the driving wheel and the driven wheel are connected through the synchronous belt transmission.

[0017] Furthermore, the lower test piece is made of a transparent material and is in a semi-circular or boss shape.

[0018] Furthermore, the in-situ observation system includes a 3D laser profiler and a high-speed industrial camera, and the 3D laser profiler and the high-speed industrial camera are electrically connected to a computer through the data acquisition and control system, respectively.

[0019] It can be seen that the present invention provides a control valve sealing pair local friction simulation test machine. Compared with the prior art, the present invention produces the following beneficial effects:

[0020] 1) The present invention includes a lower test piece rotation friction quick-change assembly and a lower test piece linear reciprocating motion quick-change assembly, both of which can be quickly replaced, and can convert rotational motion into precise linear reciprocating friction motion, wherein the rotational motion simulates the friction of the ball valve sealing surface, and the linear reciprocating friction simulates the friction of the butterfly valve sealing surface, thereby satisfying the real motion trajectory of the control valve sealing pair, and is easy to install and convenient to replace;

[0021] 2) The support frame can meet the rotation and parallel movement of the hydraulic cylinder and ensure the stability of the structure. The hydraulic cylinder can rotate according to the angle marked by the angle ruler under the cooperation of the connecting rod and the arc groove, so as to achieve precise control of the rotation angle;

[0022] 3) The combination of the hydraulic cylinder and the ball bearing hinge block of the present invention, on the one hand, the hydraulic cylinder can provide a variety of load sizes, such as light load and heavy load, for the upper and lower test specimens; on the other hand, the rotation of the ball bearing hinge block drives the hydraulic cylinder above it to rotate or move parallel, but it can always ensure that the upper test specimen and the lower test specimen are always in normal contact, thereby realizing multi-angle load application to simulate the actual motion trajectory of the control valve sealing pair.

[0023] 4) Aim the 3D laser profiler and high-speed industrial camera at the upper sample. When the upper sample rotates or rubs back and forth to the lower sample, the 3D laser profiler and high-speed industrial camera begin to collect the sample surface height information before, during and after the friction, establish the three-dimensional morphology of the sample and the actual wear condition of the sample surface, generate high-density point cloud data in real time, accurately record the information of each point of the sample, and realize in-situ observation of the entire process of the friction sample. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present 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 embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0025] Figure 1 The accompanying drawing is a schematic diagram of the overall structure of a control valve sealing pair local friction simulation test machine provided by the present invention during a linear reciprocating friction motion test;

[0026] Figure 2 The accompanying drawing is a schematic diagram of the overall structure of a control valve sealing pair local friction simulation test machine provided by the present invention during a rotational friction motion test;

[0027] Figure 3 The accompanying drawing is a front view of a control valve sealing pair local friction simulation test machine provided by the present invention;

[0028] Figure 4 The accompanying drawing is a schematic structural diagram of a lower test piece linear reciprocating motion quick-change assembly provided by the present invention;

[0029] Figure 5 The accompanying drawing is an exploded view of the lower test piece linear reciprocating motion quick-change assembly provided by the present invention;

[0030] Figure 6 The accompanying drawing is an exploded view of the lower test piece rotating friction quick-change assembly provided by the present invention. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] like Figure 1-6As shown, an embodiment of the present invention discloses a control valve sealing pair local friction simulation test machine, including a housing 1, an active transmission system 2, a mounting shaft 3, a lower specimen rotation friction quick-change assembly 4 or a lower specimen linear reciprocating motion quick-change assembly 5, a support frame 6, a loading assembly 7, an in-situ observation system 8 and a data acquisition and control system 9, wherein the active transmission system 2 is installed inside the housing 1; the mounting shaft 3 is located above the housing 1, and the mounting shaft 3 is connected to the active transmission system 2 through a coupling 10; the lower specimen rotation friction quick-change assembly 4 or the lower specimen linear reciprocating motion quick-change assembly 5 is installed on the mounting shaft 3; the support frame 6 is installed on the top of the housing 1; the loading assembly 7 is installed through the support frame 6 and corresponds to the position of the lower specimen rotation friction quick-change assembly 4 or the lower specimen linear reciprocating motion quick-change assembly 5 below it; the in-situ observation system 8 is installed on the side of the support frame 6 and is aligned with the bottom of the loading assembly 7; the in-situ observation system 8 and the loading assembly 7 are electrically connected to the data acquisition and control system 9 respectively. The lower specimen rotation friction quick-change assembly 4 and the lower specimen linear reciprocating motion quick-change assembly 5 of the present invention can be quickly replaced, and can be disassembled and replaced when necessary, converting the rotational motion into linear reciprocating friction motion, wherein the rotational motion simulates the friction of the ball valve sealing surface, and the linear reciprocating friction simulates the friction of the butterfly valve sealing surface, thereby satisfying the actual motion trajectory of the control valve sealing pair.

[0033] Specifically, the lower specimen linear reciprocating motion quick-change assembly 5 includes multiple reciprocating friction platform brackets 51, a platform frame 52, two slide rails 53, two sliders 54, a mobile platform 55, two racks 56 and a half gear 57. The multiple reciprocating friction platform brackets 51 are vertically installed on the top of the box body 1; the platform frame 52 is installed on the multiple reciprocating friction platform brackets 51; the two slide rails 53 are correspondingly installed on the two side surfaces of the platform frame 52; the two sliders 54 are embedded and installed on the two slide rails 53; the mobile platform 55 is fixed on the two sliders 54; the two racks 56 are correspondingly fixed on the inner sides of the mobile platform 55; the half gear 57 is installed on the mounting shaft 3 and is alternately meshed with the two racks 56. During operation, the mounting shaft 3 drives the half gear 57 to rotate. When the half gear 57 rotates to engage with the rack 56 on the left side of the mobile platform 55, the mobile platform 55 and the lower test piece 11 thereon are driven to move backward along the slide rail 53 on the slider 54. When the half gear 57 rotates to engage with the rack 56 on the right side of the mobile platform 55, the lower test piece 11 is driven to move forward, thereby realizing linear reciprocating motion of the lower test piece 11.

[0034] Specifically, the lower specimen rotating friction quick-change assembly 4 includes a lower specimen tray 41 and a lower specimen pressure plate 42. The lower specimen tray 41 is installed on the mounting shaft 3; the lower specimen tray 41 has a groove 411 for supporting the lower specimen; the lower specimen pressure plate 42 is connected to the lower specimen tray 41 by bolts and pressed onto the lower specimen 11.

[0035] Specifically, the loading assembly 7 includes a hydraulic cylinder 71 and a ball joint block 72. The hydraulic cylinder 71 is vertically installed on the support frame 6. The hydraulic cylinder 71 is supplied with oil by a hydraulic station. The hydraulic station supplies oil according to the flow direction, pressure and flow required by the driving device. The hydraulic station is connected to the hydraulic cylinder 71 with an oil pipe, and the hydraulic cylinder 71 can achieve the specified loading action; the ball joint block 72 is connected to the telescopic rod of the hydraulic cylinder 71 through a conversion joint. The external thread at the front end of the hydraulic cylinder 71 is screwed into the internal thread end of one end of the conversion joint until it is tightened in place. Similarly, the external thread part of the ball joint block 72 is screwed into the internal thread end of the other end of the conversion joint until it is tightened in place; the bottom of the ball joint block 72 has a slot for fixing the upper specimen 12; the hydraulic cylinder 71 is electrically connected to the data acquisition and control system 9, and the ball joint block 72 can ensure that the friction pair position (the contact position between the upper specimen 12 and the lower specimen 11) always remains parallel, and the direction of applied load can be controlled by rotating the ball joint block 72. The hydraulic cylinder 71 and the ball joint block 72 of the present invention are combined. On the one hand, the hydraulic cylinder 71 can provide light loads and heavy loads of various sizes for the upper and lower test specimens. On the other hand, the ball joint block 72 is rotated to drive the hydraulic cylinder 71 above it to rotate or move parallelly, but it can always be ensured that the upper test specimen 12 and the lower test specimen 11 are always in normal contact, thereby realizing multi-angle load application to simulate the actual motion trajectory of the control valve sealing pair.

[0036] Specifically, it also includes an angle ruler 13 and a retaining ring 14. The angle ruler 13 is fixed on the top of the support frame 6, and the angle ruler 13 has an arc groove; the retaining ring 14 is fitted and fixed on the cylinder body of the hydraulic cylinder 71. In this embodiment, there are two retaining rings 14, which are distributed up and down; the top of the support frame 6 has a translation hole 61, and the cylinder body of the hydraulic cylinder 71 passes through the translation hole 61; the retaining ring 14 is slidably connected to the arc groove through a connecting rod, and the support frame 6 can meet the rotation and parallel movement of the hydraulic cylinder 71 and ensure the stability of the structure. The hydraulic cylinder 71 can rotate according to the angle marked by the angle ruler 13 in cooperation with the connecting rod and the arc groove, thereby realizing precise control of the rotation angle.

[0037] Specifically, the active transmission system 2 includes a servo motor 21, a first bevel gear 22, a second bevel gear 23, a first shaft 24, a second shaft 25, a driving wheel, a driven wheel and a synchronous belt 26. The first bevel gear 22 is installed on the output shaft of the servo motor 21; the first shaft 24 is vertically installed in the housing 1 through a bearing seat 27; the second bevel gear 23 is installed on the first shaft 24 and meshingly connected with the first bevel gear 22; the second shaft 25 is vertically installed in the housing 1 through a bearing seat and is distributed parallel to the first shaft 24. The top of the second shaft 25 is connected to the mounting shaft 3 through a coupling 10. A dual differential Hall effect speed sensor and a single digital Hall effect speed sensor are installed on the second shaft 25 to monitor the rotation speed of the second shaft 25 in real time and transmit the data to the data acquisition and control system 9; the driving wheel is installed on the first shaft 24, the driven wheel is installed on the second shaft 25, and the driving wheel and the driven wheel are connected through a synchronous belt 26. During operation, the servo motor 21 drives the first shaft 24 to rotate through the bevel gear set, the first shaft 24 drives the second shaft 25 to rotate through the synchronous belt assembly, and the second shaft 25 drives the installation shaft 3 to rotate through the coupling 10.

[0038] Specifically, the lower test piece 11 is made of transparent metal and is in a semi-circular or boss shape. The in-situ observation system includes a 3D laser profiler and a high-speed industrial camera, which are electrically connected to the computer through the data acquisition and control system 9. When working, the 3D laser profiler and the high-speed industrial camera are aimed at the upper test piece 12. When the upper test piece 12 rotates or reciprocates to rub against the lower test piece 11, the 3D laser profiler and the high-speed industrial camera begin to collect the sample surface height information before, during and after the friction, establish the three-dimensional morphology of the sample and the actual wear condition of the sample surface, generate high-density point cloud data in real time, accurately record the information of each point of the sample, and realize the in-situ observation of the whole process of the friction sample.

[0039] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0040] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A control valve sealing pair local friction simulation test machine, characterized in that: It includes a box, an active transmission system, a mounting shaft, a lower specimen rotation friction quick-change assembly or a lower specimen linear reciprocating motion quick-change assembly, a support frame, a loading assembly, an in-situ observation system and a data acquisition and control system, wherein the active transmission system is installed inside the box; the mounting shaft is located above the box, and the mounting shaft is connected to the active transmission system through a coupling; the lower specimen rotation friction quick-change assembly or the lower specimen linear reciprocating motion quick-change assembly is installed on the mounting shaft; the support frame is installed on the top of the box; the loading assembly is installed on the support frame and corresponds to the position of the lower specimen rotation friction quick-change assembly or the lower specimen linear reciprocating motion quick-change assembly below it; the in-situ observation system is installed on the side of the support frame and aligned with the bottom of the loading assembly; the in-situ observation system and the loading assembly are electrically connected to the data acquisition and control system respectively.

2. A control valve seal pair local friction simulation test machine according to claim 1, characterized in that: The lower specimen linear reciprocating motion quick-change assembly includes multiple reciprocating friction platform brackets, a platform frame, two slide rails, two sliders, a mobile platform, two racks and a half gear. The multiple reciprocating friction platform brackets are vertically installed on the top of the box body; the platform frame is installed on the multiple reciprocating friction platform brackets; the two slide rails are correspondingly installed on the two side surfaces of the platform frame; the two sliders are embedded and installed on the two slide rails; the mobile platform is fixed on the two sliders for installing the lower specimen; the two racks are correspondingly fixed on the inner sides of the mobile platform; the half gear is installed on the mounting shaft and is alternately meshed with the two racks.

3. A control valve seal pair local friction simulation test machine according to claim 1, characterized in that: The lower specimen rotating friction quick-change assembly includes a lower specimen tray and a lower specimen pressure plate, wherein the lower specimen tray is mounted on the mounting shaft; the lower specimen tray has a groove for carrying the lower specimen; the lower specimen pressure plate is connected to the lower specimen tray by bolts and pressed onto the lower specimen.

4. A control valve seal pair local friction simulation test machine according to claim 2 or 3, characterized in that: The loading assembly includes a hydraulic cylinder and a ball bearing joint block, wherein the hydraulic cylinder is vertically installed on the support frame; the ball bearing joint block is connected to the telescopic rod of the hydraulic cylinder through a conversion joint; the bottom of the ball bearing joint block has a slot for fixing the upper test piece; the hydraulic cylinder is electrically connected to the data acquisition and control system.

5. A control valve seal pair local friction simulation test machine according to claim 4, characterized in that: It also includes an angle ruler and a retaining ring. The angle ruler is fixed on the top of the support frame, and the angle ruler has an arc groove; the retaining ring is sleeved and fixed on the cylinder body of the hydraulic cylinder; the top of the support frame has a translation hole, and the cylinder body of the hydraulic cylinder passes through the translation hole; the retaining ring is slidably connected to the arc groove through a connecting rod.

6. A control valve seal pair local friction simulation test machine according to claim 2 or 3, characterized in that: The active transmission system includes a servo motor, a first bevel gear, a second bevel gear, a first shaft, a second shaft, a driving wheel, a driven wheel and a synchronous belt. The first bevel gear is installed on the output shaft of the servo motor; the first shaft is vertically installed in the housing through a bearing seat; the second bevel gear is installed on the first shaft and meshed with the first bevel gear; the second shaft is vertically installed in the housing through a bearing seat and is distributed parallel to the first shaft, and the top end of the second shaft is connected to the mounting shaft through the coupling; the driving wheel is installed on the first shaft, the driven wheel is installed on the second shaft, and the driving wheel and the driven wheel are connected through the synchronous belt transmission.

7. A control valve seal pair local friction simulation test machine according to claim 2 or 3, characterized in that: The lower test piece is made of transparent material and is in a semi-circular or boss shape.

8. The control valve seal pair local friction simulation test machine according to claim 1, characterized in that: The in-situ observation system includes a 3D laser profiler and a high-speed industrial camera. The 3D laser profiler and the high-speed industrial camera are electrically connected to a computer through the data acquisition and control system.

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