Hardness measuring device for titanium alloy seamless pipe

Abstract

The present application relates to the technical field of metal pipe detection, and discloses a hardness measuring device for titanium alloy seamless pipes, which comprises a host terminal, a hardness testing probe in communication connection with the host terminal, and a bearing box for placing the host terminal, wherein the side of the bearing box away from the host terminal is provided with a bearing frame, a sliding block is arranged in the bearing frame in a vertical direction, the side of the sliding block and the bottom horizontal section of the bearing frame opposite to each other is respectively provided with a clamping block, a T-shaped screw rod penetrates through and is in threaded connection with the top horizontal section of the bearing frame, a lifting seat is rotatably installed at the bottom end of the T-shaped screw rod, a limiting column is arranged at the top end of the lifting seat, and the limiting column is in penetrating and sliding connection with the top horizontal section of the bearing frame. The present application realizes fast and stable clamping of the titanium alloy seamless pipes, realizes accurate feedback of the loading state, and improves the accuracy of the test and the operation convenience.

Description

Technical Field

[0001] This invention relates to the field of metal pipe testing technology, and more specifically to a hardness measuring device for seamless titanium alloy pipes. Background Technology

[0002] In aerospace, petrochemical, and marine engineering fields, seamless titanium alloy tubes are widely used due to their excellent specific strength, corrosion resistance, and high-temperature resistance. The hardness of the tube is one of the important indicators for measuring its mechanical properties, directly affecting its wear resistance, fatigue strength, and service life during actual service. Therefore, hardness testing is an indispensable process in the production and acceptance of seamless titanium alloy tubes. Currently, the hardness testing of seamless titanium alloy tubes mainly uses portable hardness testers for on-site testing.

[0003] The existing portable titanium alloy seamless tube hardness testing devices mainly have the following technical problems: 1. Insufficient pipe clamping stability affects measurement accuracy: Existing devices lack an effective pipe clamping structure. During testing, operators usually rely on manually pressing the pipe or using simple supports. The pipe is prone to shaking or displacement during the test, causing the contact position between the indenter and the pipe surface to shift, affecting the accuracy and repeatability of hardness measurement.

[0004] 2. The test force application depends on manual feel, resulting in poor consistency: Operators rely on feel to control the contact force between the pressure head and the pipe surface. Differences in force applied by different operators and fluctuations in force applied by the same operator in different operations will lead to inconsistent test forces, making it difficult to guarantee the stability and repeatability of measurement results.

[0005] 3. Relying on auditory judgment to determine whether the pressure head is in place is not suitable for high-noise workshop environments: In the traditional method, operators judge whether the pressure head is in place with the pipe surface by listening to the sound. However, in actual testing environments such as production workshops, the noise of equipment operation and environmental background noise is large, and auditory judgment is easily interfered with, resulting in inaccurate application of test force and directly affecting the reliability of hardness measurement results. Summary of the Invention

[0006] To address the aforementioned problems in the prior art, this invention provides a hardness measuring device for seamless titanium alloy tubes, which can solve the problems mentioned in the background art.

[0007] The objective of this invention can be achieved through the following technical solutions: A hardness measuring device for seamless titanium alloy tubing includes: The system comprises a host terminal, a hardness testing probe communicatively connected to the host terminal, and a carrier box for placing the host terminal. A support frame is located on the side of the carrier box away from the host terminal. A slider is slidably mounted vertically within the support frame. Clamping blocks are respectively located on opposite sides of the slider and the bottom horizontal section of the support frame. A T-shaped lead screw is threaded through and connected to the top horizontal section of the support frame. A lifting seat is rotatably mounted at the bottom end of the T-shaped lead screw. A limit post is located at the top of the lifting seat, and the limit post is slidably connected to the top horizontal section of the support frame. A locking mechanism is located at the top of the lifting seat for fixing the hardness testing probe. A driving mechanism is used to drive the slider to move up and down.

[0008] Preferably, a data cable is provided between the host terminal and the hardness test probe. One end of the data cable is connected to the communication connector of the hardness test probe, and the other end is connected to the communication interface of the core control module in the host terminal.

[0009] Preferably, the top of the carrier box and the side near the host terminal are open, and elastic pads are provided on the inner walls of the opposing sides of the carrier box. The distance between the two elastic pads matches the width of the host terminal. The bottom wall of the carrier box is provided with a mounting base that matches the bottom of the host terminal.

[0010] Preferably, the clamping block is columnar, and an obtuse-angled groove is formed on the end face of one end of the column. The groove wall abuts against the outer wall of the steel pipe to provide support and limit when the steel pipe is clamped.

[0011] Preferably, the locking mechanism includes two symmetrically arranged arc-shaped blocks, the sidewalls of which are threaded and connected to a locking element for fixing the hardness test probe.

[0012] Preferably, the drive mechanism includes a lifting screw, which is rotatably mounted in a support frame. The support frame is threadedly connected to the slider. A servo motor is provided at the top of the support frame, and the output shaft of the servo motor is fixedly connected to the end of the lifting screw shaft via a coupling.

[0013] Preferably, the hardness test probe includes a tube shell, a cylindrical shell threaded to the tube shell, and a cover. A base is slidably disposed inside the tube shell, and a vibration rod is fixedly connected to the bottom end of the base. A force-applying structure is provided between the vibration rod and the tube shell. Two piezoelectric crystals are disposed on the side wall of the vibration rod. An excitation coil is disposed on the inner wall of the tube shell. A light strip is disposed on the outer wall of the tube shell. A wire-passing groove is provided on the outer wall of the annular limiting seat for passing the light strip wire. A normally open switch is disposed inside the cover, with a gap between it and the base.

[0014] Preferably, the inner wall of the tube shell is provided with an annular limiting seat, and the outer wall of the base is provided with multiple sliding grooves, and the base is slidably connected to the annular limiting seat through the sliding grooves.

[0015] Preferably, the force-applying structure includes an assembly plate and a loading spring. The side wall of the vibration rod is provided with multiple protrusions, and the bottom end of the assembly plate is provided with multiple assembly grooves. The protrusions are engaged with the assembly grooves. The bottom end of the assembly plate is provided with an X-shaped hole for the protrusions to pass through. The inner wall of the tube shell is provided with an annular stop seat, and the loading spring is disposed between the assembly plate and the annular stop seat.

[0016] Preferably, the normally open switch includes an insulating base, a conductive ring, and an insulating ring arranged coaxially. The insulating base is fixedly mounted on the top wall of the convex horizontal section of the housing cover, and annular grooves are provided on the outer edges of both the top and bottom ends. The conductive ring is fixedly mounted in the annular groove at the top of the insulating base, and the insulating ring slides in conjunction with the annular groove at the bottom end of the insulating base. Two stationary contacts are provided at the bottom end of the conductive ring. A conductive strip is provided at the top end of the insulating ring, and the conductive ring, conductive strip, LED strip, and core control module in the host terminal are electrically connected. Two moving contacts are provided at the top end of the base, with a gap between the moving contacts and the stationary contacts. Two limiting protrusions are provided at the top end of the insulating ring, and the limiting protrusions are slidably connected to the insulating base through it. Multiple limiting springs are provided at the top end of the insulating ring, and multiple mounting holes are provided at the bottom end of the insulating base to match the adjacent limiting springs.

[0017] The beneficial effects of this invention are as follows: 1. By setting up a drive mechanism consisting of a lifting screw, a slider, and a servo motor, the servo motor drives the lifting screw to rotate, causing the slider to slide vertically along the support frame, bringing the two clamping blocks closer together and clamping the seamless titanium alloy tube tightly. Combined with the obtuse-angled grooves on the end faces of the clamping blocks, the groove walls abut against the outer wall of the tube. The resulting technical effects are: rapid and stable clamping of the seamless titanium alloy tube; the obtuse-angled groove structure increases the contact area between the clamping blocks and the tube, preventing slippage or surface damage during clamping; solving the problem of insufficient stability and easy shaking leading to measurement deviations when manually pressing the tube; and improving the positioning stability of the tube during testing.

[0018] 2. By setting up a lifting and adjusting structure consisting of a T-shaped lead screw, a lifting seat, and a limiting column, the operator rotates the T-shaped lead screw to drive the lifting seat to move downward along the guide of the limiting column. The position of the hardness test probe is adjusted so that the diamond indenter at the bottom of the vibrating rod comes into contact with the surface of the pipe. With the help of the loading spring, it is gradually compressed during the contact process. When the deformation of the loading spring reaches the preset value, the light strip is energized to indicate to the operator to stop rotating the T-shaped lead screw. The technical effect is that it realizes the precise setting of the test force between the diamond indenter and the surface of the pipe, breaking through the traditional method of relying on manual sound to judge whether the indenter is in place. The visual feedback of the light strip replaces the auditory judgment, effectively adapting to the high-noise environment of the workshop, avoiding the problem of damage to the surface of the pipe due to excessive test force or inaccurate measurement due to insufficient test force, and ensuring the consistency and reliability of the test results.

[0019] 3. By setting up a normally open switch consisting of a base, stationary contact, moving contact, insulating base, conductive ring, insulating ring, and conductive strip, the base moves upward during the compression of the loading spring. When the deformation of the loading spring reaches the preset value, the moving contact contacts the stationary contact to close the switch, and the light strip is energized and illuminated. When the moving contact separates from the stationary contact, the light strip goes out. The technical effect is: accurate feedback of the loading status is achieved, allowing operators to intuitively judge whether the diamond indenter has applied the preset test force. Visual signal indication replaces traditional auditory judgment, effectively solving the problem of inaccurate or unclear hearing in noisy workshop environments, avoiding measurement errors caused by test force deviation, and improving the accuracy and ease of operation of the test. Attached Figure Description

[0020] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0021] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a structural diagram of the mounting box in this invention; Figure 3 This is an installation structure diagram of the support frame, slider, clamping block, T-shaped lead screw and lifting seat in this invention; Figure 4 This is a diagram showing the installation structure of the drive mechanism in this invention; Figure 5 This is a structural diagram of the locking mechanism in this invention. Figure 6 This is a diagram showing the installation structure of the hardness testing probe in this invention; Figure 7 This is a cross-sectional view of the hardness testing probe in this invention; Figure 8 This is a diagram showing the installation structure of the tube shell in this invention; Figure 9This is a structural diagram of the installation of the base, vibrating rod, and assembly plate in this invention; Figure 10 This is a cross-sectional view of the normally open switch in this invention; Figure 11 This is an exploded view of the normally open switch in this invention.

[0022] Explanation of reference numerals in the attached figures: 1. Main unit terminal; 2. Hardness test probe; 3. Carrier box; 4. Carrier frame; 5. Slider; 6. Clamping block; 7. T-shaped lead screw; 8. Lifting seat; 9. Limiting post; 21. Tube shell; 211. Ring-type limit seat; 212. Wire groove; 213. Ring-type stop seat; 22. Cylindrical shell; 23. Shell cover; 24. Base; 241. Slide groove; 25. Vibration rod; 251. Protrusion; 252. Assembly plate; 253. Loading spring; 26. Piezoelectric crystal; 27. Excitation coil; 28. Light strip; 29. ​​Normally open switch; 291. Insulating base; 292. Conductive ring; 293. Stationary contact; 294. Conductive strip; 295. Moving contact; 296. Insulating ring; 297. Limiting protrusion; 298. Limiting spring; 31. Mounting base; 32. Elastic pad; 41. Lead screw; 42. Servo motor; 81. Arc-shaped block; 82. Locking component. Detailed Implementation

[0023] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the specific implementation methods, structures, features, and effects of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and preferred embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] In the description of this application, it should be understood that the orientation or positional relationship indicated by terms such as "inner" and "outer" are based on the orientation or position shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or a specific orientational structure and operation, and therefore should not be construed as a limitation of this application.

[0025] Example 1: Reference Figures 1-11 The present invention discloses a hardness measuring device for seamless titanium alloy tubes, comprising: To achieve communication connectivity and stable placement of all components, this embodiment includes: a host terminal 1, a hardness testing probe 2 communicating with the host terminal 1, and a carrier box 3 for placing the host terminal 1. A data cable is provided between the host terminal 1 and the hardness testing probe 2. One end of the data cable is connected to the communication connector of the hardness testing probe 2, and the other end is connected to the communication interface of the core control module inside the host terminal 1. The top and the side of the carrier box 3 closest to the host terminal 1 are open. Elastic pads 32 are provided on the inner walls of the opposing sides of the carrier box 3. The spacing between the two elastic pads 32 matches the width of the host terminal 1. A mounting base 31 is provided on the bottom wall of the carrier box 3, which is connected to the host terminal 1. The bottom of the host terminal 1 is matched, and a support frame 4 is provided on the side of the support box 3 away from the host terminal 1. A slider 5 is slidably arranged vertically inside the support frame 4. Clamping blocks 6 are respectively provided on the opposite side of the bottom horizontal section of the slider 5 and the support frame 4. The clamping blocks 6 are columnar, and an obtuse-angled groove is opened on the end face of one end of the column. The groove wall abuts against the outer wall of the titanium alloy seamless tube, which is used to provide support and limit when the titanium alloy seamless tube is clamped. A T-shaped screw 7 is threaded through and connected to the top horizontal section of the support frame 4. A lifting seat 8 is rotatably installed at the bottom end of the T-shaped screw 7. A limit post 9 is provided at the top of the lifting seat 8. The limit post 9 is slidably connected to the top horizontal section of the support frame 4. In order to achieve rapid locking and fixing of the hardness test probe 2, in this embodiment: a locking mechanism is provided at the top of the lifting seat 8 to fix the hardness test probe 2. The locking mechanism includes two symmetrically arranged arc-shaped blocks 81. A locking element 82 is threaded through and connected to the side wall of the arc-shaped blocks 81 to fix the hardness test probe 2. In order to achieve smooth lifting and lowering of the slider 5 along the support frame 4, in this embodiment: a driving mechanism is used to drive the slider 5 to lift and lower. The driving mechanism includes a lifting screw 41, which is rotatably installed in the support frame 4. The support frame 4 is threadedly connected to the slider 5. A servo motor 42 is provided at the top of the support frame 4. The output shaft of the servo motor 42 is fixedly connected to the shaft end of the lifting screw 41 through a coupling.To achieve electromagnetic vibration, piezoelectric detection, and operational status indication of the hardness testing probe 2, in this embodiment: the hardness testing probe 2 includes a tube shell 21, a cylindrical shell 22 threadedly connected to the tube shell 21, and a cover 23. A base 24 is slidably disposed inside the tube shell 21, and an annular limiting seat 211 is provided on the inner wall of the tube shell 21. Multiple sliding grooves 241 are provided on the outer wall of the base 24. The base 24 is slidably connected to the annular limiting seat 211 through the sliding grooves 241. A vibration rod 25 is fixedly connected to the bottom end of the base 24. A force-applying structure is provided between the vibration rod 25 and the tube shell 21. The force-applying structure includes an assembly... The mounting plate 252 and loading spring 253 are provided. Multiple protrusions 251 are provided on the side wall of the vibrating rod 25. Multiple mounting grooves are provided at the bottom end of the mounting plate 252, with the protrusions 251 engaging with the mounting grooves. An X-shaped hole is provided at the bottom end of the mounting plate 252 for the protrusions 251 to pass through. An annular stop seat 213 is provided on the inner wall of the tube shell 21. The loading spring 253 is positioned between the mounting plate 252 and the annular stop seat 213. Two piezoelectric crystals 26 are provided on the side wall of the vibrating rod 25. An excitation coil 27 is provided on the inner wall of the tube shell 21. A light strip 28 is provided on the outer wall of the tube shell 21. An annular limit seat 211 is located outside... The wall is provided with a wire groove 212 for threading the wire of the light strip 28. A normally open switch 29 is provided inside the cover 23, with a gap between it and the base 24. The normally open switch 29 includes an insulating base 291, a conductive ring 292, and an insulating ring 296 arranged coaxially. The insulating base 291 is fixedly installed on the top wall of the convex horizontal section of the cover 23, and both the top and bottom outer edges are provided with annular grooves. The conductive ring 292 is fixedly installed in the annular groove at the top of the insulating base 291. The insulating ring 296 slides in fit with the annular groove at the bottom of the insulating base 291. Two stationary contacts 293 are provided at the bottom of the conductive ring 292. The top of the insulating ring 296 is provided with a conductive strip 294, and the conductive ring 292, conductive strip 294, light strip 28 and the core control module in the host terminal 1 are electrically connected. The top of the base 24 is provided with two moving contacts 295, and there is a gap between the moving contacts 295 and the stationary contacts 293. The top of the insulating ring 296 is provided with two limiting protrusions 297, and the limiting protrusions 297 are connected to the insulating seat 291 through and slidingly. The top of the insulating ring 296 is provided with multiple limiting springs 298, and the bottom of the insulating seat 291 is provided with multiple mounting holes that match the adjacent limiting springs 298.

[0026] The working principle and usage process of this invention are as follows: Before testing, the operator places the seamless titanium alloy tube on the clamping block 6 at the bottom horizontal section of the support frame 4, with the outer wall of the tube abutting against the obtuse-angled groove wall of the clamping block 6 to achieve initial positioning. The servo motor 42 is started, driving the lifting screw 41 to rotate, causing the slider 5 to slide vertically along the support frame 4, bringing the two clamping blocks 6 closer together and clamping the tube securely. Subsequently, the operator rotates the T-shaped screw 7, driving the lifting seat 8 to move downwards along the guide of the limiting post 9, adjusting the position of the hardness test probe 2 so that the diamond indenter at the bottom of the vibration rod 25 abuts against the surface of the tube. During this process, the loading spring 253 is gradually compressed. When the deformation of the loading spring 253 reaches the preset value, the base 24 moves upward to the set position under the drive of the vibrating rod 25. The moving contact 295 contacts the stationary contact 293, closing the normally open switch 29. The light strip 28 is energized and illuminated, indicating to the operator that the loading spring 253 has reached the preset deformation and the diamond indenter has applied the preset test force. At this time, the rotation of the T-shaped lead screw 7 stops, completing the loading setting. During the test, the excitation coil 27 is energized to generate an alternating magnetic field, driving the vibrating rod 25 to generate high-frequency vibration. The vibration of the vibrating rod 25 is transmitted to the diamond indenter through the loading spring 253 and acts on the surface of the pipe. The piezoelectric crystal 26 detects the vibration response signal of the vibrating rod 25 in real time and transmits the signal to the core control module in the host terminal 1 via the data line. The host terminal 1 processes and analyzes the signal to obtain the hardness value of the pipe surface. The insulating base 291, conductive ring 292 and insulating ring 296 constitute the main structure of the switch. The limiting spring 298 and limiting protrusion 297 ensure that the insulating ring 296 is reliably reset when the base 24 moves, thus ensuring the reliable switching on and off of the switch.

[0027] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A hardness measuring device for seamless titanium alloy tubes, characterized in that, include: The host terminal (1), the hardness test probe (2) which is connected to the host terminal (1) in communication, and the carrier box (3) for placing the host terminal (1) are provided. The carrier box (3) is provided with a carrier frame (4) on the side away from the host terminal (1). A slider (5) is slidably provided in the vertical direction inside the carrier frame (4). Clamping blocks (6) are respectively provided on the side of the bottom horizontal section of the slider (5) and the carrier frame (4) facing each other. A T-shaped screw (7) is threaded through and threadedly connected to the top horizontal section of the carrier frame (4). A lifting seat (8) is rotatably installed at the bottom end of the T-shaped screw (7). A limit post (9) is provided at the top of the lifting seat (8). The limit post (9) is slidably connected to the top horizontal section of the carrier frame (4). A locking mechanism is provided at the top of the lifting seat (8) for fixing the hardness test probe (2). A driving mechanism is used to drive the slider (5) to rise and fall.

2. The hardness measuring device for seamless titanium alloy tubes according to claim 1, characterized in that, A data line is provided between the host terminal (1) and the hardness test probe (2). One end of the data line is connected to the communication connector of the hardness test probe (2), and the other end is connected to the communication interface of the core control module in the host terminal (1).

3. The hardness measuring device for seamless titanium alloy tubes according to claim 1, characterized in that, The top of the carrier box (3) and the side near the host terminal (1) are open. The inner walls of the opposing sides of the carrier box (3) are provided with elastic pads (32). The distance between the two elastic pads (32) matches the width of the host terminal (1). The bottom wall of the carrier box (3) is provided with a mounting base (31) that matches the bottom of the host terminal (1).

4. The hardness measuring device for seamless titanium alloy tubes according to claim 1, characterized in that, The clamping block (6) is columnar, and an obtuse-angled groove is provided on the end face of one end of the column. The groove wall of the obtuse-angled groove abuts against the outer wall of the steel pipe, which is used to provide support and limit when the steel pipe is clamped.

5. The hardness measuring device for seamless titanium alloy tubes according to claim 1, characterized in that, The locking mechanism includes two symmetrically arranged arc-shaped blocks (81), the sidewalls of which are threaded and connected to a locking element (82) for fixing the hardness test probe (2).

6. The hardness measuring device for seamless titanium alloy tubes according to claim 1, characterized in that, The drive mechanism includes a lifting screw (41), which is rotatably installed in the support frame (4). The support frame (4) is threadedly connected to the slider (5). A servo motor (42) is provided at the top of the support frame (4). The output shaft of the servo motor (42) is fixedly connected to the shaft end of the lifting screw (41) through a coupling.

7. The hardness measuring device for seamless titanium alloy tubes according to claim 1, characterized in that, The hardness test probe (2) includes a tube shell (21), a cylindrical shell (22) threaded to the tube shell (21), and a cover (23). A base (24) is slidably disposed inside the tube shell (21). A vibration rod (25) is fixedly connected to the bottom end of the base (24). A force-applying structure is provided between the vibration rod (25) and the tube shell (21). Two piezoelectric crystals (26) are provided on the side wall of the vibration rod (25). An excitation coil (27) is provided on the inner wall of the tube shell (21). A light strip (28) is provided on the outer wall of the tube shell (21). A wire groove (212) is provided on the outer wall of the ring-type limiting seat (211) for threading the wire of the light strip (28). A normally open switch (29) is provided inside the cover (23), with a gap between it and the base (24).

8. The hardness measuring device for seamless titanium alloy tubes according to claim 7, characterized in that, The inner wall of the tube shell (21) is provided with an annular limiting seat (211), and the outer wall of the base (24) is provided with multiple sliding grooves (241). The base (24) is slidably connected to the annular limiting seat (211) through the sliding grooves (241).

9. The hardness measuring device for seamless titanium alloy tubes according to claim 7, characterized in that, The force-applying structure includes an assembly plate (252) and a loading spring (253). The vibrating rod (25) has multiple protrusions (251) on its side wall. The assembly plate (252) has multiple assembly grooves at its bottom end. The protrusions (251) engage with the assembly grooves. The assembly plate (252) has an X-shaped hole at its bottom end for the protrusions (251) to pass through. The inner wall of the tube shell (21) has an annular stop seat (213). The loading spring (253) is located between the assembly plate (252) and the annular stop seat (213).

10. The hardness measuring device for seamless titanium alloy tubes according to claim 7, characterized in that, The normally open switch (29) includes an insulating base (291), a conductive ring (292), and an insulating ring (296) arranged coaxially. The insulating base (291) is fixedly disposed on the top wall of the convex horizontal section of the cover (23), and both the top and bottom outer edges are provided with annular grooves. The conductive ring (292) is fixedly disposed in the annular groove at the top of the insulating base (291). The insulating ring (296) is slidably engaged with the annular groove at the bottom of the insulating base (291). The bottom end of the conductive ring (292) is provided with two stationary contacts (293). The top end of the insulating ring (296) is provided with a conductive strip (294), and the conductive ring (296) is... 2) The conductive strip (294), the light strip (28) and the core control module inside the host terminal (1) are electrically connected. The base (24) has two moving contacts (295) at the top. There is a gap between the moving contacts (295) and the stationary contacts (293). The insulating ring (296) has two limiting protrusions (297) at the top. The limiting protrusions (297) are connected to the insulating seat (291) through and slidingly. The insulating ring (296) has multiple limiting springs (298) at the top. The insulating seat (291) has multiple mounting holes at the bottom, which match the adjacent limiting springs (298).

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