Intelligent scanning probe

Abstract

The invention discloses an intelligent scanning probe. Comprising a control module, a probe module and a sensing module, the sensing module comprises a parallel leaf spring mechanism and a displacement sensor; a damping device is arranged in the parallel leaf spring mechanism; the displacement sensor is located on one side of the damping device and installed in the parallel leaf spring mechanism. The probe module is mounted on the outer side of the bottom of the parallel leaf spring mechanism, and a speed detector is arranged on the probe module; the control module is connected with the damping device and the speed detector. Parallel displacement is achieved through the leaf spring mechanism, and the displacement sensor records and senses the displacement amount; the damping device suppresses the vibration of the leaf spring mechanism and improves the measurement efficiency, and the control module controls the damping force of the damping device according to different movement speeds or accelerations of the scanning probe collected by the speed detector, so that the damping force is always matched with the movement characteristics of the probe and the dynamic characteristics of the scanning probe are improved.

Description

Technical Field

[0001] The invention relates to the field of measurement technology, in particular to an intelligent scanning probe. Background Art

[0002] The parallel leaf spring mechanism has a simple structure, flexible movement, and low cost. Since it can produce micro-displacement, it is often used in linear displacement situations with parallel motion. Therefore, it has become the preferred structure for micro-displacement devices in scanning probes. However, the defect of this mechanism is that the spring leaf will produce elastic deformation under force, generating a component force, which causes vibration. On the one hand, it affects the dynamic characteristics of the scanning probe. On the other hand, it takes a long time for the entire mechanism to restore balance, thus limiting the application of scanning probes in actual measurements. Summary of the invention

[0003] In view of this, the present application provides an intelligent scanning probe, which overcomes the problem that the existing parallel leaf spring mechanism is prone to vibration during use, affecting the performance of the scanning probe, and improves the dynamic characteristics of the scanning probe by adjusting the resistance of the damping fluid in the damping device. The specific scheme is as follows:

[0004] An intelligent scanning probe comprises: a control module, a probe module and a sensing module;

[0005] The sensing module includes a parallel leaf spring mechanism for realizing parallel displacement of the scanning probe, and a displacement sensor for collecting displacement of the parallel leaf spring mechanism;

[0006] A damping device is provided in the parallel leaf spring mechanism for absorbing or eliminating vibration caused by the parallel leaf spring mechanism when it moves;

[0007] The damping device is installed in the parallel leaf spring mechanism;

[0008] The displacement sensor is located at one side of the damping device, and the displacement sensor is installed in the parallel leaf spring mechanism;

[0009] The probe module is installed on the outside of the bottom of the parallel leaf spring mechanism, the probe module is in contact with the object to be measured, and a speed detector is arranged on the probe module;

[0010] The control module is connected to the damping device and the speed detector respectively. The control module controls the damping force of the damping device according to the different movement speeds or accelerations of the scanning probe collected by the speed detector, so that the damping force always matches the movement characteristics of the probe.

[0011] Preferably, the damping device comprises a damping cylinder and a damping rod;

[0012] The damping cylinder is installed at the center of the inner side of the bottom of the parallel leaf spring mechanism, the damping cylinder is filled with damping fluid, a pressure sensor is arranged on the inner side of the bottom of the damping cylinder, and the damping fluid is a metafluid material;

[0013] One end of the damping rod is connected to the top of the parallel leaf spring mechanism, the other end of the damping rod is a ball head, the ball head is inserted into the damping cylinder, and the damping rod is sealed and connected to the cylinder cover of the damping cylinder;

[0014] The control module is connected to the damping cylinder and the pressure sensor.

[0015] Preferably, the control module includes a damping fluid replenishing unit, a processor and a controller;

[0016] The damping fluid replenishing unit is disposed outside the damping cylinder, the damping fluid replenishing unit is installed in the parallel leaf spring mechanism, and the damping fluid replenishing unit is connected to the damping cylinder;

[0017] The output port of the damping fluid supply unit is provided with a solenoid valve;

[0018] The processor is respectively connected to the speed collector, the pressure sensor and the controller;

[0019] The controller is communicatively connected to the solenoid valve and the damping fluid supply unit respectively.

[0020] Preferably, the damping fluid replenishing unit comprises a damping fluid storage device and a bidirectional pump;

[0021] The damping fluid storage device stores damping fluid;

[0022] The bidirectional pump is connected to the damping fluid storage and the damping cylinder respectively, and the bidirectional pump is connected to the controller.

[0023] Preferably, the parallel leaf spring mechanism comprises at least two leaf springs;

[0024] The two leaf springs are arranged in parallel and are respectively located on two opposite sides of the displacement sensor, and an upper leaf spring seat and a lower leaf spring seat are respectively arranged at both ends of the leaf spring, and the two ends are respectively connected to the upper leaf spring seat and the lower leaf spring seat;

[0025] The displacement sensor is installed below the upper leaf spring seat;

[0026] The two ends of the damping device are respectively connected to the upper leaf spring seat and the lower leaf spring seat.

[0027] Preferably, a connecting assembly is provided at one end of the damping rod connected to the parallel leaf spring mechanism;

[0028] One end of the connecting assembly is connected to the damping rod, and the other end of the connecting assembly is connected to the top of the parallel leaf spring mechanism.

[0029] Preferably, the connection assembly includes a top screw and a mounting adjustment rod;

[0030] One end of the top screw is connected to the damping rod, and the other end of the top screw is connected to the installation adjustment rod;

[0031] One end of the installation adjustment rod facing away from the top screw is connected to the top of the parallel leaf spring mechanism.

[0032] Preferably, a seal is provided between the damping rod and the cylinder head;

[0033] The sealing sleeve is installed on the cylinder head, and the inner and outer sides of the sealing are respectively against the damping rod and the cylinder head;

[0034] The outer dimension of the sealing element gradually increases along a direction facing away from the damping cylinder.

[0035] Preferably, the probe module comprises a fixing seat, a measuring needle seat and a measuring needle which are arranged in sequence from top to bottom;

[0036] The fixing seat is connected to the outer side of the bottom of the parallel leaf spring mechanism;

[0037] A movable connecting piece is provided between the measuring needle seat and the fixing seat, and the movable connecting piece connects the measuring needle seat and the fixing seat respectively;

[0038] The stylus is mounted at the center of the bottom of the stylus holder.

[0039] Preferably, the movable connecting member comprises a magnet and a steel ball group;

[0040] The magnets are respectively installed at the center position of the side of the probe seat opposite to the fixing seat, and the magnets installed on the probe seat and the fixing seat are magnetically connected;

[0041] The steel ball group is provided with a plurality of steel balls, and is respectively provided on the peripheral side of the magnet; the steel ball group includes a first steel ball provided on the fixing seat, and a second steel ball provided on the measuring needle seat;

[0042] The first steel ball is installed on a side of the fixing seat facing the measuring needle seat, and two first steel balls are provided;

[0043] The second steel ball is installed on a side of the probe seat facing the fixed seat, one second steel ball is provided, and the second steel ball is located between two adjacent first steel balls in the same group;

[0044] The second steel balls are respectively in contact with two adjacent first steel balls.

[0045] Compared with the prior art, the beneficial effects of this application are:

[0046] The present application provides the possibility of parallel displacement of the scanning probe by means of the provided parallel leaf spring mechanism, and records / senses the displacement of the scanning probe by means of the provided displacement sensor; the provided damping device suppresses the vibration of the leaf spring mechanism, thereby improving the dynamic characteristics of the scanning probe and saving the time required to restore balance, thereby improving the measurement efficiency;

[0047] The speed or acceleration of the scanning probe movement is obtained through the set speed collector, and the pressure of the damping fluid in the damping cylinder is obtained through the pressure sensor. The processor calculates the theoretical damping force of the damping fluid in the damping cylinder according to the collected speed or acceleration, and compares the theoretical damping force with the obtained pressure of the damping fluid in the damping cylinder, and calculates the difference. The control module controls the bidirectional pump according to the difference to input or output the damping fluid into the damping cylinder, so that the damping force of the damping fluid in the damping cylinder matches the motion characteristics of the probe in real time, thereby maximizing the performance of the scanning probe. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 A front view of a scanning probe for this application;

[0049] Figure 2 A cross-sectional schematic diagram of a scanning probe of the present application;

[0050] Figure 3 This is a schematic diagram of the principle framework of a control module in a scanning probe of the present application.

[0051] In the figure:

[0052] 1. Leaf spring seat; 2. Leaf spring; 3. Damping device; 4. Displacement sensor bracket; 5. Displacement sensor; 6. Fixed seat; 7. Probe seat; 8. Probe; 9. Magnet; 10. Steel ball; 3-1. Damping cylinder; 3-2. Cylinder cover; 3-3. Damping rod; 3-4. Seal; 3-5. Install adjustment rod; 3-6. Nut; 3-7. Top screw. DETAILED DESCRIPTION

[0053] 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.

[0054] See also Figure 1-3, the present invention provides an intelligent scanning probe, comprising: a control module, a probe module and a sensing module;

[0055] The sensing module includes a parallel leaf spring mechanism for scanning the probe to perform parallel displacement, and a displacement sensor 5 for collecting the displacement of the parallel leaf spring mechanism;

[0056] A damping device 3 is provided in the parallel leaf spring mechanism to absorb and eliminate the vibration caused by the parallel leaf spring mechanism when it moves;

[0057] The damping device 3 is installed in the parallel leaf spring mechanism;

[0058] The displacement sensor 5 is located at one side of the damping device 3, and the displacement sensor 5 is installed in the parallel leaf spring mechanism;

[0059] The probe module is installed on the outside of the bottom of the parallel leaf spring mechanism, the probe module is in contact with the object to be measured, and a speed detector is arranged on the probe module;

[0060] The control module is connected to the damping device 3 and the speed detector respectively. The control module adjusts the damping force of the damping device 3 according to the different movement speeds or accelerations of the scanning probe collected by the speed detector, so that the damping force always matches the motion characteristics of the probe.

[0061] The center lines of the damping device 3 and the parallel leaf spring mechanism coincide, and the top and bottom ends of the damping device 3 are respectively connected to the top and bottom of the leaf spring mechanism;

[0062] The displacement sensor 5 is located at one side of the damping device 3 , and the displacement sensor 5 is installed on the top of the parallel leaf spring mechanism.

[0063] The displacement sensor 5 is installed on the top of the inner side of the parallel leaf spring mechanism through the displacement sensor bracket 4. The displacement sensor bracket 4 is located outside the displacement sensor 5. The displacement sensor 5 is installed on the inner side of the bottom of the displacement sensor bracket 4. The displacement sensor bracket 4 is located in the parallel leaf spring mechanism. The top of the displacement sensor bracket 4 is connected to the inner side of the top of the parallel leaf spring mechanism. The bottom of the displacement sensor bracket 4 is set with a gap between it and the bottom of the parallel leaf spring mechanism.

[0064] Further, the damping device 3 includes a damping cylinder 3-1 and a damping rod 3-3;

[0065] The damping cylinder 3-1 is installed at the center of the inner side of the bottom of the parallel leaf spring mechanism. The damping cylinder 3-1 is filled with damping fluid. A pressure sensor is arranged on the inner side of the bottom of the damping cylinder 3-1. The damping fluid is a metafluid material.

[0066] One end of the damping rod 3-3 is connected to the top of the parallel leaf spring mechanism, the other end of the damping rod 3-3 is a ball head, the ball head is inserted into the damping cylinder 3-1, and the damping rod 3-3 is sealed and connected to the cylinder cover of the damping cylinder 3-1;

[0067] The control module is connected to the damping cylinder 3 - 1 and the pressure sensor.

[0068] Further, the control module includes a damping fluid supply unit, a processor and a controller;

[0069] The damping fluid replenishing unit is disposed outside the damping cylinder, the damping fluid replenishing unit is installed in the parallel leaf spring mechanism, and the damping fluid replenishing unit is connected to the damping cylinder;

[0070] The output port of the damping fluid supply unit is provided with a solenoid valve;

[0071] The processor is respectively connected to the speed collector, the pressure sensor and the controller;

[0072] The controller is communicatively connected to the solenoid valve and the damping fluid supply unit respectively.

[0073] Further, the damping fluid replenishing unit includes a damping fluid storage device and a bidirectional pump;

[0074] The damping fluid storage device stores damping fluid;

[0075] The bidirectional pump is connected to the damping fluid storage and the damping cylinder respectively, and the bidirectional pump is connected to the controller.

[0076] Further, the parallel leaf spring mechanism comprises at least two leaf springs 2;

[0077] Two leaf springs 2 are arranged vertically and parallel to each other. Leaf spring seats 1 are respectively arranged at both ends of the two leaf springs 2, that is, an upper leaf spring seat is arranged at the top end, and a lower leaf spring seat is arranged at the bottom end. The top and bottom ends of the two leaf springs 2 are respectively connected with the upper leaf spring seat and the lower leaf spring seat to form a frame structure. The displacement sensor bracket 4 is located in the formed frame structure. The top of the displacement sensor bracket 4 is connected to the upper leaf spring seat, and the bottom of the displacement sensor bracket 4 is arranged with a gap with the lower leaf spring seat.

[0078] The two ends of the damping device 3 are connected to the upper leaf spring seat and the lower leaf spring seat respectively.

[0079] Further, the cylinder cover is installed at the opening of the damping cylinder 3-1, and the damping cylinder 3-1 is installed on the inner side of the bottom part of the parallel leaf spring mechanism (i.e., the upper leaf spring seat);

[0080] A connecting assembly is provided between the damping rod 3-3 and the top of the parallel leaf spring mechanism, one end of the connecting assembly is connected to the

[0081] The damping rod 3-3 is connected, and the other end of the connecting assembly is connected to the top of the parallel leaf spring mechanism (i.e. the top of the lower leaf spring seat).

[0082] Further, the connection assembly includes a top screw 3-7 and a mounting adjustment rod 3-5;

[0083] One end of the top screw 3-7 is connected to the damping rod 3-3, and the other end of the top screw 3-7 is connected to the installation adjustment rod 3-5;

[0084] One end of the installation adjustment rod 3-5 facing away from the top screw is connected to the top of the parallel leaf spring mechanism (i.e., the upper leaf spring seat).

[0085] Furthermore, the sealing connection between the damping rod 3-3 and the cylinder head 3-2 is achieved through a sealing member. The sealing member 3-4 is sleeved on the cylinder head 3-2, and the inner and outer sides of the sealing member 3-4 abut against the damping rod 3-3 and the cylinder head 3-2 respectively.

[0086] Furthermore, the outer dimensions of the seal 3 - 4 gradually increase in the direction away from the damping cylinder.

[0087] Furthermore, the probe module includes a fixing seat 6, a measuring needle seat 7 and a measuring needle 8 which are arranged in sequence from top to bottom;

[0088] The fixing seat 6 is connected to the outer side of the bottom of the parallel leaf spring mechanism;

[0089] A movable connecting piece is provided between the measuring needle seat 7 and the fixing seat 6, and the movable connecting piece connects the measuring needle seat 8 and the fixing seat 6 respectively;

[0090] The measuring needle 8 is movably mounted at the center of the bottom of the measuring needle seat 7 .

[0091] Further, the movable connecting member includes a magnet 9 and a steel ball group 10;

[0092] The magnets 9 are respectively installed at the center of the side of the probe seat opposite to the fixing seat, and the magnets installed on the probe seat and the fixing seat are magnetically connected;

[0093] The steel ball group is provided with a plurality of steel balls, and is respectively provided on the peripheral side of the magnet; the steel ball group includes a first steel ball provided on the fixing seat, and a second steel ball provided on the measuring needle seat;

[0094] The first steel ball is installed on the side of the fixing seat 6 facing the measuring needle seat 7, and two first steel balls are provided;

[0095] The second steel ball is installed on a side of the measuring needle seat facing the fixing seat 6, and one second steel ball is provided, and the second steel ball is located between two adjacent first steel balls in the same group;

[0096] The second steel balls are respectively in contact with two adjacent first steel balls, forming a triangular structure on a vertical plane.

[0097] The magnet comprises a first magnet and a second magnet, wherein the first magnet and the second magnet are respectively mounted at the center of a side opposite to the fixing seat of the measuring needle seat, and a gap is set between the two magnets and they are magnetically connected.

[0098] It should be noted that:

[0099] In one embodiment of the present application, the displacement sensor is located at the rear side of the damping device.

[0100] In one embodiment of the present application, the displacement sensor bracket 4 is a U-shaped structure with an opening facing upward, wherein both ends of the opening of the U-shaped structure are connected to the bottom of the upper leaf spring seat, a gap is set between the bottom of the U-shaped structure and the lower leaf spring seat, and the two leaf springs are just located outside the two side walls of the U-shaped structure. During installation, the center line of the displacement sensor 5 and the center line of the damping device are located on the same plane.

[0101] Install the adjustment rod as an adjustment bolt;

[0102] The damping fluid is damping oil;

[0103] The leaf spring mechanism is a parallel leaf spring mechanism;

[0104] The seal is a sealing membrane

[0105] In the present application, a stylus 8 is installed on the stylus holder 7, and different stylus needles can be replaced according to different measurement requirements. A steel ball 10 and a magnet 9 are provided on the stylus holder 7 and the fixed seat 6. The steel ball 10 is positioned, and the suction force of the magnet combines the stylus holder 7 and the fixed seat 6 into one, thereby realizing anti-collision protection and quick replacement functions.

[0106] In the present application, a group of leaf spring seats 1 formed by the upper leaf spring seat and the lower leaf spring seat and a group of leaf springs 2 (i.e., two leaf springs arranged in parallel) constitute a parallel leaf spring mechanism as a displacement generating mechanism, the displacement sensor 5 records the induced displacement, and the damping device 3 suppresses the vibration of the leaf spring mechanism, thereby improving the dynamic characteristics of the scanning probe.

[0107] In the present application, the damping device 3 is composed of a damping cylinder 3-1, a cylinder cover 3-2 arranged at the lever mouth of the damping cylinder 3-1, a damping rod 3-3, a seal 3-4, and an installation adjustment rod 3-5. The damping cylinder 3-1 is fixed on the lower leaf spring seat, and the installation adjustment rod 3-5 is fixed to the upper leaf spring seat by a nut 3-6. The top screw 3-7 connects the damping rod 3-3 and the installation adjustment rod 3-5 as a whole, thereby realizing the installation of the damping device 3 in the parallel leaf spring mechanism and applying it to the scanning probe. During use, when the parallel leaf spring mechanism produces a micro-displacement, the damping rod 3-3 also produces a displacement in the damping cylinder 3-1. The damping cylinder 3-1 is filled with damping oil, and the damping oil has a certain viscosity. When resetting, the damping rod 3-3 is reset in the damping cylinder 3-1 at the same time. The tiny friction between the damping rod ball head (the end of the damping rod extending into the damping cylinder) and the damping oil limits the vibration of the parallel leaf spring mechanism, allowing the parallel leaf spring mechanism to quickly reset and balance, thereby improving measurement efficiency. At the same time, the application of the damping device avoids the occurrence of vibration and improves the dynamic characteristics of the scanning probe. The application of the damping device in this application does not affect the flexibility of the parallel leaf springs, does not increase external force, and improves the dynamic characteristics of the scanning probe without changing the original characteristics and performance of the scanning probe.

[0108] In the present application, when the damping fluid is a new material Metafluid (i.e., a metafluid material), the performance of the metafluid material depends on the structure. It is composed of tens of thousands of highly variable spherical capsules filled with air. When the pressure inside increases to exceed a threshold, these capsules will collapse to form a lens-shaped hemisphere. When the pressure disappears, the capsule will rebound to a spherical shape. This will cause a significant change in the volume of the metafluid, resulting in a change in the damping force of the group fluid. In the present application, according to the speed or acceleration of the scanning probe monitored in real time, the total amount of the damping cylinder in the damping cylinder is adjusted in real time to achieve the adjustment of the number of capsules in the damping fluid, so that the damping fluid in the damping cylinder provides a damping force that matches the movement of the scanning probe.

Claims

1. An intelligent scanning probe, characterized in that: include: Control module, probe module and sensor module; The sensing module includes a parallel leaf spring mechanism for realizing parallel displacement of the scanning probe, and a displacement sensor for collecting the displacement of the scanning probe; A damping device is provided in the parallel leaf spring mechanism for absorbing or eliminating vibration caused by the parallel leaf spring mechanism during movement; The damping device is installed in the parallel leaf spring mechanism; The displacement sensor is located at one side of the damping device, and the displacement sensor is installed in the parallel leaf spring mechanism; The probe module is installed on the outside of the bottom of the parallel leaf spring mechanism, the probe module is in contact with the object to be measured, and a speed detector is arranged on the probe module; The control module is connected to the damping device and the speed detector respectively. The control module adjusts the damping force of the damping device according to the movement speed or acceleration of the scanning probe collected by the speed detector, so that the damping force always matches the movement characteristics of the probe.

2. The intelligent scanning probe according to claim 1, characterized in that: The damping device comprises a damping cylinder and a damping rod; The damping cylinder is installed at the center of the inner side of the bottom of the parallel leaf spring mechanism, the damping cylinder is filled with damping fluid, a pressure sensor is arranged on the inner side of the bottom of the damping cylinder, and the damping fluid is a metafluid material; One end of the damping rod is connected to the top of the parallel leaf spring mechanism, the other end of the damping rod is a ball head, the ball head is inserted into the damping cylinder, and the damping rod is sealed and connected to the cylinder cover of the damping cylinder; The control module is connected to the damping cylinder and the pressure sensor.

3. The intelligent scanning probe according to claim 2, characterized in that: The control module includes a damping fluid supply unit, a processor and a controller; The damping fluid replenishing unit is disposed outside the damping cylinder, the damping fluid replenishing unit is installed in the parallel leaf spring mechanism, and the damping fluid replenishing unit is connected to the damping cylinder; The output port of the damping fluid supply unit is provided with a solenoid valve; The processor is respectively connected to the speed collector, the pressure sensor and the controller; The controller is communicatively connected to the solenoid valve and the damping fluid supply unit respectively.

4. The intelligent scanning probe according to claim 3, characterized in that: The damping fluid replenishing unit includes a damping fluid storage device and a bidirectional pump; The damping fluid storage device stores damping fluid; The bidirectional pump is connected to the damping fluid storage and the damping cylinder respectively, and the bidirectional pump is connected to the controller.

5. The intelligent scanning probe according to claim 2, characterized in that: The parallel leaf spring mechanism comprises at least two leaf springs; The two leaf springs are arranged in parallel and are respectively located on two opposite sides of the displacement sensor, and an upper leaf spring seat and a lower leaf spring seat are respectively arranged at both ends of the leaf spring, and the two ends are respectively connected to the upper leaf spring seat and the lower leaf spring seat; The displacement sensor is installed below the upper leaf spring seat; The two ends of the damping device are respectively connected to the upper leaf spring seat and the lower leaf spring seat.

6. The intelligent scanning probe according to claim 1, characterized in that: One end of the damping rod connected to the parallel leaf spring mechanism is provided with a connecting assembly; One end of the connecting assembly is connected to the damping rod, and the other end of the connecting assembly is connected to the top of the parallel leaf spring mechanism.

7. The intelligent scanning probe according to claim 6, characterized in that: The connecting assembly includes a top screw and an installation adjustment rod; One end of the top screw is connected to the damping rod, and the other end of the top screw is connected to the installation adjustment rod; One end of the installation adjustment rod facing away from the top screw is connected to the top of the parallel leaf spring mechanism.

8. The intelligent scanning probe according to claim 2, characterized in that: A sealing member is provided between the damping rod and the cylinder head; The sealing sleeve is installed on the cylinder head, and the inner and outer sides of the sealing are respectively against the damping rod and the cylinder head; The outer dimension of the sealing element gradually increases along the direction facing away from the damping cylinder.

9. The intelligent scanning probe according to claim 1, characterized in that: The probe module comprises a fixing seat, a measuring needle seat and a measuring needle which are arranged in sequence from top to bottom; The fixing seat is connected to the outer side of the bottom of the parallel leaf spring mechanism; A movable connecting piece is provided between the measuring needle seat and the fixing seat, and the movable connecting piece connects the measuring needle seat and the fixing seat respectively; The stylus is mounted at the center of the bottom of the stylus holder.

10. The intelligent scanning probe according to claim 8, characterized in that: The movable connecting member includes a magnet and a steel ball group; The magnets are respectively installed at the center position of the side opposite to the fixing seat of the measuring needle seat, and the magnets installed on the measuring needle seat and the fixing seat are magnetically connected; The steel ball group is provided with a plurality of steel balls, and is respectively provided on the peripheral side of the magnet; the steel ball group includes a first steel ball provided on the fixing seat, and a second steel ball provided on the measuring needle seat; The first steel ball is installed on a side of the fixing seat facing the measuring needle seat, and two first steel balls are provided; The second steel ball is installed on a side of the probe seat facing the fixed seat, one second steel ball is provided, and the second steel ball is located between two adjacent first steel balls in the same group; The second steel balls are respectively in contact with two adjacent first steel balls.

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