High-temperature SHPB dynamic compression test device

Abstract

The invention discloses a high-temperature SHPB (split Hopkinson pressure bar) dynamic compression test device, which is characterized in that a gas gun and a heating furnace are fixed on a rack, an incident bar and a transmission bar are arranged on two sides of the heating furnace, strain gauges are adhered to the incident bar and the transmission bar, a sample is arranged in the heating furnace, and a plurality of fasteners are divided into two groups, are fixed on the rack and are arranged on two sides of the heating furnace; the incident rod and the transmission rod are respectively fixed on each group of fasteners, the two locking blocks are respectively fixed on the incident rod and the transmission rod, the two driving pieces are connected to the rack in a sliding manner, the driving pieces can horizontally rotate, driving blocks are arranged on the driving pieces, and the two driving pieces are driven by an electric driving mechanism arranged on the rack to linearly displace. In the linear displacement process of the driving piece, the driving block abuts against the corresponding locking block to drive the incident rod and the transmission rod to linearly move towards the heating furnace, and the driving piece horizontally rotates by 180 degrees so that the incident rod and the transmission rod can linearly move away from the heating furnace. According to the invention, the problem that the test result is affected due to overlong test time caused by a manual push rod in a traditional device is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to a high-temperature SHPB dynamic compression test device, belonging to the field of material sample testing. BACKGROUND

[0002] The high-temperature Hopkinson pressure bar (SHPB) test is designed to study the dynamic mechanical properties of materials at high temperature and high strain rate. By measuring the propagation of stress waves in the bar, the stress-strain relationship, dynamic strength and failure mode of materials under high-temperature impact coupling are analyzed. The basic principle is to measure the dynamic response of the material by using the propagation of stress waves in the elastic bar. The experimental device mainly includes a gas gun, a heating furnace, an incident bar (close to the gas gun) and a transmission bar. When the bullet (i.e. the launch bar) fired by the gas gun hits the incident bar, a stress wave is generated in the incident bar. According to the propagation theory of stress waves at the interface between different media, part of the wave will pass through the sample into the transmission bar, and part of the wave will be reflected back to the incident bar. The strain signals of the incident wave, the reflected wave and the transmitted wave are measured by the strain gauges attached to the bar. Combined with the one-dimensional stress wave theory, the stress, strain and strain rate of the sample are calculated. The defects of the existing structure are as follows: Because high temperature will affect the propagation of stress waves in the bar (i.e. the incident bar and the transmission bar), thus affecting the experimental data and experimental results, the longest time of the bar in the high-temperature furnace cannot exceed ten seconds. The traditional high-temperature SHPB device can only be pushed manually, and the pre-preparation work such as pushing the bar and inflating the gas gun far exceeds ten seconds, which not only affects the test results, but also causes the bullet to be triggered or the data acquisition system to be started in time due to the tension of human operation.

[0003] Some devices use an integrated electric actuator scheme to automatically advance the incident bar and the transmission bar. Most of them directly fix the linear free end of the electric actuator to the incident bar and the transmission bar (such as directly fixing the slider of the electric slider unit to the incident bar and the transmission bar, and directly fixing the chain of the cooperation and chain wheel unit to the incident bar and the transmission bar). The defect of this structure is that the incident bar and the transmission bar will rebound after being hit by the high-speed launch bar during the test. This rebound force will directly act on the motor of the electric actuator, which will damage the motor over time. SUMMARY

[0004] The present application is to solve the problems existing in the prior art and provides a high-temperature SHPB dynamic compression test device.

[0005] The technical solution adopted by the present application is: The application discloses a high-temperature SHPB dynamic compression test device which comprises a rack, an incident rod, a transmission rod, a gas gun and a heating furnace, the gas gun and the heating furnace are fixed on the rack, the incident rod and the transmission rod are arranged on the two sides of the heating furnace, the incident rod is close to the side of the gas gun, strain gauges are attached to the incident rod and the transmission rod, the device further comprises fasteners, locking blocks, driving members and a sample, the sample is arranged in the heating furnace, a plurality of fasteners are fixed on the rack and arranged on the two sides of the heating furnace, the incident rod and the transmission rod are fixed on each group of fasteners and can move axially relative to the fasteners, the two locking blocks are fixed on the incident rod and the transmission rod, the two driving members are slidably connected to the rack and can rotate horizontally, driving blocks are arranged on the driving members, the two driving members are driven to move linearly by an electric driving mechanism arranged on the rack, the driving blocks are in contact with the corresponding locking blocks during the linear movement of the driving members, so that the incident rod and the transmission rod are driven to move linearly towards the heating furnace, and the driving members are rotated horizontally by 180 DEG, so that the incident rod and the transmission rod move linearly away from the heating furnace.

[0006] Further, two electric linear guides are fixed on the rack, the linear free ends of the electric linear guides are fixedly connected with the driving members, and the driving members are driven to move linearly on the rack.

[0007] Further, a horizontal rotation structure for driving the driving members to rotate horizontally by 180 DEG is fixed on the electric linear guide, the horizontal rotation structure comprises a servo motor and a rotating disc, the motor shaft of the servo motor is fixed with the rotating disc, and the driving members are fixed on the rotating disc.

[0008] Further, the horizontal rotation structure further comprises a limiting seat and a limiting pin, the limiting seat is fixed on the electric linear guide, the limiting pin is fixed on the rotating disc and rotates with the rotating disc, and two limiting grooves are arranged on the limiting seat and located on the rotating path of the limiting pin.

[0009] Further, a spring buffer is arranged on the rack and located on one side of the transmission rod.

[0010] Further, the driving block can be one-way vertically flipped on the driving member.

[0011] Further, the driving block is a right-angle block which is rotatably connected to the driving member through a rotating shaft, a torsional spring is arranged on the rotating shaft, and the horizontal edge of the driving block is in contact with the driving member under the torsional force of the torsional spring.

[0012] Further, the outer edge of the vertical edge of the driving block is an arc surface structure.

[0013] Further, the fastener comprises an upper seat, a lower seat, three adjusting rods and three rollers, the upper seat and the lower seat are fixedly connected by a quick release structure, the three adjusting rods are arranged at equal angles and connected to the upper seat and the lower seat, and the rollers are rotatably connected to the ends of the adjusting rods, the positions of the adjusting rods on the corresponding upper seat and lower seat are adjustable, so as to adjust the relative distance between the three rollers.

[0014] Further, the quick release structure comprises two symmetrically arranged inserts provided on the upper seat, a clamping groove provided on each of the inserts, an insert slot, a lock and a spring provided on the lower seat, the lock is rotatably connected to the lower seat and has one end extending into the insert slot, the spring is arranged in the insert slot and has one end abutting against the lock and the other end abutting against the inner wall of the insert slot, the inserts are inserted into the insert slots, and the corresponding end of the lock abuts against the clamping groove under the elastic force of the spring.

[0015] Further, the heating furnace comprises an outer thermal insulation cover, an electric heating pipe and an inner thermal insulation pipe, the electric heating pipe and the inner thermal insulation pipe are coaxially arranged, the inner thermal insulation pipe is arranged in the electric heating pipe, the electric heating pipe is arranged in the outer thermal insulation cover, and the sample is arranged in the inner thermal insulation pipe.

[0016] Further, the inner wall of the inner thermal insulation pipe is provided with a limiting groove in the axial direction, and a limiting rib is arranged on the outer wall of the sample, and the limiting rib is slidably arranged in the limiting groove.

[0017] The present application has the following advantages: (1) The present application solves the problem of long test time caused by manual push rod in the traditional device, which affects the test results.

[0018] (2) In view of the problem that the motor of the electric actuator is damaged by the rebound force of the incident rod and the transmission rod after being impacted by the high-speed impact of the emission rod in the traditional device, the driving part of the present application can rotate horizontally, the incident rod and the transmission rod are separated and away from the electric drive mechanism after being impacted, which effectively avoids the damage of the electric drive mechanism and prolongs the service life of the equipment.

[0019] (3) In the test process, the incident rod and the transmission rod will produce a rebound force after being impacted by the high-speed impact of the emission rod. In the traditional device, this rebound force will directly act on the driving mechanism, which may cause damage to the driving mechanism. The driving block of the present application can be vertically flipped in one direction, and when the locking block hits the driving block, the driving block can be flipped, thereby effectively removing the force of the locking block hitting the driving block, reducing the impact on the electric linear guide rail and other driving mechanisms, and protecting the driving mechanism from damage. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The structure diagram of the present application.

[0021] Figure 2 The assembly diagram of the transmission rod and the heating furnace on the rack.

[0022] Figure 3The assembly view of the locking block on the transmission rod and the driving member below it.

[0023] Figure 4 The Figure 3 The state view after the horizontal 180° rotation of the middle driving member.

[0024] Figure 5 The schematic view of the 180° rotation structure of the driving member.

[0025] Figure 6 The structural view of the fastener.

[0026] Figure 7 The detachable assembly view of the fastener.

[0027] Figure 8 The exploded view of the heating furnace.

[0028] Figure 9 The structural view of the sample.

[0029] The following are the components mentioned in the text and their numbers: Among them: 1, rack; 10, spring buffer; 11, electric linear guide; 12, servo motor; 13, turntable; 14, limit seat; 15, limit pin; 16, mounting seat; 2, incident rod; 3, transmission rod; 4, air gun; 5, heating furnace; 51, outer insulation cover; 52, electric heating tube; 53, inner insulation tube; 6, fastener; 61, upper seat; 611, plug; 62, lower seat; 621, lock catch; 622, spring; 63, adjusting rod; 64, roller; 7, locking block; 8, driving member; 81, driving block; 82, torsional spring; 9, sample; 91, limiting rib; Figure 2 、 Figure 3 、 Figure 6 and Figure 7 The corresponding letters A, B involved in the middle are the guide numbers of the enlarged view. DETAILED DESCRIPTION

[0030] The application will be further described below in conjunction with the drawings.

[0031] As Figure 1 and Figure 2 , the high-temperature SHPB dynamic compression test device of the application comprises a rack 1, an incident rod 2, a transmission rod 3, an air gun 4, a heating furnace 5, a fastener 6, a locking block 7, a driving member 8, and a sample 9.

[0032] The rack 1 comprises a base and a crossbeam, the crossbeam is fixed on the base, the air gun 4 and the heating furnace 5 are fixed on the crossbeam of the rack 1, the incident rod 2 and the transmission rod 3 are arranged on the two sides of the heating furnace 5, and the incident rod 2 is close to one side of the air gun 4, and strain gauges are attached on the incident rod and the transmission rod for measuring the strain signals of the incident rod and the transmission rod.

[0033] The sample 9 is arranged in the heating furnace 5, a plurality of fasteners 6 are arranged on the crossbeam of the rack 1 and arranged on the two sides of the heating furnace 5, the incident rod 2 and the transmission rod 3 are respectively fixed on each group of fasteners 6 and can move axially relative to the fasteners, the two locking blocks 7 are respectively fixed on the incident rod 2 and the transmission rod 3, the two driving members 8 are slidingly connected to the crossbeam and can rotate horizontally by 180°, the driving blocks 81 protruding from the driving members 8, the two driving members 8 are driven to move linearly by the electric driving mechanism arranged on the crossbeam, the driving blocks 81 of the driving members 8 abut against the corresponding locking blocks 7 to drive the incident rod 2 and the transmission rod 3 to move linearly towards the heating furnace 5 during the linear movement of the driving members 8, and the driving members 8 rotate horizontally by 180° to drive the incident rod 2 and the transmission rod 3 to move linearly away from the heating furnace 5.

[0034] The experimental process of the device is described as follows.

[0035] Before the formal experiment, the sample 9 is arranged in the heating furnace 5, the incident rod 2 and the transmission rod 3 are fixed, and the sample 9 is heated in the heating furnace 5, since the incident rod 2 and the transmission rod 3 are made of spring steel, the incident rod 2 and the transmission rod 3 need to be withdrawn from the furnace during the heating process, after the sample 9 is heated to the required temperature, the heating furnace 5 is closed, the air gun 4 starts to inflate, and the two driving members 8 are started, the two driving members 8 move linearly and drive the incident rod 2 and the transmission rod 3 to move linearly towards the heating furnace 5 by abutting against the corresponding locking blocks 7 through the corresponding driving blocks 81, and finally push the incident rod and the transmission rod into the furnace.

[0036] When the incident rod and the transmission rod are pushed into the furnace and contact the sample, the two driving members 8 rotate horizontally by 180° rapidly, so that the driving blocks 81 are horizontally adjusted by one position relative to the locking blocks 7 on the side. Figure 1 For example, the left transmission rod 3 on the middle left side, when the transmission rod 3 is pushed to move towards the heating furnace 5, the driving block 81 is located on the left side of the locking block 7 on the transmission rod 3 (as shown in Figure 3 ). Before the air gun 4 shoots the bullet, the driving block 81 rotates horizontally by 180° to the right side of the locking block 7 (as shown in Figure 4 ). The bullet (i.e. the shooting rod) of the air gun 4 hits the incident rod 2, and the sample 9 is pushed out of the furnace by the incident rod 2. The incident rod 2 and the transmission rod 3 are separated and move away from the electric driving mechanism after being impacted, which effectively avoids the damage of the electric driving mechanism.

[0037] The specific structure of the present application is further described in combination with the above experimental process as follows.

[0038] The electric driving mechanism in the application drives the electric linear guide rail 11 (the structure is a mature component, so the principle and structure of the electric linear guide rail 11 are not described in detail), and the linear free end of the electric linear guide rail 11 is fixedly connected with the driving piece 8 and drives the driving piece 8 to linearly displace on the rack 1.

[0039] As shown in Figure 5 , the structure for realizing the horizontal 180° rotation of the driving block 81 is as follows: A horizontal rotation structure for driving the driving piece 8 to horizontally rotate 180° is fixed on the electric linear guide rail 11, the horizontal rotation structure comprises a servo motor 12 and a rotating disc 13, the motor shaft of the servo motor 12 is fixed with the rotating disc 13, and the driving piece 8 is fixed on the rotating disc 13.

[0040] In order to further limit the rotation angle of the driving block 81, the horizontal rotation structure further comprises a limiting seat 14 and a limiting pin 15, the limiting seat 14 is fixed on the electric linear guide rail 11, the limiting pin 15 is fixed on the rotating disc 13 and rotates with the rotating disc 13, two circular arc open limiting grooves are symmetrically arranged on the limiting seat 14, the two limiting grooves are located on the rotation path of the limiting pin 15, and through the cooperation (corresponding proximity switch is arranged) of the limiting pin 15 and the limiting groove, the accurate switching of the driving block 81 between 0°-180° can be further ensured.

[0041] When the bullet of the gas gun 4 impacts the incident rod 2, in order to avoid directly separating from the transmission rod 3 rack, the spring buffer 10 is arranged on the rack 1, and the spring buffer 10 is located on one side of the transmission rod 3. The spring buffer 10 comprises a guide rod and a spring, the guide rod is a T-shaped rod, a position-adjustable mounting seat 16 is arranged on the cross beam of the rack 1, the guide rod is inserted into the mounting seat 16, a nut is axially limited by screwing on the guide rod, the spring is sleeved on the guide rod, and one end of the spring abuts against the mounting seat 16 and the other end abuts against the T-shaped head of the guide rod.

[0042] After the incident rod 2 impacts the transmission rod 3 and the transmission rod 3 impacts the spring buffer 10, the incident rod 2 and the transmission rod 3 will be bounced back, the locking block 7 will impact the driving block 81 in the rebound process, and the electric linear guide rail 11 can also be impacted to a certain extent, in order to reduce the impact damage caused by the rebound, the driving block 81 of the application can be unidirectionally vertically flipped on the driving piece 8. The specific structure is as follows: The driving block 81 is selected as a right-angle block, the horizontal edge of the driving block 81 is rotationally connected to the driving piece 8 through a rotating shaft, a torsional spring 82 is arranged on the rotating shaft, and the horizontal edge of the driving block 81 abuts against the driving piece 8 under the torsional spring force of the torsional spring 82.

[0043] The one-way vertical flip has the advantage that when the incident rod 2 and the transmission rod 3 rebound, the driving part 8 rotates horizontally by 180°, and the driving block 81 rotates to the initial state position for abutting against the locking block 7. When the locking block 7 abuts against the driving block 81 during rebounding, the driving block 81 is flipped, and at this time, the force of the locking block 7 hitting the driving block 81 can be effectively removed, and the impact on the electric linear guide rail 11 is reduced.

[0044] The outer edge of the vertical edge of the driving block 81 is an arc surface structure, which reduces damage to the locking block 7. After the arc surface of the driving block 81 contacts the locking block 7 after being flipped, it also has a certain "brake effect", which is used to stop the incident rod 2 and the transmission rod 3.

[0045] Since the SHPB test is based on one-dimensional stress wave theory and stress uniformity assumption, after the incident rod 2 and the transmission rod 3 are installed, the centering adjustment is performed, that is, it is necessary to ensure that the air gun 4, the incident rod 2, the transmission rod 3 and the sample 9 are on the same axis. The fastener 6 of the present application can adjust the height of the incident rod 2 and the transmission rod 3 in the vertical direction. The structure of the air gun 4 and the vertical adjustment structure are conventional structures, and the present application does not describe the structure of the air gun 4 itself and the vertical direction lifting.

[0046] The vertical height of the spring buffer 10 can be unchanged, and only the T-head area of the guide rod needs to be enlarged. The structure of the fastener 6 is described in detail below.

[0047] As Figure 6 , the fastener 6 includes an upper seat 61, a lower seat 62, an adjusting rod 63 and a roller 64. The upper seat 61 and the lower seat 62 are fixed and integrated in a quick release structure, three adjusting rods 63 are arranged at equal angles and connected to the upper seat 61 and the lower seat 62. In this embodiment, two adjusting rods 63 are arranged on the lower seat 62, and one adjusting rod 63 is arranged on the upper seat 61. The roller 64 is rotatably connected to the end of the adjusting rod 63. The adjusting rod 63 is a hand screw structure, and the corresponding positions of the upper seat 61 and the lower seat 62 are adjustable, which is used to adjust the relative distance between the three rollers 64.

[0048] The three rollers 64 abut and clamp the corresponding incident rod 2 and transmission rod 3, and the roller 64 can ensure the axial movement of the incident rod 2 and the transmission rod 3 relative to the fastener 6.

[0049] As Figure 7The quick release structure between the upper seat 61 and the lower seat 62 is that two inserting ribs 611 are symmetrically arranged on the upper seat 61, the inserting rib 611 is provided with a buckling groove, the lower seat 62 is provided with an inserting groove, a lock buckle 621 and a spring 622, the lock buckle 621 is rotationally connected to the lower seat 62 and extends into the inserting groove at one end, the spring 622 is arranged in the inserting groove and abuts against the lock buckle 621 at one end and the inner wall of the inserting groove at the other end, the inserting rib 611 is inserted into the inserting groove, and the corresponding end of the lock buckle 621 abuts against the buckling groove under the spring force. When the upper seat 61 and the lower seat 62 need to be removed, the lock buckle 621 is pulled (at this time, the spring 622 is compressed), the lock buckle 621 is separated from the buckling groove on the inserting rib 611, and then the upper seat 61 can be pulled out.

[0050] As Figure 8 The heating furnace 5 in the application comprises an outer insulation cover 51, an electric heating pipe 52 and an inner insulation pipe 53, the electric heating pipe 52 and the inner insulation pipe 53 are coaxially arranged, the inner insulation pipe 53 is arranged in the electric heating pipe 52, the electric heating pipe 52 is arranged in the outer insulation cover 51, and the sample 9 is arranged in the inner insulation pipe 53.

[0051] As Figure 9 After the sample 9 is arranged in the inner insulation pipe 53, the limit groove is arranged on the inner wall of the inner insulation pipe 53 in the axial direction to avoid the sample 9 from falling, and the limit rib 91 is arranged on the outer wall of the sample 9 and is slidingly arranged in the limit groove.

[0052] The above only describes the preferred embodiments of the application, and it should be noted that the ordinary skilled in the art can make several improvements without departing from the principles of the application, and these improvements should also be considered as the protection scope of the application.

Claims

1. A high-temperature SHPB dynamic compression test device, comprising a frame (1), an incident rod (2), a transmission rod (3), an air gun (4) and a heating furnace (5), wherein the air gun (4) and the heating furnace (5) are fixed to the frame (1), the incident rod (2) and the transmission rod (3) are arranged on both sides of the heating furnace (5), and strain gauges are attached to the incident rod and the transmission rod, characterized in that: The invention also includes a fastener (6), a locking block (7), a driving member (8) and a sample (9), wherein the sample (9) is placed in a heating furnace (5), a plurality of fasteners (6) are divided into two groups and are fixed on a frame (1) and placed on both sides of the heating furnace (5), an incident rod (2) and a transmission rod (3) are respectively fixed on each group of fasteners (6), and can move axially relative to the fasteners, two locking blocks (7) are respectively fixed on the incident rod (2) and the transmission rod (3), two driving members (8) are slidably connected to the frame (1), and the driving member (8) is connected to the frame (1). The moving member (8) can rotate horizontally. A protruding driving block (81) is provided on the driving member (8). The two driving members (8) are driven by an electric driving mechanism arranged on the frame (1) to move linearly. During the linear displacement of the driving member (8), the driving block (81) contacts the corresponding locking block (7) to drive the incident rod (2) and the transmission rod (3) to move linearly toward the heating furnace (5). The driving member (8) rotates horizontally by 180 degrees to allow the incident rod (2) and the transmission rod (3) to move linearly away from the heating furnace (5).

2. The high-temperature SHPB dynamic compression test device according to claim 1, characterized in that: The electric drive mechanism is an electric linear guide rail (11), which drives the driving member (8) to linearly move on the frame (1). A horizontal rotation structure for driving the driving member (8) to rotate horizontally 180 degrees is fixed on the electric linear guide rail (11). The horizontal rotation structure includes a servo motor (12) and a turntable (13). The motor shaft of the servo motor (12) is fixed to the turntable (13), and the driving member (8) is fixed on the turntable (13).

3. The high-temperature SHPB dynamic compression test device according to claim 2, characterized in that: The horizontal rotation structure further comprises a limit seat (14) and a limit pin (15), wherein the limit seat (14) is fixed on the electric linear guide rail (11), the limit pin (15) is fixed on the turntable (13) and rotates with the turntable (13), and two limit slots are provided on the limit seat (14) and on the rotation path of the limit pin (15).

4. The high-temperature SHPB dynamic compression test device according to claim 1, characterized in that: A spring buffer (10) is provided on the frame (1), and the spring buffer (10) is located on one side of the transmission rod (3).

5. The high-temperature SHPB dynamic compression test device according to claim 1, characterized in that: The driving block (81) can be flipped vertically in one direction on the driving member (8).

6. The high-temperature SHPB dynamic compression test device according to claim 5, characterized in that: The driving block (81) is a right-angle block, which is rotatably connected to the driving member (8) via a rotating shaft. A torsion spring (82) is provided on the rotating shaft. Under the torsion spring force of the torsion spring (82), the horizontal edge of the driving block (81) contacts the driving member (8).

7. The high-temperature SHPB dynamic compression test device according to claim 1, characterized in that: The fastener (6) includes an upper seat (61), a lower seat (62), an adjusting rod (63) and a roller (64). The upper seat (61) and the lower seat (62) are fixed together using a quick-release structure. Three adjusting rods (63) are arranged at equal angles and connected to the upper seat (61) and the lower seat (62). The roller (64) is rotatably connected to the end of the adjusting rod (63). The adjusting rod (63) is adjustable on the corresponding upper seat (61) and the lower seat (62) to adjust the relative distance between the three rollers (64).

8. The high-temperature SHPB dynamic compression test device according to claim 7, characterized in that: The quick-detachable structure is as follows: two inserting bars (611) are symmetrically provided on the upper seat (61), a buckle groove is provided on the inserting bar (611), a slot, a lock buckle (621) and a spring (622) are provided on the lower seat (62), the lock buckle (621) is rotatably connected to the lower seat (62) and one end extends into the slot, the spring (622) is provided in the slot, one end abuts against the lock buckle (621) and the other end abuts against the inner wall of the slot, the inserting bar (611) is plugged into the slot, and the corresponding end of the lock buckle (621) abuts against the buckle groove under the action of the spring elastic force.

9. The high-temperature SHPB dynamic compression test device according to claim 1, characterized in that: The heating furnace (5) includes an outer insulation cover (51), an electric heating tube (52) and an inner insulation tube (53), wherein the electric heating tube (52) and the inner insulation tube (53) are coaxially arranged, and the inner insulation tube (53) is placed inside the electric heating tube (52), the electric heating tube (52) is placed inside the outer insulation cover (51), and the sample (9) is placed inside the inner insulation tube (53).

10. The high-temperature SHPB dynamic compression test device according to claim 9, characterized in that: A limiting groove is provided in the axial direction of the inner wall of the inner thermal insulation pipe (53), and a limiting rib (91) is provided on the outer wall of the sample (9), and the limiting rib is slidably placed in the limiting groove.

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