Equipment for testing axial mechanical property of small-size pipe body

Abstract

The invention relates to the technical field of thin-walled tube performance testing, in particular to equipment for testing the axial mechanical property of a small-size tube body, and solves the problems that a thin-walled tube cannot be processed into a thin plate due to size limitation as a thin plate sample is used in an existing standard small-punch testing method, and the thin-walled tube cannot be processed into the thin plate due to the double-stress effect on the standard small-punch testing sample. And the method can not be used for testing the mechanical properties of anisotropic materials. The device comprises a sample-changing force-applying mechanism and testing mechanisms, the outer side of the sample-changing force-applying mechanism is provided with a separating and combining mechanism, the inner side of the sample-changing force-applying mechanism is provided with a plurality of testing mechanisms, each testing mechanism comprises a sample clamp, and the inner side of the upper end of each sample clamp is provided with a force measuring mechanism. A displacement measuring mechanism is mounted on the inner side of the bottom end of the sample clamp. According to the thin-walled tube axial mechanical property testing device, the thin-walled tube is subjected to tiny sample cutting, the axial mechanical property of the thin-walled tube can be effectively tested, multiple tiny samples are synchronously tested and replaced, and the testing result is more accurate.

Description

Technical Field

[0001] The invention relates to the technical field of thin-walled tube performance testing, in particular to a device for testing the axial mechanical properties of a small-sized tube body. Background Art

[0002] Thin-walled tubes need to be tested for mechanical properties after forming. Thin-walled tubes are generally made by drawing forming. Under this manufacturing process, some thin-walled tubes will show anisotropic mechanical properties. Under the condition of limited tube length, in order to test the mechanical properties of the tube, a micro-sample test method is required. Small punch technology is a micro-sample test method, and its standard sample is a disc with a diameter of 10mm and a thickness of 0.5mm. Since its birth in 1981, this technology has been widely used to test the tensile, creep, fracture toughness and other mechanical properties of materials.

[0003] The existing standard small punch test method uses a thin plate specimen. Due to size limitations, thin-walled tubes cannot be processed into thin plates. In addition, the standard small punch specimen is subject to double stress and cannot be used to test the mechanical properties of anisotropic materials. Therefore, it does not meet existing needs. In this regard, we propose a device for testing the axial mechanical properties of small-sized tubes. Summary of the invention

[0004] The purpose of the present invention is to provide a device for testing the axial mechanical properties of small-sized pipes, so as to solve the problem that the existing standard small punch test method proposed in the above background technology uses a thin plate specimen, and the thin-walled pipe cannot be processed into a thin plate due to size limitations, and the standard small punch test specimen is subjected to double stress and cannot be used to test the mechanical properties of anisotropic materials.

[0005] To achieve the above-mentioned object, the present invention provides the following technical solutions: a device for testing the axial mechanical properties of a small-sized tube, comprising a sample changing force adding mechanism and a testing mechanism, wherein a separation and combination mechanism is installed on the outer side of the sample changing force adding mechanism, and a plurality of testing mechanisms are installed on the inner side of the sample changing force adding mechanism, wherein the testing mechanism comprises a sample fixture, wherein a force measuring mechanism is installed on the inner side of the upper end of the sample fixture, and a displacement measuring mechanism is installed on the inner side of the bottom end of the sample fixture, wherein a tubular sample is installed between the force measuring mechanism and the displacement measuring mechanism, and wherein two waist-shaped holes are provided in the middle of the tubular sample; The sample fixture comprises a positioning base plate, a lower fixture is fixedly mounted on the upper end surface of the positioning base plate, an upper fixture is mounted on the upper end surface of the lower fixture, a plurality of positioning columns are mounted between the lower fixture and the upper fixture, a lofting arc groove is provided in the middle of the upper end of the lower fixture, and a positioning arc strip is mounted on the inner wall of the lofting arc groove.

[0006] Preferably, the force measuring mechanism includes an arc head punch rod, the bottom end of the arc head punch rod is provided with an arc contact surface, the upper end of the arc head punch rod is installed with a transmission pressure block, a force sensor is installed between the arc head punch rod and the transmission pressure block, and the arc head punch rod, the transmission pressure block and the force sensor are connected by threads.

[0007] The displacement measuring mechanism comprises a mounting sleeve, a displacement sensor is mounted on the inner side of the mounting sleeve, a follower rod is slidably connected between the displacement sensors, a limit plate is mounted on the outer side of the upper end of the follower rod, and a support spring is arranged between the limit plate and the mounting sleeve.

[0008] Preferably, the separation and combination mechanism includes a supporting base, an installation box is fixedly installed on the upper end surface of the supporting base, a transmission screw is rotatably connected to the inner side of one end angle of the installation box, guide columns are fixedly installed on the inner sides of the other three end angles of the installation box, a connecting frame is installed on the upper ends of the transmission screw and the three guide columns, and a transmission motor is fixedly installed on one of the end angles of the upper end surface of the connecting frame.

[0009] Preferably, the sample-changing force-applying mechanism comprises a mounting frame, a control panel is fixedly mounted in the middle of the front end of the mounting frame, cylinders are fixedly mounted at both ends of the mounting frame, a first connecting rod is mounted at the output end of the cylinder, a second connecting rod is mounted at one end of the first connecting rod, a flip positioning plate is rotatably connected to the inner side of the mounting frame, a plurality of DC servo motors are fixedly mounted on the upper end surface of the flip positioning plate, and a motor support seat is fixedly mounted on the upper end of the DC servo motor.

[0010] Preferably, the output end of the transmission motor passes through one of the end angles of the connecting frame and is connected to the upper end of the transmission screw through a coupling, the transmission screw is connected to the mounting frame through a threaded connection, the mounting frame is slidingly connected to the three guide columns, and the other three end angles of the connecting frame are fixedly connected to the three guide columns.

[0011] Preferably, the output end of the cylinder is rotatably connected to the first connecting rod via a pin, the first connecting rod and the second connecting rod are rotatably connected via a pin, and one end of the two second connecting rods away from the first connecting rod are fixedly connected to both ends of the flip positioning plate.

[0012] Preferably, the plurality of motor support seats and testing mechanisms are arranged in an array on the upper end surface of the flip positioning plate, the output end of the DC servo motor passes through the motor support seat and is fixedly connected to the upper end of the transmission pressure block, the transmission pressure block is fixedly connected to the force sensor, and the arc head punch is slidably connected to the upper clamp.

[0013] Preferably, the upper end of the force sensor is fixedly connected to the transmission pressure block by means of threads, the lower end surface of the force sensor is in close contact with the arc head punch rod, and the force sensor, displacement sensor and control panel are electrically connected.

[0014] Preferably, the mounting sleeve is connected to the lower clamp by a threaded connection, the mounting sleeve is connected to the displacement sensor by a threaded connection, the upper end of the follower rod passes through the displacement sensor, the mounting sleeve, the support spring and the limit plate and is inserted into the inner side of the middle part of the lower clamp, the follower rod is slidably connected to the mounting sleeve and the displacement sensor, the follower rod is fixedly connected to the limit plate, and the upper end of the mounting sleeve is connected to the limit plate by a support spring.

[0015] Preferably, the upper end surface of the impact zone of the tubular sample is in contact with the arc-shaped contact surface, the middle part of the lower end surface of the impact zone of the tubular sample is in contact with the follower rod, the arc-shaped contact surface is arranged between two waist-shaped holes, the two waist-shaped holes are symmetrically installed relative to the axis of the arc-shaped punch, and the thickness dimension h of the tubular sample is 0.5 mm; The upper end of the lower clamp is connected to multiple positioning columns by threads, the bottom end of the upper clamp is slidably connected to multiple positioning columns, the flip positioning plate is connected to the upper ends of multiple upper clamps by threads, the tubular specimen is arranged between the upper clamp and the lower clamp, the positioning arc strip is fixedly connected to the lower clamp, and one end of the tubular specimen is in fit contact with one side of the positioning arc strip.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention pushes the first connecting rod with two cylinders and drives the flip positioning plate to flip relative to the mounting frame through the second connecting rod. At this time, it is convenient to place multiple tubular specimens synchronously on the inner side of the sample arc groove, and then the end of the tubular specimen can be positioned by the positioning arc strip, so as to ensure the accuracy of the placement of the tubular specimen. The transmission motor drives the sample changing force adding mechanism to move downward through the transmission screw, and the lower fixture can be positioned and molded with the upper fixture through multiple positioning columns. The two waist-shaped holes are symmetrically installed relative to the axis of the arc head punch. The DC servo motor performs synchronous force adding operation on the tubular specimen through the force measuring mechanism, which is convenient for synchronously performing different load test operations on multiple tubular specimens. 2. The present invention can measure the force applied by the arc-head punch to the tubular specimen through the force sensor, thereby facilitating the measurement of the loads on multiple tubular specimens. The tubular specimen is deformed by the force and presses the follower rod downward. Then, when the follower rod moves downward, the support spring is compressed by the limit plate, and then the displacement of the follower rod can be measured by the displacement sensor, thereby realizing the displacement measurement of the deformation of the tubular specimen and realizing the simultaneous axial tensile performance test operation of multiple thin-walled tubes. After the test is completed, the multiple tubular specimens can be replaced by separating the lower clamp and the upper clamp, and the follower rod can automatically reset under the support of the support spring through the limit plate, thereby facilitating repeated testing of the tubular specimens. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 A top view of the sample changing and forcing mechanism of the present invention; Figure 3 It is a structural schematic diagram of the sample changing force adding mechanism of the present invention; Figure 4 It is a schematic cross-sectional structure diagram of the present invention as a whole; Figure 5 It is a structural schematic diagram of the testing mechanism of the present invention; Figure 6 It is a schematic diagram of the cross-sectional structure of the testing mechanism of the present invention; Figure 7 It is a schematic diagram of the explosion structure of the testing mechanism of the present invention; Figure 8 It is a schematic diagram of the structure of the tubular sample of the present invention; Fig. 9 is a load curve diagram of the tubular specimen of the present invention; Fig.10 It is a schematic diagram of the maximum load of the tubular specimen of the present invention; Fig.11 It is a schematic diagram of the structure of the tubular sample of the present invention.

[0018] In the figure: 1. Splitting and closing mechanism; 101. Support base; 102. Mounting box; 103. Guide column; 104. Connecting frame; 105. Transmission screw; 106. Transmission motor; 2. Sample changing and forcing mechanism; 201. Mounting frame; 202. Control panel; 203. Flip positioning plate; 204. Cylinder; 205. Motor support seat; 206. DC servo motor; 207. First connecting rod; 208. Second connecting rod; 3. Testing mechanism; 4. Sample fixture; 401. Fixing 402, bottom plate; 403, upper fixture; 404, positioning column; 405, arc groove; 406, positioning arc strip; 5, force measurement mechanism; 501, transmission pressure block; 502, arc contact surface; 503, force sensor; 504, arc head punch; 6, displacement measurement mechanism; 601, mounting sleeve; 602, follower rod; 603, displacement sensor; 604, support spring; 605, limit plate; 7, tubular specimen; 701, impact zone; 8, waist-shaped hole. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0020] See also Figures 1 to 4 An embodiment of the present invention provides a device for testing the axial mechanical properties of a small-sized tube, comprising a sample changing and forcing mechanism 2 and a testing mechanism 3, a separation and combination mechanism 1 is installed on the outer side of the sample changing and forcing mechanism 2, and the separation and combination mechanism 1 comprises a support base 101, and a mounting box 102 is fixedly installed on the upper end surface of the support base 101, and a transmission screw 105 is rotatably connected to the inner side of one end corner of the mounting box 102, and guide columns 103 are fixedly installed on the inner sides of the other three end corners of the mounting box 102, and a transmission screw 105 and the upper ends of the three guide columns 103 are installed. A connecting frame 104 is provided, and the other three end corners of the connecting frame 104 are fixedly connected to the three guide columns 103. A transmission motor 106 is fixedly installed on one of the end corners of the upper end surface of the connecting frame 104. The output end of the transmission motor 106 passes through one of the end corners of the connecting frame 104 and is connected to the upper end of the transmission screw 105 through a coupling, so that the transmission motor 106 drives the sample changing force mechanism 2 to move downward on the outer sides of the three guide columns 103 through the transmission screw 105 under the support of the connecting frame 104, thereby realizing the mold closing operation of the sample fixture 4.

[0021] See also Figure 5 and Figure 6A plurality of testing mechanisms 3 are installed on the inner side of the sample changing force applying mechanism 2, and the testing mechanism 3 includes a sample fixture 4, a force measuring mechanism 5 is installed on the inner side of the upper end of the sample fixture 4, a displacement measuring mechanism 6 is installed on the inner side of the bottom end of the sample fixture 4, a tubular sample 7 is installed between the force measuring mechanism 5 and the displacement measuring mechanism 6, two waist-shaped holes 8 are provided in the middle of the tubular sample 7, the upper end surface of the tubular sample 7 is in contact with the arc-shaped contact surface 502, the middle part of the lower end surface of the tubular sample 7 is in contact with the follower rod 602, the arc-shaped contact surface 502 is arranged between the two waist-shaped holes 8, the two waist-shaped holes 8 are symmetrically installed relative to the axis of the arc head punch 504, the thickness dimension h of the tubular sample 7 is 0.5 mm, and the mechanical properties of the tubular sample 7 can be tested by applying a load to the impact zone 701 between the two waist-shaped holes 8.

[0022] See also Figure 5 , Figure 6 , Figure 7 , Figure 8 and Fig.11 The sample fixture 4 includes a positioning base plate 401, a lower fixture 402 is fixedly installed on the upper end surface of the positioning base plate 401, an upper fixture 403 is installed on the upper end surface of the lower fixture 402, the flip positioning plate 203 and the upper ends of the plurality of upper fixtures 403 are connected by threads, the tubular sample 7 is arranged between the upper fixture 403 and the lower fixture 402, a plurality of positioning posts 404 are installed between the lower fixture 402 and the upper fixture 403, and the upper end of the lower fixture 402 and the plurality of positioning posts 404 are connected by threads. Threaded connection, the bottom end of the upper clamp 403 is slidably connected to multiple positioning columns 404, a layout arc groove 405 is provided in the middle of the upper end of the lower clamp 402, and a positioning arc strip 406 is installed on the inner wall of the layout arc groove 405. The positioning arc strip 406 is fixedly connected to the lower clamp 402, and one end of the tubular sample 7 is in contact with one side of the positioning arc strip 406. The end of the tubular sample 7 can be positioned by the positioning arc strip 406, thereby ensuring the accuracy of the placement of the tubular sample 7.

[0023] See also Figure 6 and Figure 7The force measuring mechanism 5 includes an arc-head punch rod 504, so that the motor support seat 205 performs synchronous testing operation on the tubular sample 7 through the force measuring mechanism 5 under the support of the DC servo motor 206. The arc-head punch rod 504 is slidably connected to the upper clamp 403, and the bottom end of the arc-head punch rod 504 is provided with an arc-shaped contact surface 502. The upper end of the arc-head punch rod 504 is installed with a transmission pressure block 501. A force sensor 503 is installed between the arc-head punch rod 504 and the transmission pressure block 501. The upper end of the force sensor 503 is connected to the transmission pressure block 501 through a thread, and the lower end surface of the force sensor 503 is in contact with the arc-head punch rod 504. The force applied by the arc-head punch rod 504 to the tubular sample 7 can be measured through the force sensor 503, which is convenient for synchronously performing testing operations on multiple tubular samples 7 with different loads.

[0024] See also Figure 6 and Figure 7 The displacement measuring mechanism 6 includes a mounting sleeve 601, which is connected to the lower fixture 402 by threads, a displacement sensor 603 is installed on the inner side of the mounting sleeve 601, the mounting sleeve 601 and the displacement sensor 603 are connected by threads, a follower rod 602 is slidably connected between the displacement sensor 603, the follower rod 602 is slidably connected to the mounting sleeve 601 and the displacement sensor 603, a limiting plate 605 is installed on the outer side of the upper end of the follower rod 602, the follower rod 602 is fixedly connected to the limiting plate 605, and a support spring 604 is provided between the limiting plate 605 and the mounting sleeve 601, The upper end of the follower rod 602 passes through the displacement sensor 603, the mounting sleeve 601, the support spring 604 and the limit plate 605 and is inserted into the inner side of the middle part of the lower clamp 402. The upper end of the mounting sleeve 601 is connected to the limit plate 605 through the support spring 604. The deformation of the tubular sample 7 will press down the follower rod 602, and then when the follower rod 602 moves downward, the support spring 604 is compressed through the limit plate 605, and then the displacement of the follower rod 602 can be detected through the displacement sensor 603, thereby realizing the displacement measurement of the tubular sample 7 in the vertical direction after the deformation under force.

[0025] See also Figure 3 and Figure 4The sample changing force adding mechanism 2 includes a mounting frame 201, a driving screw 105 is connected to the mounting frame 201 by threads, the mounting frame 201 is slidably connected to the three guide columns 103, a control panel 202 is fixedly installed in the middle of the front end of the mounting frame 201, a force sensor 503, a displacement sensor 603 and the control panel 202 are electrically connected, a cylinder 204 is fixedly installed at both ends of the mounting frame 201, a first connecting rod 207 is installed at the output end of the cylinder 204, and the output end of the cylinder 204 is rotatably connected to the first connecting rod 207 by a pin. Then, a second connecting rod 208 is installed at one end of the first connecting rod 207, and the first connecting rod 207 and the second connecting rod 208 are rotatably connected by a pin, and one end of the two second connecting rods 208 away from the first connecting rod 207 is fixedly connected to both ends of the flip positioning plate 203, and the inner side of the mounting frame 201 is rotatably connected with the flip positioning plate 203, so that the two cylinders 204 push the first connecting rod 207 and drive the flip positioning plate 203 to flip relative to the mounting frame 201 through the second connecting rod 208, which is convenient for synchronous sampling and placement of multiple tubular specimens 7; A plurality of DC servo motors 206 are fixedly mounted on the upper end surface of the flip positioning plate 203, a motor support seat 205 is fixedly mounted on the upper end of the DC servo motor 206, and the plurality of motor support seats 205 and the testing mechanism 3 are arranged in an array on the upper end surface of the flip positioning plate 203. The output end of the DC servo motor 206 passes through the motor support seat 205 and is fixedly connected to the upper end of the transmission pressure block 501, so that the DC servo motor 206 performs synchronous testing operations on the tubular sample 7 through the force measuring mechanism 5 under the support of the motor support seat 205.

[0026] See also Fig. 9 The force-displacement curve obtained from the test of tubular specimen 7 can be divided into four stages, namely elastic deformation stage (I), plastic deformation stage (II), film stretching stage (III) and plastic instability and fracture stage (IV). The yield strength of tubular specimen 7 ( ) and tensile strength ( )for: ; ; in is the initial thickness of the tubular sample 7, is the maximum load during the test of tubular specimen 7, is the displacement of the follower rod 602, and is the correlation coefficient for the test on tubular specimen 7, is the elastic-plastic transition force.

[0027] See also Fig.10 , The value of can be obtained by the method specified in the European standard EN10372 or the American standard ASTME3205. According to the method specified in the European standard EN10372, the elastic-plastic transition force It is fitted by the following bilinear equations: ; in is the elastic-plastic transition force, For The displacement at is the initial thickness of the tubular sample 7 , For The load at the position, the parameters of the bilinear equations , and It is determined by the minimum fitting error, which can be calculated as follows: ; When the fitting error reaches the minimum, It is the elastic-plastic transition stress measured by the method specified in the European standard EN10372. , recorded as ; Find the minimum fitting error Later, the American standard ASTME3205 proposed to draw a vertical straight line through the intersection point A of the two linear curves, which intersects with the load-displacement curve obtained by the small punch test at point C. At this time, the load value corresponding to point C is , which is derived from the American standard ASTME3205 , recorded as .

[0028] When in use, when a small punch test is performed on a thin-walled tube, the thin-walled tube is processed into a tubular sample 7 using a wire cutting method. If the thickness h of the tubular sample 7 is much larger than 0.5 mm, it needs to be thinned. When the power is turned on, the lower clamp 402 and the upper clamp 403 are separated in the initial state, and the two cylinders 204 are started, so that the two cylinders 204 push the first connecting rod 207 and drive the flip positioning plate 203 to flip relative to the mounting frame 201 through the second connecting rod 208. At this time, it is convenient to place multiple tubular samples 7 synchronously on the inner side of the lofting arc groove 405, and then the end of the tubular sample 7 can be positioned by positioning the arc strip 406, thereby ensuring the accuracy of the placement of the tubular sample 7; The flip positioning plate 203 is reset relative to the mounting frame 201, and the transmission motor 106 is started, so that the transmission motor 106 drives the sample changing force applying mechanism 2 to move downward on the outside of the three guide columns 103 through the transmission screw 105 under the support of the connecting frame 104, and then the flip positioning plate 203 drives the multiple force measuring mechanisms 5 to move downward synchronously through the upper clamp 403, and the lower clamp 402 can perform positioning and mold closing operations with the upper clamp 403 through multiple positioning columns 404. At this time, the bottom end of the arc head punch 504 passes through the upper clamp 403 and fits and contacts with the upper end surface of the tubular sample 7, and the follower rod 602 can fit and contact with the middle part of the lower end surface of the tubular sample 7 through the limit plate 605 under the support of the support spring 604, and the two waist-shaped holes 8 are symmetrically installed relative to the axis of the arc head punch 504; Synchronously start multiple DC servo motors 206, so that the DC servo motors 206 can perform synchronous testing operations on the tubular sample 7 through the force measuring mechanism 5 under the support of the motor support seat 205, wherein a force sensor 503 is provided between the transmission pressure block 501 and the arc punch 504, so that the control panel 202 can measure and display the force applied by the arc punch 504 to the tubular sample 7 through the force sensor 503, thereby facilitating the testing of the loads on the multiple tubular samples 7, and an arc contact surface 502 is provided at the bottom end of the arc punch 504, and the arc contact surface 502 is completely in contact with the surface of the impact zone 701, so that the arc punch 504 can effectively maintain the uniform pressurization of the impact zone 701 of the tubular sample 7; During the test of the tubular sample 7, the tubular sample 7 is deformed and presses down the follower rod 602, and then when the follower rod 602 moves downward, the support spring 604 is compressed through the limit plate 605, and then the displacement of the follower rod 602 can be detected by the displacement sensor 603, thereby realizing the measurement of the displacement of the tubular sample 7 in the vertical direction, which is convenient for synchronously performing axial tensile performance testing operations on multiple thin-walled tubes. After the test is completed, multiple tubular samples 7 can be replaced by separating the lower clamp 402 and the upper clamp 403, and the follower rod 602 can automatically reset through the limit plate 605 under the support of the support spring 604, thereby facilitating repeated testing of the tubular sample 7.

[0029] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A device for testing the axial mechanical properties of a small-sized tube, comprising a sample changing and force applying mechanism (2) and a testing mechanism (3), characterized in that: The outer side of the sample changing force applying mechanism (2) is provided with a separation and combination mechanism (1), the inner side of the sample changing force applying mechanism (2) is provided with a plurality of testing mechanisms (3), the testing mechanism (3) comprising a sample clamp (4), the inner side of the upper end of the sample clamp (4) is provided with a force measuring mechanism (5), the inner side of the lower end of the sample clamp (4) is provided with a displacement measuring mechanism (6), a tubular sample (7) is provided between the force measuring mechanism (5) and the displacement measuring mechanism (6), and two waist-shaped holes (8) are provided in the middle of the tubular sample (7); The sample fixture (4) comprises a positioning base plate (401), a lower fixture (402) is fixedly mounted on the upper end surface of the positioning base plate (401), an upper fixture (403) is mounted on the upper end surface of the lower fixture (402), a plurality of positioning columns (404) are mounted between the lower fixture (402) and the upper fixture (403), a lofting arc groove (405) is provided in the middle of the upper end of the lower fixture (402), and a positioning arc strip (406) is mounted on the inner wall of the lofting arc groove (405).

2. The device for testing the axial mechanical properties of a small-sized pipe according to claim 1, characterized in that: The force measuring mechanism (5) comprises an arc-shaped punch rod (504), the bottom end of the arc-shaped punch rod (504) is provided with an arc-shaped contact surface (502), the upper end of the arc-shaped punch rod (504) is provided with a transmission pressure block (501), a force sensor (503) is provided between the arc-shaped punch rod (504) and the transmission pressure block (501), and the arc-shaped punch rod (504), the transmission pressure block (501) and the force sensor (503) are connected via threads; The displacement measuring mechanism (6) comprises a mounting sleeve (601), a displacement sensor (603) being mounted on the inner side of the mounting sleeve (601), a follower rod (602) being slidably connected between the displacement sensor (603), a limit plate (605) being mounted on the outer side of the upper end of the follower rod (602), and a support spring (604) being provided between the limit plate (605) and the mounting sleeve (601).

3. The device for testing the axial mechanical properties of a small-sized pipe according to claim 2, characterized in that: The splitting and combining mechanism (1) comprises a supporting base (101), an installation box (102) being fixedly mounted on the upper end surface of the supporting base (101), a transmission screw (105) being rotatably connected to the inner side of one end angle of the installation box (102), guide columns (103) being fixedly mounted on the inner sides of the other three end angles of the installation box (102), a connecting frame (104) being mounted on the upper ends of the transmission screw (105) and the three guide columns (103), and a transmission motor (106) being fixedly mounted on one end angle of the upper end surface of the connecting frame (104).

4. The device for testing the axial mechanical properties of a small-sized pipe according to claim 3, characterized in that: The sample changing force adding mechanism (2) comprises a mounting frame (201), a control panel (202) being fixedly mounted in the middle of the front end of the mounting frame (201), cylinders (204) being fixedly mounted at both ends of the mounting frame (201), a first connecting rod (207) being mounted at the output end of the cylinder (204), a second connecting rod (208) being mounted at one end of the first connecting rod (207), a flip positioning plate (203) being rotatably connected to the inner side of the mounting frame (201), a plurality of DC servo motors (206) being fixedly mounted on the upper end surface of the flip positioning plate (203), and a motor support seat (205) being fixedly mounted on the upper end of the DC servo motor (206).

5. The device for testing the axial mechanical properties of a small-sized pipe according to claim 4, characterized in that: The output end of the transmission motor (106) passes through one of the end corners of the connection frame (104) and is connected to the upper end of the transmission screw (105) via a coupling; the transmission screw (105) is threadedly connected to the mounting frame (201); the mounting frame (201) is slidably connected to the three guide columns (103); and the other three end corners of the connection frame (104) are fixedly connected to the three guide columns (103).

6. The device for testing the axial mechanical properties of a small-sized pipe according to claim 5, characterized in that: The output end of the cylinder (204) is rotatably connected to the first connecting rod (207) via a pin, the first connecting rod (207) is rotatably connected to the second connecting rod (208) via a pin, and the ends of the two second connecting rods (208) away from the first connecting rod (207) are fixedly connected to both ends of the flip positioning plate (203).

7. The device for testing the axial mechanical properties of a small-sized pipe according to claim 6, characterized in that: The plurality of motor support seats (205) and the testing mechanism (3) are arranged in an array on the upper end surface of the flip positioning plate (203); the output end of the DC servo motor (206) passes through the motor support seat (205) and is fixedly connected to the upper end of the transmission pressure block (501); the transmission pressure block (501) is fixedly connected to the force sensor (503); and the arc head punch (504) is slidably connected to the upper clamp (403).

8. The device for testing the axial mechanical properties of a small-sized pipe according to claim 7, characterized in that: The upper end of the force sensor (503) is fixedly connected to the transmission pressure block (501) via a thread, the lower end surface of the force sensor (503) is in close contact with the arc-head punch rod (504), and the force sensor (503), the displacement sensor (603) and the control panel (202) are electrically connected.

9. The device for testing the axial mechanical properties of a small-sized pipe according to claim 8, characterized in that: The mounting sleeve (601) is connected to the lower fixture (402) via a threaded connection, the mounting sleeve (601) is connected to the displacement sensor (603) via a threaded connection, the upper end of the follower rod (602) passes through the displacement sensor (603), the mounting sleeve (601), the support spring (604) and the limit plate (605) and is plugged into the inner side of the middle of the lower fixture (402), the follower rod (602) is slidably connected to the mounting sleeve (601) and the displacement sensor (603), the follower rod (602) is fixedly connected to the limit plate (605), and the upper end of the mounting sleeve (601) is connected to the limit plate (605) via the support spring (604).

10. The device for testing the axial mechanical properties of a small-sized pipe according to claim 9, characterized in that: The upper end surface of the tubular sample (7) is completely in contact with the arc-shaped contact surface (502), the middle portion of the lower end surface of the tubular sample (7) is in contact with the follower rod (602), the arc-shaped contact surface (502) is arranged between two waist-shaped holes (8), the two waist-shaped holes (8) are symmetrically installed relative to the axis of the arc-head punch (504), and the thickness dimension h of the tubular sample (7) is 0.5 mm; The upper end of the lower clamp (402) is connected to the plurality of positioning posts (404) by threads, the bottom end of the upper clamp (403) is slidably connected to the plurality of positioning posts (404), the flip positioning plate (203) is connected to the upper ends of the plurality of upper clamps (403) by threads, the tubular specimen (7) is arranged between the upper clamp (403) and the lower clamp (402), the positioning arc strip (406) is fixedly connected to the lower clamp (402), and one end of the tubular specimen (7) is in close contact with one side of the positioning arc strip (406).

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