Axial compression centering device for pipe parts

Abstract

The invention discloses an axial compression centering device for pipe parts. The axial compression centering device comprises an upper compression platform, a lower compression platform, a guide mechanism and a positioning mechanism, the guide mechanism comprises a guide block, an outer ring, a guide column and a spring; the positioning mechanism comprises a positioning ring and a connecting rod; the upper compression platform is located over the lower compression platform. The center position of the top of the upper compression platform is connected with an upper chuck of a testing machine; the center position of the bottom of the lower compression platform is connected with a lower chuck of the testing machine; a plurality of guide blocks are placed at the top of the lower compression platform; the inner side surfaces of the plurality of guide blocks are encircled to form an accommodating cavity for placing a test piece; a guide column is arranged on the outer side surface of each guide block; each guide column is sleeved with a spring; the bottom of the outer ring is connected with the circumferential outer wall of the positioning ring through a connecting rod; the positioning ring is connected with the lower end of the tester lower chuck. When a compression test is carried out on pipe parts, the pipe fitting centering device can conveniently and reliably carry out centering operation on pipe fittings, the pipe fittings are prevented from deviating and overturning, and the centering precision of the pipe fittings is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of static testing, and in particular to an axial compression centering device for pipe parts, in particular to a pipe part compression centering device designed for compression testing of pipe parts. Background Art

[0002] With the continuous development of modern industry, pipe parts are increasingly used in various fields. From petrochemicals, aerospace to construction engineering, pipe parts (i.e. pipe fittings) have important tasks. However, in actual use, pipe parts are often subjected to various external forces, and compression force is a common force.

[0003] In order to ensure that pipe parts can work normally under compression load and ensure the safety and reliability of the project, it is particularly important to carry out compression tests on pipe parts.

[0004] At present, there are many types of pipe parts on the market, with different materials and great differences in their performance. In addition, with the continuous advancement of science and technology, the performance requirements for pipe parts are also constantly increasing. New materials and manufacturing processes are constantly emerging, and compression tests are needed to verify their feasibility and reliability. At the same time, compression tests can also provide data support for the design and optimization of pipe parts, and promote technological innovation and development in the pipe parts industry.

[0005] When performing compression tests on pipe parts, it is required to adopt the compression centering method of the pipe parts.

[0006] It should be noted that centering means that the central axis of the chuck of the testing machine (such as a compressor) is required to be in the same straight line as the central axis of the pipe part, which prevents the test piece (such as a pipe part) from being subjected to uneven force when compressed. The compression centering method is used for pipe parts to ensure that the test piece (such as a pipe part) is subjected to uniform force, avoid excessive or insufficient local stress, and make the stress in all parts of the cross section roughly equal. If the test piece is not centered during the test, it may cause uneven stress, which in turn causes unstable failure, affecting the accuracy of the test data and the observation of the cross-sectional shape.

[0007] However, the traditional compression centering method for pipe parts is to adjust by manual observation combined with calipers and micrometers, which has obvious disadvantages, as follows:

[0008] First, the accuracy of manual observation and adjustment is limited, and it is difficult to ensure completely accurate centering.

[0009] Second, the centering process is rather complicated and time-consuming, which affects the test efficiency.

[0010] Third, the experience and skill levels of different operators will also affect the results of the centering.

[0011] Therefore, there is an urgent need to develop a technology that can solve the above technical problems. Summary of the invention

[0012] The purpose of the present invention is to provide an axial compression centering device for pipe parts in view of the technical defects in the prior art.

[0013] To this end, the present invention provides an axial compression centering device for pipe parts, which includes an upper compression platform and a lower compression platform, as well as a guide mechanism and a positioning mechanism;

[0014] Wherein, the guide mechanism comprises a guide block, an outer ring, a guide post and a spring;

[0015] A positioning mechanism, comprising a positioning ring and a connecting rod;

[0016] Among them, the upper compression platform is located directly above the lower compression platform;

[0017] The top center position of the upper compression platform is connected to the upper clamp of the testing machine of the external testing machine;

[0018] The bottom center position of the lower compression platform is connected to the lower clamp of the testing machine of the external testing machine;

[0019] Among them, a plurality of guide blocks are placed on the top of the lower compression platform;

[0020] A plurality of guide blocks are disposed circumferentially on the inner side of an outer ring;

[0021] An accommodating cavity for placing the lower end of the test piece is formed between the inner side surfaces of the plurality of guide blocks;

[0022] The outer side surface of each guide block is provided with a radially distributed guide post;

[0023] Each guide pin sleeve has a helical spring;

[0024] The outer end of the guide post passes through the guide post through hole reserved on the outer ring;

[0025] The outer end of the spring is in tight contact with the inner wall of the outer ring;

[0026] Wherein, the two circumferential sides of the bottom of the outer ring are respectively connected to the circumferential outer wall of a positioning ring through a connecting rod;

[0027] The positioning ring is fixedly connected to the lower end of the lower clamp of the testing machine.

[0028] It can be seen from the technical solution provided by the present invention that, compared with the prior art, the present invention provides an axial compression centering device for pipe parts, which is scientifically designed. The present invention is applied in the process of compression testing pipe parts (i.e., pipe fittings). The present invention can conveniently and reliably perform centering (i.e., centering) operations on pipe parts, prevent the pipe fittings from being offset and flipped, and ensure the centering accuracy of the pipe fittings, which is beneficial to improving the overall efficiency of the compression test and reducing the test error, and has great practical significance.

[0029] In addition, the device of the present invention is an axial compression centering device for pipe parts based on a universal testing machine. It adopts a wedge block (i.e., a guide block) in combination with a spring and a guide column. When a force load is applied, the pipe is guided by the wedge block (i.e., a guide block). At the same time, the wedge block is used to always press the pipe through the spring, thereby preventing the pipe from shifting and flipping, effectively ensuring the centering accuracy of the pipe, improving the work efficiency of the test, and reducing the test error.

[0030] In addition, the centering method adopted by the present invention is a more accurate method for centering the axis of the pipe compression test, which is beneficial to improving the accuracy of the pipe compression test data and preventing the situation where the test accuracy is affected by large manual centering errors.

[0031] The present invention is designed for compression tests of pipe parts. It is difficult to accurately coincide the central axis of the pipe parts with the central axis of the testing machine (such as a compressor) during the compression test, so a compression centering device is designed for such parts. The central axis of the device of the present invention coincides with the central axis of the testing machine (such as a compressor), and under the action of pressure, the central axis of the pipe parts and the device are coincident through the guidance of the wedge block (i.e., the guide block), solving the problem of difficult centering of the pipe parts during compression tests. After testing, the scheme of the present invention can be reliably applied to pipe parts with a diameter of 3-80 mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of the working state of an embodiment of an axial compression centering device for a pipe part provided by the present invention Figure 1 (It is a schematic diagram of the front side);

[0033] Figure 2 A schematic diagram of the working state of an embodiment of an axial compression centering device for a pipe part provided by the present invention Figure 2 (It is a schematic diagram from the side);

[0034] Figure 3 Schematic diagram of the principle of an axial compression centering device for pipe parts provided by the present invention Figure 1 ;

[0035] Figure 4Schematic diagram of the principle of an axial compression centering device for pipe parts provided by the present invention Figure 2 ;

[0036] Figure 5 A three-dimensional assembly schematic diagram of an embodiment of an axial compression centering device for a pipe part provided by the present invention (i.e., a three-dimensional diagram after assembly);

[0037] Figure 6 A schematic diagram of a three-dimensional exploded structure of an embodiment of an axial compression centering device for a pipe part provided by the present invention;

[0038] Figure 7 A schematic diagram of the three-dimensional structure of an axial compression centering device for a pipe part provided by the present invention and a test piece (pipe part) that needs to be centering;

[0039] In the figure, 1-testing machine upper chuck, 2-upper compression platform, 3-spring, 4-guide column, 5-lower clamping block;

[0040] 6-locating ring, 7-lower chuck of testing machine, 8-lower compression platform, 9-connecting rod, 10-outer ring;

[0041] 11-guide block, 12-test piece, 13-upper clamping block. DETAILED DESCRIPTION

[0042] 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.

[0043] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0044] In the description of this patent, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "set" should be understood in a broad sense, for example, it can be fixedly connected or set, or it can be detachably connected or set, or connected or set in one piece. For ordinary technicians in this field, the specific meanings of the above terms in this patent can be understood according to specific circumstances.

[0045] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0046] See also Figures 1 to 7 The present invention provides an axial compression and centering device for pipe parts, which is an axial compression and centering device for pipe parts based on a universal testing machine. The device comprises: an upper compression platform 2 and a lower compression platform 8, as well as a guide mechanism and a positioning mechanism;

[0047] The guide mechanism includes a guide block 11, an outer ring 10, a guide post 4 and a spring 3;

[0048] A positioning mechanism, comprising a positioning ring 6 and a connecting rod 9;

[0049] Among them, the upper compression platform 2 is located directly above the lower compression platform 8;

[0050] The top center position of the upper compression platform 2 is connected to the upper chuck 1 of the external testing machine;

[0051] The bottom center position of the lower compression platform 8 is connected to the lower clamp 7 of the external testing machine;

[0052] Among them, a plurality of guide blocks 11 are placed on the top of the lower compression platform 8;

[0053] A plurality of guide blocks 11 are placed circumferentially on the inner side of an outer ring 10;

[0054] An accommodating cavity for placing the lower end of a test piece 12 (i.e., a pipe to be subjected to a compression test) is formed between the inner side surfaces of the plurality of guide blocks 11 (i.e., the side close to the central axis of the lower compression platform 8);

[0055] The outer side surface of each guide block 11 (i.e. the side away from the central axis of the lower compression platform 8) is provided with a radially distributed guide column 4;

[0056] Each guide post 4 is covered with a spiral spring 3;

[0057] The outer end of the guide post 4 passes through the guide post through hole reserved on the outer ring 10;

[0058] The outer end of the spring 3 (i.e., the end away from the central axis of the lower compression platform 8) is in tight contact with the inner wall of the outer ring 10;

[0059] The two circumferential sides of the bottom of the outer ring 10 are connected to the circumferential outer wall of a positioning ring 6 through a connecting rod 9 respectively;

[0060] The positioning ring 6 is fixedly connected to the lower end of the lower clamp 7 of the testing machine.

[0061] It should be noted that, in the present invention, the positioning ring 6 and the connecting rod 9 together form a positioning mechanism; the guide block 11, the outer ring 10, the guide column 4 and the spring 3 together form a guiding mechanism.

[0062] In the present invention, in a specific implementation, the cross-sectional shape of the upper compression platform 2 and the lower compression platform 8 is circular;

[0063] The overall shape of the outer ring 10 is annular.

[0064] In the present invention, in specific implementation, the two connecting rods 9 are axially symmetrically distributed.

[0065] In the present invention, the connecting rod 9 includes a first vertical section 901, a second vertical section 902, a first horizontal section 903 and a second horizontal section 904;

[0066] The upper end of the vertically distributed first vertical segment 901 is connected to the bottom of the outer ring 10;

[0067] The lower end of the first vertical section 901 is connected to the inner end of the horizontally distributed first horizontal section 903 (i.e., the end close to the central axis of the lower compression platform 8);

[0068] The outer end of the first horizontal section 903 (i.e., the end away from the central axis of the lower compression platform 8) is connected to the upper end of the second vertical section 902 distributed vertically;

[0069] The lower end of the second vertical section 902 is connected to the outer end of the horizontally distributed second horizontal section 904 (i.e., the end away from the central axis of the lower compression platform 8);

[0070] The inner end of the second horizontal section 904 (ie, the end close to the central axis of the lower compression platform 8 ) is connected to the circumferential outer wall of the positioning ring 6 .

[0071] In a specific implementation, the central axes of the first vertical segment 901, the second vertical segment 902, the first horizontal segment 903 and the second horizontal segment 904 are located on the same vertical plane;

[0072] In a specific implementation, the first horizontal segment 903 and the second horizontal segment 904 are distributed along the radial direction of the outer ring 10 .

[0073] In a specific implementation, the first vertical segment 901, the second vertical segment 902, the first horizontal segment 903 and the second horizontal segment 904 are integrally formed, and can be obtained by bending a straight metal rod multiple times.

[0074] In the present invention, in a specific implementation, the positioning ring 6 includes two semicircular rings;

[0075] Each semicircular ring is fixedly connected to the lower end of the lower clamp 7 of the testing machine through a fastening bolt. Specifically, the lower end of the lower clamp 7 of the testing machine has a threaded hole for threaded connection with the fastening bolt, and the semicircular ring has a bolt through hole. The fastening bolt passes through the bolt through hole and is threadedly connected to the threaded hole.

[0076] In the present invention, a plurality of guide blocks 11 are placed around the top of the lower compression platform 8 .

[0077] In the present invention, a plurality of guide blocks 11 surround and form an integral guide structure;

[0078] When the test piece 12 is not placed inside the integral guide structure (ie, the inclined surface of the guide block does not contact the test piece), the plurality of guide blocks 11 are connected in sequence, and the cross-sectional shape of the integral guide structure is a circular ring.

[0079] In the present invention, four guide blocks 11 are placed around the top of the lower compression platform 8;

[0080] In specific implementation, the top and bottom surfaces of the guide block 11 are smooth planes;

[0081] The outer side surface of the guide block 11 (i.e. the side away from the central axis of the lower compression platform 8) is a vertical plane;

[0082] The inner side surface of the guide block 11 (ie, the side close to the central axis of the lower compression platform 8 ) is an inclined surface, and the height of the inclined surface increases as the distance from the central axis of the lower compression platform 8 increases.

[0083] In specific implementation, the cross-sectional shape of the guide block 11 is a fan ring shape;

[0084] In a specific implementation, the radial cross-section of the guide block 11 is a right-angled trapezoid.

[0085] In a specific implementation, the four guide blocks 11 have exactly the same shape and structure, and are all wedge-shaped blocks.

[0086] In the present invention, the guide block 11 is a wedge-shaped structure, and its material is 45 steel.

[0087] In the present invention, the circumferential outer side surface of the guide block 11 is provided with radially distributed bosses;

[0088] The boss is provided with radially distributed threaded holes;

[0089] The threaded hole on the boss is threadedly connected to the inner end of the guide column 4;

[0090] The outer sides of the guide pillar 4 and the boss are covered with a spring 3.

[0091] It should be noted that the guide column 4 and the spring 3 can limit the movement direction of the guide block 11 to improve the centering accuracy.

[0092] It should be noted that, in the present invention, four identical guide blocks 11 can be placed on the top of the lower compression platform 8. The gaps inside the four guide blocks 11 are used to vertically penetrate the test piece 12 (i.e., the pipe fitting) that needs to be subjected to the compression test. The horizontal movement direction of the test piece 12 is guided by the guide blocks 11.

[0093] It should be noted that, in the present invention, a limiting device (i.e., spring 3) is provided on the guide column 4, and the limiting device is used to keep the center of the guide block 11 coincident with the central axis of the testing machine;

[0094] In the present invention, the outer ring 10 is kept coincident with the central axis of the testing machine through the positioning ring 6, and the clamping force is provided by the spring 3 during the compression operation.

[0095] In the present invention, in a specific implementation, a vertically distributed upper platform center connecting column 201 is provided at the top center position of the upper compression platform 2;

[0096] The original (ie, inherent) upper clamping block 13 at the lower end of the upper clamping head 1 of the testing machine is connected (ie, clamped and connected) to the central connecting column 201 of the upper platform.

[0097] It should be noted that, for the external testing machine, the original (i.e., inherent) upper clamping block 13 at the lower end of the upper chuck 1 of the testing machine specifically includes two upper clamping blocks 13 spaced apart, and the two upper clamping blocks 13 are located in an upper clamping block accommodating notch groove (the groove is open at the bottom and penetrates front to back, and has a cross-sectional shape of an inverted isosceles trapezoid) on the inner side of the lower end of the upper chuck 1 of the testing machine; the two upper clamping blocks 13 on the upper chuck 1 of the testing machine can move relative to each other to clamp or release an object placed in the gap between the two (e.g., the center connecting column 201 of the upper platform).

[0098] In the present invention, a vertically distributed lower platform center connecting column 801 is provided at the bottom center position of the upper and lower compression platforms 8;

[0099] The original (i.e., inherent) lower clamping block 5 at the upper end of the lower clamping head 7 of the testing machine is connected (i.e., clamped and connected) to the central connecting column 801 of the lower platform.

[0100] It should be noted that, for the external testing machine, the original (i.e., inherent) lower clamping block 5 at the upper end of the lower clamping head 7 of the testing machine specifically includes two spaced-apart lower clamping blocks 5, and the two lower clamping blocks 5 are located in a lower clamping block accommodating notch groove (the groove is open at the bottom and penetrates front to back, and the cross-sectional shape is an inverted isosceles trapezoid) provided on the inner side of the upper end of the lower clamping head 7 of the testing machine; the two lower clamping blocks 5 can move relative to each other to clamp or release an object placed in the gap between them (such as the central connecting column 801 of the lower platform).

[0101] In the present invention, in a specific implementation, the material of the guide column 4 is 45 steel, and the guide column 4 is connected to the guide block 11 through an external thread; the guide column 4 passes through the guide column through hole reserved in the outer ring 10 to perform a guiding function and can be used to limit the movement trajectory of the guide block 11.

[0102] In the present invention, in a specific implementation, the inner diameter of the spring 3 is 10 mm, and the inner diameter material of the spring 3 is 304 stainless steel;

[0103] In a specific implementation, the two ends of the spring 3 are respectively connected to the guide block 11 and the outer ring 10 for applying pressure so that the guide block 11 can always press the test piece 12 (ie, the pipe fitting) during the compression process.

[0104] In the present invention, in a specific implementation, the outer ring 10 is a ring with an inner diameter of 220 mm and an outer diameter of 240 mm;

[0105] The outer ring 10 is connected to the positioning ring 6 via a connecting rod 9 to ensure that the center axis of the guide block 11 coincides with the center axis of the testing machine.

[0106] In the present invention, in specific implementation, the testing machine is a compressor with mature existing technology and has been widely used, such as a universal compressor. Specifically, a universal testing machine with model DDL-200 produced by China Machinery Testing Equipment Co., Ltd. can be used to apply compression load to pipe fittings (i.e. pipe parts).

[0107] In the present invention, in a specific implementation, the central axis of the upper chuck 1 of the testing machine, the central axis of the upper compression platform 2, the central axis of the lower chuck 7 of the testing machine and the central axis of the lower compression platform 8, as well as the central axis of the upper clamp 13 and the central axis of the lower clamp 5 all coincide and are located on the same straight line.

[0108] In the present invention, in a specific implementation, the material of the positioning ring 6 is 45 steel and is composed of two semicircular rings;

[0109] The positioning ring 6 is connected to the lower chuck 7 of the testing machine by bolts, and is connected to the outer ring 10 by a connecting rod 9, and is used to ensure that the axis of the outer ring 10 coincides with the central axis of the upper chuck 1 of the testing machine, the central axis of the upper compression platform 2, the central axis of the lower chuck 7 of the testing machine and the central axis of the lower compression platform 8, and to ensure that the axis of the outer ring 10 coincides with the central axis of the test piece 12 connected to the testing machine through the upper clamp 13 and the lower clamp 5.

[0110] In the present invention, in a specific implementation, the connecting rod 9 is made of 45 steel, and its upper and lower ends are respectively connected to the outer ring 10 and the positioning ring 6 by welding to ensure that the central axis of the outer ring 10 coincides with the central axis of the positioning ring 6.

[0111] In the present invention, in a specific implementation, the top surface of the test piece 12 is in direct contact with the bottom surface of the upper compression platform 2 .

[0112] It should be noted that, for the present invention, since the bottom surface of the upper compression platform 2 is used to press against the top surface of the test piece 12, it can be suitable for applying compression loads to test pieces 2 (i.e., pipe parts) of multiple specifications and sizes.

[0113] In addition, for the present invention, considering that there will be errors when the upper compression platform 2 is connected and clamped with the upper chuck 1 of the testing machine through the clamp block (i.e. the upper clamp block), it is impossible to ensure that the upper compression platform 2 and the axis of the testing machine (i.e. the central axis of the upper chuck 1 of the testing machine) are completely coincident. For this reason, the present invention fixes the positioning ring 6 on the fixed shaft at the lower end of the testing machine (i.e. the lower chuck 7 of the testing machine), and the central axis of the positioning ring 6 directly coincides with the central axis of the testing machine to achieve precise positioning.

[0114] In order to more clearly understand the technical solution of the present invention, the working principle of the present invention is explained below.

[0115] According to the present invention, the test piece is guided by the spring, guide column, outer ring and guide block included in the guide mechanism to complete the centering.

[0116] In addition, the connecting rod and the positioning ring included in the positioning mechanism ensure that the central axis of the guide mechanism coincides with the central axis of the testing machine, thereby ensuring the accuracy of the centering.

[0117] The specific working process of the present invention is:

[0118] First, when the test is implemented, the axial compression centering device provided by the present invention is connected to the existing testing machine, and the reliability of the connection is checked, and whether the movement of the guide column 4 is smooth;

[0119] Then, the lower end of the test piece 12 is placed on the inclined surface inside the guide block 11, and the testing machine is turned on. The upper chuck 1 of the testing machine drives the upper compression platform 2 downward. The downward pressure applied causes the test piece 12 to move downward, and the guide block 11 approaches the outer ring 10 along the direction of the guide column 4. In this process, the presence of the spring 3 enables the guide block 11 to always press the test piece 12 to prevent it from turning over, until the test piece 12 falls to the top surface of the lower compression platform 8, completing the centering operation (that is, the central axis of the test piece coincides with the central axis of the testing machine).

[0120] Compared with the prior art, the axial compression centering device for pipe parts provided by the present invention has the following beneficial effects:

[0121] By means of the axial compression centering device for pipe parts provided by the present invention, when the pipe is subjected to a compression test, the central axis of the pipe as the test piece 12 is limited to coincide with the central axis of the outer ring 10 by the guide block 11, and the outer ring 10 ensures that its own central axis coincides with the central axis of the positioning ring 6 by the connecting rod 9; the positioning ring 6 is installed on the lower chuck 7 of the testing machine to ensure that its own central axis coincides with the central axis of the lower chuck 7 of the testing machine, thereby effectively ensuring the centering accuracy of the pipe during the compression operation, improving the work efficiency of the pipe parts in performing the existing conventional compression repeatability test, reducing the test error, and improving the credibility of the test results.

[0122] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An axial compression centering device for pipe parts, characterized in that: It comprises an upper compression platform (2) and a lower compression platform (8), as well as a guiding mechanism and a positioning mechanism; The guide mechanism comprises a guide block (11), an outer ring (10), a guide post (4) and a spring (3); A positioning mechanism, comprising a positioning ring (6) and a connecting rod (9); Wherein, the upper compression platform (2) is located directly above the lower compression platform (8); The top center position of the upper compression platform (2) is connected to the upper chuck (1) of the external testing machine; The bottom center position of the lower compression platform (8) is connected to the lower clamp (7) of the external testing machine; Wherein, a plurality of guide blocks (11) are placed on the top of the lower compression platform (8); A plurality of guide blocks (11) are disposed circumferentially on the inner side of an outer ring (10); An accommodating cavity for accommodating the lower end of the test piece (12) is formed between the inner side surfaces of the plurality of guide blocks (11); The outer side surface of each guide block (11) is provided with a radially distributed guide column (4); Each guide post (4) is sleeved with a spiral spring (3); The outer end of the guide post (4) passes through the guide post through hole reserved on the outer ring (10); The outer end of the spring (3) is in tight contact with the inner wall of the outer ring (10); The two circumferential sides of the bottom of the outer ring (10) are connected to the circumferential outer wall of a positioning ring (6) via a connecting rod (9) respectively; The positioning ring (6) is fixedly connected to the lower end of the lower clamp (7) of the testing machine.

2. The axial compression centering device for pipe parts according to claim 1, characterized in that: The cross-sectional shapes of the upper compression platform (2) and the lower compression platform (8) are circular; The overall shape of the outer ring (10) is a circular ring; The two connecting rods (9) are axially symmetrically distributed.

3. The axial compression centering device for pipe parts according to claim 1, characterized in that: A connecting rod (9), comprising a first vertical section (901), a second vertical section (902), a first horizontal section (903) and a second horizontal section (904); The upper end of the vertically distributed first vertical section (901) is connected to the bottom of the outer ring (10); The lower end of the first vertical section (901) is connected to the inner end of the horizontally distributed first horizontal section (903); The outer end of the first horizontal section (903) is connected to the upper end of the second vertical section (902) distributed vertically; The lower end of the second vertical section (902) is connected to the outer end of the horizontally distributed second horizontal section (904); The inner end of the second horizontal section (904) is connected to the circumferential outer wall of the positioning ring (6).

4. The axial compression centering device for pipe parts according to claim 3, characterized in that: The central axes of the first vertical section (901), the second vertical section (902), the first horizontal section (903) and the second horizontal section (904) are located on the same vertical plane; and / or, The first horizontal section (903) and the second horizontal section (904) are distributed along the radial direction of the outer ring (10); and / or, The first vertical section (901), the second vertical section (902), the first horizontal section (903) and the second horizontal section (904) are integrally formed.

5. The axial compression centering device for pipe parts according to claim 1, characterized in that: A positioning ring (6), comprising two semicircular rings; Each semicircular ring is fixedly connected to the lower end of the lower clamp (7) of the testing machine via a fastening bolt.

6. The axial compression centering device for pipe parts according to claim 1, characterized in that: A plurality of guide blocks (11) are placed around the top of the lower compression platform (8); A plurality of guide blocks (11) surround and form an integral guide structure; When no test piece (12) is placed inside the integral guide structure, a plurality of guide blocks (11) are connected in sequence, and the cross-sectional shape of the integral guide structure is a circular ring.

7. The axial compression centering device for pipe parts according to claim 1, characterized in that: Four guide blocks (11) are placed around the top of the lower compression platform (8); The four guide blocks (11) have the same shape and structure, and are all wedge-shaped blocks; and / or, The cross-sectional shape of the guide block (11) is a fan ring shape; and / or, The top and bottom surfaces of the guide block (11) are smooth planes; The outer side surface of the guide block (11) is a vertical plane; The inner side surface of the guide block (11) is an inclined surface, and the height of the inclined surface increases as the distance from the central axis of the lower compression platform (8) increases.

8. The axial compression centering device for a tubular part according to any one of claims 1 to 7, characterized in that: The circumferential outer side surface of the guide block (11) is provided with radially distributed bosses; The boss is provided with radially distributed threaded holes; The threaded hole on the boss is threadedly connected to the inner end of the guide column (4); The outer sides of the guide pillar (4) and the boss are covered with a spring (3).

9. The axial compression centering device for a tubular part according to any one of claims 1 to 7, characterized in that: A vertically distributed upper platform center connecting column (201) is provided at the top center of the upper compression platform (2); The upper clamping block (13) originally provided at the lower end of the upper clamping head (1) of the testing machine is connected to the central connecting column (201) of the upper platform; A lower platform center connecting column (801) distributed vertically is provided at the bottom center of the lower compression platform (8); The original lower clamping block (5) at the upper end of the lower clamping head (7) of the testing machine is connected to the central connecting column (801) of the lower platform.

10. The axial compression centering device for pipe parts according to claim 9, characterized in that: The central axis of the upper chuck (1) of the testing machine, the central axis of the upper compression platform (2), the central axis of the lower chuck (7) of the testing machine and the central axis of the lower compression platform (8), as well as the central axis of the upper clamping block (13) and the central axis of the lower clamping block (5) are all located on the same straight line.

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