Pipe fixing equipment and tensile test device comprising same

Abstract

The utility model discloses pipe fixing equipment and a tensile test device comprising the pipe fixing equipment, and relates to the technical field of pipe fixing equipment, the pipe fixing equipment comprises two plugs which are respectively used for being plugged into two ends of a pipe and used for supporting the inner wall of the pipe, one end of each plug is used for being plugged into the pipe, and the other end of each plug is used for being connected with a connecting rod. The connecting rod is provided with a welding area used for welding the end, close to the plug, of the connecting rod and the pipe into a whole. The connecting rod and the pipe are connected into a whole through the welding area, the original shape of the pipe is well kept, and the phenomenon that the root of the pipe, namely the clamped area of the pipe is fractured due to the fact that the root of the pipe is deformed due to stress concentration when the pipe which is high in strength, thin in pipe wall or large in outer diameter is clamped through a sleeve is avoided. And the pipe cannot be continuously clamped by the sleeve for subsequent operation. Compared with other connection modes, welding connection can better adapt to strain and expansion of the pipe in the environment of high temperature and the like, and firm fixing of the pipe is achieved.

Description

Technical Field

[0001] The utility model relates to the field of tensile test equipment, in particular to a pipe fixing device and a tensile test device including the pipe fixing device. Background Art

[0002] In the prior art, for small-sized metal pipes, the sleeve pressing method can be used. However, when the strength of the metal pipe is too high, the wall thickness is too thin, or the outer diameter size is too large, this method is not applicable. If the sleeve pressing method is used for tensile tests, due to the high strength or thin wall thickness of the metal pipe, local plastic deformation is likely to occur during the process of clamping the metal pipe by the sleeve, resulting in the fracture of the pipe root due to stress concentration and inability to perform subsequent operations such as tensile tests.

[0003] For example, the patent document CN110806348A includes a sleeve, a clamping cone, a top cone, a plug, and a connecting rod. One end inside the sleeve is a tapered opening and the other end is an internal thread; the clamping cone is in the shape of a frustum of a cone and has a threaded hole inside; the top cone has an external thread; the plug is used to plug into both ends of the metal pipe and support the pipe wall. Both ends of the metal pipe are respectively placed into the threaded holes of the clamping cone, the clamping cone is placed at the tapered opening inside the sleeve, and the top cone is screwed into the sleeve to press the clamping cone to clamp the metal pipe. The top cone is connected to the testing machine through a connecting rod. As can be seen from the above, this patent document clamps the metal pipe through the top cone and the pressing cone to perform tensile tests. However, it should be noted that due to the clamping forces of the top cone and the pressing cone on both ends of the metal pipe, compared with other regions of the metal pipe, the forces on both ends of the metal pipe are larger and prone to deformation. When this patent document is used for tensile tests of metal pipes with high strength, thin wall thickness, or large outer diameter size, both ends of the metal pipe will fracture due to stress concentration and cannot be fixed for subsequent operations.

[0004] Therefore, how to avoid the fracture of the pipe root due to stress concentration and the inability to be fixed for subsequent operations has become a technical problem that needs to be urgently solved by those skilled in the art. Summary of the Utility Model

[0005] The purpose of the utility model is to provide a pipe fixing device and a tensile test device including the pipe fixing device to solve the problems existing in the above prior art, avoid the problem that the pipe root fractures due to stress concentration and cannot be fixed for subsequent operations, and achieve reliable fixation of the pipe.

[0006] To achieve the above purpose, the utility model provides the following solutions:

[0007] The present utility model provides a pipe fixing device, which includes two plugs respectively used for being inserted into both ends of a pipe and for supporting the inner wall of the pipe. One end of the plug is used for being inserted into the pipe, and the other end of the plug is used for being connected to a connecting rod. A welding area is provided on the connecting rod for welding the end of the connecting rod close to the plug and the pipe into one body.

[0008] Preferably, the diameter of the largest end of the plug is smaller than the inner diameter of the pipe.

[0009] Preferably, the plug is a tapered variable-diameter plug, and the largest end of the plug is connected to the connecting rod.

[0010] Preferably, the plug is in a bullet shape or a frustum shape.

[0011] Preferably, the connecting rod is a telescopic rod with adjustable length.

[0012] Preferably, the telescopic rod includes a first connecting rod and a second connecting rod;

[0013] The first connecting rod is slidably connected to the second connecting rod, and the telescopic rod further includes a limiting member for axially positioning the second connecting rod and the first connecting rod;

[0014] Alternatively, the first connecting rod is threadedly connected to the second connecting rod.

[0015] Preferably, the pipe is sleeved outside the connecting rod, and the inner diameter of the pipe is the same as the diameter of the connecting rod; the welding area includes a welding ring provided outside the connecting rod.

[0016] The present utility model also provides a tensile test device, which includes the pipe fixing device, and the end of the connecting rod far from the plug is used for being connected to a testing machine.

[0017] Preferably, the tensile test device further includes a high-temperature furnace, and when a tensile test is performed, the pipe is located inside the high-temperature furnace.

[0018] Preferably, when a tensile test is performed, a plurality of temperature sensors for detecting the temperature of the pipe are arranged along the axial direction of the pipe.

[0019] The present utility model has achieved the following technical effects compared with the prior art:

[0020] The utility model connects the connecting rod and the pipe through the welding area, which better maintains the original shape of the pipe, and avoids the problem that when clamping a pipe with a large clamping strength, a thin pipe wall or a large outer diameter size through a sleeve, the root of the pipe is deformed due to stress concentration, resulting in the fracture of the root of the pipe, that is, the area where the pipe is clamped, and the pipe cannot be continuously clamped by the sleeve for subsequent operations; compared with other connection methods, the welding connection can better adapt to the strain and expansion of the pipe in environments such as high temperature, and realizes the reliable fixation of the pipe. Brief Description of the Drawings

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings described below are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0022] Figure 1 It is a schematic structural diagram of the plug at one end of the pipe and the connecting rod;

[0023] Figure 2 It is a schematic structural diagram of the tensile test device;

[0024] Figure 3 It is a schematic cross-sectional view of the pipe in the high-temperature furnace;

[0025] Among them, 1. Pipe; 2. Plug; 3. Connecting rod; 4. First connecting rod; 5. Second connecting rod; 6. Welding area; 7. High-temperature furnace; 8. Thermocouple. Detailed Embodiments

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present utility model with reference to the drawings in the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, rather than all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present utility model.

[0027] In order to make the above objects, features, and advantages of the present utility model more obvious and understandable, the present utility model will be further described in detail below with reference to the drawings and specific embodiments.

[0028] Such as Figures 1 - 3As shown in the figure, the utility model discloses a pipe fixing device, which includes two plugs 2 respectively used for inserting into both ends of the pipe 1 and supporting the inner wall of the pipe 1. One end of the plug 2 is used for inserting into the pipe 1, and the other end of the plug 2 is used for connecting with the connecting rod 3. A welding area 6 is provided on the connecting rod 3 for welding the end of the connecting rod 3 close to the plug 2 and the pipe 1 into one body.

[0029] In the utility model, the connecting rod 3 and the pipe 1 are connected into one body through the welding area 6, which better maintains the original shape of the pipe 1, and avoids the problem that when clamping a pipe 1 with a relatively large clamping strength, a relatively thin pipe wall or a relatively large outer diameter size with a casing, the root of the pipe 1 is deformed due to stress concentration, resulting in the fracture of the root of the pipe 1, that is, the area of the pipe 1 clamped by the casing, and the pipe 1 cannot be continuously clamped by the casing for subsequent operations; compared with other connection methods, the welding connection can better adapt to the strain and expansion of the pipe 1 in environments such as high temperature, and realizes the reliable fixation of the pipe 1.

[0030] When the pipe fixing device is used for the tensile test of the pipe 1, the connecting rod 3 and the pipe 1 are connected into one body by welding, avoiding the problem that when conducting a tensile test on a pipe 1 with a relatively large strength, a relatively thin pipe wall or a relatively large outer diameter size, due to clamping the pipe 1 with a casing, the stress concentration at the root of the pipe 1 causes deformation and the root of the pipe 1 fractures, resulting in the inability to continue the tensile test of the pipe 1.

[0031] It should be noted that the plug 2 in the utility model has various setting forms, but no matter which form of the plug 2, the plug 2 does not prevent the deformation within the gauge length. The gauge length refers to the length of the parallel part used to measure the elongation of the pipe 1 at any moment when the pipe 1 is used for the tensile test. The plug 2 does not prevent the deformation within the gauge length, which means that during the tensile process of the pipe 1, the gauge length will gradually increase (the pipe 1 is stretched), and during the increase of the gauge length, the plug 2 will not affect the deformation (stretching) of the pipe 1.

[0032] Specifically, the plug 2 can be a gradually variable diameter plug 2 or a constant diameter plug 2. If it is a step - type variable diameter plug 2, when the pipe fixing device is used for the tensile test, the diameter mutation part of the plug 2 will easily fracture due to stress concentration, resulting in the inability to continue fixing the pipe 1 and the smooth progress of the tensile test being affected. And no matter which type of plug 2, the diameter of the largest end of the plug 2 is smaller than the inner diameter of the pipe 1, so that the plug 2 can be inserted into the pipe 1 to support the inner wall of the pipe 1; however, the diameter of the plug 2 cannot be too small, to prevent the problem that after the pipe 1 and the connecting rod 3 are welded together, the post - welding horizontal and vertical cannot be guaranteed when the pipe fixing device is used for the tensile test, and at the same time avoid the problem that when the pipe fixing device is used for the tensile test, the deformation is concentrated at the plug 2, making it difficult to smoothly conduct the tensile test. Specifically, the diameter of the largest end of the plug 2 is 0 - 0.05 mm.

[0033] The welding area 6 includes a welding ring provided outside the connecting rod 3. The welding ring and one end of the pipe 1 close to the plug 2 can be welded together through welding processes such as laser welding. By using laser welding, the heat input is reduced and the heat influence is lowered. The pipe 1 mentioned in the present utility model is a hollow pipe 1.

[0034] When the plug 2 is a tapered variable-diameter plug 2, the plug 2 can specifically be in the shape of a bullet head or a frustum of a cone. By the gradually changing diameter, the problem of stress concentration and fracture of the plug 2 is avoided, so as to ensure that when the pipe fixing device is used for a tensile test, the tensile test can proceed smoothly.

[0035] Such as Figures 1 - 3 As shown, in the present utility model, the connecting rod 3 is a telescopic rod with adjustable length. When the pipe fixing device is used for a tensile test, the position or length of the pipe 1 for the tensile test in the high-temperature furnace 7 can be adjusted through the telescopic rod, so as to ensure that the tensile test of the pipe 1 can proceed smoothly in a high-temperature environment; and the telescopic rod with adjustable length can be applicable to pipes 1 of various lengths.

[0036] Specifically, in the present utility model, the telescopic rod includes a first connecting rod 4 and a second connecting rod 5; the first connecting rod 4 is slidably connected to the second connecting rod 5, and the telescopic rod further includes a limiting member for axially positioning the second connecting rod 5 and the first connecting rod 4. The sliding connection is specifically that the second connecting rod 5 is sleeved outside the first connecting rod 4, the inner diameter of the second connecting rod 5 is greater than the diameter of the first connecting rod 4, or the first connecting rod 4 is sleeved outside the second connecting rod 5. At this time, the inner diameter of the first connecting rod 4 is greater than the diameter of the second connecting rod 5, and a chute and a slider can also be provided between the second connecting rod 5 and the first connecting rod 4 to improve the stability of the telescopic movement of the telescopic rod. The limiting member can specifically be a pin rod. At this time, pin holes corresponding to each other in position are provided on both the second connecting rod 5 and the first connecting rod 4, and the pin holes are matched with the pin rod, so that after the second connecting rod 5 moves relative to the first connecting rod 4 to the required position, the pin rod is inserted and passes through the pin holes on the second connecting rod 5 and the first connecting rod 4, and the positions of the second connecting rod 5 and the first connecting rod 4 can be limited, so that the connecting rod 3 can achieve stable adjustment of the length, and thus accurately adjust the position of the pipe 1.

[0037] Or, the first connecting rod 4 and the second connecting rod 5 may not achieve length adjustment through the above structure. For example, the first connecting rod 4 is threadedly connected to the second connecting rod 5. Specifically, a connecting groove with internal threads can be opened inside the first connecting rod 4, and an external thread adapted to the connecting groove is provided on the outside of the second connecting rod 5. When the pipe fixing device is used for a tensile test, one end of the first connecting rod 4 away from the second connecting rod 5 is used to connect to the testing machine, and one end of the second connecting rod 5 away from the first connecting rod 4 is used to connect to the plug 2.

[0038] Alternatively, a connection groove with internal threads may also be provided inside the second connecting rod 5, and an external thread adapted to the connection groove is provided on the outer side of the first connecting rod 4.

[0039] In the present utility model, the pipe 1 is sleeved on the outer side of the connecting rod 3, and the inner diameter of the pipe 1 is the same as the diameter of the connecting rod 3. This enables the pipe 1 to be smoothly connected to the connecting rod 3 as a whole through the welding area 6.

[0040] Furthermore, the present utility model also provides a tensile test device. The tensile test device includes a pipe fixing device, and one end of the connecting rod 3 away from the plug 2 is used to be connected to a testing machine. By connecting one end of the connecting rod 3 away from the plug 2 to the testing machine, the pipe 1 fixed by the pipe fixing device can smoothly carry out a tensile test.

[0041] Further, the tensile test device in the present utility model further includes a high-temperature furnace 7, and when a tensile test is carried out, the pipe 1 is located inside the high-temperature furnace 7, and the pipe 1 is specifically located at the center inside the high-temperature furnace 7 to ensure that the tensile test of the pipe 1 is carried out in a high-temperature environment. And at this time, the connecting rod 3 is located inside the high-temperature furnace 7. Thus, when both ends of the connecting rod 3 of the pipe 1 are located inside the high-temperature furnace 7, the pipe 1 must also be located inside the high-temperature furnace 7.

[0042] Furthermore, when a tensile test is carried out, a plurality of temperature sensors for detecting the temperature of the pipe 1 are arranged along the axial direction of the pipe 1. The temperature change of the pipe 1 is accurately detected by the above temperature sensors to ensure that the tensile test of the pipe 1 is carried out in a high-temperature environment. The temperature sensor may specifically be a thermocouple 8.

[0043] In addition, the present utility model also provides a method using the above tensile test device, including the following steps:

[0044] 1) Measure the dimensions of the machined metal pipe integral pipe test piece, calculate the original cross-sectional area S0 (mm 2 ), and mark the original gauge length L0 (mm);

[0045] 2) Select a connecting rod 3 with a corresponding specification according to needs and install it on the testing machine (the testing machine refers to a tensile testing machine). During the test, adjust the length of the connecting rod 3 to ensure that the test part of the metal pipe integral pipe test piece is in the central part of the high-temperature furnace 7. Both ends of the metal pipe integral pipe test piece are inserted into the plug 2 and sleeved on the connecting rod 3. Through laser welding, the connecting rod 3 is connected to the pipe 1, and both ends of the metal pipe 1 integral pipe test piece are connected in the same way; the size of the connecting rod 3 is d (inner diameter of the pipe), the size of the plug 2 is smaller than d and is bullet-shaped, and the plug 2 is slidably fitted into the metal pipe integral pipe test piece without deforming the metal pipe integral pipe test piece. The specimen length between the inner ends of the two plugs 2 should not be less than 50 mm; the connecting rod 3 is inside the high-temperature furnace 7;

[0046] 3) Hang one end of the integral pipe test piece of the metal pipe 1 on the testing machine through the connecting rod 3, calibrate the test force, and then connect and install the other end on the testing machine through the connecting rod 3;

[0047] 4) By adjusting the length of the connecting rod 3, ensure that the test part of the integral pipe test piece of the metal pipe is in the central part of the high-temperature furnace 7. The thermocouples 8 correspond to the upper, middle, and lower three parts of the parallel section of the integral pipe test piece of the metal pipe respectively to ensure accurate temperature. Click the load zero-holding function and start heating;

[0048] 5) The heating rate should not be too high to avoid temperature overshoot. After heating to the specified test temperature, start heat preservation. The heat preservation time is at least 20 min, and start the high-temperature tensile test. Select the following parameters for the test rate: before yielding, select the moving rate of the crossbeam to be 0.5 mm / min - 0.9 mm / min, and after yielding, select the moving rate of the crossbeam to be 1.5 mm / min - 3 mm / min; the testing machine automatically collects and records the test data; when the integral pipe test piece of the metal pipe is broken, according to the recorded yield force value F p 0.2 (kN), maximum force value F m (kN), calculate the yield strength R p 0.2 (MPa), tensile strength R m (MPa) according to the formula; the formula is as follows: R p 0.2 = F p 0.2 / S0; R m = F m / S0, then measure the gauge length L u (mm) to calculate the elongation A (%), and the formula is as follows: A = (L u - L0) / L0.

[0049] In the present utility model, specific examples are used to elaborate on the principle and implementation manner of the present utility model. The description of the above embodiments is only used to help understand the method and its core idea of the present utility model; at the same time, for those of ordinary skill in the art, based on the idea of the present utility model, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present utility model.

Claims

1. A pipe fixing device, characterized in that: It comprises two plugs which are respectively used to be inserted into the two ends of the pipe and to support the inner wall of the pipe. One end of the plug is used to be inserted into the pipe, and the other end of the plug is used to be connected to a connecting rod. The connecting rod is provided with a welding area for welding one end of the connecting rod close to the plug to the pipe as a whole.

2. The pipe fixing device according to claim 1, characterized in that: The diameter of the largest end of the plug is smaller than the inner diameter of the tube.

3. The pipe fixing device according to claim 2, characterized in that: The plug is a gradually changing diameter plug, and the largest end of the plug is connected to the connecting rod.

4. The pipe fixing device according to claim 3, characterized in that: The plug is in a bullet shape or a truncated cone shape.

5. The pipe fixing device according to claim 1, characterized in that: The connecting rod is a telescopic rod with adjustable length.

6. The pipe fixing device according to claim 5, characterized in that: The telescopic rod comprises a first connecting rod and a second connecting rod; The first connecting rod is slidably connected to the second connecting rod, and the telescopic rod further comprises a stopper for axially positioning the second connecting rod and the first connecting rod; Alternatively, the first connecting rod is threadedly connected to the second connecting rod.

7. The pipe fixing device according to claim 1, characterized in that: The pipe is sleeved on the outside of the connecting rod, and the inner diameter of the pipe is the same as the diameter of the connecting rod; the welding area includes a welding ring arranged outside the connecting rod.

8. A tensile testing device, characterized in that: The tensile testing device comprises the pipe fixing apparatus according to any one of claims 1 to 7, and the end of the connecting rod away from the plug is used for connecting to a testing machine.

9. The tensile testing device according to claim 8, characterized in that: The tensile testing device further comprises a high temperature furnace, and when the tensile test is performed, the pipe is located in the high temperature furnace.

10. The tensile testing device according to claim 8, characterized in that: When the tensile test is performed, a plurality of temperature sensors for detecting the temperature of the pipe are arranged along the axial direction of the pipe.

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