Expanded connection quality detection device and detection method for double-layer pipe

Abstract

The invention provides a double-layer pipe expanded connection quality detection device and detection method, and relates to the technical field of double-layer pipe preparation, the double-layer pipe expanded connection quality detection device comprises a first drawing piece, and a to-be-detected double-layer pipe is used for sleeving the outer peripheral wall of the first drawing piece; wherein the first end of the first drawing piece is provided with a first abutting part which is used for abutting against the end face of an inner-layer pipe at the first end of the to-be-tested double-layer pipe; the to-be-tested double-layer pipe is used for being arranged on the inner circumferential wall of the second drawing piece in a sleeving manner; the first end of the second drawing piece is provided with a second abutting part used for abutting against the outer-layer pipe end face of the second end of the to-be-tested double-layer pipe. Wherein the inner-layer pipe and the outer-layer pipe of the double-layer pipe to be detected are drawn in opposite directions, and expanded connection quality detection is carried out. The double-layer pipe expanding connection quality detection is carried out through the double-layer pipe expanding connection quality detection device, it is ensured that the double-layer pipe with the good expanding connection quality is subjected to bending forming, and relative sliding of the inner-layer pipe and the outer-layer pipe in the bending process is avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of double-layer pipe preparation, and particularly relates to a double-layer pipe expansion joint quality detection device and a detection method. Background Art

[0002] In a pipeline system, once a crack or fracture occurs in a pipeline, it will cause major safety accidents. Double-layer composite metal pipes can effectively provide "anti-leakage" protection for media such as energy transmission, and are new and important structural parts for improving the reliability of equipment.

[0003] In the forming of a double-layer pipe, the spatial bending configuration of the inner and outer (layer) pipes must be considered, making its manufacturing difficulty far exceed traditional methods. Therefore, the inner high-pressure forming method is used to expand the inner layer pipe, so that the inner layer pipe is attached to the outer layer pipe and continues to expand to reach the required size, obtaining a double-layer pipe.

[0004] In practical applications, when bending a double-layer pipe, in order to ensure the quality of the bent product, it is necessary to ensure a high expansion joint quality of the double-layer pipe to avoid relative sliding of the inner and outer pipes during bending. Therefore, it is necessary to detect the expansion joint quality of the double-layer pipe before bending. However, there is a lack of a detection device and a detection method for the expansion joint quality of double-layer pipes in the prior art. Summary of the Invention

[0005] Therefore, the present invention provides a double-layer pipe expansion joint quality detection device and a detection method to solve the lack of a detection device and a detection method for the expansion joint quality of double-layer pipes in the prior art.

[0006] To solve the above problems, the present invention provides a double-layer pipe expansion joint quality detection device, and the double-layer pipe expansion joint quality detection device includes:

[0007] A first pulling member, and a double-layer pipe to be measured is sleeved on the outer peripheral wall of the first pulling member; wherein, a first abutting portion is provided at the first end of the first pulling member for abutting against the end face of the inner layer pipe at the first end of the double-layer pipe to be measured.

[0008] A second pulling member, and a double-layer pipe to be measured is sleeved on the inner peripheral wall of the second pulling member; a second abutting portion is provided at the first end of the second pulling member for abutting against the end face of the outer layer pipe at the second end of the double-layer pipe to be measured.

[0009] Wherein, the double-layer pipe to be measured is clamped between the outer peripheral wall of the first pulling member and the inner peripheral wall of the second pulling member through the first pulling member and the second pulling member, so as to perform opposite-direction pulling on the inner layer pipe and the outer layer pipe of the double-layer pipe to be measured for expansion joint quality detection.

[0010] Further, the first pulling member is in a rod-like structure.

[0011] Further, the first abutting portion is a first stepped structure provided at the first end of the first pulling member; wherein, the stepped surface of the first stepped structure is used to abut against the end surface of the inner layer tube at the first end of the double-layer tube to be measured;

[0012] Preferably, the height h of the stepped surface of the first stepped structure 1 is less than or equal to the thickness of the inner layer tube in the double-layer tube to be measured; More preferably, the height h of the stepped surface of the first stepped structure 1 is greater than or equal to half of the thickness of the inner layer tube in the double-layer tube to be measured;

[0013] Preferably, the first stepped structure is arranged in a circle around the first end of the first pulling member;

[0014] Preferably, the first abutting portion and the first pulling member are of an integral structure.

[0015] Further, the second pulling member is of a tubular structure.

[0016] Further, the second abutting portion is a second stepped structure provided at the second end of the second pulling member; wherein, the stepped surface of the second stepped structure is used to abut against the end surface of the outer layer tube at the second end of the double-layer tube to be measured;

[0017] Preferably, the height h of the stepped surface of the second stepped structure 2 is less than or equal to the thickness of the outer layer tube in the double-layer tube to be measured; More preferably, the height h of the stepped surface of the second stepped structure 2 is greater than or equal to half of the thickness of the outer layer tube in the double-layer tube to be measured;

[0018] Preferably, the second stepped structure is arranged in a circle around the first end of the second pulling member;

[0019] Preferably, the second abutting portion and the second pulling member are of an integral structure.

[0020] Further, the first pulling member includes a first end, a second end, and a main body portion located between the first end and the second end;

[0021] The first end of the first pulling member is a frustum-shaped structure with one end large and the other end small; wherein, the large end portion of the frustum-shaped structure is connected to the main body portion; the small end portion of the frustum-shaped structure is the end portion of the first end of the first pulling member;

[0022] Preferably, the cross-sectional area of the large end portion of the frustum-shaped structure is larger than the cross-sectional area of the main body portion, so that a stepped surface is formed by the large end portion relative to the main body portion to serve as the first abutting portion;

[0023] Preferably, the first pulling member is of an integral structure.

[0024] Furthermore, the expansion joint quality detection device for the double-layer tube further includes:

[0025] A first pulling bolt connected to the second end of the first pulling member, where the second end and the first end of the first pulling member are opposite ends;

[0026] A second pulling bolt connected to the second end of the second pulling member, where the second end and the first end of the second pulling member are opposite ends;

[0027] Preferably, a first connection structure is provided at the second end of the first pulling member for connecting the first pulling bolt. Preferably, when the first pulling member is a rod-shaped structure, the first connection structure is a connection groove provided at the second end of the first pulling member; the first pulling bolt is threadedly connected to the connection groove;

[0028] Preferably, a second connection structure is provided at the second end of the second pulling member for connecting the second pulling bolt. Preferably, when the second pulling member is a tubular structure, the second connection structure is a thread provided at the second end of the second pulling member; the second pulling bolt is connected to the second pulling member through the thread;

[0029] Preferably, the first pulling bolt is used to connect to a tensile testing machine; the second pulling bolt is used to connect to a tensile testing machine.

[0030] On the other hand, the present invention provides a method for detecting the expansion joint quality of a double-layer tube, which uses the expansion joint quality detection device for the double-layer tube described in any one of the above to detect the expansion joint quality of the double-layer tube to be tested.

[0031] Furthermore, the method for detecting the expansion joint quality of the double-layer tube includes the following steps:

[0032] Step 1): Sleeve the double-layer tube to be tested on the outer peripheral wall of the first pulling member so that the first abutting portion on the first pulling member abuts against the inner tube end face of the first end of the double-layer tube to be tested; sleeve the double-layer tube to be tested on the inner peripheral wall of the second pulling member so that the second abutting portion on the second pulling member abuts against the outer tube end face of the second end of the double-layer tube to be tested;

[0033] Step 2): Pull the first pulling member in a direction away from the first end of the first pulling member and pull the second pulling member in a direction away from the first end of the second pulling member to perform opposite-direction pulling on the inner tube and the outer tube of the double-layer tube to be tested, and obtain the expansion joint quality detection result of the double-layer tube to be tested according to the magnitude of the pulling force during the pulling process.

[0034] Further, the double-layer tube to be measured is prepared by the following method:

[0035] The outer layer tube is sleeved outside the inner layer tube, and the inner layer tube is filled with liquid to expand the inner layer tube, and the outer wall of the inner layer tube fits against the inner wall of the outer layer tube.

[0036] The expansion joint quality detection device and detection method for a double-layer tube provided by the present invention have the following beneficial effects:

[0037] 1. The present invention provides an expansion joint quality detection device for a double-layer tube, including: a first pulling member, and the double-layer tube to be measured is sleeved on the outer peripheral wall of the first pulling member; wherein, a first abutting portion is provided at the first end of the first pulling member for abutting against the end face of the inner layer tube at the first end of the double-layer tube to be measured; a second pulling member, and the double-layer tube to be measured is sleeved on the inner peripheral wall of the second pulling member; a second abutting portion is provided at the first end of the second pulling member for abutting against the end face of the outer layer tube at the second end of the double-layer tube to be measured; wherein, the double-layer tube to be measured is clamped between the outer peripheral wall of the first pulling member and the inner peripheral wall of the second pulling member through the first pulling member and the second pulling member to perform opposite-direction pulling on the inner layer tube and the outer layer tube of the double-layer tube to be measured for expansion joint quality detection; the expansion joint quality of the double-layer tube is detected by the above expansion joint quality detection device for the double-layer tube, and it is ensured that the double-layer tube with better expansion joint quality is bent, so as to avoid relative sliding between the inner and outer layer tubes during bending, thereby ensuring the quality of the bent product.

[0038] 2. Further, the height h of the step surface of the first step structure in the present invention 1 is less than or equal to the thickness of the inner layer tube in the double-layer tube to be measured and greater than or equal to half of the thickness of the inner layer tube in the double-layer tube to be measured; the height h of the step surface of the second step structure 2 is less than or equal to the thickness of the outer layer tube in the double-layer tube to be measured and greater than or equal to half of the thickness of the outer layer tube in the double-layer tube to be measured; through the above settings, on the one hand, it is convenient to apply the pulling force, and on the other hand, it can avoid the contact between the first end of the mandrel and the outer layer tube during the pulling process, thereby ensuring the smooth progress of the pulling process.

[0039] 3. On the other hand, the present invention provides a method for detecting the expansion joint quality of a double-layer tube, which uses the expansion joint quality detection device of any one of the above, and includes the following steps: Step 1) sleeving the double-layer tube to be tested outside the mandrel, so that the inner tube end face of the first end of the double-layer tube to be tested abuts against the side face of the first step; Step 2) sleeving the bushing outside the double-layer tube to be tested, so that the outer tube end face of the second end of the double-layer tube to be tested abuts against the side face of the second step; Step 3) pulling the mandrel in the direction of the second end of the mandrel and pulling the bushing in the direction of the second end of the bushing, and obtaining the expansion joint quality detection result of the double-layer tube to be tested according to the magnitude of the pulling force during the pulling process; Based on the above method, it can be used to select double-layer tubes with higher expansion joint quality for bending forming, thereby avoiding the relative sliding of the inner and outer tubes during bending and ensuring the quality of the bent forming product. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. The drawings in the following description are only exemplary, and for those of ordinary skill in the art, without creative efforts, other implementation drawings can be obtained by extending according to the provided drawings.

[0041] Figure 1 is the process flow chart of the preparation process of the double-layer tube of the present invention; wherein: a is the assembly schematic diagram of the outer tube and the inner tube; b is the schematic diagram of the inner tube fitting the outer tube; c is the schematic diagram of the outer tube fitting the mold;

[0042] Figure 2 is the assembly structure diagram of the expansion joint quality detection device of the double-layer tube of the present invention;

[0043] Figure 3 is the assembly flow chart of the expansion joint quality detection device of the double-layer tube of the present invention; wherein: a is the assembly schematic diagram of the mandrel and the double-layer tube to be tested; b is the assembly schematic diagram of the bushing; c is the assembly schematic diagram of the mandrel pulling bolt and the bushing pulling;

[0044] Figure 4 a and 4b are respectively the schematic diagrams of the expansion joint quality detection results of the first double-layer tube to be tested and the second double-layer tube to be tested in Experimental Example 1 of the present invention;

[0045] Figure 5 is the schematic diagram of the expansion joint quality detection result of the double-layer tube in Experimental Example 2 of the present invention;

[0046] Figure 6 is the bending forming schematic diagram of the double-layer tube in Experimental Example 2 of the present invention;

[0047] Figure 7 is Figure 3 the partial enlarged view of a;

[0048] Figure 8 is Figure 3 a partial enlarged view of b;

[0049] The reference numerals in the drawings are:

[0050] 1, inner layer tube; 2, outer layer tube; 3, mold; 4, first drawing part; 5, second drawing part; 6, first drawing bolt; 7, second drawing bolt. Specific embodiments

[0051] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. The drawings in the following description are only exemplary. For those of ordinary skill in the art, without creative efforts, other implementation drawings can be obtained based on the provided drawings.

[0052] During the bending process of the double-layer tube, if the expansion joint quality is not characterized and measured, the phenomenon of slippage may occur between the inner layer tube and the outer layer tube due to the low expansion joint quality. Therefore, the present invention provides a device and method for detecting the expansion joint quality of a double-layer tube, which can be used as a determination basis for the inner and outer layer tubes of the double-layer tube not to undergo relative displacement during bending forming at a specific bending radius according to the detection result of the expansion joint quality of the double-layer tube.

[0053] The present invention will be described below through examples as follows:

[0054] Example 1

[0055] On the one hand, as Figure 2 shown, this embodiment provides a device for detecting the expansion joint quality of a double-layer tube. The device for detecting the expansion joint quality of a double-layer tube includes:

[0056] A first drawing part 4, and the double-layer tube to be tested is sleeved on the outer peripheral wall of the first drawing part 4; wherein, a first abutting part is provided at the first end of the first drawing part 4 for abutting against the end face of the inner layer tube 1 at the first end of the double-layer tube to be tested; a second drawing part 5, and the double-layer tube to be tested is sleeved on the inner peripheral wall of the second drawing part 5; a second abutting part is provided at the first end of the second drawing part 5 for abutting against the end face of the outer layer tube 2 at the second end of the double-layer tube to be tested;

[0057] Among them, the double-layer tube to be tested is clamped between the outer peripheral wall of the first drawing part 4 and the inner peripheral wall of the second drawing part 5 through the first drawing part 4 and the second drawing part 5, so as to realize the opposite-direction drawing of the inner layer tube and the outer layer tube of the double-layer tube to be tested and perform the expansion joint quality detection.

[0058] The expansion joint quality detection device for the double-layer pipe provided in this embodiment can judge the expansion joint quality of the double-layer pipe by the magnitude of the pulling force, so as to select the double-layer pipe with higher expansion joint quality for bending forming, thereby avoiding the relative sliding of the inner and outer pipes during bending and ensuring the quality of the bent forming product.

[0059] Embodiment 2

[0060] Preferably, this embodiment provides an expansion joint quality detection device for a double-layer pipe. Compared with Embodiment 1, as Figure 3 shown, this embodiment further designs the first pulling member, the second pulling member, the first abutting portion and the second abutting portion as follows:

[0061] The first pulling member 4 is in a rod-like structure; the first abutting portion is a first stepped structure provided at the first end of the first pulling member 4; wherein, the stepped surface of the first stepped structure is used to abut against the end surface of the inner pipe 1 at the first end of the double-layer pipe to be measured; the height h of the stepped surface of the first stepped structure 1 is less than or equal to the thickness of the inner pipe 1 in the double-layer pipe to be measured and greater than or equal to half of the thickness of the inner pipe 1 in the double-layer pipe to be measured; the first stepped structure is arranged in a circle around the first end of the first pulling member 4; the first abutting portion and the first pulling member 4 are of an integral structure, see Figure 7 ;

[0062] The second pulling member 5 is in a tubular structure; the second abutting portion is a second stepped structure provided at the second end of the second pulling member 5; wherein, the stepped surface of the second stepped structure is used to abut against the end surface of the outer pipe 2 at the second end of the double-layer pipe to be measured; the height h of the stepped surface of the second stepped structure 2 is less than or equal to the thickness of the outer pipe 2 in the double-layer pipe to be measured and greater than or equal to half of the thickness of the outer pipe 2 in the double-layer pipe to be measured; the second stepped structure is arranged in a circle around the first end of the second pulling member 5; the second abutting portion and the second pulling member 5 are of an integral structure, see Figure 8 。

[0063] In addition, the first pulling member 4 includes a first end, a second end and a main body portion located between the first end and the second end; the first end of the first pulling member is in a frustum-like structure with one end large and the other end small; wherein, the large end portion of the frustum-like structure is connected to the main body portion; the small end portion of the frustum-like structure is the end portion of the first end of the first pulling member; preferably, the cross-sectional area of the large end portion of the frustum-like structure is larger than the cross-sectional area of the main body portion, so that a stepped surface is formed by the large end portion relative to the main body portion to serve as the first abutting portion; the first pulling member 4 is of an integral structure.

[0064] In this embodiment, through the first stepped structure, the second stepped structure and the frustum-shaped structure, on the one hand, it is convenient to apply the pulling force, and on the other hand, it can avoid the contact between the first end of the first pulling member and the outer layer tube during the pulling process, thereby ensuring the smooth progress of the pulling process.

[0065] Embodiment 3

[0066] Preferably, this embodiment provides a double-layer tube expansion joint quality detection device. Compared with Embodiment 1, as Figure 3 shown, the following further design is carried out in this embodiment:

[0067] The double-layer tube expansion joint quality detection device further includes:

[0068] The first pulling bolt 6, the first pulling bolt 6 is connected to the second end of the first pulling member 4; wherein, the second end and the first end of the first pulling member 4 are opposite ends; the second pulling bolt 7, the second pulling bolt 7 is connected to the second end of the second pulling member 5; wherein, the second end and the first end of the second pulling member 5 are opposite ends;

[0069] The second end of the first pulling member is provided with a first connection structure for connecting the first pulling bolt; preferably, when the first pulling member is a rod-shaped structure, the first connection structure is a connection groove 8 provided on the second end of the first pulling member; the first pulling bolt 6 is threadedly connected to the connection groove 8; the second end of the second pulling member is provided with a second connection structure for connecting the second pulling bolt; preferably, when the second pulling member is a tubular structure, the second connection structure is a thread provided on the second end of the second pulling member; the second pulling bolt 7 is connected to the second pulling member 5 by a thread; the first pulling bolt is used to connect the tensile testing machine; the second pulling bolt is used to connect the tensile testing machine.

[0070] In this embodiment, pulling is carried out through a tensile testing machine to obtain the pulling force (tensile force) during the pulling process, and the expansion joint quality of the double-layer tube is characterized by the peak value of the force during the pulling process.

[0071] Embodiment 4

[0072] On the other hand, this embodiment provides a double-layer tube expansion joint quality detection method. The expansion joint quality detection method uses the double-layer tube expansion joint quality detection device of any one of the above, as Figure 3 shown, including the following steps:

[0073] Step 1): Sleeve the double-layer tube to be tested on the outer peripheral wall of the first pulling member 4, so that the first abutting portion on the first pulling member abuts against the end face of the inner layer tube 1 at the first end of the double-layer tube to be tested; sleeve the double-layer tube to be tested on the inner peripheral wall of the second pulling member, so that the second abutting portion on the second pulling member abuts against the end face of the outer layer tube 2 at the second end of the double-layer tube to be tested;

[0074] Step 2): Pull the first drawing part 4 away from the first end of the first drawing part 4, and pull the second drawing part 5 away from the first end of the second drawing part 5, so as to realize the drawing of the inner layer tube and the outer layer tube of the double-layer tube to be measured in opposite directions, and obtain the expansion joint quality detection result of the double-layer tube to be measured according to the magnitude of the drawing force during the drawing process;

[0075] Specifically, when drawing different double-layer tubes to be measured, at the same relative sliding displacement, the double-layer tube with a greater drawing force has better expansion joint quality.

[0076] Based on the method of this embodiment, by comparing the expansion joint quality of double-layer tubes made of different materials, double-layer tubes with higher expansion joint quality can be selected for bending forming, so as to avoid the relative sliding of the inner and outer layer tubes during bending and ensure the quality of the bent formed product.

[0077] Among them, the following method is used to process the expansion joint quality detection result of the double-layer tube to be measured: when both the inner and outer layer tubes are 304 stainless steel, when the maximum drawing force is 1500 N, the minimum bending radius at which the inner and outer layer tubes of the double-layer tube do not undergo relative sliding during bending forming obtained by finite element simulation is 84 mm. Therefore, when the expansion joint quality detection result of the double-layer tube is greater than 1500 N, the double-layer tube can be bent and formed with a bending radius exceeding 84 mm.

[0078] As Figure 1 shown, in this embodiment, the double-layer tube to be measured is prepared by the method of hydraulic expansion joint, including the following steps: First, select two single-layer tubes with different diameters, insert the small-diameter tube (inner layer tube) into the large-diameter tube (outer layer tube), and then place the inner and outer layer tubes into the (expansion joint) mold, as Figure 1 shown in a; then seal and liquid-expand the inner layer tube, so that the inner layer tube starts to plastically deform under the internal pressure until the inner layer tube contacts the outer layer tube, as Figure 1 shown in b; continue to pressurize, so that the outer layer tube expands together with the inner layer tube under the pressure of the inner layer tube until the double-layer tube fits the mold, as Figure 1 shown in c.

[0079] Experimental Example 1

[0080] This experimental example uses the expansion joint quality detection device and detection method of the double-layer tube described in the above embodiment to detect the expansion joint quality of the first double-layer tube to be measured and the second double-layer tube to be measured respectively, so as to select a double-layer tube more suitable for bending forming;

[0081] Among them, the first double-layer tube to be tested and the second double-layer tube to be tested are both prepared by the following method: Select two single-layer tubes with different diameters, insert the small-diameter tube (inner layer tube) into the large-diameter tube (outer layer tube), and then place the inner and outer layer tubes into a (expansion joint) mold; Then, seal and fluid-expand the inner layer tube, so that the inner layer tube starts to plastically deform under the internal pressure until the inner layer tube contacts the outer layer tube; Continue to apply pressure so that the outer layer tube expands together with the inner layer tube under the pressure of the inner layer tube until the double-layer tube fits the mold; Among them, the internal pressure is 100 MPa; The outer layer tubes of the first double-layer tube to be tested and the second double-layer tube to be tested have the same size, and the inner layer tubes of the first double-layer tube to be tested and the second double-layer tube to be tested have the same size; The outer layer tube and the inner layer tube of the first double-layer tube to be tested are both made of 304 steel; The outer layer tube of the second double-layer tube to be tested is made of 3004 aluminum, and the inner layer tube of the second double-layer tube to be tested is made of 304 steel;

[0082] The method for detecting the expansion joint quality of the first double-layer tube to be tested and the second double-layer tube to be tested specifically includes the following steps:

[0083] Step 1): Sleeve the double-layer tube to be tested on the outer peripheral wall of the first pulling member, so that the first abutting portion on the first pulling member abuts against the end face of the inner layer tube at the first end of the double-layer tube to be tested; Sleeve the double-layer tube to be tested on the inner peripheral wall of the second pulling member, so that the second abutting portion on the second pulling member abuts against the end face of the outer layer tube at the second end of the double-layer tube to be tested;

[0084] Step 2): Pull the first pulling member in the direction away from the first end of the first pulling member and pull the second pulling member in the direction away from the first end of the second pulling member to realize pulling the inner layer tube and the outer layer tube of the double-layer tube to be tested in opposite directions, and obtain the detection result of the expansion joint quality of the double-layer tube to be tested according to the magnitude of the pulling force during the pulling process;

[0085] Among them, a first pulling bolt is threadedly connected to the second end of the first pulling member, and a second pulling bolt is connected to the second end of the second pulling member. The first pulling bolt and the second pulling bolt are used to connect a tensile testing machine; The magnitude of the pulling force is displayed on the tensile testing machine.

[0086] According to this experimental example, the detection results of the expansion joint quality of the first double-layer tube to be tested and the second double-layer tube to be tested are respectively as Figure 4 shown in a and 4b. It can be seen that under the same internal pressure of hydraulic expansion joint, compared with the first double-layer tube to be tested, the expansion joint quality of the second double-layer tube to be tested is relatively higher, so it is more suitable for bending forming.

[0087] Experimental Example 2

[0088] In this experimental example, the expansion joint quality detection device and detection method of the double-layer pipe described in the above example are used to detect the expansion joint quality of the double-layer pipes to be tested under different internal pressures of hydraulic expansion, so as to select a more suitable double-layer pipe for bending forming;

[0089] Among them, the double-layer pipes to be tested are prepared by the following method: Select two single-layer pipes with different diameters, insert the small-diameter pipe (inner layer pipe) into the large-diameter pipe (outer layer pipe), and then place the inner and outer layer pipes into the (expansion joint) mold; Then seal and liquid-filled expand the inner layer pipe to make the inner layer pipe start plastic deformation under the internal pressure until the inner layer pipe contacts the outer layer pipe; Continue to apply pressure to make the outer layer pipe expand with the inner layer pipe under the pressure of the inner layer pipe until the double-layer pipe fits the mold;

[0090] Among them, the outer layer pipe of the double-layer pipe to be tested is made of 3003 aluminum alloy, and the inner layer pipe of the second double-layer pipe to be tested is made of 304 steel; The internal pressures of hydraulic expansion are respectively selected as 50 MPa, 100 MPa and 150 MPa;

[0091] The method for detecting the expansion joint quality of the double-layer pipes to be tested obtained under different internal pressures specifically includes the following steps:

[0092] Step 1): Set the double-layer pipe to be tested on the outer peripheral wall of the first pulling member, so that the first abutting portion on the first pulling member abuts against the end face of the inner layer pipe at the first end of the double-layer pipe to be tested; Set the double-layer pipe to be tested on the inner peripheral wall of the second pulling member, so that the second abutting portion on the second pulling member abuts against the end face of the outer layer pipe at the second end of the double-layer pipe to be tested;

[0093] Step 2): Pull the first pulling member in the direction away from the first end of the first pulling member and pull the second pulling member in the direction away from the first end of the second pulling member to realize pulling the inner layer pipe and the outer layer pipe of the double-layer pipe to be tested in opposite directions, and obtain the detection result of the expansion joint quality of the double-layer pipe to be tested according to the magnitude of the pulling force during the pulling process;

[0094] Among them, a first pulling bolt is threadedly connected to the second end of the first pulling member, a second pulling bolt is connected to the second end of the second pulling member, and the first pulling bolt and the second pulling bolt are used to connect a tensile testing machine; The magnitude of the pulling force is displayed on the tensile testing machine.

[0095] According to the detection results of the expansion joint quality of the double-layer pipes to be tested obtained under different internal pressures in this experimental example as Figure 5 shown, it can be seen that when the internal pressure of hydraulic expansion is 150 MPa, the expansion joint quality of the obtained double-layer pipe is higher than when the internal pressure of hydraulic expansion is 50 MPa or 100 MPa, that is, the expansion joint quality of the double-layer pipe increases with the increase of the internal pressure during hydraulic expansion (hydroforming).

[0096] The double-layer tubes obtained at the internal pressures of 50 MPa and 150 MPa in the hydraulic expansion joint of the experimental examples of this experiment were subjected to bending forming. As Figure 6 shown, during the bending forming process, for the double-layer tube obtained at an internal pressure of 50 MPa in the hydraulic expansion joint, relative sliding occurred between its inner and outer layers; while for the double-layer tube obtained at an internal pressure of 150 MPa in the hydraulic expansion joint, no relative sliding occurred between its inner and outer layers; therefore, the double-layer tube obtained at an internal pressure of 150 MPa in the hydraulic expansion joint is more suitable for bending forming, proving that the better the expansion joint quality, the higher the bending forming quality.

[0097] In the present invention, the expansion joint quality is characterized by comparing the peak values of the forces during the drawing process. Due to the different deformation amounts of the inner and outer layers during the expansion joint process, residual elastic strain exists between the double-layer tubes. The contact between the double-layer tubes is surface-to-surface contact. The tubes rebound due to deformation, and the different amounts of rebound result in a certain contact force between the inner and outer layers, so friction is generated, causing a frictional force to exist between the metal double-layer tubes after the expansion joint. According to f = μF, the device can reflect the magnitude of the frictional force by measuring the magnitude of the pulling force; through Figure 5 it can be seen that as the internal pressure of the double-layer tube shows a gradually increasing trend, the peak value of the pulling force required for the drawing operation also shows an increasingly large trend. This reflects that the frictional force also increases correspondingly under this increasing internal pressure. This positive correlation between the peak value of the pulling force and the frictional force and the internal pressure proves that the expansion joint quality of the double-layer tube will show a significant improvement as the internal pressure increases. It has extremely important guiding significance for the control and optimization of the expansion joint quality in related engineering applications.

[0098] It is easy for those skilled in the art to understand that, on the premise of no conflict, the advantageous technical features of the above various methods can be freely combined and superimposed.

[0099] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention. The above is only the preferred implementation manner of the present invention. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the technical principle of the present invention, several improvements and variations can be made, and these improvements and variations should also be regarded as within the protection scope of the present invention.

Claims

1. A double-layer pipe expansion quality detection device, characterized in that: The double-layer tube expansion quality detection device comprises: A first drawing member (4), the double-layer tube to be tested is used to be sleeved on the outer peripheral wall of the first drawing member (4); wherein the first end of the first drawing member (4) is provided with a first abutting portion, which is used to abut against the end surface of the inner tube (1) of the first end of the double-layer tube to be tested; A second drawing piece (5), the double-layer tube to be tested is used to be sleeved on the inner circumferential wall of the second drawing piece (5); a second abutting portion is provided at the first end of the second drawing piece (5) for abutting against the end face of the outer tube (2) at the second end of the double-layer tube to be tested; The first drawing member (4) and the second drawing member (5) are used to clamp the double-layer tube to be tested between the outer peripheral wall of the first drawing member (4) and the inner peripheral wall of the second drawing member (5), so as to realize drawing the inner layer tube and the outer layer tube of the double-layer tube to be tested in opposite directions and perform expansion quality inspection.

2. The double-layer pipe expansion quality detection device according to claim 1 is characterized in that: The first pulling member (4) is a rod-shaped structure.

3. The double-layer pipe expansion quality detection device according to claim 1 or 2, characterized in that: The first abutting portion is a first step structure provided at the first end of the first pulling member (4); wherein the step surface of the first step structure is used to abut against the end surface of the inner tube (1) at the first end of the double-layer tube to be tested; Preferably, the height h1 of the step surface of the first step structure is less than or equal to the thickness of the inner tube (1) in the double-layer tube to be tested; further preferably, the height h1 of the step surface of the first step structure is greater than or equal to half the thickness of the inner tube (1) in the double-layer tube to be tested; Preferably, the first step structure is arranged around the first end of the first drawing member (4); Preferably, the first abutting portion and the first pulling member (4) are an integrated structure.

4. The double-layer pipe expansion quality detection device according to claim 1 is characterized in that: The second pulling member (5) is a tubular structure.

5. The double-layer pipe expansion quality detection device according to claim 1 or 4, characterized in that: The second abutment portion is a second step structure provided at the second end of the second pulling member (5); wherein the step surface of the second step structure is used to abut against the end surface of the outer tube (2) at the second end of the double-layer tube to be tested; Preferably, the height h2 of the step surface of the second step structure is less than or equal to the thickness of the outer tube (2) in the double-layer tube to be tested; further preferably, the height h2 of the step surface of the second step structure is greater than or equal to half the thickness of the outer tube (2) in the double-layer tube to be tested; Preferably, the second step structure is arranged around the first end of the second pulling member (5); Preferably, the second abutting portion and the second pulling member (5) are an integral structure.

6. The double-layer pipe expansion quality detection device according to claim 1 is characterized in that: The first pulling member (4) comprises a first end, a second end and a main body portion located between the first end and the second end; The first end of the first drawing member is a truncated cone-shaped structure with one end being large and the other end being small; wherein the large end of the truncated cone-shaped structure is connected to the main body; and the small end of the truncated cone-shaped structure is the first end of the first drawing member; Preferably, the cross-sectional area of ​​the large end of the truncated cone-shaped structure is larger than the cross-sectional area of ​​the main body, so that the large end forms a circle of stepped surface relative to the main body to serve as the first abutting portion; Preferably, the first pulling member (4) is an integrated structure.

7. The double-layer pipe expansion quality detection device according to any one of claims 1 to 6, characterized in that: The double-layer pipe expansion quality detection device also includes: A first pull bolt (6), the first pull bolt (6) being connected to the second end of the first pull member (4); wherein the second end and the first end of the first pull member (4) are two opposite ends; A second pulling bolt (7), the second pulling bolt (7) being connected to the second end of the second pulling member (5); wherein the second end and the first end of the second pulling member (5) are two opposite ends; Preferably, the second end of the first pulling member is provided with a first connecting structure for connecting the first pulling bolt; preferably, when the first pulling member is a rod-shaped structure, the first connecting structure is a connecting groove (8) provided on the second end of the first pulling member; the first pulling bolt (6) is threadedly connected to the connecting groove (8); Preferably, the second end of the second pulling member is provided with a second connection structure for connecting the second pulling bolt; preferably, when the second pulling member is a tubular structure, the second connection structure is a thread provided on the second end of the second pulling member; the second pulling bolt (7) is connected to the second pulling member (5) via the thread; Preferably, the first pull-out bolt is used to connect to a tensile testing machine; and the second pull-out bolt is used to connect to a tensile testing machine.

8. A method for detecting the quality of expansion of a double-layer pipe, characterized in that: The expansion quality detection device for a double-layer pipe as described in any one of claims 1 to 7 is used to detect the expansion quality of the double-layer pipe to be detected.

9. The method for detecting the quality of expansion joint of a double-layer pipe according to claim 8, characterized in that: The method for detecting the expansion quality of the double-layer pipe comprises the following steps: Step 1): sleeve the double-layer tube to be tested on the outer peripheral wall of the first drawing member (4), so that the first abutting portion on the first drawing member abuts against the end face of the inner tube (1) of the first end of the double-layer tube to be tested; sleeve the double-layer tube to be tested on the inner peripheral wall of the second drawing member, so that the second abutting portion on the second drawing member abuts against the end face of the outer tube (2) of the second end of the double-layer tube to be tested; Step 2): Pull the first pulling member (4) in a direction away from the first end of the first pulling member (4), and pull the second pulling member (5) in a direction away from the first end of the second pulling member (5), so as to pull the inner tube and the outer tube of the double-layer tube to be tested in opposite directions, and obtain the expansion quality test result of the double-layer tube to be tested according to the magnitude of the pulling force during the pulling process.

10. The method for detecting the expansion quality of a double-layer pipe according to claim 8 or 9, characterized in that: The double-layer tube to be tested is prepared by the following method: The outer tube (2) is sleeved outside the inner tube (1), and the inner tube (1) is filled with liquid to expand the inner tube (1) so that the outer wall of the inner tube (1) fits with the inner wall of the outer tube (2).

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