A fixture for expansion test of alloy sheathed pipe of railway through-ground wire

Abstract

The present invention discloses a clamp for the expansion test of the alloy sheath pipe of the railway through-ground wire. The fixing seat is provided with an inner hole. The chuck is fixed in the inner hole of the fixing seat by using a conical surface. The pressure cap is connected and fastened to the fixing seat. The inner bottom wall of the pressure cap presses the chuck tightly. The pressure cap is provided with a hole. The chuck is provided with an axial through hole. The alloy sheath passes through the pressure cap and enters the axial through hole in the chuck. The inner top enters from the other end of the axial through hole. The inner top is provided with a tapered surface section, a guide shaft section, and a tail section in sequence. The tapered surface section enters the alloy sheath. The tapered surface presses the inner wall of the alloy sheath. The guide shaft section slides with the axial through hole of the chuck, and the tail section is outside the axial through hole. Beneficial effect: The alloy sheath pipe is clamped by the clamp, and the sheath pipe will not be deformed, bent or slid due to clamping. The axis of the sheath pipe and the axis of the conical top core are always kept in a straight line. The operation is simple and convenient, and the test is stable and good.

Description

Technical Field

[0001] The invention relates to the field of wire and cable detection equipment, in particular to a fixture for alloy sheath expansion test of through-ground wire products for high-speed railways. Background Art

[0002] High-speed railway environmentally friendly seamless metal through-ground wire is mainly laid on both sides of the railway. It is a cable for unified grounding of the entire railway signal system, ensuring reliable protection of personnel and equipment, and providing a discharge channel for overvoltages suffered by various types of equipment. The product works in harsh environments for a long time and can withstand severe vibration. The expansion test of the outer sheath alloy tube of the product must meet the requirements of GB / T242-2007 standard and TB / T 3479-2017 "Railway Through Ground Wire" 6.2.7 expansion test of the outer sheath to ensure the quality and service life of the product. At present, the sheath tube is clamped by a bench vise or other means, and then a 60° cone is used to extrude and expand to meet the test requirements. The disadvantage of this test method is that during the test, the sheath tube is clamped, extruded and expanded. If the clamping force is too large, the sheath tube will be flattened, deformed and bent. If the clamping force is too small, the sheath tube will slide during the extrusion and expansion process. If the clamping force is not well controlled, the test requirements cannot be met, and the quality requirements and mechanical properties of the sheath tube cannot be guaranteed. Summary of the invention

[0003] In order to solve the problem that the clamping force of a jacket pipe is difficult to control, the invention provides a clamp for carrying out an expansion test on a seamless and environment-friendly railway through-ground wire alloy jacket pipe.

[0004] The technical solution of the present invention is as follows: a fixture for the expansion test of the alloy sheath pipe of the railway through-ground wire, comprising a pressure cap, a fixing seat, a chuck, and an inner center. The fixing seat is provided with an inner hole, and the chuck is fixed in the inner hole of the fixing seat by a conical surface. The pressure cap and the fixing seat are connected and fastened together, and the inner bottom wall of the pressure cap presses the chuck tightly. The pressure cap is provided with a hole for the alloy sheath to pass through, and the chuck is provided with an axial through hole. The alloy sheath passes through the pressure cap and enters the axial through hole in the chuck, and the inner center enters from the other end of the axial through hole. The inner center is provided with a tapered surface section, a guide shaft section, and a tail section in sequence. The tapered surface section enters the alloy sheath, and the tapered surface presses the inner wall of the alloy sheath. The central axis of the guide shaft section coincides with the central axis of the axial through hole in the chuck, the guide shaft section slides with the axial through hole of the chuck, and the tail section is outside the axial through hole.

[0005] Since both the chuck and the inner center are tapered, it is not easy to disassemble after clamping the alloy sleeve. In order to facilitate disassembly, a disassembly sleeve and a push rod are further provided. The disassembly sleeve is arranged in the fixed seat and is connected by threads. The disassembly sleeve is provided with an outer cylindrical boss and a stepped inner hole. The end face contour of the end where the outer cylindrical boss is located is smaller than the circumference of the axial through hole of the fixed seat (the end face of the end where the outer cylindrical boss is located can enter the axial through hole and hit the end face of the chuck), the tapered surface section and the guide shaft section of the inner center can pass through the stepped inner hole, the tail section of the inner center is in the stepped inner hole of the disassembly sleeve, and the push rod is arranged in the disassembly sleeve to tighten the tail section of the inner center in a threaded connection manner.

[0006] The tail section of the inner top has a spherical surface, and pulling out the inner top makes it easier to hold and increase the force.

[0007] The inner wall of the pressure cap is provided with threads, and the connection mode with the fixing seat is threaded connection.

[0008] Preferably, the outer circle of the chuck is tapered, with three evenly distributed grooves, the tail of the groove is transitioned to a circular hole, and an annular groove is processed on the outer circumference where the circular hole is located, and the annular groove is located before the contact area between the inner center guide shaft section and the axial through hole.

[0009] The beneficial effects achieved by the present invention are as follows: the alloy sheath tube is clamped by the clamp, the sheath tube will not be deformed, bent or slipped due to clamping, and the axis of the sample (sheath tube) and the axis of the conical top core are always kept in a straight line until the expansion test is completed, the operation is simple and convenient, and the test is stable and good. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a structural diagram of the present invention;

[0011] Figure 2 It is the structure diagram of the chuck;

[0012] Figure 3 It is a diagram of the chuck structure in an axial view;

[0013] In the figure, 1. alloy sheath; 2. pressure cap; 3. fixing seat; 4. disassembly sleeve; 5. ejector rod; 6. inner center; 7. chuck. DETAILED DESCRIPTION

[0014] The present invention is further described below in conjunction with the accompanying drawings: Figure 1The outer surface of the chuck 7 has a conical surface, and the chuck 7 is fixed in the fixed seat 3 through the conical surface. The pressure cap 2 is connected to the fixed seat 3 by a threaded connection. The inner bottom wall of the pressure cap 2 presses the chuck 7, and the chuck 7 is deformed to clamp the alloy sheath 1. The tightening length of the pressure cap 2 and the chuck 7 can be controlled, so that the length of the chuck 7 entering the fixed seat 3 is also controlled, so the clamping force on the chuck 7 can be adjusted. At the same time, the contact area between the alloy sheath and the inner hole wall of the chuck is large, so a larger clamping force can be obtained, and the alloy sheath is not easy to deform. The inner top 6 is arranged in the chuck 7, and the small taper surface of the taper surface section of the inner top 6 is used to press the inner wall of the alloy sheath 1. The guide shaft section of the inner top 6 slides with the inner hole of the chuck 7, and the centering effect is good, so that the center axis of the alloy sheath coincides with the center axis of the inner hole of the chuck. The push rod 5 is arranged in the disassembly sleeve 4 to tighten the tail of the inner top in a threaded connection. The end face of the ejector pin is a plane, and the spherical surface at the tail of the inner tip 6 is in free contact with the ejector pin 5 and the plane of the disassembly sleeve 4 ( Figure 1 This is the state when the alloy sleeve is clamped. When the alloy sleeve is taken out and the inner top is removed, the inner hole end face of the disassembly sleeve 4 contacts the left side of the spherical surface under the action of the thread. The inner top guide shaft section will not produce radial resistance, and the small tapered surface of the inner top tapered surface section can evenly press against the inner wall of the alloy sleeve. The disassembly sleeve 4 is arranged in the fixed seat 3 and connected by threads. The outer cylindrical boss and the inner hole end face of the disassembly sleeve 4 contact the tail plane of the chuck 7 and the left side of the tail spherical surface of the inner top 6 respectively under the action of the thread, so that the chuck 7 can be easily ejected and the inner top 6 can be pulled out. Figure 2 , Figure 3 The chuck structure has a tapered outer circle of the chuck 7, with three grooves evenly distributed. The end of the groove is a circular hole to reduce stress concentration. An annular groove is machined on the outer circumference where the circular hole is located to reduce the wall thickness, and the taper is used to produce deformation at the thin wall. The annular groove is located before the contact area between the inner tip 6 guide shaft section and the axial through hole to avoid deformation of the axial through hole due to the taper in front of the annular groove, so that the inner tip 6 guide shaft cannot slide.

[0015] Usage process: the alloy sheath 1 first passes through the pressure cap 2 and then enters the chuck 7. The pressure cap 2 is screwed into the fixed seat 3, and the pressure cap 2 pushes against the chuck 7, forcing the chuck 7 to enter the inner hole of the fixed seat 3. The longer the pressure cap 2 is screwed in, the longer the length of the chuck 7 entering the inner hole of the fixed seat is. Due to the existence of the conical surface of the chuck 7, the alloy sheath 1 is subjected to a greater clamping force. The inner top 6 is made to enter the axial through hole of the chuck 7, and the part of the inner top 6 with a conical surface section smaller than the inner diameter of the alloy sheath 1 extends into the alloy sheath 1. The tail of the inner top 6 is forced, and the part of the inner top 6 with a conical surface section greater than or equal to the inner diameter of the alloy sheath 1 squeezes the alloy sheath 1 tightly. The inner top 6, the alloy sheath, and the inner wall of the axial through hole of the chuck 7 are in close contact, so the end of the alloy sheath 1 is limited. The disassembly sleeve 4 is screwed into the fixed seat 3, and the end face of the disassembly sleeve 4 does not contact the end face of the chuck 7. The push rod 5 is screwed into the disassembly sleeve 4 and touches the spherical surface of the tail of the inner top 6. When the alloy sheath is expanded, the pressing cap 2 is unscrewed from the fixing seat 3, and the disassembly sleeve 4 is further screwed in, so that the end face of the disassembly sleeve 4 contacts the end face of the chuck 7, and the chuck 7 is partially pushed out, and the contact between the chuck 7 and the inner hole of the fixing seat 3 is loosened, and the clamping force of the chuck 7 on the alloy sheath 1 is reduced. When separating the inner top 6, the disassembly sleeve 4 is continued to be screwed in, and the end face of the inner hole of the disassembly sleeve 4 contacts the left side of the spherical surface of the inner top 6, generating a backward pulling force on the inner top 6, and the tapered surface section of the inner top 6 is released from the close contact with the inner wall of the alloy sheath. At this time, hold the alloy sheath 1, pull it out of the chuck 7, and separate it from the pressing cap 2.

[0016] According to the expansion test procedure in GB / T242-2007 standard, "smoothly apply force to the conical top core to press it into the end of the sample for expansion until the required outer diameter is reached. During the expansion, the axis of the conical top core should be consistent with the axis of the sample." When using this fixture to conduct the expansion test of the seamless and environmentally friendly railway through-ground wire alloy sheath pipe, the alloy sheath will not slide under the fixation of the inner top core. The operation is simple and convenient, saving time and effort. It ensures that the axis of the sample is always consistent with the axis of the 60° conical top core during the test, meeting the requirements of GB / T242-2007 standard, and can not only conduct product expansion tests, but also meet the requirements of not damaging the sample during the expansion test. The test process is convenient, stable and reliable, ensuring the accuracy of the experimental results.

Claims

1. A fixture for the expansion test of the alloy sheath pipe of the railway through-ground wire, characterized by: It comprises a pressing cap (2), a fixing seat (3), a chuck (7), and an inner center (6), wherein the fixing seat (3) is provided with an inner hole, the chuck (7) is fixed in the inner hole of the fixing seat (3) by means of a conical surface, the pressing cap (2) and the fixing seat (3) are connected and fastened together, the inner bottom wall of the pressing cap (2) presses against the chuck (7), the pressing cap (2) is provided with a hole for the alloy sleeve (1) to pass through, an axial through hole is provided in the chuck (7), the alloy sleeve (1) passes through the pressing cap (2) and enters the axial through hole in the chuck (7), the inner center (6) enters from the other end of the axial through hole, the inner center (6) is provided with a tapered surface section, a guide shaft section, and a tail section in sequence, the tapered surface section enters the alloy sleeve (1), the tapered surface presses against the inner wall of the alloy sleeve (1), the guide shaft section slides with the axial through hole in the chuck (7), and the tail section is outside the axial through hole; A disassembly sleeve (4) and a push rod (5) are also provided. The disassembly sleeve (4) is arranged in the fixed seat (3) and connected by threads. The disassembly sleeve (4) is provided with an outer cylindrical boss and a stepped inner hole. The end surface profile of one end where the outer cylindrical boss is located is smaller than the circumference of the axial through hole of the fixed seat (3). The tapered surface section and the guide shaft section of the inner center (6) can pass through the stepped inner hole. The tail section of the inner center (6) is in the stepped inner hole of the disassembly sleeve (4). The push rod (5) is arranged in the disassembly sleeve (4) and is screwed to tighten the tail section of the inner center (6). The outer circle of the chuck (7) is tapered and has three evenly distributed grooves. The tail of the groove is transitioned to a circular hole. An annular groove is machined on the outer circumference where the circular hole is located. The annular groove is located before the contact area between the guide shaft section of the inner center (6) and the axial through hole.

2. A fixture for the expansion test of the alloy sheath pipe of the railway through-ground wire according to claim 1, characterized in that: The tail section of the inner top (6) has a spherical surface.

3. The fixture for the expansion test of the alloy sheath pipe of the railway through-ground wire according to claim 1 is characterized in that: The inner wall of the pressing cap (2) is provided with threads, and is connected to the fixing seat (3) by threaded connection.

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