Method and device for testing tensile property of spring pull rod

Abstract

The invention discloses a method and device for testing the tensile property of a spring pull rod, and the method comprises the steps: installing the tensile property testing device on an upper connector and a lower connector of a tension testing machine, and fixing the tensile property testing device through a pin; the upper and lower ends of the spring pull rod are connected in the tensile property testing device and are also fixed by pins; a program is set, the testing machine is stretched upwards, and the load value under the fixed elongation is detected; the special device for testing the tensile property of the spring pull rod comprises an upper connecting device and a lower connecting device, the friction force of the contact surface of the nut and the connector of the testing machine can be increased by screwing the tightening nut, so that the device and the connector of the testing machine can be tightly attached without loosening, and the accuracy of test data is ensured. The method is simple and easy to implement, the test device can reduce the influence on the measurement result, and the installation operation is simple.

Description

Technical Field

[0001] The present invention belongs to the technical field of material detection, testing and failure analysis, and relates to a method and device for testing the tensile performance of a spring pull rod, and specifically to a method and device for detecting the load of a spring pull rod under a certain elongation. Background Art

[0002] From a microscopic perspective, elastic deformation is the external force overcoming the interatomic force, causing the atomic spacing to change, while elastic recovery deformation is the interatomic force forcing the atoms to return to their original positions after the external force is removed. When metals are elastically deformed, there is a proportional linear relationship between stress and strain, which conforms to Hooke's law. The principle of the spring tie rod test is to analyze the force of the spring in the spring tie rod during the proportional elongation stage, that is, the load value under a certain elongation is determined according to the proportional linear relationship of Hooke's law. When measuring the load of the spring tie rod under a certain elongation, the displacement starting point of the testing machine is generally taken as the zero point to start recording, but the test machine structure gap and device gap will be introduced, affecting the accuracy of the test results. The commonly used spring tie rod tensile performance test device is a direct connection device designed according to the shape of the testing machine connector and the spring tie rod end. The device has high requirements on shape and size. If it cannot be fully fitted with the testing machine connector or is damaged, it will affect the accuracy of the load measurement under small elongation. Summary of the invention

[0003] The purpose of the present invention is to provide a method and device for testing the tensile performance of a spring pull rod, in order to solve the problem of load detection of the spring pull rod under a fixed elongation.

[0004] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0005] A method for testing the tensile properties of a spring pull rod, comprising:

[0006] Step 1: Place the upper connecting device into the upper connecting head of the tensile testing machine, and connect them by passing a pin through the base of the upper connecting device and the upper connecting head of the tensile testing machine;

[0007] Step 2: Place the lower connecting device into the lower connecting head of the tensile testing machine, and connect them by passing a pin through the base of the lower connecting device and the lower connecting head of the tensile testing machine;

[0008] Step three, process external threads on the outer wall of the upper connecting device, set a tightening nut, and assemble the tightening nut to the upper connecting device through threads; rotate the tightening nut with the aid of the auxiliary hole on the tightening nut, so that the tightening nut is in close contact with the end face of the upper joint of the testing machine, thereby fixing the upper connecting device with the upper connecting head of the testing machine without looseness; the lower connecting device is connected to the lower connecting head of the testing machine in the same way;

[0009] Step 4: Connect the single ear piece at the upper end of the spring pull rod to the fork ear piece of the upper connecting device with a pin;

[0010] Step 5: Set the initial force value, test speed and test end point of the tensile testing machine program;

[0011] Step 6: Set the load limit and travel limit of the tensile testing machine;

[0012] Step 7, before connecting the lower connecting device to the spring pull rod, reset the load of the testing machine to zero;

[0013] Step 8, adjusting the displacement of the testing machine crossbeam so that the double ear piece at the lower end of the spring pull rod matches the position of the single ear piece of the lower connecting device and then connects them with a pin;

[0014] Step nine, first move the beam of the testing machine upward, stretch the spring pull rod to the preset value and stop, then slowly move the beam of the testing machine downward until the force value is displayed as 0N and stop, at this time, reset the displacement of the testing machine;

[0015] Step 10, start the test and record the load value of the spring pull rod at a certain elongation measured in the test.

[0016] Furthermore, in step five, the initial force value does not exceed 5N.

[0017] Furthermore, in step five, the test speed is 10 to 30 mm / min.

[0018] Furthermore, the preset value in step nine is 5 to 15N.

[0019] A tensile performance testing device comprises an upper connecting device and a lower connecting device:

[0020] The upper connecting device comprises a cylindrical base and a fork ear piece; the bottom of the fork ear piece has a large arc chamfer; the connecting part between the base and the fork ear piece is cylindrical and provided with an external thread, which can be screwed into a tightening nut; both the cylindrical base and the fork ear piece have through holes, which are connected to the upper connector of the testing machine and the upper connector of the spring pull rod by pins and pins respectively;

[0021] The lower connecting device includes a cylindrical base and a single-ear ear piece; the bottom of the single-ear ear piece has a large arc chamfer; the connecting part between the base and the single-ear ear piece is cylindrical and has an external thread, which can be screwed in to tighten the nut; there are through holes on the cylindrical base and the single-ear ear piece, which can be connected to the lower connecting head of the testing machine and the lower connecting head of the spring pull rod with pins and pins respectively.

[0022] Furthermore, the tightening nut is in a circular ring shape, and has threads on its inner surface for being assembled to the upper connecting device and the lower connecting device.

[0023] Furthermore, auxiliary holes are evenly distributed on the outer side of the ring, each hole is 0.5° apart, and an auxiliary rod can be inserted to rotate the nut.

[0024] Furthermore, the inner surface thread of the tightening nut has at least three thread pitches.

[0025] Compared with the prior art, the present invention has the following technical features:

[0026] The method is simple and easy to implement, the test device can reduce the influence on the measurement result, and the installation and operation are simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of a spring pull rod tensile performance test device;

[0028] Figure 2 It is a schematic diagram of the structure of the connecting device on the spring pull rod tensile performance test device;

[0029] Figure 3 It is a schematic diagram of the structure of the lower connection device of the spring pull rod tensile performance test device;

[0030] Figure 4 is a schematic diagram of the tightening nut structure, and the tightening nuts in the upper and lower connecting devices have the same structure;

[0031] Among them: 1 is an upper connecting device, 2 is a lower connecting device, 3 is a tightening nut, 1-1 is the base of the upper connecting device, 1-2 and 2-2 are pins connecting the upper and lower connecting heads of the testing machine, 1-4 is a fork ear piece of the upper connecting device, 1-5 and 2-5 are pins connecting the spring pull rod, 2-1 is the base of the lower connecting device, 2-4 is a single ear piece of the lower connecting device, and 3-1 is an auxiliary hole on the tightening nut. DETAILED DESCRIPTION

[0032] In conjunction with the accompanying drawings, a method for testing the tensile properties of a spring pull rod is provided. The tensile properties testing device is installed on the upper and lower connecting heads of a tensile testing machine. A pin is passed through the hole on the base of the testing device and the fixed hole on the connecting head of the tensile testing machine at the same time. The upper and lower ends of the spring pull rod are connected to the tensile properties testing device. A positioning pin is passed through the hole at the end of the spring pull rod and the hole on the ear piece of the testing device at the same time. The program is set, the testing machine is stretched upward, and the load value under a certain elongation is detected. This method includes the following steps:

[0033] Step 1: Place the upper connecting device 1 into the upper connecting head of the tensile testing machine, and connect them by passing the pin 1-2 through the base 1-1 of the upper connecting device and the upper connecting head of the tensile testing machine;

[0034] Step 2: Place the lower connecting device 2 into the lower connecting head of the tensile testing machine, and connect them by passing the pin 2-2 through the base 2-1 of the lower connecting device and the lower connecting head of the tensile testing machine;

[0035] Step three, process external threads on the outer wall of the upper connecting device 1, set a tightening nut 3, and assemble the tightening nut 3 to the upper connecting device 1 through threads; rotate the tightening nut 3 with the help of the auxiliary hole 3-1 on the tightening nut 3, so that the tightening nut 3 is in close contact with the end face of the upper joint of the testing machine, thereby fixing the upper connecting device 1 with the upper connector of the testing machine without looseness; the lower connecting device 2 is connected to the lower connector of the testing machine in the same way;

[0036] Step 4: The single ear piece at the upper end of the spring pull rod is connected to the fork ear piece 1-4 of the upper connecting device by a pin 1-5;

[0037] Step 5: Set the initial force value, test speed and test end point of the tensile testing machine program; the initial force value does not exceed 5N, and the test speed is 10-30mm / min;

[0038] Step 6: Set the load limit and travel limit of the tensile testing machine;

[0039] Step 7, before connecting the lower connecting device 2 to the spring pull rod, clear the load of the testing machine;

[0040] Step 8, adjust the displacement of the testing machine beam so that the double ear piece at the lower end of the spring pull rod matches the single ear piece 2-4 of the lower connecting device and then connects them with pin 2-5;

[0041] Step nine, first move the beam of the testing machine upward, stretch the spring pull rod to the preset value and stop, then slowly move the beam of the testing machine downward until the force value is displayed as 0N and stop, at this time, the displacement of the testing machine is reset to zero; the preset value is 5~15N;

[0042] Step 10, start the test and record the load value of the spring pull rod at a certain elongation measured in the test.

[0043] In this solution, the tensile performance testing device includes an upper connecting device 1 and a lower connecting device 2:

[0044] The upper connecting device 1 includes a cylindrical base 1-1 and a fork ear piece 1-4; the bottom of the fork ear piece 1-4 has a large arc chamfer to increase the structural strength; the connecting part between the base 1-1 and the fork ear piece 1-4 is cylindrical and has an external thread, which can be screwed into a tightening nut 3; both the cylindrical base 1-1 and the fork ear piece 1-4 have through holes, which can be connected to the upper connector of the testing machine and the upper connector of the spring pull rod by pins 1-2 and 1-5 respectively.

[0045] The lower connecting device 2 includes a cylindrical base 2-1 and a single-ear ear piece 2-4; the bottom of the single-ear ear piece has a large arc chamfer to increase the structural strength; the connecting part between the base 2-1 and the single-ear ear piece 2-4 is cylindrical and has an external thread, which can be screwed into the tightening nut 3; both the cylindrical base 2-1 and the single-ear ear piece 2-4 have through holes, which can be connected to the lower connector of the testing machine and the lower connector of the spring pull rod by pins 2-2 and 2-5 respectively.

[0046] The tightening nut 4 is in the shape of a ring, and has threads on the inner surface for assembly to the upper connecting device 1 and the lower connecting device 2; three auxiliary holes 3-1 are evenly distributed on the outer side of the ring, and each hole is 120° apart, and an auxiliary rod can be inserted to rotate the nut; during the tightening process of the tightening nut 4, its end face contacts the surface of the upper and lower connecting heads of the testing machine to increase the friction, so that the upper and lower connecting devices 1 and 2 can fit tightly with the joints of the testing machine without looseness.

Claims

1. A method for testing the tensile properties of a spring pull rod, characterized in that: include: Step 1: Place the upper connecting device (1) into the upper connecting head of the tensile testing machine, and connect them by passing the pin (1-2) through the base (1-1) of the upper connecting device and the upper connecting head of the tensile testing machine; Step 2: Place the lower connecting device (2) into the lower connecting head of the tensile testing machine, and connect them by passing a pin (2-2) through the base (2-1) of the lower connecting device and the lower connecting head of the tensile testing machine; Step three, processing external threads on the outer wall of the upper connecting device (1), setting a tightening nut (3), and assembling the tightening nut (3) onto the upper connecting device (1) through threads; rotating the tightening nut (3) with the aid of the auxiliary hole (3-1) on the tightening nut (3) so that the tightening nut (3) is in close contact with the end face of the upper joint of the testing machine, thereby fixing the upper connecting device (1) with the upper connecting head of the testing machine without looseness; the lower connecting device (2) is connected to the lower connecting head of the testing machine by the same method; Step 4: the single ear piece at the upper end of the spring pull rod is connected to the fork ear piece (1-4) of the upper connecting device by a pin (1-5); Step 5: Set the initial force value, test speed and test end point of the tensile testing machine program; Step 6: Set the load limit and travel limit of the tensile testing machine; Step 7, before connecting the lower connecting device (2) to the spring pull rod, the load of the testing machine is reset to zero; Step eight, adjusting the displacement of the testing machine crossbeam so that the double ear piece at the lower end of the spring pull rod matches the single ear piece (2-4) of the lower connecting device and then connects them with a pin (2-5); Step nine, first move the beam of the testing machine upward, stretch the spring pull rod to the preset value and stop, then slowly move the beam of the testing machine downward until the force value displayed is 0N and stop, at this time, reset the displacement of the testing machine; Step 10, start the test and record the load value of the spring pull rod at a certain elongation measured in the test.

2. The method for testing the tensile properties of a spring pull rod according to claim 1, characterized in that: The initial force value in step 5 does not exceed 5N.

3. The method for testing the tensile properties of a spring pull rod according to claim 1, characterized in that: In step 5, the test speed is 10 to 30 mm / min.

4. The method for testing the tensile properties of a spring pull rod according to claim 1, characterized in that: The preset value in step nine is 5 to 15N.

5. A tensile properties testing device, characterized in that: It comprises an upper connecting device (1) and a lower connecting device (2): The upper connection device (1) comprises a cylindrical base (1-1) and a fork ear piece (1-4); the bottom of the fork ear piece (1-4) has a large arc chamfer; the connection part between the base (1-1) and the fork ear piece (1-4) is cylindrical and provided with an external thread, which can be screwed into a tightening nut (3); the cylindrical base (1-1) and the fork ear piece (1-4) are both provided with through holes, which are connected to the upper connection head of the testing machine and the upper connection head of the spring pull rod by a pin (1-2) and a pin (1-5) respectively; The lower connecting device (2) comprises a cylindrical base (2-1) and a single-ear ear piece (2-4); the bottom of the single-ear ear piece has a large arc chamfer; the connecting part between the base (2-1) and the single-ear ear piece (2-4) is cylindrical and provided with an external thread, which can be screwed into a tightening nut (3); both the cylindrical base (2-1) and the single-ear ear piece (2-4) have through holes, which can be connected to the lower connecting head of the testing machine and the lower connecting head of the spring pull rod by a pin (2-2) and a pin (2-5) respectively.

6. The tensile properties testing device according to claim 5, characterized in that: The tightening nut (4) is in the shape of a circular ring and has threads on its inner surface for being assembled on the upper connecting device (1) and the lower connecting device (2).

7. The tensile properties testing device according to claim 5, characterized in that: Three auxiliary holes (3-1) are evenly distributed on the outer side of the ring, each hole is 120 degrees apart, and an auxiliary rod can be inserted to rotate the nut.

8. The tensile properties testing device according to claim 5, characterized in that: The inner surface thread of the tightening nut (4) has at least three thread pitches.

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