Tension test device

Abstract

To provide a tension test device capable of suppressing a slip between chucks and a test piece.SOLUTION: A tension test device 10 for pulling a thin plate-like test piece T with incompressibility in at least one direction includes chucks 20 for pulling the test piece T by holding its one end side. The chucks 20 hold the one end side of the test piece T by magnetic force.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a tensile testing device that pulls a test specimen in at least one direction. [Background technology]

[0002] A tensile test is known in which a test piece is pulled in at least one direction to measure mechanical properties such as tensile strength, yield point, elongation, and reduction in area of ​​the test piece. A tensile test device that pulls the test piece in at least one direction when performing a tensile test is also known. For example, Patent Document 1 discloses a biaxial tensile test device that pulls a thin plate-shaped test piece in four directions.

[0003] The tensile testing device has a chuck that grips and pulls one end of a test piece. The chuck also has a pair of gripping parts that grip one end of the test piece. The pair of gripping parts are fixed by fixing means such as bolts and nuts in a state where they grip one end of the test piece. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-032219 A Summary of the Invention [Problem to be solved by the invention]

[0005] In a tensile testing device, when a test piece is made of a non-compressible material such as rubber, the thickness of the test piece decreases as the test piece is deformed by tension, and when the test piece is held by a fixing means such as a bolt and nut as described above, the holding force decreases and the test piece slips between the chuck and the test piece. In this case, the measurement accuracy of the tensile test is significantly reduced.

[0006] Therefore, an object of the present invention is to provide a tensile testing device that can suppress slippage between the chuck and the test piece. [Means for solving the problem]

[0007] The tensile testing apparatus of the present invention is a tensile testing apparatus that pulls a thin, plate-like, incompressible test piece in at least one direction, and is characterized in that it is equipped with a chuck that grips and pulls one end of the test piece, and the chuck grips one end of the test piece by magnetic force. Effect of the Invention

[0008] According to the tensile testing device of the present invention, slippage between the chuck and the test piece can be suppressed. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing a biaxial tensile testing device according to an embodiment. [Diagram 2] FIG. 2 is a schematic diagram illustrating a chuck according to an embodiment; [Diagram 3] 1 is a graph illustrating the effect of a tensile testing device. [Figure 4] FIG. 13 is a schematic diagram showing a chuck as another example of the embodiment. [Diagram 5] FIG. 13 is a schematic diagram showing a chuck as another example of the embodiment. [Figure 6] FIG. 2 is a schematic diagram showing a biaxial tensile testing device according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] An example of an embodiment of the present invention will be described in detail below. In the following description, specific shapes, materials, directions, values, etc. are merely examples for the purpose of easily understanding the present invention, and can be appropriately changed according to the application, purpose, specifications, etc.

[0011] [Biaxial tensile testing equipment] A biaxial tensile testing device 10 as one example of an embodiment will be described with reference to Figs. 1 to 3.

[0012] The biaxial tensile test apparatus 10 as a tensile test apparatus is an apparatus for performing a tensile test on a test piece T. In the tensile test, the test piece T is pulled in at least one direction to measure mechanical properties such as the tensile strength, yield point, elongation, and reduction in area of ​​the test piece T. The biaxial tensile test apparatus 10 can suppress slippage between the chuck 20 and the test piece T, as will be described in detail later.

[0013] The test piece T is an incompressible solid formed in a thin plate shape. Incompressibility refers to a property in which the density of a continuum does not change before and after deformation, and includes superelastic bodies such as rubber, and plastic bodies such as yielded metals. The thin plate shape is, for example, a rectangular shape with a thickness of 1 to 2 mm. The test piece T of this embodiment is, for example, tire rubber.

[0014] The biaxial tensile testing apparatus 10 is an apparatus that performs a tensile test on a test piece T by pulling the test piece T from four directions of two axes that are mutually perpendicular. However, the tensile testing apparatus of the present invention is not limited to the biaxial tensile testing apparatus 10. For example, the tensile testing apparatus may be a uniaxial tensile testing apparatus that performs a tensile test on the test piece T by pulling the test piece T from two mutually uniaxial directions.

[0015] In the following, for ease of understanding, the mutually orthogonal tensile directions of the test piece T will be described as the X direction and the Y direction, respectively, and the direction orthogonal to the X direction and the Y direction will be described as the up-down direction.

[0016] The biaxial tensile testing apparatus 10 includes chucks 20 provided on one side and the other side of the test piece T in the X and Y directions, a slide portion 11 to which the multiple chucks 20 are fixed, an actuator 12 that moves the slide portion 11 in the X or Y direction, and a control device 30 that controls the driving of the actuator 12.

[0017] The chucks 20 are provided on one side and the other side of the test piece T in the X direction and the Y direction, respectively, and grip one end side or the other end side of the test piece T in the X direction or the Y direction and pull it in the X direction or the Y direction. The chucks 20 allow the test piece T to be pulled to one side and the other side in the X direction and the Y direction at the same time. A plurality of chucks 20 (four in this embodiment) are provided on one side or the other side in the X direction or the Y direction. The chucks 20 are provided in an aligned manner on the slide portion 11. The chucks 20 will be described in detail later.

[0018] The slide parts 11 are provided on one side and the other side of the test piece T in the X direction and the Y direction, respectively, and are configured to be movable in the X direction or the Y direction. The slide parts 11 are configured to slide on a guide rail (not shown). Each slide part 11 is moved by an actuator 12.

[0019] The actuators 12 are provided on one side and the other side of the test piece T in the X direction and the Y direction, respectively, and move the respective slide parts 11 in the X direction or the Y direction. For example, an air cylinder is preferably used as the actuator 12. The actuator 12 has a cylinder 12A fixed to a base (not shown), and a rod 12B protruding from the cylinder 12A and fixed to the slide part 11.

[0020] The control device 30 controls the driving of the actuator 12, and switches ON / OFF the supply of electricity to an electromagnet 22 (described later) provided in the chuck 20. The control device 30 will be described in detail later.

[0021] [Chuck] As shown in FIG. 2, the chuck 20 has a gripping portion 21, an electromagnet 22 as a magnet, an iron piece 23 as a magnetic body, and a restricting portion 24, each of which will be described in detail later.

[0022] The gripping portion 21 grips one or the other end of the test piece T in the X-direction or Y-direction in order to pull the test piece T. The gripping portion 21 includes an upper gripping portion 21A and a lower gripping portion 21B. The upper gripping portion 21A and the lower gripping portion 21B are arranged side by side in the vertical direction and facing each other. The upper gripping portion 21A is arranged to be rotatable around a rotation axis P provided in the lower gripping portion 21B. The upper gripping portion 21A and the lower gripping portion 21B grip the test piece T by coming close to each other.

[0023] The electromagnet 22 is a magnet that generates a magnetic force temporarily when electricity is applied. The electromagnet 22 is provided on the upper part of the upper gripping part 21A. The electromagnet 22 is connected to a control device 30, which will be described later. The electromagnet 22 generates a magnetic force between itself and the iron piece 23 that faces the test piece T with the test piece T sandwiched therebetween. This allows the gripping part 21 to grip the test piece T by the magnetic force generated between the electromagnet 22 and the iron piece 23.

[0024] In this embodiment, the electromagnet 22 is used as the magnet, but the present invention is not limited to this. For example, a permanent magnet may be used as the magnet.

[0025] Here, when a non-compressible tire rubber such as the test piece T of this embodiment is pulled, the thickness of the test piece T decreases as the test piece T deforms due to pulling, and when the test piece T is held by a fixing means such as a bolt and nut, the holding force decreases and slippage occurs between the chuck and the test piece T.

[0026] However, as in the chuck 20 of this embodiment, by gripping the test piece T by the magnetic force generated between the electromagnet 22 and the iron piece 23 facing each other with the test piece T sandwiched therebetween, the thickness of the test piece T becomes smaller when the test piece T is deformed by pulling, but at the same time, the distance between the electromagnet 22 and the iron piece 23 becomes shorter, and the magnetic force attracting the electromagnet 22 and the iron piece 23 increases, and the gripping force of the gripping portion 21 also increases. This makes it possible to suppress slippage between the chuck 20 and the test piece T.

[0027] Furthermore, by providing the electromagnet 22 on the upper portion of the upper gripping portion 21A, the wiring connecting the control device 30 and the electromagnet 22 can be disposed above the chuck 20. This prevents the wiring from interfering with the movement of the chuck 20 and the sliding portion 11 when the chuck 20 and the sliding portion 11 move.

[0028] The iron piece 23 is provided below the lower gripping portion 21B. As described above, the iron piece 23 generates a magnetic force between itself and the electromagnet 22 that faces it with the test piece T in between. This allows the gripping portion 21 to grip the test piece T by the magnetic force generated between the electromagnet 22 and the iron piece 23. However, the magnetic body of the present invention is not limited to the iron piece 23. For example, nickel, cobalt, and alloys thereof (including iron), etc. may be used as the magnetic body.

[0029] The restricting portion 24 restricts the gap between the upper gripping portion 21A and the lower gripping portion 21B so that it does not exceed a predetermined distance. The restricting portion 24 includes a bolt and a nut. The restricting portion 24 can prevent the upper gripping portion 21A and the lower gripping portion 21B from opening too far apart, which would cause the test piece T to fall, when the electromagnet 22 is de-energized.

[0030] The chuck 20 can be realized by adding an electromagnet 22 and an iron piece 23 to a chuck that fixes a test piece T by a conventional fixing means such as a bolt and a nut. In this case, the fixing means of the conventional chuck becomes the restricting portion 24.

[0031] [Control device] 1 again, the control device 30 is connected to the actuator 12 and the electromagnet 22 (the connection lines between the control device 30 and the electromagnet 22 are omitted in FIG. 1). The control device 30 has a CPU (Central Processing Unit) which is an arithmetic processing unit, and storage units such as a RAM (Random Access Memory) and a ROM (Read Only Memory), and performs signal processing according to a program stored in advance in the ROM while utilizing the temporary storage function of the RAM.

[0032] The control device 30 has an actuator driving unit 31 that controls the driving of the actuator 12, an electromagnet ON / OFF switching unit 32 that switches the power supply to the electromagnet 22 between ON and OFF, and a current value setting unit 33 that sets the value of the current supplied to the electromagnet 22. The actuator driving unit 31, the electromagnet ON / OFF switching unit 32, and the current value setting unit 33 are realized by the CPU executing programs stored in the ROM or RAM.

[0033] The electromagnet ON / OFF switching unit 32 can turn off the electromagnet 22 so that no magnetic force is generated in the gripping unit 21. As a result, for example, when placing a test piece T in the gripping unit 21, the electromagnet 22 is turned off to turn on the test piece T in the gripping unit 21, so that the work efficiency can be improved by placing the test piece T in the gripping unit 21 in a state where the electromagnet 22 does not generate magnetic force.

[0034] According to the current value setting unit 33, the magnitude of the magnetic force generated between the electromagnet 22 and the iron piece 23 can be adjusted by adjusting the magnitude of the current value applied to the electromagnet 22. Therefore, the gripping force of the chuck 20 can be adjusted. This allows the gripping portion 21 to generate a magnetic force (gripping force) according to the thickness of the test piece T. As a result, tensile tests can be performed on test pieces T with different thicknesses.

[0035] [effect] In Fig. 3, the horizontal axis represents the tensile force and the vertical axis represents the gripping force, showing the relationship between the tensile force and the gripping force when a non-compressible test piece T is gripped by the chuck 20. Furthermore, when the gripping force is equal to or less than a predetermined value, slippage occurs between the chuck 20 and the test piece T. The dashed line in Fig. 3 shows the relationship between the tensile force and the gripping force of the chuck 20 gripped by a conventional fixing means using a bolt and a nut. Meanwhile, the solid line in Fig. 3 shows the relationship between the tensile force and the gripping force of the chuck 20 gripped by the magnetic force of the electromagnet 22 of this embodiment.

[0036] 3, when a non-compressible tire rubber such as the test piece T is pulled, the thickness of the test piece T decreases in the deformation of the test piece T due to tension, and the gripping force decreases as the tensile force increases. Here, the chuck 20 of the present embodiment can suppress the decrease in gripping force compared to conventional chucks, thereby suppressing slippage between the chuck 20 and the test piece T.

[0037] [Other embodiments] A chuck 40 as another example of the embodiment will be described with reference to Fig. 4. In the following description of the chuck 40, only the configuration different from the above-described chuck 20 will be described, and the description of the same configuration as the chuck 20 will be omitted.

[0038] The chuck 40 has a gripping portion 41, an electromagnet 42 as a magnet, and a restricting portion 44. The gripping portion 41 includes an upper gripping portion 41A and a lower gripping portion 41B. The electromagnet 42 is provided on the upper portion of the upper gripping portion 21A. The lower gripping portion 41B is formed of a magnetic material such as iron, nickel, cobalt, or an alloy thereof. The chuck 40 can suppress slippage between the chuck 40 and the test piece T. In addition, since the distance between the electromagnet 42 and the magnetic material is shorter than that of the chuck 20 described above, the gripping force can be further increased.

[0039] A chuck 50 as another example of the embodiment will be described with reference to Fig. 5. In the following description of the chuck 50, only the configuration different from the above-described chuck 20 will be described, and the description of the same configuration as the chuck 20 will be omitted.

[0040] The chuck 50 has a gripping portion 51, an electromagnet 52 as a magnet, and a restricting portion 54. The gripping portion 51 includes an upper gripping portion 51A and a lower gripping portion 51B. The electromagnet 52 is built into the upper gripping portion 51A. The lower gripping portion 41B is formed of a magnetic material such as iron, nickel, cobalt, or an alloy thereof. The chuck 50 can suppress slippage between the chuck 50 and the test piece T. In addition, the distance between the electromagnet 52 and the magnetic material is shorter than in the above-mentioned chuck 20 and chuck 40, so that the gripping force can be further increased.

[0041] A biaxial tensile test apparatus 110, which is another example of an embodiment, will be described with reference to Fig. 6. In the following, when describing the biaxial tensile test apparatus 110, only the configuration different from the above-mentioned biaxial tensile test apparatus 10 will be described, and the description of the same configuration as the biaxial tensile test apparatus 10 will be omitted.

[0042] The control device 30 of the biaxial tensile test apparatus 110 has an actuator driving unit 31 that controls the driving of the actuator 12, an electromagnet ON / OFF switching unit 32 that switches ON or OFF of the current to the electromagnet 22, a current value setting unit 33 that sets the current value to be passed to the electromagnet 22, and a current value increasing unit 34, the details of which will be described later. The actuator driving unit 31, the electromagnet ON / OFF switching unit 32, the current value setting unit 33, and the current value increasing unit 34 are realized by the CPU executing programs stored in the ROM or RAM.

[0043] The current value increasing unit 34 increases the magnitude of the current passed through the electromagnet 22 in response to an increase in the tensile force of the test piece T. Specifically, the current value increasing unit 34 increases the magnitude of the current passed through the electromagnet 22 in response to an increase in the driving force of the actuator 12. This causes the gripping force to decrease in response to an increase in the tensile force, but it is possible to increase the gripping force in response to the decrease in the gripping force.

[0044] It should be noted that the present invention is not limited to the above-described embodiment and its modified examples, and various modifications and improvements are possible within the scope of the matters described in the claims of this application. [Explanation of symbols]

[0045] 10, 110 Biaxial tensile test device (tensile test device), 11 Slide section, 12 Actuator, 12A Cylinder, 12B Rod, 20, 40, 50 Chuck, 21, 41, 51 Grip section, 21A, 41A, 51A Upper grip section, 21B, 41B, 51B Lower grip section, 22, 42 Electromagnet, 23 Iron piece (magnetic material), 24, 44, 54 Regulating section, 30 Control device, 31 Actuator drive section, 32 Electromagnet ON / OFF switching section, 33 Current value setting section, 34 Current value increasing section, T Test piece

Claims

1. A tensile testing device that pulls a thin, plate-like, incompressible test piece in at least one direction, A chuck is provided for gripping and pulling one end of the test piece, The chuck grips one end side of the test piece by magnetic force. Tensile testing equipment.

2. 2. The tensile testing apparatus of claim 1, A magnet is provided on one side of the chuck that holds the test piece, A magnetic body is provided on the other side of the chuck that holds the test piece. Tensile testing equipment.

3. 3. A tensile testing apparatus according to claim 2, The magnet is an electromagnet. Tensile testing equipment.

4. 4. The tensile testing apparatus of claim 3, increasing the magnetic force of the electromagnet in response to an increase in the pulling force of the chuck; Tensile testing equipment.

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