JPH03572B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tensile test grip, particularly a tensile test grip used when performing a uniaxial load test of a test piece asymmetrical to the load line, such as a tensile test of anisotropic materials or a fracture toughness test. It's about the ingredients.

In a tensile test, in the case of a normal test piece, the direction of the test load and the direction of deformation coincide, and the test piece undergoes elongation deformation in response to the tensile test load, but in the case of an anisotropic material or one-sided notch, In the case of a test piece, the load direction and the deformation direction do not necessarily match, and shear deformation and bending deformation occur as well as elongation in response to a tensile load. Normally, a test piece gripper used in a tensile testing machine holds the test piece by pinching the end of the test piece with a pair of gripping pieces.
It has the advantage of simple structure and reliable holding, but when this type of grip is used for tensile testing of anisotropic materials, it eliminates the shearing and bending deformation that would occur due to the application of a tensile load. The gripping tool becomes restrained, and shear force and bending moment are applied to the test piece, making it impossible to perform an accurate uniaxial load tensile test even if a universal joint or the like is used. To solve this problem, the test specimen is held by pin support, but with this pin holding structure, a mounting hole is drilled at the end of the test specimen and a pin is inserted into the hole. , the test piece is attached to the testing machine via the pin, and the test piece is able to rotate using the space between the mounting hole and the pin, and even when a tensile load is applied, the test piece does not undergo shear deformation. Correct tensile tests can be performed without restricting bending or bending deformation. However, in the case of this pin support, the test load is concentrated on the mounting hole of the test piece, so it is easy to break from the mounting hole, and a large test load cannot be applied.

For this reason, in tensile tests of anisotropic materials, fracture toughness tests, etc., large tensile test loads are applied to tests that are mechanically asymmetrical with respect to the load axis, and on samples that are geometrically asymmetrical with respect to the load axis. There is a need for the development of a tensile test grip that can apply only a tensile load without restricting the shearing or bending deformation of the test piece.

This invention was made in view of the above circumstances, and is intended to be applied to samples that are mechanically asymmetrical with respect to the load axis or geometrically asymmetrical to the load axis in tensile tests or fracture toughness tests of anisotropic materials. To provide a tensile test gripping tool that can apply a large tensile test load to an asymmetrical sample, and that can apply only a tensile load without restricting shear deformation or bending deformation of the test piece. This is the purpose.

Corresponding to this purpose, the tensile test gripping tool of the present invention is provided with a gripping tool frame to be attached to a tensile testing apparatus, and which is positioned opposite to the gripping tool frame and is guided by an inclined surface formed on the said gripping tool frame at opposite intervals. and a pair of gripping pieces that are located opposite to each other and are supported by the sliding piece via a rotating shaft and can work together to clamp the test piece, and the sliding piece and the gripping piece are provided with It is characterized by a thrust bearing disposed between the two pieces.

Hereinafter, details of the present invention will be explained with reference to the drawings showing one embodiment.

In FIGS. 1, 2, and 3, reference numeral 1 indicates a gripping tool for tensile testing. Grip 1 is test piece 10
A pair is provided corresponding to both sides of the The gripping tool 1 includes a frame 2, sliding pieces 3a, 3b, and a pair of gripping pieces 4a, 4b.

The frame body 2 has a rigid structure and is attached to a testing machine (not shown) with attachment screws 22. A space 5 with one end open at the center of the frame 2
is provided. Opposite slopes 6a and 6b are formed on the side surfaces of this space 5 and gradually approach the open end 9.

Sliding pieces 3a and 3b are located within the space 5. The sliding pieces 3a, 3b are located opposite to each other, and guide surfaces 7a, 8b are formed on the back surfaces of each, and the guide surfaces 7a, 7b are in slidable contact with the slopes 6a, 6b of the frame 2. ing. Therefore, the sliding piece 3a,
3b is guided within the slopes 6a and 6b and is movable within the space 5, and as it approaches the open end 9 of the frame body 2, the facing distance becomes smaller and approaches.

Grip pieces 4a, 4b are supported on the sliding pieces 3a, 3b via rotating shafts 8a, 8b. The gripping pieces 4a, 4b are located opposite to each other, and the test piece 10 is held between the gripping surfaces 11a, 11b facing each other. The gripping surfaces 11a and 11b are formed with perpendicular serrations having a chevron-shaped cross section, and can hold the test piece in any direction of rotation. Thrust rolling bearings 12a, 12b are provided between the rotating shafts 8a, 8b and the sliding pieces 3a, 3b,
Therefore, the rotating shafts 8a, 8b are connected to the sliding pieces 3a, 3.
The gripping pieces 4a, 4b which are freely rotatable around the center of the rotating shafts 8a, 8b with respect to the rotating shafts 8a, 8b, and the sliding pieces 3a, 4b fixed to the tips of the rotating shafts 8a, 8b,
It is freely rotatable with respect to 3b. Grip surface 11
A positioning hole 13 is formed in the center of a, and a positioning pin 14 is provided protruding from a position on the gripping surface 11b opposite to the hole 13. This hole 13 and positioning pin 14 are connected to the test piece 1.
By engaging with the positioning hole 15 formed in 0,
This is for positioning the test piece 10 when attaching the test piece, and is not for applying a tensile test load to the test piece 10 from the testing machine. A hole 23 is formed in the center of the frame 2, and the flange portion 25 of the support cylinder 24 is inserted into the hole 23.
The frame body 2 is engaged with the frame body 2, and the support cylinder 24 is engaged with the frame body 2.
A relative rotational displacement is possible. This support cylinder 24 has an internal thread 26 and an external thread 2 of the mounting screw 22.
7, and a handle 28 is attached to the support cylinder 24 with a bolt 31. Therefore, the frame body 2 is linearly displaced with respect to the mounting screw 22 at the fixed position where the handle 28 is rotated, and the gripping piece 4
a and 4b approach or separate. However, spring 3
2 always acts in a direction to separate the frame body 2 and the sliding pieces 3a, 3b, so the opposing distances between the gripping pieces 4a, 4b tend to increase.

When carrying out a tensile test using the gripping device constructed in this manner, both ends of the test piece 10 are positioned between the gripping pieces 4a and 4b using the positioning holes 15. In this state, no tensile test load was applied to the test piece 10. Next, when the handle 28 is rotated and the frame 2 is pulled up, the sliding pieces 3a, 3b and the gripping pieces 4a, 4b, which are in fixed positions, are guided by the slopes 6a, 6b and approach each other by narrowing the distance between them, and finally cooperate. The end portion of the test piece 10 is held between the test pieces 10 and 10. In this state, next test machine (not shown)
When the frame body 2 is pulled up, a tensile test load is applied to the test piece 10 and the test piece 10 is deformed. Even if this deformation includes shear deformation or bending deformation other than elongation, the gripping pieces 4a and 4b are rotatable around the rotation axes 8a and 8b, so that the specimen 10 is not affected by shear deformation or bending. Accurate uniaxial load tensile tests can be performed without restricting deformation.

As described above, according to the present invention, a large tensile force can be applied to a sample that is mechanically asymmetrical with respect to the load axis or a sample that is geometrically asymmetrical with respect to the load axis in a tensile test or fracture toughness test of anisotropic materials. It is possible to obtain a tensile test grip that can apply a test load and can only apply a tensile load without restricting shear deformation or bending deformation of a test piece.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional front view showing a gripping tool according to an embodiment of the present invention, FIG. 2 is a sectional view taken at the negative part in FIG. 1, and FIG. 3 is a partial plan view showing the gripping tool. 1...Gripper, 2...Frame body, 3a, 3b...Sliding piece, 4a, 4b...Gripping piece, 6a, 6b...Slope, 7a, 7b...Guiding surface, 8a, 8b...Rotating shaft , 10... Test piece, 12a, 12b... Thrust rolling bearing.

Claims (1)

[Claims] 1. A gripper frame to be attached to a tensile test device, a pair of sliding pieces that are located opposite to each other and whose facing distance can be changed by being guided by slopes formed on the gripper frame, and A pair of gripping pieces supported by the sliding piece via a rotating shaft and capable of working together to clamp the test specimen are provided, and a thrust bearing is disposed between the sliding piece and the gripping piece. Features a tensile test grip.