JPH06109609A - Chucking jig for biaxial tensile test of thin-plate material and biaxial tensile test method - Google Patents

Abstract

PURPOSE:To enable the part to be measured in the center of a test piece for biaxial tensile test to be uniformized in its stress and strain in performing a biaxial tensile test by using the test piece therefor made of thin plater material. CONSTITUTION:In a biaxial tensile test method, a chucking jig 3 for holding four sides of a biaxial tensile test piece 2 made of thin plate material is composed of a plurality of respectively divided chucking jigs 31, and such a test is performed by using the jig 3 in which the jig 31 can be moved in a plate- widthwise direction crossing diagonally the tensile direction of respective jigs 31.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gripping jig for a biaxial tensile test of a thin plate material, which is used for a biaxial tensile test of a thin plate material, and also uses the gripping jig for a biaxial tensile test. The present invention relates to a biaxial tensile test method for thin plate materials.

[0002]

2. Description of the Related Art Conventionally, in a biaxial tensile test method for a thin plate material, for example, a biaxial tensile test piece 51 having a cross shape as shown in FIG. 5 has been used.

This cross-shaped biaxial tensile test piece 51
Is provided with arm portions 53 each having a substantially triangular shape continuously on the four sides of the measured portion 52 at the center, and a plurality of mounting holes 54 for gripping jaw members (not shown) are provided in the vicinity of the end edges of each arm portion 53. It has the provided shape.

However, in such a biaxial tensile test piece 51 having a cross shape, a uniform stress distribution or a uniform stress distribution is exerted in the central measured portion 52 due to the influence of the rigidity of the arm portion 53 which is continuous in all directions. There is a problem that it is difficult to obtain the strain distribution.

Therefore, in order to solve such a problem, for example, a biaxial tensile test piece 61 having a cross shape as shown in FIG. 6 may be used to perform a biaxial tensile test.

[0006] This cross-shaped biaxial tensile test piece 61
Is provided with continuous strip-shaped arm portions 63 on each of the four sides of the measured portion 62 at the center, and each arm portion 63 has a shape in which a plurality of cuts 64 are formed in each pulling direction. .

In the biaxial tensile test piece 61 having a cross shape as described above, a plurality of cuts 64 are formed in the arm portion 63 in the respective pulling directions so that stress and strain in the central measured portion 62 can be reduced. It is designed to be uniform.

However, in such a biaxial tensile test piece 61, since the plurality of cuts 64 are formed in the arm portion 63, the strength of the arm portion 63 is relatively lowered, so that the center portion of the arm portion 63 is reduced. There is a problem that it is difficult to apply a sufficiently large stress to the measured portion 62 and generate a sufficiently large strain.

In order to solve such a problem, for example, a biaxial tension test piece 71 having a cross shape as shown in FIGS. 7 and 8 may be used to carry out the biaxial tension test.

This biaxial tensile test piece 71 having a cross shape
Is continuously provided with four arm portions 73 each having a strip shape on the four sides of the measured portion 72 in the center, and each arm portion 73 is formed with a plurality of slits 74 in each pulling direction, and The divided arm portions 73a divided by the formation are each provided with a reinforcing portion 75.

In the cross-shaped biaxial tensile test piece 71 as described above, in order to compensate for the decrease in strength due to the formation of the slit 74 in the arm portion 73, a reinforcing member molded separately is provided in the arm portion 73. The reinforcing portion 75 is fixed by adhesion, welding, or the like, the arm portion 73 is work-hardened by roll processing, or ribs are formed to form the reinforcing portion 7.
5 is provided to reinforce.

[0012]

However, in such a conventional biaxial tensile test piece 71, in order to obtain a uniform stress and strain distribution in the central measured portion 72. , A plurality of slits 7 in the arm 73
In order to compensate for the decrease in strength of the arm portion 73 due to the formation of the slit 74, the reinforcing member 75 is fixed and the reinforcing portion 75 is provided by work hardening or rib formation. There is a problem that it takes a lot of time and effort to manufacture the tensile test piece 71.

Although the arm portion 73 is strengthened by providing the arm portion 73 with the reinforcing portion 75, the arm portion 73 is strengthened.
Since the fracture may be easily caused in the root portion 76 of the joint due to stress concentration or heat effect due to welding, it is not possible to apply a sufficiently large stress to the measured portion 72 at the center. There is a problem that the strain obtained in the measuring unit 72 is not so improved.

Therefore, in the biaxial tensile test of the thin plate material, the stress and strain in the central portion to be measured can be made uniform, and it is possible to obtain a larger stress and strain. It has been an issue to be able to perform a material test up to the strain region.

[0015]

DISCLOSURE OF THE INVENTION The present invention has been made in view of such conventional problems, and in a biaxial tensile test of a thin plate material, stress and strain in a central measured portion are made uniform, and It is possible to obtain larger stress and strain, and it is possible to perform material tests on a thin plate material up to a larger plastic region or strain region. It is intended to provide a tensile test method.

[0016]

A gripping jig for a biaxial tensile test of a thin plate material according to the present invention is used for a biaxial tensile test of a thin plate material using a rectangular or cross-shaped biaxial tensile test piece. A gripping jig for thin plate material, wherein the gripping jig that holds the four sides of the biaxial tensile test piece is composed of a plurality of split gripping jigs, and the plurality of split gripping jigs are pulled by each split gripping jig. It is characterized in that it is configured to be movable in the plate width direction of the thin plate material orthogonal to the direction.

Further, the biaxial tensile test method for a thin plate material according to the present invention is carried out when a biaxial tensile test for a thin plate material is carried out using a rectangular or cross-shaped biaxial tensile test piece. A four-axis tensile test in which the four sides are held by a plurality of divided holding jigs and the divided holding jigs are movable in the plate width direction of the thin plate material orthogonal to the pulling direction by the divided holding jigs. It is characterized by having done.

In the embodiment of the gripping jig for the biaxial tensile test of the thin plate material according to the present invention, the width of the divided gripping jig becomes smaller toward the tip like a triangle or semicircle. It is desirable in some cases to have a tapered shape.

In order to make the split gripping jig movable in the plate width direction of the thin plate material orthogonal to the pulling direction by each split grip, a slider system, a roller system,
In some cases, it is desirable to have a structure that allows smooth movement by a ball system or the like.

Further, in the biaxial tensile test method for a thin plate material according to the present invention, a biaxial tensile test is conducted using a biaxial tensile test piece, and then a secondary test piece having a similar shape is obtained from the tensile test piece after the tensile test. By taking out the tensile test piece, the secondary tensile test piece is again subjected to the biaxial tensile test, and in some cases, the third, fourth ...
It is also possible to carry out a material test up to a larger plastic region or strain region.

[0021]

According to the present invention, the gripping jig for holding the four sides of the biaxial tensile test piece is composed of a plurality of split gripping jigs, and the plurality of split gripping jigs are arranged in a pulling direction by each split gripping jig. Using a gripping jig that is movable in the plate width direction of the thin plate material orthogonal to the above, when performing a biaxial tensile test, hold each of the four sides of the biaxial tensile test piece with a plurality of split gripping jigs and divide the A biaxial tensile test was performed by making the gripping jig movable in the plate width direction of the thin plate material orthogonal to the pulling direction by each divided gripping jig. The stress and strain in the measured portion at the center of the piece were made sufficiently uniform because each divided gripping jig was movable in the plate width direction of the thin plate material orthogonal to the pulling direction by each divided gripping jig. Thing Since a tensile test with a larger load than the conventional one is performed, it is possible to obtain a larger stress and strain, and two or more biaxial tensile tests can be performed on the same biaxial tensile test piece. By repeatedly performing the test, the material test up to the larger plastic region or strain region is performed.

[0022]

EXAMPLE FIG. 1 shows an example of a biaxial tensile test device used for carrying out the biaxial tensile test method for a thin plate material according to the present invention. Divided gripping jig 31 in which the four sides of the biaxial tensile test piece 2 of thin plate material are provided with the biaxial tensile test gripping jigs 3, respectively.
Each of the divided gripping jigs 31 is held by being gripped with, and each split gripping jig 31 is attached to the split gripping jig holding body 32.
3 is movably held in the plate width direction of the thin plate material orthogonal to the pulling direction by each split gripping jig 31, and the split gripping jig holding body 32 is provided with a driving hydraulic pressure via a pulling drive shaft 41. The driving hydraulic cylinder 42 is connected to the cylinder 42, and has a structure of being fixed to the device frame 43 having a strong rigidity.

Each driving hydraulic cylinder 42 feeds back the displacement value by means of a displacement sensor incorporated therein or by an extensometer attached to the biaxial tensile test piece 2, and mutually receives the mutual tensile drive. A biaxial tensile test is performed while the elongation of the shaft 41 is controlled so as to maintain a constant rate.

Biaxial tensile testing device 1 having such a structure
When performing a tensile test in a biaxial direction of the biaxial tensile test piece 2 having a rectangular shape by the above, the biaxial tensile test piece 2 is held by the divided gripping jigs 31 provided with a plurality of four sides, respectively, and the divided gripping is performed. In the plate width direction of the thin plate material which is orthogonal to the pulling direction of the jig 31 by each of the split gripping jigs 31 (that is, in FIG. 1, the upper and lower split gripping jigs 31 are in the horizontal direction, and the left and right split gripping jigs 31 are in the vertical direction). ) Is movable along the plate width direction shaft member 33, and a uniform stress and strain are applied to the measured portion at the center of the biaxial tensile test piece 2, while the drive hydraulic cylinder 42 is The biaxial tensile test is performed while pulling the respective products and applying tensile stress from the biaxial directions to the biaxial tensile test piece 2 via the tensile drive shaft 41.

Therefore, in the biaxial tensile test of such a thin plate material, the stress and strain in the measured portion at the center of the biaxial tensile test piece 2 are measured by the divided holding jigs 31 by the divided holding jigs 31. Since it is movable in the plate width direction of the thin plate material that is orthogonal to the direction, it becomes sufficiently uniform, and a biaxial tensile test with a larger load than the conventional one is possible, resulting in greater plasticity. Material testing up to the region or strain region is possible.

FIGS. 2 and 3 and 4 show an embodiment of a gripping jig for a biaxial tensile test of a thin plate material according to the present invention. As described with reference to FIG. As shown in FIG. 2, this gripping jig 3 for biaxial tensile test is provided with a split gripping jig 31 for gripping each of the four sides of the biaxial tensile test piece 2 of a rectangular thin plate material, and each split gripping jig. The tool 31 is movably held in the plate width direction shaft member 33 attached to the divided holding jig holder 32 in the plate width direction of the thin plate material orthogonal to the pulling direction by each of the divided holding jigs 31. The gripping jig holder 32 is fixed to the end of the pulling drive shaft 41.

As shown in more detail in FIGS. 3 and 4, the split grip jig 31 has a split grip jig jaw 31a having a plate width direction shaft member insertion hole 31b. The plate width direction shaft member 33 is inserted into the insertion hole 31b, and the plate width direction shaft member insertion hole 31 is formed.
A roller 36 is interposed between the pressure plate 35 provided on the rear wall 31c of the plate b and the plate width direction shaft member 33, whereby the split gripping jig 31 moves along the plate width direction shaft member 33. It is supposed to be able to move smoothly in the plate width direction.

Further, the tip portion (right end portion in FIGS. 3 and 4) of the split grip jig jaw portion 31a has a semicircular shape, and an opening portion 31d for fixing a tensile test piece is provided. The biaxial tensile test piece 2 is inserted into the opening 31d for fixing the test piece, and the gripping friction plates 37a and 37b are interposed above and below the test piece fixing bolt 3, respectively.
The biaxial tensile test piece 2 is fixed to the tip portion of the split grip jig 31 by tightening with 8a and 38b.

Therefore, when each pulling drive shaft 41 is driven in the pulling direction by the driving hydraulic cylinder (42), the pulling test piece 2 is pulled in the biaxial direction. When a displacement is generated in each direction, each divided gripping jig 31 is free to move in the direction orthogonal to each pulling direction and along the plate width direction shaft member 33 (that is, the plate width direction of the thin plate material). Because it moves
In the tensile test piece 2, a uniform stress and strain distribution can be obtained, and more accurate tensile stress / tensile stress can be measured.

In the biaxial tensile test method using the gripping jig 3 for the biaxial tensile test of the thin plate material according to the present invention, both a cross-shaped tensile test piece and a square-shaped tensile test piece can be used. Yes, it is not necessary to make a notch in the arm portion of the tensile test piece or to provide a reinforcing portion as in the conventional case, so that the production of the tensile test piece is remarkably reluctant, and the repetitive tensile test is reluctant. Moreover, it is possible to test the material in a large plastic region or strain region.

That is, in the biaxial tensile test, in the case of a cross-shaped tensile test piece, the material is used in the part of the arm that is continuous from the measured part in the center, and in the case of a rectangular tensile test piece, the material in the vicinity of the grip part. When the thin plate material is a steel plate or an aluminum plate material, the test can be performed only in a strain range of about 5 to 6%.

Therefore, in order to perform a material test in a larger plasticity range or strain range, a tensile test piece that has been fractured once or a tensile test piece that has been tested up to a predetermined strain amount immediately before fracture has a tensile test of a similar shape. The piece is taken out, and the tensile test piece is secondarily subjected to a biaxial tensile test.

In carrying out such a secondary biaxial tensile test, in the case of a cross-shaped tensile test piece, particularly a cross-shaped tensile test piece in which a notch is formed in the arm, due to its shape, With the same biaxial tensile tester, the maximum is two times, whereas when a rectangular biaxial tensile test piece is used in the present invention, it is cut out three times or more, usually 5 to 6 times. Can be repeated and a wide plastic range or strain range can be measured. Further, even when the cross-shaped tensile test piece is used, the length of the arm portion can be shortened, so that the number of repeated tests can be increased as compared with the conventional case.

[0034]

The gripping jig for the biaxial tensile test of the thin plate material according to the present invention is such that the gripping jig for holding the four sides of the biaxial tensile test piece is composed of a plurality of divided gripping jigs. The split gripping jig is configured to be movable in the plate width direction of the thin plate material orthogonal to the pulling direction by each split gripping jig, and the biaxial tensile test method of the thin plate material according to the present invention is a biaxial tensile test. A biaxial tensile test is performed by holding each of the four sides of the test piece by a plurality of divided gripping jigs and allowing the divided gripping jigs to move in the plate width direction of the thin plate material orthogonal to the pulling direction by each divided gripping jig. Because of the configuration, in the biaxial tensile test of the thin plate material, it is possible to make the stress and strain in the measured portion at the center of the biaxial tensile test piece sufficiently uniform, and it is also larger than the conventional one. To the load It is possible to perform a tensile test to obtain a larger stress and strain, and by performing two or more tensile tests repeatedly on the same tensile test piece, a greater plasticity can be obtained. It is possible to perform material tests up to the region or strain region, and it is not necessary to form a notch in the tensile test piece or to provide a reinforcing portion, so it is possible to manufacture the tensile test piece extremely easily. There are remarkably excellent effects such as being present.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a basic configuration of a biaxial tensile test device used in an example of a biaxial tensile test method for a thin plate material according to the present invention.

FIG. 2 is an explanatory diagram showing a basic configuration of a gripping jig for a biaxial tensile test of a thin plate material according to the present invention.

FIG. 3 is a cross-sectional explanatory view of a divided gripping jig in the gripping jig for biaxial tensile test shown in FIG.

FIG. 4 is an explanatory cross-sectional view taken along the line AA of FIG.

FIG. 5 is an explanatory diagram showing an example of a conventional biaxial tensile test piece.

FIG. 6 is an explanatory view showing another example of a conventional biaxial tensile test piece.

FIG. 7 is an explanatory view showing still another example of a conventional biaxial tensile test piece.

8 is a side view of the biaxial tensile test piece of FIG. 7. FIG.

[Explanation of symbols]

 1 Biaxial tensile test device for thin plate material 2 Biaxial tensile test piece for thin plate material 3 Biaxial tensile test gripping jig 31 Divided gripping jig 31a Divided gripping jig jaw 31b Plate width direction shaft member insertion hole 31d Tensile test One-sided fixing opening 32 Divided gripping jig holder 33 Plate width direction shaft member 41 Tension drive shaft 42 Driving hydraulic cylinder

Claims (2)

[Claims] 1. A gripping jig for a thin plate material, which is used in a biaxial tensile test of a thin plate material using a rectangular or cross-shaped biaxial tensile test piece, and which holds four sides of the biaxial tensile test piece. The jig is composed of a plurality of divided holding jigs, and the plurality of divided holding jigs are movable in a plate width direction of the thin plate material orthogonal to a pulling direction by each divided holding jig. A gripping jig for biaxial tensile testing of thin plate materials. 2. When performing a biaxial tensile test of a thin plate material using a rectangular or cross-shaped biaxial tensile test piece, each of the four sides of the biaxial tensile test piece is held by a plurality of divided gripping jigs. A biaxial tensile test method for a thin plate material, wherein the split gripping jig is movable in a plate width direction of the thin plate material orthogonal to a pulling direction by each of the split gripping jigs to perform a biaxial tensile test.