Test specimen gripping structure, test specimen gripping tool, and material testing method

Abstract

To provide a test piece grasping structure and a test piece grasping tool which allow a test piece to be grasped without imposing unnecessary load or moments on the test piece, and a method for testing a material.SOLUTION: The test piece grasping structure of the present invention is for grasping a test piece, and includes: a first grasping unit having a recessed part for containing the test piece; a second grasping unit fixed to the first grasping unit, the second grasping unit fixing the test piece; and a spring member arranged in a test piece container made of the recessed part of the first grasping unit and the second grasping unit, the spring member biasing the test piece.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a test piece gripping structure, a test piece gripping tool, and a material testing method. [Background technology]

[0002] When performing a load test using a test specimen, it is important to accurately apply a specified load and moment to the test specimen in order to improve test accuracy. A jig for a tensile tester that performs a tensile test without applying unnecessary forces such as tilting or rotation to the test specimen has been proposed. The jig includes a base body that fixes one end of the test specimen and a slider that fixes the other end of the test specimen and slides in one direction relative to the base body (see, for example, Patent Document 1). A clamping device that can clamp and fix a test specimen without a bending moment has also been proposed (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-35689 [Patent Document 2] Japanese Patent Application Publication No. 05-107164 Summary of the Invention [Problem to be solved by the invention]

[0004] 4A and 4B show a test specimen gripping device 100A conventionally used in load testing, with FIG. 4A being a side view and FIG. 4B being a front view. The test specimen gripping device 100A consists of two test specimen gripping structures 60A, each of which consists of a first gripping portion 10A, a second gripping portion 20A, and a bolt 40. In the test specimen gripping device 100A, a groove 22 conforming to the shape of the test specimen 50 is formed in the second gripping portion 20A, and the test specimen 50 is accommodated in this groove 22. This restrains the test specimen 50 in the load application direction, preventing the test specimen 50 from slipping. However, depending on the manufacturing precision, the flat surface of the gripping portion of the test specimen 50 may be twisted at both ends. When the first gripping portion 10A and the second gripping portion 20A are fixed with the bolt 40 while the flat surface of the first gripping portion 10A and the flat surface of the test specimen are aligned, an unnecessary torsional moment may be generated from both ends of the test specimen 50 to the center. Furthermore, in a test specimen gripping structure 60A that grips both ends of the test specimen 50, it is difficult to tighten the bolt 40 accurately and uniformly. This may result in unbalanced fastening between the test specimen gripping structures 60A at both ends as shown in FIG. 4A or within one test specimen gripping structure 60A as shown in FIG. 4B, which may generate a bending moment in the test specimen 50.

[0005] The present invention has been made in consideration of the above, and aims to provide a test specimen gripping structure, a test specimen gripping device, and a materials testing method that can grip a test specimen without applying unnecessary loads or moments to the test specimen. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the test piece gripping structure of the present invention is a test piece gripping structure for gripping a test piece, characterized in that it has a first gripping portion having a recess for accommodating the test piece, a second gripping portion fixed to the first gripping portion to fix the test piece, and a spring member arranged within a test piece accommodating portion consisting of the recess of the first gripping portion and the second gripping portion and for biasing the test piece.

[0007] Furthermore, in the test strip gripping structure according to the present invention, the height of the test strip accommodating section is greater than the thickness of the test strip.

[0008] In addition, the test strip gripping structure of the present invention is characterized in that, in the above invention, the second gripping portion is provided with an arc-shaped groove portion for accommodating the test strip, and the recess of the first gripping portion and the groove portion of the second gripping portion form a test strip accommodating portion.

[0009] In addition, the test piece gripping structure according to the present invention is characterized in that, in the above invention, the spring member is a leaf spring or a disc spring.

[0010] Moreover, in the test piece gripping structure according to the present invention, the spring member is fixed in a recess of the first gripping portion.

[0011] A test piece gripper according to the present invention is characterized by comprising two test piece gripping structures according to any one of the above.

[0012] Furthermore, a material testing method according to the present invention is characterized in that both ends of the test piece are fixed by any one of the test piece gripping structures described above. [Effects of the Invention]

[0013] According to the present invention, it is possible to grip a test piece without applying unnecessary loads and moments to the test piece. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a perspective view of a test piece gripper according to an embodiment of the present invention. [Figure 2] FIG. 2 is a partially enlarged view of the test piece gripper shown in FIG. [Figure 3A] FIG. 3A is a side view of the test strip gripper shown in FIG. [Figure 3B] 3B is a top view of the test strip gripper shown in FIG. 1. FIG. [Figure 3C] 3C is a front view of the test strip gripper shown in FIG. 1. FIG. [Figure 4A] FIG. 4A is a side view of a conventional test strip gripper. [Figure 4B] FIG. 4B is a front view of a conventional test strip gripper. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as "embodiments") will be described with reference to the accompanying drawings. Note that the drawings are schematic, and the relationship between the thickness and width of each part, the thickness ratio of each part, etc. may differ from the actual ones, and the drawings may also include parts with different dimensional relationships and ratios.

[0016] (Embodiment) Fig. 1 is a perspective view of a test strip gripper 100 according to an embodiment of the present invention, and Fig. 2 is a partially enlarged view of the test strip gripper 100. Also, Figs. 3A to 3C are a side view, a top view, and a front view of the test strip gripper 100.

[0017] The test strip gripping device 100 is composed of two test strip gripping structures 60. The test strip gripping structure 60 has a first gripping portion 10, a second gripping portion 20 that is fixed to the first gripping portion 10 and fixes an end of the test strip 50, and a spring member 30 that biases the test strip 50.

[0018] The first gripping portion 10 has a main body 11 and a recess 12 formed on the surface of the main body 11 facing the second gripping portion 20, which constitutes the test piece housing portion 70. The material constituting the main body 11 is appropriately selected from materials having appropriate rigidity, but SUS304 is preferred.

[0019] The second gripping portion 20 has a main body 21 and an arc-shaped groove 22 formed on the surface of the main body 21 facing the first gripping portion 10. The groove 22 accommodates the test specimen 50. The material of the main body 21 is selected from materials with appropriate rigidity, similar to that of the main body 11, but SUS304 is preferred. In this embodiment, the recess 12 of the first gripping portion 10 and the groove 22 of the second gripping portion 20 form a test specimen accommodation portion 70 (see FIG. 3C). The height L1 of the test specimen accommodation portion 70, i.e., the sum of the depth of the recess 12 and the depth of the groove 22, is greater than the thickness L2 of the test specimen 50 but less than the sum of the thickness L2 of the test specimen 50 and the length of the spring member 30 in the biasing direction when no load is applied. This allows the test specimen 50 to be fixed in place by the biasing force of the spring member 30. Note that Figure 3C shows the test piece gripping structure 60 after it has been fixed with the bolt 40, so the spring member 30 has contracted and the height L1 of the test piece storage section 70 is equal to the sum of the thickness L2 of the test piece 50 and the length of the spring member 30 in the biasing direction.

[0020] The spring member 30 is disposed within the test specimen storage section 70 and biases the test specimen 50. When a load is applied to secure the test specimen 50, the spring member 30 flexibly deforms to conform to the shape of the test specimen 50, preventing unnecessary load and moment loads from being applied to the test specimen 50 without excessively correcting the shape of the test specimen 50. Even if the flat portions of both ends of the test specimen 50 are twisted due to a decrease in manufacturing precision, the spring member 30 can deform to conform to the shape of the test specimen 50, preventing unnecessary load and moment loads from being applied to the test specimen 50. The spring member 30 is preferably joined to the recess 12 of the first gripping section 10 by welding or the like. A leaf spring or a disc spring is preferably used as the spring member 30, as it provides an appropriate biasing force.

[0021] The first gripping portion 10 and the second gripping portion 20 are fixed with the bolt 40 while the test specimen 50 is housed in the test specimen housing portion 70. The fixing method is not limited to the bolt 40. In this embodiment, even if a difference occurs in the fastening force of the bolt 30 within the test specimen holding structure 60, the spring member 30 deforms, thereby preventing unnecessary load and moment from being applied to the test specimen 50. Furthermore, since the test specimen 50 is housed in the recess 12 of the first gripping portion 10, the recess 12 acts as a stopper, preventing excessive tightening of the bolt 40.

[0022] After both ends of the test piece 60 are fixed by the test piece gripping device 100 of this embodiment, a material test can be performed. Examples of material tests include tensile tests, torsion tests, bending tests, compression tests, and fatigue tests. By using the test piece gripping device 100 of this embodiment, a material test can be performed while preventing unnecessary loads and moments from being applied to the test piece 50, thereby enabling the material test to be performed with high accuracy.

[0023] In the above embodiment, the test specimen gripping device was described as being used with a D-cut test specimen. However, the test specimen is not limited to D-cut specimens. It is also possible to prevent unnecessary loads and moments from being applied to flat test specimens. When using flat test specimens, it is not necessary to provide a groove in the second gripping portion. Furthermore, if no groove is provided in the second gripping portion 20, a recess may be provided in the second gripping portion, or a spring member may be fixed to the second gripping portion. Furthermore, in the above embodiment, the test specimen gripping device was configured with two test specimen gripping structures having the same configuration. However, by using at least one of the test specimen gripping structures of the present embodiment, unnecessary loads and moments from being applied to the test specimen can be prevented.

[0024] The present invention may include various embodiments not described here, and various design changes may be made within the scope of the technical idea specified by the claims.

[0025] As described above, the test piece gripping device according to the present invention can grip a test piece without applying unnecessary loads and moments to the test piece, thereby enabling material testing to be performed with high accuracy. [Explanation of symbols]

[0026] 10, 10A 1st grip part 11, 21 Main body 12 recess 20, 20A 2nd grip part 22 Groove 30 Spring member 40 volts 50 test specimens 60 Specimen gripping structure 70 Test piece storage section 100, 100A test specimen gripper

Claims

1. A test specimen gripping structure for gripping one end of a test specimen for material testing, with both ends fixed, comprising: a first gripping portion having a recess for accommodating a test strip; a second gripping portion fixed to the first gripping portion to fix the test piece; a spring member disposed in a test strip accommodating section formed by the recess of the first gripping section and the second gripping section, and biasing the test strip; A test piece gripping structure comprising:

2. 2. The test strip gripping structure according to claim 1, wherein the height of the test strip accommodating portion is greater than the thickness of the test strip.

3. The second gripping portion is provided with an arc-shaped groove portion for accommodating a test piece, 2. The test strip gripping structure according to claim 1, wherein the recess of the first gripping portion and the groove of the second gripping portion form a test strip accommodating portion.

4. 2. The test piece gripping structure according to claim 1, wherein the spring member is a plate spring or a disc spring.

5. 2. The test piece gripping structure according to claim 1, wherein the spring member is fixed in a recess of the first gripping portion.

6. A test strip gripping device comprising two test strip gripping structures according to any one of claims 1 to 5.

7. A material testing method characterized in that both ends of a test piece are fixed by the test piece gripping structure according to any one of claims 1 to 5.

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