Test piece gripping tool for tensile testing and tensile testing method

Abstract

To provide a specimen holding jig for a tensile test and a tensile test method with excellent economy, rationality and certainty, which can obtain highly reliable test results by performing a tensile test using a conventional tensile testing device such as a wedge method by applying a horizontal force without applying a compressive force to a specimen.SOLUTION: A tensile test specimen holding jig has a jig body 3 equipped with a chuck mounting part 1 to be held by one chuck part 9 of a tensile testing device for testing a specimen 8 held by a chuck part 9 and a specimen holding part 2 into which one end of the specimen 8 is inserted, and a pressing member 4 to prevent the slipping motion of the specimen 8 inserted into the specimen holding part 2. The pressing member 4 is a pressing bolt 4 that comes into contact with the specimen 8 in a direction approximately perpendicular to the specimen to exert a pressing force, and a projection 41a or the like is formed at the tip of the pressing bolt to cause deformation on the surface of the specimen 8 while exerting a pressing force on the specimen 8.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to the technical field of a test piece gripping jig for a tensile test used in a tensile testing device that measures the mechanical properties of a material by gripping a test piece in a chuck portion for testing, and a tensile testing method using the same jig. [Background technology]

[0002] As an example of a tensile testing device that measures the mechanical properties of a material by holding a test piece in a chuck and conducting a test, there is a tensile testing device shown as a conventional technique in FIG. 2 of Patent Document 1. This tensile testing device first chucks one side (upper side) of the test piece, and then when chucking the other side (lower side), a wedge method is adopted in which the chuck part (grip 2 in the document 1) moves upward to chuck the test piece, creating a wedge effect. However, when the test piece is chucked (gripped) using the wedge method, a compressive force acts on the test piece when one side of the test piece is chucked and then the other side is chucked, which raises the problem of doubts about the reliability of the test results.

[0003] Therefore, the device according to the above-mentioned Patent Document 1 is configured to interpose a jig (test piece gripper) between the test piece and the tensile testing device as shown in Figures 3 and 4. This configuration allows the test piece to be tested without the compressive force from the chuck part acting on the test piece as in the above-mentioned prior art, thereby solving the above-mentioned problem. However, the technology according to Patent Document 1 requires that grooves (1a) be machined on both sides of the test piece (1A), as can be seen in Figure 4 of Patent Document 1. In the case of a thin plate-shaped test piece, however, a new problem arises in that the test piece is not thick enough to provide grooves, making this difficult to implement.

[0004] In recent years, there has been a device known as a precision universal testing machine that is equipped with a chuck that can grip a test piece in parallel using air or hydraulic pressure (see, for example, Patent Document 2). This device allows a tensile test to be performed without applying a compressive force to the test piece, so that highly reliable test results can be obtained even for thin plate-like test pieces. However, there are problems in that the cost of the device itself is high and new installation space is required, making it uneconomical and unreasonable. Therefore, the reality is that a technology that can be implemented economically using a conventional tensile testing device such as that disclosed in Patent Document 1 (for example, the wedge-type tensile testing device) is still desired. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Utility Model Application Publication No. 60-129654 [Patent Document 2] Utility Model Registration No. 3111445 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been devised in view of the problems in the background art described above, and an object of the present invention is to provide a test piece gripping jig for a tensile test and a tensile test method which are excellent in economy, rationality and reliability, and which can obtain highly reliable test results by performing a tensile test by applying a horizontal force to the test piece without applying a compressive force to the test piece, using a conventional tensile tester such as the wedge type, without processing the test piece. [Means for solving the problem]

[0007] As a means for solving the above problems, the test piece gripping jig for tensile testing according to the invention described in claim 1 comprises a jig body including a chuck attachment portion that is gripped by one of the chuck portions of a tensile testing device that grips a test piece in the chuck portion for testing, and a test piece gripping portion into which one end of the test piece is inserted, and a pressing member that prevents the test piece inserted into the test piece gripping portion from slipping. 、 The test piece is not subjected to any processing such as groove processing or bending processing. The pressing member is a pressing bolt that contacts the unprocessed test piece in a substantially perpendicular direction to apply a pressing force, and the pressing bolt has a protrusion at its tip that applies a pressing force to the test piece and causes deformation on the surface of the test piece. It is characterized by:

[0010] Claim 2 The invention described in claim 1 The test piece gripping jig for a tensile test described above is characterized in that it has a positioning member provided between the test piece gripping portion and the test piece for adjusting the position of the test piece.

[0011] Claim 3 The tensile test method according to the invention described in claim 1 or 2 a test piece gripping jig for a tensile test according to claim 1, further comprising: a test piece gripping jig for a tensile test using the test piece gripping jig described in claim 1, the test piece being gripped at the other end of the test piece by the other chuck portion of the tensile test device; and a test piece gripping jig body for a tensile test being gripped at one chuck portion of the tensile test device by utilizing the chuck attachment portion while one end of the test piece is inserted into the test piece gripping portion. Thereafter, the pressing member is passed substantially horizontally through a hole formed in the test piece gripping portion to fix the test piece, and then a tensile test is performed. Effect of the Invention

[0012] The test piece gripping jig for tensile testing and the tensile testing method using the same according to the present invention have the following advantages. A tensile test can be performed by horizontally screwing a pressing member (pressing bolt) into the jig body having a chuck mounting portion and a test piece gripping portion. Therefore, even with conventional tensile testing equipment such as the wedge method, a tensile test can be performed by applying a horizontal force to the test piece without applying a compressive force to the test piece, thereby obtaining highly reliable test results. In addition, the test piece gripping jig for tensile testing according to the present invention has a very simple structure and can be used simply by inserting one of the chuck portions of a tensile testing device, making it very economical and easy to use. Furthermore, the fixing effect of the specially processed protrusions (conical protrusions and / or annular protrusions, etc.) on the tips of the compression bolts reliably prevents the test pieces from shifting, thereby making it possible to obtain highly reliable test results. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a front view showing a state in which a tensile test is performed using a test piece gripping jig for a tensile test according to the present invention. [Diagram 2] FIG. 2 is a right side view showing a main part of FIG. 1. [Diagram 3] FIG. 1A is a front view showing a test piece gripping jig for a tensile test according to the present invention, FIG. [Figure 4] 3A and B is a plan view of A. FIG. [Diagram 5] FIGS. 1A and 1B are front views showing a pressing bolt used in a test piece gripping jig for a tensile test according to the present invention, FIGS. 1C and 1D are right side views of A and B, respectively, E is an enlarged view of part E (the tip of the pressing bolt) of A and B, and F is a left side view of E. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Next, an embodiment of a test piece gripping jig for a tensile test and a tensile test method using the same according to the present invention will be described with reference to the drawings.

[0015] The test piece gripping jig for the tensile test is, as shown in Figs. No grooves, bends, or other processing has been done. The jig is characterized by having a chuck mounting portion 1 that is gripped by one chuck portion 9 (the lower one in this embodiment) of a tensile testing device 10, which grips a test piece 8 in the chuck portion 9 for testing, a jig body 3 that has a test piece gripping portion 2 into which one end of the test piece 8 is inserted, and a pressing member 4 that prevents the test piece 8 inserted into the test piece gripping portion 2 from slipping.

[0016] The test piece gripping jig for tensile testing according to the present invention has a simple configuration comprising the jig body 3 and the pressing member 4, and can obtain highly reliable test results by performing a tensile test by applying a horizontal force to the test piece 8 without applying a compressive force thereto. In this embodiment (illustrated example), a positioning member 5 and a reinforcing member 6 are further provided on the side of the jig body 3, but these members 5 and 6 are so-called sub-members for performing tests more smoothly. It should be noted that even without the members 5 and 6, a tensile test can be performed by applying a horizontal force to the test piece 8 without applying a compressive force, thereby obtaining highly reliable test results. Each component will be described below.

[0017] As an example, the jig body 3 is composed of a plate-shaped chuck mounting portion 1 that is gripped by one (usually the lower) chuck portion 9 of a conventional wedge-type tensile testing device 10, and a test piece gripping portion 2 that rises and sandwiches the upper portion (upper end portion) of the chuck mounting portion 1 and is integrated with the chuck mounting portion 1 by welding and joining means. In this embodiment, the chuck attachment portion 1 is made of metal and is formed into a rectangular thin plate with, for example, vertical sides (long sides) of about 130 mm, horizontal sides (short sides) of about 60 mm, and a plate thickness of about 6 mm. The portion that is gripped by the chuck portion 9 of the tensile testing device 10 has a roughening process 1a (see FIG. 4A) applied to the surface. The form (size, shape) of the chuck attachment portion 1 is not limited to this, and can be appropriately changed in design. However, the plate thickness is set to be equal to or greater than the thickness of the test piece 8 (about 1 mm in this embodiment). In this embodiment, the chuck attachment portion 1 and the test piece gripping portion 2 are integrated by a welding means, but the present invention is not limited to this, and they can be implemented by a bolting means, or a combination of a welding means and a bolting means. Incidentally, the symbol w in the figure indicates a weld bead.

[0018] In this embodiment, the test piece gripping portion 2 is composed of a pair of metallic clamping members 21, 22, and each of the clamping members 21, 22 is, for example, of approximately the same shape and size, and is formed into a rectangular parallelepiped shape with a vertical side (long side) of approximately 72 mm, a horizontal side (short side) of approximately 50 mm, and a plate thickness of approximately 25 mm.One of the clamping members 21 has two bolt holes (female threads) for screwing in the pressing member 4 drilled in a balanced manner on the left and right sides in the horizontal direction (specifically, in a direction approximately perpendicular to the test piece 8 to be received in the test piece gripping portion 2). The shape of the test piece gripping portion 2 is not limited to this, and can be appropriately modified in design. However, it is required that the pressing member 4 can be screwed in horizontally in a stable position, and that the test piece 8 can be securely prevented from slipping while a tensile test can be performed.

[0019] In this embodiment, the pressing member 4 is a pressing bolt 4 that contacts the test piece 8 in a substantially perpendicular direction (horizontal direction) and applies a pressing force to the test piece 8. As shown in Figs. 5E and 5F, the pressing bolts 4 (41, 42) have protrusions 41a (42a), 41b (42b) at their tips that apply a pressing force to the test piece 8 and cause deformation in the surface of the test piece 8. Specifically, the protrusions are conical protrusions 41a, 42a and annular protrusions (annular ridges) 41b, 42b, and the tips of the pressing bolts 41, 42 are induction hardened and specially processed to ensure that they bite into the steel material (test piece 8). Depending on the hardness of the test piece 8, it may be possible to form only one of the conical protrusions 41a, 42a and the annular protrusions 41b, 42b. In addition, the pressing bolts 4 according to this embodiment are implemented by using two pressing bolts 4 on the left and right in a balanced manner to reliably prevent the slippage of the test piece 8 inserted into the test piece gripping portion 2, but are not limited to this. The number, arrangement, and size of the bolts can be appropriately designed and changed depending on the size (particularly the width) and hardness of the test piece 8, and one bolt may be used, or three or more bolts may be required. Incidentally, in this embodiment, two pressing bolts 41 and 42 of M16 are used for the width of the test piece 8 at the portion inserted into the test piece gripping portion 2, which is about 50 mm. When using multiple pressing bolts 4, in order to perform a good screwing operation, as shown in the example, a pressing bolt 41 with a square head ground so as not to interfere with the head of the adjacent pressing bolt 42 or a hexagonal socket set screw may be appropriately devised.

[0020] The test piece gripping portion 2 also has a reinforcing member 6 arranged so as to straddle both the left and right ends of the pair of clamping members 21, 22 facing each other, and is integrated by a welding joint means. The reinforcing member 6 is provided to firmly restrain the clamping members 21, 22 so as to prevent the gap between them from expanding due to the pressing action of the pressing member (pressing bolt) 4. Incidentally, in this embodiment, the reinforcing member 6 is made of metal and is implemented as a rectangular plate having a vertical side (short side) of about 40 mm, a horizontal side (long side) of about 50 mm, and a plate thickness of about 9 mm, for example. Note that the form (size, shape) of the reinforcing member 6 is not limited to this, and can be appropriately changed in design. In this embodiment, the test piece gripping portion 2 (a pair of clamping members 21, 22) and the reinforcing member 6 are integrated by a welding joint means, but this is not limited thereto, and they can be implemented by a bolt joint means, or by using a combination of a welding joint means and a bolt joint means.

[0021] Furthermore, in this embodiment, a positioning member 5 is detachably provided inside the test piece gripping portion 2 (between the pair of clamping members 21 and 22 facing each other). This positioning member 5 is The positioning member 5 is provided between the test piece gripping portion 2 and the test piece 8, and serves to adjust the alignment of the cores (axial cores) of the tensile testing device 10 and the test piece 8. The positioning member 5 according to this embodiment is formed by bending a metal plate having a thickness of about 2 mm into an L-shape, and is provided so as to be attached to the back side of the test piece 8 in a configuration in which it is hooked onto the test piece gripping portion 2. The positioning member 5 is provided to align the core of the test piece 8, which is gripped and hung by one chuck portion 9 (the upper side in this embodiment) of the tensile testing device 10, with the core of the tensile testing device 10, and the thickness of the positioning member 5 itself serves as a spacer. However, the positioning member 5 is unnecessary when the center (axial center) of the tensile testing device 10 and the test piece 8 are aligned, for example, when the interval between the clamping members 21, 22 (the plate thickness of the chuck mounting portion 1) is approximately equal to the plate thickness of the test piece 8. However, it is more economical and rational to prepare several positioning members 5 with a simple structure than to prepare several jig bodies 3 with different intervals according to the plate thickness of the test piece 8. Although not shown in the drawings, the tensile test can be performed by temporarily fixing the positioning member 5 with a bolt to the upper surface or the like of the clamping member 22. In the illustrated example, the positioning member 5 is formed into an inverted L-shape that is easy to hook onto the test piece gripping portion 2, but it can also be formed into a simple flat plate shape.

[0022] Therefore, the tensile testing method using the tensile test specimen gripping jig of the above configuration first involves gripping the other end (upper part) of the test specimen 8 with the other chuck portion 9 (the upper part in this embodiment) of the tensile testing device 10, and supporting the test specimen 8 in a vertical direction by suspending it. Next, the jig body 3, on which the positioning member 5 has been set in advance, is gripped by one of the chuck portions 9 (the lower one in this embodiment) of the tensile testing device 10 using its chuck mounting portion 1, and one end (lower portion) of the test piece 8 is inserted into the test piece gripping portion 2. Thereafter, the pressing bolts 41, 42 are screwed substantially horizontally into the bolt holes (female threads) formed in the clamping member 21 of the test piece gripping portion 2. The pressing bolts 41, 42 contact the test piece 8 in a substantially perpendicular direction to apply a pressing force, while the protrusions (conical protrusions 41a, 42a and annular protrusions 41b, 42b) provided at the tips of the pressing bolts 41, 42 cause deformation in the surface of the test piece 8, thereby firmly fixing the test piece 8. The test piece 8 is firmly fixed to the jig body 3 while maintaining a vertical position due to the attachment effect of the positioning member 5 and the fixing effect of the protrusions of the pressing bolts 41, 42. Therefore, a tensile test performed thereafter can obtain highly reliable test results. It should be noted that the above-mentioned procedure for the tensile test is merely one example.

[0023] As described above, according to the test piece gripping jig for tensile tests and the tensile testing method using the same jig of the present invention, a tensile test can be performed by horizontally screwing the pressing member 4 (pressing bolts 41, 42) into the jig body 3 having the chuck mounting portion 1 and the test piece gripping portion 2. Therefore, even with a conventional tensile testing device 10 such as a wedge type, a tensile test can be performed by applying a horizontal force to the test piece 8 without applying a compressive force to the test piece 8, thereby obtaining highly reliable test results. Furthermore, the test piece gripping jig for tensile testing according to the present invention has a very simple structure and can be implemented by simply inserting one of the chuck portions 9 of the tensile testing apparatus 10, making it very economical and easy to use. Furthermore, the fixing effect of the specially machined protrusions (conical protrusions 41a, 42a and / or annular protrusions 41b, 42b) at the tips of the pressure bolts 4 (41, 42) reliably prevents the test piece 8 from shifting, thereby making it possible to obtain highly reliable test results.

[0024] Although the embodiments have been described above based on the drawings, it should be noted that the present invention is not limited to the illustrated examples, and includes the range of design modifications and application variations that would normally be made by a person skilled in the art, provided that the scope does not deviate from the technical concept of the present invention. For example, with regard to the protrusions, the present embodiment exemplifies conical protrusions 41a, 42a and annular protrusions 41b, 42b, but is not limited to this. For example, although not shown in the figures, it is of course also possible to implement a structure in which multiple conical protrusions stand in a row like a pin holder. [Explanation of symbols]

[0025] 1 Chuck mounting part 1a Roughening 2 Test piece grip 21 Clamping member 22 Clamping member 3 Jig body 4 Pressing member 41 Press bolt 41a Cone protrusion 41b Circular protuberance (circular ridge) 42 Press bolt 42a Cone protrusion 42b Circular protuberance (circular ridge) 5 Positioning member 6 Reinforcing members 8 Test Pieces 9 Chuck Part 10 Tensile testing equipment w Weld bead

Claims

1. a jig body including a chuck attachment portion to be held by one of the chuck portions of a tensile testing device for testing a test piece by holding the test piece in the chuck portion, and a test piece gripping portion into which one end of the test piece is inserted; and a pressing member for preventing the test piece inserted into the test piece gripping portion from slipping; The test piece is not subjected to any processing such as groove processing or bending processing. a pressure member that contacts the unprocessed test piece in a direction substantially perpendicular to the surface of the unprocessed test piece and applies a pressure to the unprocessed test piece; and a protrusion is formed at a tip of the pressure member that applies a pressure to the test piece while causing deformation on the surface of the test piece.

2. 2. The test piece gripping jig for a tensile test according to claim 1, further comprising a positioning member provided between said test piece gripping portion and said test piece for adjusting the position of said test piece.

3. A tensile test method using the test piece gripping jig for tensile test according to claim 1 or 2, comprising the steps of: gripping the other end of the test piece in the other chuck portion of the tensile test device; and, in a state in which one end of the test piece is inserted into the test piece gripping portion, gripping a jig body of the test piece gripping jig for tensile test by one chuck portion of the tensile test device using the chuck attachment portion. Thereafter, the pressing member is passed substantially horizontally through a hole formed in the test piece gripping portion to fix the test piece, and then a tensile test is performed.

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