JP2015049211A - Gripper and material testing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gripper and a material testing machine which are able to perform tensile test properly even when a deformed test piece is used.SOLUTION: An upper gripper 1 comprises: a pair of gripping tooth holders 11; and a pair of gripping teeth 12 respectively engaged with the pair of gripping tooth holders 11. A partial region of each gripping tooth 12 is inserted into a recess formed in the corresponding gripping tooth holder 11, and is movable in a direction orthogonal to a direction for applying tensile test force to each gripping tooth holder 11 by a material testing machine. Movement of the gripping tooth 12 with respect to the gripping tooth holder 11 is regulated by a plunger 21.

Description

  The present invention relates to a gripping tool for gripping an end portion of a test piece when performing a tensile test, and a material testing machine using the gripping tool.

  Such a conventional gripping tool is incorporated in, for example, a cross head of a material testing machine, and is disposed so as to face a pair of gripping teeth for holding a test piece and a tapered surface formed on the cross head. And a pair of gripping tooth holders that slide in a state where these tapered surfaces are in contact with each other. The pair of gripping teeth are inserted into the recesses formed in the corresponding gripping tooth holders from the front side, and are fixed by pressing metal fittings. The pair of gripping tooth holders are supported so as to be movable in the horizontal direction with respect to a support member that can be raised and lowered by driving a fluid cylinder. In this gripping tool, the support member is moved up and down by the fluid cylinder so that the pair of gripping tooth holders move toward each other by the action of the tapered surface, thereby gripping the test piece with the pair of gripping teeth. (See Patent Document 1).

Microfilm of actual application No. 2-80132 (Japanese Utility Model Application No. 4-38550)

  As a test piece for performing a tensile test with such a material testing machine, a test piece in which two base materials are pressed or welded may be used. In such a test piece, there are cases where the two base materials are not pressed or welded in a straight line.

  FIG. 5 is an explanatory view showing a test piece 100 in which such two base materials are pressure-welded or welded.

  FIG. 5A shows a test piece 100 in which two base materials 101 and 102 are press-contacted at a press-contact portion 103. FIG. 5B shows a test piece 100 in which two base materials 101 and 102 are welded at a welded portion 103. As shown in these drawings, in the test piece 100 in which the two base materials 101 and 102 are pressure-welded or welded, the two base materials 101 and 102 are not arranged linearly, and the base material 101 and the base material 102 And become a "<" shape, and the base material 101 and the base material 102 may have a predetermined crossing angle. In FIG. 5, this intersection angle is exaggerated.

  When a tensile test is performed on the test piece 100 as shown in FIG. 5, depending on the mounting direction of the test piece 100 with respect to the gripping tool, when the tensile force is applied to the test piece 100, the gripping teeth are changed to There is a case where a force is generated to move the holder in the direction of the holding metal. When such a force is generated, a large force is applied to the pressing metal for fixing the gripping tool, and the pressing metal may be damaged.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a gripping tool and a material testing machine capable of properly performing a tensile test even when a deformed test piece is used. And

  The invention according to claim 1 is a gripping tool for gripping an end portion of the test piece when a tensile test force is applied to the test piece to perform a tensile test. A pair of gripping teeth movable in a first movement direction that is a direction orthogonal to the direction in which the tensile test force is applied, and the pair of gripping teeth. A gripping tooth moving mechanism for moving the gripping tooth in the second moving direction between the gripping position of the test pieces close to each other and the standby position separated from each other, and the gripping tooth in the first moving direction of the gripping tooth And an urging means for urging.

  The invention according to claim 2 is the invention according to claim 1, wherein the gripping tooth holder includes a contact portion that restricts movement of the gripping tooth in the first movement direction, and the biasing means includes: The gripping teeth are biased toward the contact portion.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the urging means is a plunger.

  According to a fourth aspect of the present invention, there is provided a material testing machine for performing a tensile test by applying a tensile test force to a test piece, and a pair of grips for gripping both ends of the test piece, and the pair of grips. And a load mechanism that applies a tensile test force to the test piece by changing the distance, and at least one of the pair of grips is the grip according to claim 1 or 2.

  According to the first to fourth aspects of the present invention, when a tensile test is performed on the deformed test piece, the force to move the gripping teeth in a direction perpendicular to the direction in which the tensile test force is applied. When this occurs, the gripping teeth move in that direction relative to the gripping tooth holder. When the test force is released, the gripping tooth returns to the position before the start of the test by the action of the urging means. For this reason, even when a tensile test is performed on a deformed test piece, it is possible to appropriately execute the tensile test without applying excessive stress to the gripping tool.

1 is a schematic diagram of a material testing machine using an upper grip 1 and a lower grip 2 according to the present invention. It is a front schematic diagram of the upper gripping tool 1 according to the present invention. FIG. 5 is a partial side view showing a state in which a gripping tooth 12 is urged by a plunger 21. 2 is a schematic cross-sectional view of a plunger 21. FIG. It is explanatory drawing which shows the test piece 100 which pressure-welded or welded two base materials.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of a material testing machine using an upper grip 1 and a lower grip 2 according to the present invention.

  This material testing machine includes a pair of support columns 4 erected on a table 3 and a cross yoke 5 connecting the upper portions of these support columns 4. A screw rod (not shown) is disposed inside each column 4. Each screw rod rotates synchronously by driving a motor (not shown). The material testing machine also includes a crosshead 6 that can be moved up and down along the pair of support columns 4. Nuts are built into both ends of the crosshead 6 and these nuts are screwed into a pair of screw rods. For this reason, the cross head 6 moves up and down by the pair of screw rods rotating synchronously. On the lower surface of the cross head 6, an upper grip 1 for gripping the upper end of the test piece 100 is disposed. In addition, the table 3 is provided with a lower grip 2 for gripping the lower end of the test piece 100 via a load cell 7.

  FIG. 2 is a schematic front view of the upper gripping tool 1 according to the present invention. Here, in FIG. 2, the left half represents a side surface and the right half represents a cross section. Note that the lower gripping tool 2 has the same configuration as the upper gripping tool 1.

  The upper gripping tool 1 includes a pair of gripping tooth holders 11 and a pair of gripping teeth 12 that respectively engage with the gripping tooth holders 11. A partial region of each gripping tooth 12 is inserted into a recess formed in the corresponding gripping tooth holder 11, and a direction perpendicular to the direction in which a tensile test force is applied to each gripping tooth holder 11 by a material testing machine. It is movable in the direction perpendicular to the paper surface in FIG. 2 (first movement direction in the present invention). The movement of the gripping teeth 12 with respect to the gripping tooth holder 11 is regulated by a plunger 21 as will be described later.

  Each gripping tooth holder 11 has an inclined surface that comes into contact with the inclined surface 10 in the recess formed in the cross head 6. These gripping tooth holders 11 are supported so as to be slidable in the horizontal direction with respect to the support member 15. The position of each gripping tooth holder 11 in the direction orthogonal to the direction in which the tensile test force is applied by the material testing machine (the direction perpendicular to the paper surface in FIG. Be regulated. The pair of gripping tooth holders 11 are urged away from each other by a spring (not shown).

  A shaft 17 is connected to the support member 15. The shaft 17 is disposed in the cylinder member 18, and a piston member 16 that contacts the inner peripheral surface of the cylinder member 18 is disposed on the outer peripheral portion of the shaft 17. For this reason, this shaft 17 functions as a piston rod. When pressurized oil is supplied to the chamber 19 in the cylinder member 18, the shaft 17 moves downward together with the support member 15. When the chamber 19 in the cylinder member 18 is depressurized, the shaft 17 moves upward together with the support member 15.

  When the support member 15 moves downward, the gripping tooth holders 11 move toward each other (second movement direction in the present invention) due to the action of the inclined surfaces that contact the inclined surfaces 10 in the recesses formed in the cross head 6. ) Accordingly, the pair of gripping teeth 12 are close to each other, and the gripping teeth 12 can grip the test piece 100 shown in FIG. On the other hand, when the support member 17 moves upward, the gripping tooth holders 11 move in directions away from each other. As a result, the pair of gripping teeth 12 are also separated from each other, and the gripping of the test piece 100 is released.

  FIG. 3 is a partial side view showing a state in which the gripping teeth 12 are urged by the plunger 21 described above.

  The gripping teeth 12 that are movable with respect to the gripping tooth holder 11 are in contact with a contact portion 29 formed on the gripping tooth holder 11, thereby causing a direction perpendicular to the direction in which the tensile test force is applied (left-right direction in FIG. 3). Is restricted from moving. The surface of the gripping tooth 12 opposite to the contact surface with the contact portion 29 is in contact with the pin 24 of the plunger 21. The plunger 21 is supported by a presser fitting 22 fixed to the surface of the gripping tooth holder 11 with a screw 23.

  When exchanging the gripping teeth 12 corresponding to the test piece or the like, the presser fitting 22 is removed by operating the screw 23. Then, the gripping tooth 12 is removed from the gripping tooth holder 11 by sliding it to the front side of the material testing machine (the front side in FIG. 2 and the right side in FIG. 3). Then, another gripping tooth 12 is inserted into the recess formed in the gripping tooth holder 11 and brought into contact with the contact portion 29 of the gripping tooth holder 11, and then the presser fitting 22 is mounted again with the screw 23. By such an operation, it is possible to easily replace the gripping teeth 12.

  FIG. 4 is a schematic cross-sectional view of the plunger 21. As the plunger 21, a so-called ball plunger or a spring plunger can be used.

  The plunger 21 has a configuration in which a spring 26 that biases the pin 24 is housed in a casing 25. The pin 24 is biased leftward in FIG. 4 by the action of the spring 26.

  Due to the action of the plunger 21 and the contact portion 29 described above, the gripping tooth 12 is in front of the gripping tooth holder 11 (on the front side of the paper testing machine in FIGS. 1 and 2, and in FIG. 3). It is movable only to the right side) and is always urged in the opposite direction.

  In the material testing machine having the above configuration, when a tensile test is performed on the test piece 100 in which two base materials 101 and 102 are pressed or welded as shown in FIG. When the moving direction of the teeth 12 with respect to the gripping tooth holder 11 coincides, a force for moving the gripping teeth 12 is generated when a test force is applied to the test piece 100. If the direction of the force to move the gripping teeth 12 at this time is the direction to move the gripping teeth 12 to the front surface of the material testing machine, this force is applied to the presser fitting 22. However, according to the upper gripping tool 1 according to the present invention, the force to move the gripping teeth 12 from the test piece 100 is eliminated by the movement of the pin 24 of the plunger 21.

  That is, when the plunger 21 does not exist and the movement of the gripping teeth 12 is directly regulated by the presser fitting 22, the force for moving the gripping teeth 12 directly acts on the presser fitting 22, and the presser fitting 22 is damaged. There was a possibility of receiving. However, according to the upper gripping tool 1, the gripping tooth 12 is biased by the plunger 21, and therefore the force to move the gripping tooth 12 from the test piece 100 is the pin 24 of the plunger 21. Is resolved by moving.

  When the tensile test is completed and the tensile force on the test piece 100 is released, the gripping tooth 12 is pressed by the pin 24 by the action of the spring 26 in the plunger 21, and the gripping tooth 12 is formed in the gripping tooth holder 11. It returns to the position where it abuts against the abutting portion 29. For this reason, when the next tensile test is executed, the gripping teeth 12 have returned to the origin position, so that the next tensile test can be executed accurately.

  In the above-described embodiment, the upper grip 1 and the lower grip 2 adopt the same configuration. However, it is sufficient that at least one gripping tooth 12 of the upper gripping tool 1 or the lower gripping tool 2 is movable in a direction orthogonal to the direction in which the tensile test force is applied.

  In the above-described embodiment, one of the grip teeth 12 is brought into contact with the contact portion 29 and the plunger 21 is urged toward the contact portion by the plunger 21 from the opposite side of the contact portion 29. However, a configuration in which the gripping teeth 12 are urged by the plunger 21 from both sides may be employed.

DESCRIPTION OF SYMBOLS 1 Upper gripping tool 2 Lower gripping tool 3 Table 4 Support | pillar 5 Cross yoke 6 Cross head 7 Load cell 11 Grasp tooth holder 12 Grasp tooth 15 Support member 16 Piston member 17 Shaft 18 Cylinder member 21 Plunger 22 Holding metal 23 Screw 24 Pin 26 Spring 29 Contact part 100 Test piece 101 Base material 102 Base material

Claims (4)

When performing a tensile test by applying a tensile test force to the test piece, in the gripping tool for gripping the end of the test piece,
A pair of gripping tooth holders;
For each of the pair of gripping tooth holders, a pair of gripping teeth movable in a first movement direction that is a direction orthogonal to the direction in which the tensile test force is applied;
A gripping tooth moving mechanism for moving the pair of gripping teeth in a second moving direction between a gripping position of a test piece adjacent to each other and a standby position spaced apart from each other via the pair of gripping tooth holders;
A biasing means for biasing the gripping teeth in a first movement direction of the gripping teeth;
A gripping tool characterized by comprising: The gripping tool according to claim 1,
The gripping tooth holder includes a contact portion that regulates movement of the gripping tooth in the first movement direction,
The biasing means is a gripping tool that biases the gripping teeth toward the contact portion. The gripping tool according to claim 1 or 2,
The urging means is a gripper that is a plunger. In a material testing machine that applies a tensile test force to a test piece and performs a tensile test,
A pair of grips for gripping both ends of the test piece;
A load mechanism for applying a tensile test force to the test piece by changing a distance between the pair of gripping tools;
With
The material testing machine according to claim 1, wherein at least one of the pair of grips is the grip according to claim 1.

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