JP3125873U - Grasping tool - Google Patents

Abstract

An object of the present invention is to eliminate play caused by slip generated in a gripper during a material test.
SOLUTION: A pair of gripping teeth 2 and 3 are provided with two pin through holes separated in the horizontal direction, and two pins 4 and 4 are passed through the opposing pin through holes, and the pins 4 and 4 are moved back and forth. Opening and fixing to both sides of the gripper main body 5 opening downward. Pressing plates 9 and 9 for pressing the gripping teeth 2 and 3 are arranged on the upper side of the gripping teeth 2 and 3, and a gripping tooth presser bolt 8 for pressing the gripping teeth 2 and a pin rattling removing bolt 10 for pressing the pressing plates 9 and 9. 10 is screwed.
[Selection] Figure 1

Description

  The present invention relates to a grip used for a material testing machine, and more particularly to a grip for improving test accuracy by reducing test piece mounting play generated during a test.

Conventionally, a wedge-shaped gripper as shown in FIG. 7 is generally used for a tensile test of a material testing machine. This wedge-shaped gripping tool 21 is provided with a pair of left and right wedge-shaped gripping teeth 23 and 24 for clamping a test piece from both sides to a gripping body 22 having a wedge action surface formed on the inside thereof. The end is supported by a support shaft 25 attached to the tester main body, and the grip nut body 22 is rotated by rotating a cap nut 27 screwed to a screw rod portion 26 provided at the rear end of the grip body 22. A clamping force is indirectly applied to the gripping teeth 23 and 24 by moving up and down along the support shaft 25 (see Patent Document 1). In this wedge-shaped gripping tool 21, the rotational torque applied to the cap nut 27 is converted into a horizontal clamping force and transmitted, so that the shape of the mechanism portion is increased to increase the strength in order to maintain the necessary clamping force. There was a need. For this reason, a pin type gripping tool 30 as shown in FIG. In this gripping tool, a pin 32 supported by the gripping tool body 31 is passed through pin through holes 33a, 34a formed in the left and right gripping teeth 33, 34, and the gripping teeth are pressed by a push screw 35 screwed to the gripping tool body 31. 33 and 34 are pushed from the left and right with a push screw 35 so as to sandwich the test piece TP.
JP-A-5-232000

  In the pin type gripping tool 30, a clearance is provided between the pin through holes 33 a, 34 a formed in the gripping teeth 33, 34 and the pin 32, so that the left and right gripping teeth 33, 34 are pushed by the push screw 35. When the piece TP is clamped, there is a gap around the pin 32, and there is a problem that rattling of the grip caused by the narrowing of the gap in the process of the test causes a sudden change in the test data. This is particularly noticeable when conducting a fatigue test in which tensile and compressive forces are applied to the specimen.

The gripping tool of the present invention has a gripping tool body formed with gripping frames on both sides, two pins disposed between the gripping frames, and a test piece through which the two pins penetrate. And a pair of gripping teeth for gripping and gripping teeth pressing means for pressing both the gripping teeth against the pin.
Further, the gripping tooth pressing means is disposed between the upper part of the gripping tooth and the upper inner wall of the gripping tool main body, and is screwed to the upper inner wall of the gripping tool main body so as to apply a downward pressing force to the pressing plate. It is composed of a pin rattling bolt that eliminates the clearance between the pin upper portion and the pressing plate.

  Since the gripping teeth move in parallel with the two pins as a guide and pinch the test piece, the gripping force is not applied to the test piece, and the upper gap between the gripping tooth and the pin holds the gripping tooth. Since it is removed by pressing the rattling member provided at the top of the test piece, sudden changes in the test data are not seen during the test, improving the accuracy of the test data and making it easy to set the test piece to the grip Yes.

  An embodiment of a gripping tool according to an embodiment of the present invention will be described in detail with reference to the drawings. 1 is a front view showing the structure of a gripping tool according to an embodiment of the present invention, FIG. 2 is a side view of the gripping tool, FIG. 3 is a top view of the gripping tool, and FIG. 4 is a block diagram of a material testing machine in which the gripping tool is used. FIG. 5 is a diagram showing the gap between the gripping teeth and the pins in the test piece mounting diagram (A) and the mounting end diagram (B).

  In this gripping tool 1, two pins 4 and 4 are passed through a pair of left and right gripping teeth 2 and 3 having tooth surfaces 2a and 3a for holding a test piece TP, and the gripping teeth 2 and 3 are connected to pins 4 and 4 respectively. This is a pin-type gripping tool 1 that is slidable and pressed and clamped in a state where a test piece TP is sandwiched.

  This grip 1 is opened in the front-rear direction and opened downward, and each component is incorporated in a rectangular grip body 5 having a screw hole 5a for screwing into the load cell 18 at the top. The pin 4 has a hexagonal head 4a at one end and a threaded portion 4b at the other end. The threaded portion 4b is inserted from the left side toward the gripper body 5 and passed through the gripping teeth 2, 3 and the spacer 6, and then a nut 7 is screwed onto the threaded portion 4b projecting to the right side so that the pin 4 is attached. It is fixed to the grip body 5. The spacer 6 is of such a thickness that the test piece TP is clamped at the approximate center of the gripper body 5 when viewed from the front. The spacer 6 is prepared each time corresponding to the thickness of the test piece TP, or one prepared in advance is selected and used. Further, a gripping-holding bolt 8 for pushing the gripping teeth 2 is screwed to the left side of the gripping tool main body 5, and pressing plates 9, 9 disposed on the front and back of the gripping teeth 2, 3 on the top. The pin rattle-removing bolts 10 and 10 are screwed onto the gripping teeth 2 and 3. When pushing the gripping teeth 2 with the gripping-holding bolt 8 in the gripping tool 1, an outward force is applied to the left side of the gripping tool body 5, but the width of both sides is fixed by the head 4 a and the nut 7 of the pin 4. Therefore, deformation is suppressed. As a result, a light metal material such as an aluminum alloy can be used as the material of the gripper body 5 in addition to steel and stainless steel.

  As shown in FIG. 4, the material testing machine 11 in which the gripping tool 1 of the present invention is used includes a base 12, a pair of left and right screw struts 13 and 14 standing on the left and right ends thereof, and a screw strut comprising an upper yoke 15. Detection signals from the assembly part, the cross head 16 that is screwed up and down with the screw struts 13 and 14, the screw strut driving part 17 composed of a motor and gear installed in the base 12, and the load cell 18 It is comprised from the arithmetic processing part 19 converted into test force, and a test force is displayed and recorded.

  Next, the procedure for clamping the test piece TP to the gripping tool 1 attached to the load cell 18 fixed to the crosshead 16 of the material testing machine 11 and the operation associated therewith will be described below with reference to FIGS. To do. In addition, the grip 1 fixed to the base 12 side is only attached upside down, and the procedure and operation are the same.

  First, a spacer 6 suitable for the test piece TP is prepared, and the pins 4 and 4 are passed through the gripping teeth 2 and 3 and a hole formed in the spacer 6, and a nut 7 is screwed and fixed to the gripper main body 5. Next, the test piece TP is inserted between the gripping teeth 2 and 3 in a state where the gripping-holding bolt 8 is loosened, and the gripping-holding bolt 8 is screwed to clamp the test piece TP between the gripping teeth 2 and 3. In this state, for example, a gap G1 and a gap G2 are generated between the gripping teeth 2 and the upper portions of the pins 4 and 4 as shown in FIG. When the pinch bolts 10 and 10 are turned in this state to apply force F in the direction of the arrow to the pressing plates 9 and 9, the upper portions of the gripping teeth 2 and 3 are aligned as shown in FIG. The upper clearances G1 and G2 are eliminated. Next, the crosshead 16 is lowered and the lower side of the test piece TP is inserted between the gripping teeth 2 and 3 of the gripping tool 1 on the base 12 side, and then the test piece TP is clamped in the same procedure as described above. When the tensile test is performed by gradually raising the crosshead 16 after the completion of the test piece TP attachment, there is no clearance between the upper portions of the pins 4 and 4 and the gripping teeth 2 and 3, so that the gripping teeth 2 and 3 for the pins 4 and 4 are used. Sliding does not occur. Thereby, a tensile test is performed without generating play in the movement of the test piece TP.

  The pin type gripping tool of the present invention is more suitable for use in a test in which a tensile force and a compressive force are alternately applied to a test piece, that is, a fatigue test in which a vibration load is applied. Since there is no play between the grip body and the grip teeth, it can be used as a grip for swinging.

  FIG. 6 is a front view (A) and a side view (B) showing the configuration of a gripping tool 1A according to another embodiment. This tension gripping tool 1A is obtained by screwing a gripping-holding bolt 8A on the right side of the gripping tool main body 5A instead of the spacer 6. The gripping teeth holding bolts 8 and 8A are screwed in advance so that the longitudinal center axis of the test piece TP is directed to substantially the center of the gripping tool body 5A, and the gripping teeth 2 and 3 hold the test piece TP. The spacer 6 can be omitted by using the gripping bolts 8 and 8A.

  Used for material testing machine grips.

It is a front view which shows the structure of the holding tool by the Example of this invention. It is a side view of the holding tool of an Example. It is a top view of the holding tool of an Example. It is a block diagram of the material testing machine in which a holding tool is used. It is a clearance gap state figure (A) and pin gap removal state figure (B) between the pin at the time of the test piece attachment by an Example, and a gripping tooth member. It is the front view (A) and side view (B) which show the structure of the holding tool by another Example. It is a figure which shows the structural example of the conventional wedge-shaped holding tool. It is a figure which shows the structural example of the conventional pin type grip.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Grab 1A Grab 2 Grab 2a Tooth surface 3 Grab 3a Tooth surface 4 Pin 4a Head 4b Thread part 5 Grab body 5A Grab body 5a Screw hole 6 Spacer 7 Nut 8 Grasp tooth bolt 8A Grasp DESCRIPTION OF SYMBOLS 9 Pressing plate 10 Pin ratchet bolt 11 Material testing machine 12 Base 13 Screw support 14 Screw support 15 Upper yoke 16 Crosshead 17 Screw support 17 Load cell 19 Computation processing part 21 Wedge-shaped gripping body 22 Grasping tooth 24 Grasping Teeth 25 Support shaft 26 Threaded rod portion 27 Cap nut 30 Pin type gripper 31 Grasping tool body 32 Pin 33 Grasp tooth 33a Pin through hole 34 Grasp tooth 34a Pin through hole 35 Push screw

Claims (2)

A gripping tool main body formed with gripping frames on both sides, two pins disposed between the gripping frames, and the two pins penetrating and holding a test piece by holding A gripping tool comprising a pair of gripping teeth and a gripping tooth pressing means for pressing both the gripping teeth against the pin. The pin that presses the gripping tooth pressing means between the upper part of the gripping tooth and the inner wall of the upper part of the gripper body, and is screwed to the inner wall of the upper part of the gripper body to apply a downward pressing force to the pressing plate. The gripping tool according to claim 1, wherein the gripping tool is constituted by a pinch removing bolt that eliminates a gap between the upper portion and the pressing plate.

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