JPH10170418A - Grasping tool - Google Patents

Abstract

(57) [Summary] [PROBLEMS] A gripping tool used for a material testing machine,
Even if the test piece is stretched, the gripping is surely performed and the configuration is simplified. SOLUTION: An inclined surface 2 is formed on wedge-shaped members 21R and 21L.
The wedge-shaped members 21R and 21L are slid with the inclined members 17R and 17L having the inclined surfaces 19R and 19L. Wedge-shaped member 21R,
The gripping tooth members 120R and 120L, which are composed of 21L and inclined members 17R and 17L,
3R is attached so that the interval can be separated. The test piece T is gripped by the wedge-shaped members 21R and 21L and the test piece T
When a tensile force is applied to the wedge members 21R, 21L
Move downward and approach each other, so that the test piece T does not fall out between the wedge-shaped members 21R and 21L even if the test piece T extends and its thickness decreases.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gripper for securely holding a test piece during a tensile test.

[0002]

2. Description of the Related Art Conventionally, there has been known a material testing machine which loads a test piece by gripping both ends of the test piece with a pair of left and right grip teeth provided on a pair of upper and lower grips, respectively. In this type of material testing machine, as shown in FIG. 3, a pair of grasping teeth 42R, 42L are separated from and brought into contact with a test piece by screws 45R, 45L, and the test piece is gripped.

However, when a relatively soft test piece such as rubber is gripped by such a gripper and a tensile test is performed, lateral strain is generated in the test piece due to longitudinal strain caused by elongation of the test piece, and the thickness of the test piece is increased. Becomes smaller. When the thickness of the test piece is reduced in this way, the test piece may come off from the gripper.

For this reason, as shown in FIG. 4, a pair of gripping teeth 52R and 52L are formed in a wedge shape, and
The 2R and 52L are moved up and down by a moving mechanism 55 such as an air cylinder with respect to the chuck frame 50 that gradually spreads from the entrance side to the back side along the load axis to adjust the distance between the gripping teeth 52R and 52L. Gripping tools are used. In such a gripper, when a test piece is gripped and a tensile load is applied, the gripping teeth 52
R and 52L are also pulled downward, and the chuck frame 50
And the distance between the gripping teeth 52R and 52L is reduced, so that the test piece can be reliably gripped even if the test piece is elongated and the thickness of the test piece is reduced.

[0005]

However, in the case where the gripping teeth are formed in the wedge member as described above, a mechanism for vertically moving the wedge member for gripping the test piece is required. Becomes complicated and expensive.

An object of the present invention is to provide a gripper which can hold a test piece reliably and can be constructed at low cost.

[0007]

FIG. 2 shows an embodiment of the present invention.
The invention of claim 1 is described with reference to FIG.
And a pair of gripping tooth members 120R and 120L held by a separating mechanism that separates from and separate from each other.
R, 120L opposing test piece gripping surfaces 22R, 22L
Is applied to a gripper for gripping the test piece T, and each gripping tooth member 120R, 120L moves in the load direction so that the test piece gripping surfaces 22R, 22L come closer to each other when a tensile force acts on the test piece T. Wedge-shaped members 21R, 21
The above object is achieved by being composed of L. According to the invention of claim 1, the gripping tooth members 120R, 120R,
The test piece T is gripped or released by opening and closing 120L.
When the test piece T is pulled and the wedge-shaped members 21R, 21L move in the direction of the load axis, the test piece gripping surfaces 22R, 22L come close to each other, so that a decrease in the gripping force of the test piece T is prevented.

[0008] In the section of the means for solving the above-mentioned problems, which explains the configuration of the present invention, the drawings of the embodiments of the present invention are used to make the present invention easier to understand. However, the present invention is not limited to this.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a front view showing the configuration of a material testing machine in which the grip according to the present embodiment is used. As shown in FIG. 1, in this material testing machine, the rotational force of a motor 1 is reduced by a speed reducer 2 to rotate a screw bar 3, thereby raising and lowering a cross head 4 and moving the cross head 4 with a fixed yoke 5. Upper and lower grips 6, between the side crosshead 4
The test piece T gripped by 7 is loaded.

FIG. 2A is a front sectional view showing the configuration of the gripper according to the present embodiment, and FIG. 2B is a plan view of one gripper tooth. Since the upper and lower grips 6 and 7 have the same configuration, the upper grip 6 will be described below. The gripper 6 includes a gripper body 10R, 10L and a frame 1 to which the gripper bodies 10R, 10L are attached.
It consists of 10. Here, the gripper bodies 10R, 10L
Are the same, only the gripper body 10R will be described.

The gripper main body 10R includes a cylindrical outer member 1.
Has 1R. A screw portion 12R is formed on the inner surface of the outer member 11R, and the screw member 13R is engaged with the screw portion 12R. A protrusion 14R is formed on the front end surface of the screw member 13R on the side where the test piece T is gripped, and a rotating portion 15R for rotating the screw member 13R with a hexagon wrench or the like is formed on the rear end surface. Projection 14 of screw member 13R
An intermediate member 16R is rotatably attached to R, and an inclined member 17R having an inclined surface 19R that is inclined at the front end so as to expand from the entrance side to the back side along the load axis is fixed by a pin 18R. Have been. A wedge-shaped member 21R having an inclined surface 20R that slides on the inclined surface 19R is attached to the inclined surface 19R of the inclined member 17R, and the inclined member 17R and the wedge-shaped member 21R constitute a gripping tooth member 120R. Knurls are formed on the gripping surface 22R of the wedge-shaped member 21R on the side opposite to the inclined surface 20R, and the notch recess 2 is formed above the gripping surface 22R.
3R is formed. An engaging member 24 that engages with the notch recess 23R is inserted into the notch recess 23R, and the engaging member 24 is attached to the upper part of FIG. 2 by a spring 25 provided between the engaging member 24 and the frame 110. As a result, the wedge-shaped member 21 </ b> R comes into contact with the protrusion 110 </ b> A formed on the frame 110. As shown in FIG. 2 (b), stop members 26R are fixed to both side surfaces of the inclined member 17R by screws, and the stop members 26R prevent the wedge-shaped member 21R from moving in the direction perpendicular to the paper surface. Is done.

Next, the operation of this embodiment will be described. In order to grip the test piece T by the gripper bodies 10R, 10L, the screw members 13R, 13L (13L not shown) are rotated to widen the gap between the gripping tooth members 120R, 120L. At this time, the wedge-shaped members 21R and 21L are urged upward by the spring 24,
The wedge-shaped members 21R and 21L do not move upward because they come into contact with the protruding portion 110A formed at zero. Further, since the stopper members 26R and 26L are provided, the wedge-shaped members 21R and 21L do not shift in the direction perpendicular to the plane of the drawing. After inserting the test piece T between the wedge-shaped members 21R and 21L, the test piece T is gripped by rotating the screw members 13R and 13L to bring the wedge-shaped members 21R and 21L closer to each other.

With the test piece T thus held, the motor 1 shown in FIG. 1 is driven to apply a tensile force to the test piece T. Here, since the inclined surfaces 20R and 20L of the wedge-shaped members 21R and 21L slide on the inclined surfaces 19R and 19L of the inclined members 17R and 17L in the load axis direction, a tensile force acts on the test piece T to form a wedge. When the members 21R and 21L slide downward, the distance between the gripping surfaces 22R and 22L decreases. As a result, the gripping surfaces 22R and 22L bite into the test piece T, so that the test piece T is reliably held by the wedge-shaped members 21R and 21L even if the thickness thereof is reduced by deformation.

After the test is completed, the screw members 13R, 13L are reversed to widen the distance between the wedge members 21R, 21L to remove the test piece T from the tooth members 120R, 120L. , 21L return to their original positions by the urging force of the spring 25. in this way,
In the present embodiment, when a tensile force is applied to the test piece T, the wedge-shaped members 21R, 21R,
21L moves downward to reduce the distance between the test pieces T
Is maintained, the test piece T can be reliably held even when the test piece T extends and its thickness becomes small. Further, when attaching the test piece T, it is sufficient to open and close the gripping tooth members 120R and 120L in parallel,
Since there is no need to slide the wedge-shaped members 21R and 21L up and down to reduce the interval, the test piece T can be easily gripped without generating an initial tensile force on the test piece T. Further, an elevating mechanism for vertically moving the wedge-shaped members 21R and 21L is not required, and cost can be reduced.

In the above embodiment, the knurls are formed on the gripping surfaces 22R and 22L. However, if the test piece T is an adhesive material, it is not particularly necessary to form the knurls.

In the correspondence between the above-described embodiment and the claims, the screw 13R constitutes a separating mechanism.

[0017]

As described in detail above, according to the present invention, the gripping tooth member can be opened and closed as a whole in a direction perpendicular to the load axis to grip and release the test piece. When a tensile force is applied, the wedge-shaped member moves downward and the distance between the gripping surfaces of the test specimens becomes smaller. It will not come off. Therefore, a gripper having high gripping performance can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a front view showing a configuration of a material testing machine in which a gripper according to an embodiment of the present invention is used.

FIGS. 2A and 2B show a configuration of a gripper according to an embodiment of the present invention, wherein FIG. 2A is a front view, and FIG.

FIG. 3 is a diagram showing a configuration of a conventional gripping tool.

FIG. 4 is a diagram showing a configuration of a conventional gripper.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 motor 2 reduction gear 3 screw rod 4 cross head 6,7 gripper 10R, 10L gripper body 13R screw member 17R, 17L inclined member 21R, 21L wedge-shaped member 22R, 22L gripping surface 24 engaging member 25 spring 110 frame 120R , 120L gripping tooth member

Claims (1)

[Claims] 1. A gripping tool having a pair of gripping tooth members held by a separation mechanism that separates and separates with a screw, and grips a test piece on opposing test piece gripping surfaces of each of the gripping tooth members. The gripping member is formed of a wedge-shaped member that moves in a load direction such that the test piece gripping surfaces approach each other when a tensile force is applied to the test piece.