JP2521660Y2 - Material testing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a material testing machine having a test piece gripper for holding a test piece with a pair of fluid pressure cylinders.

B. Conventional Technology Conventionally, a grip shown in FIG. 3 has been known as a grip for gripping a test piece with a pair of fluid pressure cylinders.

In FIG. 3, the grip shown by the general reference numeral 1 includes a gate-shaped grip body 2, a pair of fluid pressure cylinders 3 and 4, and a pair of test piece gripping teeth 5 and 6.

The fluid pressure cylinders 3 and 4 are arranged inside both ends of the gate-type grip body 2 with their axes aligned in the horizontal direction, and the cylinder bodies are integrally fixed to both ends of the grip body 2. Further, the piston rods 3a, 4a of the fluid pressure cylinders 3, 4 are projected so that their axes coincide with each other in opposite directions, and the gripping teeth 5, 6 for gripping the test piece 7 from the left and right oscillate at the projecting ends. It is possible to install.

When gripping the test piece 7 in the gripping tool configured as described above, first, fluid pressure is supplied to the rod side chambers of the fluid pressure cylinders 3 and 4 to retract the piston rods 3a and 4a, and the gripping teeth 5 and Keep 6 open. When the test piece 7 is inserted between the gripping teeth 5 and 6 in this state and fluid pressure is supplied to the head side chamber of the fluid pressure cylinders 3 and 4, the piston rods 3a and 4a and the gripping teeth 5 and 6 move forward. The test piece 7 is clamped and held. The gripping force of the test piece 7 is determined by the fluid pressure supplied to the head side chamber of the fluid pressure cylinders 3, 4.

C. Problem to be Solved by the Invention In such a conventional test piece gripping tool, the central axis 8 of the piston rods 3a, 4a is fixed at a right angle to the test piece 7, and the gripping teeth 5, 6 are used to Since the gripping force is determined by the fluid pressure supplied to the fluid pressure cylinders 3 and 4, in order to reliably grip the test piece, it is supplied to the head side chamber of the fluid pressure cylinders 3 and 4 as the load force F increases. It is necessary to increase the fluid pressure to increase the pressing force P on the test piece 7.

Therefore, when the applied load becomes large, the pressure source becomes large, and the cylinders 3 and 4 also become large, resulting in a heavy weight of the grip and an increase in cost.

The technical problem of the present invention is to generate a large gripping force with a low fluid pressure.

D. Means for Solving the Problems The present invention will be described with reference to FIG. 1 showing an embodiment. The material testing machine according to the present invention is provided with a gate type grip body 10
And a pair of fluid pressure cylinders 12 and 13 that are swingably connected to the left and right sides of the grip body 10 so as to face each other, and a piston rod 1 that projects from the swinging end sides of the fluid pressure cylinders 12 and 13.
Specimen gripping teeth 18 and 19 attached to 2b and 13b, respectively
And each of the fluid pressure cylinders 12 and 13 is gripped by its axis L1 and L2.
And a means 22 to 25 for biasing the test piece 7 clamped by 18, 19 so as to incline in a direction opposite to the direction of the load applied to the test piece 7.

E. Action Since the left and right fluid pressure cylinders 3 and 4 swingably supported by the grip body 10 are arranged so as to be inclined upward with respect to the tensile force acting direction of the test piece 7, the fluid pressure cylinder 3 and When a tensile force acts on the test piece 7 that is gripped by the fluid pressure supplied to 4, the gripping force increases due to the wedge effect.

As a result, even if the fluid pressure supplied to the fluid pressure cylinder is the same as in the conventional case, a gripping force adapted to a large tensile force can be generated, and the test piece can be reliably gripped.

It should be noted that, in the above D and E for explaining the configuration of the present invention, the drawings of the embodiments are used to make the present invention easy to understand, but the present invention is not limited to the embodiments.

F. Example Hereinafter, an example in which the present invention is applied to a material testing machine having a grip for a tensile test will be described with reference to FIGS. 1 and 2.

In FIG. 1 and FIG. 2, 10 is a gate-shaped gripping tool body, and this gripping tool body 10 has a rod 11 protruding in the middle of the horizontal portion thereof, such as a crosshead of a tester body not shown. Connected to.

The grip body 10 is provided with a pair of fluid pressure cylinders 12 and 13 that oppose the vertical portions 10a and 10b at the left and right ends of the grip body 10 so as to be vertically swingable. The fluid pressure (pneumatic or hydraulic) cylinders 12, 13 are provided with support portions 14, 15 on the head side end surfaces of the cylinder tubes 12a, 13a.
Cylinders 12 and 13 are swingably supported by the grip body 10 by rotatably connecting 15 to the inside of the vertical portions 10a and 10b by pins 16 and 17.

In addition, the test piece 7 is attached to the tips of the piston rods 12b and 13b.
The gripping teeth 18, 19 for sandwiching the left and right sides are pivotally attached by pins 20, 21 so as to be swingable. Further, one ends of tension springs 22, 23 and 24, 25 for lifting the swinging end sides of the fluid pressure cylinders 12, 13 including the gripping teeth 18, 19 are connected to both ends of the pins 20, 21, respectively. Further, the other ends of the tension springs 22, 23 and 24, 25 are connected to the horizontal portion of the grip body 10.

In this way, by supporting the oscillating end sides of the fluid pressure cylinders 12 and 13 with the tension springs 22, 23 and 24, 25, respectively, the axes L1 and L2 of the fluid pressure cylinders 12 and 13 are centered around the pins 16 and 17, respectively. Then, it is tilted upward at a predetermined angle α with respect to the axis L3 connecting between the pins 16 and 17. Then, the upper end surfaces of the gripping teeth 18, 19 are brought into contact with a horizontal guide surface 26 formed on the lower surface of the horizontal portion of the gripping tool main body 10, and the gripping teeth 18, 19 are moved to the fluid pressure cylinders 12, 13.
It can move horizontally as it moves forward and backward.

The cylinder tube 12a of the fluid pressure cylinder 12 is formed with fluid inlets / outlets 27, 28 which communicate with the head side pressure chamber 12d and the rod side pressure chamber 12e defined by the piston 12c. Further, the cylinder tube 13a of the fluid pressure cylinder 13 is provided with fluid outflow / outflow ports 29, 30 communicating with the head side pressure chamber 13d and the rod side pressure chamber 13e defined by the piston 13c. Ports for these fluids 2
7, 28 and 29, 30 are connected to a fluid pressure supply source (not shown) via a switching control valve not shown.

 Next, the operation will be described.

When releasing the gripped test piece 7 as shown in FIG. 1, the switching control valve (not shown) is operated to open the head side pressure chambers 12d and 13d of the fluid pressure cylinders 12 and 13 to the atmosphere or the tank. , The rod side pressure chambers 12e, 13e are connected to a fluid pressure supply source to supply the pressure fluid to the rod side pressure chambers 12e, 13e. As a result, the pistons 12c, 1 of each fluid pressure cylinder 12, 13
When the 3c moves backward, the gripping teeth 18,19 connected via the piston rods 12b, 13b also move backward, so that the gripping teeth 18,19
The test piece 7 gripped by is released.

Further, when gripping the test piece 7, the test piece 7 is positioned between the gripping teeth 18 and 19 in the open state, and the switching control valve (not shown) is switched to switch the rod side pressure chamber 12e of each fluid pressure cylinder 12 and 13. , 13e are opened to the atmosphere or the tank, and the head side pressure chambers 12d, 13d are connected to the fluid pressure supply source. Since the pressure fluid from the fluid pressure supply source is supplied to the head side pressure chambers 12d and 13d, the pistons 12c and 13c move forward and at the same time the gripping teeth 18,
19 also advances along the guide surface 26 and clamps the test piece 7 from both left and right sides. When the test piece 7 is completely gripped, the fluid pressure between the head side pressure chambers 12d and 13d is held at the set pressure by the pressure holding circuit (not shown) of the fluid pressure system.

On the other hand, when the tensile force F acts on the test piece 7 in the gripped state, the rocking end side of both fluid pressure cylinders 12, 13 holding the test piece 7 in the state of being inclined upward at the angle α causes the pin 16,
Attempts to rotate downward with 17 as the fulcrum. Therefore, the wedge effect increases the gripping force, and the fluid pressure cylinders 12, 13
The test piece 7 can be gripped with a gripping force equal to or higher than the fluid pressure supplied to the test piece 7.

Therefore, in this embodiment, the test piece gripping force equivalent to that of the conventional one can be generated with a lower fluid pressure, the capacity of the fluid pressure source can be reduced, and the fluid pressure system including the pressure source can be reduced. The cost can be reduced, and the grasping tool including the fluid pressure cylinders 12 and 13 can be easily reduced in weight and size.

The material testing machine according to the present invention is not limited to the structure shown in the above embodiment, and can be arbitrarily modified within the scope of the claims. It can also be applied to a compression test gripping device. Further, the inclination urging means is not limited to the coil spring, and an elastic body may be interposed in the cylinder support structure.

G. Effect of the Invention Since the present invention is as described above, if the fluid pressure supplied to the fluid pressure cylinder is the same, a larger gripping force than the conventional one can be generated. As a result, there is an effect that it contributes to downsizing and weight saving of the gripping tool, and also enables cost reduction of the pressure source.

[Brief description of drawings]

FIG. 1 is a front view of a material testing machine according to an embodiment of the present invention with a part of a gripping tool cut away. FIG. 2 is a bottom view of FIG. FIG. 3 is a front view of a conventional test piece gripping tool. 10: Grip body, 12, 13: Fluid pressure cylinder 18, 19: Grip teeth 22-25: Tension spring (tilt biasing means)

Claims (1)

(57) [Scope of utility model registration request] 1. A gate-shaped grip body, a pair of fluid pressure cylinders that are swingably connected to opposite left and right sides of the grip body, and swing end sides of the fluid pressure cylinders. Of the test piece grippingly mounted on the piston rod protruding from the test piece and the axis of each fluid pressure cylinder is tilted in the opposite direction to the load direction of the test piece clamped and held by the gripping tooth. And a biasing means for urging the test piece gripping tool.