JPH05332902A - Material testing machine - Google Patents

Abstract

(57) [Summary] [Purpose] Even if the cross-sectional size of the test piece changes, the wedge teeth are held at a fixed position with respect to the test piece, and a compressive load is not applied to the test piece during gripping. [Structure] A pair of initial tightening fluid pressure cylinders 13 and 14 symmetrically mounted in the grip body 10 on an axis orthogonal to the load axis X with a space 101 therebetween, and tips of piston rods 13c and 14c thereof. By the guide members 16 and 17 provided with taper on the operation cylinder 1 also serving as a damper
The test piece TP whose orientation value is supported by 5 is grasped from both sides, and then the switching valve 18 closes the fluid pressure circuit to hold the fluid pressure cylinders 13 and 14 in a blocked state. Then, the test piece TP is clamped and gripped by the wedge action of the wedge teeth 11 and 12 generated in proportion to the tensile load.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material testing machine provided with a wedge type gripping tool for operating wedge teeth using a hydraulic cylinder to grip a test piece.

[0002]

2. Description of the Related Art Conventionally, as a material testing machine equipped with a fluid pressure type grip, for example, Japanese Utility Model Laid-Open No. 61-193356, Japanese Utility Model Laid-Open No. 3-28446, and Japanese Utility Model Laid-Open No. 4-3855.
The one disclosed in Japanese Patent No. 0 is known.

As shown in FIG. 2, the grip shown in Japanese Utility Model Laid-Open No. 61-193356 discloses a pair of grips provided on both sides 31a and 31b of a main body 31 of the gate-shaped grip so that their axes are aligned in the horizontal direction. The fluid pressure cylinders 32 and 33 and the piston rods 32a and 33 of the fluid pressure cylinders 32 and 33, respectively.
The gripping teeth 34 and 35 attached to the tip of a face to face each other are provided, and the gripping teeth 34 and 35 are moved in the directions approaching each other by the respective fluid pressure cylinders 32 and 33 to move the test piece TP from both sides. Clamp and grip. The gripping force of the test piece TP at this time is due to the fluid pressure cylinders 32, 33.
Determined by the fluid pressure supplied to the.

As shown in FIG. 3, the grasping tool disclosed in Japanese Utility Model Laid-Open No. 3-28446 has a pair of left and right side portions 41a and 41b of a gate-type grasping tool body 41 which are swingably mounted in a pulling direction of a test piece. Fluid pressure cylinders 42 and 43 and piston rods 42a and 4 of these fluid pressure cylinders 42 and 43.
Test piece gripping teeth 4 attached to 3a so as to be swingable
4, 45, and the fluid pressure cylinders 42, 43 for the test piece TP
Springs 46, 4 for biasing and tilting in the direction opposite to the pulling direction of
7 and 7. Test piece TP is each fluid pressure cylinder 4
It is gripped by the gripping teeth 44 and 45 when the members 2 and 43 are extended. Then, the gripping force on the test piece TP increases in response to the tensile force acting on the test piece TP by blocking the bottom chambers of the fluid pressure cylinders 42 and 43.

As shown in FIG. 4, the gripping tool disclosed in Japanese Utility Model Laid-Open No. 4-38550 is inclined to the opposite tapered surfaces 59 and 60 of the inverted ladder-shaped tapered holes formed in the supporting member such as the crosshead 51. Holding tooth holders 52, 53 movably attached along the direction, a fluid pressure cylinder 54 for integrally operating the holding tooth holders 52, 53 along a tapered surface, and a pair of holding tooth holders 52, 53.
The gripping teeth 5 housed inside and supported by springs 55, 56
7, 58, and the gripping teeth holders 57, 5 by moving the gripping tooth holders 52, 53 up and down with the fluid pressure cylinder 54.
8 is opened, and the test piece TP is gripped by the gripping teeth 57 and 58. Then, the gripping force of the test piece TP increases due to the wedge effect of the gripping teeth 57 and 58 when the tensile force acts on the test piece TP.

[0006]

However, in the grip shown in FIG. 2 shown in Japanese Utility Model Laid-Open No. 61-193356,
Since the gripping force of the test piece TP by the gripping teeth 34, 35 is determined by the fluid pressure supplied to the fluid pressure cylinders 32, 33, for example, in order to reliably grip the test piece TP on which a tensile load acts, the fluid pressure is required. There is a problem that the fluid pressure supplied to the cylinders 32 and 33 must be increased, a high-pressure pump is required, and the fluid pressure cylinder becomes large and the grip becomes heavy. Further, when the test piece TP breaks during the tensile test, the breaking shock acts on the gripping tool, and there is a problem that the test results are disturbed.

On the other hand, in the grasping tool shown in FIG. 3 of Japanese Utility Model Laid-Open No. 3-28446, when the tensile force acts on the test piece TP, the fluid pressure cylinders 42 and 43 make the fulcrum 48,
The test piece T is oscillated in the clockwise direction and the counterclockwise direction about 49, respectively, and the bottom pressure thereof is increased.
Since the gripping force on P increases, the fluid pressure cylinder 4
It is not necessary to increase the fluid pressure supplied to 2, 43 according to the tensile force applied to the test piece TP. However,
Since the fluid pressure cylinders 42 and 43 have to be configured separately from the grip body 41 to be swingably supported by the grip body 41, there is a problem that the structure becomes complicated and the grip becomes large.

In the gripper shown in FIG. 4 shown in Japanese Utility Model Laid-Open No. 4-38550, the gripping tooth holders 52 and 53 are moved by the fluid pressure cylinder 54 along the tapered surfaces 59 and 60 of the support member 51 in the test piece pulling direction. As a result, the test piece TP is clamped and gripped. Therefore, when the cross-sectional size of the test piece TP changes, the positions of the gripping teeth 57 and 58 change in the load axis direction of the test piece TP. As a result, there is a problem that the gripping position with respect to the test piece TP changes, the length of the portion under test of the test piece TP cannot be made constant, and a compressive load may be applied to the test piece TP during gripping.

An object of the present invention is to provide a material testing machine capable of keeping the gripping positions of the wedge teeth on the test piece constant even when the cross-sectional size of the test piece is changed and preventing a compressive load from being applied to the test piece during gripping. To provide.

[0010]

The present invention will be described with reference to FIG. 1 which is one embodiment. The present invention is a material testing machine equipped with grippers 1 and 2 for gripping both ends of a test piece TP. Applied to. And the above-mentioned purpose is to grasp the grippers 1 and 2,
The support member 10, a pair of initial tightening fluid pressure cylinders 13 and 14 mounted symmetrically on the support member 10 on an axis orthogonal to the load axis X with the load axis interposed therebetween, and the fluid pressure cylinders 13 and 14. A pair of guide members 16 and 17 provided on the piston rods 13c and 14c and having tapered surfaces that are symmetrically inclined in the load axis X direction, and a pair of wedges that slide along the tapered surfaces of the guide members 16 and 17, respectively. The teeth 11 and 12 and the wedge teeth 11 mounted on the support member 10 so as to allow movement in a direction orthogonal to the load axis.
Fluid pressure cylinder 1 for positioning 12 in the load axis X direction
This is achieved by constructing 5 and 5.

[0011]

When the fluid pressure cylinder 15 is moved back and forth, the positions of the wedge teeth 11 and 12 in the direction of the load axis X change, and the gripping position for the test piece TP can be adjusted. Then, when the initial tightening fluid pressure cylinders 13 and 14 are moved forward, the wedge teeth 11 and 12 grip the test piece TP from both sides while maintaining the adjusted gripping position. This eliminates the position change of the wedge teeth 11 and 12 in the load axis X direction during the gripping operation, and eliminates the compressive load on the test piece TP during gripping. After the initial tightening, the fluid pressure cylinder 13,
By blocking 14, the reaction force generated by the wedge action when the test piece TP is loaded can be supported by the fluid pressure cylinders 13 and 14 in the blocked state. Further, the shock at break can be absorbed by the fluid pressure cylinder 15.

Incidentally, in the section of means and action for solving the above problems for explaining the constitution of the present invention, the drawings of the embodiments are used for making the present invention easy to understand. It is not limited to.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. In FIG. 1, 1 is an upper gripping tool for gripping one end of a test piece TP, 2 is a lower gripping tool for gripping the other end of a test piece TP, and these grips move vertically along a load axis X. Will be placed. The upper grip 1 is suspended by a pull rod 3 on an upper crosshead (not shown) of the material testing machine. Further, the lower grip 2 is connected to the table of the material testing machine or the lower crosshead (both not shown) by the rod 4.

Next, details of the gripping tool will be described. Since both grips 1 and 2 have the same structure, the upper grip 1
Will be described. The grip 1 includes a grip body 10,
A pair of wedge teeth 11 and 12 for gripping the test piece TP, a pair of initial tightening fluid pressure cylinders 13 and 14 for applying an initial gripping force to the wedge teeth 11 and 12, and the wedge teeth 11 and 12.
Is provided with a fluid pressure cylinder 15 for lifting and lowering a wedge which adjusts and determines the position in the load axis direction and also serves as a breaking impact damper.

The grip body 10 has a concave space 101 in the middle of the side facing the test piece TP.
The pull rod 3 is fixed to the center of the end surface opposite to 01. The fluid pressure cylinders 13 and 14 for initial tightening are respectively built in both ends of the grip body 10 facing each other with the space 101 interposed therebetween, and the shafts orthogonal to the load axis X are provided in both ends of the grip body 10. Cylinder bores 13a and 14a formed symmetrically on the line with the space 101 interposed therebetween, pistons 13b and 14b housed in the cylinder bores 13a and 14a, and integrally connected to the pistons 13b and 14b, respectively. It is composed of piston rods 13c and 14c. Further, the tapered guide member 16, at the tip of the protrusion of the piston rods 13c, 14c into the space 101,
17 are provided. This tapered guide member 16,
A taper surface is formed on the tip end surface of 17 so as to gradually widen from the entrance side of the space 101 toward the back. Wedge teeth 11 and 12 slidably contact the tapered surfaces of the guide members 16 and 17, respectively, along the tapered surfaces. Further, the head side chamber and the rod side chamber of the fluid pressure cylinders 13 and 14 can be switched to a fluid pressure pump P and a hydraulic tank T via a three-position switching valve 18.

The wedge lifting / lowering fluid pressure cylinder 15 is mounted on the inner side of the space 101 in the grip body 10 so as to coincide with the load axis X, and the wedge lifting / lowering fluid pressure cylinder 15 space. A wedge tooth support member 19 is provided at the tip of the piston rod 15a protruding into the portion 101, and the wedge teeth 11 and 12 are supported by the support member 19 so as to be slidable in the left-right direction orthogonal to the load axis line X. ing. The wedge members 11 and 12 are constantly urged in the opening direction by a spring member (not shown).

Next, the operation will be described. When gripping the test piece TP, the switching valve 18 is switched to the B position, the pressure fluid from the pump P is supplied to the rod side chambers of the cylinder bores 13a and 14a, and the pistons 13b and 14b are retracted to cause the wedge teeth 11 ,. Keep 12 open. When the wedge lifting / lowering fluid pressure cylinder 15 is operated in the forward or backward direction, the wedge teeth 11 and 12 move in the arrow direction of FIG. Thereby, the grip position of the test piece TP in the load axis direction is adjusted. If the upper and lower cylinder chambers of the wedge lifting fluid pressure cylinder 15 are blocked in this state,
The positions of the wedge teeth 11 and 12 are fixed. Wedge tooth 1
In the state in which the test pieces 1 and 12 are opened, the both ends of the test piece TP are connected to the wedge teeth 11 and 12 of the upper and lower grips 1 and 2, respectively.
Insert in between. After that, the switching valve 18 is switched to the C position to transfer the pressure fluid from the pump P to the cylinder bores 13a, 1a.
It is supplied to the bottom side chamber of 4a, and the pistons 13b and 14b are operated in the forward direction in which they approach each other. Along with this, the wedge teeth 11 and 12 also move forward integrally with the pistons 13b and 14b, and grip the end portion of the test piece TP from the left and right with a force corresponding to the fluid pressure from the pump P. At this time, the wedge tooth 11,
The vertical position of 12 is a wedge hydraulic cylinder 1 for lifting and lowering.
Since it is fixed at 5, the wedge teeth 11 and 12 move only to the left and right. When the test piece TP is gripped, the switching valve 18 is switched to the A position and the cylinder bores 13a, 14 are formed.
The rod side chamber and the head side chamber of a are completely closed to hold the fluid pressure cylinders 13 and 14 in a blocked state.

When a tensile load is applied to the test piece TP held by the upper and lower grippers 1 and 2, the tensile load also acts on the wedge teeth 11 and 12. As a result, since the wedge teeth 11 and 12 bite between the tapered surfaces of the guide members 16 and 17 while holding the test piece TP,
The reaction force generated by the wedge action is the fluid pressure cylinder 1.
Acts on the bottom chambers of 3, 14, but the cylinder bore 13
A switching valve 18 is provided for the rod side chamber and the bottom side chamber of a and 14a.
Since it is completely closed and blocked by, the reaction force can be supported by the fluid pressure cylinders 13 and 14.
Eventually, the gripping force of the test piece TP due to the wedge action increases in proportion to the tensile load.

When the test piece TP is broken, the wedge teeth 11 and 12 are moved in the opening direction by the reaction force at the time of breaking, and are absorbed by the wedge lifting hydraulic cylinder 15. Therefore, the fluid pressure cylinder 13 for initial tightening,
No breaking shock is applied to 14. During the test, both cylinder chambers of the wedge lifting fluid pressure cylinder 15 are blocked by valves (not shown).

Next, when the gripped test piece TP is opened, the switching valve 18 is switched to the B position. Switching valve 18 is B
When switched to the position, the bottom side chambers of the fluid pressure cylinders 13 and 14 are opened to the tank T, and the pressure fluid is supplied from the pump P to the rod side chambers. For this reason, the pistons 13b and 14b of the fluid pressure cylinders 13 and 14 are operated in the backward direction in which they are separated from each other, and the wedge teeth 11 and 12 are opened.
As a result, the test piece TP held by the gripping teeth 11 and 12
Is released.

The gripper according to this embodiment as described above is
A pair of initial tightening fluid pressure cylinders 13 and 14 symmetrically mounted on the axis line orthogonal to the load axis line X in the grip body 10 with the space 101 interposed therebetween, and a tapered guide provided at the tip of the piston rod. The members 16 and 17 and the wedge teeth 11 and 12 whose positions are determined by the wedge lifting / lowering fluid pressure cylinders 15 and which are movably supported to the left and right, are wedged by the initial tightening fluid pressure cylinders 13 and 14. Since the teeth 11 and 12 are moved only in the closing direction to grip the test piece from the direction orthogonal to the load axis X, the position of the wedge tooth in the load axis direction changes even if the cross-sectional size of the test piece changes. The gripping position of the wedge tooth with respect to the test piece can be made constant. For this reason, no compressive load is applied to the test piece during gripping. Further, after the test piece is initially tightened by the fluid pressure cylinders 13 and 14, the fluid circuit of this fluid pressure cylinder is blocked by the switching valve 18, and in this state, the tapered guide member 1 which is generated when a tensile load is applied.
Since the gripping force of the test piece is increased by the wedge action of the teeth 6, 6 and the wedge teeth 11, 12, the gripping force of the test piece can be generated even with a low fluid pressure, and the fluid pressure source can be downsized. In addition, it is easy to reduce the weight and size of the grip including the fluid pressure cylinder. Further, since the wedge lifting fluid pressure cylinder functions as a damper, it is possible to absorb the breaking shock of the test piece and prevent the breaking torque from being applied to the initial tightening fluid pressure cylinder.

The present invention is not limited to the configuration shown in the above embodiment, and various changes can be made without departing from the scope described in the claims. Further, in the above embodiment, the case where the auxiliary gripping tool is held from the cross head by the pull rod has been described, but the present invention is not limited to this and can be applied to a shape built in the cross head. Further, the present invention can be applied not only to the vertical material testing machine but also to a horizontal material testing machine.

[0023]

As described above, according to the present invention, since the position of the wedge tooth for gripping the test piece in the load axis direction can be held constant, even if the cross-sectional size of the test piece changes, the wedge tooth can be held in this way. The grip position does not change,
The position of the wedge tooth with respect to the test piece is constant, and the length of the portion under test of the test piece can be constant. Moreover, it is possible to prevent a compressive load from being applied to the test piece during gripping. In addition, since the wedge teeth are supported by the fluid pressure cylinder that also serves as a damper, the initial tightening cylinder can be protected from the breaking shock of the test piece. Further, according to the present invention, by blocking the fluid pressure circuit of the initial tightening cylinder, the reaction force generated by the wedge action when the test piece is loaded can be supported only by the fluid pressure cylinder in the blocked state.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view showing an embodiment of a grip provided in a material testing machine of the present invention.

FIG. 2 is a front view showing a conventional gripping tool.

FIG. 3 is a front view showing a conventional gripping tool.

FIG. 4 is a front view showing a conventional gripping tool.

[Explanation of symbols]

 1 Upper gripping tool 2 Lower gripping tool 10 Gripping tool body 11,12 Wedge teeth 13,14 Initial tightening fluid pressure cylinder 15 Wedge lifting fluid pressure cylinder 16,17 Tapered guide member TP test piece

Claims (1)

[Claims] 1. A material testing machine comprising a gripping tool for gripping both ends of a test piece, wherein the gripping tool is symmetrical with a support member and an axis line orthogonal to the load axis line between the support member and the load axis line. A pair of initial tightening fluid pressure cylinders, a pair of guide members provided on the piston rod of each fluid pressure cylinder and having tapered surfaces that are symmetrically inclined in the load axis direction, and the tapered surfaces of these guide members. A pair of wedge teeth that slide along the shaft, and a fluid pressure cylinder that is attached to the support member and positions each wedge tooth in the load axis direction so as to allow movement in a direction orthogonal to the load axis. A material testing machine characterized by the above.