JP2001228067A - Material tester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically change the height of a thermostatic camber, according to the amount of shape alteration of a test piece. SOLUTION: This material tester is provided with the thermostatic chamber 11, to hold a test piece 9 at a constant temperature. One end of a bellow 15 is jointed to the upper-part opening of the thermostatic chamber 11, and the other end is sealed to a member on the side of cross had 5, a bellow-suspending plate 14. Therefore, it is possible to automatically extend the bellow 15 according to the extension of the test piece 9 which occurs, when the cross head 5 is elevated, to perform tensile tests without exertion of the extending and contracting forces of the bellow 15 on a load cell 6, and to secure large strokes for material tests through the use of a compact thermostatic chamber.

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 constant temperature bath for performing a material test while changing temperature conditions.

[0002]

2. Description of the Related Art A material testing machine is used to evaluate the mechanical strength of a solid material, whether metallic or non-metallic. In the material test, a test piece molded in a certain shape is fixed to a pair of grips and held between the table and the crosshead, and tensile or compressive stress is applied to the test piece, and the amount of strain generated in the test piece at that time Is to measure and evaluate the mechanical properties of the material by obtaining a stress-strain curve.However, the mechanical properties of rubber and high-molecular substances depend on the degree of polymerization, molecular weight, additives, heat treatment, etc. Since the temperature changes greatly and its temperature coefficient is large, it is desirable to conduct the test under constant temperature conditions.Therefore, a material testing machine equipped with a constant temperature bath and capable of setting the test temperature to various levels has been developed and has already been put into practical use. ing.

[0003]

When the sample to be tested is a rubber or a high-molecular substance, the amount of deformation is relatively large with respect to stress, and a large elongation of 400% or more of the original length may be exhibited. In order to perform a practical test on such a test piece, the thermostatic chamber must have a sufficient volume to keep the test piece and the pair of grips to which the test piece is fixed at uniform temperature conditions. Would require a constant temperature bath with a considerable height in the direction of tension. However, in a general-purpose material testing machine, when the height in the thermostatic chamber is increased, it is necessary to increase the stroke by about twice the increase, which leads to an increase in the size of the material testing machine. On the other hand, the deformation amount of all test objects is not always large.For example, even in the case of rubber or polymer material, the deformation amount is small when measured in a low temperature range, and the deformation amount is relatively small like an inorganic material. In some cases, small materials are used. In such a case, if a thermostat with a large height is used, wasted energy will be wasted to heat and cool the entire interior, and the equipment will also be large. There was a point. As described above, when designing a general-purpose material testing machine which is easy to use and excellent in economical efficiency, a certain limitation caused by the structure of the constant temperature bath is always a problem.
That is, a constant temperature bath can heat up to several hundred degrees Celsius in a high temperature range, and in a negative temperature range, it must cover a wide temperature range up to about -180 ° C. by using a refrigerator or a low temperature gas such as liquid nitrogen gas. However, energy consumption tends to be large, and it is desirable to reduce the size of the thermostat as much as possible. There are many times.

In view of the above-described problems, the present invention is similar to that in which the height of the thermostatic chamber is automatically changed apparently in accordance with the amount of deformation of the test piece, and the height of the thermostatic chamber is extended. It is an object of the present invention to provide an easy-to-use material testing machine which is devised so as to obtain an effect and which can reduce the size of the apparatus and reduce energy consumption.

[0005]

In order to achieve the above object, a material testing machine according to the present invention comprises a thermostat for keeping a temperature of a test piece constant, and an opening through which a rod penetrates the thermostat. A partition wall is provided between the member on the side of the crosshead and the partition wall so as to surround the rod and expand and contract in the longitudinal direction of the rod. Therefore, the partition can be automatically expanded and contracted in accordance with the deformation of the test piece, a large stroke can be taken for the material test under a constant temperature condition, and a load for expanding and contracting the partition is not applied to the load cell.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a general view of a material testing machine 1 according to the present invention, in which a pair of columns 3 erected on a table 2 is fixed by a horizontal support 4 at the upper part. A threaded rod (not shown) which is driven to rotate by a motor (not shown) is provided inside the column 3. Both ends of the crosshead 5 are screwed to this screw bar, and the crosshead 5 can be moved up and down by rotation of the screw bar. The lower grip 10 is mounted on the table 2 through its bottom in a thermostat 11, while the upper grip 8 is connected to the thermostat 11 from the crosshead 5 via a load cell 6 and a rod 7. It is suspended inside. That is, an opening through which the rod 7 penetrates is formed above the thermostatic bath 11, and the rod 7 is provided through the opening. The test piece 9 is gripped by the grippers 8 and 10.

The test piece 9 is stretched by being pulled by the ascending movement of the crosshead 5, and the movable range of the gripper 8 indicates the magnitude of the stroke. One end of a bellows 15 is fixed to a bellows suspending plate 14 fixed to a bellows hanging bar 12 hung from the crosshead 5, and the other end is fixed to an opening above the thermostat 11. The load cell 6 is shielded from the heat of the thermostatic chamber 11 by a heat shield plate 13 mounted on a bellows hanging rod 12. FIG. 2A shows a state in which the rod 7 is lowered, and the bellows 15 is folded into an opening above the thermostat 11. In this state, the test piece 9 is gripped by the gripper 8 and the gripper 10 at room temperature. FIG. 2B shows a state in which the test piece 9 is extended by rotating the screw rod to raise the crosshead 5, and the bellows 15 is pulled up.

Next, the operation of the above configuration will be described. FIG. 1 shows an overview of a material testing machine according to the present invention, which will be described in detail with reference to FIG. FIG. 2A shows the relationship between the respective parts when the cross head 5 is lowered. The bellows 15 made of cloth impregnated with a resin bellows or a heat-resistant resin is provided with an elastic bellows 15 inside the thermostat 11. One end is sealed and fixed to the bellows suspending plate 14 and the other end is sealed and fixed inside the opening at the upper part of the thermostatic chamber 11 so that the airtightness is maintained even if the mixture is stirred by the fan at high speed. Therefore, only a small amount of air leaks from the gap between the pulling device 7 and the bellows suspension plate. Since the thermostat 11 is fixed to the material testing machine 1, the lowering of the crosshead 5 causes the bellows suspension plate 1 to move.
The bellows 15 is pressed as the 4 moves in conjunction with it, and is folded over the thermostat 11.

In this state, the test piece 9 having a length L0 is gripped by the gripper 8 and the gripper 10, the door of the thermostatic chamber 11 is closed, and the temperature control operation is performed. After confirming that the temperature of the thermostat 11 is stable, the zero point of the load cell 11 is reset, and the screw head 3 of the material testing machine 1 is driven and rotated by a motor to raise the crosshead 5 to pull the material. At this time, the moving distance (that is, the amount of distortion) of the crosshead 5 and the load cell 6
By recording the output (ie, stress) relationship of
The tensile test of the test piece 9 at that temperature can be performed.

FIG. 2B shows a test piece 9 having a length L0 at the start of measurement, which has been extended to a length L by a tensile test. As is clear from the drawing, the gripper 8 is a thermostat. 11 is located outside. Conventionally, when measuring a sample exhibiting such a large elongation, the height of the thermostat 11 is extended and the stroke of the material testing machine is extended, but this method is used as described above. It is necessary to increase the stroke about twice as much as the height of the thermostat 11 and the apparatus becomes large. However, according to the present invention, the bellows 15 fixed to the bellows suspending plate 14 is pulled up in conjunction with the elevation of the crosshead 5, and the bellows 15 acts as a partition wall for isolating the inside of the thermostat 11 from the outside air. Since the inside is sufficiently stirred, the temperature of the test piece 9 is kept almost at the set temperature, and the same effect is obtained as the height of the thermostat 11 is automatically extended in conjunction with the extension of the test piece 9. It is done.

As is apparent from FIG. 2, the load cell 6 is directly connected to the crosshead 5 and is independent of the system for moving the bellows 15 up and down. I will not do it. The heat shield plate 13 has an effect of blocking the radiant heat from the thermostat and the effect of heat conduction from the rod 7, and the heat shield plate 13 substantially reduces the thermal influence of the load cell 6 from the thermostat 11. Can be erased.

According to the present invention, the internal volume of the thermostat 11 automatically changes in conjunction with the elongation of the test piece 9, so that energy for heating or cooling the thermostat 11 is saved, and the cost is reduced. Leads to driving.

Since the bellows 15 is folded at the upper opening of the thermostat 11, the stroke can be increased substantially by the thickness when the bellows shrinks. However, when the bellows 15 is small, the opening is reduced. Alternatively, it may be mounted on the upper part of the thermostat 11 and fixed.

The shape of the bellows 15 is not limited to the lantern structure shown in the drawing, but may be any shape as long as it surrounds the rod 7 and acts as a partition wall for isolating the inside of the thermostat 11 from the outside air. It may be of a structure in which containers stacked and molded in multiple layers are sequentially drawn or layered, or bellows. Further, the upper end of the bellows 15 may be directly surface-bonded to the lower surface of the crosshead 5.

[0015]

Since the present invention is configured as described above, the height of the thermostat is automatically extended in accordance with the extension of the sample piece, so that the apparatus can be reduced in size and energy saving operation can be performed.

[Brief description of the drawings]

FIG. 1 is a view showing an overview of a material testing apparatus of the present invention.

FIG. 2 (A) shows the relationship of each part when the tensioning device is lowered, and FIG. 2 (B) shows the relationship of each part when the test piece extends beyond the height of the thermostat in a tensile test.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Material testing machine 2 ... Table 5 ... Crosshead 6 ... Load cell 7 ... Rod 8 ... Gripping tool 9 ... Test piece 10 ... Gripping tool 11 ... Constant temperature bath 14 ... Standing bellows 15 ... Standing

Claims (1)

[Claims] A test specimen is gripped between a gripper on a table side and a gripper held at one end of a rod installed on a crosshead via a load cell, and a load is applied to the test specimen by moving the crosshead. In the material testing machine for providing and testing, a thermostat is provided for accommodating the test piece and keeping the temperature of the test piece constant, and between the opening through which the rod penetrates the thermostat and the member on the crosshead side. A material testing machine, further comprising a partition wall surrounding the rod and extending and contracting in the longitudinal direction of the rod.