JPH1062324A - Material testing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely make the axis of a test piece coincide with a load axis without requiring labor. SOLUTION: Strain gauges 10A-10D are stuck to a dummy test piece TD, and a load is added to the dummy test piece TD to determine differential signals S1, S2 of the distortion signals outputted from the strain gauges situated on the diagonals by a differential equipment 11. XY drivers 13A, 13B drive motors 16A, 16B on the basis of the differential signals S1, S2 to drive an XY stage 9 so that the axis of the dummy test piece TD is made to coincide with the load axes of upper and lower grippers.

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 for loading a test piece by, for example, rotating a screw rod, and more particularly to a material testing machine capable of easily centering a test piece on a load shaft.

[0002]

2. Description of the Related Art Conventionally, there has been known a material testing machine in which both ends of a crosshead are screwed into a pair of screw rods erected on a table, and a pair of grippers are coaxially attached to the crosshead and the table. I have. In this material testing machine, after the both ends of the test piece are respectively gripped by the pair of grips,
The screw head is rotated to raise the crosshead relative to the table, thereby applying a tensile load to the test specimen.

[0003]

In such a tensile test, in order to improve the test accuracy, the test piece is gripped so that the axis of the test piece coincides with the center (load axis) of the upper and lower grips. Conventionally, the operator has performed centering work by intuition by directly visually observing the test piece. However, there is a problem that the visual centering work is troublesome and lacks accuracy. In particular,
For a material having high rigidity such as ceramics, there is a possibility that a test piece may be damaged by a bending load generated by slight eccentricity.

The object of the present invention is to
Further, it is an object of the present invention to provide a material testing machine capable of accurately aligning the axis of a test piece with a load axis.

[0005]

FIG. 1 shows an embodiment of the present invention.
3 will be described with reference to FIG.
The gripping tool 7 is applied to a material testing machine in which a test piece T having both ends fixed to both gripping tools is moved toward and away from the second gripping tool 8 in the axial direction of the load. Eccentricity detecting means 10A to 10D, 11 for detecting the eccentricity of the first and second gripping tools 7, 8 with respect to the load axes X1, X2;
And one of the second grippers 7 and 8 is moved two-dimensionally perpendicularly to the load axes X1 and X2, based on the detection results of the eccentricity detecting means 10A to 10D and 11. Movement control means 13A, 13 for moving the movement table 9 so that the axis of the test piece T and the load axes X1, X2 of the first and second grips 7, 8 coincide.
The above object is achieved by providing B, 16A and 16B.

Referring to FIG. 5, according to a second aspect of the present invention, the first grip 7 is separated from and connected to the second grip 8 in the load axis direction, and both ends are fixed to both grips. This is applied to a material testing machine that loads the test piece T, and both ends of the dummy test piece TD together with the second gripper 8 are set so that the axis of the test piece T and the axis of the dummy test piece TD match. A third gripper 18 to be fixed, and eccentricity detecting means 10A to 10D for detecting the eccentricity between the axis of the dummy test piece TD and the load axes of the first, second and third grippers 2, 8, 18; 11
A moving table 9 for moving one of the first and second gripping tools 7 and 8 two-dimensionally perpendicular to the load axis; and an eccentricity detecting means 1 while applying a load to the test piece T.
Based on the detection results of 0A to 10D, the dummy test piece TD
Axis, and first, second and third grips 7, 8, 18
The above object is achieved by providing the movement control means 13A, 13B, 16A and 16B for moving the movement table 9 so that the load axis coincides with the load axis.

The invention according to claim 3 further includes prohibiting means 14A, 14B, 15 and 17 for prohibiting the movement of the moving table 9 when the load on the test piece T exceeds a predetermined value.

According to the first aspect of the present invention, the eccentricity detecting means 1
The eccentricity between the axis of the test piece TD and the load axes of the first and second grips 7 and 8 is detected by 0A to 10D and 11;
Based on this detection result, the movement control means 13A, 13A
B, 16A and 16B move on the moving table 9, whereby the axis of the test piece TD coincides with the load axis of the first and second grips 7, 8. Then, the test piece TD
Is removed, and another test piece T having the same shape is fixed to the first and second grips 7 and 8 to perform the test, thereby performing the test without eccentricity between the load shaft and the test piece T. be able to.

According to the second aspect of the present invention, the eccentricity detecting means 1
The eccentricity between the axis of the dummy test piece TD and the load axes of the first, second and third grips 7, 8, and 18 is detected by 0A to 10D and 11, and based on the detection result, the movement control means. 13A, 13B, 16A and 16B are moving tables 9
Is moved, whereby the test piece T and the dummy test piece T
D axis and first, second and third grips 7, 8, 1
8 coincides with the load axis. Then, by performing the test in this state, the test piece T is loaded in a state where the axis of the test piece T and the load axes of the first and second grips 7 and 8 match.

When the load on the test piece T increases,
As the tensile load increases, the axis of the test piece T and the first and second axes
Alternatively, the eccentricity of the third grips 7, 8, and 18 with respect to the load shaft becomes negligibly small. Further, the moving table 9 becomes difficult to move, and if the moving table 9 is forcibly moved, the moving table 9 may be damaged.
According to the third aspect of the present invention, when the load on the test piece T exceeds a predetermined value, the movement of the moving table 9 is prohibited by the prohibiting means. The movement of the table 9 is prevented.

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.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION

-First Embodiment- Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration of a material testing machine according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line II of FIG.
FIG. 2 is a block diagram illustrating a configuration of a control device of the material testing machine according to the first embodiment.

FIG. 1 is a front partial sectional view of a material testing machine (tensile testing machine) according to the present invention. As shown in FIG. 1, in a tester main body 100, a pair of columns 1
, A lower end of the table 2 is supported at each end, and a cross yoke 3 is laid on the upper side. At both ends of the table 2, a pair of screw rods 4 (only one is shown) are erected inside each of the columns 1, and both ends of the crosshead 5 are screwed to these screw rods 4, respectively. Therefore, the crosshead 5 moves up and down with respect to the table 2 according to the rotation of the pair of screw rods 4.

On the lower surface of the crosshead 5, an upper grip 7 is provided via a load cell 6 and a universal joint 20.
However, a lower grip 8 is coaxially mounted on the upper surface of the table 2 via an XY table 9 described later, and both ends of the dummy test piece TD are gripped by these grips 7 and 8. As shown in FIG. 2, the dummy test piece TD has four strain gauges 10A to 10D on diagonal sections of the test piece TD.
Is affixed. As will be described later, this dummy test piece T
D is to be gripped when the centering of the upper and lower grips 7 and 8 is performed prior to the test, and is removed after the centering operation is completed, and a normal test piece T to which no gauge is attached is set. It is.

[0015] As shown in FIG.
0D is connected to the differentiator 11. In the differentiator 11, a difference signal S1 between the output of the strain gauge 10A and the output of the strain gauge 10C and a difference signal S2 between the output of the strain gauge 10B and the output of the strain gauge 10D are calculated.
The difference signals S1 and S2 are amplified by amplifiers 12A and 12B, respectively, and
3B. X driver 13A and Y
The driver 13B is connected to the X motor 16A and the Y motor 16B via the changeover switches 14A and 14B, respectively.
The stage 9 is moved in the X and Y directions in FIG.
Drive in a dimension. The changeover switches 14A, 14B
Electrically connects the X driver 13A and the Y driver 13B with the X motor 16A and the Y motor 16B only when switched to the position a.

The load cell 6 is connected to the comparator 15, and a load signal to the test piece T output from the load cell 6 is input to the comparator 15. Further, a load setting device 17 is connected to the comparator 15, and a setting signal indicating a load (for example, 20 kgf) set by the load setting device 17 is input to the comparator 15. The comparator 15 compares the setting signal input from the load setting device 17 with the load signal input from the load cell 6, and if the load signal is larger than the setting signal, sets the changeover switches 14A and 14B to b respectively.
Switch to position.

Next, the operation of this embodiment will be described. Prior to the tensile test, first, as shown in FIG. 2, a dummy test piece TD to which the strain gauges 10A to 10D are attached is gripped between the upper and lower grips 7, 8, and the screw rod 4 is rotated in a predetermined direction. As a result, the crosshead 5, that is, the upper grip 7 is raised, and a tensile load is applied to the dummy test piece TD. In this state, a strain signal corresponding to the strain of the dummy test piece TD is input to the differentiator 11 from the strain gauges 10A to 10D. In the differentiator 11, a difference signal S1 of the strain signal output from the strain gauges 10A and 10C on the diagonal and a difference signal S2 of the strain signal output from the strain gauges 10B and 10D are calculated.

If the load axis X1 of the upper grip 7 and the load axis X2 of the lower grip 8 are shifted from the axis O of the dummy test piece TD as shown in FIG.
Is subjected to a bending load in addition to a tensile load. Therefore,
Due to the bending load, a difference occurs in the strain signals detected by the strain gauges on the diagonal sides in the strain gauges 10A to 10D attached to the dummy test piece TD.
In the present embodiment, the difference signal S of the distortion signal
The XY stage 9 is moved so that the values of the differential signals S1 and S2 become 0 based on the dummy test pieces TD and TD.
And the load axes X1 and X2 are centered.

That is, the difference signals S1 and S2 calculated by the differentiator 11 are amplified by the amplifiers 12A and 12B, respectively, so that the X driver 13A and the Y driver 13
B is input. On the other hand, when a load equal to or more than the predetermined value is not applied to the dummy test piece TD, the changeover switch 14
Since A and B are switched to position a, X driver 13A and Y driver 13B output drive signals to X motor 16A and Y motor 16B, respectively. X
The motor 16A and the Y motor 16B
The XY stage 9 is moved two-dimensionally according to the drive signals input from the A and Y drivers 13B so that the difference signals S1 and S2 become 0. Thereby, centering of the axis O of the dummy test piece TD and the load axes X1 and X2 is performed.

On the other hand, when the load on the dummy test piece TD increases and exceeds the load set by the load setting unit 17, the comparator 15 switches the changeover switches 14A and 14B.
To the b position. Thus, even if the difference signals S1 and S2 are input from the differentiator 11 to the X driver 13A and the Y driver 13B, the drive signal is not input to the X motor 16A and the Y motor 16B, and therefore, the XY stage 9 does not move. It will be.

When the XY stage 9 cannot be moved when a tensile load exceeding the load set by the load setting device 17 is applied, the eccentricity is determined by the difference signal (the difference signal S).
1 (S2)) / (average value of all strain gauges). Therefore, the value of the eccentricity decreases as the tensile load increases and the strain of the dummy test piece TD increases, that is, the tensile load This is because the eccentricity becomes so small that it becomes negligible as the value becomes larger. Also, when the tensile load becomes large, it becomes difficult to move the XY stage 9.

Then, in this manner, the dummy test piece TD
, The dummy test piece TD is detached from the upper and lower grips 7 and 8, and the test piece T is gripped by the upper and lower grips 7 and 8 to obtain a test piece. By performing the tensile test of T, a bending load due to eccentricity does not act on the test piece T, and an accurate tensile test can be performed.

As described above, in the present embodiment, only the dummy test piece TD is gripped by the upper and lower grips 7 and 8 and a tensile load is applied, and the axis of the load axis X1 and the load axis X2 and the axis of the test piece T are changed. Because it can be centered with the heart O,
The center O of the test piece T can be accurately measured without any trouble.
Can be matched with the load axes X1 and X2, and an accurate tensile test can be performed. In this case as well, the eccentricity decreases as the applied load increases, and the movement of the XY stage 9 becomes difficult.
The centering work by the XY stage 9 is performed. Even if the universal joint 20 is omitted, the same operation and effect can be obtained.

-Second Embodiment- Next, a second embodiment of the present invention will be described.
FIG. 5 is a diagram showing a configuration of a material testing machine according to the second embodiment of the present invention. In FIG. 5, the same components as those in FIG. 1 are denoted by the same reference numerals, and detailed description will be omitted.
The second embodiment of the present invention includes an intermediate gripper 18 in addition to the upper gripper 7 and the lower gripper 8, and grips the test piece T with the upper gripper 7 and the intermediate gripper 18. The dummy test piece TD is formed by the gripper 18 and the lower gripper 8.
, And the above-described strain gauge 10 is attached to the dummy test piece TD.
The point that A to 10D are attached is different from the first embodiment. The intermediate grip 18 grips the dummy test piece TD and the test piece T so that the test piece T is centered.

Next, the operation of this embodiment will be described. First, as shown in FIG.
Is held between the intermediate gripper 18 and the lower gripper 8, the test piece T is gripped between the upper gripper 7 and the intermediate gripper 18, and the screw rod 4 is rotated in a predetermined direction. . As a result, the crosshead 5, that is, the upper grip 7 rises, and a tensile load acts on the test piece T and the dummy test piece TD. In this state, a strain signal corresponding to the strain of the dummy test piece TD is input to the differentiator 11 from the strain gauges 10A to 10D. Differentiator 1
In No. 1, the difference signal S1 of the strain signal output from the strain gauges 10A and 10C on the diagonal and the difference signal S2 of the strain signal output from the strain gauges 10B and 10D.
Is calculated.

Then, as in the first embodiment, the difference signals S1, S2 are determined based on the difference signals S1, S2.
The XY stage 9 is moved so that the value of 2 becomes 0, and the load axis X1 of the upper grip 7 and the load axis X2 of the lower grip 8 are moved.
And the axis of the dummy test piece TD are centered. By loading the test piece T while centering the axis of the dummy test piece TD and the load axes X1 and X2 in this way, the bending load does not act on the test piece T. A tensile test can be performed.

As described above, in the second embodiment, the intermediate grip 17 is used to hold the dummy test piece TD and the test piece T on the upper and lower grips 7 and 8 and the intermediate grip 1.
7, the center of the test piece T and the load axis X1 and the load axis X2 can be centered only by applying a tensile load. Axis X1, X of the upper and lower grips 7, 8
2 and an accurate tensile test can be performed.

In the first and second embodiments, the movement of the XY stage 9 is prohibited when a tensile load greater than the load set by the load setting device 17 is applied. It is not necessary to prohibit.

In the above embodiment, the lower grip 8 and the XY stage 9 are connected. However, the XY stage 9 is attached to the crosshead 5, and the upper grip 7 and the XY stage 9 are connected. May be. In this case, the lower grip 8 is attached to the table 2 via the load cell 6. Further, in the above embodiment, the material testing machine having the screw rod type load mechanism has been described, but the present invention can be applied to other various material testing machines.

In the correspondence between the above embodiment and the claims, the upper and lower grips 7 and 8 are the first and second grips, the strain gauges 10A to 10D and the differentiator 11 are the eccentricity detecting means, and the XY stage Reference numeral 9 denotes a movement table, the X motor 16A and the Y motor 16B constitute movement control means, and the changeover switches 14A and 14B, the comparator 15, and the load setting device 17 constitute inhibition means.

[0031]

As described above in detail, according to the first aspect of the present invention, the eccentricity between the load shafts of the first and second grips and the axis of the test piece is detected, and the detection result is obtained. The moving table is moved so that the axis of the test piece coincides with the load axes of the first and second gripping tools based on the above, so that it takes a lot of time only by gripping and loading the test piece. Thus, the axis of the test piece and the load axes of the first and second grips can be made to coincide with each other, whereby the test piece can be efficiently centered.

According to the second aspect of the present invention, the eccentricity between the dummy test piece and the load shafts of the first, second and third grips is detected, and the test piece and the dummy test piece are detected based on the detected results. The moving table is moved so that the axis of the shaft and the load axes of the first, second and third grips coincide with each other. , The axis of the test piece and the load axes of the first, second, and third grips can be made to coincide with each other, whereby the test piece can be efficiently centered.

According to the third aspect of the present invention, when the tensile load increases and the eccentricity between the axis of the test piece and the load axis of the first, second, or third gripping tool becomes negligibly small, the movement occurs. Because the movement of the table is prohibited,
When the eccentricity becomes so small as to be negligible, useless driving of the test machine can be prevented.

[Brief description of the drawings]

FIG. 1 is a front view showing an overall configuration of a material testing machine according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line II of FIG. 1;

FIG. 3 is a block diagram showing a control device of the material testing machine according to the first embodiment of the present invention.

FIG. 4 is a view showing a state in which the axis of the test piece and the load axis of the upper and lower grips are eccentric.

FIG. 5 is a front view showing the overall configuration of a material testing machine according to a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 support 2 table 4 screw rod 5 cross head 6 load cell 7 upper grip 8 lower grip 9 XY stage 10A to 10D strain gauge 11 differentiator 15 comparator 16A X motor 16B Y motor 17 load setting device 18 intermediate grip

Claims (3)

[Claims] 1. A material testing machine in which a first gripper is separated from and brought into contact with a second gripper in a load axis direction and a test piece having both ends fixed to both grippers is loaded. An eccentricity detecting means for detecting an eccentricity between an axis and a load axis of the first and second grips; and providing one of the first and second grips perpendicularly to the load axis by two A moving table that moves in a three-dimensional manner, and based on a detection result of the eccentricity detecting means, moves the moving table so that an axis of the test piece and a load axis of the first and second gripping tools coincide. A material testing machine, comprising: 2. A material testing machine in which a first gripper is separated from and brought into contact with a second gripper in a load axis direction, and a test piece having both ends fixed to both grippers is loaded. A third gripper for fixing both ends of the dummy test piece together with the gripper so that the axis of the test piece and the axis of the dummy test piece coincide with each other; Eccentricity detecting means for detecting eccentricity of the second and third grips with the load axis, and one of the first and second grips is two-dimensionally perpendicular to the load axis. A moving table to be moved, and an axis of the dummy test piece and a load axis of the first, second, and third grips, based on a detection result of the eccentricity detection means while applying a load to the test piece. Moving control means for moving the moving table so as to match; Materials testing machine characterized by comprising. 3. The material testing machine according to claim 1, further comprising a prohibition unit for prohibiting the movement of the moving table when a load on the test piece becomes a predetermined value or more. .