JPH04295743A - Test-piece aligning apparatus - Google Patents

Abstract

PURPOSE:To make it possible to perform aligning work accurately in a short time by making it possible to adjust the interval between guide members under the state wherein a pair of the guide members keep the relationship of axial symmetry with respect to a loading axis, holding a test piece with the guide members, and determining the position. CONSTITUTION:The interval between a pair of guide members 25a and 25b is adjusted with adjusting means 24A, 24B and 26 according to the width of a test piece TP. A main body 22 is driven to a position wherein the members 25a and 25b are inserted between test jigs 5 and 6 with a driving means 21. Under this state, the position of the test piece is determined so that the test piece is held between the members 25a and 25b. The test piece is held with the holding jigs 5 and 6. The interval between the guide members 25a and 25b is adjusted under the state wherein the relationship of the axial symmetry with respect to a loading axis 1 is kept. Therefore, the test piece can be aligned simply and accurately.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a test piece positioning device for aligning the center of a test piece with the center of a grip (load axis).

0002

[Prior art and its problems] A displacement meter that grips a test piece and applies a tensile load to a pair of test jigs arranged coaxially with the load axis, and tracks a pair of gauge marks provided on the test piece. A conventional test method has been used to measure the amount of elongation of a test piece. During such tests, the specimen gradually becomes thinner as it stretches, so if the center of the specimen is not aligned with the load axis, that is, if it is not centered, the specimen may deviate from the load axis. As a result, the displacement meter described above may not be able to track the marked line, making it impossible to measure the elongation. In particular, in the case of a soft test piece with a large amount of elongation, the test piece becomes quite thin due to the tensile load, so it is easy to deviate from the load axis and the above problem is likely to occur. However, in the past, there was no device for centering the test piece, so the operator used intuition to align the center of the test piece with the load axis and grip it with the grip, which took time. In addition, there is a problem that accurate centering cannot be performed.

[0003] An object of the present invention is to provide a test piece positioning device that can perform the above-mentioned centering work in a short time and accurately.

0004

[Means for Solving the Problems] To explain with reference to FIG. 1 showing one embodiment, the present invention provides a pair of test jigs 5 and 6 (FIG. 2) disposed coaxially with a load axis L. It is applied to a test piece positioning device used in a material testing machine that grips the piece TP and applies a load. Then, the positioning device main body 22
A pair of guide members 25a and 25b are provided on this main body 22 so as to be able to move toward and away from the load axis L, and sandwich the test piece TP in the width direction, and these pair of guide members 2
Adjusting means 24A, 24B, 26 for adjusting the interval between the guide members 25a, 25b with the guide members 5a, 25b maintaining a line-symmetric relationship with respect to the load axis L; and a pair of guide members 25.
The main body 22 is located between the position where a and 25b are inserted between the pair of test jigs 5 and 6 and the position where they are withdrawn from between the test jigs 5 and 6.
The above-mentioned problem is solved by this.

[0005]

[Operation] The adjusting means 24A, 24B, 26 adjust the distance between the pair of guide members 25a, 25b according to the width of the test piece TP, and the driving means 21 moves the main body 22.
A pair of guide members 25a and 25b are driven to a position where they are inserted between test jigs 5 and 6. In this state, the test piece is positioned so as to be sandwiched between the pair of guide members and gripped by the grips 5 and 6. Since the distance between the guide members 25a and 25b is adjusted while maintaining a line-symmetric relationship with respect to the load axis L, the test piece can be easily and accurately centered by the above operation.

[0006] In the section of means and effects for solving the above-mentioned problems that explains the structure of the present invention, figures of embodiments are used to make the present invention easier to understand. It is not limited to.

[0007]

[Embodiment] An embodiment of the present invention will be explained with reference to FIGS. 1 to 5. FIG. 2 is a front view of a material testing machine equipped with a test piece positioning device according to the present invention. A yoke 3 is horizontally suspended on the upper part of a pair of pillars 2 erected on a table 1, and a crosshead 4 is supported on the lower part thereof so as to be movable up and down. An upper grip 5 and a lower grip 6 are attached to the lower surface of the yoke 3 and the upper surface of the crosshead 4, respectively, so as to face each other. Each is grasped. Here, as shown in FIG. 3, the grip teeth 5a, 6a are arranged coaxially with the load axis L.

A test piece positioning device 20 for positioning the test piece TP is attached to one of the pillars 2. Figure 1
2 is a perspective view showing details of this positioning device 20.
Reference numeral 1 denotes an air cylinder fixed to the support column 2, and 22 a main body connected to the tips of a pair of rods 21a of the air cylinder 21 via a bracket 23. The main body 22 is
Due to the expansion and contraction of the air cylinder 21, the positioning guides 25a and 25b, which will be described later, are located between an advanced position where they are located between a pair of grips 5 and 6, and a retracted position where the positioning guides 25a and 25b are retracted from between the grips 5 and 6. It is said to be movable.

Inside the main body 22, a pair of plate members 24A are provided.
, 24B are inserted so as to be separable from the load shaft L,
As shown in FIG. 4, the plate member 24A has a nut 24a with a right-hand female thread, and the plate member 24B has a left-hand female thread 24b.
Nuts 24b each having a shape formed thereon are fitted in a non-rotatable manner. Further, two positioning guides 25a, 25b are provided on the front surface of each of the plate members 24A, 24B, and the test piece is held between these positioning guides 25a, 25b.

26 is a nut 24a of the plate member 24A.
The rotating shaft 26 has a right-hand male threaded portion 26a that is screwed into the nut 24b of the plate member 24B, and a left-hand male threaded portion 26b that is screwed into the nut 24b of the plate member 24B.
, 22b rotatably but immovably in the axial direction. Further, an operating section 26c is formed at one end of the rotating shaft 26, and when the rotating shaft 26 is rotated by this operating section 26c, the pair of plate members 24A, 24B are arranged in a line-symmetrical relationship with respect to the load axis L. The positioning guides 25a and 25b are thereby moved while maintaining the same relationship (in the direction of the arrow in FIG. 1).

FIG. 5 also shows a displacement meter 50 for detecting the amount of elongation of the test piece TP. This displacement meter 50 has a pair of upper and lower clip-type detection heads 52U, 52L protruding from the displacement meter main body 51, and each head 52U, 52L has a
It is possible to move back and forth from the illustrated position to the position of the load axis L, and the upper and lower marked line positions PL provided on the test piece TP
, PU (Fig. 3) are attached so as to sandwich the test piece TP in the thickness direction. Detection head 52U, 52L
can be lowered from the position shown by the solid line to the position shown by the two-dot chain line according to the elongation of the test piece TP, and the detection head 52U
, 52L distance change X (=X1-X0) is the test piece T
It is output as the amount of elongation of P.

Next, the operation of the embodiment will be explained. Test piece T
When installing P on the testing machine, first the positioning device 20
With the main body 22 in the retracted position, the distance between the positioning guides 25a and 25b is adjusted to match the width of the test piece TP. That is, the test piece TP is placed between the positioning guides 25a and 25b with the above-mentioned interval being larger than the width of the test piece TP.
After insertion, the rotating shaft 26 is rotated by the operating portion 26c, and the plate members 24A, 24B are driven toward each other until the positioning guides 25a, 25b are in a state where the test piece TP is held in the width direction.

After that, the test piece TP is removed, and the air cylinder 21 is extended to drive the main body 22 to the advanced position.
The positioning guides 25A and 25B are positioned between the upper and lower grips 5 and 6. Then, with the upper and lower gripping teeth 5a, 6a open, the test piece TP is placed on each guide 25 as shown in FIG.
a, 25b, and the test piece TP is positioned such that the upper and lower parts thereof can be gripped by the gripping teeth 5a, 6a, and then the gripping teeth 5a, 6a are closed and gripped. At this time, the positioning guides 24A and 24B maintain a line-symmetrical relationship with respect to the load axis L, and the distance between them is the same as that of the test piece TP.
Since the test piece TP is adjusted according to the width of the gripper, the test piece TP is gripped with its center aligned with the center of the gripping teeth 5a, 6a, that is, centered with respect to the grippers 5, 6.

Thereafter, the air cylinder 21 is contracted to retract the main body 22 to a position where the positioning guides 25a and 25b are retracted from between the grips 5 and 6, and the above-mentioned positions PU and PL of the test piece TP are moved to the upper and lower marked line positions PU and PL. The detection heads 52U and 52L of the displacement meter 50 are respectively attached, and in this state, the crosshead 4, that is, the lower grip 6 is lowered to apply a tensile load to the test piece TP. As a result, the test piece TP
extends, and in accordance with the extension, the detection heads 52U, 52L follow the reference points PU, PL and descend.

At this time, the test piece TP gradually becomes thinner as it stretches, so if the test piece TP is not centered, the test piece TP may deviate from the load axis L, for example, to the right in FIG. In this case, the detection heads 52U and 52L, which can only move up to the load axis L, come off the test piece TP, making it impossible to detect the amount of elongation. According to this embodiment, the test piece TP is centered with respect to the grips 5 and 6 by the above operation, so even if the test piece TP becomes quite thin, it will not come off the load axis L, and the detection head 52U and 52L can be prevented from coming off the test piece TP. Therefore, the amount of elongation can be reliably detected even in a soft test piece with a large amount of elongation.

[0016] Also, during the test, the positioning guide 25
Since the guides a and 25b are retracted from between the grips 5 and 6, they do not interfere with the installation of the displacement meter, and the guides 25a and 25b abut against the test piece TP during the test, thereby preventing eccentric loads from acting on it. Accurate test results can be obtained without any problems.

In the configuration of the above embodiment, the upper and lower grips 5 and 6 hold the pair of testing machine jigs on the positioning guide 25a.
, 25b connect the pair of guide members to the plate members 24A, 24B.
The rotating shaft 26 constitutes an adjusting means, and the air cylinder 21 constitutes a driving means.

In the above description, the distance between the positioning guides 25a and 25b is adjusted with the main body 22 in the retracted position, but this adjustment work may also be performed in the extended position. In addition, the positioning guide 25 is equipped with a screw mechanism.
a, 25b, but the positioning guide 2
As long as 5a and 25b move while maintaining a linearly symmetrical relationship with respect to the load axis L, any driving method may be used. Alternatively, an actuator such as a motor may be provided to adjust the distance between the positioning guides 25a and 25b. Further, the shape and number of the positioning guides 25a and 25b are not limited to those in the embodiment, and the positioning guides may be configured by, for example, a plate-shaped member extending in the vertical direction.

Furthermore, the gauge line of the test piece is set to the load axis L.
Even when using a type of displacement meter that optically detects the amount of elongation by following its movement, the same problem as described above will occur if the test piece deviates from the load axis L. The invention can be applied in the same way. Furthermore, the driving means is not limited to the air cylinder 21, and the configurations of the grips 5 and 6 are not limited to the embodiments. Furthermore, it can be applied to a type of testing machine that applies a tensile load to the test piece by driving the upper grip 5.

[0020]

According to the present invention, the interval between the pair of guide members can be adjusted while maintaining a line-symmetrical relationship with respect to the load axis, and the test piece can be positioned by being held between the guide members. This makes it possible to center the test piece in a short time and more accurately.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a test piece positioning device according to an embodiment of the present invention.

FIG. 2 is a front view of a material testing machine equipped with the positioning device.

FIG. 3 is a diagram illustrating a centering operation of a test piece.

FIG. 4 is a plan sectional view showing a part of the positioning device.

FIG. 5 is a side view showing an example of a displacement meter.

[Explanation of symbols]

5 Upper grip 5a Grasp teeth 6 Lower grip 6a Grasp teeth 20 Test piece positioning device 21 Air cylinder 22 Main body 24A, 24B Plate member 24a, 24b Nut 25a, 25b Positioning guide 50 Displacement meter PU, PL Marked line position TP test piece

Claims (1)

[Claims] Claim 1: A test piece positioning device used in a material testing machine that grips a test piece and applies a load to a pair of test jigs disposed coaxially with a load axis, comprising: a positioning device main body; a pair of guide members that are provided so as to be separable from each other with respect to the load axis and sandwich the test piece in the width direction; and a state in which these pair of guide members maintain a line-symmetrical relationship with respect to the load axis. an adjusting means for adjusting the interval between the guide members; and a driving means for driving the main body between a position where the pair of guide members is inserted between the pair of test jigs and a position where the guide members are retracted from between the test jigs. A test piece positioning device comprising: