JP2002195804A - Strain gauge type displacement gauge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a strain gauge type displacement gauge capable of precisely measuring the displacement of a test piece without having any excessive change of a strain gauge even in the increase in nipping angle of both arms by the extension of the test piece. SOLUTION: This displacement gauge comprises two arms 1A and 1B rotatably connected to each other on their base end sides and engagingly locked to the test piece 3 on their tip sides; a plate spring member 7 extensionally provided on one arm 1A of the two arms 1A and 1B; a rope 10 having one end connected to the tip of the plate spring member 7 and the other end connected to the other arm 1B of the two arms 1A and 1B and having a tensile spring 9 interposed in the middle; and a strain gauge 8 stuck to the plate spring member 7 and changed in electric resistance according to the curving degree of the plate spring member 7. Accordingly, when the test piece 3 is extended, the tensile spring 9 is also extended to minimize the deformation of the strain gauge 8, and the displacement quantity by the extension of the test piece 3 can be precisely measured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strain gauge type displacement meter for measuring the displacement of a test piece or the like in a material testing machine using a strain gauge.

[0002]

2. Description of the Related Art As shown in FIGS. 3 and 4, a conventional strain gauge type displacement meter which uses a test piece of a material testing machine as a displacement body and measures the amount of displacement thereof has a tip end locked to a test piece TP. And a pair of arms A1 and A2
1. Two leaf springs B1, B2 attached to the base end side of A1, A2 and mounted orthogonal to each other;
1, and a strain gauge G attached to one of B2, B2.

[0003] In this case, a clamping mechanism is provided on the distal end side of both arms A1 and A2 so as to be locked to and maintain the test piece TP and separate from the arms A1 and A2. As shown in FIG. 4, the arm A2 has a knife edge NB at the tip thereof for locking to the test piece TP and a locking frame K extending to both sides at the tip, while holding the arm A2 separately from the arm A2. The holder H is opposed to the holder H.
As is apparent from the above, an enclosing frame R is extended from both ends of the locking frame K via a knife edge NK. The test piece TP is held between the locking frame K and the surrounding frame R.

[0004] In addition, the holder H is provided with an urging mechanism for urging the knife edge NB to the test piece TP via the surrounding frame R. That is, a cylinder C is projected from the retainer H, and a spool P urged rightward by a compression spring S housed at the left end penetrates the cylinder C. The right end of the spool P protrudes toward the surrounding frame R, and a locking piece F that is locked to the test piece TP is attached to the tip of the spool P. Therefore,
When the elasticity of the compression spring S presses the test piece TP via the locking piece F, the locking frame K is urged leftward by the surrounding frame R, and as a result, the test piece TP is It will be sandwiched between the NB and the locking piece F. With such a holding mechanism, the distal ends of the two arms A1 and A2 are firmly locked at the respective reference points of the test piece TP.

[0005] In this manner, the base ends of the arms A1 and A2 whose distal ends are locked to the test piece TP are configured to be swingable about one point. That is, as shown in FIG. 3, L-shaped support frames L1 and L2 facing each other are formed in parallel at the base ends of both arms A1 and A2, and leaf springs B1 and B2 are provided at the ends of the respective support frames. They are supported so as to cross each other in a cross shape. One arm A2
Is provided with a cover frame D, and the cover frame D is configured to receive the base ends of the arms A1 and A2. Although both leaf springs B1 and B2 are formed of separate members, they are cross-shaped and both ends are connected to the base ends of separate arms A1 and A2, respectively. Is a center point, and both arms A1 and A2 swing about this center point. Therefore, when the test piece TP is extended and displaced, the arms A1 and A2 swing in the wide angle direction around the center point.

In the above configuration, a strain gauge G is attached to the leaf spring B1. As described above, the strain gauge G has a degree of curvature (degree of bending) of the attached leaf spring B1.
When the wide angle of both arms A1 and A2 is displaced by the elongation change of the test piece TP, the electric resistance is changed according to the amount of displacement. It becomes. The strain gauge G is normally configured as a resistor on one side of the bridge circuit, and outputs a signal corresponding to the displacement amount to a display (meter) (not shown) via the lead wire W.

[0007]

With the conventional strain gauge type displacement meter described above, the measurement accuracy is good when the displacement of the test piece TP is small, but the displacement is large. If the degree of curvature of the spring B1 increases and the strain amount of the strain gauge becomes excessive, the proportional relationship between the displacement amount and the electric resistance value is broken. Therefore, when the degree of curvature of the strain gauge G is within a certain range, for example, when the amount of displacement is large, it is necessary to use the arms A1 and A2 with a large length. However, when the lengths of the arms A1 and A2 are increased, the strain gauge type displacement meter becomes large and heavy. The large weight has a problem that the locking to the test piece, that is, the setting and removal operations are complicated and difficult, and the measurement accuracy is reduced. An object of the present invention is to provide a strain gauge type displacement meter which solves such a problem.

[0008]

In order to solve the above-mentioned problems, a strain gauge type displacement meter provided by the present invention has a plate-like spring body extended to one of two arms and one end thereof. A cable rod body connected to the distal end of the plate-shaped spring body and the other end connected to the other arm of the two arms, and a tension spring interposed in the middle; And a strain gauge whose electric resistance value changes in accordance with the degree of curvature of the plate-shaped spring body. Therefore, even though both arms are displaced by the displacement amount of the displacement body such as the test piece, the displacement of this arm is not directly transmitted to the bending of the strain gauge, but is transmitted by being reduced by the tension spring, and the strain is distorted. The amount of strain in the gauge does not become excessive.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A strain gauge type displacement meter provided by the present invention will be described below with reference to FIG. FIG. 1 is a view showing a strain gauge type displacement meter according to the present invention from the side.
Are arms that can swing about the support shaft 2, and each end has a knife edge 4 </ b> A, 4 </ b> B locked to the test piece 3.
Is fixed. 5A and 5B are knife edges 4A and 4
B, a gripper for supporting the strain gauge type displacement meter on the test piece 3 in cooperation with B, that is, a roller. The rollers 5A and 5B and the knife edges 4A and 4B are the same as those in FIG. It is configured as a part of a support mechanism 6 for supporting the displacement meter on the test piece 3.

In the above-described configuration, in the strain gauge type displacement meter of the present invention, the distal end of one arm 1A is formed in an L-shape, and the plate-like spring material 7 extends on the L-shaped portion 1L. It is established. And the plate-like spring material 7
The strain gauge 8 is stuck on. Further, a cable body 10 having a coiled tension spring 9 interposed therebetween is continuous with the tip of the plate-shaped spring material 7.
Is connected to a pin 11 implanted in a hole HB drilled in the middle of the other arm 1B through the hole HA of the arm 1A. The spring constant of the tension spring 9 is set small. In FIG. 1, a lead wire for deriving an output signal of the strain gauge 8 is not shown, but the signal is output from the strain gauge 8 via the lead wire as in the related art. Reference numeral 12 denotes a hook for connecting the cable body 10 to the plate-like spring body 7.

Since the strain gauge type displacement meter provided by the present invention is configured as described above, when the test piece 3 is extended and displaced by a load, the included angle between both arms 1A and 1B is enlarged accordingly. At this time, the plate-shaped spring member 7 is bent and displaced via the cord body 10 by the enlarged displacement. Due to the deformation of the plate-like spring member 7, a signal corresponding to the amount of extension of the test piece 3 is output from the strain gauge 8. In this case, the tension spring 9 is interposed in the cable body 10, and the tension spring 9 also extends although the spring constant is set small, and as a result, the deformation of the plate-like spring material 7 is reduced.

In this way, the bending deformation of the strain gauge becomes small and proportional to the amount of extension displacement of the test piece 3 so that excessive deformation does not occur. Therefore, it is possible to accurately measure even a considerably large amount of extension displacement of the test piece 3. FIG. 2 is a view showing a modification of the present invention, and is an embodiment which is particularly effective for testing a material having a large (long) extensional displacement. The difference from the embodiment of FIG. 1 is that the cord body 13 is long and the tension spring 14 can be set long at the same time, and the L frame 1L extended to the arm 1A.
An extension frame 1T is integrally extended. Then, a plate-like spring material 15 is fixedly provided at the end of the extension frame 1T, and the strain gauge 8 is attached to the plate-like spring material 15.

One end of the cable body 13 is connected to a pin 16 provided at the tip of a plate-like spring material 15, and the other end is connected to a roller 17.
Through holes HA, HB drilled in both arms 1A, 1B
And is connected to the pin 11 installed in the hole HB of the arm 1B. In this case, the tension spring 14 is interposed at a long length from the pin 16 to the roller 17 so that the tension spring 14 can be deformed in accordance with the extension of the long cord 13. In the case of the embodiment shown in FIG. 2, the cord body 13 is longer than the cord body 10 shown in FIG. It will be able to respond to displacement.

In this embodiment, the knife edge 4A
When the roller 17 is disposed on a straight line connecting the tip of the shaft 2 and the center of the spindle 2, the distance between the knife edges 4A and 4B and the pin 11
The measurement accuracy can be improved because the distance between the roller 17 and the roller 17 is proportional.

As described in detail above, the strain gauge type displacement meter provided by the present invention does not directly transmit the angular displacement between the two arms as the curved deformation of the strain gauge, but involves the extension of the tension spring. It is characterized in that the strain gauge is transmitted to reduce the deformation of the strain gauge. Embodiments utilizing such features are not limited to the illustrated examples, but may include various modifications.

For example, there can be mentioned an embodiment in which the lengths of both arms can be freely adjusted, and the length of the cord can be adjusted in accordance with the adjustment. In this embodiment, the displacement (elongation) measurement suitable for the material can be performed by adjusting the type and size of the test piece (types having different amounts of elongation). Further, as a modification of the embodiment of FIG. 2, the arrangement of the roller 17 can be provided at the position of the hole HA of the arm 1A to simplify the structure. Further, the present invention is applicable not only to the measurement of the displacement of a test piece but also to the measurement of the displacement of many other displacement bodies. The present invention covers all these variations.

[0017]

The strain gauge type displacement meter provided by the present invention is as described in detail above. For example, even when the displacement of the test piece is large, the deformation of the strain gauge can be minimized. As a result, highly accurate displacement measurement can be guaranteed over the entire range from a small displacement to a large displacement. In addition, it is possible to provide a displacement meter that can reduce the length of the arm, simplify the structure, reduce costs, reduce the number of failures, increase the durability, and have excellent operability and economy.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a strain gauge type displacement meter according to the present invention.

FIG. 2 is a diagram showing a second embodiment of the strain gauge type displacement meter according to the present invention.

FIG. 3 is a diagram showing a conventional strain gauge type displacement meter from the side.

FIG. 4 is a diagram showing a conventional strain gauge type displacement meter as viewed from the top of a plane crossing a test piece.

[Explanation of symbols]

 1A, 1B ... Arm 2 ... Spindle 3 ... Test piece 4A, 4B ... Knife edge 5A, 5B ... Roller 6 ... Nipping tool 7, 15 ... Flat spring material 8 ... Strain gauge 9, 14 ... Tension spring 10, 13 ... Cord body 11, 16 ... Pin 12 ... Hook

Claims (1)

[Claims] 1. Two arms whose respective base ends are rotatably coupled and whose distal ends are respectively locked by displacement bodies.
A plate-like spring body extended to one of the two arms, one end of which is connected to the distal end of the plate-like spring body, and the other end of which is connected to the other of the two arms; A cable body in which a tension spring is interposed in the middle, and a strain gauge that is attached to the plate-shaped spring body and changes the electrical resistance value according to the degree of curvature of the plate-shaped spring body; A strain gauge type displacement meter, wherein the displacement amount of the displacement body is measured by being transmitted to the strain gauge.