JPH05180742A - Extensometer - Google Patents

Abstract

PURPOSE:To enable accurate measurement of elongation without causing an error in measurement by a method wherein the respective edge fore-end members of a bench mark edge of a bench mark grip and a pressing piece are supported rotatably around an axis being parallel to a tensile axis, in relation to support members. CONSTITUTION:A bench mark edge 1 is constructed of an edge fore-end member 11 and a support member 12 thereof and the member 11 is supported rotatably around an axis extending virtually along a tensile axis CL, in relation to the member 12. A pressing piece 2 is also constructed of an edge fore-end member 21 and a support member 22 thereof and made to have quite the same structure as the edge 1. The members 11 and 21 are made to rotate freely in relation to the members 12 and 22 in accordance with the shape of the section of each bench mark part of a test piece W so that they hold the test piece W between them. When this test piece W is twisted back by a tensile load, too, each of the members 11 and 21 rotates to follow the twist, a lateral load is not transmitted to the members 12 and 22 nearly at all and thus no error occurs virtually in a measured value of elongation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an extensometer of a type in which a change in distance between two mark grips is directly detected by a displacement detector such as a differential transformer.

[0002]

2. Description of the Related Art In an extensometer using a displacement detector such as a differential transformer as a converter, the extensometer is attached to a test piece at a marked line grip provided at both ends, and a change in distance between the two marked line grips. Is transmitted directly to the displacement detector without using a lever or the like, and the elongation between the marked lines of the test piece is measured.

In such an extensometer, conventionally, a grip grip having a structure as illustrated in FIG. 4 is often used. That is, it has a straight edge,
A marked line edge 41 engaged with the converter via a transmission mechanism in the extensometer body 40 and a marked groove edge 41 that is moved toward and away from the marked line edge 41 by the rotation of the adjusting screw 42a, and has a V-groove shape at the tip. The test piece W is configured to be attached to the test piece W with the test piece W sandwiched between the marked line edge 41 and the pressurizer 42.

[0004]

By the way, in the case where a tensile test of, for example, a 7-strand wire rope is performed by using the conventional extensometer as described above, the test piece W when attached to the test piece W is used. The state of holding the edge to the
In some cases, a stable and close contact may be achieved as shown in FIG. 3, but in some cases, an unstable condition may be exhibited as illustrated in FIG. Even if it is mounted so that it is held stably in one grip (A), for example,
Since the two grips are oriented in the same direction, the other grip is inevitably in the condition (B) in relation to the twist pitch of the wire rope and the distance between the marked lines.

If the test is performed in a state where the test piece W and each edge of the grip are in unstable contact with each other as shown in (B), the marked line may be displaced. In addition, when a tensile test is performed on the test piece W on which the twist is applied, such as a wire rope,
As shown in (A) an external view and (B) an AA cross-sectional view, the tensile load P tries to restore the twist of the test piece W, so that an extra lateral load acts on the marked line edge, This causes a deviation of the marked line edge and causes a large measurement error.

The present invention has been made in view of the above circumstances, and it is possible to constantly and stably adhere a marked line edge or the like to a test piece even when a twisted test piece such as a wire rope is tested. The purpose of the present invention is to provide an extensometer that is capable of preventing the occurrence of measurement error even when the twist of the test piece returns during the test, and does not easily cause the deviation of the marked line edge.

[0007]

In order to achieve the above-mentioned object, in the extensometer of the present invention, each of the marked line edges of the two marked line grips and the pressurizer arranged opposite thereto support each other. It is characterized in that it is rotatably supported about an axis parallel to the tensile direction of the test piece with respect to the support member.

[0008]

[Operation] The marking line edge and the pressurizer are not formed into an integral structure, but are separated into an edge tip portion that abuts on the test piece and a support member, and the edge tip portions of the test piece and the support member are separated from each other. By supporting the test piece so that it can rotate about an axis parallel to the pulling direction, the edge of each edge should be able to sandwich the test piece with its posture freely changed around the axis according to the outer shape of the test piece. Even if the twisting of the test piece returns due to the tensile load, only the edge tip part rotates following it, so the lateral load due to the twisting back is not transmitted to the support member, Can achieve the purpose of.

[0009]

EXAMPLE FIG. 1 is a front view showing an extracted part of a reference line grip of an extensometer of the present invention, and FIG. 2 is a plan view thereof. The marked line edge 1 is constituted by an edge tip member 11 and its supporting member 12, and the edge tip member 11 is rotatably supported with respect to the supporting member 12 about an axis substantially along the tensile axis CL.

That is, the front end surface of the support member 12 is formed with a concave groove 12a having an arcuate bottom surface, and the rear end surface of the edge tip member 11 has a thickness to fit into the concave groove 12a. , And a projection 11a having an arcuate end surface having a curvature equivalent to that of the arc is formed, and the edge tip member 11 is formed on the surface of the edge tip member 11 in a state where the end surface of the projection 11a is in surface contact with the bottom surface of the concave groove 12a. Support member 1 that can be rotated along
2 is supported. Here, in order to ensure the above-mentioned surface contact, a tension coil spring 13 is provided between the edge tip member 11 and the support member 12.

The pressing element 2 is also composed of an edge tip member 21 and a supporting member 22 thereof, and the edge tip member 21 has an arcuate end face formed on its rear end face due to the structure exactly the same as that of the marked line edge 1 described above. The protrusion 21a has a concave groove 2 having an arc-shaped bottom surface formed on the front end surface of the support member 22.
2a, the arcuate surfaces are in surface contact with each other, and are rotatably supported by the support member 22 about an axis substantially along the tension axis CL, and the surfaces are also supported. A tension coil spring 23 is provided to ensure the contact.

Further, the protrusions 11a and 21a of the edge tip members 11 and 21 have pins 11b and 2 on their upper surfaces.
1b is fixed and the pins 11b, 21
b is an arc-shaped long hole 1 formed in each of the support members 12 and 22.
It is fitted in 2b and 22b, and this structure prevents each edge tip member 11 and 21 from coming off from each support member 12 and 22.

The support member 12 of the marked line edge 1 is connected to a converter such as a differential transformer through a member provided inside the extensometer body as in the conventional case, but the structure thereof is the same as in the conventional case. This is exactly the same as the extensometer of the kind, and the support member 22 of the presser 2 is also connected to the presser adjusting screw as in the conventional case.

The marking edges 1 and the support members 12 and 22 of the pressure element 2 are elastically pressed by the compression coil springs 14 and 24 from the rear end sides thereof,
Although the test piece W is configured to be advanced by the reduced diameter of the test piece W due to the tensile load P, this point is also similar to the conventional case.

The structure of the marked line grip as described above is common to the two grips, and in the extensometer of the embodiment of the present invention, such two marked line grips grip the upper and lower marked lines of the test piece W. The test piece W is mounted in this state.

FIG. 3 is an explanatory view of the operation of the embodiment of the present invention, and the operation will be described below with reference to this drawing. For example, when mounting the embodiment of the present invention on a twisted test piece W such as a wire rope, as shown in FIG. 3 (A) or (B), depending on the cross-sectional shape of each marked line portion of the test piece W. By freely rotating the edge tip members 11 and 12 with respect to the support members 12 and 22 and sandwiching the test piece W, the test piece W can be always held in a stable contact state.

Even when such a test piece W is untwisted by a tensile load, each edge tip member 11, 21 is
However, the lateral load is hardly transmitted to each of the support members 12 and 22, and the measurement value of elongation hardly causes an error.

Here, the edge tip member 1 of the marked line edge 1
It is conceivable that the distance from the displacement detector may change when 1 rotates due to the change in the shape of the test piece W in the abutting portion, but in this type of extensometer, the distance is directly measured without using a lever or the like. In addition, since the distance between the marked grips is measured by the displacement detector, it does not affect the measured value of elongation.

In the above embodiment, the guide method for the rotation of each edge tip member with respect to the support member is carried out by the contact between the arcuate surfaces formed on the end surface portions of both edges, but the present invention is not limited to this. Without limitation, for example, guide by spherical contact (however, in this case, it is necessary to regulate rotation other than around the axis parallel to the pulling axis), or guide by pin joining, and other known guide methods Of course, can be adopted.

The rotation center axis of each edge tip member is
In particular, it is not necessary to match the tension axis with the tension axis, and it suffices if it is parallel to the tension axis.
It is preferable that the central axis of rotation is closer to the tensile axis.

[0021]

As described above, according to the present invention, the marking edge and the presser of the marking grip are divided into the edge tip member and the support member, and each edge tip member is attached to the support member. Since it is rotatably supported around an axis parallel to the tension axis, even when it is attached to a twisted test piece such as a wire rope, each edge tip member can be used according to the cross-sectional shape of the test piece at the attachment part By rotating it freely, it is possible to always wear it stably,
Even if the twisting of the test piece returns during the test, each tip edge member rotates accordingly, so the possibility of deviation of the marked line is extremely small, and the lateral load due to the twisting back is applied to each supporting member. It did not work, and it became possible to measure the elongation accurately without any measurement error.

[Brief description of drawings]

FIG. 1 is a front view showing an extracted portion of a marked line grip according to an embodiment of the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is an explanatory view of the operation of the embodiment of the present invention.

FIG. 4 is an external view showing a structure of a conventional grip of an extensometer.

FIG. 5 is an explanatory view of the contact state of the edge when the gauge grip of the conventional extensometer is attached to the wire rope.

FIG. 6 is an explanatory diagram of behavior when a tensile load is applied to a twisted test piece.

[Explanation of symbols]

 1 ...- Marked edge 11 ... Edge tip member 11a ... Protrusion 11b ... Pin 12 ... Support member 12a ... Recessed groove 12b ... Arc length Hole 13 ・ ・ ・ ・ Tension coil spring 14 ・ ・ ・ Compression coil spring 2 ・ ・ ・ ・ Pressure element 21 ・ ・ ・ ・ Edge tip member 21a ・ ・ ・ ・ Projection 21b ・ ・ ・ ・ ・ ・ Pin 22 ・ ・ ・Member 22a ... Recessed groove 22b ... Arc-shaped long hole 23 ... Extension coil spring 24 ... Compression coil spring

Claims (1)

[Claims] 1. An extensometer for measuring the elongation of a test piece by detecting a change in the distance between two mark grips attached to a test piece by using a displacement detector. The marked line edge and a presser for pressing the test piece in opposition thereto are provided, and the marked line edge and the presser are parallel to the supporting member supporting each in the pulling direction of the test piece. An extensometer characterized by being rotatably supported around a shaft.