JPH0758194B2 - Extensometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an extensometer. Specifically, by detecting the displacement of the reference point of the sample using a circular moving body,
The present invention relates to an extensometer capable of stably measuring the elongation of a sample with high accuracy.

[Problems to be Solved by Prior Art and Invention] A lever type gripping arm is used as an extensometer having a mechanism for detecting the displacement of a gauge point of a sample and a tracking mechanism for tracking the displacement of this gauge point. There is known an extensometer of a type in which a gauge point portion of a sample is held at one end portion and a displacement detector is installed at the other end portion via a fulcrum.

In this type of extensometer, it is necessary to use a long gripping arm in order to obtain a certain degree of sensitivity, but when doing so, it is likely to become unstable.

 The bending of the gripping arm cannot be ignored.

The shock when the sample breaks also becomes large, and the influence on the detector becomes large.

 Attaching a protective mechanism complicates the structure.

 The size of the device increases.

However, there is a demand for a device that is not sufficiently satisfactory, and that is stable and can perform highly accurate measurement.

[Means for Solving the Problems] As a result of earnest studies to improve the above-mentioned drawbacks, the present inventor found that as a mechanism for detecting the displacement of the reference point of the sample,
The present invention has been completed based on the knowledge that the above drawbacks can be greatly improved by detecting the displacement of the reference point by using a circular moving body having an axis instead of the lever type.

That is, the present invention is intended to provide an extensometer capable of stably measuring the elongation of the sample with high accuracy, and the gist thereof is to detect the displacement of the gauge point of the sample and measure the displacement amount. In an extensometer having a detection mechanism that emits a signal according to and a tracking mechanism that tracks the displacement of the gauge point by the signal, as the detection mechanism, in a plane that is substantially orthogonal to the surface of the sample and includes the displacement direction of the gauge point. A circular moving body that has a circular motion and has an axis is brought into contact with a gauge point to detect the displacement of the gauge point as an arc motion, and the displacement of the gauge point is detected by an angle measuring device provided on the axis of the circular body. The extensometer is characterized by using a detection mechanism that

Targets for measuring gauge displacement using the extensometer of the present invention include industrial materials such as plastic, rubber, metal, and wood, and the extensometer is usually used with a tensile tester or a similar device. It

The extensometer of the present invention is characterized by a detection mechanism for detecting the displacement of the gauge mark, and a conventionally known tracking mechanism can be used. As a specific example of the tracking mechanism, the base on which the detection mechanism is loaded is moved up and down with a belt or a feed screw, and the amount of vertical movement is detected by a detector such as a magnescale or encoder. There is a system that performs tracking by comparing the displacement amount with.

Hereinafter, the detection mechanism of the present invention will be described with reference to the drawings.

FIG. 1 is a sketch showing an example of the detection mechanism of the extensometer of the present invention. FIG. 2 is a partially cutaway side view of the circular moving body of the detection mechanism.

In the figure, 1 is a sample, 2 is a reference point, 3 is a circular moving body, 4
Is a connector for connecting a circular moving body and a shaft, 5 is a shaft, 6 and 6'are bearings,
Reference numeral 7 is a detector, 8 is a base of the detection mechanism, 9 is a tracing stylus, 10 is a tracing stylus shaft, 11 is a spring, and 12 is a support provided to face the tracing stylus 9.

The sample 1 is attached to the tensile tester (not shown) at the top and bottom thereof and tensioned. The reference mark 2 is a fine mark provided on the surface of the sample 1. Although only one is shown in the figure, it is usually provided above and below the sample 1, and the tip of the probe 9 of the circular moving body 3 is brought into contact with each. It is preferable to provide a support tool on the back side of the gauge point 2 so that the contact state of the probe 9 does not change. Specific examples of the support include those having the same shape as the probe 9, such as the support 12 shown in FIG.

As the circular moving body 3, a cylindrical body having an arrow-shaped probe 9 is shown in the figure, but the shape is limited to this as long as it has a member that comes into contact with the gauge point 2 and can perform circular movement. Not a thing. FIG. 2 shows an example of a circular moving body. In the circular moving body 3, a tracing stylus shaft 10 connected to the tracing stylus 9 is housed, and the tracing stylus 9 is attached to the gauge mark 2 of the sample 1. The tracing stylus shaft 10 is pushed forward by a spring 11 so as to make sufficient contact. It is preferable that the tip of the contact point 9 comes into point contact with the gauge point 2 in order to prevent an error due to slippage.

The size of the circular moving body 3 is preferably selected from the range of 20 to 40 mm from the center line of the shaft 5 to the tip of the probe 9.
If this length is too long, the device becomes large and the angle for detecting the displacement of the gauge mark 2 becomes small. On the contrary, if the length is too short, the angle for detecting the displacement of the gauge 2 can be increased, but slippage may occur between the gauge 2 and the probe 9. The angle of rotation of the circular moving body 3 depends on how the base 8 is tracked, but it is usually set within 2 °, preferably within 1 °.

The connector 4 for connecting the circular motion body and the shaft is a member that holds the circular motion body 3 and transmits the rotation of the circular motion body 3 to the shaft 5, and may be formed integrally with the circular motion body 3. The shaft 5 rotates in response to the displacement of the gage mark 2, but it is necessary that the shaft 5 rotates smoothly and has no play. Further, the bearings 6 and 6 ′ have a certain length.
It is good to take a wide space. Preferably, the shaft 5 is housed in a circumscribing pipe and the entire pipe is used as a bearing. In such a case, extremely accurate measurement becomes possible. As the detector 7, various measuring devices can be used as long as they can measure a minute angle, but for example, an encoder, a displacement sensor or the like is preferably used.

For the amount of extension between gauge marks, the sum of the tilt angle of the circular moving body 3 obtained by the detector 7 and the amount of movement of the base 8 of the detection mechanism is calculated for both the upper and lower gauge marks. However, it is represented by the difference between the two.

The base 8 of the detection mechanism follows a fixed amount of movement when the value of the detector 7 exceeds a set value. In this case, the error due to the delay in the movement of the base 8 of the detection mechanism does not become an error because it is corrected by the detector 7.

[Effect of the Invention] The extensometer of the present invention has a simple structure, has few failures, and can stably and accurately measure the elongation of a sample. Moreover,
If the length of the circular movement is relatively short, the accuracy tends to be good, and the device can be downsized. Further, even if the sample breaks, the shock can be escaped by the rotation of the circular motion body, so that there is no fear of damage to the device due to the break of the sample.

[Brief description of drawings]

FIG. 1 is a sketch showing an example of the detection mechanism of the extensometer of the present invention. FIG. 2 is a partially cutaway side view of the circular moving body of the detection mechanism. 1 ... Sample, 2 ... Gage mark, 3 ... Circular moving body 4 ... Connection between circular moving body and shaft, 5 ... Shaft 6, 6'bearing, 7 ... Detector 8 ... Detection mechanism Base, 9 ... Measurement element 10 ... Measurement element axis, 11 ... Spring 12 ... Supporting device provided facing the measurement element 9

Claims (1)

[Claims] 1. An extensometer having a detection mechanism for detecting a displacement of a gauge point of a sample and emitting a signal corresponding to the displacement amount and a tracking mechanism for tracking the displacement of the gauge point by the signal, wherein the detection mechanism is a sample. The surface of the circle is a circle moving body that is circularly moving in a plane that includes the displacement direction of the gauge point and has an axis that is in contact with the gauge point to detect the displacement of the gauge point as an arc motion. An extensometer characterized by using a detection mechanism for detecting displacement of a gauge mark by an angle measuring device provided on the axis of a moving body.