JPS6055005B2 - Test piece elongation measuring device in material testing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a test piece elongation measuring device capable of measuring long elongation and fine elongation of a test piece such as rubber or plastic that has a large elongation.

When measuring the elongation of a test piece such as rubber or plastic, which elongates significantly under tensile load, the measuring device attaches a lever piece of the measuring device to the test piece, and moves the lever according to the elongation. The main method used is to move the piece using a servo mechanism or the like and measure the amount of movement.

By the way, the accuracy of a measuring device that targets such a test piece with a large elongation is low due to its large measuring range and especially because the measurement lever that contacts the test piece of the measuring device is moved and the measurement is performed based on the amount of movement. In particular, the accuracy of minute elongation measurements is extremely low.

In measuring the elongation of such a test piece, it is desirable to be able to accurately measure both minute elongation and long elongation.
The present invention aims to provide a test piece elongation measuring device for a material testing machine that can meet such demands.

FIG. 1 is a block diagram showing the configuration of a test piece elongation measuring device of the present invention.

In the figure, 1 indicates a load cell that measures the load applied to the test piece 26 (Figure 2) by a material testing machine (not shown), and 2 indicates a recorder that measures the load, elongation, etc. show. Reference numerals 17 and 18 indicate detectors that are components of the displacement detection levers DL and DL' attached to the test piece 26, and their configurations are shown in detail in FIGS. 2 and 3.

That is, in FIG. 2, DL and DL' are displacement detection levers, and lever pieces 22' and 23' are respectively attached to the test piece 26, lever bases 22 and 23 are moved by a servo mechanism to be described later, and detection levers DL and DL' are displacement detection levers. It is composed of vessels 17 and 18.

The configuration of the detectors 17 and 18 is, for example, as shown in FIG.
The lever piece 23'' is configured to be able to tilt freely at the center, and the Magnescale 40 detects the inclination of the lever piece 23'' due to the elongation of the test piece 26.The Magnescale 40 outputs a pulse signal proportional to the inclination angle as a detection signal. occurs as 37
is a restoring spring.

In addition, 24 and 25 are the lever pieces 22'' and 23'', and the test piece 26
A knife edge or the like is used as a fixture to be attached to the test piece 26, and the lever pieces 22'' and 23'' are structured to be rotatable relative to the test piece 26.

Further, the lever pieces 22'' and 23'' are extendable and retractable so that as the test piece 26 extends, the lever pieces follow. When a detection signal generated by the inclination of the lever pieces 22'' and 23'' is input to the servo mechanism as described later, the servo motors 7 and 8 are rotationally driven, and the output drives the pulleys 30 to 33 and the lobe 38. , 39 is driven to connect the lever base 22 via the connectors 34, 35.
, 23 are moved.

This is a so-called automatic balancing method, and almost no measuring force acts on the test piece 26. In this way, the displacement detection lever DL,
When DL'' detects the elongation of the test piece, the detection signal activates a servo mechanism and an actuating mechanism to move the displacement detection levers DL and DL'' along the elongation of the test piece. However, such a configuration is conventionally known.

In addition, in FIG. 2, 28 and 29 are lever bases 22 and 2.
3 along the direction of elongation of the test piece 26, and is guided by a guide rod 27 suspended vertically from the machine frame F of the testing machine. As described above, the test piece elongation measuring device according to the first embodiment of the present invention follows the elongation of the test piece using the servo mechanism and the operating mechanism, and performs the test based on the amount of movement. A detection mechanism that sensitively detects the elongation of the test piece is installed on the displacement detection lever that measures the elongation of the test piece. More specifically, the displacement detection lever detects when the test piece stretches and issues a detection signal to transmit the stretch to the servo mechanism. The structure is such that a detection signal can be generated in proportion to the amount of elongation. This is because, as mentioned above, the lever pieces 22'' and 23'' are tilted with respect to the lever bases 22 and 23 due to the elongation of the test piece 26, and the detectors 17 and 18 detect this. be.

Therefore, in the present invention, until the elongation is within a certain range, the detection signals from the displacement detection levers DL and DL'', specifically the detection signals from the detectors 17 and 18, are transmitted to the recorder 2 which performs elongation display recording. , and for further elongation, a servo mechanism and an actuating mechanism are operated to input the amount of movement of the displacement detection levers DL, DL'' or a signal corresponding thereto to the recorder 2. Such a configuration is clear from the block diagram in FIG. 1, and the outputs (detection signals) from the detectors 17 and 18 are also input to each servo mechanism as described later. 6 is also input to the recorder 2 via the circuit changeover switch 20, and is used to record the elongation-load (on L) curve and the like.

In this case, the detection signal input to the control circuit 6 is a detection signal corresponding to minute elongation of the fixed displacement detection lever, and its output is E. Regarding the configuration in which the servo mechanism and the actuation mechanism are operated by detection signals from the detectors 17 and 18,
The detector 17 and its associated servo mechanism (displacement detection lever DL) will be described below as a representative example. The detection signal is input to the servo amplifier 9 via the switch 15, and the output of the servo amplifier 9 drives the servo motor 7 to rotate, and the potentiometer 4 operates in accordance with the amount of rotation. . This potentiometer 4 is interlocked with the movement of the displacement detection levers DL, DL'', and the output from the potentiometer 4 is input to the control circuit 6.
The signal is output as a long elongated signal E1 and inputted to the recorder 2 via the circuit changeover switch 20. by the way,
The detection signal from the detector 17 is not entirely input to the servo amplifier 9, but is input when the switch 15 is activated.

That is, the elongation of the test piece 26 is minute at first, and at this time, the lever piece 22'' only tilts with respect to the lever base 22, emitting a minute detection signal, and the switch 15 is not activated. The detection signal at this time is only output to the control circuit 6 and input to the automatic setting device 11.This setting device 11 outputs a signal when the inclination of the lever piece 22' with respect to the lever base 22 reaches a predetermined value. When the switch 15 is activated, the switch 15 is automatically actuated, and from then on, when the predetermined inclination angle is reached, this is used as a reference inclination angle signal and the detection signal is sent to the servo mechanism (servo amplifier). .
Therefore, in subsequent elongation measurements, the output from the potentiometer 4 will be input to the recorder 2 as a signal El. The above operation is the same for the other displacement detection lever DL'', its servo mechanism, and operating mechanism.

That is, 5 is a potentiometer, 8 is a servo motor, 1
0 is a servo amplifier, 12 is an automatic setting device, and 16 is a switch. 3 is a pulse generator that converts the signal (analog signal) outputted from the potentiometers 4 and 5 via the control circuit 6 into pulses and outputs the elongation amount in pulse form at regular intervals, as shown on the right side of the recorder 2. This is useful when recording hourly loading (LT) or hourly elongating (ET) records.

Reference numeral 19 denotes a changeover switch for switching and inputting the output from the load cell 1 and the output from the pulse generator 3 to the recorder 2.

As is clear from the configuration of FIG. 1, according to the present invention, the elongation of the test piece is relatively small at the beginning of the test (
When detecting slight elongation, the accuracy is improved by detecting the displacement with a detector inside the displacement detection lever (a detector using a detection method based on the inclination angle), instead of using a servo mechanism to displace the displacement detection lever as in the past. When the elongation reaches a predetermined value or more, the servo mechanism and operating mechanism are activated to move the displacement detection lever and the elongation is measured from the amount of movement or from a signal corresponding to the amount of movement. It is designed to measure elongation with high accuracy.

However, due to the type of test piece or other conditions, it is not necessary to carry out minute elongation measurements up to a predetermined value.
When the value is appropriate, it is necessary to switch to elongation measurement using a servo mechanism.

In that case, the setting device is not automatic, but a manual setting device that can set the value manually at an appropriate time is required. FIG. 4 shows an embodiment in this case, in which numeral 13 is a manual setting device.
FIG. 4 is not a block diagram showing the entire device as in FIG. 1, but a block diagram showing only the main parts centering around the switch 15 and setting device 13.

The manual setting device 13 includes a device that allows the operator to immediately actuate a switch 15 manually (by pressing a button) when it is necessary to switch the measurement method based on the value while looking at the recorder 2. In this case, manual operation is also possible when the value is zero. The present invention includes those in which either a manual setting device or an automatic setting device is installed. The test piece elongation measuring device according to the second embodiment of the present invention is equipped with an automatic setting device and a manual setting device, and can be applied to testing any material.

This configuration is shown in FIG. FIG. 5 is a block diagram showing only the main parts like FIG. 4, but in the figure there are 11
1 is an automatic setting device, and 13 is a manual setting device.
Reference numeral 14 denotes a changeover switch for inputting the detection signal from the detector 17 into the automatic setting device 11 or the manual setting device 13, and is an essential component.

15'' is a switch that is activated by a signal from the setting device 11 or 13, and when activated, a detection signal is input to the servo amplifier 9.

The test piece elongation measuring device in the material testing machine of the present invention can be modified in several ways other than the above.

A first variant is a displacement detection lever, in particular a detector among its components.

Not only the displacement detection method using Magnescale, but also a differential transformer or strain gauge type detector can be applied. The second modification is a servo mechanism, an actuation mechanism,
In particular, the actuation mechanism is not limited to a pulley-lobe mechanism as shown in FIG.

The third modification is an elongated display and recording system, but this is of course a configuration that is not included in the constituent requirements of the present invention, but is not limited to only recorders such as the illustrated example, and is applicable only to digital display meters. It may also be from.

If a pulse encoder is attached instead of extracting a voltage (analog) signal from a potentiometer, a pulse converter will be unnecessary. In other words, there is a method in which pulses are output from the rotation of a pulley or the like of an operating mechanism. The present invention is as described above, and it is possible to measure both minute elongation and long elongation with good accuracy not only in rubber and plastics but also in any other materials.

It is particularly useful for testing specimens with large elongation, and greatly contributes to the analysis and research of those materials.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the entire device of the present invention, Fig. 2 is a schematic diagram mainly showing the displacement detection lever and its operating mechanism, Fig. 3 is an enlarged view of the main parts of the displacement detection lever, and Fig. 4 , FIG. 5 is a block diagram showing the configuration of the present invention. 1...Load cell, 2...Lucoder, 4
, 5... Potentiometer, 6... Control circuit, 7, 8... Servo motor, 9, 10...
... Servo amplifier, 11, 12 ... Automatic setting device, 13 ... Manual setting device, 14 ...
・Selector switch, 15, 15″, 16... Switch, 17, 18... Detector, 19, 20...
...Selector switch, 22, 23...Rubber base, 22'', 23゛...Rubber piece, 24,25...
...Fixing tool, 26...Test piece, DL, D
L''...Displacement detection lever, 30-33...
...Pulley, 38,39...Lobe, 34,3
5... Connector, 40... Magnescale, 36... Zen, 37... Restoration spring.

Claims (1)

[Claims] 1. A lever piece attached to a test piece, a lever base that holds this lever piece in a tiltable manner, and a detection signal proportional to the inclination angle when the lever piece is tilted with respect to the lever base due to the elongation of the test piece. a servo mechanism that rotationally drives a servo motor based on the detection signal; an operating mechanism that moves the lever base along the elongation of the test piece by rotation of the servo motor; and a lever piece. and a setting device that transmits the detection signal to the servo mechanism when the inclination angle reaches a predetermined value when the lever piece is tilted with respect to the lever base due to the elongation of the test piece, and the lever piece is tilted with respect to the lever base. In a materials testing machine, the minute elongation of the test piece can be measured using the detection signal generated by the lever, and the long elongation of the test piece can be measured from the signal corresponding to the amount of movement of the lever base caused by the actuating mechanism. Test piece elongation measuring device.