JPS63269040A - Tensile tester - Google Patents

Abstract

PURPOSE:To measure not only the minute elongation but also the large elongation of a sample large in tensile deformation quantity with high accuracy by one test, by together providing two TV cameras scanning a sample piece in different regions. CONSTITUTION:A tensile mechanism containing chucks 1a, 1b is received in a thermostatic tank 6 having a cooling tank 5 and TV cameras 10, 11 are arranged outside a perspective part 7 so as to face to the tensile mechanism. The camera 10 equipped with a zoom lens performs magnifying scanning in such a state that the whole visual field thereof is limited to the local region at an early stage of tension and mainly detects the low elongation region of a sample piece S while the camera 11 is set so that the visual field thereof faces to an entire tensile deformation region until the sample piece S is broken and mainly detects the high elongation region of the sample piece S. The respective cameras alternately scan the respective allotted regions under the control of a CPU 9. The result of the tensile characteristic of the measured sample piece S is sent to a printer 16.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a tensile testing device that measures the tensile properties of a sample using a scanning device such as a television camera or a line sensor camera.

[Prior art]

In tensile test equipment that measures tensile properties such as elastic modulus, elongation stress, and elongation at break of samples such as rubber, resin, and fiber,
In order to eliminate the complexity and errors that occur when measuring tensile changes in a sample piece with the naked eye, measurement marks with different optical properties are applied to the sample piece, and the marks are scanned by a scanning device such as a television camera (hereinafter simply referred to as a TV camera). Automatic measurement using the method has already been proposed by the present inventors in Japanese Patent Publication Nos. 19882-1982 and 18086-1986.

On the other hand, for samples such as rubber, which undergo a large deformation of 5 to 10 times before breaking, it is necessary to investigate not only the elongation characteristics when the large deformation occurs, but also the characteristics of minute deformation in the low elongation region. There are cases where However, in all of the conventionally proposed tensile test apparatuses described above, the elongation of one or more sample pieces is measured using one TV camera. Therefore, if you bring the TV camera close to the sample piece, you can read even minute elongations, but for large elongations, the T
Since it is out of the field of view of the V camera, it becomes impossible to measure it. On the other hand, if the TV camera is moved away from the sample piece, elongation due to large deformation can be detected, but this results in a problem in that the accuracy of reading minute elongation decreases. Such problems also occur when a line sensor camera is used as a scanning device.

[Purpose of the invention]

The purpose of the present invention is to provide a tensile test that enables even when measuring a sample with a large amount of tensile deformation, to be able to measure minute elongations with high precision, and to simultaneously measure large elongations in a single test. The goal is to provide equipment.

[Structure of the invention]

To achieve the above object, the present invention deforms a sample piece with measurement marks having different ground colors and optical properties by applying a tensile load in the longitudinal direction, and scans changes in the measurement marks with a scanning device. It is based on a conventionally proposed tensile testing device for measuring properties, and the scanning device is one that enlarges and scans a local area of a sample piece as a whole field of view.
This apparatus is characterized in that at least two apparatuses are installed together, one for scanning the entire area of the sample piece as a whole field of view.

In addition, in the present invention, in order to enable high-precision reading, it is preferable to configure the sample piece to be pulled at a variable speed. In the high elongation range exceeding this range, it is preferable to pull at a normal speed higher than this. The low velocity region at this time depends on the type of sample piece, but is 0.5 to 501
The normal speed is preferably in the range of 50 to 500 mm/min. In addition, the boundary region when switching the tensile speed is when the elongation rate is 1.0 to 5.
It is preferable to set it within the range of 0.0%.

Such a pulling speed should be coupled to the operation of two scanning devices, such that at low speeds the scanning device provides a full field of view in a local area, and at normal speeds the scanning device provides a full field of view over the entire area. Preferably, the scanning device is activated and it switches automatically.

It is sufficient to have two scanning devices, one that has a full field of view for the local area of the sample piece and one that has a full field of view for the entire area of the sample piece, but three or more units may be used if necessary. There is no problem.

A known TV camera or line sensor camera used for industrial or broadcast purposes can be used as this scanning device, and a zoom lens may be attached to the camera that has a full field of view in a local area. Such a camera is, for example, a commercially available CCD camera TJ-22AII model (NEC) with an effective number of scanning lines of 378 horizontal x 485 vertical pixels.
etc. can be used effectively.

A tensile test piece as specified by JIS is used as the sample piece. An example of this is shown in FIG. 2A, in which marked lines Q and Q are attached to the surface of the sample piece S as measurement marks at two locations separated in the longitudinal direction (pulling direction). This sample piece S has optical characteristics different from the ground color and the color of the marked line Q, and it is particularly preferable that the brightness of the marked line Q is higher than that of the ground color. For example, it is preferable to select black or a dark color as the background color of the sample piece S, and select white or a bright color for the marked line Q.

FIGS. 2A and 2B are principle diagrams illustrating a method of measuring tensile properties using a scanning device while pulling such a sample piece S in the longitudinal direction.

As shown in the figure, if a tensile load is applied to the sample piece S to make it elongate, and the image of the sample piece S is captured by, for example, a TV left camera, the direction of the scanning line H5 is shown in FIG. 2A. When the direction is perpendicular to the direction, the output signal is outputted from the portion P0. Po appears at a higher level than other parts. Therefore, among this TV left camera output signal, constant 12 and bell 8
Only the signal of 1 or more is taken out by the processing circuit, and the above marked line Q,
It is sufficient to obtain only signals at time intervals corresponding to the interval Q and calculate the distance between the gauge lines from the signal.

The present invention will be explained below using a tensile test apparatus according to an embodiment shown in FIG.

In FIG. 1, la and lb are an upper chuck and a lower chuck that grip both ends of the sample piece S, respectively. The upper chuck 1a is installed at a fixed position, and a load cell 2 for detecting a tensile load is connected to the upper end side. Then, the tensile load detected by the load cell 2 is transmitted to the amplifier 1.
2 to the central processing unit 9. On the other hand, the lower chuck 1b is moved up and down by the drive of a motor 4 via a gear box 3, so as to apply a tensile load to the sample piece S. This motor 4 is driven by a command from the central processing section 9 via a motor control section 13.

The tensioning mechanism including the upper and lower chucks la and lb is housed in a constant temperature bath 6 having a cooling coil 5. Further, a see-through section 7 made of double glass is provided on the side surface of the thermostatic chamber 6, so that it can be visually observed from the outside. Dry hot air is passed through the space 8 of the see-through section 7 to prevent dust from forming on the glass surface due to dew condensation.

This constant temperature bath 6 is provided to measure the characteristics of the sample under low temperature conditions, and is not necessarily necessary for measuring the characteristics at room temperature.

Two TV right cameras 0.11 are installed outside the transparent section 7 so as to face the tension mechanism inside. Each camera is shown in Figure 2A.

The detected electric signal as shown in B is processed by the video circuit 14,
It is designed to be inputted to the central processing unit 9. Further, the output signal processed by this video circuit 14 can be monitored by a mi-monitor TV 15.

One of the two cameras, TV right camera 0, is equipped with a zoom lens, and its entire field of view is limited to the local region at the initial stage of tension and is used to enlarge and scan, mainly to detect the low elongation region of the specimen S. It has become. By limiting the entire field of view to a local area in this way, it is possible to read even minute displacements with high precision.

For example, the above-mentioned CCD camera TJ-22AII type is used as the TV right camera 0, its entire field of view is limited to a local area of, for example, 25 mm using a zoom lens, and the effective number of vertical pixels is set to 450. shall be made. In addition, a normal tensile test piece according to JISa No. was used as the sample piece S, and this sample piece was pulled to obtain the initial marked line Q.
, the distance between Q is 20111111 of the above full field of view limit.
Suppose we add 25% elongation to 51. Then, the displacement that can be read by this TV left camera is 25mm/4
50 pieces = 0. It has an extremely high precision of up to Q5n+m/piece.

In addition, the other TV camera 11 of the two cameras is not equipped with a zoom lens, and its entire field of view is designed to view the entire tensile deformation region of the sample piece S until it breaks, and mainly focuses on the sample piece S. This is to detect high elongation regions.

The above two TV right cameras 0.11 are operated by the former's T
The V right camera 0 performs scanning, but when the specimen S exceeds a preset elongation rate and extends into a high elongation region, the camera operation is switched and the latter TV camera 11 begins scanning. . Further, the central processing section 9 controls the pulling speed of the lower chuck 1b via the motor control section 13 so as to change it. In the low elongation region, the speed is set to low, but when the elongation rate exceeds a predetermined elongation rate, the speed is switched to the normal speed, which is faster than this.

The results of the tensile properties of the sample piece measured through such operations are output from the central processing unit 9 to the printer 16. 17 is a keyboard for inputting data necessary for measurement.

As mentioned above, the above-mentioned tensile test apparatus is equipped with at least two TV cameras, one of which is a high-precision extensometer dedicated to the low elongation region, and the other one is a normal extensometer. When S reaches a preset elongation rate, the TV camera is automatically switched from a high-precision extensometer to a normal extensometer. Therefore, it is possible to accurately read the elongation rate of the sample piece from the start of tension to the time of cutting.
In particular, it is possible to read the elongation rate (0.2 to 20%) in the low elongation region with an accuracy of ±0.2%.
4゜Also, if the tensile speed is also switched at a preset elongation rate as in the above example, the low elongation modulus is measured in the low elongation region at low speed, and then the high elongation modulus is measured in the high elongation region at normal speed. It can be made to measure. Therefore, a plurality of tensile properties can be measured simultaneously in one test.

〔Effect of the invention〕

As described above, the tensile test apparatus of the present invention is equipped with at least two scanning devices: one that scans a local area of the sample piece as a full field of view in an enlarged manner, and one that scans the entire area of the sample piece as a full field of view. As a result, even if the sample has a large amount of tensile deformation, the former scanning device can measure minute extensional deformations with high precision, and the latter scanning device can measure large extensional deformations. . Therefore, it becomes possible to simultaneously and easily measure a plurality of tensile properties in one test.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a tensile test apparatus according to an embodiment of the present invention;
FIGS. 2A and 2B are explanatory diagrams of the principle of a tensile test apparatus using a scanning device. 1a... Upper chuck, 1b... Lower chuck, 9
... Central processing unit, 10... (with zoom lens) T
V camera, 11...TV camera, 14...video circuit, S...sample piece, Q...marked line (measurement mark).

Claims (3)

[Claims] (1) A sample piece with measurement marks with different ground colors and optical properties is deformed by applying a tensile load in the longitudinal direction, while a scanning device scans the changes in the measurement marks, and electricity is output depending on the difference in optical properties. In the apparatus for measuring the tensile properties of the sample piece from a signal, the scanning device includes a scanning device that enlarges and scans a local area of the sample piece as a full field of view, and a scanning device that scans the entire area of the sample piece as a full field of view. A tensile testing device characterized by being equipped with at least two of the following. (2) The tensile test device according to claim 1, wherein the tensile speed is variable, and at least two scanning devices are switched and used in conjunction with the tensile speed. (3) The at least two scanning devices are television cameras or line sensor cameras, and the cameras for enlarging and scanning the local area of the sample piece as a whole field of view are equipped with zoom lenses. Tensile test equipment.