JPH0726898B2 - Rubber-like sample tensile tester - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a tensile test device for measuring the tensile properties of a rubber-like sample using a scanning device such as a television camera, a line sensor camera, a laser scanner camera. Is.

[Prior art]

Eliminates the complexity and error when measuring the tensile change of a sample piece with the naked eye in a tensile tester that measures the tensile properties such as elastic modulus, elongation stress, and elongation at break of rubber-like samples such as rubber, resin, and fiber Therefore, it is already known from the present inventor that a measurement mark having different optical characteristics is provided on a sample piece and the measurement mark is automatically measured by using a scanning device such as a television camera (hereinafter, simply referred to as a TV camera). The proposal was made in Japanese Patent Publication No. 56-19882, Japanese Patent Publication No. 56-18086, etc.

On the other hand, for samples that undergo large deformation 5 to 10 times before breaking, such as rubber, it is necessary to investigate not only the elongation characteristics when large deformation occurs, but also the small deformation characteristics in the low elongation region. There is a case. However, in each of the above-mentioned conventional tensile testing devices, one TV camera measures the elongation of a single sample piece or a plurality of sample pieces. Therefore, if the TV camera is brought close to the sample piece, even a small amount of extension can be read, but a large amount of extension cannot be measured because it is out of the field of view of the TV camera. On the other hand, if the TV camera is moved away from the sample piece, the elongation of the large deformation can be detected, but this has a problem that the accuracy of reading the minute elongation is lowered. Such a problem also occurs when a line sensor camera or a laser scanner camera is used as the scanning device.

[Object of the Invention]

An object of the present invention is to provide a tensile test device for a rubber-like sample that can measure a minute elongation of a rubber-like sample having a large amount of tensile deformation with high accuracy and can simultaneously measure a large elongation in one test. To do.

[Structure of Invention]

The present invention to achieve the above object, a rubber-like test piece provided with a measurement mark having different ground color and optical characteristics, while deforming by applying a tensile load in the longitudinal direction, the deformation of the measurement mark is scanned by a scanning device. In the device for measuring the tensile property of the test piece from the electric signal output depending on the difference in optical property, the scanning device is composed of either a non-contact type television camera, a line sensor camera, or a laser scanner camera. , A scanning device having a large deformation area of the test piece as the entire visual field as the scanning device, and a scanning device of the large deformation area having a small deformation area of the test piece as the entire visual field, which is effective in a television camera More than the number of scanning lines, more than the number of effective pixels in a line sensor camera, or laser scanning. Features at least two of the scanning device with improved measurement accuracy and faster than the vibration speed at Kamera, is characterized in that said Possibility constructed switched at least two of the scanning device.

Further, in the present invention, in order to enable high-accuracy reading, it is preferable to configure the pulling speed when pulling the test piece to be variable, and pulling at a low speed in the low extension region,
In a high elongation region that exceeds a preset elongation rate, it is preferable to pull at a normal speed higher than this. The speed in the low speed region at this time is 0.5 to 5 depending on the type of test piece.
The speed is in the range of 0 mm / min, and the speed in the normal speed range is 50 to 500 mm /
It is preferably in the range of minutes. In addition, as a boundary area when switching such a pulling speed, the elongation rate is 1.0 to 5
It is preferable to set when the range is 0.0%.

Such a pulling speed should be linked to the operation of at least two traveling devices, the scanning device which operates the small deformation region as the entire field of view at low speed, and the large deformation region as the entire field of view at the normal speed. It is preferred to activate the scanning device and to switch it automatically.

As the scanning device in the present invention, it is sufficient if there are two scanning devices, one having a small deformation area of the test piece as the entire visual field and one having a large deformation area of the test piece as the entire visual field.
It is safe to use more than one table. This scanning device is a known TV camera (image pickup tube), line sensor camera (photoelectric conversion camera using a solid state line scanning element) or laser scanner camera (laser scanner and light receiving) that is used for industrial or broadcasting. It is possible to use a non-contact type device which is composed of any one of (a camera in which the light source side scans the line) by combining the devices.

In the present invention, the scanning device for the large deformation region and the scanning device for the small deformation region have different measurement accuracy.
For example, a TV camera has 512 and 1024 effective scanning lines, a line sensor camera has 512 and 4096 effective pixels, and a laser scanner camera has a vibration speed. 1/100 second / scan and 1 / 15,000
The second / scan cameras can be effectively used. A television camera that covers the small deformation area
A line sensor camera that uses a larger number of effective scanning lines than a large deformation area as the entire field of view is used. The number of pixels is larger than the number of pixels, and in the laser scanner camera, the one in which the vibration speed is increased and the measurement accuracy is increased is used for the scanning device that makes the small deformation region the entire field of view.

A tensile test piece as specified in JIS is used as the sample piece. An example of this is shown in FIG. 2A. Marks Q, Q are attached to the surface of the rubber-like test piece S as measurement marks at two positions apart in the longitudinal direction (pulling direction). There is. The test piece S is made such that the ground color and the color of the marked line Q have different optical characteristics, and it is particularly preferable that the lightness of the marked line Q is higher than that of the ground color. For example, choose a black or dark color as the ground color of the test piece S,
It is good to choose white or bright color. As the marked line to be applied to the test piece, as shown in FIG. 3A, a test piece S'having a marked area Q'in which the distance between the two marked lines Q and Q is entirely painted is applied. It can also be used.

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

As shown in the figure, while applying a tensile load to the test piece S to extend the test piece S, for example, by a TV camera, the scanning line HS direction is orthogonal to the tensile direction of the test piece S as shown in FIG. 2A. When the image is picked up in this way, the output signal of
As shown in FIG. B, the portions P ₀ and P ₀ corresponding to the marked lines Q and Q appear as higher level signals than the other portions. Therefore, among the output signals, only the signals with a constant level E ₁ or higher are taken out by the processing circuit, and if only the signals at the time intervals corresponding to the interval L between the marked lines Q and Q are obtained, the signal between the marked lines can be obtained. The distance L can be obtained.

FIG. 3 is a principle explanatory diagram in the case where an image is taken by a line scanning TV camera so that the scanning line HS is in the pulling direction of the test piece S ′ (FIG. 3A). In this case, as shown in FIG. 3B, the portion of P ₁ corresponding to the labeled area Q ′ appears as a high level output signal as compared with other portions. Therefore, the second
As in the case of the figure, the distance L can be obtained by extracting only the signal having a constant level E ₁ or higher by the processing circuit. Such an output signal can also be obtained in the case of a laser scanner camera.

On the other hand, in the case of the line sensor camera, the output signal is as shown in FIG. 3C, and the scanning time T of the marker area Q'is
The pulsed output signal has the number of pixels corresponding to.

Of course, in the present invention, it is also possible to use the test piece S having the marked lines Q, Q as shown in FIG. 2A when the scanning line is made the same as the pulling direction.

Hereinafter, the present invention will be described with reference to the tensile test apparatus of the embodiment shown in FIG.

In FIG. 1, reference numerals 1a and 1b denote an upper chuck and a lower chuck for gripping both ends of the test 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. And
The tensile load detected by the load cell 2 is input to the central processing unit 9 via the amplifier 12. on the other hand,
The lower chuck 1b is vertically moved by driving a motor 4 via a gear box 3 to apply a tensile load to the test piece S. This motor 4 has a motor controller 13
It is driven by a command from the central processing unit 9 via the.

The pulling mechanism including the upper and lower chucks 1a and 1b has a cooling coil 5
It is stored in a constant temperature bath 6 having. Further, a double glass see-through portion 7 is provided on the side surface of the constant temperature bath 6 so that it can be seen from the outside. Dry hot air is passed through the space portion 8 of the see-through portion 7 so as to prevent clouding due to condensation on the glass surface. The constant temperature bath 6 is attached to measure the characteristics of the sample at low temperature, and is not necessarily required to measure the characteristics under normal temperature conditions.

Two TV cameras 10 and 11 are installed as scanning devices on the outer side of the see-through portion 7 so as to face the inner pulling mechanism. Each camera processes an electric signal detected as shown in FIGS. 2A and 2B by the video circuit 14 and inputs it to the central processing unit 9. Also, this video circuit
The output signal processed by 14 can be monitored by the monitor TV 15.

One of the two cameras, the TV camera 11 is installed so as to face the entire tensile deformation area (large deformation area) until the test piece S breaks, and mainly detects the high elongation area of the test piece S. I am doing it. In this example, this TV
As the camera 11, a normal camera having 512 effective scanning lines is used.

On the other hand, the other TV camera 10 is limited in its entire field of view to the small deformation area in the initial stage of tension, and mainly detects the low elongation area of the test piece S. Moreover, the number of effective scanning lines is larger than that of the TV camera 11, and in this embodiment, 1024 lines are used. Since the number of effective scanning lines is increased and the entire field of view is limited to the small deformation area as described above, even a minute displacement can be read with high accuracy. In this case, if a zoom lens is attached to the TV camera 10 if necessary, it is possible to perform more accurate reading.

For example, a normal tensile test piece according to JIS No. 3 is used as the test piece S, and this test piece is pulled and the distance between the initial marked lines Q and Q is 20 m.
It is assumed that m is extended by 25% to 25 mm. Then, the displacement that can be read by the TV camera 10 is extremely accurate up to 25 mm / 1024 lines = 0.024 mm / line.

The two TV cameras 10 and 11 mentioned above are, in accordance with a command from the central processing unit 9, the former TV camera 10 in the low extension region at the start of the tensile test.
Scans, and then, when the test piece S exceeds the preset stretch ratio and extends to the high stretch region, the operation of the camera is switched and the latter TV camera 11 scans. The central processing unit 9 also controls the motor control unit 13 to change the pulling speed of the lower chuck 1b. Then, the speed is set low in the low expansion region, but when the high expansion region exceeds a preset expansion ratio, the normal speed is switched to a higher normal speed.

The result of the tensile property of the test piece measured by such an operation is output from the central processing unit 9 to the printer 16.
Reference numeral 17 is a keyboard for inputting data required for measurement.

As described above, the tensile test device for the rubber-like sample is equipped with at least two scanning devices, one of which is a high-precision extensometer exclusively for the low elongation region, and the other one is a normal extensometer. The scanning device is automatically switched from the high-precision extensometer to the normal extensometer when the test piece extends to a preset elongation rate. Therefore, it is possible to accurately read the elongation rate from the start of tensioning to cutting of the test piece, and particularly the elongation rate (0.2 to 20%) in the low elongation region to an accuracy of ± 0.2%. Also,
The elongation rate (20 to 600%) in the normal area can be measured with an accuracy of ± 1%.

When the tensile speed is switched at a preset elongation rate as in the above example, the low elongation modulus is measured in the low speed low elongation region, and then the high elongation modulus is measured in the normal speed high elongation region. You can Therefore, it becomes possible to simultaneously measure a plurality of tensile properties in one test.

〔The invention's effect〕

As described above, the tensile test device of the rubber-like sample of the present invention,
An electrical tester that scans the deformation of the measurement mark with a scanning device while deforming a rubber-like test piece with a measurement mark having different ground color and optical characteristics by applying a tensile load in the longitudinal direction, and outputs it according to the difference in optical characteristics. In a device for measuring the tensile properties of the test piece from a signal, the scanning device is composed of either a non-contact type television camera, a line sensor camera, or a laser scanner camera,
As the scanning device, a scanning device having a large deformation area of the test piece as a full field of view, and a scanning device of the large deformation area having a small deformation area of the test piece as a full field of view have an effective scan in a television camera. At least with a scanning device that has more than the number of lines, more than the number of effective pixels in a line sensor camera, or faster than its vibration speed in a laser scanner camera to improve measurement accuracy. Since the two scanners are provided side by side and the at least two scanners can be switched, the following excellent effects can be obtained.

That is, as the scanning device, at least two scanning devices having a large deformation area of the test piece as the entire field of view and a scanning device having the small deformation area of the test piece as the entire field of view are arranged side by side to perform switching operation. The scanning device in the small deformation area can reliably track the minute expansion deformation, and the scanning device in the large deformation area can reliably track the large expansion deformation. It is possible to measure at the same time, as a result, it becomes possible to efficiently and easily measure a plurality of tensile properties at each elongation,
In particular, it is extremely useful in the analysis of rubber properties having completely different viscoelastic behavior.

Further, a scanning device having a small deformation area as the entire field of view, the number of effective scanning lines in a television camera, the number of effective pixels in a line sensor camera, the number is larger than that used in the large deformation area, Or, in the laser scanner camera, because the vibration speed is made faster than that used in the large deformation area, the measurement accuracy is improved,
It is possible to accurately measure even elongation deformation of a minute rubber-like sample, and to obtain more reliable tensile properties.

Further, since the scanning device is composed of a non-contact type television camera, a line sensor camera, or a laser scanner camera, by increasing the number of effective scanning lines of the television camera or the number of effective pixels of the line sensor camera, Alternatively, by increasing the vibration speed of the laser scanner camera, it is possible to measure minute extensional deformation of the test piece with high accuracy, and it is possible to easily track the change in extension of the test piece that extends at high speed. Since the position can be fixed and used, the device can be made simpler and less expensive than the system in which the scanning device is moved.

Also, since the measurement is performed in a non-contact manner, it is possible to put the test piece in a constant temperature bath and measure it under various environments from high temperature to low temperature. It is extremely effective in simulating the environment described above, and the work of attaching and detaching the test piece for each measurement can be easily performed without disturbing the scanning device.

In addition to the above configuration, the tensile speed of the test piece is variable, and the at least 2
By configuring the scanning devices of the table to be switchable, it becomes possible to perform the measurement and analysis of the rubber showing the viscoelastic behavior of the rubber in each region with high efficiency due to the difference in the extension speed. By satisfying the requirements, it is possible to measure a physical test of a rubber having viscoelastically complicated and delicate properties with high efficiency and little variation.

Furthermore, the tensile speed of the test piece is reduced to a low speed in the small deformation area,
By making it possible to shift the speed in the large deformation region to a speed faster than that in the small deformation region, the measurement and analysis of rubber can be performed with higher efficiency.

[Brief description of drawings]

FIG. 1 is a schematic view of a tensile test apparatus for rubber-like samples according to an embodiment of the present invention, and FIGS. 2A, 3B and 3A, B, C are tensile tests for rubber-like samples using a scanning device, respectively. It is a principle explanatory view of a device. 1a …… Upper chuck, 1b …… Lower chuck, 9 …… Central processing unit, 10 …… (small deformation area is the whole field of view) TV camera, 11 …… (Large deformation area is the whole field of view) TV camera ,14
…… Image circuit, S, S ′ …… Test piece, Q …… Mark line (measurement mark), Q ′ …… Marking area (measurement mark).

Claims (3)

[Claims] 1. A rubber-shaped test piece provided with a measurement mark having different ground color and optical characteristics is deformed by applying a tensile load in the longitudinal direction, and the deformation of the measurement mark is scanned by a scanning device,
In the device for measuring the tensile properties of the test piece from the electrical signal output by the difference in optical properties, the scanning device is composed of either a non-contact type television camera, a line sensor camera, or a laser scanner camera, As the scanning device, a scanning device having a large deformation area of the test piece as a full field of view, and a scanning device of the large deformation area having a small deformation area of the test piece as a full field of view have an effective scan in a television camera. At least with a scanning device that has more than the number of lines, more than the number of effective pixels in a line sensor camera, or faster than its vibration speed in a laser scanner camera to improve measurement accuracy. With two units
A tensile test device for a rubber-like sample, wherein the at least two scanning devices are switchable. 2. A rubber-shaped test piece provided with a measurement mark having different ground color and optical characteristics is deformed by applying a tensile load in the longitudinal direction, and the deformation of the measurement mark is scanned by a scanning device,
In the device for measuring the tensile properties of the test piece from the electrical signal output by the difference in optical properties, the scanning device is composed of either a non-contact type television camera, a line sensor camera, or a laser scanner camera, As the scanning device, a scanning device having a large deformation area of the test piece as a full field of view, and a scanning device of the large deformation area having a small deformation area of the test piece as a full field of view have an effective scan in a television camera. At least with a scanning device that has more than the number of lines, more than the number of effective pixels in a line sensor camera, or faster than its vibration speed in a laser scanner camera to improve measurement accuracy. With two units
A tensile test device for a rubber-like sample, wherein the tensile speed of the test piece is variable, and the at least two scanning devices can be switched in conjunction with the tensile speed. 3. A rubber-shaped test piece provided with measurement marks having different ground color and optical characteristics is deformed by applying a tensile load in the longitudinal direction, and the deformation of the measurement marks is scanned by a scanning device,
In the device for measuring the tensile properties of the test piece from the electrical signal output by the difference in optical properties, the scanning device is composed of either a non-contact type television camera, a line sensor camera, or a laser scanner camera, As the scanning device, a scanning device having a large deformation area of the test piece as a whole field of view, and a scanning device of the large deformation area having a small deformation area of the test piece as a whole field of view are effectively scanned in a television camera. At least with a scanning device that has more than the number of lines, more than the number of effective pixels in a line sensor camera, or faster than its vibration speed in a laser scanner camera to improve measurement accuracy. With two units
The tensile speed of the test piece can be changed to a low speed in the small deformation area and a speed higher than the small deformation area in the large deformation area.
A rubber-like sample tensile test device characterized in that the scanning device of the table can be switched.