JP3299800B2 - Elongation measurement method in tensile test - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring elongation in a tensile test for measuring elongation of a material such as rubber, resin, fiber, etc., and more particularly to a method for correcting aberrations at both ends by a camera lens. The present invention relates to a method for measuring elongation in a tensile test capable of improving accuracy.

[0002]

2. Description of the Related Art Tensile strength of materials such as rubber, resin and fiber,
When measuring tensile properties such as elongation stress or elongation at break, hold both ends of a test piece made of the above material with chucks, move one of the chucks, pull the test piece, and apply elongation deformation. It is well known that the constructed tensile test apparatus is used. For example, when obtaining the elastic modulus at 100% elongation, elongation at break, and the like with such a tensile test apparatus, it is extremely important to more accurately measure the elongation of the material in terms of the accuracy of the tensile properties. .

Conventionally, a camera such as a vidicon camera and a computer having a central processing function are installed in the above-described tensile test apparatus, and a displaced image of a measurement reference line having different optical characteristics applied to a test piece is taken by the camera. The read signal is processed by a computer to measure the elongation of the test piece.

[0004]

However, since the elongation measuring method in the above-mentioned tensile test is a measurement using a camera, it is affected by aberrations caused by a lens used in the camera, so that both ends of the lens are not affected. , There is a problem that the measurement accuracy decreases. In addition, since the measurement up to now is hard processing, it is easily affected by noise, and if the marking line is cut or stretched and separated,
There was a problem that the measurement was poor. The purpose of the present invention is
It is an object of the present invention to provide an elongation measuring method in a tensile test that corrects aberrations at both ends of a lens to improve measurement accuracy.

[0005]

In order to achieve the above object, the present invention reads a scale of a standard plate with an image reading device which reads an image through a camera lens, and stores the scale read by a central memory via a frame memory. after I Captures the arithmetic processing unit, extension of and a tensile load was applied to the test piece
So, parallel the read by the image reading apparatus wherein the test specimen
The measurement unit having the two mark lines attached to is taken into the central processing unit via the frame memory, and the number of the mark lines is determined from the taken image data of the measurement unit ,
If the number of the marked lines is determined to be two, the position of the boundary line on one side
Calculate the positions of the two marked lines that have been averaged
The marked line was separated by elongation of the test piece and judged to be 3 or more.
If set, two with an interval greater than the minimum setting
Averaging the position of the boundary line on one side of the marked line
The position of the marked line is calculated, and the obtained positions of the two marked lines are obtained.
Is compared with the scale data of the standard plate taken into the central processing unit, the distance between the marked lines is calculated, and the elongation of the test piece is obtained.

[0006]

[0007]

According to the present invention, there is provided an image reading apparatus for determining the elongation between the marked lines of a test piece on the basis of the scale of a standard plate previously read from an image reading apparatus via a frame memory. Even if aberrations occur at both ends of the test piece due to the above lens, the elongation between the marked lines whose aberration has been corrected can be obtained from the scale data of the standard plate.

Further, by averaging the boundary line on one side of the marked line, even if the linearity or parallelism of the marked line of the test piece to which a tensile load is applied is lost, the measurement can be performed. The position of the marked line can be obtained accurately. Further, by setting the minimum distance between the marked lines, it is possible to accurately obtain the marked lines even if the marked lines of the test piece to which the tensile load is applied are separated.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram illustrating an example of a tensile tester used in the present invention, and FIG. 2 is a flowchart illustrating a method of measuring a tensile test by the tensile tester. In FIG. 1, 1a is an upper chuck for gripping the upper end of the test piece S, and 1b is a lower chuck for gripping the lower end of the test piece S. The test piece S has two measurement marks Q, Q for measurement marks of a color having a different optical property from the ground color of the test piece S on the measuring portion.
'Are parallel to each other.

In the vicinity of the test piece S, a standard plate P having graduations at equal intervals is provided. The standard plate P is used in measurement using a camera to improve the influence of aberration caused by a lens used in the camera. Therefore, the installation position of the standard plate P is determined via the camera lens arranged near the test piece S.
It is installed so as to be equal to the distance from the image reading device 2 such as a CCD camera for reading an image to the test piece S. If the image reading device 2 can swing, the standard plate P is not necessarily near the test piece S and is very good.

The upper chuck 1a is installed so as to be stationary at a fixed position, and the lower chuck 1b is movable. A load cell 3 for detecting a tensile load is connected to the lower chuck 1b. The tensile load detected by the load cell 3 is input to the central processing unit 6 (CPU) via the load cell amplifier 4 and the A / D converter 5.

A tensile load is applied to the test piece S by driving a drive motor 7 for pulling the lower chuck 1b downward, and the drive motor 7 includes a drive circuit 8 and an I / O
It is connected to the central processing unit 6 via an O (interface) 9. A frame memory 10 is connected to the image reading device 2 for measurement arranged near the test piece S,
The image of the test piece S read by the image reading device 2 is sent from the frame memory 10 to the central processing unit 6.

The central processing unit 6 has a memory unit for storing one frame of image data input to the frame memory 10 when the image reading unit 2 reads the scale of the standard plate P. Then, the distance between the marked lines Q and Q ′ for each frame of the test piece S read by the image reading device 2 is compared with (compared to) the scale data of the standard plate P stored in the memory unit. It is configured to calculate
There Ru.

Further, the central processing unit 6 outputs the marking lines Q and Q '.
Prior to the calculation of the distance, the positions of the upper and lower boundaries on the one side of the marking lines Q and Q 'are averaged to determine the positions of the read marking lines Q and Q'. And even more
The minimum distance between the reference lines Q and Q 'is set, and a value less than the minimum value is not determined to be a reference line. Also,
In the central processing unit 6, the elongation of the test piece S, the load cell 3
Calculates tensile properties such as modulus, elongation, and stress of the test piece S based on the tensile load signal sent from the
These values are output to a display unit or a recording unit such as a CRT 12, a printer 14 provided via a printer buffer 13, and an XY pen recorder 16 provided via a D / A converter 15. I have.

Reference numeral 17 denotes a program input unit for inputting a program card such as a RAM card, and 18 denotes illumination for the test piece S. Next, a method of measuring a tensile test by the above-described tensile test apparatus will be described with reference to FIGS. First, the test piece S is set on the upper chuck 1a and the lower chuck 1b (step), and the zero point of the load applied to the load cell 3 is corrected (step). Subsequently, as shown in FIG. 3, the scale m of the standard plate P is read by the image reading device 2,
The image data for the frame is stored in the memory unit of the central processing unit 6 as the absolute value of the frame line. That is, the frame memory 10 is obtained by the scale data of the standard plate P.
Is performed (step).

Next, the thickness and width of the test piece S and the marked lines Q and Q
Necessary data such as the distance between ′ is input from the input board 11 (step), and the data is taken into consideration in consideration of the influence of disturbance and the like.
Set the threshold level for value conversion (step). Then, measurement is started (step).
When the drive motor 7 operates, the lower chuck 1b moves downward, a tensile load is applied to the test piece S, and the test piece S elongates.
You. This tensile load value is detected by the load cell 3,
The data is input to the central processing unit 6 via the load cell amplifier 4 and the A / D converter 5. From the image reading device 2,
The measurement units of the test pieces S are sequentially input (for example, every 30 msec.) To the central processing unit 6 via the frame memory 10.

In the central processing unit 6, the input image data of the test piece S is binarized for each frame based on the set values described above, and the number of marked lines is calculated first. If it is determined that the number of the marking lines is two, the positions of the one-side boundary lines of the marking lines Q and Q 'are averaged to calculate the positions of the marking lines Q and Q'.
As shown in FIG. 4, even if the marked lines Q and Q 'of the test piece S to which the tensile load is applied become inclined, the positions X and X' of the marked lines Q and Q 'can be accurately determined by this averaging process. Can be obtained.

The marked lines Q and Q of the test piece S to which the tensile load is applied
Are separated and if it is determined that the number of marking lines is three or more, one of the upper or lower marking lines having an interval equal to or greater than the set minimum value is regarded as a normal marking line Q, Q '. Then, the positions X and X 'of the marked lines Q and Q' are determined in the same manner as described above. FIG.
Shows an example in which the upper marking line Q is separated into two marking lines Q _{1 and} Q ₂ , and two marking lines Q _{1 and} Q having a distance a greater than or equal to the set minimum value.
'Is selected as a regular mark. Thereby, even if the marked lines Q and Q ′ of the test piece S are separated, there is no adverse effect due to the separated marked lines.

When the positions X and X 'of the marking lines Q and Q' are calculated, the marking lines Q and Q 'are compared with the scale data of the standard plate P stored as the absolute values of the frame lines in the memory unit. The distance between them is calculated, and the elongation between the marked lines Q and Q 'is calculated (step). As described above, the scale m of the standard plate P is read in advance by the image reading device 2 and the elongation between the marked lines Q and Q ′ of the test piece S is obtained based on the read scale m data. Even if aberration occurs on both ends of the test piece S due to the lens of the apparatus 2, the scale data of the standard plate P is also taken in with the aberration, so that the reference lines Q and Q 'which are not affected by the lens aberration.
It is possible to obtain a stretch between them.

Subsequently, on the basis of the input data, the tensile load data from the load cell 3 and the calculated elongation data of the test piece S, the tensile properties such as modulus calculation, stress and elongation are calculated (step). The result is CRT12,
The data is output to a display unit or a recording unit of the printer 14, the XY pen recorder 16, or the like (step). As described above, according to the present invention, the scale m of the standard plate P is read by the image reading device 2, the read scale m is loaded into the central processing unit 6 via the frame memory 10, and then read by the image reading device 2. Two marked lines Q, Q of the test piece S
Is taken into the central processing unit 6 via the frame memory 10, and the distance between the marked lines Q and Q 'of the taken measurement unit is converted into the scale data of the standard plate P by the central processing unit 6. In order to obtain the elongation of the test piece S by performing a calculation in comparison, the lens of the image reading device 2 uses the test piece S
Even if aberration occurs at both ends of the mark, the marked lines Q and Q with high accuracy corrected for aberration by the scale data of the standard plate P
It is possible to calculate the elongation between '.

Also, by averaging the boundary line on one side of the marked lines Q and Q 'and setting the minimum value of the distance between the marked lines Q and Q', noise, defective marked lines of the test piece S, etc. It is possible to effectively prevent measurement failure due to the influence of. Further, by increasing the resolution of the image reading device 2 and the frame memory 10 and by providing a blur prevention process for preventing blur when the marked lines Q and Q 'of the test piece S to which a tensile load is further applied are blurred. Measurement accuracy can be further improved.

[0022]

As described above, according to the present invention, the elongation between the marked lines of the test piece is determined on the basis of the scale of the standard plate previously taken in from the image reading device via the frame memory. The aberration of the test piece caused by the above lens can be effectively corrected, and the measurement accuracy can be improved.

Further, by averaging the boundary line on one side of the marked line, even if the linearity or parallelism of the marked line of the test piece to which a tensile load is applied is lost, the measurement is performed. It is possible to accurately obtain the position of the marked lines, and by setting the minimum distance between the marked lines, two marked lines can be accurately detected even if the marked lines of the test piece subjected to tensile load are separated. In addition, it is possible to effectively prevent measurement failure due to the influence of noise, defective marking of the test piece, and the like.

[Brief description of the drawings]

FIG. 1 is an explanatory block diagram showing an example of a tensile test apparatus used in the present invention.

FIG. 2 is a flowchart illustrating a method of a tensile test by the tensile test device of FIG. 1;

FIG. 3 is an explanatory diagram illustrating reading of a standard plate by the image reading device of FIG. 1;

FIG. 4 is an explanatory diagram illustrating mark line averaging processing.

FIG. 5 is an explanatory diagram illustrating separation of a marked line.

[Explanation of symbols]

1a Upper chuck 1b Lower chuck 2 Image reading device 3 Load cell 6 Central processing unit 10 Frame memory P Standard plate Q, Q 'Marking line S Test piece

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G01N 3/00-3/62 G01B 11/16 JICST file (JOIS)

Claims (1)

(57) [Claims] In view <br/> image reading apparatus for reading an image through a 1. A camera lens reads the scale of the standard plate, after I Captures the central processing unit of the read memory via the frame memory , Stretched by applying tensile load to the test piece
Is allowed, flat of the test piece was read by the image reading apparatus
A measurement unit having two mark lines attached to a row is taken into the central processing unit via the frame memory, and the number of the mark lines is determined from the taken image data of the measurement unit.
If it is determined that the number of the marked lines is two, one of the boundary lines
Calculate the position of the two marked lines by averaging the positions of
And the marked lines are separated by extension of the test piece.
If it is judged above, there is an interval longer than the set minimum value
Averaging the position of the boundary line on one side of the two marked lines
The positions of the two markers are calculated, and the two markers obtained are obtained.
An elongation measurement method in a tensile test for calculating the elongation of the test piece by calculating the distance between the marked lines by comparing the position of the test piece with the scale data of the standard plate taken into the central processing unit .