JPH11132731A - Video type noncontact extensometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To record the deformation state of a specimen with a relatively simple device structure without requiring troublesome work by recording the image data of the specimen at the set timing in relation with the elongation and load data at that time. SOLUTION: The image pickup signal of a specimen W by a camera 1 is A/D-converted 2 and temporarily stored in the RAM 31 of a controller 3. The controller 3 discriminates reticle marks M1, M2 put on the specimen W from the image data of the specimen W in the RAM 31, calculates the momentary shift quantities of the reticle marks M1, M2 from the momentary position information, calculates the momentary elongation between the reticles of the specimen W from the difference and stores it in an external memory device 4 in sequence. The controller of a material tester 10 is connected to the controller 3, and the momentary measured data of the tensile load to the specimen W by a load sensor such as a load cell are transmitted and stored in the external memory device 4. The images of the specimen W can be recorded with little memory capacity in relation with the elongation and load data at that time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video non-contact elongation measuring non-contact elongation between marked lines of a test piece using image data obtained by imaging the test piece with a camera. About the total.

[0002]

2. Description of the Related Art For example, a video non-contact extensometer is known as an extensometer for measuring the elongation of a test piece in a material test without contact. In a video non-contact extensometer, two mark positions are recognized from an image signal of a test piece by a camera, and the inter-mark elongation of the test piece is measured from the movement amount of each mark.

[0003] In the material test, the state of deformation of the test piece during the test can be important information.
Materials such as plastic tend to locally elongate when plastic deformation starts, and spread throughout. This phenomenon is called necking, but there is a difference in the load-elongation curve between when it starts between marked lines and when it does not. In addition, it is necessary to record as a result whether the location of the break is between or outside the marked lines.

Conventionally, when information on the state of such a deformation of a test piece is required, it is a fact that a person to be measured records the information in sentences or the like. It becomes accurate information and can be important information when analyzing after measurement.

In order to record the state of deformation of such a test piece during the test as image information, a method of attaching a video camera to a tester and recording an image of the test piece on a video tape is generally considered.

When a video non-contact extensometer is used, it is conceivable that image data obtained during the test is stored in a memory without being discarded.

[0007]

However, of the above methods, the method of recording the test piece image information on a video tape is based on the enormous amount of images recorded after the test, and If you try to match the elongation and load data, it is necessary to set common parameters such as the elapsed time from the start of the test in advance, and use the parameters as indexes to compare the two. There is a problem that is.

Further, when a video non-contact extensometer is used, storing all the image data in a memory consumes a huge memory capacity, and the device configuration becomes large. Not realistic.

The present invention has been made in view of such circumstances, and records the state of deformation of a test piece as image data with a relatively simple apparatus configuration and without complicated work. It is another object of the present invention to provide a video-type non-contact extensometer capable of taking correspondence with elongation and load data.

[0010]

In order to achieve the above object, a video non-contact extensometer of the present invention provides an image obtained by imaging a test piece marked with two mark marks with a camera. In a video-based non-video non-contact extensometer that uses data to measure the elongation between mark marks on a test piece, the image data of the test piece is associated with the elongation and load data at that time at a set timing. It is characterized by having means for storing the information.

Here, in the present invention, the set timing refers to, for example, an elapsed time after the start of the test, or a desired time such as a maximum load area in the load-elongation curve of the test piece, immediately before the fracture, or immediately after the fracture. In addition to timings set in advance, such as a point of arrival at a singular point or a singular region, real-time timings set by pressing a function key during a test, for example, are also included.

In the present invention, utilizing the image data collection function of a test piece inherently provided in a video type non-contact extensometer,
The image data of the test specimen during the test is stored.
By storing only the image data at the set point in time, in association with the elongation and load data, instead of storing all the image data, image data representing the state of deformation of the test specimen with a small memory capacity Can be stored in association with the elongation and load data.

The deformation information of the test piece is not particularly important during the entire test period, but specific deformation information such as the presence or absence of the necking phenomenon and the position of the break point has an important meaning as described above. Therefore, if image data is captured at a timing when a required image is obtained, the intended purpose can be achieved.

[0014]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

The imaging signal of the test piece W by the camera 1 is A
After being digitized by the -D converter 2, it is temporarily stored in the RAM 31 of the control unit 3 mainly composed of a computer. The control unit 3 identifies the positions of the two mark marks M1 and M2 attached to the test piece W from the image data of the test piece in the RAM 31 by a known method, and calculates the instantaneous position information. , Each mark mark M1, M2
Are calculated, and the instantaneous elongation between the marked lines of the test piece W is calculated from the difference between the respective amounts of movement. The measurement data of the instantaneous elongation is sequentially stored in the external storage device 4.

The control section 3 is connected to a control section of a material testing machine 10 for applying a tensile load to the test piece W. The control section 3 is connected to the test piece W by a load sensor such as a load cell incorporated in the material testing machine 10 every moment. The measurement data of the tensile load is transmitted. The measurement data of the instantaneous load is stored in the external storage device 4 in the form of a pair with the measurement data of the elongation.

An area for storing the latest several tens of frames of image data is set in the RAM 31 of the control unit 3, and each time one frame of image data is newly acquired, the image data is used for measurement of elongation. However, the oldest image data in the RAM 31 is discarded without discarding the latest image data.

A keyboard 5 for inputting various commands and conditions is also connected to the control unit 3, and the timing for recording image data can be set by the keyboard 5. This timing may be, for example, immediately before the start of the test based on a synchronization signal with the material testing machine 10, the elapsed time after the start of the test, or, as described later, the load obtained from the elongation-load data stored in the external storage device 4. Any singular point on the elongation curve can be used.

Each time the timing set by the keyboard 5 arrives, the control unit 3 deletes one frame of the image data stored in the RAM 31 together with the elongation and load measurement data. The data is stored in the external storage device 4 as a set.

Each data stored in the external storage device 4 is
The control unit 3 graphically displays the load-elongation curve in the form of a load-elongation curve and graphically displays the data on the display unit 6, and displays the image data of the test piece W taken in association with the elongation and the load data by a request command from the keyboard 5. I can do it.

FIG. 2 is a diagram for explaining an example of the timing of capturing the image data of the test piece W using a load-elongation curve. FIG. 3 is a diagram illustrating the image data of the test piece W captured at each image capturing timing. It is explanatory drawing of the example of.

In this example, the image data was obtained at six timings: A immediately before the start of the test, B in the elastic region, a point C near the maximum load, a point D where necking occurred, E before the fracture, and F immediately after the fracture. Is taking in.

In each of these timings, immediately before the start of the test A, image data can be taken in based on the synchronization signal from the material tester 10. In addition, since the duration of the elastic region is known in advance for some materials, for example, the point in the elastic region B can be set to any time after the start of the test until the duration elapses.

On the other hand, at the point C near the maximum load, the point D where necking occurs, the point E immediately before the fracture, and the point F immediately after the fracture, a time lag occurs between the test pieces. As a method for collecting these image data, for example, the following method can be adopted.

Using the already collected momentary elongation and load data, the control unit 3 sequentially calculates a load-elongation curve during the test to find that the maximum load has been reached, necking has occurred, or breakage has occurred. Recognize what has happened in near real time. As described above, the RAM 31 temporarily stores the image data for the latest several tens of frames as described above.
Since the corresponding image data should be stored in the RAM 31, the corresponding image data may be transferred to the external storage device 4 and stored together with the corresponding load and elongation data.

After the image data of the test piece W is stored at a predetermined timing as described above, the display 6 displays, for example, as shown in FIG. It is preferable because the situation of the deformation in becomes clear. That is, in this example, a display area 61 of the load-elongation curve and a display area 62 of the image data of the test piece W are set on the display 6, and the mark m representing the image data collection timing is set on the load-elongation curve. Is attached. By clicking, for example, an arbitrary one of these marks m, the corresponding image data is called up and displayed in the area 62. In addition, in the display area 62 of the image data, the load value 62b and the elongation value 62c at the time of capturing the image data are displayed together with the image data 62a.
Is also displayed.

In the embodiment described above, the timing at which the image data is taken in includes the singular point of the load-elongation curve. However, the present invention is not limited to this.
For example, image data may be fetched immediately before and immediately after the start of the test and at a certain interval between them.

Further, in the present invention, the image data fetch timing is set in advance as described above, and a function key for image fetch is set on the keyboard, and the key is operated. It is also possible to set in real time during the test, and it is also possible to adopt a configuration having both the function of setting the capture timing in real time and the function of setting the image capture timing in advance. Of course, when setting the image data capturing timing in real time, it goes without saying that the image data at the time of operating the key is stored in a state combined with the elongation and load data at that time.

[0029]

As described above, according to the present invention, only the image data at an arbitrarily set timing out of the image data of the test specimen necessarily taken in the video type non-contact extensometer is obtained. Because it is configured to be stored in association with the elongation and load data at the time, the image of the test piece at that time can be stored under a simple device configuration with a small storage capacity and without any troublesome work. It is possible to record the data in association with the elongation and load data, and it is possible to easily understand the load-elongation curve of the test piece and the deformation state under which the test proceeded.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a timing of capturing image data of a test piece W according to an embodiment of the present invention, using a load-elongation curve.

3 is an explanatory diagram of an example of image data of a test piece W obtained at each image capture timing in FIG.

FIG. 4 is an explanatory diagram of an example of display contents on the display 6 according to the embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 camera 2 A / D converter 3 control unit 31 RAM 4 external storage device 5 keyboard 6 display W test piece M mark mark

Claims (1)

[Claims] 1. An image pickup device comprising: a test piece having two mark marks attached thereto; and an image data obtained by imaging the test piece with a camera. A video non-contact extensometer for measuring elongation, comprising: means for storing, at a set timing, image data of a test piece in association with elongation and load data at that time. Contact extensometer.