JPH0739936B2 - Test piece elongation measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is used for conducting tensile tests and other material tests on transparent test pieces such as nylon, vinylon, and film. Elongation measuring device.

(Prior Art and its Problems) There are various types of test piece elongation measuring devices, which are roughly classified into two types, a contact type and a non-contact type. Of these, the contact method is a method in which the elongation of the test piece is electrically detected by directly contacting the contact line of the elongation measuring device with the marked line or the marked point attached to the test piece. However, in this method, an unnecessary force due to the contact of the contact piece acts on the test piece, so that an error occurs in the relationship between the tensile force and the elongation, which makes it impossible to perform highly accurate measurement.

On the other hand, the non-contact method is a method of projecting light on a test piece and observing the reflected light, but also in this case, there is a drawback that there is a problem in accuracy.

(Object of the Invention) The present invention is intended to overcome the above-mentioned drawbacks, and in measuring the elongation of a transparent test piece, a non-contact and highly accurate elongation measurement device for the test piece can be performed. In order to achieve the above-mentioned object, in the elongation measuring device for a test piece according to the present invention, a plurality of opaque markers are provided on the surface of the test piece having transparency. Assuming that a line is provided, a light source and a light projecting means formed of an optical fiber for transmitting light from the light source and projecting light onto the marked line of the test piece, and the test piece integrated with the light projecting means Light receiving means having a charge-coupled element that is placed opposite to each other and receives light that has passed through the marked line of the test piece from the optical fiber, and the relative relationship between the charge-coupled device of the light-receiving means and the marked line in a predetermined state. Based on the positional relationship A reference position setting means for setting a predetermined position on the marked line as a reference, and a movement amount of the reference position caused by extension of the test piece based on an output from the charge coupled device and a setting output of the reference position setting means. Of the reference position movement amount detecting means, the light receiving means moving means for moving the light receiving means according to the detection output of the reference position movement amount detecting means, following the movement of the reference position, and the light receiving means of the light receiving means. A plurality of pairs of light receiving means for detecting the movement amount and movement amount detecting means,
The reference position movement amount detecting means is configured to detect a change in the width of the marked line caused by the extension of the test piece by the output from the charge coupled device together with the movement amount of the reference position.

(Embodiment) FIG. 1 is a schematic side view of a test piece elongation measuring apparatus according to an embodiment of the present invention, and FIG. 2 is a periphery of a projector 13a and a light receiver 14a shown in FIG. FIG. The mechanical structure of this embodiment will be described below with reference to these drawings. It should be noted that other projectors 13b and receivers 14b in FIG.
Also has a configuration similar to that shown in FIG.

The elongation measuring device 1 in this embodiment is used for measuring the elongation of a transparent test piece 2 such as nylon or vinylon, and the test piece 2 is provided in a tensile test device (not shown). The chucks 3a and 3b are held by the chucks 3a and 3b, and the pulling force applied through the chucks 3a and 3b pulls the chucks 3a and 3b downward.
The elongation measuring device 1 is supported by a supporting rod 5 fixed to the yoke 4 of the tensile testing device. On the lower surface of the upper end of the support rod 5, two servo motors 6a, 6
b (servo motor 6b is located on the opposite side of servo motor 6a) is provided, and each servo motor 6a, 6b is
The screw rods 7a and 7b are connected to each other. The lower ends of the screw rods 7a and 7b extending downward in parallel to each other are encoders 8a and 8b provided on the lower end portion of the support rod 5 (the encoder 8a is not shown in FIG. 1). The encoders 8a and 8b are connected to the encoders 8a and 8b, respectively, and their rotation amounts are detected.

Further, nuts 9a and 9b are screwed into the screw rods 7a and 7b, respectively, and these nuts 9a and 9b move in the vertical direction of the drawing in accordance with the rotation of the screw rods 7a and 7b. These nuts 9a, 9
Fixed to b is a light projector 13a, 13b holding one-dimensionally arranged light emitting end portions 12a, 12b of optical fiber bundles 11a, 11b for transmitting light from a light source 10 (FIG. 2). There is.

Further, light receivers 14a, 14b for receiving the light L from the light projectors 13a, 13b are provided facing the light projecting surfaces of the light projectors 13a, 13b. The light receivers 14a and 14b include charge-coupled devices (hereinafter, referred to as CCDs) arranged in the vertical direction of the drawing,
Light is received by the CCD, and the light receiving portions 14a, 14b and the light projectors 13a, 13b are connected by connecting members 15a, 15b, respectively. However, in FIG. 2, for the purpose of illustration, the connecting member 15a is shown as a separated positional relationship. The light projector 13a and the light receiver 14a are provided in a positional relationship of sandwiching the test piece 2,
Moreover, the light projector 13b and the light receiver 14b are similarly provided in a positional relationship of sandwiching the test piece 2.

On the other hand, the test piece 2 is provided with a first opaque marking line 16a (and a second opaque marking line (not shown) present below) as shown in FIG. Therefore, the projector 13a,
The first marked line is provided between each of 13b and the light receivers 14a, 14b.
In the state where 16a and the second marking line are located, a part of the light from the projectors 13a and 13b is blocked by the first marking line 16a and the second marking line. The positions where the first marked line 16a and the second marked line are present are detected as the light receiving outputs of the light receivers 14a and 14b.
The mutual positional relationship among the light projector 13a, the light receiver 14b and the first marked line 16a in such a state is shown in FIG. 3 as a schematic front view.

Next, the electrical structure and operation of this embodiment will be described with reference to FIG. Although FIG. 4 shows only the electrical configuration related to the upper projector 13a and the light receiver 14a in FIG. 1, the electrical configuration and operation related to the lower projector 13b and the light receiver 14b are also shown in FIG. This is the same, and duplicate description will be omitted.
In FIG. 4, the light L emitted from the projector 13a
Is passed through the test piece 2 and the photodetector 14 shown in FIGS.
It is incident on CCD17a included in a. As described above, since the test piece 2 has the opaque first marked line 16a,
The light emitter 13a and the light receiver are arranged so that the first marked line 16a is located between the light emitter 13a and the light receiver 14a (hence the CCD 17a).
If the vertical positioning with respect to 14a is performed, the light incident on the CCD 17a becomes light having a shadow in the portion where the first marked line 16a exists. Therefore, the light reception output transferred from the CCD 17a by the transfer clock from the clock pulse generator 18 is a pulse signal train in which the level is changed only by the portion corresponding to the vertical width of the first marked line 16a. The received light output is amplified by the amplifier 19, and then input to the comparator 20 together with the threshold value signal output from the threshold value generator 21.

The threshold value signal is a signal having a threshold value level V ₀ as shown in FIGS. 5 (a) and 5 (b), and the comparator 20 compares the threshold value signal with the light reception output. , The counter of the next stage only the received light output pulse having a threshold value level V ₀ or higher
Output to 22. The counter 22 counts the pulses thus input, and the count number reflects the width of the first marked line 16a. Therefore, the first marked line when the test piece 2 is stretched by the tensile tester
The change in the width of 16a is obtained as the output of the counter 22, and this data is also output to the recording device 23, and is recorded in the recording device 23 as one of the elongation measurement data.

By the way, when measuring the elongation of the test piece 2,
It is necessary to know the displacement of the first marked line 16a according to the elongation of the. According to the present invention, the light receiver 14a is moved in accordance with the displacement (movement amount) of the first gauge line 16a, and the displacement of the first mark line 16a is known from the movement amount of the light receiver 14a. However, as described above, since the first marked line 16a itself has a width, the width thereof expands according to the elongation of the test piece. Therefore, there is a problem as to which position of the width of the first marked line 16a is used as the reference for measuring the displacement amount. In particular, if the width of the first marked line 16a becomes wider, its opacity becomes weaker. Therefore, if the above-mentioned threshold level V ₀ is set too large, it will correspond to the first marked line 16a at a large elongation. The light reception output pulse is below this threshold and the first marked line 16
Since the observation of a itself is not possible, the above threshold level V ₀
Should be small to some extent. For this reason,
The number of received light output pulses having a threshold value level V ₀ or higher increases, and the detection width of the first marked line 16a also increases,
The setting of the reference position becomes more important.

In consideration of such circumstances, the circuit of FIG. 4 is provided with a base point setting device 25 as a reference position setting means. The base point setting device 25 observes the received light output in a state before the test piece 2 is pulled, and as shown in FIG. 5 (a), among the pulses having a threshold value level V ₀ or higher, This is a circuit that specifies from which unit element of the many unit elements included in the CCD 17a the last input pulse is input, and stores and sets the unit element number n.
However, in this embodiment, assuming that the light reception output from the CCD 17a is transferred in order from the unit element located in the upper part of FIG. 1 or 2, as described above, the last input pulse is dealt with. That is, the unit element corresponding to the lower end (reference position) of the width of the first marked line 16a is set as the base point before pulling, but it corresponds to the upper end or the center of the width of the first marked line 16a. It is also possible to set the unit element to be the base point. The base point set on the width of the first marked line 16a,
The unit element number in the CCD 17a can be used in this way because the CCD 17a moves as the first marked line 16a is displaced, as will be described later.

Next, description will be made regarding the configuration and operation of the stage subsequent to the counter 22 shown in FIG. As described above, the counter 22 counts the pulse output from the comparator 20.
At the same time, the transfer clock from the clock pulse generator 18 is input, and by referring to this, the last input pulse of the pulses given from the comparator 20 is transferred from which unit element in the CCD 17a. Identify what has been done. Then, the data indicating the unit element number is output to the displacement detector 24. In addition, the unit element number n corresponding to the base point is input as data from the base point setting device 25 to the displacement detector 24. The displacement detector 24 compares the number n with the number given by the counter 22, detects the amount of movement of the base point on the first marked line 16a, and servos the signal according to this amount of movement. It is given to the motor drive system 26. Then, the servo motor drive system 26 rotationally drives the servo motor 6a according to the input signal.

Therefore, for example, before pulling, the received light output as shown in FIG. 5 (a) remains as it is, and the number data given from the counter 22 to the displacement detector 24 also remains as n. The output of 24 becomes a zero signal, and the servomotor 6a does not rotate. However, when the test piece 2 is stretched by pulling, as shown in FIG.
Since the unit element number corresponding to the last pulse among pulses having a level of V ₀ or higher changes to (n + m),
A signal corresponding to the difference m is output from the displacement detector 24, and the servo motor 6a rotates. Then, the mechanism shown in FIG. 1 rotates the screw rod 7a to move the nut 9a downward,
The light projector 13a and the light receiver 14a also move downward about it. The nth unit element of the CCD 17a is the first marked line 16
When it comes to face the lower end of a, the output of the counter 22 indicates the number n, the output of the displacement detector 24 becomes zero output, the rotation of the servomotor 6a stops, and therefore the movement of the light receiver 14a and the like. Stops.

In this way, the movement amount of the light receiver 14a follows the movement of the lower end of the first marked line 16a, and the encoder 8a encodes the rotation amount of the screw rod 7a corresponding to the movement amount of the light receiver 14a. If it is taken into the recording device 23 and recorded, the first
The amount of elongation at the lower end of the marked line 16a of is accurately measured. Then, in the recording device 23, data 3 representing each of the moving amount of the second marked line and the changing amount of the width thereof is recorded.
0 and 31 are taken in from the same circuit as in FIG. 5, and the first marked line 16
By recording the difference in the amount of movement of a and the second marked line, it is possible to measure the amount of elongation between these two marked lines. Further, since the light receiving means is moved following the base point on the reference line, the reference line does not deviate from the light receiving range of the light receiving means even if there is a large elongation.

In addition, in the above-mentioned embodiment, the structure including the optical fiber is adopted as the light projecting means, and by doing so, the elongation measurement can be performed without applying the heat from the light source to the test piece 2, It is possible to prevent adverse effects such as thermal expansion. The test piece is not limited to a highly transparent one, but may be a semi-transparent one. In this case, it is desirable to project strong light such as laser light.

In the above embodiment, two sets of each of the above-mentioned means are provided, but it is also possible to provide three or more marked lines and three or more sets of each of the above-mentioned means to measure the relative movement amount between the marked lines. Is.

Further, as disclosed in Japanese Patent Publication No. 59-25442,
If the above-mentioned threshold value is changed with time and the received light output pulse having a level equal to or higher than the threshold value is counted over a plurality of CCD scans and the average of the count values is obtained, the change in the marked line width is further improved. It can also be measured accurately.

(Effects of the Invention) As described above, according to the present invention, since the light receiving means is moved in accordance with the reference position on the marked line and the extension is detected by detecting the amount of movement, transparency is improved. Non-contact and highly accurate elongation measurement can be performed on a test piece having

[Brief description of drawings]

FIG. 1 is a schematic side view showing the mechanical structure of a test piece elongation measuring apparatus according to an embodiment of the present invention, and FIG. 2 is a perspective view showing the surroundings of a projector and a light receiver of the apparatus shown in FIG. Figure, third
FIG. 4 is a schematic diagram showing the positional relationship in the apparatus of FIG.
FIG. 5 is a block diagram showing a part of the electrical configuration of the apparatus of FIG. 1, and FIG. 5 is a diagram showing an example of the light receiving output of the CCD in the circuit of FIG. 1 ... Elongation measuring device, 2 ... Test piece, 6a, 6b ... Servo motor, 8a, 8b ... Encoder, 13a, 13b ... Emitter, 14a, 14b ... Photoreceiver, 16a. Line, 17a …… CCD, 21 …… Threshold value generator, 22 …… Counter, 24 …… Displacement detector,

Claims (1)

[Claims] 1. An apparatus for providing a plurality of opaque marked lines on the surface of a transparent test piece and measuring the elongation of the test piece by the marked lines, the device comprising a light source and light transmitted from the light source. Light projecting means comprising an optical fiber for projecting on the marked line of the test piece, and light which is integrated with this projecting means and is opposed to the test piece with the test piece sandwiched therebetween and which passes through the marked line of the test piece from the optical fiber. A light receiving means having a charge coupled device for receiving the light, and a reference position setting based on a relative position relationship between the charge coupled device of the light receiving means and the marked line in a predetermined state with a predetermined position on the marked line as a reference Means, reference position movement amount detecting means for detecting the movement amount of the reference position caused by the elongation of the test piece based on the output from the charge coupled device and the set output of the reference position setting means, and the reference position. Movement amount inspection A plurality of sets of light receiving means moving means for moving the light receiving means in accordance with the movement of the reference position based on the detection output of the means, and light receiving means moving amount detecting means for detecting the moving amount of the light receiving means, The reference position movement amount detecting means is configured to detect a change in the width of the marked line caused by the elongation of the test piece by the output from the charge coupled device together with the movement amount of the reference position. Piece elongation measuring device