JPS6111362B2 - - Google Patents

Description

Detailed Description of the Invention This invention uses an image sensor such as a CCD as a detector in the manufacturing process of wire rods such as wire ropes, so that the wire rod can remain online without stopping and can be operated without contact. The present invention relates to a wire diameter measuring device capable of measuring the diameter of the wire.

In general, when manufacturing wire rods such as wire ropes having a desired cross-sectional shape and diameter,
The work involves passing a wire base material through a tool (die) with a tapered hole and pulling it out in the axial direction, thereby reducing its cross-sectional area. Especially wire drawing work to produce wire rods with a diameter of several millimeters. In this case, as shown in FIG. 1, the wire preform 2 drawn out from the feed roller 1 is passed through a die 4, wound around a take-up roller 5, and pulled out to have a desired cross-sectional shape and diameter. This method is used to obtain the wire rod 3, and has the advantage that long wire rods can be processed at extremely high speeds (approximately 1.000 m/min).

By the way, in the above-mentioned wire rod manufacturing process, since the wire rod itself runs at high speed, there is a risk that the diameter of the wire rod may change due to abrasion or chipping of the die. In order to maintain this, it is necessary to constantly measure the diameter of the drawn wire. However, it is difficult to perform highly accurate measurements within limited dimensional tolerances while the wire is still running at high speed.
Conventionally, the machine has been stopped periodically and its dimensions have been measured by a contact method using calipers or gauges and by manual visual inspection.

However, it goes without saying that there are limits to measurement efficiency and accuracy, and in addition, there is a large proportion of lost time due to stopping the machine itself during measurement, which reduces the operating rate of the production line. As a result, the measurement method could not be fully adapted to the streamlined wire manufacturing process.

In view of the various points mentioned above, the present invention provides a device that has extremely high measurement accuracy compared to conventional measurement methods and that can measure wire diameter in a non-contact manner while remaining online. The purpose is to In other words, the device of the present invention is a device that measures the diameter of a wire rod that continuously runs linearly in a fixed direction, and the center of the wire rod coincides with the base line of the running line as a reference. a lens system having a depth of field set so that the image of the wire becomes blurred when the wire is shifted from the lens, a light source arranged on the opposite side of the lens system with respect to the wire to illuminate the wire, and a light receiving surface; an image sensor that scans a wire image projected onto the light-receiving surface via a system in the radial direction at a constant period, and outputs a video signal containing diameter data corresponding to the wire image; The time width of the portion of the video signal output from the image sensor that corresponds to the dark portion when the wire is at the base line is the same as the time width of the portion of the video signal output from the image sensor that corresponds to the dark portion when the wire is at the base line position. The level of the video signal from the image sensor is compared for each scan with a slice level set so as not to be larger than the time width of the corresponding portion, and the level of the video signal is determined according to the time width below the slice level. and a comparison means for outputting the diameter data of the wire image using the comparison means, and a maximum value included in the diameter data for multiple scans obtained by the comparison means is held at regular time intervals, and the maximum value is outputted for the multiple scans. and a circuit that outputs the diameter data as a measured value.

Hereinafter, one embodiment of the present invention will be described in detail based on the drawings.

First, the wire diameter measuring device of the present invention uses a solid-state image sensor (hereinafter simply referred to as an image sensor) such as a CCD (charge-coupled device) or a BBD (bucket brigade device) as a detector to obtain a side view or diameter image of the wire. As shown in FIGS. 1 and 2, a fluorescent lamp or the like is installed below the running wire 3 in the intermediate part near the die between the drawing stage by the die 4 and the winding stage by the take-up roller 5. A light source 6 is disposed above the light source 6, and a lens 7 with an extremely shallow depth of field and an image sensor 8 are disposed above the light source 6, and the image sensor 8 constantly monitors the diameter of the wire 3. At the same time, a dark image of the wire 3 is created by the light from the light source 6, and this image is formed and projected onto the light receiving surface of the image sensor 8 by the lens 7.

On the light-receiving surface of the image sensor 8, there are
A large number of pixels are arranged in a straight line so as to be orthogonal to the running direction, and therefore, each time the image sensor 8 scans, the edge of the wire 3 is scanned in the radial direction, and each pixel receives light. Video signals corresponding to the amount are sequentially output.

Here, it is basically desirable that the wire rod 3 travels in a straight line with its axis aligned with the base line P of the travel line, but in reality, the wire rod 3 depends on the tension and speed at the time of drawing. , travels while repeating vibrations at a constant period, which varies depending on the diameter of the wire rod 3. Therefore, the device of the present invention actively utilizes the vibration phenomenon of the wire rod 3, and the lens 7
The depth of field is set to be extremely shallow so that the axis of the wire 3 coincides with the base line P of the running line and its focus coincides. Therefore, if the axis of the running wire 3 deviates even slightly from the base line P of the running line, the image of the wire diameter will be greatly blurred, and the video signal for one scan output from the image sensor 8 will be blurred. will have the waveforms shown in b and c in FIG. 3, and will have the waveform shown in a in FIG. 3 only when the axis of the wire 3 and the base line P of the running line match.

The analog video signal that is photoelectrically converted and sent out from the image sensor 8 for each scan is converted into a bright/dark binary signal by a comparator 9 at a specific slice level set by a slice level setter 10, and then sent to a counter 11. The number of dark bits corresponding to the image of the wire diameter is counted every fixed scan by a signal from the synchronizing pulse generating circuit 12 which is input and synchronized with the scanning operation of the image sensor 8.
The slice level setter 10 has a function to automatically follow changes in the amount of light, and the slice level set by this means that the waveform shown in FIG. 3 is completely shaded. The level is set slightly higher (nearly 1/3 or less of the bright level) than the level when the bright level is set.

That is, as shown in Fig. 3, only within the dark level section below the slice level of each waveform, a synchronization pulse signal corresponding to the time length of that section is obtained, and the video signal for one scan is obtained. The number of pulses within the dark level section below the slice level is sequentially counted by the counter 11 as diameter data of the wire 3 in that scan. Therefore, only in the state of the waveform shown in a of the same figure, in other words, in a state in which the focus is aligned, the diameter data obtained is maximum and corresponds to the actual wire diameter, as shown in b and c of the same figure. In the state of the waveform shown in , that is, in the state where the focus is not matched, the entire image becomes largely blurred due to the light that wraps around the wire 3, and the edges develop sag, and the dark level is not lower than in the state where the focus is matched. , and the dark level section becomes shorter, so the diameter data obtained thereby becomes smaller than the actual wire diameter. Here, the counter 11 is configured to be reset for each scan by a signal from the synchronizing pulse generation circuit 12, and as a result, the diameter data of the wire image for each scan is sequentially transferred to the maximum value holding circuit. 13.

The wire diameter data sequentially inputted to the maximum holding circuit 13 are retained until the reset pulse generation timer circuit 14 obtains a reset pulse signal at a preset time interval. The image sensor 8 is configured to hold the maximum value, and during the periodic time for the timer circuit 14 to generate a pulse signal, the image sensor 8 is scanned multiple times at a constant cycle, and for each scan, the maximum value holding circuit 13 is Since the diameter data of the wire rod image is sequentially input to the , the diameter data held in the maximum value holding circuit 13 is updated sequentially when larger diameter data is input within the cycle time of the timer circuit 14. be done. And the above timer circuit 1
When the reset pulse signal from 4 is obtained, the timer circuit 14 itself is reset, and the maximum value of the diameter data for multiple scans within the time up to that time is determined as the measured value for the multiple scans.
At the same time, the maximum value holding circuit 13 is also reset to newly hold the maximum value for the next scan.

The cycle time of the timer circuit 14 is set according to the diameter of the wire or its running speed so that the axial center of the wire 3 running while vibrating matches the base line P of the running line, that is, it includes multiple vibration cycles of the wire 3. It is assumed that it has been set empirically in advance, etc.
In the case of this embodiment, the frequency of the wire 3 is approximately 20Hz,
The amplitude is set to approximately ±0.2 mm and is set to approximately 0.5 to 1 second.

On the other hand, the determination circuit 15 is configured to receive respective values of the maximum allowable dimension and minimum allowable dimension of the wire diameter preset in the setting device 16, and here the values are inputted from the maximum value holding circuit 13 mentioned above. It is determined whether the output diameter data of the wire is within the dimensional tolerance of the above-mentioned allowable limit dimensions, and as a result, if the diameter data deviates from the above-mentioned allowable limit dimensions, it is set as an abnormal alarm and, for example, spray The data is outputted to a device 17, and a marking indicating a diameter defect is applied to a portion of the running wire 3 where the diameter is abnormal.

As a result of such a configuration, the diameter of the wire rod 3 that continuously runs in a straight line in a certain direction is repeatedly measured every 0.5 to 1 second (approximately 17 m/once) while online, and the diameter is measured each time. It is determined whether or not there is a diameter defect.

As is clear from the above description, the wire rod diameter measuring device according to the present invention is a device for measuring the diameter of a wire rod that continuously runs linearly in a certain direction.
A lens system in which the depth of field is set so that the center of the wire coincides with the base line of the running line, and the image of the wire becomes blurred when the wire shifts from the base line of the running line; A light source disposed on the opposite side of the lens system to illuminate the wire, having a light receiving surface, scanning the wire image projected onto the light receiving surface via the lens system at a constant period in the radial direction; An image sensor that outputs a video signal including diameter data corresponding to the wire image, and a time width of a portion corresponding to a dark part of the video signal output from the image sensor when the wire is shifted from the base line. , a slice level set so that the time width is not greater than the time width of a portion corresponding to a dark area of the video signal output from the image sensor when the wire is at the base line position, and the video signal from the image sensor. a comparison means for comparing the level of each scan for each scan and outputting diameter data of the wire according to a time width in which the level of the video signal is equal to or lower than the slice level; and a plurality of scans obtained by the comparison means. It is equipped with a circuit that holds the maximum value included in the diameter data of the wire rod at regular intervals and outputs the maximum value as the measured value of the diameter data of the multiple scans. The diameter of the wire rod can be measured from the maximum data of the change in image length, and therefore the diameter of a continuously running wire rod can be measured online and with high accuracy without contact. The measurement efficiency can be significantly improved.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of the most common wire drawing (drawing) process, and FIG. 2 is a block diagram showing an example of the wire diameter measuring device according to the present invention.
FIG. 3 is an explanatory diagram showing the relationship between the position of the wire and the waveform of the video signal including its image. 3... Wire, 7... Lens, 8... Image sensor, 11... Counter, 13... Maximum value holding circuit, 15... Judgment circuit, P... Base line.

Claims (1)

[Claims] 1 A device that measures the diameter of a wire rod that runs continuously in a straight line in a fixed direction, with the center of the wire rod matching the base line of the running line as a reference, and when the wire deviates from the base line of the running line. A lens system having a depth of field set so that the image of the wire is blurred, a light source disposed on the opposite side of the lens system with respect to the wire to illuminate the wire, and a light-receiving surface. an image sensor that scans a wire image projected on a light-receiving surface in its radial direction at a constant cycle and outputs a video signal containing diameter data corresponding to the wire image; When the wire is at the baseline position, the time width of the portion of the video signal output from the image sensor that corresponds to the dark portion is equal to the time width of the portion of the video signal output from the image sensor that corresponds to the dark portion. The level of the video signal from the image sensor is compared for each scan with the slice level set so as not to become larger than the time width, and the wire rod image is determined according to the time width in which the level of the video signal is less than or equal to the slice level. a comparison means for outputting the diameter data of the plurality of scans, and a maximum value included in the diameter data of the plurality of scans obtained by the comparison means is held at regular intervals, and the maximum value is used as the diameter data of the plurality of scans. A wire diameter measuring device comprising: a circuit for outputting a measured value;