JPS6312241B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for inspecting objects having the same cross-sectional shape in the longitudinal direction, such as wire bodies such as hoses and cables, for defects such as shape and cross-sectional unevenness.

Conventional methods for inspecting the shape of the striatum include a method in which narrow illumination is performed perpendicularly to the longitudinal direction of the striatum, and an elliptical mirror is used to detect the diffusely reflected light component at the defective part; A method of inspecting defects by bringing a thread or die into contact with the surface and detecting its displacement (Japanese Patent Application Laid-open No.
53-33064).

In the method of detecting diffusely reflected light, it is difficult to detect because the change in the diffusely reflected light component due to gentle unevenness is small. Furthermore, if there is a printed mark or the like on the surface of the striatal body that has a higher diffuse reflectance than the surface, there is a drawback that the printed mark may be erroneously detected as a defect.

On the other hand, in the method of bringing yarn or soybeans into contact, there is a high possibility that the surface will be damaged by contact, and if the moving speed of the filament becomes high, it is difficult to follow.

Furthermore, in the above two methods, the cross-sectional shape of the filament itself is not inspected, but the diffusely reflected light from it is detected, or the tensile force of the thread or die is detected. The disadvantage is that accurate shape inspection cannot be achieved.

On the other hand, there is the optical cutting method, and the conventional technology of this method includes its application to automatic orbit inspection (Japanese Patent Application Laid-Open No.
143358), in which the condition of the rails is automatically measured while the track inspection vehicle is running.

In this method, an object is inspected at regular time intervals by detecting and processing an optically sectioned image using a two-dimensional image sensor.

However, depending on the type of filament, it is necessary to inspect minute irregularities on the surface as well as changes in the cross-sectional shape of the filament, and for this purpose, inspection by sampling at fixed time intervals cannot be used.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide an apparatus that can inspect the shape and defects of a filament at high speed and with high precision.

The main point of the present invention is to project a slit-shaped light of uniform intensity and width from the periphery in a plane perpendicular to the central axis of the striatum in order to detect the cross-sectional shape and defects of the striatum. The point is that a light cutting method is adopted in which the image is detected from an oblique direction or a direction parallel to the central axis of the striatum.

In addition, in the present invention, in order to inspect the presence or absence of an abnormally shaped part at high speed, a light beam of a good product is placed on the real image plane of the light cutting detector that detects the slit image projected onto the surface of the striatum in the above light cutting method. This method uses an optical mask with a cut image printed on it, collects the light leaking from it, and detects the amount of light photoelectrically.

Furthermore, in the present invention, in order to eliminate the influence that the positional deviation of the striatum that occurs during the inspection has on the detection accuracy of the abnormally shaped part, the positional deviation of the striatum is detected and an optical mask is installed based on this. It is designed to automatically follow.

Next, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a front view showing the shape of a filament and the arrangement of a detector of a defect inspection device in an embodiment of the present invention, FIG. 2 is a side view thereof, and FIG. 3 is a diagram showing the overall configuration. This example is the first slit floodlight.
As shown in the figure, three slit-shaped lights of uniform width are uniformly projected from the surroundings onto the same plane (XY plane) perpendicular to the feeding direction (perpendicular to the plane of the paper) of the filament 1 to be measured. Slit projectors 2, 2', 2'', three light cutting detectors 3, 3', 3'' that detect the slit light projected onto the slit body from the diagonal side as shown in Fig. 2, and the slit body. In order to detect the positional deviation in the X and Y directions,
Displacement detectors 4, 4' placed just before the slit image detection position, and an optical mask 8 placed on the real image plane of the light cutting detector based on the detected values of the detectors 4, 4'.
a control circuit 5 for feedback to the position of
and a determination circuit 6 for determining and evaluating the detection signals from the optical cutting detectors 3, 3', 3''.The optical cutting detectors 3, 3', 3'' all have the same configuration; As shown by reference numeral 3 in the figure, an imaging lens 7, an optical mask 8 on the light cutting real image surface, and the mask 8
a feed mode 9 for moving on the real image plane,
9', a feeding mechanism 10, a condensing lens 11 for condensing the light transmitted through the optical mask 8, and a photoelectric converter 12.

In addition, the holding mechanism of each part is omitted in FIGS. 1 and 2 of the embodiment. Further, the filament body 1 is also held by guide pulleys, for example, at the front and rear thereof, but this is omitted from the drawing.

The operation of this embodiment will be explained below. When the filament 1 has, for example, a circular cross section, the real image of the detectors 3, 3', 3'', that is, the optically sectioned image, has a smooth arc shape.

This state is illustrated in FIG. 4a. On the other hand, if a convex defect exists on the surface, for example, as illustrated in FIG.
becomes. A mask 8 is placed on the real image plane of the light cutting detector 3.
The pattern shape of the mask is illustrated in FIG. 4c. Here, the mask pattern 15 shown in the shaded area is an opaque area, and the other areas are transparent areas. Therefore, if the striatum 1 is now correctly positioned in the X and Y directions, the light sectioned image 13 will be on the opaque mask pattern 15 in the normal surface area as shown in FIG. 4a. They overlap, and no light passes through the mask. This state is shown in FIG. 4d. On the other hand, in the case of having the protrusions shown in FIG. 4B, as shown in FIG.

This is detected by the photoelectric converter 12. That is, the shape change is detected as the amount of light protruding from the allowable shape of the optically sectioned image, and this is converted into an electrical signal.

If the mask 8 is fixed on the real image plane and the striatum 1 shifts in the X and Y directions, the optically sectioned image will protrude from the pattern 15 of the mask even when detecting a normal area, as illustrated in FIG. , there is a risk of erroneous detection as shown in Fig. 4e. In order to prevent erroneous detection due to misalignment of the filament, the outputs of the displacement detectors 4, 4' are fed back to the mask position via the control circuit 5.

FIG. 6 shows an example of the control circuit 5, which inputs the output signals of the displacement detectors 4, 4' and outputs the amount of movement to the feed motors 9, 9' of the optical cutting detector 3 based on the input signals. This shows the block configuration. This circuit includes reference position setting circuits 17, 17' adders 18, 18 amplifiers 19, 19', 19'', 19
, adder 20, 20' motor drive circuit 21, 2
It consists of one optical cutting detector control circuit 16 consisting of 1'.

The control circuit 5 is configured by arranging a total of three control circuits 16 for each detector. displacement detector 4
is a differential transformer, and the feed motor 9 is a step motor. In addition, the former, air micrometer,
Any displacement meter such as a capacitive displacement detector or an optical stylus detector may be used. The latter may also be a combination of a DC motor and a rotary encoder, a combination of a DC motor and a potentiometer, a linear motor, etc. An adder 18 takes the difference between the output of the displacement detector 4, that is, the coordinate X of the striatum in the X direction at each moment, and a preset reference position _X0 , and calculates the deviation ΔX from the reference position.

Similarly, ΔY is obtained from the adder 18'. The amplifiers 19 to 19 and the adders 20 and 20' undergo coordinate transformation as follows: ΔX=ΔXksinθ+ΔYkcosθ ΔY=−ΔXkcosθ+ΔYksinθ. Here, θ is the angle formed between the X and Y coordinates of the displacement detector and the movement axes X and Y of the mask feeding mechanism, and is a constant that differs depending on the three detection heads. Further, k is a magnification correction coefficient of the detector. △X, △Y are converted into such components △X, △Y in the direction of the movement axis X, Y, and the motor drive circuit 2
1 and 21', the mask is driven by motors 9 and 9' to move by ΔX and ΔY.

In this way, the misalignment or vibration of the striatum during the examination is fed back to the mask position, and the mask is moved by the amount of misalignment, so the mask pattern always reflects the light cut from the normal part of the striatum. Images can be hidden.

FIG. 7 shows an example of the determination circuit 6. This judgment circuit 6 is composed of a threshold value setting circuit 22, a comparator circuit 23, a one shot 24, and a counter 25. The output of the photoelectric converter 12 is compared with the set value of the threshold value setting circuit 22 by the comparator circuit 23. 1 by incrementing the counter 25 when a signal is detected.
The number of defects in each striatum can be determined.

Further, FIG. 8 shows a more detailed configuration of the optical cutting detector 3 in one embodiment of the present invention. The figure shows 7, 8, 9, 10, 11, 1 as explained so far.
2, a shutter 26, a mask holding plate 27, a presser spring 28, and a positioning pin 29. The mask 8 is positioned on the mask holding plate 27 with good reproducibility by the positioning pins 29 and the presser springs 28. First, with the shutter 26 closed, an unexposed film or dry plate is set at the mask position, and the filament is also set. In this state, the shutter 26 is opened for a certain period of time for exposure, and the film or dry plate is developed to obtain a negative pattern of a light cut image.

This is set again at the mask position and used as the mask 8.

FIG. 9 is an explanatory diagram showing the overall configuration of another embodiment in which the present invention is applied to inspection of a rubber hose whose surface has printed marks.

To briefly explain the configuration of FIG. 9 from the symbols, the rubber hose 31 to be inspected, the positioning guide pulley 32, the illumination lamp 33, the slit 34, the illumination lens 35, the imaging lens 36, the mask 37, the condensing lens 38, Half mirror 39, photoelectric converter 4
0, a determination circuit 41, a differential transformer 42, a control circuit 43, and a mask control section 44.

That is, in this embodiment, the slit light projecting section 33,
34, 35, optical section image detection section 36, 37, 38 judgment circuit 41, differential transformer (positional deviation detector) 4
2, a control circuit 43, and a mask control section 44.

The operation of this embodiment will be described below.

The rubber hose 31 to be inspected is held by a guide pulley 32 having a groove with the same curvature as the cross section of the rubber hose.
4 and an illumination lens 35, the slit light of a certain width is detected from an oblique lateral direction, and the light is cut through an imaging lens 36. The image is then optically cut by superimposing it on a mask 37 made from a good sample on the real image plane. Comparison and judgment are performed, and the light leaking behind the mask is detected by the photoelectric converter 40 through the condensing lens 38 and the half mirror 39, and the obtained signal is judged by the judgment circuit 41.

FIG. 10 shows a block diagram of the determination circuit 41.
A filter circuit 45 removes the noise component frequency of the signal detected by the determination circuit 41, and the amplifier 4
6 and then compared with the level obtained by the reference value setting circuit 48 in the comparator circuit 47, and when a defect is determined, the one shot 49 and the detection display counter 50 are operated. Variations in the position of the rubber hose to be inspected are measured by a differential transformer 42, and the obtained measurement value is input to a control circuit 43 and drives a control section 44 to control the mask position so that it is always at the center of the optically sectioned image. ing.

FIG. 11 and FIG. 12 show details of the control section and the control circuit. A reduction gear 52 is connected to the motor 51, and the output shaft and the rotating shaft of the potentiometer 54 are connected by a coupling 53. A rotation bolt 55 is fixed to the other rotating shaft of the potentiometer, and one side is moved. Since the nut 56 is fixed to the mask 57, the mask 57 is moved on the mask moving stage 58 by driving the motor.

In the mask control of this embodiment, position control is performed using a combination of a DC motor and a potentiometer, so as shown in FIG. The adder 62 drives the DC motor 51 and uses the potentiometer rotation angle 64 connected to the motor rotation shaft as a negative feedback amount.
Since the motor rotates in proportion to the positional deviation, the control ends when the motor rotates until the positional deviation is canceled out.

The ratio between the actual positional deviation amount of the rubber hose and the mask control amount can be made the same as the detection magnification of the detector by adjusting the gain of the adder 62, and the ratio can be made the same as the detection magnification of the detector by adjusting the gain of the servo amplifier. Responsiveness can be achieved.

Note that 59 indicates a rubber hose position detection value, and 60 indicates a reference position setting value.

In the embodiment applied to rubber hose inspection, a case was described in which one detector was used, but a plurality of detectors may be applied.

Although the positional fluctuation of the rubber hose to be inspected was measured using a differential transformer, it may also be measured using an electric micro, air micro, or optical measurement method.

In this example, with respect to the central axis of the rubber hose,
Although the illumination was performed from a right angle direction, there is no problem if the illumination is performed from an oblique side direction.

Furthermore, although illumination was performed using a slit light beam with a constant width, detection can also be performed by using wide illumination with a clear bright-dark boundary in place of the constant width slit light beam.

As is clear from the above explanation, the present invention utilizes a photosection method to capture the shape of the striatum and examines changes in shape by comparing it with that of a non-defective product, which is difficult to detect using conventional methods. Warm and gentle unevenness,
It is extremely effective for inspecting shape defects such as those with printed marks on the surface and striatal bodies that move at high speed.
In addition, by detecting changes in the position of the striatum to be inspected and automatically following the mask position, it is possible to prevent false detection and improve detection accuracy.
It is possible to obtain an inspection device suitable for production processes that require high speed and high precision.

Furthermore, the present invention can be applied to various shape inspections because the mask that serves as a standard for determining whether the shape is good or bad can be easily created using a film negative or a dry plate, and can be attached and removed. be able to.

[Brief explanation of the drawing]

Fig. 1 is a front view of a filament shape and defect inspection device showing one embodiment of the present invention, Fig. 2 is a side view thereof, Fig. 3 is an overall configuration diagram, and Fig. 4 is an optical cutting device. It is a diagram showing the principle of comparative judgment in the detector,
FIG. 5 is a diagram showing erroneous detection in that case, and FIG. 6 is a block diagram showing a mask position control circuit.
Fig. 7 is a processing circuit diagram, Fig. 8 is a detailed diagram of the optical cutting detector, Fig. 9 is an explanatory diagram of another embodiment in which the present invention is applied to rubber hose inspection, and Fig. 10 is its processing circuit. FIG. 11 is a detailed explanatory diagram of mask control, and FIG. 12 is a block diagram of the control circuit. 1: striatum, 2, 2', 2'',: slit floodlight,
3, 3', 3'': optical cutting detector, 4, 4': displacement detector.

Claims (1)

[Claims] 1. A slit light projector, which detects the image of the slit light projected from the slit light projector onto the slit body, which is the object to be inspected, and photoelectrically converts the detected slit light image (photocutting image) to generate electricity. A device for inspecting the shape and defect of a filamentous body, comprising a photo-cutting detector having a photoelectric converter for obtaining a signal, and a determination circuit that detects a change in the cross-sectional shape of the filament and a defect based on the electrical signal. The photosection detector is disposed on a photosection image plane of the striatum to block a photosection image corresponding to a normal portion of the striatum and correspond to a portion outside of the normal portion. an optical mask that transmits a light-cut image of the slit, a displacement detector that detects a positional shift of the slit in a plane perpendicular to the direction of movement of the slit, immediately before the projection position of the slit light; and a control circuit that feeds back the output of the device to the optical mask position movement mechanism so that the optical mask placed on the light cutting image plane can be moved in accordance with the positional shift of the filament. Further, the photocutting detector includes a positioning mechanism for removably fixing a negative film or a photographic plate on which a photocutting image of the normal part of the striatum is burned, or an optical mask made from these, and the slit. 1. A shape and defect inspection device for a filament body, comprising a shutter mechanism (for slit light) placed on an optical path of light.