JPS6161041B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting an edge of a black rubber object, that is, a boundary line where two adjacent planes intersect.

For example, in tire manufacturing, when the tread extruded by an extruder is conveyed by a conveyor, the length (or width) of the tread is measured.In this case, the edge of the tread end is detected. Generally, the length is measured by operating a counter or the like based on the signal. In this method of measuring the size of an object, the position of the end must be detected accurately. The present invention provides a method for accurately detecting the edges of an object using a reflective photoelectric switch.

As is well known, a reflective photoelectric switch is a type of electronic switch in which a light emitter and a light receiver are integrated into a case, and the light emitted from the light emitter is reflected by an object and is received by the light receiver. , which is turned on and off based on changes in the amount of light received. Therefore, if the object is black, such as tored rubber, it is generally believed that even if light is irradiated, most of the light will be absorbed by the object and only a weak reflected light will be obtained, making accurate detection impossible. Reflective photoelectric switches are not used to detect the edges of objects; transmissive photoelectric switches are generally used for black objects of this type. As shown in FIG. 1, the tread rubber 1 usually has tapered surfaces 2 and 3 at both cut ends, and tapered surfaces 4 and 5 on both sides. Therefore, to measure the length of such an object, a transmission-type photoelectric switch, that is, a transmitter P ₁ and a receiver P ₂ are placed on the center line 6 of the thickness of the tread 1 and Midpoint 3 between point 2a and the other cut end surface 3
a is detected and the distance between both points 2a and 3a is measured. However, in the case of a soft object such as treaded rubber, when it is conveyed on the conveyor 8, it meanders in most cases and is not conveyed in an accurate posture, so that measurement errors such as measuring the length of a diagonal line are likely to occur. Further, with this method, it is impossible to measure the width W of the shoulder portion 7 of the tread, and in this case, an expensive and complicated device using an image sensor, a vidicon, etc. is required.

As a result of various studies, the inventors of the present invention have found that even if sufficient reflected light is obtained by increasing the brightness of the light source with black rubber, the reflected light is diffused significantly, resulting in insufficient S/N.
Although a ratio could not be obtained, it was discovered that red light or light in the near-infrared region has a wavelength with a small diffusivity of reflected light, and a reflective type using a red light or near-infrared light emitting diode (wavelength 6000 to 10000 Å) as a light source was developed. They discovered that using a photoelectric switch can detect minute changes in the angle between the surface of the object and the photoelectric switch (detection angle), and developed a method to accurately detect the edges of black objects using this principle. .

Using a reflective photoelectric switch 9 having a red light or near red light emitting diode as described above as a light source,
As shown in FIG. 2, a sample rubber 10 of the same quality as smooth unvulcanized tire tread rubber is irradiated, and the angle θ (detection angle) of the photoelectric switch 9 with respect to the normal 11 of the surface of the sample rubber 10 is varied. Finally, the distance L at which the photoelectric switch 9 operates was measured. The result is the third
As shown in the figure. In the figure, curve A is a reflection type photoelectric switch (hereinafter referred to as the A switch) that uses a red light emitting diode (wavelength of about 6600 Å) as a light source, and curve B is a near infrared light emitting diode (wavelength of about 6600 Å).
This is the limit line at which the photoelectric switch operates when a reflective photoelectric switch (hereinafter referred to as the B switch) is used with a light source of 9400 Å). That is, A, B
Both switches operate in the area surrounded by curves A and B and the X and Y axes.

By utilizing the above principle, it is possible to detect the boundary line, ie, the edge 13, where two planes, for example 12a and 12b, of a black object 12 such as tread rubber intersect, as shown in FIG. for example,
The plane 12b is a cut end surface, and the cut end surface 12
Assuming that the angle α between b and the extension line 12a' of the surface 12a is 9 degrees,
When attempting to detect the edge 13 portion where
The reflective photoelectric switch 9 may be placed at a position where it is not detected. Looking at the graph in Figure 3, we see that A
In the switch, the detection distance when the detection angle θ is 9 degrees is about 55 mm. Therefore, conversely, if a photoelectric switch is set at a point 55 mm from the surface of an object, the photoelectric switch will turn off when the angle α with the surface becomes 9 degrees or more. Therefore, if the A switch 9 is installed so that the distance L' taken in the vertical direction from the surface 12a of the object 12 is 55 mm or more, the object 1
2 is conveyed in the direction of arrow 14, or switch 9
is moved in the direction of arrow 15, and the moment the edge 13 crosses the detection point, the photoelectric switch 9 is turned off and the edge 13 is detected. If the reflective photoelectric switch 9 is a B switch, looking at curve B in Figure 3, the detection distance is approximately 70 mm when the detection angle is 9 degrees, so the vertical distance L' from the surface of the object 12 is set to 70 mm. Edges 13 can be detected if installed above. Also, set the A switch's L′ to 55mm, and the B switch's L′ to 55mm.
When L' is set to 70 mm, edge portions 13 with α of 9° or more can be detected. Although either the A switch or the B switch can be used as a reflective photoelectric switch, the B switch is more preferable because it allows a longer detection distance.

In the above example, the light emitting diode in the red light region has a wavelength of approximately 6600 Å (GaAsP), and the light emitting diode in the near infrared region has a wavelength of approximately 9400 Å.
(GaAs), but the light source is 6000 ~
Light-emitting diodes in the 10,000 Å range can be used, particularly preferably light-emitting diodes in the near-infrared range of 7,700 to 10,000 Å are used. Furthermore, the object to be detected is not limited to treaded rubber, but any black rubber object having an edge portion can be applied.

As described above, according to the present invention, by installing a reflective photoelectric switch using a red light or near-infrared light emitting diode as a light source at a specific distance, it is possible to accurately detect the edge of a black rubber object. Since this reflective photoelectric switch responds to minute changes in angle, it can accurately detect even small changes in angle at the edge. Therefore, the method of the present invention can be effectively used for indirect dimension measurement of black rubber objects.

[Brief explanation of the drawing]

Figures 1A and 1B are a plan view and a side view showing an example of a method for detecting the edge of tire tread rubber using a transmission type photoelectric switch, and Figure 2 is a side view showing an example of a method for detecting the edge of tire tread rubber using a transmission type photoelectric switch, and Figure 2 shows a method for detecting a black rubber object using a reflection type photoelectric switch used in the present invention. FIG. 3 is a graph showing the detection characteristics, and FIG. 4 is an explanatory view showing an embodiment of the edge detection method according to the method of the present invention. 12: Black rubber object, 12a, 12b: Plane,
13: Edge part, 9: Reflective photoelectric switch.

Claims (1)

[Claims] 1. In a method for detecting a boundary line (edge part) by detecting the angle formed between one plane of a black rubber object and another plane that intersects this, a light emitting diode in the red light or near infrared region is used. A reflective photoelectric switch using a light source as a light source is installed at a distance that can detect the plane but does not detect other planes, and the rubber object and the photoelectric switch are moved relative to each other to detect the edge portion. Method for detecting edges of black rubber objects. 2. The method according to claim 1, wherein the wavelength of the near-infrared rays is 7,700 to 10,000 Å.