JPS6161322B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring the width of black rubber objects, such as tire tread rubber.

In tire manufacturing, when the tread rubber extruded by an extruder is conveyed by a conveyor, the length of the tread in the longitudinal and width directions 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 this detection signal. In such a method for measuring the dimensions of an object, the position of the end must be detected accurately. The present invention uses a reflective photoelectric switch to accurately detect the edge of a black rubber object, thereby making it possible to accurately measure its dimensions.

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 treaded 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. Therefore, when the black rubber object is a treaded rubber 1 as shown in FIG. 1 in the width direction, and receives the scan position signal from the position sensor 7 and the arithmetic unit 5.
computer 8 based on the profile signal from
Generally, a method is adopted in which the shoulder width W is calculated and displayed on the display 9. Although this method can measure shoulder width, it requires complicated data processing and has the disadvantage that the entire device is extremely expensive.

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. It was discovered that when a photoelectric switch is used, minute changes in the angle between the surface of the object and the photoelectric switch (detection angle) can be detected.Using this principle, the edge of a black rubber object can be accurately detected, with high precision. This is the completed dimension measurement method.

Using a reflective photoelectric switch 10 using a red light or near red light emitting diode as described above as a light source,
As shown in FIG. 2, a sample rubber 11 of the same quality as smooth unvulcanized tire tread rubber is irradiated, and the photoelectric switch 10
The distance L over which the photoelectric switch 10 operates was measured by varying the angle Θ (detection angle). The results are shown in FIG. In this figure, curve A is a reflection type photoelectric switch (hereinafter referred to as A switch) that uses a red light emitting diode (wavelength of about 6600 Å) as a light source.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,
Both B switches operate in the area surrounded by curves A and B and the X and Y axes.

The present invention utilizes the above principle to provide edge portions 13a, 13 on both sides of the tread rubber 1 as shown in FIG.
b is detected and the dimension between the edge portions 13a and 13b, that is, the shoulder width W is measured. Generally, the upper surface of the tread rubber 1, that is, the shoulder surface 14, is almost flat, and both sides thereof are tapered surfaces 15a and 15b.

The reflective photoelectric switch 10 has a tread rubber 1
The shoulder surface of is detected, but the tapered surface 15a, 1
5b is attached to the holder 16 with a vertical distance L' from the shoulder surface 14 set so as not to be detected. The holder 16 is supported by a guide rail 18 provided horizontally on a frame 17. A nut 19 is fixed to the holder 16, and this nut 19 is screwed onto a ball screw 20. The ball screw 20 is rotated via a motor 21 and a belt 22. Rotation of the ball screw 20 is applied to a rotary encoder 24 via a timing belt 23. 25a and 25b are limit switches, and 26 is a lock attached to the holder 16.

The distance L' is related to the angle α between the tapered surfaces 15a and 15b on both sides (the angle formed between the extension line 14' of the shoulder surface 14 and the tapered surfaces 15a and 15b). Assume now that this angle α is 9°. Looking at the graph in FIG. 3, the detection distance for the A switch is approximately 55 mm when the detection angle Θ is 9 degrees. Therefore, conversely speaking, 55mm from the surface of the object
If a photoelectric switch is set at the point, the photoelectric switch will turn off if the angle between the point and the surface becomes 9 degrees or more. Therefore, if the A switch 10 is installed so that the vertical distance L' from the surface 14 of the tread rubber 1 is 55 mm or more, by scanning the tread rubber 1, the switch can On, tapered surface 15
a, 15b, and the edge part 13
a, 13b are detected.

If the reflective photoelectric switch 10 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 tread rubber 1 must be 70 mm or more. If the sensor is installed at the edge portions 13a and 13b, the edges 13a and 13b can be detected. Both the A switch and the B switch can be used, but the B switch is more preferable because it allows a longer detection distance.

In the above embodiment, the light emitting diode in the red light range uses a wavelength of 6,600 Å (GaAsP), and the near-infrared light emitting diode uses a wavelength of about 9,400 Å (GaAs), but the light source uses a light emitting diode in the wavelength range of 6,000 to 10,000 Å. Light-emitting diodes can be used, particularly preferably light-emitting diodes in the near-infrared green region of 7700 to 10000 Å. Further, if both the A and B switches are set at a constant distance, for example, the A switch is set to 55 mm and the B switch is set to 90 mm, all edges with α of 9° or more can be detected.

Next, the width W of the shoulder surface is measured in the fifth and sixth steps.
This will be explained with reference to the figures. By rotating the ball screw 20 via the motor 21 and belt 22, the holder 16 moves along the guide rail 18, and the locker 26 moves the limit switches 25a, 2.
5b, the rotation is reversed, and as a result, the photoelectric switch 10 scans the upper surface of the tread rubber 1. Further, the rotation of the ball screw 20 is transmitted to a rotary encoder 24 by a timing belt 23, and a timing pulse is given to an AND gate 27. On the other hand, the photoelectric switch 10 is on while scanning the shoulder surface 4, and off while scanning the tapered surfaces 15a and 15b. Upon detection of the rising edge signal of the photoelectric switch 10, that is, one edge portion 13a, a pulse is output from the one shot circuit 28, and the counter 29 outputs a pulse.
is reset, and at the same time the AND gate 27 is opened and the timing pulses are counted while the photoelectric switch 10 is on. The value of this counter 29 is taken into the data clutch 30 by the falling signal of the photoelectric switch 10, that is, by the pulse output from the one-shot circuit 33 via the inverter 32 upon detection of the other edge portion 13b, and is displayed. displayed on the display 31.

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 has the advantage that the length between the edges of a black rubber object can be measured accurately and can be realized in a much simpler method than the conventional method.

[Brief explanation of the drawing]

Figures 1A and 2B are explanatory diagrams showing an example of the conventional tread width measuring method, Figure 2 is an explanatory diagram showing the detection characteristics of the reflective photoelectric switch used in the present invention for black rubber objects, and Figure 3 is an explanatory diagram showing an example of the conventional tread width measurement method. 4 is a longitudinal sectional view showing an embodiment of the measuring device used in the method of the present invention, FIG. 5 is a measurement circuit diagram, and FIG. 6 is a time chart. 1... Rubber object (treaded rubber), 10... Reflective photoelectric switch, 15a, 15b... Tapered surface, 14... Surface (shoulder surface), 13a, 1
3b...Edge portion, 24...Rotary encoder, 20...Ball screw, 21...Motor, 29
……counter.

Claims (1)

[Claims] 1. A reflective photoelectric switch that uses a light emitting diode in the red or near-infrared region as a light source is installed in a position where it can detect the surface of the rubber object but does not detect the tapered surface that intersects with the surface, and the photoelectric switch is placed on the rubber object. 1. A method for measuring the width of a black rubber object, characterized in that the length between a pair of edge portions is measured by scanning to detect an edge portion, and counting timing pulses based on this detection signal.