JPS6161042B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring the length 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 rubber is measured.In this case, the edge of the tread end is detected and a counter is set based on this detection signal. Generally, the length is measured by operating a device such as the following. In this method of measuring the size 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.
This makes it possible to measure dimensions accurately.

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, it is generally believed that if the object is black, such as treaded rubber, 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 this type of black object. 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 the midpoint of one cut end surface 3 is measured. Midpoint 3a between 2a and the other cut end surface 3
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, as another dimension measurement method, a method using an image sensor, a vidicon, etc. is known, but this method has the drawback of being a very complicated and expensive device.

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 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.

The present invention utilizes the above principle to detect the edge portion of the tread rubber 12 and measure its dimensions as shown in FIG. Generally, the cut ends of the tread rubber 12 at both the front and rear ends are tapered surfaces 13 and 14, and the length is from the front edge portion 15 to the rear edge portion 16, that is, the boundary line where the surface 17 and the tapered surface 14 intersect. The length is the length of the treaded rubber. Therefore, the front edge portion 15 and the rear edge portion 16 are detected by a reflective photoelectric switch as described above, and the length is measured based on this detection signal. Reflection type photoelectric switch 9 has treaded rubber 1
The perpendicular distance L' from the surface 17 is set so that the surface 17 of No. 2 is detected but the tapered surface 14 is not detected. Further, it is placed near the inverted portion of the tip of the conveyor belt 8 so as not to detect the surface of the conveyor belt 8.

The distance L' is related to the angle α of the rear end tapered surface 14 (the angle formed between the extension line 17' of the surface 17 and the tapered surface 14). Assume now that this angle α is 9°. So, if you look at the graph in Figure 3,
In the A switch, the detection distance is approximately 55 mm when the detection angle θ is 9 degrees. Therefore, conversely, if a photoelectric switch is set at a point approximately 55 mm from the surface of an object, the photoelectric switch will turn off when the angle between the switch and the surface becomes 9 degrees or more. Therefore, the distance taken in the vertical direction from the surface 17 of the tread rubber 12
If the A switch 9 is installed so that L' is 55 mm or more, as the tread rubber 12 is moved in the direction of the arrow 36, the front end edge 15 is first detected, the photoelectric switch 9 is turned on, and the rear end edge is detected. Part 1
The photoelectric switch 9 is turned off at the moment when 6 exceeds the detection point.

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 tread rubber 12
The edge portion 16 can be detected if the vertical distance L' from the surface is set at 70 mm or more. 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 example, the infrared light emitting diode has a wavelength of approximately 6600 Å (GaAsP), and the near infrared light emitting diode 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.

By setting the reflective photoelectric switch 9 as described above, the tip edge portion 15 of the tread rubber 12 conveyed at a constant speed on the conveyor belt 8 is
and the rear edge portion 16 are detected by the photoelectric switch 9. On the other hand, the pulley 8a of the conveyor belt 8
The rotation is transmitted to the rotary encoder 18 to generate a timing pulse, which is applied to the counter 19. The photoelectric switch 9 is activated by detecting the tip edge portion 15.
is turned on, thereby setting the counter 19 and starting counting timing pulses,
Upon detection of the trailing edge portion 16, the photoelectric switch 9 is turned off and the counter 19 is reset. By converting this counter value into length, the length between both edge portions 15 and 16 can be measured.

5 to 8 show a second embodiment of the present invention,
This is a more improved measurement method that eliminates measurement errors caused by slips and meandering of the tread rubber 12 on the belt 8, reflected light from the belt 8, etc. Fifth
In the figure, a pair of photoelectric switches 9a and 9b are installed with a distance X between them. This distance X is shorter than the length between the edge portions 15 and 16 of the tread rubber 12. The rear photoelectric switch 9b detects both the surface of the belt 8 and the surface 17 of the tread rubber 12, and the height is such that the tapered surface 14 is not detected, and the front photoelectric switch 9a is also set at the same height. However, the front photoelectric switch 9a is placed near the reversal part of the belt so as not to detect the belt 8. The front photoelectric switch 9a constitutes a unit 22 together with a rotating disk 20 and a rotary encoder 21. The unit 22 includes guide rods 23, 23.
The guide rod is inserted into a linear bearing 25 of the support 24. Further, the unit 22 is suspended from a support 24 by means of a tension spring 26, so that the rotary disk 20 is brought into contact with the tread rubber 12 with appropriate pressure.

Next, the measurement operation will be explained with reference to FIGS. 7 and 8. When the photoelectric switch 9a detects the tip end portion 15 of the tread rubber 12, the one shot circuit 2
One pulse is output from 7 to reset the counter 30. At the same time, flip-flop 29 is set, and this set signal is input to counter 30. As the tread rubber 12 moves, the rotating disk 20 rotates, and a timing pulse is input from the rotary encoder 21 to the counter 30, and the flip-flop 2
Counting of timing pulses is started by the set output of 8. Next, when the photoelectric switch 9b detects the rear edge portion 16, this detection signal enters the flip-flop 29 via the inverter 34.
This is reset, and the counter 30 stops with this reset output. At the same time, one pulse is output from the one-shot circuit 28 to lock the counter 30. The output of the counter 30 is sent to the digital switch 32.
is added by the adder 31 and the added value is displayed on the display 33. This digital switch 3
2, the distance X between the photoelectric switches 9a and 9b is set, and the counter value indicates the counter value from when the leading edge portion 15 is detected to when the trailing edge portion 16 is detected (unit of length). Therefore, the length between the edge portions 15 and 16 can be immediately displayed on the display 33.
In addition, when transporting the rubber object at a constant speed,
The same effect can be obtained by inputting clock pulses from a timer or the like to the counter 30 instead of the rotary encoder pulses. Furthermore, the seventh
Reference numeral 35 in the figure is an interface circuit including a level detector. Further, the signal waveforms at portions a, b, c, and d in FIG. 7 are shown in the timing chart of FIG. 8.

In the above embodiment, the length measurement of the treaded rubber was explained, but in addition to this, there are other ways to measure the length of the treaded rubber.
Any material having an edge portion is applicable. 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 70 mm, all edges with α of 9° or more can be detected.

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, the edge of a black rubber object can be accurately detected. 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 accurately measure the length between the edges of a black rubber object,
Moreover, it has the advantage that it can be achieved in a much simpler manner than conventional methods.

[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 end of tire tread rubber using a transmission type photoelectric switch, and Figure 2 is a plan view and side view showing an example of a method for detecting the edge of tire tread rubber using a transmission type photoelectric switch. 3 is a graph showing the detection characteristics; FIGS. 4A and 4B are a side view and a front view of the first implementation of the method of the present invention; FIGS. In the second embodiment of the invention method, Fig. 5 is a side view, and Fig. 6 is a side view.
The figures are a cross-sectional view taken along the line -- in FIG. 5, FIG. 7 is a measurement circuit diagram, and FIG. 8 is a time chart. 8: Conveyor belt, 9: Reflective photoelectric switch, 12: Black rubber object (treaded rubber), 1
7: Surface, 14: Tapered surface, 16: Edge portion, 1
8, 21: Rotary encoder, 19, 30:
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 at a position where it can detect the surface of the rubber object but not the tapered surface that intersects with the surface, and the rubber object is conveyed until both ends are detected. detecting the edge of with the reflective photoelectric switch,
A method for measuring the length of a black rubber object, characterized by counting timing pulses based on this detection signal and measuring the length between the edge portions at both ends.