JPS6215076A - Wear amount detecting device for grindstone of grinder - Google Patents

Abstract

PURPOSE:To enable the light of a luminous means to be discriminated from grinding spark or the like by providing a luminous modulating means applying frequency modulation of a predetermined frequency to light emission of the luminous means and a frequency component extraction means extracting frequency component from the received signal of a light receiving means. CONSTITUTION:LED 3, 4 of luminous side of two pairs of photo couplers of a detecting head 2 in a wear amount detecting device 1 of the grindstone of a grinder are connected in series to each other and supplied with power through a transistor 5. The frequency of an oscillator 6 for driving the transistor 5 is made 10kHz apart from the change frequency of disturbance light such as grinding spark, and the LED 3, 4 emit light intermittently in 10kHz frequency. While, the frequency band passing band pass filters 9, 10 connected to phototransistors 7, 8 of the light receiving side is set around 10kHz, and only signal component from LED 3, 4 is extracted through the filters 9, 10, and wear of a grindstone T of the grinder in a process of grinding can be detected without effect of the disturbance light.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a grinder whetstone wear amount detection device, and in particular, a device for detecting the wear amount of a grinder whetstone attached to a polishing/grinding robot without stopping its work. It relates to a device for detecting.

"Prior art" In the case of a robot used for general grinding, etc., the outer diameter of the attached grinder whetstone is, for example, 17 mm when new.
It is known that the outer diameter gradually decreases due to wear as it is used, and eventually becomes about 120 wm, for example.

Therefore, it is necessary to control the robot to compensate for such a change in the outer diameter of the grinder wheel.

For this reason, for example, in JP-A-58-13184 and JP-A-58-15991, an apparatus has been proposed that detects the amount of wear on a grinder whetstone and corrects the amount of grinding of the grinder.

In such a device, a light receiver detects that the light beam emitted from the emitter is interrupted by the peripheral edge of the grinder wheel, the position of the peripheral edge of the grinder wheel is known, and the grinder is adjusted based on the change in position. An optical grinder grindstone wear amount detection device is used to detect the amount of wear on the grindstone.

"Problems with the Prior Art" The above-mentioned conventional optical grinder grindstone wear detection device has a problem in which the receiver detects light other than the light beam emitted from the light emitter, such as grinding sparks or illumination light, resulting in malfunction. be.

In other words, even though the light beam emitted from the emitter is blocked by the peripheral edge of the grinder grinding wheel, the interruption may not be detected due to disturbance light such as grinding sparks entering the receiver. Therefore, the position of the peripheral end of the grinder whetstone may be misidentified, and the amount of wear may not be accurately detected.

``Object of the Invention'' The object of the present invention is to provide a grinder grindstone wear amount detection device that prevents malfunctions caused by ambient light such as grinding sparks and maintains high reliability even during grinding operations. be.

"Structure of the Invention" A grinder whetstone wear amount detection device of the present invention includes a light emitting means and a light receiving means for optically detecting the peripheral edge of a grinder whetstone. and a frequency component extracting means for extracting the predetermined frequency component from the light reception signal of the light receiving means, thereby separating the light of the light emitting means from disturbance light such as grinding sparks. Its structural feature is that it is distinguishable.

"Function" There are various types of disturbance light, but the representative ones are firstly grinding sparks, secondly illumination light, and thirdly natural light.

Focusing on the changes in the strength of these lights, it is thought that there is almost no change in the grinding sparks as they are generated continuously over a short period of time. There is a change due to (z), but it is thought that there is no change in natural light.

Therefore, if the light emission of the light emitting means is intermittent at a predetermined frequency, for example, several kHz, which is different from the changing frequency of the disturbance light, and only this frequency component is extracted from the light reception signal of the light receiving means,
This serves as a scale to suppress the influence of ambient light.

"Example" The present invention will be described in more detail below based on the example shown in the drawings. Here, FIG. 1 is a configuration explanatory diagram of a grinder grindstone wear amount detection device according to an embodiment of the present invention, FIG. 2 is an external view including a partial sectional view of the device shown in FIG. 1, and FIG. 3 is a detection head. FIG. 4 is a sectional view showing another example of the configuration of the detection head, and FIG. 5 is a view corresponding to FIG. 1 of another embodiment of the present invention. Note that the present invention is not limited to these Examples.

As shown in FIG. 1, a grinder grindstone wear amount detection device 1
The detection head 2 has two pairs of photocouplers arranged side by side with a slight gap between them. The LEDs 3.4 on the light emitting side of the photocoupler are connected in series and supplied with power via the transistor 5.

The transistor 5 is driven by an oscillator 6 whose frequency is, for example, 10 kHz.

Therefore, the LEDs 3 and 4 will emit light intermittently at a frequency of 10 kHz, for example.

Phototransistor 7 on the light receiving side facing the LED 3
is connected to a band pass filter 9, and the frequency band that the bad pass filter 9 passes is set to around 10 kHz in accordance with the frequency of the light emitting side.

Further, a phototransistor 8 on the light receiving side opposite to the LED 4 is also connected to a bandpass filter IO.

Disturbance light other than the light beam from the LED 3.4, such as grinding sparks and illumination light, mixes into the phototransistor 7.8, but since these disturbance lights do not substantially have a frequency component of 10 kHz, a bandpass filter is used. 9.10, only the signal component from the LED 3.4 is extracted, and the influence of ambient light is removed.

The outputs of bandpass filters 9 and 10 are rectified and
It is connected to the circuits 11 and 12 and converted to direct current.

The outputs of these rectifier/smoothing circuits 11 and 12 are input to comparators 13 and 14 having hysteresis, respectively.

When the output values of the rectification/smoothing circuits 11.12 rise and exceed the predetermined upper limit value vu, the outputs of the comparators 13.14 each become "H" level, while the output values of the rectification/smoothing circuits 11.12 increase. falls below the predetermined lower limit value V, the outputs of the comparators 13 and 14 respectively become r.
Becomes LJ.

When the outputs of these comparators 13 and 14 are both "H", the positive input AND gate 15 outputs rHJ, and otherwise outputs "L".

Further, when the outputs of the comparators 13 and 14 are both "L", the negative input AND gate 16 outputs "H", and otherwise outputs rLJ.

The output of the positive input AND gate 15 is input to the J input of the flip-flop 17 at J-, and the output of the negative input AND gate 16 is input to the J input of the flip-flop 17.
The output of J- is input to the input of flip-flop 17.

A clock is continuously supplied to the clock input of the flip-flop 17 in J-. Therefore, this J-flip-flop]7 works like an R-S flip-flop.

The Q output of the flip-flop 17 is input to the servo amplifier 20 via the buffer amplifier 18 and the changeover switch 19.

Servo amplifier 20 drives servo motor 21.

When the servo motor 21 is driven, its rotational motion is converted into linear motion of the sliding shaft 23 by the ball screw 22, as shown in FIG.

A drive shaft 25 is attached to the tip of the sliding shaft 23 via a ball joint 24, and the detection head 2 is attached to the tip of the drive shaft 25.

The amount of movement of the sliding shaft 23 is read by a potentimeter 26, and the output of the potentiometer 26 is outputted to the outside (for example, to a robot control device) as a peripheral end position signal a of the grinder whetstone T. It is also connected to the negative input of the deviation amplifier 27.

There is.

An initial position l signal is input to the positive input of the deviation amplifier 27 from the outside.

The output of the deviation amplifier 27 is input to the servo amplifier 20 via the changeover switch 19.

The changeover switch 19 selects the input signal to the servo amplifier 20, and the changeover is performed by receiving a changeover signal C from the outside.

Next, the operation of this grinder whetstone wear amount detection device 1 will be explained.

First, an initial position signal S is applied from the outside, and the changeover switch 19 is switched to the deviation amplifier 27 side by the changeover signal C.

As a result, the servo amplifier 20 drives the servo motor 21 to move the detection head 2 to the initial position and stop it. In this position, the peripheral edge of the grinder whetstone T is usually
Neither the light beams 3 nor 4 are blocked.

If the light beams of LEDs 3, 4 are not interrupted, both phototransistors 7, 8 are driven by the light beams. Therefore, a 10kHz pulse is continuously output from the bandpass filter 9.10, and the rectification/smoothing circuit 11.12
The output values of are each larger than the upper limit value vu. Therefore, the outputs of the comparators 13 and 14 are both rHJ, the output of the positive input AND gate 15 is "H", and the output of the negative input AND gate 16 is rLJ. Therefore, the Q output of the flip-flop 17 at J- becomes rHJ.

Here, the changeover signal C is inputted from the outside and the changeover switch 19 is
When switched to the buffer amplifier 18 side, rHJ of the Q output of the flip-flop 17 is input to the servo amplifier 20 via the buffer amplifier 18 to J-, and the servo amplifier 20
drives the servo motor 21 so that the detection head 2 approaches the grinder whetstone 7.

As shown in FIG. 1, since the photocoupler consisting of the LED 3 and the phototransistor 7 is located closer to the grinder wheel T than the photocoupler consisting of the LED 4 and the phototransistor 8, the light beam of LP01 is First, it is interrupted at the peripheral end of the grinder whetstone T.

Then, the phototransistor 7 will no longer be driven by the light beam, and the bandpass filter 9 will not receive a signal with a frequency component of 10 kHz, so its output will be substantially O.
Therefore, the output value of the rectifier/smoothing circuit 11 becomes below the lower limit value vI, and the output of the comparator 13 becomes rLJ.

On the other hand, since the phototransistor 8 is driven by the light beam of the LED 4, the output of the comparator 14 remains rHJ.

Therefore, the outputs of 15 and 16 become "L".

Since the Q output does not change when both the J input and the input are rLJ, it remains rHJ, so the servo motor 21 continues to be driven, and the detection head 2 is further advanced toward the grinder whetstone T.

When the grinder wheel T finally blocks the light beam of the LED 4, the outputs of the comparators 13 and 14 both become rLJ, as understood from the above description. Therefore, the output of the negative input AND gate 16 becomes rHJ, and the Q output becomes "L
”.

The Q output rLJ of the flip-flop J- becomes a stop signal for the servo motor 21, and the servo motor 21 is stopped.

Thus, the detection head 2 stops at the position where the light beam of the LED 4 is blocked by the peripheral edge of the grinder whetstone T.

The circumferential edge position signal a at this time represents the position of the circumferential edge of the grinder whetstone T.

As wear progresses due to use of the grinder whetstone T, the peripheral edge portion retreats. Then, the light beam of the LED 4 reaches the phototransistor 8 again.

When the phototransistor 8 is driven by the light beam of the LED 4, the output of the comparator 14 becomes rH as described above.
It becomes J.

When the output of the comparator 14 becomes rHJ, the output of the negative input AND gate 16 becomes rLJ, so the input of the flip-flop 17 becomes J-.

Both K inputs become rLJ.

Therefore, the Q output is maintained at "L" and the position of the detection head 2 does not move.

As the wear progresses further and the peripheral edge of the grinder grinding wheel T retreats, and the light beam of LP01 also reaches the phototransistor 7, as described above, the positive input AND gate 1
Since the output of 5 becomes rHJ, the Q output becomes rHJ,
The servo motor 21 is driven and the detection head 2 moves toward the grinder whetstone T again.

In this way, when the peripheral edge of the grinder whetstone T blocks the light beam of the LED 4, the detection head 2 stops again.

Here, the value of the circumferential edge position signal a changes by the pitch between LP01 and LED4.

That is, according to this grinder whetstone wear amount detection device 1, the wear amount of the grinder whetstone T can be detected in units of pitches between two photocouplers.

The pinch between the two photocouplers is the difference in distance from the center of the grinder whetstone T to the photocoupler, and can be arbitrarily reduced by shifting the direction from the center of the grinder whetstone T, but in practice, 0.5-1~
It is preferable to set it to about 1.0.

3rd Ff! Is J a phototransistor in which one LED 3' serves as the light emitting side of two photocouplers, and the light beam is attached at a different position? This is an example of a configuration in which detection is performed at ', 8'.

FIG. 4 shows that by guiding light to the detection head 2" using optical fibers 30, 31, 32, LP01" and phototransistors 7" and 8" are provided at different locations, and the detection head 2"
This is an example of a configuration that allows for miniaturization.

Fig. 5 Detection head 35 with only one photocoupler
This figure shows an example provided in .

As shown in the figure, the detection head 35 and the comparator 3
Components other than 6 are all numbered the same as the components of the grinder grindstone wear amount detection device 1 shown in FIG.
This indicates that these are similar components.

That is, this grinder whetstone wear i detection device 40 is different from the grinder whetstone wear amount detection device 1 in the following points.
The only two points of difference are that the detection head 35 includes only a III photocoupler and that the hysteresis width of the comparator 36 is larger than the hysteresis width of the comparators 13 and 14.

The operating principle of this grinder whetstone wear detection device 40 is that the state in which the peripheral end of the grinder whetstone T blocks the light beam of the LED 3 exhibits an analog change. In other words, since the light beam has a certain width, when the peripheral edge of the grinder wheel T enters the light beam, the light beam is not suddenly interrupted, but is gradually interrupted, so that rectification and The change in the output value of the smoothing circuit 11 shows an analog change in that it is initially larger than the upper limit value V, but gradually becomes smaller, and finally becomes smaller than the lower limit value V.

Therefore, when the detection head 35 advances toward the grinder whetstone T, the detection head 35 does not stop until the peripheral edge of the grinder whetstone T blocks most of the light beam. On the other hand, the point at which the grinder grinding wheel T starts moving again from the stopped state is at the position where the peripheral edge of the grinder whetstone T has almost passed through the light beam.
There is a certain amount of width between the raincoats.

In other words, according to this grinder whetstone wear amount detection device 40, by providing a width large enough to form a light beam and a hysteresis large enough to form a comparator, the width determined by these is used as a pitch. This allows the amount of wear on the T to be detected.

In addition, in the above-mentioned grinder whetstone wear detection device 1.40, even if the comparators 13, 14.36 do not have hysteresis, the detection head 2.35 can theoretically be made to follow changes in the peripheral edge of the grinder whetstone T. However, since hunting may occur, it is preferable to provide hysteresis.

Still another embodiment is one in which the light emission of the LEDs 3 and 4 is modulated by a signal obtained by superimposing a sine wave or a triangular wave on a DC component.

Still another embodiment is one in which only the signal component of the light emitting means is extracted by a circuit that extracts the same phase component using phase detection.

"Effects of the Invention" According to the present invention, in a grinder grinding wheel wear amount detection device having a light emitting means and a light receiving means for optically detecting the peripheral edge of crushed stone in a grinder, the light emitting means emits light at a predetermined frequency. There is provided a grinder whetstone wear amount detection device characterized by comprising: a light emission modulation device that applies frequency modulation; and a frequency component extraction device that extracts the predetermined frequency component from the light reception signal of the light reception device. By using a signal with a frequency that does not substantially exist, it is possible to distinguish between the disturbance light and the light from the light emitting means, so highly reliable detection can be performed without being affected by disturbance light such as grinding sparks from a grinder.

Therefore, the amount of wear on the grinder whetstone can be suitably continuously detected even during grinding work, and by correcting the amount of wear, it is possible to perform finishing with a high degree of detection.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the configuration of a grinder grindstone wear detection device according to an embodiment of the present invention, Fig. 2 is an external view including a partial sectional view of the device shown in Fig. 1, and Fig. 3 is a deformation of the detection head. FIG. 4 is a cross-sectional view showing another example of the configuration of the detection head, and FIG. 5 is a view corresponding to FIG. 1 of another embodiment of the present invention. (Explanation of symbols) 1.40... Grinder grinding wheel wear detection device 2.35
...Wind head 3.4.3', 3"...LED 5...Transistor 6...Oscillator?,,8.
7', 8',? ",8"...Phototransistor 9.10...Band pass filter 11.12...Rectification/smoothing circuit 13.14.36...Comparator.

Claims (1)

[Scope of Claims] 1. In a grinder grinding wheel wear detection device having a light emitting means and a light receiving means for optically detecting the peripheral edge of the grinder grinding wheel, the light emission of the light emitting means is frequency modulated at a predetermined frequency. and frequency component extracting means for extracting the predetermined frequency component from the light reception signal of the light receiving means, thereby making it possible to distinguish the light of the light emitting means from disturbance light such as grinding sparks. Grinder whetstone wear amount detection device. 2. The grinder wear amount detection device according to claim 1, wherein the predetermined frequency is about 10 kHz.