JPH0829494B2 - Method and apparatus for detecting contact state of rotating grindstone - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a dressing tool for a grinding wheel,
Alternatively, it is used in the field of grinding technology for grinding a workpiece with a rotary grindstone.

[0002]

2. Description of the Related Art When dressing a rotating grindstone or grinding a workpiece with a rotating grindstone, the rotating grindstone is usually rotated and brought close to a dresser or a workpiece, and the dresser or the workpiece is rotated. Dressing or grinding is started with the whetstone abutting. At this time, if the rotating grindstone comes into strong contact with the dresser or the work piece, the rotating grindstone will bite into the dressing surface or the grinding surface. However, it was necessary to gradually perform it while requiring considerable skill. Therefore,
It was difficult to automate, but recently, in order to automatically reduce the feed speed that brings the rotating grindstone closer to the dresser or the work piece, when the rotating grindstone contacts the dresser or the work piece, a load is applied to the rotating grindstone. Therefore, a speed adjusting method is generally adopted in which a change in current generated at this time is detected and the feed speed is changed based on the detection signal.

[0003]

By the way, this method operates by a change in electric current, and this change can be detected only when the rotary grindstone is brought into contact with the workpiece and is pressed to some extent. Regarding this point, according to the results of experiments conducted by the inventor, the feed speed of the rotary grindstone becomes low when the dresser or the workpiece comes into contact with the rotary grindstone and is dressed or ground by about 30 μ. For this reason, there has been a problem that the rotary grindstone bites into the dresser or the work piece to cause polishing burn. Also,
In the case of dressing, the amount of dressing was large, so that the whetstone was consumed significantly. From these points, it is necessary to reduce the feed rate of the rotary grindstone before the contact with the workpiece, but such fine adjustment is difficult, and therefore there is a problem that the feed time becomes long and the work efficiency decreases. It was

[0004]

The present invention has been made in view of the above points, and the invention according to claim 1 is a hollow and waterproof property formed by bending a rubber hose, a vinyl tube, or the like. An acoustic guide (11), a piezoelectric element (10c) arranged at a base end portion of the acoustic guide to generate a voltage when subjected to ultrasonic vibration, and a matching material provided on an end surface of the piezoelectric element on a tip end side of the acoustic guide. (1
0b), a discrimination circuit (12b) that receives an output signal from the ultrasonic sensor (10) and outputs only a signal in a specific frequency band, and an output of the discrimination circuit. When a preset reference value is exceeded, a comparison circuit (12c) that outputs a signal to that effect, and based on the output of this comparison circuit, the moving speed and movement of the table (6) on which the rotary grindstone is placed. A movement control unit (7, 8) for determining a distance, and a tip portion of the acoustic guide toward a contact point between a contact object, which is one of a workpiece, a dresser, and a reference stand, and the rotary grindstone. Is disposed in close proximity to the non-contact state so that the state immediately before the contact between the rotating grindstone and the contact object can be detected based on the output of the ultrasonic sensor. With the contact state detection method of the grindstone That. The invention according to claim 2 is
It is a contact state detection device of a rotary grindstone using the above method. In the present invention, the dresser also includes a rotary dresser.

[0005]

[Operation] When grinding a dress or a work piece, if the rotating grindstone is rotated and brought close to the dresser or the work piece, ultrasonic waves of a weak level will vary depending on the surface of the grindstone and the state of the coolant liquid. Vibration is occurring. In the present invention, the tip of the acoustic guide is arranged close to the contact point between the contact object and the rotating grindstone, and since the ultrasonic sensor having a sharp directivity can be configured, the rotating grindstone contacts the contact point. It is possible to increase the output of the ultrasonic sensor as described above. Therefore, by setting the reference value of the comparison circuit to an appropriate weak value, the state immediately before the contact between the rotary grindstone and the contact object can be detected based on the output of the ultrasonic sensor. When the rotating grindstone contacts the contact object, the output of the ultrasonic sensor rises sharply, so if the reference value of the comparison circuit is set to a relatively small value, the moment of contact between the rotating grindstone and the contact object will be It can also be detected.

[0006]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a contact state detecting device using the method for detecting the contact state of a rotary grindstone according to the present invention.
In FIG. 1, reference numeral 1 is a grinding machine, which holds a workpiece 3 for holding a workpiece 2, a table 6 on which a motor 5 for rotating a rotary grindstone 4 is mounted, and a table 6 for moving the table 6 back and forth with respect to the holder 3. The stepping motor 7 is provided, and the motor 7 receives a control signal from the control circuit 8 and adjusts the speed at which the table 6 is sent to the holder 3.

Reference numeral 9 denotes an aerial ultrasonic sensor for detecting an ultrasonic wave emitted from a portion where the workpiece 2 and the rotary grindstone 4 face each other. The sensor 10 and the acoustic guide 11 are provided, and the holder 3
It is located near. As shown in FIG. 2, the sensor 10 has a case 10a in which a matching material 10b made of foamed ceramic is housed in the front part, and a piezoelectric element 10c which generates a voltage when subjected to ultrasonic vibration is arranged in the rear part. There is.
The lead wires of the coaxial cable 9a connected to the feed rate adjusting means 12 described later are connected to the terminals 10d and 10e of the piezoelectric element 10c, and the detection voltage is amplified by the amplifier 12
It is designed to output to a. Further, one end 11a of the acoustic guide 11 formed of a rubber hose, a vinyl tube or the like is fitted around the outer periphery of the case 10a. The other end 11b of the acoustic guide 11 is directed to the contact point between the work 2 and the rotary grindstone 4, and a sensor for ultrasonic waves emitted when the rotary grindstone 4 approaches or contacts the work 2 without influence of disturbance. While being led to 10, the central portion is bent so as to prevent water, grindstone powder, grinding powder, etc. from entering the sensor 10.

Reference numeral 12 is a feed rate adjusting means for finely adjusting the feed rate of the rotary grindstone, and is constituted by an amplifier 12a, a discrimination circuit 12b, a comparison circuit 12c, a photo coupler 12d and the like. The amplifier 12a amplifies the detection signal sent from the aerial ultrasonic sensor 9 and supplies it to the discrimination circuit 12b. In addition, this discrimination circuit 12b is usually 4
The detection signal in the range of 0 kHz to 1 MHz is extracted only at the frequency of about 200 kHz which is hardly affected by the disturbance,
The output signal is supplied to one input of the comparison circuit 12c. A reference voltage is led to the other input of the comparison circuit 12c, and when the reference voltage is exceeded, a signal voltage is applied from the output to the photocoupler 12d. The photocoupler 12d is composed of a photodiode and a phototransistor, receives the signal voltage and gives an output signal from which unnecessary components are removed to the control circuit 8, and the control circuit 8d
Is configured to output a control signal for reducing the rotation speed of the stepping motor 7.

Next, the operation will be described. First, when the work 2 is ground, the holder 3 and the table 6 are separated from each other, and the work 2 is mounted on the holder 3 and the rotary grindstone 4 is mounted on the motor 5. Next, the motor 5 is driven to rotate the rotary grindstone 4, and the stepping motor 7 is activated. At this time, the stepping motor 7 is
The rotation speed is adjusted based on a control signal from the control circuit 8, and the table 6 is controlled so as to approach the holder 3 after starting. Then, when the table 6 approaches the holder 3 and the work 2 and the rotary grindstone 4 approach each other, the rotary grindstone 4
An ultrasonic wave is generated between the end surface of the work 2 and the rotation of. Then, this ultrasonic wave is guided to the sensor 10 side via the acoustic guide 11, and the ultrasonic wave is detected. Along with this, a detection signal is output from the sensor 10 and the amplifier 12a
Amplified through and given to the discrimination circuit 12b. The discrimination circuit 12b extracts a frequency in a required region, and the frequency signal is supplied to the comparison circuit. Upon receiving the signal 12c, the comparison circuit converts the signal voltage into the photocoupler 12
It is output to d and driven. Then, this photo coupler 1
The control circuit 8 which receives the output of 2d outputs a control signal for changing the high speed rotation to the low speed rotation to the stepping motor 7 to slow down the feed speed of the table 6. For this reason,
The rotary grindstone 4 contacts the end surface of the work 2 at a low speed, and the grinding start position of the rotary grindstone 4 is determined by the position at which the detection signal is output, and the rotary grindstone is fed by a fixed distance from that position. Unnecessary pressing and cutting are prevented. Further, the movement of the rotary grindstone 4 more than necessary from the time of contact is restricted, and the rotary grindstone 4 does not bite into the work 2 beyond a required distance, so that the occurrence of polishing burn is avoided and the finish of the work 2 becomes difficult. The trouble goes away.

FIG. 3 shows that the other end 11b of the acoustic guide 11 of the aerial ultrasonic sensor is directed to the position where the rotary grindstone 4 and the dresser 20 are close to each other when the rotary grindstone 4 is close to the dresser 20. Thereby, the ultrasonic wave when the rotary grindstone 4 approaches the dresser 20 is detected, and the dresser start position is determined based on the position where the ultrasonic wave is detected. Other configurations are the same as those described in FIG. FIG. 4 shows a case where the rotary grindstone 4 is dressed by the rotary dresser 30, and the basic configuration is the same as that described in FIG. FIG. 5 shows a case where the reference position of the rotary grindstone is determined, and shows a method of determining the reference position of the rotary grindstone when the rotary grindstone is controlled by the NC control board. That is, the aerial ultrasonic sensor is installed so as to face the proximity position between the reference platform 40 and the rotary grindstone 4, and the ultrasonic wave generated when the rotary grindstone 4 approaches the reference platform is detected as the reference position of the rotary grindstone. To decide. Accordingly, the reference position can be determined without directly contacting the rotating grindstone with the reference base.

[0011]

As described above, according to the present invention, the moment when the rotary grindstone comes into contact with the workpiece or immediately before that can be detected. Therefore, the disadvantage that the rotary grindstone comes into deep contact with the workpiece for determining the grinding start position is solved. Therefore, the grinding speed can be increased until the grindstone comes into contact with the workpiece or the like. Therefore, the time required for the grinding process can be significantly shortened, and the work efficiency can be significantly improved. Further, since the rotating grindstone can be brought into contact with the work surface at a low speed, the problem that the grindstone bites into the work surface and burns the grindstone is prevented, and the finish of the work is improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a feed rate adjusting device for a rotary grindstone according to the present invention.

FIG. 2 is a sectional view of an aerial ultrasonic sensor.

FIG. 3 is a schematic view showing an embodiment of the second invention.

FIG. 4 is a schematic diagram showing an embodiment of the third invention.

FIG. 5 is a schematic view showing an embodiment of the fourth invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Machine tool 2 Work (work) 4 Rotating grindstone 6 Table 7 Motor (movement control part) 8 Control circuit (movement control part) 10 Ultrasonic sensor 10c Piezoelectric element 10b Matching material 11 Acoustic guide (11) and 12b Discrimination circuit 12c comparison circuit

Claims (4)

[Claims] 1. A hollow and waterproof acoustic guide (1) formed by bending a rubber hose, a vinyl tube or the like.
1), a piezoelectric element (10c) arranged at the base end of the acoustic guide and generating a voltage when subjected to ultrasonic vibration, and a matching material (10b) provided on the end surface of the piezoelectric element on the tip side of the acoustic guide. And a discrimination circuit (1) that receives an output signal from the ultrasonic sensor (10) and outputs only a signal in a specific frequency band.
2b), a comparison circuit (12c) that outputs a signal to that effect when the output of this discrimination circuit exceeds a preset reference value, and a rotary whetstone is placed based on the output of this comparison circuit. And a movement control unit (7, 8) for determining the movement speed and movement distance of the table (6), and the contact point between the contacting object, which is either a workpiece, a dresser, or a reference stand, and the rotating grindstone. Toward the front, the tip of the acoustic guide is arranged in close proximity to the non-contact state , and the state immediately before the contact between the rotary grindstone and the contact object
Also can be detected based on the output of the ultrasonic sensor
A method for detecting the contact state of a rotating grindstone, characterized by 2. A hollow and waterproof acoustic guide (1) formed by bending a rubber hose, a vinyl tube or the like.
1), a piezoelectric element (10c) arranged at the base end of the acoustic guide and generating a voltage when subjected to ultrasonic vibration, and a matching material (10b) provided on the end surface of the piezoelectric element on the tip side of the acoustic guide. And a discrimination circuit (1) that receives an output signal from the ultrasonic sensor (10) and outputs only a signal in a specific frequency band.
2b), a comparison circuit (12c) that outputs a signal to that effect when the output of this discrimination circuit exceeds a preset reference value, and a rotary whetstone is placed based on the output of this comparison circuit. And a movement control unit (7, 8) for determining the movement speed and movement distance of the table (6), and the contact point between the contacting object, which is either a workpiece, a dresser, or a reference stand, and the rotating grindstone. Toward the front, the tip of the acoustic guide is arranged in close proximity to the non-contact state , and the state immediately before the contact between the rotary grindstone and the contact object
Also can be detected based on the output of the ultrasonic sensor
Contact state detecting device for a rotary grindstone, characterized in that the. 3. The matching material (10b) is made of foam ceramic, and the movement controller (7, 8) receives the output of the comparison circuit via a photocoupler (12d). The contact state of the rotary grindstone according to Item 1.
Detection method. 4. The matching material (10b) is made of foam ceramic, and the movement controller (7, 8) receives an output of the comparison circuit via a photocoupler (12d). Item 2. A contact state detecting device for a rotating grindstone according to Item 2.