JPH06114692A - Contacting sensing device - Google Patents

Abstract

PURPOSE:To sense certainly the contacting of a sensing member with any object to be sensed such as a grinding wheel irrespective of the noise component. CONSTITUTION:The elastic wave of a sensing pin 16 generated with contacting of a grinding wheel 9 or bombardment with coolant is sensed by an AE sensor 18, and the elastic wave signal emitted by the AE sensor 18 and having a level over the specified is converted into a rectangular signal by a rectangular wave producing circuit 20. The resultant rectangular signal is sampled at certain intervals by a sampling circuit 21, and thereby the data in an amount corresponding to a plurality of cyclic periods representing contacting/out of contacting of the grinding wheel 9 is extracted at every angle phase corresponding to the sampling interval and taken into a signal processing circuit 22. This circuit 22 judges that the grinding wheel 9 is contacting the sensing pin 16 when it acknowledges, from the data taken in, data representing contacting continuously in the same phase and for a plurality of periods.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact detecting device used in a grinding machine for detecting the surface position of a grinding wheel during truing or grinding.

[0002]

2. Description of the Related Art Conventionally, in a grinding machine, as a contact detecting device for detecting the grinding surface position of a grinding wheel at the time of truing or grinding, a detection pin incorporating an AE (Acoustic Emission) sensor such as a headstock is used. It is attached to the fixed part and the grinding head of the rotating grinding wheel is brought into contact with the detection pin by advancing the grindstone head forward during grinding or truing, and elastic waves generated at this time are detected by the AE sensor. The contact of the grinding wheel is determined from the level of the signal detected and output from the AE sensor, and the surface position of the grinding wheel is detected from the determination signal and the forward feed amount of the grinding wheel head.

[0003]

By the way, when detecting the position of the grindstone surface during grinding, in order to make the conditions similar to those during grinding, when the coolant ejected from the nozzle hits the detection pin, it is detected by the collision pressure of the coolant. An elastic wave may be generated in the pin, and the elastic wave may be erroneously determined to be in contact with the grindstone by being detected by the AE sensor.

Therefore, conventionally, a method of stopping the supply of the coolant and detecting the surface position of the grindstone has been adopted. However, even if such a method is taken, when the coolant remaining in the pipe and the nozzle is dropped on the detection pin, the elastic wave generated by the dropping pressure may be erroneously detected as being in contact with the grindstone. . In order to solve this, the contact of the grindstone is detected after the coolant remaining in the pipe and the nozzle is removed by air. However, such a method requires a preparation time (about 30 seconds) until the contact detection of the grindstone is required, which results in a long detection cycle time and also has an influence on a grinding cycle or a truing cycle. It was

The present invention solves the above-mentioned problems, and the contact of the detection member with the object to be detected such as a grindstone is influenced by the noise component even if the detection member is sprayed with the coolant. It is an object of the present invention to provide a contact detection device capable of surely detecting without contact.

[0006]

The present invention will be described with reference to FIG. 1 which is one embodiment. In the present invention, the detection member 16 with which the rotating detection object 9 is brought into contact, and the detection object 9 are provided. An elastic wave detecting means 18 for detecting an elastic wave generated in the detecting member 16 when it comes into contact with the detecting member 16 while rotating, and outputting an elastic wave signal; and the elastic wave detecting means 1.
Rectangular wave generating means 20 for shaping and outputting the elastic wave signal of a predetermined level or higher output from 8 into a rectangular wave signal, and the sampling by sampling the output signal from the rectangular wave generating means 20 at a predetermined interval. Sampling means 21 for extracting one cycle of data representing contact or non-contact of the detected object 9 for each angular phase corresponding to the interval, and a plurality of cycles of the extracted one cycle of data, and based on the data It is provided with a signal processing means 22 for determining the contact between the detected object 9 and the detection member 16 when the data representing the contact is recognized in the same angular phase and continuously over a plurality of cycles.

[0007]

With the above structure, the detection member 1 is provided by contact with the rotating detection object 9 such as a grindstone or the collision of the coolant.
The elastic wave generated at 6 is sequentially converted into a rectangular wave signal by the rectangular wave generation means 20. Then, these rectangular wave signals are sampled by the sampling means 21 to extract a plurality of cycles of data representing contact and non-contact corresponding to one cycle of the detected object 9 and fetched into the signal processing means 22. The signal processing unit 22 determines the contact of the detected object 9 when the data representing the contact having the same phase and continuously over a plurality of cycles is recognized from the captured data. Therefore, the contact between the detected object 9 and the detection member 16 can be surely detected without being influenced by the random noise component generated regardless of the sampling cycle.

[0008]

Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 is an overall configuration diagram of a contact detection device according to the present invention, and FIG. 2 is a schematic plan view of a grinding machine to which the contact detection device of the present invention is applied.

First, the configuration of FIG. 2 will be described. In FIG. 2, reference numeral 1 is a grinder having a bed 2. A work table 3 is installed on the bed 2 so as to be movable in the Z-axis direction. The work table 3 is moved in the Z-axis direction by a servo motor 4 and a feed screw (not shown) rotated by the servo motor 4. Be moved to.

A headstock 5 and a tailstock 6 are positioned on the left and right sides of the workpiece table 3 so as to face each other. Between the headstock 5 and the tailstock 6, a spindle 5a of the headstock 5 is provided. Both ends of the workpiece W are supported by a chuck 5b provided at the center and a center 6a provided at the tailstock 6.

In FIG. 2, reference numeral 7 denotes a grindstone head mounted on the bed 2 so as to be movable in the X-axis direction perpendicular to the moving direction of the workpiece table 3. The grindstone head 7 is a servo fixed to the bed 2. The motor 8 and a feed screw (not shown) rotated by the servo motor 8 move the motor 8 in the X-axis direction. The grindstone base 7 has a grindstone wheel 9 for grinding the workpiece W. The grindstone wheel 9 is covered by a grindstone cover 10, and a coolant nozzle 11 is provided on the exposed side facing the worktable 3. The nozzle 11 is provided and is connected to the coolant supply pipe 13.

Reference numeral 14 is an encoder for detecting the amount of movement of the grinding wheel base 7 from the number of rotations of the servo motor 8. Further, 15 is a truing device which is attached to the headstock 5 so as to face the grindstone 7, and 16 is a detection pin for detecting the surface position of the grinding wheel 9. As shown in FIG. It is fixed to the headstock 5 facing the grindstone base 7 by a support member 17. Further, the detection pin 16 is integrally attached with an AE sensor 18 for detecting an elastic wave generated at the time of contact with the surface of the grindstone and by the collision of the coolant.

Next, the configuration of FIG. 1 will be described. In FIG. 1, the contact detection device is a rectangular wave generation circuit 20 that shapes each elastic wave signal having a predetermined level or higher detected by the AE sensor 18 into a rectangular wave and outputs a rectangular wave signal corresponding to the duration of the elastic wave. And N per wheel wheel revolution (eg 25
Sampling pulse generation circuit 21a that generates 6) sampling pulses in synchronization with the rotation of the grinding wheel, and a gate circuit 21b that gates each time the sampling pulse is applied to sample and output the output signal of the rectangular wave generation circuit 20. The sampling signal of the rectangular wave generation circuit 20 sampled by the sampling circuit 21 and the sampling signal of the rectangular wave generation circuit 20 are fetched and subjected to predetermined signal processing, whereby contact between the grinding wheel 9 and the detection pin 16 is performed. It is composed of a signal processing circuit 22 for determining the presence or absence.

The rectangular wave generation circuit 20 includes a high-pass filter 20a for extracting only the elastic wave component from the detection signal output from the AE sensor 18, and the high-pass filter 20a.
Circuit 20b for full-wave rectifying the elastic wave signal passing through
And a smoothing circuit 20c for smoothing this rectified signal, and the smoothed signal and the reference signal are compared, and while the level of the smoothed signal exceeds the reference signal level, the output is set to the high level and the elasticity is set. And a comparator 20d that sends out a rectangular wave signal according to the wave signal.

The signal processing circuit 22 has an interface 22a for receiving the sampling signal of the rectangular wave generating circuit 20 passing through the gate circuit 21b every time it is gated by a sampling pulse, and an outer peripheral surface of the grinding wheel 9 taken in through this interface 22a. The CPU 22b determines whether or not the grinding wheel 9 is in contact with the detection pin 16 based on the sampling signals corresponding to the respective angular phases, and the memory 22c that stores the sampling signals processed by the CPU 22b.

Next, the operation of this embodiment configured as described above will be described. When detecting the position of the grindstone surface corresponding to the grinding surface of the grinding wheel 9 with respect to the workpiece W or the truing device 15 during grinding or truing, first, the workpiece table 3 is moved to Z by the servomotor 4.
By moving in the axial direction, the detection pin 16 is positioned at a position directly facing the grinding wheel 9. In this state, the grinding wheel 9 is rotated in the same way as during truing or grinding, and the coolant is jetted from the nozzle 11. Further, the servomotor 8 is rotationally controlled by a command signal from a numerical control device (not shown) to advance the grindstone base 7 stepwise to the detection pin 16 side, and the outer peripheral surface of the grinding wheel 9 comes into contact with the detection pin 16. If is detected, the forward feed of the grindstone base 7 is stopped, and after a predetermined time, the grindstone base 7 is retracted by fast-forward.

When the projection on the outer peripheral surface of the grinding wheel 9 comes into contact with the detection pin 16 or when the coolant ejected from the nozzle 11 is sprayed onto the detection pin 16, the projection on the outer peripheral surface of the grindstone and the spraying force of the coolant. A corresponding elastic wave is generated in the detection pin 16, and this elastic wave is detected by the AE sensor 18. When the elastic wave signal output from the AE sensor 18 is input to the high-pass filter 20a of the rectangular wave generation circuit 20, the high-pass filter 20a outputs a signal shown in FIG.
Only the elastic wave signal S1 having a waveform as shown in (a) is extracted and output to the rectifier circuit 20b.

In the rectifier circuit 20b, the elastic wave signal S1 is output.
Full-wave rectified to the waveform shown in 3 (b) and output to the smoothing circuit 20c.
I will be forced. In the smoothing circuit 20c, the full wave shown in FIG.
By smoothing the rectified waveform, the wave shown in FIG.
The signal S2 of the shape is output. This smoothed signal S2 is
When input to the comparator 20d, the comparator 20d
Smoothing signal S2 and reference signal V_refCompare with and smooth
Signal S2 is reference signal V _refFor a period exceeding the level
By setting the output of the palletizer 20d to the H level,
As shown in (d), the width depends on the duration of the elastic wave signal.
A rectangular wave signal S3 is generated.

On the other hand, the sampling pulse generating circuit 21a
When the sampling pulse SP of is applied to the gate circuit 21b, the gate circuit 21b moves N times per one rotation of the grindstone.
For example, it is gated 256 times, and the output signal of the rectangular wave generation circuit 20 is sampled for each gate and output to the signal processing circuit 22. The number of times the sampling pulse SP is generated per unit time can be freely changed by manual operation,
Since the rotation speed of the whetstone is known, 2
It is adjusted so that the sampling pulse SP is generated 56 times.

In the CPU 23b of the signal processing circuit 22, the sampling signals sequentially fetched are associated with the angular phase of the grinding wheel 9 corresponding to the sampling interval and stored in the memory 22c.
To store.

FIG. 4 shows how the sampling signal is stored in the memory 22c. In FIG. 4, the numbers 1 to N represent N per revolution of the grindstone, for example, the sampling position (angular phase) with respect to the grindstone outer peripheral surface corresponding to a sampling interval of 256 times, and "1" represents the sampled output of the comparator 20d. Indicates that it is in the "H" state, and "0" indicates the sampled comparator 2
This means that the output of 0d is in the "L" state.

Data that exceeds n revolutions of the grindstone is, for example, n +
Data for one rotation is stored at the first rotation, and at the same time, data for n + 2 rotations is stored at the second rotation. The memory 22c stores the contact determination program shown in the flows of FIGS. A at step 100
= 1 is set, it is determined in step 101 whether A is “1” for n rotations, and if NO, it is associated with A in step 102 and stored as “0” in the determination data of the memory 22c, and YES is determined. If there is, it is associated with A in step 103 and stored as "1" in the judgment data of the memory 22c. A is N
Until step 101 is exceeded,
Is repeatedly executed, and the determination data shown in FIG. 7 is created.

When A exceeds N in step 105, the process shown in FIG.
In step 200, A = 1 is set, and in step 201
To set K = 0. The data stored in A of the determination data is read in step 202, and if it is "1", K is incremented to K + 1 in step 203, and step 2 is performed.
In 04, it is determined whether K is m or more. If YES, a contact signal is output, and if NO, the process proceeds to step 205.

If NO at step 202, K is set to 0, and the routine proceeds to step 206.
In step 206, A is incremented to A + 1, and in step 207 it is determined whether A exceeds N. If NO, steps 202 to 207 are repeated. If NO in step 207,
When it is determined that there is no contact signal and the sampling data for one rotation of the grindstone is newly input, the step 100
To step 207 are repeatedly executed.

Since the outer peripheral surface of the grinding wheel 1 has irregularities,
A contact signal is generated when the convex portion comes into contact with the detection pin 16, and the contact signal corresponding to the convex portion is generated at the same angular phase no matter how many rotations the grinding wheel 9 makes.
On the other hand, the signals generated by the coolant impinging on the detection pin 16 are unlikely to occur in the same angular phase.

Therefore, in association with the phase of the grinding wheel, the AE
As shown in FIG. 4, the sensor 18, that is, the sampling signals “1” and “0” of the rectangular wave signal are fetched from the first rotation to the nth rotation (16th rotation) of the grinding wheel 9 into the memory 22c. From the sampling signal pattern in the memory, it is determined whether or not the sampling signal of "1" is standing at the same angular phase and continuously for n rotations. If this state is recognized, the grinding wheel 9 is set to the detection pin 18. Judge that it has contacted. In the embodiment shown in FIG. 4, it is indicated that the grindstone comes into contact with the detection pin at the phase portions of numerals 6 and 7.

In this embodiment as described above, the elastic wave of the detection pin generated by the contact of the grindstone and the collision of the coolant is detected by the AE sensor, and the elastic wave signal output from the AE sensor at a predetermined level or higher is rectangular. The wave generation circuit converts the signal into a rectangular wave signal, and the output signal of the rectangular wave generation circuit is sampled by N pulses per one rotation of the grindstone and taken into the signal processing circuit. Sampling signals sequentially taken in by the signal processing circuit. Is stored in the memory in association with the angular phase of the outer peripheral surface of the grinding wheel, and it is determined from this memory whether there is a sampling signal of "1" that has the same phase and is continuous for n revolutions. When this state is recognized Since it is determined that the grinding wheel is in contact with the detection pin, coolant is sprayed onto the detection pin when detecting the position of the grinding wheel surface. Even so the elastic wave generated by this by eliminating the erroneous detection of the grindstone contact, it is possible to reliably detect contact with the grindstone. With this,
It is possible to detect contact with the grindstone under the same conditions as when grinding while ejecting the coolant, and without the need to stop the coolant supply and eliminate the cycle of removing residual coolant in the pipes and nozzles by air as in the past. Therefore, the detection cycle time can be shortened.

In the above embodiment, the contact detection of the grinding wheel has been described, but the present invention is not limited to this, and can be applied to the contact detection of an object to be detected other than the grinding wheel. Further, the present invention is not limited to the configuration shown in the above embodiment,
Various modifications can be made without departing from the scope of the claims.

[0029]

As described above, according to the present invention, the elastic wave generated in the detection member when the detection object rotates and comes into contact with the detection member is detected by the elastic wave detecting means.
After the elastic wave signal output from the detecting means is converted into a rectangular wave signal, the rectangular wave signal is sampled at a predetermined interval so that a contact or non-contact of the object to be detected is made at each angular phase corresponding to the sampling interval. Is extracted for a plurality of cycles, and the contact between the detected object and the detection member is determined when the data representing the contact with the same phase and continuously over a plurality of cycles is recognized from this data. Therefore, it is possible to reliably detect the contact of the detected object without being influenced by the noise component.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of a contact detection device of the present invention.

FIG. 2 is a schematic plan view of a grinding machine provided with the contact detection device of the present invention.

FIG. 3 is an explanatory diagram showing an output waveform of each unit in the present embodiment.

FIG. 4 is an explanatory diagram showing an example of storing a sampling signal used for contact determination in a memory in the present embodiment.

FIG. 5 is a flow chart used for contact determination in the present embodiment.

FIG. 6 is a flowchart used for contact determination in the present embodiment.

FIG. 7 is an explanatory diagram showing an example of storage of determination data used for contact determination in a memory in the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 grinder 7 grindstone 9 grindstone (object to be detected) 11 coolant nozzle 16 detection pin (detection member) 18 AE sensor (elastic wave detection means) 20 rectangular wave generation circuit (rectangular wave generation means) 21 sampling circuit (sampling means) ) 22 Signal processing circuit (signal processing means)

Claims (1)

[Claims] 1. A detection member with which a rotating detection object contacts, and an elastic wave signal generated by detecting an elastic wave generated in the detection member when the detection object rotates and contacts the detection member, and outputs an elastic wave signal. An elastic wave detecting means for outputting; a rectangular wave generating means for shaping the elastic wave signal output from the elastic wave detecting means to a rectangular wave signal and outputting the rectangular wave signal; and an output signal from the rectangular wave generating means. Sampling means for extracting one cycle of data representing contact or non-contact of the detected object for each angular phase corresponding to the sampling interval by sampling at a predetermined interval, and a plurality of cycles of the extracted one cycle of data A signal processor for determining the contact between the object to be detected and the detection member when the data representing the contact is recognized based on the captured data and the same angular phase and continuous over a plurality of cycles based on the data. A contact detection device comprising: a step.