JP3417423B2 - Contact detection device - Google Patents

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, some grinding machines use an AE (Acoustic Emission) sensor as a contact detection device for detecting the position of the grinding surface of a grinding wheel during truing or grinding. A contact detection device using this AE sensor is equipped with a detection pin incorporating the AE sensor on a fixed part such as a headstock, and the grindstone is moved forward in the same manner as when grinding or truing to grind a rotating grinding wheel. The surface is brought into contact with the detection pin, the elastic wave generated at the detection pin at this time is detected by the AE sensor, and the contact of the grinding wheel is determined from the level of the signal output from the AE sensor. The surface position of the grinding wheel is detected from the position of the grinding wheel head at the time of determination.

[0003]

In order to detect the grindstone surface position during this grinding, the same conditions as during grinding are used.
This is done by rotating the grinding wheel and injecting coolant.
For this reason, the coolant ejected from the nozzle and entrained around the grinding wheel is applied to the detection pin, an elastic wave is generated in the detection pin due to the collision pressure of the coolant, and the elastic wave is detected by the AE sensor, so that the grinding wheel contacts. It may be mistakenly judged as. Therefore, conventionally, a method of detecting the surface position of the grindstone by stopping the supply of the coolant has been adopted. Therefore, it takes a preparation time (about 30 seconds) from when the coolant supply stop button is pressed until the coolant is completely stopped, which lengthens the detection cycle and also affects the grinding cycle or the truing cycle. .

In order to solve this, the elastic wave generated in the AE sensor is sampled in synchronization with the rotation of the grinding wheel,
For example, the surface of the grinding wheel is divided into 128 angular phases by sampling 128 times for each rotation of the grinding wheel, and elastic waves are continuously generated at the same position (angular phase) of the grinding wheel. A method has been devised for detecting the contact between the grinding wheel and the detection pin by detecting. However, this method has the following problems depending on the state of the grindstone.

In a state where the surface of the grindstone is conspicuous as after truing, that is, in a grindstone composed of a bond and abrasive grains, when the abrasive grains protrude from the bond on the surface of the grindstone, the detection pin is When it comes into contact with the whetstone, that is,
When one abrasive grain on the surface of the grindstone comes into contact with the detection pin, the abrasive grain comes into contact with the detection pin for each rotation of the grinding wheel, so that elastic waves are generated in the same phase. On the other hand, in the state where the grindstone surface is smooth after grinding the workpiece, that is, when the abrasive grains hardly protrude from the bond on the grindstone surface, even if the detection pin comes in contact with the grindstone, it is elastic in the same phase. Waves are less likely to occur. Therefore, since the contact is detected by generating the elastic wave of the same phase only at the position where the grindstone cuts the detection pin by a certain amount (about several μm), there is a problem that the detection pin is worn.

The present invention is intended to solve the above-mentioned problems, and an object of the present invention is to provide a contact detection device capable of quickly detecting the contact between a grinding wheel and a detection pin regardless of the state of the surface of the grinding wheel. .

[0007]

In order to solve the above-mentioned problems, in the first aspect of the present invention, the detection member 16 with which the rotating detection object 9 is in contact with the detection member 16 is detected while the detection object 9 is rotating. When contacting the member 16, the detection member 1
6, an elastic wave detecting means 20 for detecting an elastic wave generated and outputting an electric signal, and a cycle in which the electric signal from the elastic wave detecting means 20 corresponds to a predetermined fraction of one rotation of the detected object 9. Sampling means 2 for extracting data representing contact / non-contact of the detected object 9 by sampling with
If the data representing the contact between the detected object 9 and 2a and the detected object 9 rotates a predetermined number of times becomes larger than a preset amount, the contact between the detected object 9 and the detection member 16 will occur. And a contact determination means 22f for determining that

Further, in the second aspect of the present invention, the detecting member 16 with which the rotating detected object 9 comes into contact, and the detecting member 16 when the detected object 9 comes into contact with the detecting member 16 while rotating. An elastic wave detecting means 20 for detecting an elastic wave generated in 16 and outputting an electric signal, and a cycle in which the electric signal from the elastic wave detecting means 20 corresponds to a predetermined fraction of one rotation of the detected object 9. Sampling means 22a for extracting data representing contact or non-contact of the detected object 9 by sampling with, and data representing contact of the extracted detected object 9 during one rotation of the detected object 9 are stored in advance. If it is determined that the amount of contact data is larger than the set amount, and the contact data is larger than the set amount continuously over the predetermined number of rotations of the detected object 9, the detected object 9 and the detection member 16 are detected. With Characterized by comprising a contact determination unit 22f to determine that touch.

[0009]

With the above structure, in the first aspect of the present invention, the elastic wave generated in the detection member 16 by the contact of the rotating detection object 9 such as a grinding wheel and the collision of the coolant is detected by the elastic wave detecting means 20. It is detected and output as an electric signal. Data representing contact or non-contact of the detected object 9 by sampling the electric signal from the elastic wave detection means 20 at a period corresponding to a predetermined fraction of one rotation of the detected object 9 by the sampling means 22a. To extract. Then, the contact determination means 22f detects the detected object 9 and the detection member when the data representing the contact of the detected object 9 extracted during the predetermined rotation of the detected object 9 becomes larger than a preset amount. It is judged that 16 has contacted. Further, in the second aspect, the contact determination means 22f determines whether or not the data representing the extracted contact of the detected object 9 in one rotation of the detected object 9 is larger than a preset amount. It is determined that the detected object 9 and the detection member 16 are in contact with each other when more data than the set amount occurs continuously over a predetermined number of rotations of the detected object 9.
Therefore, the surface of the detected object 9 becomes smooth and the detection member 1
Even if contact with 6 makes it difficult to generate a signal in the same phase, contact detection can be performed based on the number of data representing contact regardless of the phase.

[0010]

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 structure of the grinding machine will be described with reference to FIG. The grinding machine 1 has a bed 2, and 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 rotated by a servo motor 4 and the servo motor 4. Lead screw (not shown)
Is moved in the Z-axis direction by. A headstock 5 and a tailstock 6 are installed on the work table 3 so as to face each other, and between the headstock 5 and the tailstock 6, a chuck provided on a spindle 5a of the headstock 5 is provided. Both ends of the workpiece W are supported by 5b and a center 6a provided on the tailstock 6.

In FIG. 2, the grindstone 7 is installed on the bed 2 so as to be movable in the X-axis direction perpendicular to the moving direction of the work table 3, and is fixed to the bed 2 by a servo motor 8 and the servo. It is moved in the X-axis direction by a feed screw (not shown) rotated by the motor 8. The encoder 14 attached to the servomotor 8 is configured to detect the position (or movement amount) of the grinding wheel base 7 from the number of rotations thereof. An inverter motor 30 is attached to the grindstone base 7,
A grinding wheel 9 for grinding the workpiece W is attached, and the driving force of the inverter motor 30 is
Is transmitted from the pulley 32 attached to the pulley 36 to the pulley 36 on the grinding wheel 9 side via the belt 34, and the grinding wheel 9 is rotated. This grinding wheel 9 has a grinding wheel cover 10
And a coolant nozzle 11 is arranged on the exposed side facing the work table 3,
The coolant nozzle 11 is connected to the coolant supply pipe 12. A truing device 15 is attached to the headstock 5 so as to face the grindstone base 7.

Next, the mechanism for detecting the rotation time per rotation of the grinding wheel 9 of this embodiment will be described. A rotation detection sensor 38 is attached to the side of the pulley 36 on the grinding wheel 9 side shown in FIG. A signal generator 40 for generating an optical signal is attached to a side portion of the pulley 36 as shown in FIG. 1, which schematically shows the pulley 36 in FIG. The rotation of 36 causes the signal generator 40 to pass in front of the rotation detection sensor 38, and again counts pulse signals until the signal generator 40 passes in front of the rotation detection sensor 38, and this count value is the grinding wheel. The rotation detection sensor 38 outputs the rotation time per rotation of the vehicle 9.

Next, a mechanical mechanism for detecting the grinding surface position of the grinding wheel 9 of this embodiment will be described. As shown in FIG. 2, the detection pin 16 is attached to detect the surface position of the grinding wheel 9, and the detection pin 16 is, as shown in FIG. It is fixed at 5. In addition, this detection pin 16
An AE sensor head (elastic wave detection means) 18 that detects elastic waves generated when the wheels contact the surface of the grindstone and when the coolant hits is integrally attached.

Here, the principle of the contact detection device of the present embodiment detecting the contact with the grindstone based on the output of the AE sensor head 18 will be described with reference to FIG. In the contact detection device of this embodiment, the output from the AE sensor head 18 is synchronized with the rotation of the grinding wheel 9 to perform sampling. here,
Sampling is performed 128 times for each rotation of the grinding wheel 9. That is, the rotation time per one rotation of the grinding wheel 9 is sampled at a sampling cycle divided into 128. As a result, the outer peripheral surface of the grinding wheel 9 is 360 ° / 128 = 2.8.
An AE that is sampled by dividing into 125 ° angle phases and corresponds to each 2.8125 ° angle phase of the grinding wheel 9.
The output of the sensor head 18 is obtained. The grinding wheel 9 has relatively large irregularities on the outer peripheral surface in a conspicuous state (in a grindstone composed of a bond and abrasive grains, the abrasive grains protrude from the bond on the surface of the grindstone), and is located at the outermost position. A contact signal of the AE sensor head 18 is generated when the abrasive grains contacting the detection pin 16. The contact signal corresponding to the abrasive grains is generated in the same angular phase no matter how many times the grinding wheel 9 is rotated. On the other hand, it is very unlikely that the signals generated by the collision of the coolant with the detection pin 16 are generated in the same angular phase. Therefore, in the contact detection device of the present embodiment, when the output of the AE sensor head 18 sampled so as to correspond to the same angle phase over a plurality of rotations, that is, the same angle phase occurs over 16 rotations of the grinding wheel 9. Judge as contact with.

On the other hand, when the surface of the grinding wheel 9 is smooth, relatively large irregularities do not exist on the outer periphery (a state in which a large number of abrasive grains almost uniformly protrude from the bond on the surface of the grinding wheel). Even in this state, when the detection pin 16 actually contacts the grinding wheel 9, it is difficult to obtain the output of the AE sensor head 18 at the same angular phase due to the abrasive grains that have largely protruded as described above, but it slightly protrudes almost uniformly. It is possible to obtain the output of a large number of AE sensor heads 18 by the innumerable abrasive grains. Therefore, in the first embodiment of the present invention, there is an elastic wave in a quarter or more of the 128 sampled outputs of the AE sensor head 18 obtained during one revolution of the grinding wheel 9, and this state is the grinding wheel. When the wheel 9 continues for three rotations, it is determined that the grinding wheel 9 contacts the detection pin 16. In addition, here, the elastic wave generated by the coolant impact may occupy nearly a quarter of the whole when the contact is judged only when the elastic wave is present in a quarter or more of one rotation. This is because it is known from experience. Also, 3
In addition to the coolant, there is a requirement that the rotation is continuously generated, which exists on the surface of the grinding wheel 9, or
This is because an elastic wave may be generated by the foreign matter contained in the coolant, and the elastic wave due to the foreign matter and the elastic wave due to the coolant may be superimposed to instantaneously exceed the quarter. That is, due to such a situation, one rotation is 4 times as described above.
This is because even if it exceeds one-third, there is almost no possibility that this situation will continue for three revolutions.

Further, the configuration and operation of the contact detection device will be described with reference to FIG. In FIG. 1, the contact detection device includes an AE sensor amplifier 20 that shapes and outputs an elastic wave signal (electrical signal) detected by the AE sensor head 18, and a grinding wheel 9 based on the output from the AE sensor amplifier 20. And a computer 22 for judging contact with the detection pin 16. When the computer 22 determines contact, a contact detection signal is output to the CNC 26 side that controls the grinding machine 1.

The AE sensor amplifier 20 includes a high-pass filter 20a for extracting only an elastic wave component from a detection signal output from the AE sensor head 18, and a rectifying circuit 20b for full-wave rectifying the elastic wave signal passing through the high-pass filter 20a. And a smoothing circuit 20c for smoothing this rectified signal
And an amplifier 20d for amplifying the smoothed signal.

If the detection pin 16 is brought into contact with a convex portion on the outer peripheral surface of the grinding wheel 9 or if a coolant that circulates with the grinding wheel 9 is applied to the detection pin 16, a collision pressure between the convex portion on the outer peripheral surface of the grinding stone and the coolant is generated. The corresponding elastic wave is detected by the detection pin 16
This elastic wave is detected by the AE sensor head 18. The elastic wave signal output from the AE sensor head 18 is the high-pass filter 20a of the AE sensor amplifier 20.
3A, only the elastic wave signal S1 having a waveform as shown in FIG. 3A is extracted from the high-pass filter 20a and output to the rectifier circuit 20b. In the rectifier circuit 20b, the elastic wave signal S1 is full-wave rectified into the waveform shown in FIG. 3B and output to the smoothing circuit 20c. The smoothing circuit 20c smoothes the full-wave rectified waveform shown in FIG. 3 (b) to output the signal S2 having the waveform shown in FIG. 3 (c).
This signal S2 is amplified by the amplifier 20d and output to the computer 22 side.

On the other hand, on the computer 22 side, each time a sampling pulse is applied to the gate circuit 22a from the sampling pulse generating circuit 22b, the output from the AE sensor amplifier 20 is passed to the comparator 22d side. The sampling pulse generation circuit 22b applies a sampling pulse to the gate circuit 22a so that sampling is performed 128 times during one rotation of the grinding wheel 9. The sampling cycle of the sampling pulse generation circuit 22b is set by the setter 22c so as to be synchronized with the rotation of the grinding wheel 9. The setter 22c adjusts the sampling period of the sampling pulse generation circuit 22b when the rotation speed of the grinding wheel 9 is changed. In other words, in the grinding machine, the rotation speed of the grinding wheel is switched and used appropriately based on the accuracy required for the workpiece, etc. Therefore, even if the rotation speed of the grinding wheel 9 is arbitrarily set, The sampling period of the sampling pulse generating circuit 22b is adjusted by operating the setting device 22c so as to maintain synchronization with the sampling period.

The comparator 22d compares the output sampled by the gate circuit 22a with the threshold value set in the threshold value setting circuit 22e, and when the sampled output is higher than the threshold value, "1" is digitally output to the CPU 22f side as "1" as high AE sensor data, and conversely, "0" is low as low AE sensor data. The CPU 22f holds the AE sensor data “1” or “0” corresponding to each angular phase of the grinding wheel 9 in the memory 22g.

Control information of the CPU 22f is stored in the memory 22g, and the "1" and "0" signals are stored in the form of a mask shown in FIG. This mask conceptually explains the AE sensor data stored in the memory 22g. The vertical column shows at what rotation the grinding wheel 9 was acquired, and the horizontal column shows It represents the order of sampling data in the rotation. In other words, the sampling number in the horizontal column indicates the correspondence between the grindstone outer periphery (angular phase) and the sampled number, for example, “1” in the horizontal column,
“2” and “3” respectively indicate the angular phase of the grinding wheel 9 “0 °
~ 2.8125 ° "," 2.8125 ° -5.625 "
”, And AE at“ 5.625 ° to 8.4375 ° ”
The output of the sensor head 18 (AE sensor data) is shown. The contact determination process based on the AE sensor data by the CPU 22f will be described in detail later.

Next, an outline of the position detecting operation of the surface of the grindstone by the contact detecting apparatus of the present embodiment having the above-mentioned structure will be described with reference to FIGS. 1 and 2. During grinding or truing, position detection is performed when 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 is detected. First, the grinding wheel 9 is rotated by the inverter motor 30 in the same manner as during truing or grinding, and the CNC 26 moves the workpiece table 3 in the Z-axis direction by the servomotor 4 to detect the pin 16.
Is positioned at a position directly facing the grinding wheel 9. Next, the contact detection process is started. First, in order to synchronize the sampling cycle of the sampling circuit 21 with the rotation of the grinding wheel 9, the rotation time per one rotation of the grinding wheel 9 is measured. A sampling cycle in which the rotation time per rotation is 1/128 is set. Then, the servo motor 8
Is driven to move the whetstone base 7 stepwise toward the detection pin 16 side. The outer peripheral surface of the grinding wheel 9 is the detection pin 16
When the contact detection signal indicating that the contact is made is received from the computer 22 side of the contact detection device, the advancement of the wheel head 7 is stopped and the position at this time is detected by the encoder 14 attached to the servo motor 8. Then, the grindstone base 7 is moved backward by fast forward.

Next, the contact detection process between the grinding wheel 9 and the detection pin 16 by the elastic wave from the AE sensor head 18 will be described with reference to FIGS. 1, 2 and 4 based on the flow chart shown in FIG.

First, the CNC 26 applies a forward command pulse to the servo motor 8 every 0.5 seconds to move the wheel head 7 forward toward the detection pin 16 side by one pitch (1 μm). The grinding wheel 9 is configured to rotate 32 times (that is, repeat 16 times twice) when the grinding wheel base 7 advances by one pitch. At the same time, the CNC 26 also gives an activation signal to the computer 22 side. As a result, the determination step 51 in the flowchart shown in FIG. 5 becomes Yes, and the CPU 22f of the computer 22 determines in step 52 the comparator 22 based on the elastic wave signal from the detection pin 16 described above.
The AE sensor data by d is stored in the memory 22g as data as shown in FIG. Then, when the storage of this data is completed for 16 revolutions of the grinding wheel 9, the judgment step 53 becomes Yes, and the routine proceeds to the next judgment step 54. In the determination step 54, it is determined whether the AE sensor data are aligned for 16 cycles (16 rotations) in the same phase, as described later. Here, when 16 cycles are aligned in the same phase, the determination step 54 becomes Yes and step 56
Then, the CPU 22f sends a contact detection signal to the CNC 26 side. As a result, the CNC 26 determines the position of the grindstone surface based on the output of the encoder 14 attached to the servomotor 8 and stops the forward movement of the grindstone base 7 to prevent subsequent detection pin 16 wear.

On the other hand, if the determination step 54 is NO, the process proceeds to a determination step 55 to further determine whether the number of AE sensor data is a certain amount or more. When the number of AE sensor data is a certain amount or more, the determination step 55 is Yes.
In step 56, the CPU 22f sends a contact detection signal to the CNC 26 side. On the other hand, if the number of AE sensor data is less than the fixed value, the above determination step 55 becomes No, and the process returns to step 52 and the AE for the next 16 cycles.
Enter the sensor data.

Here, in the determination as to whether the AE sensor data in step 54 are aligned for 16 cycles in the same phase, the data as shown in FIG. 4A is obtained because the grinding wheel 9 stands out immediately after truing. As obtained, it will be described in more detail with reference to the flowchart of FIG.

First, in step 61, the CPU 22f initializes a variable n, which indicates how many times the grindstone was sampled in one revolution, to 1. Further, in step 62, the number of revolutions of the grindstone, that is, the variable m representing the number of revolutions in 16 revolutions is initialized to 1. Then, in this state, the process proceeds to the determination step 63, and whether or not there is the first sampled AE sensor data in the first rotation, that is, whether the elastic wave signal from the detection pin 16 is "1" or " Judge whether it is "0". Here, as shown in FIG. 4 (A), the first step of the first rotation is “0”, so the judgment step 63
Becomes No, and the process proceeds to the determination step 67. In the judgment step 67, the sampling number (variable) n is 128.
To judge. Here, since n is 1, the determination step 67 becomes No and the routine proceeds to step 68. In step 68, 1 is added to n to change the sampling number for judgment to "2". Then, the process proceeds to the determination step 63 via the step 62, and it is determined whether or not there is the second sampled AE sensor data in the first rotation. Here, since the second value of the first rotation is "1", the determination step 63 becomes Yes and the process proceeds to the determination step 64.

In the judgment step 64, m + 1, that is,
The second sampled A for the second rotation
E Determine whether or not there is sensor data. Here, since the second value of the second rotation is also "1", the determination step 64 becomes Yes and the process proceeds to the determination step 65. In the decision step 65, it is confirmed whether m is 16, that is, the decision is made for all 16 revolutions. Here, since m is 1, the determination step 65 becomes No and the process proceeds to step 66. Then, in step 66, 1 is added to m to change the target rotation number to "2". And decision step 6
Returning to step 4, it is determined whether or not there is m + 1, that is, the second sampled AE sensor data for the third rotation. Here, since the second value of the third rotation is also "1", the process proceeds to the judgment step 65. Even if the processing from determination step 64 to step 66 is repeated for 16 cycles, if the determination step 64 continues to be Yes, that is, the AE sensor data has the same phase (here, the second sampled AE sensor data) 16 times. When the cycles are complete, the judgment step 65 becomes Yes (B in the figure (proceeds to the step 56 side of the contact detection signal ON shown in FIG. 5))
Move to.

On the other hand, when the grinding wheel 9 repeatedly grinds the workpiece, the AE sensor data is not conspicuous and the 16 phases are not aligned in the same phase as shown in FIG. 4B. The processing in step 54 will be described with reference to the flowchart in FIG. In the processing of the judgment step 63, the CPU 22f first judges whether or not there is the first sampled AE sensor data in the first rotation ("1" or "0"). Here, the first
Judgment step 67 because the first rotation is "0"
Move to. In the judgment step 67, it is judged whether the sampling number (variable) n is 128. Here, since n is 1, the process proceeds to step 68. In step 68, 1 is added to n to change the sampling number for judgment to "2", and in judgment step 63, the second rotation of the first rotation is performed.
The decision is made on the AE sensor data sampled the second time. If the above processing is performed up to the 128th sampled data, that is, for all data, AE
It is determined that the sensor data does not have the same phase for 16 cycles, and the determination step 67 becomes Yes, and the process proceeds to C in the figure (proceeding to the processing on the determination step 55 side shown in FIG. 5).

Continuing on, in the determination step 55 of the flow chart shown in FIG. 5 described above, in the determination as to whether the number of AE sensor data is a certain amount or more, the case where the AE sensor data shown in FIG. An example will be described in detail with reference to the flowchart of FIG. 7.

First, in step 71, the CPU 22f initializes a variable m representing the number of revolutions of the grindstone, that is, the number of revolutions in 16 revolutions, to 1. Then, in step 72, the m-th
(1) The number of AE sensor data for the rotation is calculated. That is,
All the numbers of “1” of the first rotation shown in FIG. 4 (B) are added up. Here, it is assumed that the number of “1” is “12”. Next, in the judgment step 73, it is judged whether the number of AE sensor data is 32 or more, that is, whether the number of AE sensor data is 1/4 or more of 128 corresponding to all the sampling numbers. Here, the determination step 73 is No, and the process proceeds to the determination step 79. In decision step 79, m = 14, that is, 14
Check if the judgment is completed up to the rotation. In this case, the determination step 79 becomes No and the process proceeds to step 80, 1 is added to the variable m, the determination target is advanced to the second rotation, and step 7 is performed.
Return to 2.

In step 72, the number of AE sensor data for the second rotation is calculated. Here, it is assumed that the number of AE sensor data is "44". Therefore, the next judgment step 73 becomes Yes and the routine proceeds to step 74. Step 74
Then, the value of the variable q is set to the value of the variable m, which is 2 here. Next, at step 74, 1 is added to the value of the variable q to be 3. Then, the process proceeds to step 76, and the number of AE sensor data for the qth rotation, that is, the third rotation, which is the second rotation after the second rotation, is calculated. Here, it is assumed that the number of AE sensor data is “12”. Therefore, the determination step 77 becomes No and the process proceeds to the determination step 79, and the same processing as described above is repeated.

Here, in step 72, the first
It is assumed that the number of AE sensor data is “44” when the number of AE sensor data of the fourth rotation is calculated. Therefore, the next judgment step 73 becomes Yes and the routine proceeds to step 74. In step 74, the value of the variable q is set to the variable m, here 1
4 and further, in step 75, 1 is added to the value of q to be 15. Then, the process proceeds to step 76, and the number of AE sensor data for the qth rotation, here the 15th rotation corresponding to the 14th rotation, is calculated. Here, the number of AE sensor data is "4.
3 ". Therefore, the judgment step 77 becomes Yes and the routine proceeds to the judgment step 78. In this judgment step 78, q = m + 2, that is, three or more laps of 1/4 or more of the number of AE sensor data. It is determined whether or not it has continued, but since it is a state in which two revolutions of the 14th rotation and the 15th rotation have continued, this determination is No, the process returns to step 75, and 1 is added to the variable q to be 16. In step 75, the number of AE sensor data at the qth rotation, that is, the 16th rotation is calculated, and it is assumed that the number of AE sensor data is “44.” Therefore, determination step 77 becomes Yes and determination step 78 Here, the determination of q = m + 2 in the determination step 78 is made because the quarter or more of the number of AE sensor data is 14 rotations, 15 rotations, 16 rotations and 3 rotations in succession. Yes, and (go to Step 56 side of the contact detection signal ON shown in FIG. 5 process) number B in is made Figure determining the predetermined amount or more of the AE sensor data
Move to.

On the other hand, when the processing is advanced to the 14th rotation without the number of times the number of AE sensor data is 1/4 or more continues for 3 times, m in the above-mentioned judgment step 79 is 14
If the determination is Yes, it is determined that the AE sensor data is less than a certain amount, and D (step 5 shown in FIG. 5) in the figure is determined.
Return to the process on the side 2). As described above, in the above-described embodiment, step 54 is performed before step 55. Therefore, when the grinding wheel 9 is conspicuous after truing, the grinding wheel 9 must be cut deeply with respect to the detection pin in step 5
Where the contact signal of 4 is not output, the signal of step 55 is output by just making a slight cut, so that the detection pin 16 is less worn.

Next, a second embodiment of the present invention will be described. The mechanical structure of the contact detection device according to the second embodiment and the processing of the elastic wave signal are substantially the same as those in the above-described first embodiment, and the description thereof will be omitted. However, the determination process in the determination step 55 of the flowchart shown in FIG. 5 whether the number of AE sensor data is a certain amount or more is different. Therefore, the processing of the judgment step 55 will be described with reference to the flowchart of FIG.

First, in step 81, AE for 16 rotations is performed.
The number of sensor data is calculated, that is, all the numbers of “1” for 16 rotations of the AE sensor data shown in FIG. 4 are added. Then, in the judgment step 82, the AE for this 16 rotations
Whether the number of sensor data is 1/4 or more of the whole, that is, 16
It is determined whether × 128 ÷ 4 = 512 or more. Where AE
When the number of sensor data is 1/4 or more, it is determined that the AE sensor data is a certain amount or more, and the determination step 82 becomes Yes (B in FIG. 5 (step 56 shown in FIG. 5 side). Proceed to processing). On the other hand, when the number of the AE sensor data is less than 1/4, it is determined that the AE sensor data is less than the fixed amount, and the determination step 82 is No (D shown in FIG. 5 (step shown in FIG. 5)). Return to the processing on the 52 side).

In the above-described embodiment, 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 head 18, and whether the elastic wave signal is generated in the same phase by the CPU 22f is first checked. When it is determined and this state is confirmed, the grinding wheel 9 detects the detection pin 1
It is judged that 6 has been contacted. That is, the contact signal generated when the convex portion of the outer peripheral surface of the grinding wheel 9 comes into contact with the detection pin 16 as described above when the grinding wheel 9 is conspicuous is the same angle for each rotation of the grinding wheel 9. It occurs in phase. On the other hand, the signals generated by the coolant impinging on the detection pin 16 are very unlikely to be generated in the same angular phase. Therefore, even if the coolant hits the detection pin 16 and an elastic wave is generated, the contact with the grindstone can be detected without erroneous detection.

On the other hand, when the grinding wheel 9 is inconspicuous, it is difficult to generate an elastic wave signal in the same phase, and if the grinding wheel 9 is continuously fed until the elastic wave signal in the same phase is generated, the detection pin of several μm is detected. 16 is advanced by the grinding wheel 9, but in the present embodiment, the contact between the grinding wheel 9 and the detection pin 16 is determined depending on whether the AE sensor data is 1/4 or more. The contact can be detected when 16 is ground, and the wear of the detection pin 16 can be minimized.

In the first embodiment, the number of revolutions to be continuously detected for contact determination is set to 3 times, but this number can be set to any number as long as it is 2 or more. Further, when the AE sensor data of 1/4 or more is determined to be contact, this value can be appropriately set based on the actual operation of each grinding machine. In addition, in the second embodiment, the number of AE sensor data for all 16 rounds is added, but the number of rotations for which this addition is performed can be any number of rotations such as one round. Further, in the above-described embodiment, the contact detection of the grinding wheel has been described as an example, but the contact detection device of the present invention can also be applied to the contact detection of an object to be detected other than the grinding stone.

[0041]

According to the present invention, the contact between the grinding wheel and the AE sensor can be detected quickly regardless of the condition of the surface of the grinding wheel, and the wear of the detection pin can be minimized.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a contact detection device according to an embodiment 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 a waveform diagram showing output waveforms at various parts of the contact detection device shown in FIG.

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

FIG. 5 is a flowchart showing the entire processing of contact determination in the present embodiment.

FIG. 6 is a flowchart showing a process of determining whether the outputs of the flowchart shown in FIG. 5 are aligned in the same phase.

FIG. 7 is a flowchart showing a process for determining whether the number of AE sensor data in the flowchart shown in FIG.

FIG. 8 is an AE of the contact detection device according to the second embodiment of the present invention.
It is a flow chart which shows the judgment processing of whether the number of sensor data is more than a fixed quantity.

[Explanation of symbols]

1 grinder 9 grinding wheel 16 detection pins 20 AE sensor amplifier 22 Computer 22a gate circuit 22d comparator 22f CPU 26 CNC

Front page continuation (72) Inventor Shigeo Hotta 1-1 Asahi-cho, Kariya city, Aichi Toyota Koki Co., Ltd. (56) Reference JP-A-6-114693 (JP, A) Patent 3168485 (JP, B2) Patent 3119330 (JP, B2) Patent 3119331 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) B23Q 17/22 B24B 49/10

Claims (2)

(57) [Claims] 1. A detection member with which a rotating detection object comes into contact, and an elastic wave generated in the detection member when the detection object rotates and comes into contact with the detection member, and outputs an electric signal. And an electric signal from the elastic wave detecting means for detecting the detected object.
Sampling means for extracting data representing contact or non-contact of the detected object by sampling at a cycle corresponding to a predetermined fraction of rotation; and the extracted detected object during a predetermined number of rotations of the detected object. A contact detection device comprising: contact determination means for determining that the detected object is in contact with the detection member when the amount of data representing the contact of the object exceeds a preset amount. 2. A detection member with which a rotating detection object contacts, and an elastic wave generated in the detection member when the detection object rotates and contacts the detection member, and outputs an electric signal. And an electric signal from the elastic wave detecting means for detecting the detected object.
Sampling means for extracting data representing contact / non-contact of the detected object by sampling at a cycle corresponding to a predetermined fraction of rotation, and a sampling means for extracting the detected object during one rotation of the detected object. It is determined whether or not the data representing the contact is larger than a preset amount, and if the contact data is larger than the set amount continuously over a predetermined number of rotations of the detected object, the detected object is detected. And a contact determination means for determining contact with the detection member.