JPH035404Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a device for detecting contact between a tool and a workpiece in a processing machine, for example, detecting the centering of a workpiece or the starting point of machining in a processing machine. used for.

(Prior Art) Conventionally, it has been known to use an electromagnetic phenomenon caused by contact between a tool of a processing machine and a workpiece as a starting point for processing. However, in general processing machines, the main shaft that supports the tool rotates, so when the main shaft rotates at high speeds, the tool is insulated from the frame by an oil film that forms inside the main shaft bearing, and the tool and workpiece are insulated. contact is relatively difficult to detect. The inventor of the present invention previously proposed an improved device that can detect contact between a tool and a workpiece even under such conditions in a patent application.
It was proposed as No. 60-53010. With this device, even when the main shaft of the processing machine rotates and the bearing becomes insulated due to the oil film, the small loop current flowing to the processing machine is detected through the capacitance that exists there. Therefore, the detection sensitivity is set high (that is, the detection level is low). However, when the main shaft of the processing machine is stopped, it is necessary to detect the contact position between the tool and the workpiece in order to center the workpiece, measure its dimensions, or correct the length and diameter of the tool. arise.
In this case, when the tool and workpiece come close to each other, even if they are not in contact, a certain amount of loop current flows through the processing machine through metal powder or cutting oil attached to the tool or workpiece, so the high-sensitivity There is a problem with this detection device that it may malfunction and lack stability in operation.

(Problems to be solved by the invention) The present invention has been made in view of the above-mentioned problems, and it maintains stable contact between the tool and the workpiece regardless of whether the main shaft of the processing machine is rotating or stopped. The technical means for this purpose is a sensor section that is attached to a processing machine 1 having a rotating main shaft section 3 and electromagnetically detects contact between a tool 4 of the processing machine 1 and a workpiece 5. 6, and a detection unit 20 for obtaining a detection signal indicating contact between the tool and the workpiece from the output signal of the sensor unit, and the detection unit 20 outputs the detection signal at a relatively low detection level. A detection section 22 and a low level determination section 3 that outputs a signal from the low level detection section 22 as a detection signal only when a rotation signal of the main shaft section 3 is present.
4, and a high level detection section 2 with a relatively high detection level.
3.

In addition to the above configuration, a high level determination section 35 outputs the signal from the high level detection section 23 as a detection signal only when there is no rotation signal of the main shaft section 3.
A preferred embodiment is to have the following.

(Example) The present invention will be described below based on an example with reference to the drawings.

In FIG. 1, a processing machine 1 has a main shaft 3 that moves relative to a frame 2, and a tool 4 attached to the main shaft 3 contacts a workpiece 5 to perform processing. In order to detect contact between the tool 4 and the workpiece 5, a detection device consisting of an annular sensor section 6 attached to the main shaft section 3 so as to penetrate therethrough, and a control section 18 is provided.

Referring also to FIG. 2, the sensor section 6 has an annular core 8,1 made of a magnetic material such as ferrite.
An excitation coil 7 and a detection coil 10 each having coils 9 and 12 uniformly wound around the coil 1 are interposed between them, and an annular shielding plate 1 made of a magnetic material such as an iron plate is placed between them.
They are arranged close to each other with 3 in between. More specifically, as the cross section is shown in Figure 3A,
Excitation coil 7, detection coil 10 and shielding plate 13
is housed in an annular casing 14 made of a metal material such as aluminum and having a U-shaped cross section, injected with synthetic resin 15 to fix it, and covered with a cover 16 made of synthetic resin. The excitation coil 7 and the detection coil 10 are designed not to contact the casing 14 for insulation, and the shielding plate 13 is connected to both side walls 14a, 14 of the casing 14.
It is designed so that it does not come into contact with b at the same time. A flange portion 1 for mounting is provided on the outer periphery of the casing 14.
4c is provided and is attached to the processing machine 1 with bolts 17.

As shown in FIG. 2, the control unit 18 includes a power supply unit 19 for passing a high-frequency current through the excitation coil 7, and a detection unit 20 for obtaining a detection signal from the output signal of the detection coil 10. This is housed in a single casing, installed in the control panel of the processing machine 1, and wired. The power supply section 19 is
It consists of an oscillation circuit of several KHz to several hundred KHz, a power amplification circuit, etc., and the frequency and output power can be adjusted.

In FIG. 4, the detection unit 20 includes the detection coil 1
an amplifier 21 that amplifies the output signal S1 of 0 to an appropriate level; a low level detector 22 that outputs a detection signal when the output signal S2 of the amplifier 21 is at a relatively low level; and a low level detection section 22 that outputs a detection signal when the output signal S2 of the amplifier 21 is at a relatively high level. It has a high level detection section 23 that outputs. The low level detection section 22 includes an amplifier 2 whose amplification degree can be adjusted by, for example, a regulator 24a.
4, consists of a wave detector 25, a waveform shaper 26, an integrator 27, and an output section 28, and its operation is based on the output signal S2 of the amplifier 21, as shown in FIG.
is amplified to an appropriate level and detected, and converts signals above a certain level into pulses with a certain waveform, and outputs a detection signal S7 when a certain number of pulses (three in this case) or more continues. do. In FIG. 5, S1, S2, S3, S4, S5, S6
and S7 indicate the signal states of the same reference numerals in FIG. 4 when the main shaft portion 3 is rotating, and indicate the time
The tool 4 and the workpiece 5 come into contact at t ₁ , and at time t ₂
, a state in which the detection signal S7 is turned on and output is shown.

That is, a high frequency current flows through the coil 9 of the excitation coil 7 by the power supply section 19, and a high frequency magnetic field is generated in the core 10. When the tool 4 of the processing machine 1 and the workpiece 5 come into contact, the high-frequency magnetic field generates a high-frequency current H that flows in a loop through the frame 2, the main shaft portion 3, the tool 4, and the workpiece 5, as shown in FIG. A high frequency magnetic field is generated in the core 11 of the sensing coil 10 by the high frequency current H, which induces a high frequency current in the coil 12, which becomes the output signal S1 of the sensing coil 10. This output signal S1 is processed by the low level detection section 22 as described above, and a detection signal S7 is generated.
is output. The integrator 27 is intended to prevent malfunctions due to single-shot noise, but this causes a delay time (t ₂ - _{t 1} ) in the response; however, because the frequency of the power supply section 19 is high, this delay time It is only a small amount, and there is no practical problem. in this way,
When the main shaft section 3 is rotating at high speed, the bearing section is insulated from direct current due to the oil film, but there is a finite value of reactance against high frequencies due to the capacitance of that section. Since a high frequency current H is generated, this is detected as a signal S1 by the detection coil 10, and is greatly amplified by the amplifiers 21 and 24 to produce a detection signal S7.
is obtained.

Next, the high level detection section 23 detects the input signal S
2 is at a higher level than that in the low input detector 22, the detection signal S8 is output, and the amplification degree of the amplifier 29 is set relatively low. Shaper 3
1, the integrator 32, and the output section 33 have the same functions as those of the low level detection section 22. Therefore, the high level detection section 23 outputs the detection signal S8 when the tool 4 and the workpiece 5 come into contact when the spindle section 3 is stopped, and in other cases, for example, when the spindle section 3 is rotating. When the tool 4 is in an insulated state as described above, or when the tool 4 and the workpiece 5 come into contact only through metal powder, cutting oil, etc. and the contact resistance is high even when the spindle 3 is stopped, , the detection signal S8 is not outputted because the detection level is high. On the other hand, since the detection level of the low level detection unit 22 is low as described above, when the spindle unit 3 is stopped, the tool 4 and the workpiece 5 may come into contact with each other through metal powder, cutting oil, etc. may also output the detection signal S7, but these signals S7 and S8
In a device (for example, the processing machine 1) that performs the required processing using the main spindle section 3, the main spindle section 3 is stopped by obtaining the logical product of these signals S7 and S8 and the stop or rotation state signal of the main spindle section 3. Correct signals can be obtained in any state of rotation. An example is shown in FIG. In the figure, a signal S9 is a signal indicating that the main spindle 3 is in a high-speed rotation state, and a signal S10 is a signal indicating that the main spindle 3 is in a high-speed rotation state, and a signal S10 is a signal that indicates that the tool 4 and the workpiece are
This is a detection signal that is output when the object comes in contact with the object.

That is, a low level determination section 34 is provided which performs an AND operation between the signal S7 from the low level detection section 22 and the signal S9 generated when the main shaft section 3 is in a high speed rotation state. The output signal is generated only when the motor is rotating at high speed. On the other hand, a logical negation circuit 36 is provided for the rotation signal S9 of the spindle section 3 so that an output signal is not generated when the spindle section 3 is rotating at high speed, but an output signal is generated when the spindle section 3 is stopped. A high level determining section 35 is provided which performs an AND operation with the signal S8 from the high level detecting section 23, so that the high level determining section 35 generates an output signal only when the main shaft section 3 is stopped. The output signal of the low level determination section 34 and the output signal of the high level determination section 35 are logically summed by an OR circuit 37 and outputted as one of the detection signals S10.

By providing the low level determination section 34 in this way, the main spindle of the processing machine can be stopped even if a minute loop current flows through metal powder or cutting oil attached to the tool or workpiece when the main spindle of the processing machine is stopped. This prevents malfunctions. Further, by providing the high level determining section 35 as described above, there is no possibility of unexpectedly outputting a detection signal when the main shaft rotates at high speed.

According to the above embodiment, when the tool 4 and the workpiece 5 are not in contact with each other, the high frequency current H is applied to the processing machine 1.
does not flow, so no increase in power consumption is caused, and when the tool 4 and workpiece 5 come into contact, a high-frequency current H flows even when the main shaft portion 3 is rotating at high speed, and this is detected by the detection coil 10. Detection is performed without contact, and the detection signal is detected by the detection unit 20 with a good SN.
It can be obtained stably with the ratio. Since the excitation coil 7 and the detection coil 10 are housed in the casing 14 and integrated, installation and replacement are easy. Since the shielding plate 13 is provided, it is possible to reduce the output generated in the detection coil 10 due to the leakage magnetic field from the excitation coil 7. As shown in FIG. 3B, the sensor section 6 includes an excitation coil 7 and a detection coil 1.
0 may be housed in separate casings 27 and 28, respectively, and the detection coil 10 may be mounted apart from each other to the extent that it is not affected by the leakage magnetic field of the excitation coil 7.

In the above embodiment, the detection section 20 has the configuration shown in FIG. 4, but various other configurations are possible. For example, to adjust the detection level, instead of varying the amplification degrees of the amplifiers 24 and 29, the thresholds for outputting pulse signals of the waveform shapers 26 and 31 may be varied. . Furthermore, the integrators 27 and 32 may be configured by synchronous counters, and by inserting an appropriate noise filter or by comparing the signal with the signal from the power supply section 19, signals other than those caused by the high frequency current H can be canceled out. , it is also possible to detect by detecting a change in the phase of the detection signal. It is also possible to use two excitation coils 7 or two detection coils 10 and make them sandwich the other in a sandwich-like configuration to reduce the influence of leakage magnetic fields, increase detection sensitivity, and further improve the signal-to-noise ratio. Flange portion 14 on casing 14
c may be omitted and it may be attached to the processing machine 1 using a separate attachment member made of synthetic resin or metal. If the capacitance of the bearing of the main shaft portion 3 of the processing machine 1 is insufficient or unstable, an annular opposing plate may be provided between the stationary part and the rotating part to face each other without contact to maintain a constant static. The capacitance may be provided separately. The processing machine 1 includes a machine tool, and also includes one in which the main shaft part 3 is fixed and the workpiece 5 moves.
The mounting on the workpiece 5 side should be interpreted as a design modification of the present invention.

(Effects) According to the present invention, contact between the tool and the workpiece can be stably detected even when the main shaft of the processing machine is rotating or stopped. This makes it possible to easily and accurately perform centering and dimensional measurements, dimensional correction of tool length and diameter, and tool defect detection.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a front view showing the detection device installed on a processing machine, FIG. 2 is a perspective view including a partial block diagram of the detection device, and FIG.
Figure A is a cross-sectional view of the sensor part, Figure 3B is a cross-sectional view showing another example of the sensor part, Figure 4 is a block diagram showing an example of the detection part, and Figure 5 is an example of signal waveforms of each part. 6 are circuit diagrams showing an example of processing of the detection signals S7 and S8. H...High frequency current (induced current), S7, S8...
...Detection signal, 1...Processing machine, 2...Frame, 3
...Spindle part, 4...Tool, 5...Workpiece, 6...
Sensor unit, 10...Detection coil, 20...Detection unit, 22...Low level detection unit, 23...High level detection unit, 34...Low level determination unit, 35...High level determination unit.

Claims (1)

[Claims for Utility Model Registration] (1) A sensor section that is attached to a processing machine having a rotating main shaft section and electromagnetically detects contact between a tool of the processing machine and a workpiece, and a sensor section that detects the contact between the tool and the workpiece based on the output signal of the sensor section. The detection unit consists of a low-level detection unit that outputs a detection signal with a relatively low detection level, and a detection unit that outputs a detection signal that outputs a detection signal only when a rotation signal of the main shaft is present. A contact detection device for a tool and a workpiece, comprising a low level determination section that outputs a signal from the low level detection section as a detection signal, and a high level detection section whose detection level is relatively high. (2) The tool and workpiece according to claim 1, which have a high level determination section that outputs a signal from the high level detection section as a detection signal only when there is no rotation signal of the main shaft section. Contact detection device.