JPS6127151B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a processing device such as a plasma processing machine, a laser processing machine, or an electron beam processing machine, especially a processing device having a function of controlling the distance between a torch or focus adjustment means and a workpiece to a constant value. This invention relates to improvements in processing equipment.

Generally, when processing a workpiece with a gas cutting machine, the distance between the torch and the workpiece must always be kept constant, but the surface of the workpiece is not necessarily flat and may have undulations, distortion, etc. Some of them are large, and this becomes a major factor in changes in arc length, leading to deterioration in processing quality. Therefore, in the conventional case, the arc voltage between the torch and the workpiece was detected and the distance between the torch and the workpiece was automatically adjusted. To explain this point using Figure 1,
The arc voltage generated between the torch 2 and the workpiece 3 by the power supply of the cutting machine 1 is compared with the set voltage of the set voltage source 5 by the comparator amplifier 4, and the control circuit 6 controls the motor based on the difference voltage. A drive device 7 of various types is driven. This drive device 7 is a vertical movement holder 9
Torch 2 via support 8 by driving
to raise or lower. In other words, the control device 6 moves the torch 2 up and down so that the error signal that is the output of the comparator amplifier 4 becomes zero, and the torch 2 and the workpiece 3
Always maintain a constant distance between

However, in the case of such conventional devices that detect the arc voltage and control the distance between the torch and the workpiece to be constant, the arc voltage changes due to fluctuations in the distance between the torch and the workpiece. Not only
There is a drawback that the distance cannot be precisely controlled to a constant value because it varies depending on fluctuations in the power supply voltage of the processing machine, changes in the type and flow rate of gas, and also depending on the acceleration to be processed and the thickness of the workpiece. This tendency is particularly strong in plasma processing machines, and there is a problem in that conventional control mechanisms cannot be applied to laser processing machines that require extremely accurate control.

The present invention obviates the drawbacks of such prior art devices by converting changes in the distance between the torch or focusing means and the workpiece into changes in the high frequency voltage between the sensing conductor and the workpiece, The present invention is characterized in that the distance between the torches or focus adjustment means is always maintained constant by moving the torch or focus adjustment means up and down using a drive signal that changes depending on changes in the high frequency voltage.

An embodiment of the present invention will be explained with reference to FIG. In the figure, 10 is a circular metal detection ring arranged so that the torch 2 is located in the center, 11 is a support rod for the detection ring 10, and 12 is a rod that moves the detection ring 10 up and down within a certain range. 13 is a first high frequency signal source that outputs a sinusoidal high frequency voltage of, for example, 40KHz; 14 is a support that fixes the support rod 11 to the torch 2 so as to obtain 15 is a capacitance formed between the workpiece 3 and the detection conductor 10; 16 is a capacitor connected between the detection conductor 10 and ground;
17 is a capacitor connected in series with the first high frequency signal source 13, 18 is a coupling capacitor, 19 and 20 are protection resistors, 21 is a variable capacitor for height adjustment, and 22 is a voltage in a desired frequency band. A bandpass filter 22a for passing a signal, an error amplifier 22b, a protection element 22c formed by connecting diodes in antiparallel, and a phase control capacitor 2.
2d, etc., 23 is a variable resistor for signal level adjustment, 24 is an amplifier, 25 is amplifier 2
An inverter 26 and 27 invert the phase of the voltage signal from 4, and a sampling pulse generation circuit 26 and 27 that alternately generate sampling pulses of mutually opposite phase in synchronization with the outputs of the first and second high frequency signal sources 13 and 14, respectively. , 28 and 29 are sampling circuits, respectively; 30 is an integration circuit that integrates and holds the voltage signals from the sampling circuits 28 and 29, and whose integrated value is cleared by a clearing pulse from the sampling pulse generation circuit 26; 31; ,32
33 and 34 are signals from the rising signal generating circuit 31 and falling signal generating circuit 32, respectively, which generate a rising signal and a falling signal depending on the magnitude of the integral holding signal from the integrating circuit 30. 35 and 36 are speed regulators.

Next, the operation of the apparatus having such a configuration will be explained. For example, the first and second high frequency signal sources 13, 1
The output voltage of 4 is 180 as shown in Figure 3A and B, respectively.
゜It is a sine waveform with a phase shift, and the high frequency signal source 1
The peak-to-peak value of the AC output voltage of 3 is
13.2V _pp , and the peak-to-peak value of the AC output voltage of the high frequency signal source 14 is selected to be 6V _pp . The detection ring 10 is set at approximately the same level as the lower surface of the torch 2, or at a position slightly lower than the lower surface of the torch 2.

When the first and second high-frequency signal sources 13 and 14 are activated with the torch 2 located above the workpiece 3, the connection point a of the capacitors 16 to 18 is connected to the detection ring 10 and the workpiece. An alternating voltage E _a of 40 KHz appears whose amplitude depends on the value of the capacitance 15 between the objects 3 . Here, the capacitance 15 is
It is based on a capacitor that uses the detection ring 10 and the workpiece 3 as electrodes and the air between them as a dielectric, and as the distance between the detection ring 10 and the workpiece 3 increases or decreases, the capacitance 15 decreases or increases. do. Therefore, the peak value of the AC voltage E _a at point a depends on the capacitance 15, that is, the distance between the detection ring 10 and the workpiece 3, and this AC voltage E _a is applied via the coupling capacitor 18 and the protective resistor 20. The signal is applied to the inverting terminal of the operational amplifier 22b and the bandpass filter 22a in the combining circuit 22. On the other hand, the second high frequency signal source 14 has the same frequency as the output of the first high frequency signal source 13 (40KHz).
A high frequency voltage E _b as shown in FIG. 3B having an opposite phase, that is, a phase shift of 180 degrees, is sent to the inverting terminal of the operational amplifier 22b in the synthesis circuit 22 and the bandpass filter 22a via the variable capacitor 21 for height adjustment. Give it to the input terminal. The combining circuit 22 outputs a combined signal E _c corresponding to the difference between the two AC voltages E _a and E _b , and the phase of this combined signal E _c changes depending on the change in the capacitance 15 as shown in FIG. 3C. advance or lag behind. This composite signal E _c is the variable resistance 2
3, its magnitude is adjusted to become E _c ′, and this composite signal E _c ′ is amplified by an amplifier 24 and directly applied to the sampling circuit 28 on the one hand, and its phase is inverted by an inverter 25 on the other hand. The signal is applied to the sampling circuit 29. The sampling pulse generation circuits 26 and 27 alternately generate sampling pulses as shown in FIGS.
29 respectively. Therefore, sampling circuit 2
8 and 29 are the third
An integration circuit 30 samples the output signal of the amplifier 24 and its inverted output signal as shown in FIGS.
As a result, the integrating circuit 30 integrates a signal as shown in FIG.

Now, as mentioned above, the signal shown in FIG. The phase changes as shown. For example, when the distance D between the detection ring 10 and the workpiece 3 is a set distance (for example, 6 mm), the third
Since the voltage-time products of the positive and negative voltage waveforms in the signal shown in FIG. H are equal, the output of the integrating circuit 30 becomes zero level.

Next, when the distance D between the detection ring 10 and the workpiece 3 becomes larger than 6 mm, the capacitance 15 becomes smaller, and as a result, the voltage waveform in FIG. It shifts in the direction of , and becomes as shown in Figure I. Also, the distance D between the detection ring 10 and the workpiece 3 is 6 mm.
When the capacitance 15 becomes smaller, the capacitance 15 increases, and as a result, the voltage waveform shown in FIG.

Therefore, the integrating circuit 30 produces a zero level, positive or negative level DC voltage signal depending on whether the distance D between the detection ring 10 and the workpiece 3 is equal to, greater than, or less than the set length. The integrated value of each cycle of this integrating circuit 30 is held for the next one cycle, and then, at the rising edge of the clearing pulse from the sampling generator 26, the integrated value of each cycle of the first high frequency signal source 13 is cleared. The output of the integrator circuit 30 is therefore equal to the maximum integral value of the immediately previous cycle.

Rising signal generation circuit 31, falling signal generation circuit 32
outputs a rising signal or a falling signal depending on whether the output level of the integrating circuit 30 is positive or negative. Upon receiving this rising signal or falling signal, the rising drive circuit 33
Alternatively, the down drive circuit 34 provides a rise drive signal or a fall drive signal to a drive device 7, such as a motor, via respective speed regulators 35,36. The drive device 7 drives the vertically movable holder 9 upward and downward according to the upward drive signal or downward drive signal so that the distance D between the detection ring 10 and the workpiece 3 is always at the set length. Adjust the height of torch 2. Here, the speed adjustment by the speed regulators 35 and 36 is performed manually.

According to one embodiment of the processing apparatus according to the present invention described above, the following effects can be obtained.

(1) Changes in capacitance that depend on the distance between the detection ring and the workpiece are converted into a high-frequency signal voltage, and this signal voltage automatically adjusts the distance between the torch and the workpiece to the set length. As a result, even with a small detection ring, the distance between the torch and the workpiece can be automatically adjusted to the set length with great precision.

(2) During processing, noise in a wide frequency range up to very high frequencies appears on the detection ring due to the plasma arc, laser, or beam, but this noise can be significantly removed by the capacitance 15 and capacitor 16, so noise countermeasures can be taken. is relatively easy.

(3) A synthesis circuit synthesizes a first high-frequency voltage that depends on the capacitance between the detection ring and the workpiece and a second high-frequency voltage that has the same frequency as this high-frequency voltage and has a substantially opposite phase. A phase-modulated signal corresponding to the capacitance between the detection ring and the workpiece is obtained, and the height between the detection ring and the workpiece is automatically adjusted using a drive signal related to this signal, so noise can be avoided. This makes the height adjustment of the detection ring even more precise.

In addition, although the detection conductor was explained as a detection ring in the above description, the detection conductor is not limited to this.
It may be a half ring or a rod-shaped ring, or a plurality of rings may be used. In addition, as an example, a processing machine that uses a torch is shown, but of course a laser processing device, an electron beam processing device, etc. may also be used, and in this case, a focus adjustment means such as an optical lens or an electrostatic lens and a detection conductor are used. As described above, by automatically adjusting the distance between the detection conductor and the workpiece to keep it constant, the distance between the focus adjustment means and the workpiece can be kept constant. As a result, even if the workpiece has irregularities, the density of machining energy applied to the workpiece surface can always be kept constant.

[Brief explanation of the drawing]

Fig. 1 is a diagram for explaining a conventional processing device using a torch, Fig. 2 is a diagram showing an embodiment of the processing device according to the present invention, and Fig. 3 shows waveforms of various parts in Fig. 2. It is a diagram. 2... Torch, 3... Workpiece, 7... Drive device, 10... Detection conductor, 15... Capacitance between the detection conductor and workpiece, 13, 14... First,
Second high frequency signal source, 20...Synthesizing circuit, 21...
...Bandpass filter, 24...Amplifier, 25...
Inverter, 26, 27...Sampling pulse generation circuit, 28, 29...Sampling circuit, 3
0...Integrator circuit, 31, 32...Rise and fall signal generation circuit, 33, 34...Rise and fall drive circuit,
35, 36...speed regulator.

Claims (1)

[Claims] 1. In a processing device equipped with a mechanism capable of automatically adjusting the distance between a torch or focus adjustment means and a workpiece, a detection device arranged to move up and down together with the up and down movement of the torch or focus adjustment means. a first series connection of a first high-frequency signal source and a capacitor connected in parallel to a variable capacitance formed between the detection conductor and the workpiece; the first series connection; a second series connection body of a height adjustment capacitor connected in parallel to the body and a second high frequency signal source that produces a frequency output that is the same as the output frequency of the first high frequency signal source and is in opposite phase; , a synthesizing circuit that synthesizes a voltage depending on the distance between the detection conductor and the workpiece and a voltage generated by the second high-frequency signal source, an integrating circuit that integrates an output signal from the synthesizing circuit, and an integrating circuit that integrates an output signal from the integrating circuit. A processing device comprising a drive device that moves an adjusting means up and down in response to an output signal.