JPH11123573A - Method and device for calibration of gap sensor in machining head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize machining precision by automatically detecting that relation between a nozzle gap and an electrical characteristic such as a voltage becomes inaccurate and surely carrying out calibration. SOLUTION: This device detects a gap G from a machining part 21 in the lower part of a machining head 9 to a work W by means of a gap sensor 23 based on a correlation with an electrical characteristic. The detection signal is inputted to a control unit 27 through a sensor controller 25. A change in a movement amt. in the height direction of the machining head 9 moved vertically by a motor 31 is detected by an encoder 33 and inputted to the control unit 27. The correlation between the electrical characteristic value from the sensor controller 25 and the gap G detected from the change in the movement amt. from the encoder 33 is compared with a calibration adjustment value on the basis of a normal correlation between the gap G and the electrical characteristic which is inputted preliminarily to the control unit 27, if an abnormal difference exists, a calibration command is generated from the control unit 27 and the nozzle gap G is always maintained accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing machine, a plasma processing machine, a copying machine, a gas fusing machine, and the like having a gap sensor for detecting a distance between a workpiece such as a nozzle in a processing head and a workpiece. And a device for calibrating a gap sensor in a processing head.

[0002]

2. Description of the Related Art Conventionally, when laser processing is performed by a plate processing machine, for example, a laser processing machine, as shown in FIG. 4, a nozzle 103 provided below a laser processing head 101 and a work W made of a plate material. Preserving the nozzle gap G between them accurately is an important factor for performing stable processing and precision processing of the work W. In order to accurately maintain the nozzle gap G, a gap sensor 105 using electrical characteristics such as capacitance, eddy current, and frequency is provided on the outer periphery of the nozzle 103 and used.

The nozzle gap G is controlled by, for example, detecting a change in capacitance when the distance between the workpiece W and the nozzle 103 changes, by the gap sensor 105, and a change in an electrical characteristic value such as a voltage via the sensor controller 107. Is input to the control device 109. The controller 109 issues a command to perform vertical axis movement of the laser processing head 101 so that the converted voltage always becomes a constant voltage, and controls the nozzle gap G.

When laser processing is performed at a preset nozzle gap G, a calibration adjustment value for clarifying the correlation between the nozzle gap G and the voltage is required. This calibration adjustment is usually
The voltage value for each gap is measured, and the correlation between the nozzle gap G and the voltage is obtained as shown in FIG.

The nozzle gap G is controlled by adjusting the vertical axis of the laser processing head 101 based on the calibration adjustment value so as to have a predetermined voltage value corresponding to the preset nozzle gap G. You.

[0006]

Incidentally, in the prior art, the execution of calibration is usually performed arbitrarily at the start of operation, when the operation of the sensor is not good, or when the type of the nozzle 103 is changed. Many.

However, if the tip of the nozzle 103 is contaminated by sputtering or the like and the shape of the nozzle 103 changes due to an external force due to an operation error or the like due to long-time laser processing, the capacitance of the gap sensor 105 is reduced. Is changed, the nozzle gap G of the calibration adjustment value is changed.
Therefore, there is a problem that it is difficult to accurately maintain the nozzle gap G because the correlation between the pressure and the voltage changes.

As described above, since the calibration is often performed arbitrarily, the calibration operation is not performed frequently, or the calibration is not performed when the type of the nozzle 103 is changed. At times, there have been problems such as the occurrence of processing defects and a reduction in processing accuracy.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to automatically detect that the relationship between a nozzle gap and electrical characteristics such as voltage has become inaccurate, An object of the present invention is to provide a method and an apparatus for calibrating a gap sensor in a processing head that can perform calibration reliably and stabilize processing accuracy of a workpiece.

[0010]

According to a first aspect of the present invention, there is provided a method for calibrating a gap sensor in a machining head according to the present invention, wherein a gap from a machining portion below a machining head to a workpiece is determined by the gap sensor. Detecting based on the correlation with the electrical characteristics, inputting this detection signal to the control device via the sensor controller, and detecting the change in the amount of movement of the processing head in the height direction which moves up and down by the processing head elevating device. The correlation between the electric characteristic value from the sensor controller and the gap detected from the change in the movement amount from the processing head movement amount detection device is controlled in advance by detecting the movement amount by the movement amount detection device and inputting it to the control device. For the calibration adjustment value based on the normal correlation between the gap input to the device and the electrical characteristics, Abnormal difference Te is characterized in by comprising by which the command of the calibration from the control device when there is.

Accordingly, the nozzle gap and the electrical characteristics of the gap sensor are affected by the fact that the tip of the nozzle is contaminated by spatter or the like due to laser processing for a long period of time, or the shape of the nozzle is changed by an external force due to an operation error or the like. Even if the correlation with the value changes, this change is automatically detected and a calibration command is issued from the control device. Therefore, the calibration is automatically performed or the execution of the calibration is performed by an operator. The calibration is surely performed.
Therefore, the nozzle gap is always maintained accurately, so that the workpiece can be stably processed and precisely processed.

According to a second aspect of the present invention, there is provided a calibration apparatus for a gap sensor in a processing head, the gap sensor detecting a gap from a processing portion below a processing head to a workpiece based on a correlation with electrical characteristics. A sensor controller that inputs a detection signal from a gap sensor to a control device, a processing head elevating device that moves the processing head up and down, and a processing head movement amount detection device that detects a change in a movement amount of the processing head in a height direction. ,
Calibration based on the normal correlation between the gap and the electrical characteristics input in advance, the correlation between the electrical characteristic value from the sensor controller and the gap detected from the change in the amount of movement from the processing head movement amount detection device. And a control device for issuing a calibration command when there is an abnormal difference as compared with the adjustment value.

Therefore, the operation is the same as that of the first aspect, and the laser processing is performed for a long time, so that the tip of the nozzle is contaminated by spatter or the like, or the shape of the nozzle is changed by an external force due to an operation error or the like. As a result, even if the correlation between the nozzle gap and the electrical characteristic value of the gap sensor changes, this change is automatically detected and a calibration command is issued from the control device. Performing the calibration or notifying the operator of the execution of the calibration ensures the calibration. Therefore, the nozzle gap is always maintained accurately, so that the workpiece can be stably processed and precisely processed.

According to a third aspect of the present invention, in the apparatus for calibrating a gap sensor in a machining head according to the second aspect of the present invention, the control device is configured to determine an abnormal value for a calibration adjustment value in advance. And a calibration command is issued when the gap detected from the change in the electric characteristic value from the sensor controller and the movement amount from the processing head movement amount detection device exceeds the threshold value. It is characterized by becoming.

Therefore, the control device issues a calibration command when the electric characteristic value from the sensor controller and the gap from the processing head movement amount detection device exceed the threshold value, so that the calibration is performed without fail and the work is performed reliably. Stable processing and precision processing are surely performed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a method and apparatus for calibrating a gap sensor in a processing head according to the present invention will be described with reference to the drawings.

Referring to FIG. 3, for example, a laser processing machine 1 as a plate processing machine according to the present embodiment has a built-in laser oscillator 3 for oscillating a laser beam LB (laser light). Laser beam LB
Is reflected by the laser processing head 9 provided at the tip of the laser beam guide irradiation unit 7 vertically downward via the reflecting mirror 11 via the intensity adjusting device 5. This laser beam LB is condensed by a focusing lens 13 provided inside the laser processing head 9. The laser beam LB is focused on the work W transferred and positioned by, for example, a numerically controlled work transfer positioning device 17 (work transfer device) with respect to the irradiation optical axis 15 of the focused laser beam LB. Then, laser processing such as cutting into a desired shape is performed.

Next, a detailed description will be given of a gap sensor calibrating device 19 showing a main part of the embodiment of the present invention.

Referring to FIG. 1, a nozzle 21 is provided at the tip of the laser processing head 9.
Is provided with a gap sensor 23 for detecting a gap G from the nozzle 21 to the work W based on a correlation with an electrical characteristic such as capacitance. The gap sensor 23 is electrically connected to a control device 27 via a sensor controller 25. The gap sensor 23 may be a sensor utilizing electrical characteristics such as capacitance, eddy current, and operation transformer, and is not particularly limited.

The laser processing head 9 is screwed into a ball screw 29 extending vertically in the main body of the laser processing machine, and the ball screw 29 is driven to rotate by a motor 31 (processing head elevating device). It is provided to be able to move up and down freely. A processing head movement amount detecting device such as an encoder 33 is provided on the rotation axis of the motor 31 to detect a change in the amount of movement of the laser processing head 9 in the vertical direction and measure the position of the laser processing head 9 in the vertical direction. The processing head movement amount detection device is electrically connected to the control device 27.

In the control device 27, the detection signal from the gap sensor 23 and the laser processing head 9 by the encoder 33
The nozzle gap G is controlled based on the detection data of the movement amount of the nozzle. For example, when the gap sensor 23 is a capacitance type sensor, when the distance between the workpiece W and the nozzle 21 changes, the capacitance of the gap sensor 23 changes, and this capacitance changes in the electric characteristic value such as voltage. Is converted to In order to control the nozzle gap G, a calibration adjustment value for clarifying the correlation between the nozzle gap G and the voltage is required,
Normally, a voltage value for each gap is measured as the calibration adjustment value, and a normal correlation between the nozzle gap G and the voltage is obtained as shown in FIG.

In controlling the nozzle gap G, a command is issued from the control device 27 to the motor 31 based on the calibration adjustment value so as to have a predetermined voltage value corresponding to the preset nozzle gap G.
By the operation of 1, the vertical axis movement of the laser processing head 9 is performed and adjusted.

The sensor information input to the control device 27 is not limited to the above-described voltage, but may use electric characteristics such as current and frequency.

The control device 27 is provided with an input device 35 for inputting data, a display device 37, and a memory 39 for storing the input data. A calibration adjustment value based on a normal correlation is stored in the memory 39 in advance.

Further, the control device 27 stores the correlation between the electrical characteristic value from the sensor controller 25 and the gap G detected from a change in the amount of movement from an encoder 33 (a processing head movement amount detecting device). A comparison / judgment device 41 is provided for comparing with a normal calibration adjustment value and issuing a command to automatically execute calibration when an abnormal difference occurs.

For example, if laser processing is performed for a long time,
When spatter or the like adheres to the nozzle 21, when the shape of the nozzle 21 changes due to an external force, or when the type of the nozzle 21 is changed, the correlation between the gap G and the electrical characteristics is shown in FIG. Abnormal 1 or Abnormal 2
It becomes a state like.

The controller 27 receives the information from the sensor controller 25 and the change in the amount of movement of the motor 31 from the encoder 33 when the laser processing head 9 is moved at the start and end of the laser processing. Such a state of abnormality 1 or abnormality 2 is automatically detected, and a command is issued to automatically perform calibration.

The control device 27 issues a warning to a warning device (not shown) so as to notify the operator of the execution of the calibration when the above-mentioned abnormality 1 or 2 is automatically detected. It can also be provided as follows.

In the above example, whether the calibration adjustment value is normal or abnormal is determined when the laser processing head 9 is moved at the start and end of the laser processing. Alternatively, the laser processing head 9 may be moved up and down or during laser processing, and is not particularly limited.

In the above example, an abnormal state is detected with respect to a normal calibration adjustment value. In another example, a large change in electrical characteristics generated when the nozzle 21 is replaced is used. can do.

For example, the capacitance type gap sensor 23
When the cable connecting the gap sensor 23 and the sensor controller 25 is disconnected,
When the nozzle 21 is removed, the capacitance of the gap sensor 23 changes greatly. This change amount is stored in advance in the memory 39 of the control device 27 as a “threshold value”,
When the “threshold value” is reached, the calibration is automatically performed, or the execution of the calibration is notified to the operator. May be provided so as to notify the operator of the instruction of the execution.

As described above, since the calibration is reliably performed, the lower nozzle 21 of the laser processing head 9
The nozzle gap G between the workpiece W and the workpiece W is always accurately maintained, so that the workpiece W can be stably processed and precision processed.

The present invention is not limited to the above-described embodiment, but can be embodied in other modes by making appropriate changes. In this embodiment, a laser processing machine has been described as an example of a plate processing machine. However, a plasma processing machine, a copying machine, a gas fusing machine, and other plate processing machines may be used.

[0034]

As will be understood from the embodiments of the present invention as described above, according to the first aspect of the present invention, if laser processing is performed for a long time, the tip of the nozzle may become dirty by sputtering or the like. Even if the correlation between the nozzle gap and the electrical characteristic value of the gap sensor changes due to a change in the nozzle shape due to external force due to a mistake or the like, this change is automatically detected and the calibration Since the command can be generated, the calibration can be performed automatically, or the execution of the calibration can be notified to the operator, so that the calibration can be performed reliably. Therefore, the nozzle gap can always be accurately maintained, and stable and precise machining of the work can be reliably performed.

According to the second aspect of the present invention, the effect is the same as that of the first aspect. If the laser processing is performed for a long time, the tip of the nozzle may be stained by spatter or the like, or the nozzle may be subjected to an external force due to an operation error or the like. By receiving the shape change of
Even if the correlation between the nozzle gap and the electrical characteristic value of the gap sensor changes, this change can be automatically detected and a calibration command can be issued from the control device. Alternatively, the calibration can be reliably performed by notifying the operator of the execution of the calibration.
Therefore, the nozzle gap can always be accurately maintained, and stable and precise machining of the work can be reliably performed.

According to the third aspect of the present invention, the control device issues a calibration command when the electrical characteristic value from the sensor controller and the gap from the processing head movement amount detecting device exceed the threshold value. Calibration can be performed, and stable processing and precision processing of the work can be reliably performed.

[Brief description of the drawings]

FIG. 1, showing an embodiment of the present invention, is a schematic explanatory diagram of a calibration device.

FIG. 2 shows an embodiment of the present invention, and is a correlation diagram between a voltage and a nozzle gap showing a normal state and an abnormal state of a calibration adjustment value.

FIG. 3 is a front view showing the entire laser processing machine used in the embodiment of the present invention.

FIG. 4 is a schematic explanatory view of a conventional calibration device.

FIG. 5 is a correlation diagram between a voltage indicating a normal calibration adjustment value and a nozzle gap in the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser processing apparatus 9 Laser processing head 19 Calibration apparatus 21 Nozzle 23 Gap sensor 25 Sensor controller 27 Controller 31 Motor (Processing head raising / lowering apparatus) 33 Encoder (Processing head movement amount detecting apparatus) 41 Comparison and judgment apparatus

Claims (3)

[Claims] 1. A gap sensor detects a gap from a processing portion below a processing head to a work based on a correlation with an electrical characteristic, and inputs a detection signal to a control device via a sensor controller, and performs processing. A change in the amount of movement of the processing head, which moves up and down by the head elevating device, in the height direction is detected by the processing head movement amount detection device and input to the control device. The input electrical characteristic value from the sensor controller and the processing head movement The correlation between the gap detected from the change in the movement amount from the amount detection device and the calibration adjustment value based on the normal correlation between the gap and the electrical characteristics input in advance to the control device is abnormal. A gap cell in a machining head, characterized in that a calibration command is issued from a control device at a certain time. Calibration method of support. 2. A gap sensor for detecting a gap from a processing portion below a processing head to a workpiece based on a correlation with an electrical characteristic; a sensor controller for inputting a detection signal from the gap sensor to a control device; A processing head elevating device that moves the processing head up and down; a processing head movement amount detection device that detects a change in a movement amount of the processing head in a height direction; an electrical characteristic value from the sensor controller and the processing head movement amount detection The correlation between the gap detected from the change in the amount of movement from the device and the calibration adjustment value based on the normal correlation between the gap and the electrical characteristics input in advance is used to calibrate when there is an abnormal difference. And a control device for generating a command of the gap. Deployment apparatus. 3. The control device sets a threshold value as an abnormal value with respect to a calibration adjustment value in advance, and detects a threshold value from an electric characteristic value from the sensor controller and a change in the movement amount from the processing head movement amount detection device. 3. The apparatus for calibrating a gap sensor in a processing head according to claim 2, wherein a calibration command is issued when the gap exceeds the threshold value.