JP2597597B2 - Sensor output sampling method in laser beam machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a sensor output sampling method in a laser beam machine, and more particularly to a method in which a gap sensor integrated with a nozzle is provided. The present invention relates to an apparatus that can always perform appropriate gap amount constant control regardless of the operation.

(Prior art and its problems) Conventionally, in laser processing, the distance between the laser nozzle and the work, that is, the focus of the laser beam is always kept at a constant height with respect to the work in order to obtain the optimum processing state. A so-called gap control is performed in which the gap amount is always kept constant.

As a gap sensor for this purpose, there is a gap sensor provided with a contact type or non-contact type distance sensor at a position near the side of the laser nozzle. However, since the gap is detected at a position slightly deviated from the processing position, an appropriate gap amount cannot be measured at the processing position, and as a result, a good processing state cannot be obtained.

For this reason, an electromagnetic gap sensor such as a capacitance type,
Generally, a nozzle integrated with a nozzle or welded to the tip of the nozzle to detect a gap amount at a processing position in a non-contact manner is used.

However, when spatter S or high reflection heat which jumps violently from the work surface due to the laser irradiation is applied, the nozzle tip, that is, the sensor portion is melted by heat or abrasion is thermally deformed, and the deterioration of the sensor function cannot be avoided.

As a result, the sensor output characteristic with respect to the gap amount is different from the actual sensor output characteristic (for example, line A in FIG. 5), and is different from the actual gap amount in, for example, a much lower curve output characteristic (for example, line C in FIG. 5). ).

In such a case, proper gap control cannot be performed, and the processing state deteriorates. Therefore, it is necessary to replace the nozzle with a nozzle having proper initial sensor output characteristics. However, when the frequency of nozzle replacement increases, the work of replacing the nozzle becomes complicated, and processing must be stopped each time, which causes a reduction in work efficiency,
There were also economic problems.

In addition, for example, in a capacitance type gap sensor or the like, the characteristic curve of the sensor output voltage with respect to the change in the gap amount is not linearly proportional but curved, and therefore the gap amount cannot be easily calculated from the sensor output voltage. . For this reason, the measured gap amount cannot be displayed, and if the gap amount is not displayed, the worker cannot perform a reliable operation.

For this reason, in order to maintain an appropriate gap controller with the same nozzle for a long time, the sensor output characteristics of the nozzle are measured, sampled, and stored as appropriate.
An object of the present invention is to perform an appropriate gap control based on the stored sampling data, and at the same time, it is possible to display a gap amount which has been difficult in the related art, and to solve the above-mentioned problem.

(Means for Solving the Problems) In view of the above, the present invention provides a non-contact type gap sensor integrated with a nozzle, in which a means for sampling and storing the sensor output of the nozzle with respect to the actual gap amount is provided. By simply pressing the sampling command switch, the nozzle is automatically raised from the reference position by a specified amount, the sensor output at each position is measured, and the sensor output data for each gap amount is sampled and stored, thereby achieving this sampling. This is intended to perform a correct gap amount constant control with an appropriate gap amount based on data.

Further, the frequency of nozzle conversion due to a change in the sensor output characteristic of the nozzle is suppressed as much as possible, thereby eliminating the trouble of replacing the nozzle and improving the economical efficiency.

Further, the gap amount corresponding to the sensor output is easily read out based on the stored sampling data, thereby making it easy to display the gap amount and providing a gap amount display. It is designed to enable safe work.

That is, the present invention includes a gap sensor at the tip of the nozzle that detects the gap between the nozzle tip and the work in a non-contact manner, and performs a constant gap amount control based on the gap amount detected by the gap sensor. In a laser processing machine that performs processing, the laser processing machine moves a nozzle by a specified amount in a direction of an optical axis from a predetermined sampling reference position in a gap amount constant control OFF state based on a sampling command. Sampling means for sampling the sensor output from the nozzle corresponding to the gap amount and storing it in the sampling data storage circuit, and based on the nozzle check command, the nozzle is positioned at a predetermined check reference position in the gap amount constant control OFF state, and at that position, Measure the sensor output of the gap sensor of Nozzle checking means for determining that the output is within a reference output range set based on the stored sampling data, and determining that the output is out of the reference output range as NG; At the time, the gap amount constant control is performed based on the stored sampling data, and when the determination result of the nozzle check means is NG, the sampling means is operated to newly perform sampling, and the sampling data in the sampling data storage circuit is It is rewritten and stored.

(Operation) When the sampling command is issued by the sampling command means when the nozzle is first mounted, or when a processing defect is noticed, or at an arbitrary time, as shown in the sampling control flow of FIG. By the sampling driving means, when the gap amount constant control is OFF, the nozzle moves in the optical axis direction from a predetermined sampling reference position corresponding to, for example, the reference block (for example, from a position where the gap amount between the nozzle tip and the reference block is 0). , Is fed upward by a specified amount, for example, 0.1 mm. That is, these height positions are positions where the gap amount is actually changed to 0.1 mm, 0.2 mm, 0.3 mm,....

Each time the gap is moved, the sensor output from the nozzle is sampled and written to the sampling data storage circuit. If this sampling data is graphed, a characteristic curve such as the line A in FIG. 5 is obtained.

Then, at the time of the gap control of the gap amount constant control ON, as shown in the gap control control flow of FIG. 2, the corresponding gap amount stored in the sampling data storage circuit is read based on the sensor output of the nozzle sensor, This gap amount is compared with a preset gap amount set as a control reference value, and the deviation amount is used as a gap control signal,
The nozzle is sent to the drive motor circuit in the optical axis direction, and the nozzle is controlled in the optical axis direction so that the gap amount between the nozzle tip and the work coincides with the set gap amount.

If the sensor at the tip of the nozzle is deteriorated due to long use of the nozzle and the output characteristics of the sensor are changed, proper control of the gap cannot be performed. Therefore, the nozzle check is performed in advance by the nozzle check unit. That is, the nozzle is positioned at a predetermined check reference position, the sensor output at that position is measured, and if the value is within the reference output range, the sampling data as is is OK.
When it is out of the reference output range, a new sampling command is issued by the sampling command means, thereby automatically sampling the sensor output for each actual gap amount as described above. The sensor output data is newly rewritten.

In this way, even if the sensor output characteristics change, by sampling the sensor output of the nozzle at that time, the sensor output from the nozzle becomes the gap corresponding to the actual gap amount by the rewritten sampling data. With the amount, it is possible to continue proper gap control,
The need to replace the nozzle every time the nozzle deteriorates is eliminated.

(Embodiment) Next, a specific embodiment of the present invention will be described with reference to FIG. 4 and FIG.

The present embodiment relates to a laser processing machine used for, for example, flat plate processing, in which a laser processing head is moved in a Y-axis direction and a Z-axis direction with respect to a workpiece fed and moved in an X-axis direction.

The nozzle 1 is mounted on the laser processing head (not shown), and the optical axis is aligned with the Z axis. And nozzle 1 itself forms a capacitance sensor as the gap sensor, by detecting the electrostatic capacitance C _L between the nozzle tip and the workpiece W, for measuring the amount of gap therebetween in a non-contact It has become.

The sensor output from the nozzle 1 is converted into a DC voltage by the sensor circuit 2 and sent to the data processing circuit 3. The data processing circuit 3 includes a sampling data storage circuit 4,
A gap amount display circuit 5, a data comparison circuit 6, a Z-axis drive pulse generation circuit 7, and an output check circuit 8 are provided.

In the sampling data storage circuit 4, for example, 0.1 m
m, 0.2 mm, 0.3 m,..., and gap amount data for each 0.1 mm are registered in advance, and the sensor output voltage from the sensor circuit 2 is stored in a sensor output storage unit (not shown) corresponding to each gap amount. Is stored in correspondence with each gap amount data, and is rewritten successively with new sampling data at each sampling.

After the completion of the sampling, the gap amount data output from the sampling data storage circuit 4 based on the sensor output from the nozzle is sent to the data comparison circuit 6 and set in advance by the gap amount setting means 9 provided in the operation unit. This is compared with the set gap amount. The deviation between the two is sent to the Z-axis drive pulse generation circuit 7 as a gap control signal, and is sent to the Z-axis motor drive control circuit 12 via the number of interrupts 11 in the NC device 10 to perform Z-axis control. The nozzle 1 is controlled to move in the optical axis direction.

Further, the gap amount data output from the sampling data storage circuit 4 is numerically displayed on the gap amount display 13 via the gap amount display circuit 5 as it is.

The NC device 10 includes a normal processing program 14 for processing and feeding the nozzle 1 and a slide table (not shown) in the X, Y, and Z axis directions, and a program 15 for nozzle check.
Are selectively executed by a machining command 16 and a nozzle check command 17, respectively.

The Z-axis feed control signal from the machining program 14 is sent to the Z-axis motor drive control circuit 12 via the number of interrupts 11 described above,
The drive control of the Z-axis motor 18 controls the feed of the nozzle 1 in the optical axis direction.

Nozzle check program 15 controls gap amount constant
In the OFF state, as shown in the nozzle check control flow of FIG. 3, first, the nozzle 1 is automatically positioned at a check reference position corresponding to, for example, a reference block. The check reference position is set, for example, at a position where the gap amount between the nozzle tip and the reference block is 4.0 mm in the Z-axis direction. The sensor output from nozzle 1 at this position is
The output is sent to the output check circuit 8, and it is determined whether the output is within a reference output range set in advance by reference output setting means 19 provided in the operation unit.

As shown by the hatched area in FIG. 5, the reference output is set to a range of, for example, 6.2 V to 7.4 V with a check reference gap amount of 4.0 mm, and if the sensor output at the time of the check falls within this range, for example, The nozzle OK / NG display means 20 displays "OK" at points a and b in FIG. 5, and "NG" at point c in FIG.

In the case of "OK", the gap control can be continued with the sampling data as it is. In the case of "NG", the operator is warned with a warning lamp or an alarm, etc., and the nozzle should be replaced or the sampling data should be replaced. To rewrite.

Sampling data rewriting
By operating 21, a driving pulse for raising the Z-axis by 0.1 mm is generated from a Z-axis driving pulse generating circuit 7 serving as a sampling driving means, and the gap between the nozzle tip and the reference block is reduced from 0 to 0.1 mm. The nozzle 1 detects the capacitance at each position, the sensor output is sent to the sampling data storage circuit 4 via the sensor circuit 2, and the sampling of the sensor output voltage corresponding to each gap amount data is performed. Data is rewritten from old data to new data.

In this way, the current sensor output characteristics of the nozzle 1 are sampled, and during processing, gap amount data corresponding to the actual gap amount is obtained from the sampled data based on the sensor output, and sent to the data comparison circuit 6. The gap control is performed so that the gap amount between the nozzle tip and the work W always coincides with the set gap amount and becomes constant.

Note that it is also possible to easily incorporate a command program in the NC device 10 that automatically issues the nozzle check command 17 after the machining command 16 has been executed several times. Since the nozzle check is always performed, it is necessary to prevent the operator from overlooking to perform the nozzle check even if the sensor output characteristics have deteriorated, thus causing unexpected machining failures. Can be.

Furthermore, it is also possible to easily incorporate a sampling program executed by a sampling command into the NC device 10 and connect it to the interrupt circuit 11 similarly to the nozzle check program 15. The nozzle 1 is automatically sent to the sampling reference position by the NC device 10 and moved, and the Z-axis is immediately sent to the gap amount by a specified amount to drive and execute sampling, thereby improving workability. Becomes In this case, it is also possible to take in the NG output signal from the nozzle check and automatically execute the sampling program when NG is detected.

Further, the gap sensor is not limited to the capacitance type sensor, and may use another non-contact sensor such as a magnetic sensor.

In addition, the laser processing head has two additional
In a 5-axis laser beam machine that can control the direction of the optical axis at the irradiation end by providing a rotating main shaft, a gap control motor separate from the Z-axis motor is provided, and only the nozzle part can be moved in the optical axis direction. And a Z-axis drive pulse generation circuit 7
By sending the data to the drive control unit of the control motor instead of sending the data to the control motor, the feed control can be easily performed by adding the gap control at the tip of the nozzle in addition to the processing feed by the processing program. In the sampling driving of the nozzle, the control motor may be driven and controlled to move the nozzle by a predetermined amount in the optical axis direction.

In addition, the nozzle structure may be one in which the nozzle itself is configured as a gap sensor, one in which an electrode as a gap sensor is welded to the tip of the nozzle, or the first for gap detection.
The electrode and the second electrode provided to cover the side surface of the first electrode to eliminate the influence of the sensor output from the nozzle side by the three-dimensional work may be provided, and any other non-contact type sensor structure may be used. The present invention can be applied.

(Effects of the Invention) As described above, according to the present invention, the sensor function of the nozzle is deteriorated due to, for example, long use of the nozzle or the influence of spatter or high reflection heat, and the sensor output characteristic changes. Even if it occurs, the nozzle can be moved by a simple operation to change the gap amount by a specified amount, and each sensor output can be sampled and stored in the sampling data storage circuit. Since it is determined whether or not a new sampling is necessary, the sampling data can be rewritten or omitted depending on the degree of change in the sensor output characteristic. It is possible to have sampling data, and based on the gap amount data corresponding to the actual gap amount, a proper gap amount constant system I can do it. For this reason, the nozzle can be used effectively for a long time, the frequency of nozzle replacement is reduced, and workability and economy are improved. In the same nozzle, accurate constant gap amount control can be maintained without lowering the gap amount detection accuracy, and a good machining state can always be obtained.

Further, the gap amount corresponding to the sensor output is easily read based on the stored sampling data,
This facilitates the display of the gap amount, so that it is possible to provide a gap amount indicator, so that the worker can perform a safe operation.

[Brief description of the drawings]

FIG. 1 is a sampling control flow chart in the laser beam machine according to the present invention, FIG. 2 is a gap control control flow chart of the above, FIG. 3 is a nozzle check control flow chart of the same, and FIG. 4 is a specific control circuit of the present invention. FIG. 5 is a diagram showing a change in sensor output characteristics and a reference output range. 1 ... Nozzle integrated with gap sensor, 2 ... Sensor circuit, 4 ... Sampling data storage circuit, 5 ... Output check circuit constituting nozzle check means, 7 ...
A Z-axis drive pulse generation circuit as sampling driving means constituting sampling means; 15 a nozzle check program constituting nozzle checking means; 17 nozzle check command means constituting nozzle checking means;
... Z-axis motor as control drive motor, 19 ...
... reference output setting means constituting nozzle check means, 21
... Sampling command means constituting the sampling means, W... Work.

Claims (1)

(57) [Claims] A gap sensor for detecting a gap amount between a nozzle tip and a work in a non-contact manner at a tip end of a nozzle, and performs constant gap amount control based on the gap amount detected by the gap sensor. In a laser processing machine that performs processing, the laser processing machine moves a nozzle by a specified amount in a direction of an optical axis from a predetermined sampling reference position in a gap amount constant control OFF state based on a sampling command. Sampling means for sampling the sensor output from the nozzle corresponding to the gap amount and storing it in the sampling data storage circuit, and the gap amount constant control based on the nozzle check command
In the OFF state, the nozzle is positioned at a predetermined check reference position, the sensor output of the gap sensor at that position is measured, and if the value is within the reference output range set based on the stored sampling data, OK, and a nozzle check means for judging NG if it is out of the reference output range.
When OK, the gap amount constant control is performed based on the stored sampling data, and when the determination result of the nozzle check means is NG, the sampling means is operated to newly perform sampling and the sampling data in the sampling data storage circuit. A method for sampling a sensor output in a laser processing machine, wherein