JPH05154674A - Laser beam machine - Google Patents

Abstract

PURPOSE:To prevent working abnormality from being generated and to perform laser beam machining high in reliability by infecting water to a working point of a material to be worked and cooling the material to be worked when the temperature of the material to be worked during laser beam machining exceeds a set value. CONSTITUTION:When a processor 21 of a numerical controller 1 judges that the material 8 to be worked is being cut, temperatures at the neighborhood of the working point of the material 8 to be worked are detected by temperature sensors Sa-Sd and read through amplifiers Aa-Ad and an A/D converter 26. The average value of three detected temperatures other than the detected highest temperature is required and compared with the set value. When the detected average value exceeds the set value, a solenoid valve 12 is opened through an I/O unit 24, water is injected from a cooling water injection nozzle 13 to the neighborhood of the working point to cool the material to be worked.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing apparatus, and more particularly to a laser processing apparatus for cutting a workpiece with a laser.

[0002]

2. Description of the Related Art In recent years, the output of a laser processing machine has been increasing, and it has become possible to process a material having a plate thickness which was previously impossible by laser processing. Also, the application of laser processing is making progress in the fields of welding and heat treatment. Among the wide range of laser processing techniques, a physical problem of a work piece is often a problem. In order to perform stable laser processing, a certain quality is required for the work piece. However, such physical properties depend on temperature, and considering that laser processing is a kind of thermal processing, it is necessary to consider the temperature of the workpiece during processing.

In particular, when a thick steel sheet is cut by laser processing, if the steel sheet is at a normal temperature, it can be cut well, but heat is accumulated as the processing proceeds,
Eventually, despite the same amount of heat input, burning (a state in which the cutting width spreads widely and a very rough cutting surface) occurs, resulting in a state of excessive heat input. Further, in the vicinity of the place where the wire is once cut, the piercing often fails because the temperature is high. As described above, if the temperature of the workpiece is already high, it often has a serious influence on the laser processing, which is a problem of the laser processing technology.
As a measure against the above-mentioned problems, the conventional method is only entrusted to the intuition and experience of the operator who operates the laser processing apparatus.

[0004]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems and to provide a laser processing apparatus capable of preventing a temperature rise of a workpiece and performing stable laser processing. ..

[0005]

According to the present invention, a machining head is provided with a temperature sensor for measuring the temperature of a work piece near the machining point and a nozzle for injecting water for cooling the vicinity of the machining point. The above problem was solved by injecting water from the nozzle when the temperature detected by the sensor exceeds a set value. Preferably, when only one temperature sensor is provided, the temperature sensor is used to detect the temperature of the workpiece in the direction in which the processing is proceeding. Further, a plurality of temperature sensors are provided, and the control means causes the nozzle to inject water when the average value of the detected temperatures other than the maximum temperature detected by the temperature sensors exceeds the set value. ..

[0006]

When the laser processing is started on the workpiece, the temperature sensor measures the temperature of the workpiece near the processing point. The control means compares the temperature detected by this temperature sensor with the set temperature, and if the detected temperature is below the set value,
Laser processing will proceed as before. On the other hand, when the detected temperature exceeds the set value, water is jetted from the nozzle to the work piece to perform the work while cooling the work piece. When the work piece is cooled with water, the temperature of the work piece decreases, and the temperature detected by the temperature sensor also decreases. Then, when the detected temperature becomes equal to or lower than the set value, the water injection is stopped. Below, when the temperature detected by the temperature sensor exceeds the set value, water is sprayed from the nozzle to cool the work piece, so the temperature rise of the work piece is suppressed, and abnormal laser processing does not occur due to the temperature rise. Stable laser processing is performed with a small number. Generally, the temperature of the work piece immediately after working is very high and does not represent the temperature of the work piece to be worked, and this point should be avoided. Therefore, when only one temperature sensor is attached to the machining head,
By detecting the temperature of the work piece in the machining progress direction by the temperature sensor, the temperature of the work piece immediately before the processing (cutting) of the work piece is detected by the laser, and the temperature of the work point is detected. Try to detect the temperature of the work piece more accurately. Also, if multiple temperature sensors are attached to the processing head, the average value of the other detected temperatures among the temperatures detected by this temperature sensor, excluding the maximum detected temperature, is calculated and compared with the set value. To do it. That is,
Since the maximum detected temperature may represent the temperature of the work piece immediately after processing, the average of other detected temperatures excluding this maximum temperature is calculated and this average value is compared with the set value. Is.

[0007]

1 is a block diagram of a laser cutting apparatus according to an embodiment of the present invention. The processor 21 of the numerical controller (NC) 1 reads the machining program stored in the memory 23 based on the control program stored in the ROM 22 and controls the operation of the entire laser cutting device. The I / O unit 24 drives the laser oscillator 2 according to the control signal from the processor 21, and emits a pulsed laser beam 6 from the laser oscillator 2. This laser beam 6
It is reflected by the bending mirror 3 and sent to the laser processing machine 4. In addition, the processor 2 via the I / O unit 24
1 is a solenoid valve 1 for supplying water to a nozzle 13 for injecting cooling water
Control 2 The nozzle 13 for jetting the cooling water is attached to the head 5 and jets water near the processing point.

The laser processing machine 4 is provided with a table 7 on which a workpiece 8 is fixed and a processing head 5 for irradiating the workpiece 8 with a laser beam 6. The laser beam 6 introduced into the processing head 5 is focused by the nozzle 5a and is applied to the workpiece 8. The laser processing machine 4 is provided with servomotors 9 and 10 for controlling the movement of the table 7 in two directions orthogonal to the X axis and the Y axis, and a servomotor 11 for controlling the movement of the processing head 5 up and down. Has been.
These servomotors 9, 10 and 11 are connected to servo amplifiers 27, 28 and 29, respectively, and their rotation is controlled according to the axis control signal from the processor 21. Also,
The instruction to the laser processing machine 4 is given via the CRT / MDI 25. In addition to the nozzle 13 for jetting cooling water described above, a plurality of non-contact type temperature sensors for detecting the temperature of the workpiece near the laser processing point are attached to the processing head 5. In this embodiment, four temperature sensors Sa to Sd are attached. The outputs of these temperature sensors Sa to Sd are input to the A / D converter 26 for converting an analog signal into a digital signal via the amplifiers Aa to Ad, and the output of the A / D converter 26 is bus-connected to the processor 21. There is.

The configuration of the above laser cutting device is the same as that of the conventional NC laser device except that the nozzle 13 for injecting the cooling water, the temperature sensors Sa to Sd, etc. are provided, and details thereof will be omitted. 2 shows the nozzle 5a of the processing head 5.
In the partial view of the portion, the temperature sensors Sa to Sd detect the temperature of the workpiece 9 near the processing point in a non-contact manner, and
This shows that the cooling water is jetted from the nozzle 13 for jetting the cooling water to the vicinity of the processing point.

FIG. 3 is a flow chart of a process executed by the processor 21 of the numerical controller 1 for controlling the temperature of the workpiece 8 at predetermined intervals. The processor 21 performs the process shown in FIG. 3 every predetermined period, and first determines whether or not the cutting is in progress (step S1). The processor 21 sets a flag when a cutting processing start command is read from the processing program, and determines whether or not cutting is in progress depending on whether or not this flag is set.
Then, if it is not being disconnected, this processing is ended as it is. On the other hand, if the cutting is being performed, the temperature near the processing point of the workpiece 8 detected by the temperature sensors Sa to Sd and input via the amplifiers Aa to Ad and the A / D converter 26 is read (step S2), The maximum temperature of the detected temperatures is obtained (step S3). That is, the temperature detected by the temperature sensor Sa and the temperature detected by the temperature sensor Sb are compared, the larger one is stored in the register, and the stored detected temperature and the temperature detected by the temperature sensor Sc are compared and the larger one is compared. Store in register. Further, the temperature stored in this register is compared with the temperature detected by the temperature sensor Sd, and the larger one is stored in the register. As a result, the value stored in the register indicates the maximum temperature detected by the temperature sensors Sa to Sd. Generally, the temperature of the work piece immediately after being cut by the laser processing is extremely high, and does not represent the temperature of the work piece at the point to be processed. Therefore, this maximum temperature is discriminated from the data after machining, and the temperature of the workpiece is detected by the remaining detected temperature.

That is, the average value of the other three detected temperatures excluding the detected maximum temperature is calculated (step S4),
The average value and the set value are compared, and when the detected average value temperature is equal to or lower than the set value, the flag F (this flag is set to "1" when the detected average value exceeds the set value as described later) is set to " It is determined whether or not it is "1" (step S9), and if it is not "1", the process of the cycle is ended. Below each cycle,
When the detected average value is less than or equal to the set value, steps SS1 to S
5 and step S9 will be repeatedly executed.

On the other hand, if it is determined in step S5 that the detected average value (average temperature) exceeds the set value, it is determined whether the flag F is "1" (step S6). Since there is not, go to step S7, I / O unit 24
The electromagnetic valve 12 is opened via the and the water is jetted from the cooling water jet nozzle 13 to the vicinity of the processing point. Then, the flag F is set to "1" (step S8), and the process of the cycle is completed. From the next cycle, the processing of steps S1 to S6 is performed as long as the detected maximum temperature exceeds the set value, and since the flag F is "1", the processing of that cycle is ended. As a result, when the detected average value of the detected temperatures excluding the maximum detected temperature exceeds the set value, the water is continuously jetted from the cooling water jet nozzle 13 to the vicinity of the processing point.

Water is jetted in the vicinity of the processing point of the workpiece 8,
When the workpiece 8 is cooled and the temperature detected by the temperature sensors Sa to Sd decreases, and the detected average value becomes equal to or less than the set value, the process proceeds from step S5 to step S9, and the flag F is "1". In step S10, the solenoid valve 12 is closed to stop the water injection, and the flag F is set to "0" (step S11). After that, the water is not injected unless the average value of the detected temperatures excluding the maximum detected temperature exceeds the set value.

As described above, while the maximum temperature among the temperatures detected by the temperature sensors Sa to Sd exceeds the set value, water is jetted from the cooling water nozzle 13 to the vicinity of the processing point and the workpiece 8 is When cooled and the detected maximum temperature becomes equal to or lower than the set value, water injection is stopped.
The temperature does not greatly exceed the set value and is kept below a predetermined value. As a result, stable laser cutting can be performed.

Although four temperature sensors are installed in the above embodiment, more temperature sensors may be installed.
Alternatively, only one temperature sensor may be installed. When one temperature sensor is installed, it is preferable to introduce C-axis control (control of rotational position around the central axis of the machining head) for controlling the position of this temperature sensor,
It is advisable to detect the temperature of the work piece in the machining progress direction with this one temperature sensor, and to detect the temperature of the position of the work piece to be processed with the laser. Further, as a measure against the case where the temperature rises even if the workpiece is cooled with cooling water, a second set value larger than the set value to be compared with the detected average value in step S5 of FIG. 3 is set. Alternatively, it may be determined between steps S4 and S5 whether or not the detected temperature exceeds the second set value, and when it exceeds, the laser processing may be stopped.

[0016]

According to the present invention, when the temperature of the work piece exceeds the set value during laser processing, water is jetted to the working point of the work piece to cool the work piece. Does not greatly exceed the set value and is maintained at a predetermined value or less, so that it is possible to prevent the occurrence of processing abnormalities and obtain a highly reliable laser processing apparatus. Further, even when the laser processing apparatus of the present invention performs unmanned processing at night or the like, the temperature of the workpiece is prevented from rising abnormally, so that the processing may be interrupted due to the temperature rise. It is possible to perform unattended operation at night and perform efficient machining work.

[Brief description of drawings]

FIG. 1 is a block diagram of a laser cutting device according to an embodiment of the present invention.

FIG. 2 is a partial view of a nozzle portion of a processing head according to the embodiment.

FIG. 3 is a flowchart of a process performed by the processor of the numerical control device according to the first embodiment at predetermined intervals to control the temperature of the workpiece.

[Explanation of symbols]

 1 Numerical Control Device 2 Laser Oscillator 4 Laser Processing Machine 5 Processing Head 8 Workpiece 12 Electromagnetic Valve 13 Cooling Water Jet Nozzle Sa-Sd Temperature Sensor

Claims (2)

[Claims] 1. A laser processing apparatus for processing a workpiece by condensing a laser beam using a focusing device, wherein a temperature sensor for measuring the temperature of the workpiece near the processing point and a vicinity of the processing point are mounted on a processing head. Provided with a nozzle that sprays cooling water,
A laser processing apparatus comprising: a control unit that controls to inject water from the nozzle when the temperature detected by the temperature sensor exceeds a set value. 2. A plurality of the temperature sensors are provided, and the control means injects water from the nozzle when the average value of the detected temperatures excluding the maximum value of the temperatures detected by the temperature sensors exceeds a set value. Item 2. The laser processing apparatus according to item 1.