JPH0134718B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in laser cutting devices.

An example of a conventional device of this type is shown in FIG.

In the figure, 1 is a laser oscillator, 2 is a laser beam generated by the laser oscillator 1, the direction of the laser beam 2 is changed by a reflector 3, and the beam is focused by a lens 4 to perform processing such as cutting or welding on a workpiece 5. I do. Further, the workpiece 5 can be processed in a straight line by moving the table 7 using the motor 6. 8
9 is an amplifier circuit for driving the motor 6, and 9 is a lamp circuit for suppressing the acceleration of the table 7.

Next, the operation of this conventional device will be explained. In the case of laser cutting, first, the table 7 starts moving in response to a movement start signal, and at the same time, the laser beam 2 is output.

The moving speed of the table 7 needs to be raised and lowered gradually as shown in FIG. 2b, depending on the weight and strength of the table 7, the magnitude of the torque of the motor 6, etc. The lamp circuit 9 generates this signal. On the other hand, as for the laser output, a laser beam having a constant intensity is output as shown in FIG. 2a.

Generally, in laser cutting, when the cutting speed is slow, the cut portion is heated and the width of the cut becomes wider. For this reason, in conventional laser cutting equipment, the heat input is relatively large during acceleration and deceleration such as starting and stopping, and as shown in Figure 3, the cutting width 10 is wide during laser cutting. It also had drawbacks such as partial melting.

This invention was made to eliminate the drawbacks of the conventional ones as described above, and when laser cutting,
The movement command speed is made proportional to the output (intensity) of the laser beam, and when the movement command speed is zero, the laser beam output is set to a predetermined value that is smaller than the intensity when the command speed is present and is not zero. It is an object of the present invention to provide a device that can improve laser cutting accuracy by providing a control device that controls the value.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 shows an embodiment of the present invention, and in the figure, the control signal for the intensity of the laser beam is obtained from the output signal of the lamp circuit 9, that is, the movement command signal. As shown in FIG. 5b, this signal is a signal that changes in a ramp-like manner when the movement starts and stops.

Next, the operation of this embodiment device will be described. First, the laser beam 2 is outputted at the same time as the table 7 starts moving in response to a movement start signal, similar to the conventional circuit. However, since the laser beam 2 is controlled to be proportional to the movement command speed, its output gradually increases as shown in FIG. 5a.

When performing laser cutting with such a configuration, assuming that the movement command speed and the actual movement speed are approximately equal, the laser beam is controlled in proportion to the movement speed, so the table movement speed becomes faster or slower depending on the acceleration/deceleration. The workpiece 5 is not heated even when the workpiece 5 is bent, and the laser cutting width can be kept constant.

That is, the cutting width 1 of the workpiece shown in FIG.
0 makes it possible to always cut to a constant width like the cutting width 10 shown in FIG.

Note that it is necessary to prevent the laser output from becoming zero when the moving speed is zero.

This is because it is generally known that in such laser processing, processing is performed using an average value of input energy. Of the input energy, the effective energy for machining is the value obtained by subtracting the energy that escapes due to heat conduction from the input energy, and the energy for machining is equivalent to the difference between the machining temperature and the temperature immediately before machining. You need something to do. Therefore, in the above-described machining, in a region where the machining speed is low, the energy that escapes due to heat conduction becomes relatively large, and the temperature immediately before the machining becomes low, so it is necessary to correct this. Therefore, when the machining speed, that is, the command speed is the lowest, zero, by setting the intensity of the laser beam to a small non-zero value and irradiating it, the above-mentioned correction will be performed and uniform machining will be performed. It will be.

Generally, when a user wants to control the laser output, he does not control the laser power supply only with the control voltage signal V ₁ , but he also uses the control voltage signal V ₁ as well as the power supply. If a fixed voltage signal V ₂ is generated, these two voltage signals V ₁ ,
The voltage for laser output control is determined by the sum signal _V3 of _V2 .

In this way, when the moving speed is zero and the moving speed signal is zero, only the fixed voltage signal V ₂ is present, so in this case the laser output is set to the predetermined minimum output, and this fixed voltage signal V ₂ is used. In addition, when a movement command signal is generated, the laser output increases in proportion to the magnitude of the signal, so that the output is finally obtained in the form shown in FIG. 5a.

Table 7 describes an example of one-dimensional movement, but even in two-dimensional, three-dimensional, or more-dimensional cases, the same effect can be achieved if the intensity of the laser beam is controlled by the synthesized velocity vector amount. Effects can be obtained.

Further, in the case of simultaneous movement in two or more dimensions, the same effect can be obtained even in the case of acceleration and deceleration at the corner portion of the workpiece to be laser cut.

As described above, according to the present invention, during laser cutting, the movement command speed and the intensity of the laser beam are made proportional, and when the movement command speed is zero, the laser beam output is adjusted to the intensity when the command speed is present. Since we have installed a control device that controls the value to a predetermined value that is smaller than that of , and is not zero, uniform processing can be performed, and the laser cutting width can be kept constant, which has the effect of greatly improving cutting accuracy, finish, etc. There is.

[Brief explanation of drawings]

Figure 1 is a block diagram of a conventional laser cutting device.
Fig. 2 is a diagram showing the relationship between laser output and moving speed of a conventional device, Fig. 3 is a plan view of an example cut by the conventional device, and Fig. 4 is a block diagram showing an embodiment of the laser cutting device according to the present invention. 5 is a diagram showing the relationship between the laser output and the moving speed of the device of the present invention, and FIG. 6 is a plan view of an example cut by the device of the present invention. 1 is a laser oscillator, 2 is a laser beam, 3 is a reflecting mirror, 4 is a lens, 5 is a workpiece, 6 is a motor, 7
is a table, 8 is an amplifier circuit, 9 is a lamp circuit, 1
0 is the cutting width. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1. In an apparatus that includes a laser oscillator that generates a laser beam and moves the workpiece relative to the laser beam to laser cut the workpiece, the relative movement between the laser beam and the workpiece. At the same time, the intensity of the laser beam during laser cutting is proportional to the movement command speed, and when the command speed is zero, the intensity of the laser light is smaller than the intensity when there is a command speed, and it is not zero. What is claimed is: 1. A laser cutting device characterized by comprising a control device for controlling to a predetermined value.