JPH0225596Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a laser cutting device for cutting a plate-shaped workpiece using a laser beam.

[Technical background of the invention and its problems]

For example, to cut a hole of a predetermined size in a plate-shaped workpiece using a laser beam, first cut a small hole in the workpiece using a laser beam, and then use this small hole as the starting point. The laser beam is scanned along the cutting line. In other words, if the laser beam is scanned without first machining a small hole, it will be difficult to cut the entire length of the workpiece in the thickness direction, and the laser beam will be scanned while the workpiece is being grooved.

By the way, when drilling a small hole in a workpiece using a laser beam, if the diameter of the small hole is larger than the cutting width, a step may be formed on the inner peripheral surface of the hole formed in the workpiece. This will result in poor cutting. However, when processing a small hole, simply by irradiating the workpiece with a laser beam of a predetermined output for a certain period of time, the diameter of the small hole is not constant depending on the thickness of the workpiece. Therefore, conventionally, the machining of the small holes has relied on the skill of the operator, which is not only inefficient but also leads to poor cutting. Another drawback was that it was not possible to continuously automate the machining of the small hole and the cutting process along the cutting line.

[Purpose of invention]

This invention enables the small hole that serves as the starting point for cutting to be machined to a predetermined diameter even if the thickness of the workpiece differs, and the machining of this small hole and the cutting process can be performed continuously and automatically. An object of the present invention is to provide a laser cutting device as described above.

[Summary of the idea]

When the laser beam for cutting the workpiece is output from the laser oscillator, the signal is input to the delay circuit, and the delay circuit changes the thickness of the workpiece from the time the laser beam is output. The XY table that drives the workpiece in the XY direction is operated with a delay of a predetermined time accordingly, and the workpiece is successively machined with a small hole and cut with this small hole as the starting point. It was made possible to do so.

[Embodiment of the invention] An embodiment of the invention will be described below with reference to FIGS. 1 to 3. In the figure, reference numeral 1 denotes an X table driven in the X direction by an X drive source 2. A Y table 4 driven in the Y direction by a Y drive source 3 is provided on the X table 1 . A plate-shaped workpiece 6 is placed on this Y table 4 by a jig 5.
is supported and fixed with a space formed between it and the upper surface of the Y table 4. A lens 8 held by a holder 7 is disposed above the workpiece 6. A laser beam L outputted from a laser oscillator 9 and whose direction is changed by a reflecting mirror 10 is incident on this lens 8 . Therefore, the laser beam L is focused by the lens 8 and irradiates the workpiece 6.

A supply pipe 12 equipped with an electric on-off valve 11 is connected to the peripheral wall of the holder 7 . This supply pipe 12 is connected to a gas supply source 13 in which a gas useful for cutting the workpiece 6, for example oxygen, is stored. Therefore, when the on-off valve 11 opens, gas from the gas supply source 13 flows from the holder 7 to the workpiece 6.
It is starting to be ejected towards.

The laser oscillator 9 is connected to a first control section 14 that controls the laser oscillator 9 to start and stop. Further, the first control section 14 is connected to the on-off valve 11 and a delay circuit section 16 having a delay time setting section 15 . The setting section 15 may be, for example, a circuit that obtains a predetermined delay time by switching a plurality of resistors that determine the time constant of a mono-multivibrator circuit.
When the first control section 14 operates the laser oscillator 9 to output the laser beam L, the signal is input to the on-off valve 11 and the delay circuit 16. When a signal indicating the output of the laser beam L is input to the on-off valve 11, the on-off valve 11 opens. Further, when the signal of the output laser beam L is input to the delay circuit 16, the setting section 15
The second control unit 17 is delayed by the time set in
A signal is output. The X drive source 2 and the Y drive source 3 are connected to the second control section 17, and when a signal is input from the delay circuit 16 to the second control section 17, the X and Y drive sources 2 and 3 are driven and controlled. That is, a cutting pattern is programmed in advance in the second control section 17, and the X and Y drive sources 2 and 3 are driven based on this program. Therefore, the laser beam L relatively scans the cutting line S of the workpiece 6 shown in FIG. 3.

Next, a case will be described in which a rectangular hole is machined in the workpiece 6 using the laser cutting device.
First, a plate-shaped workpiece 6 is placed on the jig 5 of the Y table 4.
is held and fixed, the delay time of the delay circuit 16 is set by the setting section 15 according to the thickness of the workpiece 6.
Set by. Next, the first control unit 14 is operated to operate the laser oscillator 9, and the laser beam L
output. Then, this laser beam L is reflected by the reflecting mirror 10, then focused by the lens 8, and irradiates the workpiece 6 at point A shown in FIG. 3. Also, at this time, the on-off valve 11 opens and gas from the gas supply source 13 is ejected onto the workpiece 6. Irradiation of point A of the workpiece 6 with the laser beam L continues until the X, Y tables 1 and 4 are driven, that is, for the time set in the setting section 15. Therefore, a small hole 20 is formed at point A of the workpiece 6, as shown in FIG. 2, passing through the workpiece 6 in its thickness direction.

The minimum time required to drill the small hole 20 in the workpiece 6 was determined through experiments as follows. In other words, if the workpiece 6 is a steel plate and the laser oscillator 9 is a YAG laser with an output of 150W, a pulse width of 20m _s , and a pulse repetition rate of 80PPS, if the workpiece 6 has a thickness of 2mm, the irradiation time is 1sec and 3mm. It was confirmed that the small hole 20 was drilled in 2 seconds when the diameter was 4 mm, and 3 seconds when the diameter was 4 mm.

Therefore, the setting section 1 of the delay circuit 16 calculates the time determined by the above experiment according to the thickness of the workpiece 6.
If it is set to 5, a small hole 20 with the smallest diameter can be formed in this workpiece 6. In other words, the diameter of the small hole 20 is not made larger than necessary, and the small hole 20 can be processed to pass through the hole 20 reliably.

In this way, when the small hole 20 is bored in the workpiece 6 and the time set in the setting section 15 has elapsed, a signal is output from the delay circuit 16 to the second control section 17, and the X, Y drive source 2 and 3 drive the X and Y tables 1 and 4. Therefore, the workpiece 6 is cut starting from the small hole 20. In other words, the laser beam L is transmitted along the cutting line S of the workpiece 6.
is irradiated in the order from point A through point B, point C, and point D to point A, so the workpiece 6 is irradiated with the above cutting line S.
A rectangular hole 21 along the line is bored. A small hole 20 is drilled in the workpiece 6 and serves as a starting point for cutting.
has a sufficiently small diameter and is almost the same as the cutting width along the cutting line S, so that a step due to the small hole 20 does not occur on the inner peripheral surface of the hole 21 formed in the workpiece 6.

In addition, in this example, when cutting each straight portion of the cutting line S, that is, AB, BC, CD, and DA, if the cutting length becomes several times the cutting width,
The scanning speed of the laser beam L may be increased.

FIG. 4 shows another embodiment of the invention. In this embodiment, one end of the workpiece is held by a chuck 25 provided on the Y table 4, and the workpiece 6 is held horizontally at a position off the top surface of the Y table 4. Further, the workpiece 6 is supported horizontally by rotatable rollers 26 so as not to be deflected. A holder 29 holding a lens 28 is provided on the lower surface side of the workpiece 6. The lens 28 focuses the laser beam L emitted from the lower surface side of the workpiece 6 and the radiation light from the cutting debris and guides it to the photoelectric converter 30 . This photoelectric converter 30 is connected to the delay circuit 16 via an amplifier circuit 31. Then, when the photoelectric converter 30 detects the emitted light and the detection signal is input to the delay circuit 16,
The delay operation of this circuit is canceled at that point, and the delay circuit 16 is configured to immediately output a signal to the second control section 17 before the preset delay time elapses, and with that signal, the table 1 , 4 are started to be driven by the X and Y drive sources 2 and 3 according to the programmed machining pattern.

Further, a supply pipe 33 provided with an on-off valve 32 is connected to the holder 29, and this supply pipe 32 is connected to a gas supply source 34. Further, the on-off valve 32 is connected to the first control section 14, and is opened in response to a signal when the laser oscillator 9 is operated by the first control section 14. Therefore, by supplying gas from the gas supply source 34 to the holder 29, the lens 28 is protected from cutting debris and the like.

According to such a configuration, the X, Y tables 1 and 4 remain stationary without being driven until the photoelectric converter 30 detects radiation emitted from the lower surface side of the workpiece 6. That is, when the workpiece 6 is irradiated with the laser beam L and the small hole 20 penetrates the workpiece 6, the emitted light can be detected on the lower surface side. Therefore, since the X, Y tables 1 and 4 are driven at the same time as the small hole 20 is bored in the workpiece 6, it is prevented from making the small hole 20 larger than necessary. That is, the X, Y tables 1 and 4 can be driven with a predetermined time delay depending on the thickness of the workpiece 6.

[Effect of idea]

As explained above, the present invention uses an XY table to drive the workpiece in the XY direction after a laser beam is output from the laser oscillator, with a predetermined time delay depending on the thickness of the workpiece. I got it working. Therefore, the small hole that serves as the starting point for cutting can be drilled in the workpiece to be sufficiently small even if the thickness of the workpiece is different, resulting in cutting defects such as dents in the cut surface due to the pilot hole. Never. In addition, machining efficiency can be improved because machining of a pilot hole according to the thickness of the plate and cutting with the pilot hole as a starting point can be performed continuously and automatically.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram showing one embodiment of the present invention, Fig. 2 is a cross-sectional view of a workpiece with a small hole drilled in it, and Fig. 3 is a similar sectional view of a workpiece with a laser beam applied to it. FIG. 4, which is an explanatory diagram for scanning, is a configuration diagram showing another embodiment of the present invention.

Claims (1)

[Scope of utility model registration request] A laser oscillator, a first control unit that controls irradiation of a plate-shaped workpiece with a laser beam output from the laser oscillator, and the workpiece to be cut by the laser beam are attached. An XY table, a second control unit that drives and controls the XY table in the XY direction, and a signal that causes the first control unit to operate a laser oscillator are input, and when this signal is input, the workpiece is and a delay circuit section that operates the second control section with a predetermined time delay depending on the plate thickness.