JPH02108490A - Laser beam machining method - Google Patents

Abstract

PURPOSE:To carry out high-precision layer beam machining at low cost by spouting pressurized assistant gas composed of oxygen and air having a prescribed mixing ratio from a working head to a working part together with laser beam with which a work is irradiated. CONSTITUTION:The work 7 is irradiated by the laser beam 2 from a laser beam oscillator 1 which is converged by a mirror 3, a lens 5, etc., through the nozzle 6 of a working head 5. Simultaneously in a mixing circuit 16 composed of mass flow controllers 17, 18 and a mixer 21, a mixing ratio is set to air obtained by a compressor 9 and oxygen from a bomb 14 according to a working condition respectively, they are mixed and injected from a nozzle 6 as the assistant gas at high pressure. This mixing ratio is set manually through flow rate setters 19, 20 or through the control of an NC device. The pressure of this assistant gas is desired to be >=10kg/cm<2>. By this method, working such as cutting is carried out efficiently, the adhesive quantity of dross is reduced and generation of the self-burning, etc., at an edge part can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a laser processing method for processing a workpiece using a laser beam.

[Conventional technology]

Generally, when cutting a workpiece with a laser beam, an assist gas is used to blow away the dross generated during cutting, and the flow rate of the assist gas is controlled depending on the processing situation and the form of laser output. This method is known, for example, in Japanese Patent Application Laid-Open No. 289991/1983.

In addition, an inert gas such as N2 or Ar is used as the assist gas to prevent oxidation of the cut surface, but in order to reduce running costs, air is used as the assist gas, and the oxygen in the air is A laser processing method that uses an absorbent or the like to absorb the heat has also been proposed. For example, JP-A-81-150
No. 794 etc.

[Problem to be solved by the invention]

However, when air is used as the assist gas, high-speed cutting causes dross to form on the back of the product, so processing must be performed at relatively low speeds, resulting in low productivity.

There is also a processing method that uses oxygen as an assist gas,
When oxygen is used, processing conditions must be set each time depending on the cutting speed, resulting in problems such as troublesome condition setting.

This invention has been made to improve the above-mentioned problems, and aims to provide a laser processing method that has low running costs and does not cause self-burning or chipping of minute parts or edge parts.

[Means and effects for solving the problems] In order to achieve the above object, the present invention provides a method in which assist gas is irradiated from a machining head toward a workpiece with a mixing ratio of oxygen and air set according to machining conditions. The object of the present invention is to provide a laser processing method in which a workpiece is cut by ejecting a laser beam at high pressure to a processing section, thereby producing a product free of dross and the like.

〔Example〕

An embodiment of the method of this invention will be described in detail with reference to the drawings.

In FIG. 1, 1 is a laser oscillator, and a laser beam 2 emitted from this laser oscillator 1 is guided to a processing head 4 via a plurality of mirrors (only one is shown in the figure) 3, and is guided inside the processing head 4. The light is condensed by a lens 5 provided at the , and irradiated from a nozzle 6 toward a workpiece 7 to be used for cutting the workpiece 7 .

Further, since the lens 5 installed in the processing head 4 uses high-pressure air as an assist gas, a lens with a pressure resistance of, for example, 15 kg/c- is used, and a compressor 9 that supplies air as the assist gas is used. Considering the pressure loss of piping and pneumatic equipment, we use one with a discharge pressure of 12 kg/c- or more.

This increases the jetting pressure of the processing head 4 to 11kg/c.
- In addition to the above, the compressor 9 is of an automatic unloading type in order to obtain a large amount of air flow.

On the other hand, the air discharged from the compressor 9 is supplied to a dry unit 10, an air tank 11, a solenoid valve 12, and a pressure adjustment circuit 1.
Oxygen from a gas cylinder 14, which is an oxygen supply source, can be individually supplied to the processing head 4 via a solenoid valve 15 and a pressure adjustment circuit 13. The mixture can be supplied to the processing head 4 in a mixed state at the specified mixing ratio.

The mixing circuit 16 is a mass flow controller 17.18 that introduces air and oxygen from the upstream side of the solenoid valve 12.15.
have.

These mass flow controllers 17.18 discharge the flow rate set in advance by the flow rate setting device 19.20 to the mixer 21, and the mixer 21 discharges the air and oxygen discharged from each mass flow controller 17.18. The mixture is supplied to the processing head 4 via the pressure setting circuit 12.

Incidentally, the flow rate setting of the mass flow controllers 17.18 is not limited to manual setting using the flow rate setting devices 19.20, but may of course be performed by commands from an NC device (not shown).

Next, to explain the operation, when cutting mild steel (SS41) as the workpiece 7 to be machined, the mixing ratio of oxygen and air must be adjusted manually or by NC in advance depending on the thickness of the workpiece 7.
Then, while irradiating the workpiece 7 with the laser beam 2 from the cutting head 4, oxygen and air at a preset mixing ratio are simultaneously ejected as assist gas to the workpiece 7 to start cutting.

For cutting, piercing was first performed, and then the cutting proceeded, but the assist gas pressure was maintained at 11 kg/c- at the time of ejection to prevent dross from adhering.

As a result, the state of adhesion of dross could be significantly reduced as shown in FIG.

In addition, by setting the machining conditions as shown in Table 1 or Table 2 below according to the thickness of the workpiece 7, continuous oscillation (C
W) It is now possible to cut minute parts and sharp edge parts with a laser processing machine using the laser oscillator 1, and it is now possible to prevent self-panning and chipping of these parts without using a pulse generator. Ta.

For comparison, conventional processing conditions are shown in Tables 3 and 4, respectively.

(Leaving space below) Table-1 Table-2 Table-3 Table-4 [Effects of the invention] As detailed above, this invention uses high-pressure assist gas with a mixing ratio of oxygen and air set according to the processing conditions to the laser beam. The workpiece is machined while being irradiated and ejected toward the workpiece.By increasing the pressure of the assist gas, the amount of dross adhering to the workpiece can be significantly reduced, improving the quality of the product. It becomes like this.

In addition, continuous wave laser beams make it possible to process minute parts and sharp edges, and in the case of thin plates, continuous wave laser cutting is possible with only air as an assist gas, and even in the case of relatively thick plates, oxygen By mixing these, continuous wave laser cutting becomes possible, and running costs can be significantly reduced compared to when conventional inert gases are used.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a circuit diagram, and FIG. 2 is a diagram showing the relative ratio of assist gas and dross adhesion state. 2 is a laser beam, 4 is a processing head, 7 is a workpiece, 17.18 Mass flow controller, 19
．． 20 is a flow rate setting device.

Claims (3)

[Claims] (1) Assist gas with a mixing ratio of oxygen and air set according to the processing conditions is ejected at high pressure to the processing area together with the laser beam 2 that is irradiated from the processing head 4 toward the workpiece 7 to process the workpiece 7. A laser processing method characterized by: (2) The mixing ratio of oxygen and air used as assist gas is controlled by the mass flow controllers 17 and 18 that are manually set by the flow rate setting devices 19 and 20 or by the mass flow controllers 17 and 18 that are controlled by the NC device depending on the processing conditions. 2. The laser processing method according to claim 1, wherein: (3) The laser processing method according to claim 1, wherein the pressure of the assist gas is set to 10 kg/cm^2 or more.