JPH04300084A - Laser beam machine - Google Patents

Abstract

PURPOSE:To execute cutting without necessity of the change of defocus quantity at the piercing time and the cutting time and to improve the working efficiency. CONSTITUTION:An auxiliary lens 8 of long focus distance is interposed in the light transmitting system 7 between the laser oscillator and the condensing lens 5 in the machining head 4, and also the piercing and the cutting is executed by setting the converging point 9 of the laser beam 2 with the condensing lens 5 being made so as to be lower from the front surface 6a of the material 6 to be machined, the piercing and the cutting is executed.

Description

[Detailed description of the invention]

[Purpose of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing machine suitable for cutting a workpiece.

0002

2. Description of the Related Art When cutting a workpiece using a laser beam machine, normally a small penetrating hole called piercing is first formed in order to create a starting point for cutting.

[0003] Since this hole is not necessary for forming the cut shape, any shape can be used for cutting as long as it passes through the hole. However, if the area around the hole in the workpiece is heated more than necessary by the laser beam irradiated during piercing, the cutting conditions will differ between the heated area and the unheated area.
It tends to be difficult to perform good cutting. For this reason, when performing piercing, conditions are applied in which pulsed laser light is used and the irradiation time is shortened to suppress heating of the workpiece.

[0004] After performing such drilling, the workpiece is cut into a desired shape by scanning a laser beam according to the cutting conditions of the workpiece, thereby producing a product.

[0005]

[Problems to be Solved by the Invention] Laser light emitted from a laser processing machine is focused by a condensing lens installed inside the processing head and irradiated onto the workpiece, so it has a high energy density. The area is narrow and limited to the vicinity of the focal point. Therefore, when piercing or cutting, the light condensing point is set near the surface of the workpiece, but the setting conditions vary depending on the thickness of the workpiece.

[0006] The position of the converging point of the laser beam relative to the surface of the workpiece is one of the laser processing conditions, and this value is generally referred to as the amount of defocus. This defocus amount is positive when the focal point is above the surface of the workpiece, and negative when it is below.

[0007] When the thickness of the workpiece increases, the optimal value for the amount of defocus during cutting is on the plus side, but on the other hand, the amount of defocus during piercing depends on the time required for piercing. To make it the shortest, it is necessary to set it on the negative side from zero. That is, if the defocus amount at the time of piercing is set to the optimal value (setting on the negative side from zero), the set value will be a value different from the optimal value (on the positive side) at the time of cutting.

[0008] Therefore, in order to perform both processes under optimal conditions, it is necessary to change the defocus amount, that is, the position of the focal point with respect to the surface of the workpiece, each time the piercing and cutting processes are switched. . However, in order to make such a change, the processing head becomes complicated and the operation becomes complicated, so piercing is generally performed with the defocus amount set at the time of cutting. In this case, there is a problem that the time required for the hole to penetrate during piercing becomes longer, and the overall time required for processing becomes longer, resulting in poor processing efficiency.

The present invention has been made in view of the above circumstances, and its object is to be able to perform cutting without changing the amount of defocus between piercing and cutting, thereby improving processing efficiency. The object of the present invention is to provide a laser processing machine that can be improved. [Structure of the invention]

0010

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention guides a laser beam emitted from a laser oscillator to a laser processing head via an optical transmission system. In a laser processing machine that cuts a workpiece by irradiating the workpiece through a condensing lens provided therein, an auxiliary lens with a long focal length is interposed in the light transmission system, and , the condensing point of the laser beam by the condensing lens is set to be below the surface of the workpiece.

[0011]

[Action] By interposing an auxiliary lens with a long focal length in the light transmission system, it was found that the optimal value of the amount of defocus during cutting can be changed to the negative side, whereas previously it was only on the positive side. . This makes it possible to set the optimal value of the defocus amount during cutting to the same negative value as the optimal value of the defocus amount during piercing. There is no need to change the focus amount, and piercing can be performed in a short time, which in turn allows efficient cutting.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. First, in FIG. 1, a laser beam 2 emitted from a laser oscillator 1 is directed to a processing head 4 after being directed by a beam bender 3 consisting of a reflecting mirror. A condensing lens 5 is disposed within the processing head 4, and the workpiece 6 is processed by irradiating the workpiece 6 with laser light 2 that is focused by the condenser lens 5. It looks like this.

In the optical transmission system 7 between the laser oscillator 1 and the condensing lens 5, an auxiliary lens 8 consisting of a convex lens with a long focal length is disposed between the laser oscillator 1 and the beam bender 3. It is set up. Further, at this time, the condensing point 9 of the laser beam 2 condensed by the condensing lens 5 is set below (inside) the surface 6a of the workpiece 6.

Here, an experiment was conducted to compare the laser cutting performance between the configuration of this embodiment in which the auxiliary lens 8 is interposed in the optical transmission system 7 as described above, and the conventional configuration in which the auxiliary lens is not interposed. The results are shown in Figure 2. In the experiment, a mild steel material with a plate thickness of 16 mm was used as the workpiece 6, and this was cut. Further, in this example, the auxiliary lens 8 used had a focal length of 10 inches.

In FIG. 2, the position of the focal point relative to the surface of the workpiece, that is, the amount of defocus, is taken as the vertical axis, and the white circle indicates the case where good cutting without dross is possible during cutting. Other cases in which good cutting cannot be obtained are indicated by black circles.

As is clear from FIG. 2, in the case of the conventional configuration, the region of defocus amount where good cutting is possible is concentrated on the plus side, and good cutting is not obtainable on the minus side. It's something that doesn't exist. On the other hand, in the case of the configuration of this embodiment, it can be seen that the range of the defocus amount where good cutting is possible exists on the negative side as well as the positive side. Therefore, in the configuration of this embodiment, even when the set defocus amount during cutting is set to the negative side, that is, the focal point 9 is set below the surface 6a of the workpiece 6, good cutting can be performed. This is possible.

On the other hand, typical data showing the relationship between the set defocus amount during piercing and the time required to penetrate the workpiece is shown in FIG. In this case, the time required for penetration is plotted on the vertical axis, and the set defocus amount is plotted on the horizontal axis.

In FIG. 3, as the set defocus amount goes from the plus side to the minus side, the time required for penetration becomes shorter, but remains almost constant after zero. That is, it can be seen that the defocus amount that shortens the time required for piercing is on the negative side from zero.

Therefore, by adopting the configuration of this embodiment, the set defocus amount for cutting that allows for good cutting as described above can also be on the negative side, the same as the defocus amount that shortens the time required for piercing. Since it can be set, there is no need to change the defocus amount even when piercing and cutting are repeated, and the time required for piercing can be shortened, so cutting can be performed efficiently. be.

[0020] In the above-mentioned embodiment, the case where one auxiliary lens 8 with a long focal length is interposed in the light transmission system 7 is exemplified, but a combination of a plurality of lenses may be interposed.

[0021]

[Effects of the Invention] As is clear from the above description, according to the present invention, an auxiliary lens with a long focal length is interposed in the optical transmission system between the laser oscillator and the condenser lens in the processing head. This makes it possible to perform cutting by setting the optimum value of the defocus amount during cutting to the same negative value as the optimum value of the defocus amount during piercing. This eliminates the need to change the amount of defocus between piercing and cutting, making it possible to perform piercing in a short time, making cutting more efficient.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing one embodiment of the present invention.

[Figure 2]
Diagram showing the relationship between defocus amount and cutting performance during cutting

[Figure 3] Diagram showing the relationship between the amount of defocus during piercing and the time required for piercing

[Explanation of symbols]

1 is a laser oscillator, 2 is a laser beam, 4 is a processing head, 5
6 is a condensing lens, 6 is a workpiece, 7 is a light transmission system, 8 is an auxiliary lens, and 9 is a condensing point.

Claims (1)

[Claims] Claim 1: A laser beam emitted from a laser oscillator is guided to a processing head via an optical transmission system, and is irradiated onto the workpiece through a condensing lens provided in the processing head. In a laser processing machine for cutting a workpiece, an auxiliary lens with a long focal length is interposed in the light transmission system, and the focus point of the laser beam by the condenser lens is set from the surface of the workpiece. A laser processing machine characterized by being set to face downward.