METHOD OF CUTTING A MATERIAL BY A LASER MACHINE

Abstract: A method of cutting a material comprises cutting a mate­ rial by laser beams (3) emitted from a laser machine (1), and cleaning a cut surface of the material by water (11) as a solvent.

Description: The present invention relates to a method and a device of cutting a material by a laser beam according to the first part of claim 1 (JP-A-61 286 087). In the method known from the JP-A-61 286 087, a kneading material (a mixture of graphite and powder clay kneaded with methanol) is coated on the backside of the metallic workpiece to be cut. The purpose of this measure is to avoid the adhesion of molten metal at the backside of the workpiece. After cutting the kneaded material and thereby the molten metal is removed from the backside of the workpiece by cleaning with water. In another known method (EP-A-0 060 980), in which sheet metal is cut by a laser beam, water is ejected from a nozzle to the cutting location for cooling the same. Figure 7 shows schematically a further conventional method of cutting a material by using a laser machine. In Figure 7, the cutting of the material has been made by controlling heat to a portion to be processed by adjusting a position of the focal point of laser beans, an output of the laser beams and a cutting speed depending on the material to be processed. In Figure 7, a reference numeral 1 designates a processing head, a numeral 2 designates a focusing lens, a numeral 3 designates laser beams, a numeral 4 designates a focal point and a numeral 5 designates a material to be cut. When the material is to be cut, the focal point of the laser beams moves on the material along a predeternined path due to a relative movement of the processing head to the material to be cut (5), whereby the material is cut in a predetermined shape. The above-mentioned laser bean processing is a method of cutting by utilizing heat. Accordingly, when an inoulatinq material made of paper or the like is to be cut, phenomena that a cut surface becomes dark due to burning and a material at the cut surface is resinified or is chemically changed may cause deterioration in electrical performance, appearance and so on. The chemically changed material is very sensitive to an input heat at the focal point of the laser beams and locally appears due to a change of cutting speed at a curved portion and a change of focal point position which is caused by deformation of the cut material. This reduces the quality of products to be produced. Besides the above-mentioned method by utilizing heat which causes the problem of a chemical change, there has been proposed a method of cutting a material only by a water jet. However, when a material having a large thickness is to be cut, an extremely large propellent force is needed, which inevitably requires a large-sized apparatus and causes burrs or fuzzing at an edge of a cut portion in the cut material. It is an object of the present invention to provide a method of cutting a press board by a laser machine, which is capable of removing a chemically changed portion appearing at a local portion of the press board cut by the laser machine and improving the quality of the products. The foregoing and other objects of the present invention have been attained by providing a method according to claim 1. Whereas the cut surface may be wiped by a meter impregnated material like a sponge, it is more effective to use a water jet in the second step. In the drawings: Figure 1 is a diagram showing an embodiment of the second step in the method of cutting a material according to the present invention; Figure 2 is an electron micrograph of a cut portion without cleaning in cleaning tests; Figure 3 is an electron micrograph of a cut portion cleaned by alcohol in cleaning test; Figure 4 is an electron micrograph of a cut portion cleaned by water in cleaning tests; Figure 5 is a diagram showing a second step of another embodiment of the present invention; Figure 6 is a diagram showing an application of the device as shown in Figure 5; and Figure 7 is a diagram showing a conventional method of cutting a material by a laser machine. Preferred embodiment of the present invention will be described with reference to the drawings. Figure 1 shows in particular a second step of the nethod of the present invention, wherein a reference numeral 6 designates a piece of sponge in a rolled form, a numeral 7 designates a press board made of paper which is cut by a laser machine, a numeral 8a designates a cut surface of the press board which has not been wiped by sponge impregnated with water, a numeral 8b designates a cut portion of the press board which has been wiped by the sponge, and a numeral 9 designates an arrow mark which indicates a direction of wiping by the sponge impregnated with water. The second step is very simple step wherein the end surface cut by a laser machine is wiped by the sponge 6 or cloth impregnated with water. The second step is futurized by using water as a solvent to a substance adhered on the cut surface. It has been a common knowledge that an organic solvent such as alcohol, acetone, or the like has been used as the solvent of this type. The inventors of this application conducted wiping and cleaning tests on end surfaces of samples cut by a laser machine wherein conditions of laser power, a speed of cutting and so on are changed. As a result, it was revealed that water can be effectively used rather than organic solvents in order to wipe and clean the end surface of a press board cut by a laser machine. Figures 2 through 4 show electron micrographs showing the result of wiping and cleaning tests. Each samples as shown in Figures 2-4 was cut under the same conditions, wherein the sample shown in Figure 2 was not subjected to the wiping cleaning operation, the sample shown in Figure 3 was subjected to wiping and cleaning operation with alcohol. In Figure 3, some amount of an adhered material was removed from the cut surface, however, a large portion of the adhered material remained at the cut portion. Figure 4 shows a state of cut portion which was wiped and cleaned by water and shows that fibers of the press board were entirely exposed. In comparison with the electron micro-graphs, it is understood that water is very effective. Thus, the second cleaning step using water as a solvent is an essential element of this invention. Accordingly, it goes without saying that the same effect can be obtained by using a material wettable to water such as cloth, paper or the like in order to supply water to a cut end surface besides of the sponge impregnated with water. Further, it is possible to suppress dust from the material impregnated with water from depositing on the cut surface by using a non-dusting material of sponge, cloth or paper which is usable for a clean room. Further, it is clear that the same effect can be obtained in the second step by using a wet brush. It is preferable that water used for cleaning the end surface of a cut material has to be clean, and more preferably foreign substances have to be removed by a filter before using. Another embodiment of the method of the present invention will be described with reference to Figure 5. Figure 5 shows a cleaning step wherein a reference numeral 10 designates a nozzle for a water jet device, numeral 11 designates water ejected from the nozzle and numerals 51, 52 designates cut portions which have been separated by laser beams in the first step wherein the cut portion 51 is used for a final product. A numeral 12 designates a space produced by cutting the material by the laser beams. The material adhered on the end surface of the cut portion are dissolved and peeled off by the water ejected from the water jet device, and the material can be easily removed from the end surface. Thus, the end surface is cleaned. It is sufficient that only the surface of the cut portion cut by the laser beams is cleaned by the water jet, and it is an unnecessary to give a large jetting force as large as that required to cut by only the water jet. The cut portion 52 as a waste material may be removed before the second step. In the second step, the cutting operation and the removing operation may be simultaneously performed by using a processing machine which is so controlled that the laser beams and the water jet draw the same locus as shown in Figure 6, in order to reduce a time of processing and improve accuracy of water-jetting position in the second step. Thus, in accordance with the present invention which comprises a cutting step and an adhering material removing step, the cut surface can be cleaned and products having a stable electric performance and good appearance can be obtained. Especially, water is used for a solvent in the second step. Therefore, it is safe, economical and easy to use, and it has many advantages. Further, the second step can be continuously performed after the first step by using the water jet. Furthermore, an operating time can be shortened.

Claims: A method of cutting a material by a laser beam (3) emitted from a laser machine (1), in which water is used for a cleaning operation, characterized in that the material to be cut is a press board (7, 5) and in that in a step after cutting, the cut surface (8a) of the press board (7, 5) is cleaned by the water as a solvent. The method according to claim 1, characterized in that the cut surface of the press board is cleaned by ejecting water by a water jet (11). The method of claim 2, characterized in that the water jet (11) is drawn along the path cut by the laser beam (3) simultaneously with and upstream of said laser beam (3) with respect to the processing movement. The method according to claim 1, characterized in that the cut surface (8a) of the press board (7) is cleaned by moving a material (6) impregnated with water along the cut surface (8a). The method of claim 4, characterized in that the material impregnated with water is cloth, sponge or paper.

Inventors: AONO, KAZUAKI, KISHI, AKIO, SHIONO, KATSUMI, YOSHIZUMI, YASUZI
Applicants: MITSUBISHI DENKI KABUSHIKI KAISHA
Application year: 1989
Main classification: B23K26
IPC codes: B23K26