JPS5933476B2 - How to inspect the cutting condition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for inspecting the state of cutting in cutting using a laser beam or the like.

. Regarding the conventional inspection method of this kind, Figure 1A and Figure 1
This will be explained using Figure B. In FIGS. 1A and 1B, 1 is a laser beam for cutting, 2 is a metal plate to be processed, and 3 is heated and melted by the laser beam 1 at a high speed from a gas injection nozzle 5. Spatter blown away by the flowing gas, 4 is a photosensor such as a photodiode or a solar cell. In Fig. 1A, the sensor 4 is connected to the metal plate 2.
Figure 1B shows a state in which it is disposed only on the back side, and only on the front side in Fig. 1B. Next, the operation will be explained.

In the state shown in FIGS. 1A and 1B, by irradiating the workpiece 2 with the laser beam 1, the heated and melted metal is separated from the metal plate 2 as spatter 3 by the gas flow from the injection nozzle 5. Cutting of the metal plate 2 is achieved. In the state shown in FIG. 1A, the amount of light emitted by the sputter 3 is measured by the photosensor 4 placed below the metal plate 2. In addition, the state shown in FIG. 1B is
This is a case where the photosensor 4 is placed above the metal plate 2, and the amount of light emitted by the molten metal on the surface of the metal plate 2 is measured. Since the conventional cutting state inspection method is performed as described above, the method shown in FIG. 1A measures the amount of spatter 3, and the method shown in FIG. Since only the amount of metal is detected and measured, it is insufficient for inspecting the state of cutting, and the data is insufficient for complete inspection, so there are problems in that it is not suitable as an inspection method.

This invention was made to eliminate the above-mentioned drawbacks, and it involves installing a plurality of sensors that detect light or temperature at appropriate positions on the front and back sides of the workpiece, and simultaneously observing the sensor output signals. The purpose of the present invention is to provide a cutting state inspection method that allows highly accurate inspection.

An embodiment of the present invention will be explained below with reference to the figures.Second
The figure shows one embodiment of the present invention, in which 4a is placed above the metal plate 2 and has a highly directional photosensor 4b for detecting the amount of light generated from the molten metal on the surface; 4d are photosensors that are arranged at predetermined intervals below the metal plate 2, that is, on the back side, and have excellent directivity characteristics like the photosensor 4a. Note that the same or corresponding parts as in FIG. 1 are given the same reference numerals. Moreover, FIG. 3 shows the time course of the output of each photo sensor. Next, the operation of the embodiment apparatus shown in FIG. 2 will be explained. in general,
It is known that when a metal plate is cut with a laser or the like, the spatter scattered below the metal plate has directionality. The directionality of this spatter scatters varies slightly depending on the board thickness, but it is 2 to 3 m7! In the case of a thin plate of about L size, the cutting width is narrow,
Moreover, when cutting is performed to obtain so-called good cutting quality, such as less dross adhering to the back surface of the metal plate, the scattering angle of most of the spatters does not exceed 10 degrees.
Furthermore, when cutting is performed in a manner that results in a so-called poor quality state in which a large amount of dross adheres to the back surface of a metal plate, the angle at which spatter is scattered tends to become extremely wide. Utilizing this feature, photo sensors with excellent directivity are arranged above the metal plate, that is, on the front side where the beam is irradiated, and below, that is, on the back side, as shown in Figure 2, and the metal plate is laser cut. FIG. 3 shows the time course of each photo sensor output observed using a synchroscope or the like. Here, in FIG. 2, the photo sensor 4c is kept at an appropriate distance from directly below the axis of the laser beam, and
The angles θ1 and θ2 formed by the photo sensors 4b and 4d with respect to the fused portion of the metal plate and the beam axis are desirably set within 30 degrees, respectively. In FIG. 3, irradiation of the laser beam is started at time 0, and the surface of the metal plate 2 begins to be heated and melted.

At this time, the photo sensor 4a placed above the metal plate 2
The output of the molten metal begins to rise rapidly, and at the same time as the molten metal scatters as spatters to the back side of the metal plate 2, the output suddenly falls. Next, when the spatter 3 is scattered, the photo sensor 4b
~4d detects the light from the spatter, and its output increases. Thereafter, when the metal plate 2 is moved at a predetermined speed, the outputs of the respective photo sensors 4a to 4d become stable after a predetermined time has elapsed. Here, good cutting quality can be obtained when the output of the photo sensor 4a is maintained at the lowest level, the output of the photo sensor 4c is higher than the outputs of the photo sensors 4b and 4d, and the difference δ between the two is maximum. By simultaneously observing the outputs of a plurality of photo sensors disposed at appropriate positions on the front and back sides of the metal plate in this manner, the cutting state can be inspected with high precision. In addition, in the above-mentioned embodiment, the case where the processing is performed using the laser beam 1 as the cutting beam is illustrated, but the inspection method of the present invention can also be applied to the case where cutting is performed using plasma or gas, and the above-mentioned embodiment It has the same effect as.

Furthermore, in the above embodiment, one photo sensor was used on the beam irradiation side of the metal plate and three photo sensors were used on the back side of the metal plate, but it is also possible to use at least one photo sensor on the front side and two photo sensors on the back side. Bye. Furthermore, a non-contact thermometer or the like may be used instead of the photo sensor. As described above, according to the present invention, at least one sensor is arranged at an appropriate position on the beam irradiation side of the metal plate, and at least two sensors are arranged at appropriate positions on the back side of the metal plate, and these sensors are arranged at appropriate positions on the back side of the metal plate. The present invention is configured so that the outputs of the two are simultaneously observed using a synchroscope or the like, so the cutting state can be inspected more accurately than the conventional method.

[Brief explanation of the drawing]

1A and 1B are schematic cross-sectional views for explaining a conventional inspection method, FIG. 2 is a schematic cross-sectional view for explaining an inspection method according to an embodiment of the present invention, and FIG. FIG. 2 is an output waveform diagram of the sensor in the embodiment shown in FIG. 2; In the drawings, the same or corresponding parts are denoted by the same reference numerals. 1... Beam, 2... Workpiece, 4a
~4d...Sensor.

Claims (1)

[Claims] 1. A cutting beam is irradiated along the planned cutting line of the workpiece, and a sensor that detects light or temperature is placed at an appropriate position on the surface of the workpiece that is irradiated with the beam. At least one sensor and at least two sensors are disposed at appropriate positions on the back surface of the workpiece, and the cutting state of the workpiece is inspected by simultaneously observing the output signals of the plurality of sensors. A method for inspecting cutting conditions. 2. The cutting state inspection method according to claim 1, characterized in that a laser beam is used as the cutting beam. 3. A cutting state inspection method according to claim 1 or 2, characterized in that the sensor disposed on the back surface of the workpiece is disposed within 30 degrees from the extension line of the planned cutting line. .