JPS6316890A - Monitoring device for lens for laser beam machining - Google Patents

Abstract

PURPOSE:To discover an abnormality earlier and to improve the life of a lens and the product yield by monitoring the power of a laser light by the power damper installed at the position far from the imaging focus position of a condensing lens and a burn pattern device. CONSTITUTION:The laser energy existing in the state of being under the peripheral temp. thermally is collected by projecting on the body 7 to be irradiated employing a burn pattern by a condensing lens 2. A laser light 1 is then projected on the center of the power damper 3 which is installed just under the laser light 1 passing through the condensing lens 2 moving a moving frame 6. The oscillator is stopped after the temp. of the condensing lens 2 reaching to a saturation, and the laser energy is collected similarly to a saturation, and the laser energy is collected similarly by the body 7 to be irradiated for burn pattern collection in a short time. two ways of the collected burn pattern are compared with the preset allowable value to decide the deterioration state of the lens. With the device of this composition the life of the lens can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a technique for predicting wear and damage of lenses for laser processing.

[Conventional technology]

FIG. 3 is a schematic diagram for explaining the operation mode of a conventional laser processing lens. In FIG. 1, 1 is a laser beam,
2 is a condensing lens for processing. As shown in Figure 3,
A laser beam 1 (not shown) is transmitted from a laser oscillator, is condensed by a condenser lens 2, passes through an optical path shown by a solid line in FIG. 3, and is focused at a focal point, position A. Here,
A workpiece (not shown) is placed at a focal length f near the focal point A, and the workpiece is laser-processed.

However, if the power density of the laser beam 1 to the condenser lens 2 is larger than a predetermined value, or if there is a thermal influence from the workpiece, or if there is a problem (not shown) provided between the condenser lens 2 and the workpiece, The surface of the condenser lens 2 may become dirty due to spatter during processing (especially common during welding) that enters from the workpiece side through the nozzle hole and adheres to the condenser lens 2. , the coating film on the surface of the condenser lens 2 deteriorates, resulting in a high heat absorption rate. When the heat absorption rate of the condenser lens 2 increases in this way, for example, initially, the normal 0.3 When the heat absorption rate reaches around 0.5%, the condensing lens 2 is heated and a so-called thermal lens effect occurs, causing the condensing lens 2 to swell as shown by the dotted line in Figure 5g3. By shortening the focus of the condensing lens 2 in this way, the laser beam 1 passes through the optical path shown by the dotted line in the third frame and focuses at the focal position B. Therefore, the focal position A When the workpiece is installed at As a result, the condensing diameter and focal depth of the laser beam 1 on the workpiece change, and the irradiated laser energy density becomes smaller.For this reason, the permissible laser energy density may vary depending on the processing application of the workpiece. The limit becomes narrower, causing defects in the machining result.The thermal lens effect described above progresses over time as the machining time for the workpiece increases.

[Problem that the invention seeks to solve]

Since the conventional laser processing lens described above exhibits the operation mode described above, it is necessary to judge from the processing result of the workpiece and replace the condenser lens 2 as appropriate to perform laser processing. It must be made. For this reason, the processing yield for the workpiece deteriorates, and no measures can be taken to extend the life of the expensive condensing lens 2. Therefore, it is necessary to perform periodic cleaning at an early stage, and the operation There were problems such as the process becoming complicated.

This invention was made to solve these problems, and it is possible to detect the deterioration of the condenser lens at an early stage and use it as a means to extend the life of the condenser lens. The object of the present invention is to obtain a lens monitoring device for laser processing that can measure improvements.

[Means for solving problems]

The laser processing lens monitoring device according to the present invention installs an o-war damper at a position farther from the focal point of the condensing lens, and detects the laser noswer energy distribution at a position also at a farther distance. It is equipped with an irradiated object for collecting burn patterns.

[Effect]

In the laser processing lens monitoring device of the present invention, the power damper receives and absorbs the laser energy passing through the condensing lens, and after the thermal saturation time of the condensing lens has elapsed,
The laser energy distribution is measured using the irradiated object for collecting the burn pattern, and compared with the laser energy distribution in the thermal initial state of the condenser lens to determine the state of deterioration of the condenser lens.

〔Example〕

FIGS. 1(a) and 1(b) are schematic diagrams for explaining the operation mode of a laser processing lens monitoring device, which is an embodiment of the present invention. In the figure, 1 Haresa light,
2 is a condensing lens for processing, 3 is a power damper ξ, 4, 5
1 is a cooling water inlet and a cooling water outlet of the power damper 3, 6 is a movable stand, and 7 is an irradiated object for collecting a burn pattern, which is made of an acrylic resin plate or the like.

FIG. 2 is a characteristic diagram showing the relationship between the irradiation time of the laser beam to the condenser lens and the saturation temperature in the laser processing lens monitoring device shown in FIGS. 1(a) and 1(b).

Next, the operation of the lens monitoring device for laser power processing, which is an embodiment of the present invention, will be explained. First, Figure 1 (
As shown in al, the object 7 for collecting the burn pattern is irradiated with laser energy in the current state, which is thermally at ambient temperature, by the condenser lens 2 and collected. The reason why the irradiation position is located below the focal point of the condenser lens 2, as shown in Fig. 1(a), is to facilitate the collection of the burn pattern at a position where the laser energy density is low. Ru. Conversely, if the irradiation position is located above the focal position of the condenser lens 2, measurement becomes difficult. Next, the first
When the movable frame 6 is moved to the position shown in FIG. 6(b), the center position of the power damper 3 comes to be in the direct line F of the laser beam 1 passing through the condenser lens 28.

At this position, the power damper 3 is irradiated with the laser beam 1 until a predetermined time when the laser beam 1 reaches temperature saturation during the passage time of the laser beam 1 through the condenser lens 2 (same as the irradiation time of the laser beam 1 to the solar damper 3). . During this time, the power damper 3 receives and receives laser energy, and heat is removed by the cooling water circulated by each cooling water port 4 and cooling water outlet 5.

This situation is shown in the characteristic diagram of FIG. 3, where the current temperature T of the condensing lens 2. (approximately equal to the ambient temperature) is the saturation temperature T after the irradiation time t8 of the laser beam 1, (usually T8
(several seconds to several tens of seconds). Therefore, after making sure that the condenser lens 2 has sufficiently reached the saturation temperature TBj, the movable frame 6 is moved again to the position shown in FIG. 1(a).
Laser energy is collected again by the irradiated object 7 for burn pattern collection in a short time compared to when the saturation temperature T8 of the condenser lens 2 decreases. In this case, the laser oscillator must be stopped once. Condensing lens 2
Depending on the state of deterioration, the heat saturation time and temperature will be inferior, but
There is no problem with measurement.

Through the operations described above, the two sampled burn patterns are compared, and the state of deterioration of the condenser lens 2 is determined by examining whether the size of the burn pattern is within a predetermined tolerance. However, if the above tolerance is exceeded, immediately stop the processing, remove the condenser lens 2, clean it, reduce the heat absorption rate, remove attached spatter, and reinstall the condenser lens 2. to perform processing work. In addition, if the condensing lens 2 is significantly deteriorated, it should be replaced. Normally, when the condensing lens 2 deteriorates due to the thermal lens effect, the focused image of the laser beam 1 at the position of the workpiece is shortened due to the short focus of the condensing lens 2, as can be seen from Fig. 3 above. becomes larger, and the laser energy density decreases.

In the above embodiment, the power damper 3 and the irradiated object 7 for burn and a-turn sampling are installed on a common movable pedestal 6, and this movable pedestal 6 is driven by a drive device such as an electric motor or an air cylinder. direction or up and down.

Further, the laser processing lens monitoring device according to the above embodiment is installed at the end of the processing table (not shown) on which the workpiece is mounted, at a position that does not interfere with processing, and the condenser lens 2
Only when monitoring the deterioration state of the processing head (not shown)
It is also possible to move the condenser lens 2 to the monitoring position by other means. Furthermore, the laser processing lens monitoring device according to this invention,
It is also possible to install it near the processing head only when necessary.

In addition, in the above embodiment, the movable frame 6 is shown in FIG.
A series of monitoring operations to move from the position shown in Figure 1 (b) to the position shown in Figure 1 (&) is performed in advance by adjusting the laser irradiation time in Figure 1 (a) and the position shown in Figure 1 (tb). It is more effective to systematically execute the monitoring operation according to the present invention by setting the laser irradiation time at ) and the laser irradiation time at ta in FIG. 1 again using a timer, etc. The reliability of detection and monitoring can be increased.

Further, in the embodiment described above, the object 7 to be irradiated for collecting the burn pattern can be replaced manually each time the laser beam 1 is irradiated.

〔Effect of the invention〕

As explained above, in a laser processing lens monitoring device, the present invention includes a power damper located at a distance farther than the focal point imaging position of the condensing lens, and a laser power energy distribution at a position also located at a farther distance. Since the structure is equipped with an irradiated object for collecting burn patterns for detection, it is possible to detect deterioration of the condenser lens at an early stage and provide a means for extending the life of the condenser lens.
It is possible to improve the processing yield of the workpiece,
This provides an excellent effect of providing a highly reliable laser processing lens monitoring device that is extremely simple to operate.

[Brief explanation of drawings]

FIGS. 1(a) and (bl) are schematic diagrams for explaining the operation mode of a laser processing lens monitoring device, which is an embodiment of the present invention, and FIG. (b)
FIG. 3 is a characteristic diagram showing the relationship between the irradiation time of the laser beam and the saturation temperature for the condensing lens in the laser processing lens monitoring device of 2005, and FIG. 3 is a schematic diagram for explaining the operation mode of the conventional laser processing lens. . In the figure, 1... laser beam, 2... condensing lens,
3...Power damper, 4...Cooling water inlet, 5...
cooling water outlet, 6... movable stand, 7... irradiated object for collecting burn pattern. In each figure, the same reference numerals indicate the same or similar parts.

Claims (3)

[Claims] (1) In a laser processing machine that focuses laser light with a processing lens and irradiates it onto a workpiece, and performs processing such as welding on the workpiece, from the focal position of the focusing lens A lens monitoring device for laser processing, characterized in that it is equipped with a power damper and an irradiated object for collecting burn patterns at a far distance position. (2) The laser processing lens monitoring device according to claim 1, wherein the power damper and the object to be irradiated for collecting burn patterns are mounted on a common pedestal. (3) The laser processing lens according to claim 2, wherein the common pedestal is equipped with a drive device such as an electric motor or an air cylinder for moving the pedestal horizontally or vertically. Monitoring equipment.