Plastic and nonmetallic article shaping or treating: processes – Laser ablative shaping or piercing
Reexamination Certificate
1998-07-08
2001-06-26
Silbaugh, Jan H. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Laser ablative shaping or piercing
C219S121620, C219S121730, C219S121760, C425S174400, C425S385000
Reexamination Certificate
active
06251328
ABSTRACT:
DESCRIPTION
1. Technical Field
The present invention relates to a device and a process for using laser diode radiation for shaping work pieces.
2. State of the Art
German patent document 43 16 829 discloses a generic type of process which was radiation for processing material, employing a multiplicity of diodes, preferably diode arrays arranged in groups, for processing work pieces. Using laser diodes for this type of work piece processing has the advantage over using conventional CO
2
—, excimer and Nd-YAG lasers of reducing the complexity, time consumption and expense of these types of operating systems. Moreover, the cost and complex maintenance is considerably less than in the aforementioned laser systems.
The aforementioned German patent document discloses that, for controlled shaping of work pieces, the radiation energy of the laser diode acting on the work piece is controlled in dependence on the temperature distribution spreading over the surface of the work piece. In this way, the temperature distribution is determined in brief intervals and subsequently correspondingly brief influence is exercised on the diode output power and therewith on the beam profile. However, by simply determining the thermal conditions on the surface of the work piece, the momentary state of shaping of the to-be-processed work piece cannot be ascertained or only roughly so that only insufficient data are obtained concerning the further treatment of the work piece with laser light in order to obtain the desired degree of shaping. Furthermore, the laser light generated by the laser diodes is transmitted to the surface of the to-be-processed work piece with the aid of optical transmission elements using optical lenses or optical fiber cables, which entails a considerable loss of power.
DESCRIPTION OF THE INVENTION
The object of the present invention is, therefore, to provide a device and a process for shaping work pieces using laser diode radiation in such a way that, first, the processing procedure runs in a controlled manner until a desired final shape of the work piece has been obtained, so that a precise final shape is produced, and, secondly, that the optical setup contains as few as possible loss-producing components. Thus, the effectivity of the laser diodes remains as unhampered as possible.
A solution to the object of the present invention comprises a multiplicity of laser diodes, a detector unit for determining the spatial shaping of a workpiece and an evaluation and control unit which determines process parameters in dependence on a comparison of the actual state of shaping and a must state of shaping.
The present invention is based on the concept of providing online control with which the actual state of shaping is spatially/geometrically determined after each action of light and, in dependence thereof, the intensity of the laser light radiation impinging upon the work piece to be shaped is pinpointedly controlled.
An element of the present invention is that a device using laser diode radiation for shaping work pieces is provided with a multiplicity of laser diodes disposed over and according to the contour of the to-be-shaped work piece in such a manner that the laser light acts directly on the surface of the work piece. Following brief action of light on the work piece, the work piece deforms locally due to thermally induced material tensions. A detector unit determines the current state of spatial shaping of the work piece, by way of illustration with the aid of a holographic device. The spatial data of the shaped work piece gained with the detector unit are compared by an evaluation and control unit with a stored must state of shaping and the new process parameters required for triggering the laser diode are determined. Therefore, for further illumination of the work piece by the laser diodes the respective output power is controlled including the relative velocity between the laser diodes and the work piece, that is the spatial position of the laser diodes to the work piece.
With the aid of the invented control circuit, a must shaping state is produced in finite iteration steps based on the comparison of the current spatial configuration of the work piece, the so-called actual state, and the desired final state, the so-called must state. Constant comparison of the actual and the must state of the real geometric states is simply essential, because unknown internal stress can be present within the work piece causing the shaping process to run uncontrolledly. With the aid of the invented device and the process that can be conducted therewith, a controlled online process becomes feasible which individually controls, in dependence on the individual shaping behavior of the to-be-processed work piece, preferably the laser diode output power for the subsequent illumination process.
REFERENCES:
patent: 3627989 (1971-12-01), Heidler et al.
patent: 4878225 (1989-10-01), Aiba et al.
patent: 4952789 (1990-08-01), Suttie
patent: 4963714 (1990-10-01), Adamski et al.
patent: 5228324 (1993-07-01), Frackiewicz
patent: 5446258 (1995-08-01), Mordlike
patent: 5578229 (1996-11-01), Barnekov et al.
patent: 5777742 (1998-07-01), Marron
patent: 40 10 054 (1991-10-01), None
patent: 0 317 830 (1989-05-01), None
patent: 62-110883 (1987-05-01), None
patent: WO 94/26459 (1994-11-01), None
Beyer Eckhard
Krause Volker
Kuepper Frank
Treusch Hans-Georg
Wissenbach Konrad
Evenson, McKeown, Edwards & Lenahan P.L.L.C.
Fraunhofer-Gesellshcaft zur Foerderung der angewandten Forschung
Silbaugh Jan H.
Staicovici Stefan
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