AU623417B2

AU623417B2 - Process and device for machining workpieces using a laser beam

Info

Publication number: AU623417B2
Application number: AU38690/89A
Authority: AU
Inventors: Klaus Behler; Eckhard Beyer; Gerd Herziger
Original assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Current assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Priority date: 1988-07-15
Filing date: 1989-07-14
Publication date: 1992-05-14
Anticipated expiration: 2009-07-14
Also published as: WO1990000458A1; EP0350942A1; BR8907546A; EP0350942B1; EP0425531A1; ATE88666T1; DE3824048C2; ES2040418T3; RU2008179C1; AU3869089A; DE3824048A1; ZA895374B

Abstract

In a process for machining workpieces using a laser beam, optical and/or acoustic signals generated in a machining region are recorded and used to obtain actual values which are compared with corresponding reference values of a processing diagram specific to the material and to the machining. The results of the comparison are used to control the machining process by influencing it in a predetermined manner. In order to influence the machining region with a process gas in an appropriate and cost-effective manner, process gas is supplied to the monitored machining region in which the optical and/or acoustic signals are recorded, and the type of process gas and/or at least one gas supply parameter are continuously adjusted.

Description

OPI DATE 05/02/90 APPLN. ID 38690 89 AOJP DAT-z 010 PCT NUMBER PCT/DE89/00465 PCT 1 INTERNATIONALE ANMBU ,IJ LIC TN H DEM VERTRAG UBER DIE INTERNATIONALE ZUSAMMENARBEIT AUDE GE T DES PATENTWESENS (PC-I) (51) Internationale Patentklassiikation 5 (11) Internationale Verdffentlichungsnummer: WO 90/00458 B23K 26/00, 26/12 Al (43) Intemnationales Verbffentlichungsdatum: 25, Januar 1990 (25.01.90) (21) Internationales Aktenzeichen: PCT/DE89/00465 (74) Anwalt: PATENTSTELLE FOR DIE DEUTSCHE FOR- SCHUNG DER FRAUNHOFER-GESELLSCHAFT (22) Internationales Anmeldedatum: 14. Juli 1989 (14.07.89) Leonrodstrage 68, D-8000 Mfinchen 19 (DE).

Prioritiitsdaten: (81) Bestiminungsstaaten: AT (europiiisches Patent), AU, BE P 38 24 048.3 15. Juli 1988 (15.07.88) DE (europiiisches Patent), BR, CH (europdisches Patent), DE (europilisches Patent), FR (europiiisches Patent), GB (europiiisches Patent), IT (europiiisches Patent), LU (eu- (71) Anmelder: FRAUNHOFER-GESELLSCHAFT ZUR ropaisches Patent), NL (europiiisches Patent), SE (euro- FORDERUNG DER ANGEWANDTEN FOR- p~iisches Patent).

SCHUNG E.V. [DE/DE]; Leonrodstrage 54, D-8000 Milnchen 19 (DE).

Veriiffentlicht (72) Erfinder: BEYER, Eckhard Maarweg 17, D-5 100 Aachen Mit internationalem Recherchenberich.

BEHLER, Klaus Schleckheimer Str. 184, D-5 100 Vor Ablauf derfar4nderungen der Anspriche zygelassenen Aachen HERZIGER, Gerd Lendbachstralle 40 a, Frist. Veriuffientlichung wird wiederholt falls Anderungen 100 Aachen eintreffen.

(54) Title: PROCESS AND DEVICE FOR MACHINING WORKPIECES USING A LASER BEAM (54) Bezeichnung: VERFAHREN UND VORRICHTUNG ZUM BEARBEITEN VON WERKSTOCKEN MIT LASER-

STRAHLUNG

(57) Abstract ID0I In a process for machining workpieces using aJ laser beam, optical and/or acoustic signals generated L in a machining region are recorded and used to obtain I actual values which are compared with corresponding/ reference values of a processing diagram specific to the

E

material and to the machining. The results of the com- 1 parison are used to control the machining process by Z influencing it in a predetermined manner. In order to 12 influence the machining rgowiha process gas in 7c an appropriate and cost-effective manner, process gas 0. M 1k. 2 issppidtotemoioedmchnn rgo i 2 2 5 I,s ichuplet the picl nore cousicingar reiordd in 3 J M andc the tal of/o prcssisndor ae eastoeda suppleypameterproes contino ajust 2nega suppy paameer ae cntinousy adustd. '2 2 (57) Zusammenfassung Verfahren zumn Bearbeiten von Werkstflcken mit Laserstrablung, mit einer Bearbeitungszone, deren optische und/oder akustische Signale erfaL~t werden, mit denen Istwerte gebildet werden, die mit einem werkstoff- und bearbeitungsspezifischen Proze~diagramm entsprechenden Sollwerten verglichen werden, wonach eine dem Vergleichsergebnis entsprechende Regelang im Sinne einer vorbestimmten Beeinflussung des Bearbeitungsvorgangs erfolgt. Umn eine angepa~te und wenig kostenaufwendige Beeinflussung der Bearbeitungszone mit Prozelgas zu erreich, wird das Verfahren so durchgefifhrt, dagI der auf die Abgabe optischer und/oder akustischer Signale uiberwachten Bearbeitungszone Proze~gas zugefilhrt wird, and dalI durch die Regelung die Art des Prozel~gases und/oder mindestens 'em Gaszufuhrparameter kontinuierlich beeinflu~t wird.

1 PCT/DE 89/00465 PCT 87/21535-ILT A Process and a Mechanism for the Treatment of Workpieces by Laser Irradiation.

Specification Technique The invention concerns a method for the treatment of workpieces by laser irradiation including a treatment zone, in which optical and/or acoustic signals are recorded, yielding actual values which can be compared with the estimated values derived from a material- and treatment-specific process diagram, followed by regulation governed by the results of the comparison, such as to regulate the operation in a predetermined direction.

The Current State of the Art The accumulation of radiation energy in workpieces plays an important role in their treatment by laser irradiation. Such energy accumulation is caused either by the material- and wavelength-dependent absorption of radiation and/or by the abnormal intensity-dependent absorption due to the formation of laser-induced plasmas. Should a defined critical radiation intensity be exceeded, vaporization of the material causes the formation of laser-induced plasma which leads to the erratic multiple melting of the material. Plasma formation can be so intense that, with well-developed radiation absorption by the plasma, shielding of the workpiece occurs. It is well known that the shielding effect of plasmas may be influenced by the use of gasses. Such influence relates to the is 2 recombination of ions and electrons in the plasma.

Recombination reduces the electron densities in the plasma and, since absorption is proportional to electron density, with higher recombination, absorption in the plasma is reduced.

Control over plasma by the use of gasses is achieved by blowing gasses into the treatment zone. The introduction of a gas leads, however, to a significant increase in the cost of treatment. Accordingly, it is desirable to use as little gas as possible. At the same time, it is well established that even a negligible variation in process parameters during treatment leads to the deterioration of the results of treatment, resulting, for example, in a reduction in welding depth and/or enhanced pore formation.

Description of the Invention.

The invention sets itsel- the objective of so improving the above-discussed method as to achieve a costeffective and error-free treatment of workpieces by laser irradiation.

This objective is attained by supplying the processing gas to the treatment zone under monitoring control of optical and/or acoustic signals and, through regulation, ensuring a continuous control over the type of the processing gas and/or at least one gas supply parameter.

Processing gas regulation has been developed in Laccordance with the invention, which can continuously influence 0 all of the recordable phenomena in the treatment zone so that (OA defective treatment is eliminated. All of the optical and/or i i:l: it acoustic signals in the treatment zone produce either a change in the type of processing gas used and/or a change in gas supply. The type of processing gas signifies here the composition of the gas. Thus a gas may denote, for example, a certain specific gas such as helium or argon, or a mixture of gasses whose composition is varied according to requirements.

The parameter: gas supply, signifies everything that follows from the type of the processing gas, for example, the volume of process gasses per unit of time, velocity of the gas inflow, its distribution in the treatment zone and other associated parameters such as the distance over which the gas is supplied to the treatment zone.

The material- and treatment-specific process diagram for the determination of estimated values to be used in regulation includes or takes into account all the process parameters that can lead to changes in the optical and/or acoustic manifestations within the treatment zone, for example the workpiece material, type of treatment, type of laser radiation and its focussing, as well as the geometry of the workpiece, i.e. the path of the laser beam, differences in height or the different composition and laminar stratification of the workpiece and, in addition, feed travel velocities or travel energies.

The process underlying the above discussed technique is known as set out in the standard DE-OS 34 24 825. That process eliminates the negative effects of laser radiation on the results of the treatment by regulating the intensity of the laser so that the plAsma formation or the absorption of the beam by the plasma remain under control. Such regulation must r: follow at very brief intervals in order to avoid the unwanted explosion phenomena in the plasma. Rapid regulation of this kind is not without its problems. By contrast, it may prove advantageous, in the treatment of workpieces where unshielded plasma, which develops in the treatment zone under laser irradiation, needs to be controlled, to employ, for the purpose of such control, a gas which affects the beam absorption by the plasma. This kind of regulation is slower in scope, yet is quite effective, especially at lower welding velocities and higher laser power.

It is also of advantage if one of the gasses supplying the processing energy can be used in the treatment zone. The processing energy thus made available serves to support the treatment processes, for example in cutting. The processing energy is provided through a chemical reaction in a gas or a mixture of gases, depending on regulation in accordance with the invention and in the required volume.

Also of advantage is a design of the embodiment in accordance with the invention such that regulation makes use of one of the gasses entering into the composition of the workpiece material in the treatment zone. In this case, components of the gas are transported to the material under treatment and either deposed therein or brought into reaction with it. Such, for example, is the advantage gained from laser beam refining of the external surface of the workpiece.

It is possible that regulation can serve to achieve control over the treatment such that one or mo-a of the described effects can be attained, viz. control over the plasma i i and/or over the delivery of the processing energy and/or over the composition of the workpiece material.

It is advantageous to employ process diagrams wherein the estimated values, based on the type of the process gas and/or its supply parameters, take into account the timedependence of the laser- and component-specific process parameters. The terms laser-specific and component-specific process parameters signify all the other parameters which need to be taken into account during treatment such as the structure of the workpiece with respect to its shape and dimensions, its travel velocity, as well as laser power and modulation. When these process parameters are taken into account in the processing of the workpieces and the type of the processing gas and/or at least one gas supply parameter are subject to control, mutually combined gas and laser- and material-specific regulation can be achieved. It is possible, for example, to employ the process as set out in DE-OS 34 24 825 for the control of laser intensity and, depending, for example, on laser power altered to this end, to vary the estimated values derived from the type of the processing gas and/or its delivery parameters.

In the embodiment of the invention, the estimated values derivable from a process diagram are continuously monitored for the effect of the type of gas and/or its delivery in the treatment zone and, in the event of deviation in the recorded actual value, the estimated values are matched. This allows even the previously unforseen effects of the treatment to be recorded. The matching of the estimated value can serve in the derivation of a new process diagram.

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:I l'"iili li i Jlor -r.i-lu 6 An optical signal is provided by the continuous recording, integrally or spectrally, of plasma luminosity and ensuing regulation depends on the determination whether the intensity and/or the fluctuations of beamed light and/or the specific spectral lines of this light fall above or below a specified threshold value. Integral recording is performed in this case by, for example, a photo diode whose electrical signal is utilized. Spectral recording is performed, for example, by a filter passing only the light with specific spectral lines, making it possible to determine whether, on the whole, light with a specific spectrum is present and/or whether the intensity of this light lies above or below a certain threshold value. Spectral recording described above is of special significance when time-dependence needs to be established in the processing of a particular workpiece material. Such a task is, for example, set during the throughwelding of laminated materials or in welding together composite materials. A sudden appearance of a specific spectral line indicates that the treatment zone or the welding seam has a desirable or undesirable structure, enabling the requisite regulation.

From the point of view of the above-mentioned optical recorded data it may be advantageous to use the temperature in the treatment zone and/or the motion of the melt bath and/or the paths of emitted sparks in the structure of the optical and/or acoustic signal. The temperature in the treatment zone, for example the ,emperature in the plasma, provides information about the processing condition of the workpiece. For example, anomalies which might appear in the region close to the material's vaporization temperature could be avoided through I" 1 Y~ temperature measurement. The determination of the motion of the melt bath is important for workpiece refining while the spark path can be utilized in assessing the cutting operations.

A mechanism for the treatment of workpieces with laser irradiation, including laser optics, optical and/or acoustic monitoring of the treatment zone, estimated value derivation fron a process diagram, with a computer connected to a detector and to a device supplying the estimated value ego0 and a computer-controlled regulating mechanism wherein the regulation mechanism continuously regulates the treatment with the type and/or the delivery of the process gasses to the S irradiated treatment zone in response to the monitoring of the treatment zone. The regulating mechanism as set out in DE-OS !is 34 24 825 serves to generate the point data needed for the determination of laser beam intensity, for example, those determining the power of the laser. The regulation mechanism in accordance with the invention provides direct control over o S the treatment zone so that the type and the inflow of the processing gas can each be varied in the direction of the desir.ed outcome. The above-mentioned is valid for the type and/or the inflow of the processing gasses in accordance with the process.

The realisation of the mechanism in accordance with the invention includes at least two computer-controlled mixing valve- which are connected via a computer-controlled dosimetric device to one of the gas supply lines terminating n the vicinity of the treatment zone. This mechanism allows I L 7 a one or a number of gasses to be used in the process, singly or in a mixture, in any desired volume. The resulting processing is to9 to9 *9 9 8 computer-controlled thereby ensuring time-dependent operation of the regulating mechanism.

When the gas supply line is made to open into the beam protection nozzle located above the treatment zone, the processing gas can also operate as the shielding gas for the laser optics.

In locating the optical detector as far as possible from the treatment zone, in order to, on the one hand, avoid exposing it to possible damage yet, on the other, to ensure as rapid as possible recording cf processes occurring in the treatment zone, a fibre-optic cable is employed, one end of which is located in the vicinity of the treatment zone and the other connects to the detector located at some distance from the treatment zone.

Brief Description of Figures The invention is elucidated by means of an example of an embodiment of the mechanism in the figure and additional explanatory diagrams. These include: Fig.l a schematic representation of a mechanism embodying the invention, Fig.2 a process diagram, and Figs 3, 3a the dependence of plasma light intensity on time for a determined workpiece geometry.

9 Best Methods for the Embodiment the Invention.

The workpiece 1 undergoes treatment within the zone 2 with laser irradiation 15. The treatment may include for example welding of critical materials such as aluminium or aluminium alloys or laminated materials such as zinc-coated plate. The treatment may also include cutting, for example the manufacture of complicated formed parts, or surface refining such as nitriding of bearing surfaces.

Laser irradiation 15 is beamed at the workpiece 1 by means of the laser-optical system 7 which effects the required focussing. The laser-optical system 7 is enclosed in a beam protecting nozzle 19 which shields the optical system 7 from the reverse action of the gasses and the spray of melt particles of the material and, in addition, provides mechanical protection for the optical system 7.

The treatment zone 2 of workpiece 1 is monitored for optical and acoustic signals. For this purpose, the optical detector 3 and the acoustic detector 3' are used. The optical detector 3 is located at some distance from the treatment zone 2 and comprises, for example, a photo diode. To enable the photo diode to reliably record the optical signals from the treatment zone 2, the detector 3 includes an optical fibre cable 4 whose free end 4' is located in the immediate vicinity of the treatment zone 2. The optical detector 3 thus enables all time-dependent optical signals from the treatment zone 2, such as flash intensities, fluctuations of flash luminosity, ~heat radiation flashes and such like, to be recorded.

The acoustic detector 3' comprises a microphone, for example a condenser microphone, which is protected against effects of action within the treatment zone 2 and can therefore be placed in relative vicinity. The term acoustic signals signifies sound intensity such as noise intensity as well as signal frequency, tone level, frequency or its variations.

The detectors 3, 3' generate electrical signals which are led to the adding device 8' of the computer 8 as actual values 10. The adding device 8' also receives the estimated values 11 enabling the actual-versus-estimated value comparison. Any difference disclosed by the adding device 8', which can also be integrated with the computer 8, is used by the computer 8 to vary, with the aid of reference signals the regulating mechanism 16 which enables continuous control to be maintained over the type or the rate of supply of processing gasses 11, 12, 13, with reference to the monitoring data.

The regulating mechanism 16 consists of a number of mixing valves 6 which deliver supplies of gasses 11, 12, 13.

The delivery is effected through a mixer 5 coupled to a dosimetric mechanism 17. The dosimetric mechanism is likewise a mixing valve and, like the mixing valve 6, is controlled by the computer. The same regulating mechanism 16 also allows the gas 12 and/or gas 13, and/or gas 14 to enter into the mixer likewise under computer control of dosage. The mixer 5 mixes the gasses 12, 13, 14 and delivers a gas-mixture or, given an appropriate setting of the mixing valve 6, delivers a single gas to the dosimetric mechanism 17 which determines the maximum volume of gas per unit of time to be supplied to the treatment zone 2. The delivery is effected through the gas supply lines ii 9. A mechanism for the treatment of work pieces with laser irradiation including laser optics; optical and/or acoustic monitoring of a treatment zone; estimated values derivation from a process diagram with a computer connected to /2 11 18, 18' designed in accordance with requirements. The gas line 18, for example, connects, in accordance with the right hand side of fig. 1, into the beam protecting nozzle 19 so that the processing gas, as well as the shielding gas, can be utilized, thereby ensuring that the operation of the laser optics 7 is not adversely affected ok impaired by the flow towards the treatment zone 2 of opposing currents of gasses and/or particles evolved by the treatment.

In accordance with the left hand side of the representation in fig. 1, the processing gas can also be delivered via the gas supply line 18' to the immediate vicinity of the treatment zone 2, for example in the direction of travel 21, symmetrically ahead of the treatment zone 2. In such case, a symmet- ',al flushing occurs of the treatment zone 2 with the proce j gas while the laser optics 7 is afforded protection by, f-r example, the inflow of the shielding gas through the beam protecting nozzle 19.

The flushing of the treatment zone 2 with gas may also be influenced by altering the flow geometry of the gasses, for example by moving the beam protecting nozzle 19 which supplies the processing gasses. Of significance to the invention is the fact that all the possible parameters should be capable of continuous adjustment with respect to the processing gas being used so that the corresponding effect on the formation of reaction processes in the treatment zone 2 can be assessed, for example the formation of plasma for energy /accumulation in the workpiece I.

J 12 The estimated values 11 are fed to the computer 8 from the material- and treatment-specific process diagram. An example of such a process diagram is given in fig. 2 which shows the value A of the melt specks such as those emitted in the treatmenL zone, as a linear function of travel energy P/v for a carbon dioxide laser in the 2 to 10 kW range and steel as the workpiece material. If. for example, a particular workpiece is being welded with the travel energy of 200J/mm, the melt speck size A might amount to 10mm 2 For the corresponding working datum a in the process diagram shown in fig. 2, the treatment zone 2 shows specific flash phenomena L1 which derive from the plasma originating therein and have been recorded by the detector 3. If the actual value 10 corresponds to the estimated value 11, the computer 8 has no cause to alter the processing gas supply rate that had been selected earlier and implemented by the regulating mechanism 16. Should, however, the welding velocity be reduced, for example while the treatment path involves travel along a bend, the travel energy could rise, for example to 300. The working datum would then be displaced, for example to a' which is associated with flash phenomena L2. By comparison with LI, the flash phenomena L2 are more intense, since a more intensive supply of energy produces more intensive vaporization in the workpiece material and the corresponding enlargement of the plasma. By measuring the signal differences shown in fig. 2, 1 L2 Li, which corresponds to the related change in the actual value 10, the computer can implement control measures over the treatment, based on the results of the comparison such that, for example, the volumes of the processing gasses 12, 13, 14 delivered will be increased by the dosimetric device 17. The processing gas i i 13 enhances the recombination of plasma particles so that energy accumulation in the workpiece 1 is reduced, leading tc a reduction in workpiece material vaporization, and thereby to a reduction in plasma formation and abatement of flash phenomena.

Fig. 2 shows, as an additional parameter, the change in the size of the melt speck A from 10 to 15 mm 2 when the working datum a has been displaced to That change in the size of the melt speck A can also be directly observed and utilized in regulating the process, for example through the use of a video camera equipped with computer-controlled melt speck size determination.

Figs. 3, 3a illustrate the dependence of the flash phenomena in the treatment zone on processing gas flow. Fig. 3a shows the reduction in the flow of the processing gas F of, for example, 30 1/min in 4 seconds to 0. Fig. 3 shows the response reaction of the intensity of argon line in the flash phenomena in th- treatment zone, in the diagram IA It is evident that light intensity suffers a break and simultaneously there occurs a significant rise in the fluctuations of the said flash phenomena. Accordingly, the threshold value la may be used in process regulation, for example to increase the gas inflow. The fluctuations which occur can also be utilized in determining the point in time at which the control over the gas flow must be assumed. This is prompted by the recognition that in the region B of fig. 3, the limit value Ip is obtained from fluctuations which likewise must be discovered by measuring techniques and allow influence to be exerted over the gas flow S Iparameters.

material causes the formation of laser-induced plasma which leads to the erratic multiple melting of the material. Plasma formation can be so intense that, with well-developed radiation absorption by the plasma, shielding of the workpiece occurs. It 01V is well known that the shielding effect of plasmas may be influenced by the use of gasses. Such influence relates to the 14 Understandably, the representations in figG. 2, 3 and 3a, respectively, are valid only for a laser- and/or componentspecified configuration possessing the corresponding process parameters. If, for example, the focussing of the laser beam is altered and with it the beam particle in the treatment zone 2, fig. 2 will have a different appearance. For the derivation of the estimated values 11 it is therefore important that the process diagrams take into account the laser- and/or component-specified process parameters, especially the timedependence. The process therefore also takes account of this time-dependence via the control exerted over the type of the processing gas and/or its delivery.

Experience indicates that the treatment of workpieces also gives rise to effects which can not be accounted for in advance in terms of a process diagram. This leads, for example to a situation in which the working datum a' is displaced, as a result of process gas inflow, not to al, but to This will induce a deviation in the actual value 10 since, for example, the light intensity and/or the welding speck size A at deviate from those at Because the estimated values obtained in advance from the process diagram deviate from those desired for the treatment zone 2, the regulation of the gas parameters allows in this case the estimated value to be correspondingly adjusted. Such adjustment is especially required when the deviations determined persist over time, thus allowing the determination of a mean deviation.

4Y.' 0 V Commercial Exploitability The process in accordance with the invention serves to improve the beam energy accumulation in the workpiece in a manner which makes possible cost-effective and error-free treatment of workpieces with laser irradiation.

Patent rIaim 1. A process for the tre tment of workpieces with laser irradiation, involving a treat ent zone whose optical and/or acoustic signals are recorde and yield actual values which can be compared with estimated alues derived from material- and/or treatment-specific proces diagrams, following which regulation, intended to xert a pre-determined effect on the treatment process and g verned by the results of the comparison, wherein t e processing gasses (12, 13, 14) are delivered to the tre tment zone under the control of the therefrom emitted tical and/or acoustic signals and wherein the regulation of/the type of processing gas (12, 13, 14) and/or of at lea t one gas inflow parameter is continuously effected by reference to monitoring results.

2. A rocess as set out in claim 1, where non-shielding plasma is roduced under laser irradiation in the treatment zone and hich can be controlled by regulation, wherein regulation utilizes one of the gasses (12, 13, 14) that affects beam a sorption by the plasma.

3. A process as set out in claims 1 or 2, wherein use ismade of one of the processing gasses (12, 13, 14) supplied Sthe tr ment on

Claims

1. 11~ ;lll-..;ILL-Ilililii.ii.Lli.-ll 3 j THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:- i. A process for the treatment of work pieces with laser irradiation which includes recording optical and/or acoustic signals from a treatment zone; obtaining actual values from the recorded signals; comparing the actual values with estimated values derived from material and/or treatment specific process diagrams; and regulating the process in response to the comparison wherein processing gases are delivered to the treatment zone under the control of the optical and/or acoustic signals and wherein the type of processing gas and/or at least one gas inflow parameter is ooeo continuously regulated. S

2. A process as set out in claim 1 where non-shielding plasma is produced under laser irradiation in the treatment zone and which can be controlled by regulation wherein regulation utilises one of the gases that affects the absorption by the plasma.

3. A process as set out in claims 1 or 2 wherein one of the processing gases supplies processing energy to the gee• treatment zone.

4. A process as set out in one or more claims 1 to 3 wherein one of the gases affects the composition of the workpiece material in the treatment zone. A process as set out in one or more claims 1 to 4, wherein process diagrams are used, wherein the estimated values, based on the type of the process gas and/or its supply parameters, take into account the time-dependence of the 4- laser- and component-specific process parameters. 'O.Fl Sc v c ur T iiiI c process oiagram are continuously monitored for the effect of the type of gas and/or its delivery in the treatment zone and, in the event of deviation in the recorded actual value, the estimated values are matched. This allows even the previously unforseen effects of the treatment 0 to be recorded.

The matching of the estimated value can serve N in the derivation of a new process diagram. i<! 16

6. A process as set out in one or more of the claims 1 to 5 wherein the estimated values derivab.L from the process diagram are continuously monitored for the effect of the type of gas and/or its delivery in the treatment zone and, in the event of deviation in the actual value, the estimated values are altered to match.

7. A process as set out in one of the claims 1 to 6, wherein the optical signal from plasma flash is continuously recorded integrally or spectrally and regulation of the plasma flash depends on the determination whether the intensity and/or the fluctuations of beamed lights and/or the spectral lines of these lights fall above or below a specified threshold value.

8. A process as set out in one of the claims 1 to 6, tIS" wherein the temperature in the treatment zone and/or the motion of a melt bath and/or paths of emitted sparks are made part of the optical and/or acoustic signal.

9. A mechanism for the treatment of work pieces with laser irradiation including laser optics; optical and/or acoustic monitoring of a treatment zone; estimated values derivation from a process diagram with a computer connected to a detector and to a device supplying the estimated value; and a computer-controlled regulating mechanism wherein the regulation mechanism continuously regulates the treatment with the type and/or delivery of the process gas to the irradiated treatment zone in response to the monitoring of the treatment zone.

A mechanism as set out in claim 9, wherein the 4 icji-:: AX A 17 regulation mechanism has at least two computer-controlled mixing valves which are connected via a computer controlled dosimetric device to a gas supply line terminating in the vicinity of the treatment zone.

11. A mechanism as set out in claim 9 or 10, wherein a gas supply line opens into a beam protection nozzle located above the treatment zone.

12. A mechanism as set out in one or more of the claims 9 to 11, wherein one end of an optical fibre cable conducting the optical signals, is placed in the vicinity of the treatment zone and the other is connected to the detector located at some distance from the treatment zone. DATED this 29th day of January 1992 F'raunhofer-Gesellschaft zur Forderung der angewandten Forschung e.V. By their Patent Attorneys CULLEN CO. 4 *ooo *go oo i ft oo* oo,