DE10040921A1 - Hand-guided processing head for high power diode laser has protective glass temperature and fouling monitoring with temperature measurement by thermoelement in drawer-like bearer - Google Patents

Abstract

The device has protective glass (3) monitoring with respect to temperature and fouling on the basis of a temperature measurement of the protective glass with a thermoelement (6) in combination with a specially designed drawer-like bearer (5) containing the thermoelement. The measurement values are used to detect satisfactory glass and to control the laser power.

Description

The invention relates to the field of material processing High power diode laser, especially for welding, surface cleaning, Cladding, cutting, drilling, engraving and the like

A hand-held processing head for a high-power diode laser is presented, or other lasers whose wavelengths can be transmitted through optical fibers, which is specially designed for one-handed use.

System components are essentially the processing head mentioned Arrangements for radiation protection, distance regulation and power control depending on the processing speed, a laser source, the power supply with regulation and a safety sensor system.

The prior art in the field in question holds various systems Material processing with hand-held laser processing heads ready, taking under "Hand-held" is mainly to be understood that the laser processing head with hand the workpiece is placed on and by means of a motor-driven drive unit this is led.

However, it seems desirable to have a processing head available that allows free one-handed guidance, d. H. without drive unit for movement the workpiece.

DE OS 42 12 391 presents a laser handpiece for the dental field, in which the outcoupling end of an optical fiber is mounted. The handpiece carries furthermore a focusing and deflection head as well as other elements.

Here it can be assumed that this device is not for the high-performance range is provided and suitable.  

DE 198 39 482 describes a material processing system High-performance diode laser presented, which includes a processing head. The processing head contains all for the high quality execution of the Components of the work process and the protection of the operator.

This processing head is intended by the invention presented below in view on ease of maintenance, protection against stray radiation, speed and Performance control further optimized and also through additional functions in the Use value can be improved.

For this purpose, known ones are absolutely necessary for function and for laser safety Combine elements with inventive features, with the aim of being a handheld device to have free one-handed guidance on the workpiece, which is a mass less than three kilograms.

The hand-held processing head according to the invention has the following components:

• - Ergonomic handle for one-handed use;
• - Fiber coupling in the handle of the processing head;
• - collimation optics for beam bundling;
• - Mirror for deflecting the beam path between 0 and 120 °;
• - Optics to focus the radiation;
• - Camera and optics for process observation, the work area directly can be viewed or preferably tracked on a display on the processing head;
• - Three independent safety circles, namely one Laser release button, which detects whether the machining head rests on the workpiece, furthermore an inductive sensor for metal detection and finally one software-controlled control function using a microcontroller;
• - switch for program selection;
• - processing nozzle;
• - LED ring for illuminating the work area;
• - Brush ring and lamella cover for protection against stray radiation;  
• - Impellers or balls arranged on the nozzle as path or Speed sensor, at the same time as a spacing and control device;
• - Additional wire feed;
• - temperature monitoring of the machining head;
• - protective glass coaxial and cross jet;
• - Status and parameter display on the processing head.

For optimal and safe operation, these are sometimes indispensable or practical.

For further optimization of a hand-held machining head without a motor powered drive unit for a high power diode laser and other lasers, whose wavelengths can be transmitted through optical fibers, is proposed according to the invention, the protective glass in a drawer-like carrier to arrange and to monitor with regard to temperature and degree of pollution, which on Distance or speed transducers arranged for the speed Power control and speed wire feed control and also a movable nozzle attachment for the purpose of dynamic adjustment the scattered radiation protection to the workpiece to be machined in a suitable manner on the Arrange the processing nozzle.

The proposed measures are explained in more detail below:

Protective glass support and protective glass monitoring

With short working distances of laser material processing optics from direct It is imperative to protect the work area from contamination by means of a to keep the protective glass in storage.

Since the pollution absorbs part of the laser radiation and thus the Laser power reduced at the machining site, it is also necessary the degree of contamination of the protective glass, in extreme cases its destruction, to be monitored so that it can be cleaned or replaced in good time.  

For this purpose, it is proposed according to the invention to arrange the protective glass in a carrier. This is for visual inspection for irregularities or for exchanging the Protective glass quickly and easily into the beam path without adjustment Machining optics can be introduced or removed, preferably by means of a Sliding or folding mechanism. The carrier houses a thermocouple for measurement the protective glass temperature. For this purpose, the thermocouple is on or in the contact surface for the protective glass is arranged and has direct contact with this, which makes the Protective glass temperature can be detected immediately.

An example of the equipment design is in the later description text in one Embodiment specified.

The increase in the protective glass temperature after switching on the laser depends on the laser power used is a measure of the degree of contamination or an indication of a defect in the protective glass and can therefore from the signal of the thermocouple be derived. The degree of contamination is determined by means of a suitable display element and / or the temperature of the protective glass can be represented by the operator and can be interpreted accordingly. The laser power is expediently in Dependence on the determined degree of contamination of the protective glass with regard to constant range of services regulated at the place of work.

The soiled protective glasses are thus without significant impairment of the Processing quality can be used for longer.

The processing laser is switched off when a critical temperature is exceeded. This will destroy the protective glass and the optics behind it prevented.

The presented measurement of the protective glass temperature compared to previously used Systems that vary the degree of pollution via the emerging radiation Wavelength determine a robust, insensitive to impurities Protective glass monitoring.

The protective glass support is advantageously made of a poorly heat-conducting material manufactured. This achieves thermal decoupling of the protective glass from the parts heated during the machining process, for example the machining nozzle.  

This has the advantage that measurement errors are avoided and the thermal voltages be reduced in the protective glass.

Finally, the protective glass support contains a locking mechanism. This is advantageously designed so that it makes electrical contact with the Thermocouple closes only when there is a protective glass in the carrier and this is correctly inserted into the optical beam path. Thus, the contact of the Thermocouple can determine whether a protective glass is properly in the processing head rests.

Speed power control

The speed power control proposed according to the invention is on Processing head of a laser welding device realizes and enables this Manual laser welding with high-power diode lasers as well as other laser sources. The power control is based on the travel speed of the machining head on the workpiece, through a kind of value assignment, in which experimentally determined characteristic curves or calculated characteristic curves are used. Without this control, laser-friendly welding would not be possible by hand. First, the processing or travel speed is individual different ways, depending on the operator. There are none Motor-driven axes. The speed is non-contact via a optical system or touch using a mechanical device. A microcontroller in the processing head takes over the signal processing. The signal evaluation results in a control signal which defines the relationship between the Laser power and the feed rate describes.

The control takes place within a speed interval in which a change the speed of travel causes a change in the laser power.  

The characteristics of the laser power depending on the speed, either were calculated or determined from experiments, with variation of the Process parameters, for example material type or material thickness, from the program memory queried. The control signal determined serves to change the laser power. The speed-power control described is not on this specific one Limited use case. It is in connection with other laser systems, for example those with solid-state lasers, hand or machine-guided, can also be used for other purposes.

Speed filler wire feed control

The speed wire feed control is like the speed Power control in or on the processing head of a mobile laser welding machine realized. It enables laser manual welding with filler material based on High power diode lasers and other laser sources.

The additional wire feed control is based on the travel speed of the Machining head on the workpiece.

The basis for the speed wire feed control is a kind of value assignment, in the case of previously determined characteristic curves or calculated characteristic curves be used.

First of all, the processing or travel speed is set individually by the operator specified. No axes are motor-driven.

The speed is contactless via an optical system or touching a mechanical device added. One in the processing head Microcontroller handles signal processing.

The result of the signal evaluation is a control signal, which shows the relationship between Additional wire feed and travel speed are described.

The control takes place within a speed interval in which a change the travel speed causes a change in the additional wire feed.  

The characteristics of the additional wire feed depending on the speed, which have either been calculated or determined from experiments are modified when the Welding parameters, for example the type, thickness or gap width, queried from the program memory. The signal determined is used to control the Additional wire feed unit, consisting of motor, wire guide system and wire supply. The speed wire feed control can also be used in conjunction with other laser systems, for example with solid-state lasers, are used either are hand or machine-operated.

The invention is explained in more detail below on the basis of exemplary embodiments. Several drawings are used for this.

In Fig. 1, a solution of apparatus is specified for a laser safety glass support.

Fig. 2 is a schematic diagram for the speed power control and Fig. 3 shows one for the speed wire feed control.

The reference symbols used mean:

1

Laser,

2

Processing optics,

3

Protective glass,

4

lock

5

Protective glass support,

6

Thermocouple,

7

machining nozzle,

8th

transducer,

9

microcontroller,

10

Sensor,

11

D / A converter,

12

incremental,

13

Additional wire release elements,

14

Filler wire feed unit,

15

Elements for communication,

16

Elements for laser release,

17

Elements for laser safety,

18

Elements for status and parameter display,

19

Power adapter.

First of all, an example of a protective glass support is given in connection with a protective glass monitor. The protective glass support is shown graphically in FIG. 1.

This essentially consists of the carrier 5 for the protective glass 3 , a thermocouple 6 and a lock 4 .

The thermocouple 6 is fastened to the carrier 5 in such a way that it lies directly against the protective glass 3 when it is inserted. In addition, the protective glass 3 is secured by means of the lock 4 , which is designed in a manner customary in the art. It helps to ensure that the protective glass 3 lies correctly on the thermocouple 6 or is positioned in the carrier 5 .

The entire unit can be inserted into or removed from the processing nozzle 7 by moving it. A folding mechanism would also be conceivable for this. Reference is made to the preceding description of how the protective glass monitoring works.

A speed power control is implemented as already described.

Fig. 2 shows a schematic diagram for this.

The control consists of a microcontroller 9 for signal processing, evaluation and generation, a D / A converter 11 and an incremental encoder 12 as a central unit.

The incremental encoder 12 receives signals from a displacement sensor 8 in the selected example in the form of an impeller in conjunction with a sensor 10 .

The microcontroller 9 is assigned elements for communication 15 in the form of a programmable logic controller. It provides information to elements for laser release 16 , laser safety 17 and status and parameter display 18 . The D / A converter is connected to a power supply 19 .

Active connections to the laser driver, the laser source and the processing nozzle 7 are thus established via the elements mentioned.

The speed wire feed control is basically the same. Here, the D / A converter 11 outputs the control signal to the additional wire feed unit 14 . The microcontroller 6 additionally outputs information to elements for the additional wire release 13 .

A basic sketch for this is given in FIG. 3.

The displacement and speed sensors are located at the end of the processing nozzle 7 .

On this is a movable nozzle attachment for the purpose of dynamic adjustment of the Scattered radiation protection arranged on the workpiece to be machined.

Claims (10)

1. Hand-held processing head for a high-power diode laser, which contains the components listed below either mandatory or optional

• - Ergonomic handle for one-handed guidance,
• - fiber coupling in the handle of the processing head,
• - collimation optics for beam bundling,
• Mirrors for deflecting the beam path between 0 and 120 °, optics for focusing the radiation,
• - Camera and optics for process observation, whereby the work area can be viewed directly or is preferably shown on a display on the processing head,
• Three independent safety circuits, namely a laser release button that detects whether the machining head rests on the workpiece, an inductive sensor for metal detection and finally a software-controlled control function using a microcontroller,
• - switch for program selection,
• - machining nozzle,
• - LED ring for illuminating the work area,
• - Brush ring and lamella cover for protection against stray radiation,
• - On the nozzle arranged impellers or balls as a displacement or speed sensor, at the same time as a spacing and control device;
• - additional wire feed,
• - temperature monitoring of the machining head,
• - protective glass coaxial and cross jet,
• - Status and parameter display on the processing head,

characterized in that protective glass monitoring with regard to temperature and degree of contamination is implemented on the basis of the temperature measurement of the protective glass by means of a thermocouple ( 6 ) in conjunction with a specially designed drawer-like carrier ( 5 ) which contains the thermocouple ( 6 ), the measured values being used for detection the properly inserted protective glass ( 3 ) and to control the laser power,
that a speed power control is provided, in which the speed individually specified by the operator is compared with previously experimentally determined or calculated characteristic curves of the laser power as a function of the travel speed in a microcontroller ( 9 ) and processed to form a control signal which within a speed interval Change in laser power causes
that a speed additional wire feed control is provided in which the speed individually specified by the operator is compared with previously experimentally determined or calculated characteristic curves for the additional wire feed as a function of the travel speed in a microcontroller ( 9 ) and processed into a control signal which is generated within a speed interval causes a change in the additional wire feed,
that the displacement or speed sensors are arranged at the end of the processing nozzle ( 7 )
that a movable nozzle attachment is available for the purpose of dynamically adapting the anti-scatter protection to the workpiece to be machined
and that the processing head can be used both for high-power diode lasers and for other lasers whose wavelengths can be transmitted by optical fibers. 2. Hand-held processing head for a high-power diode laser according to claim 1, characterized in that the protective glass carrier is composed essentially of the carrier ( 5 ) for the protective glass ( 3 ), a thermocouple ( 6 ) and a lock ( 4 ) that when the protective glass is inserted ( 3 ) direct contact between this and the thermocouple ( 6 ) is established, that the protective glass ( 3 ) is secured by means of the locking mechanism ( 4 ) and that the entire unit can be inserted or removed from the processing nozzle ( 13 ) by moving it or that a folding mechanism is provided for this. 3. Hand-held processing head for a high-power diode laser according to claims 1 and 2, characterized in that the carrier ( 5 ) for the protective glass ( 3 ) consists of a poorly heat-conducting material and thus thermal decoupling of the protective glass ( 3 ) from those caused by the machining process heated parts of the machining head is realized. 4. Hand-held processing head for a high-power diode laser according to claims 1 and 2, characterized in that the lock ( 4 ) is designed so that electrical contact to the thermocouple ( 6 ) is only made when there is a protective glass ( 3 ) in the carrier ( 5 ) and this is correctly inserted into the optical beam path. 5. Hand-held processing head for a high-power diode laser according to claim 1, characterized in that the speed power control includes a microcontroller ( 9 ) for signal processing, evaluation and generation, as well as a D / A converter ( 11 ) and an incremental encoder ( 12 ), The incremental encoder ( 12 ) has a displacement sensor ( 8 ), the microcontroller ( 9 ) has elements for communication ( 15 ) in the form of a programmable logic controller and those for laser release ( 16 ), laser safety ( 17 ) and for status and parameter display ( 18 ). and a power supply unit ( 19 ) is assigned to the D / A converter ( 11 ), and that there are active connections to the laser driver, to the laser source and to the processing nozzle ( 7 ). 6. Hand-held processing head for a high-power diode laser according to claim 1, characterized in that for realizing the speed additional wire feed control of the microcontroller ( 9 ) for the purpose of signal processing, evaluation and generation as well as the D / A converter ( 11 ) and the incremental encoder ( 12 ) is provided, the incremental encoder ( 12 ) the displacement sensor ( 8 ), the microcontroller ( 9 ) elements for communication ( 15 ) in the form of a programmable logic controller, elements for laser release ( 16 ), for laser safety ( 17 ) and for status and parameter display ( 18 ) and such additional wire enable ( 13 ) are assigned, while the D / A converter ( 11 ) is connected to an additional wire feed unit ( 14 ), and that there are active connections to the laser driver, the laser source and the processing nozzle ( 7 ). 7. Hand-held processing head for a high-power diode laser according to claims 1, 5 and 6, that the speed is set without motor-driven axes and that an optical or mechanical system is provided to record the speed is.   8. Hand-held processing head for a high-power diode laser according to claims 1 and 5, characterized in that the result of the signal processing in the microcontroller ( 9 ) is a control signal that describes the relationship between feed rate and laser power, the control signal being used to control the laser power and the Control takes place within a speed interval in which a change in the travel speed results in a change in the laser power. 9. Hand-held processing head for a high-power diode laser according to claims 1 and 6, characterized in that the result of the signal processing in the microcontroller ( 9 ) is a control signal which describes the relationship between the additional wire feed and the travel speed, the control signal of the control of the additional wire feed unit ( 14 ). , consisting of motor, wire guide system and wire supply, is used and the control takes place within a speed interval in which a change in the travel speed entails a change in the additional wire feed. 10. Hand-held processing head for a high-power diode laser according to claims 1, 5 and 6, characterized in that that the speed power control as well as the speed Additional wire feed control in other laser systems, for example with Solid-state lasers that are either hand-held or machine-guided are used can.