DE102009041933A1 - Method for laser welding of components by a robot, comprises pre-determining a weldseam-reference profile and moving a component to be welded and a laser beam relative to each other - Google Patents

Abstract

The method for laser welding of components (3.1, 3.2) by a robot (1), comprises pre-determining a weldseam-reference profile and moving a component to be welded and a laser beam (4) relative to each other. A base movement of the component to be welded and the laser beam relative to each other corresponding to the weldseam-reference profile is superimposed to a compensation movement in order to compensate tolerances. The compensation movement of the component is transverse to the base movement. The compensation movement is carried out in different plain. The method for laser welding of components (3.1, 3.2) by a robot (1), comprises pre-determining a weldseam-reference profile and moving a component to be welded and a laser beam (4) relative to each other. A base movement of the component to be welded and the laser beam relative to each other corresponding to the weldseam-reference profile is superimposed to a compensation movement in order to compensate tolerances. The compensation movement of the component is transverse to the base movement. The compensation movement is carried out in different plain inclined against the weldseam-reference profile and is periodic movement. The compensation movement is repeating or cyclic pendulum movement around the weldseam-reference profile and is pre-defined on the basis of tolerances to be compensated. The tolerances to be compensated comprise geometric tolerances of the component, position- and/or orientation tolerances of the component to be welded and/or position- and/or orientation tolerances between the component and the laser beam. The component to be welded is moved by grip clamping technology through the robot relative to a laser head (2) for emitting the laser beam, or the laser head is moved through the robot relative to the component to be welded. The laser beam is moved optically relative to the laser head. Independent claims are included for (1) a control device for a robot; and (2) a computer program.

Description

The present invention relates to a method and an apparatus for the laser welding of components by means of a manipulator, in particular a robot, wherein a desired weld seam predetermined and a component to be welded and a laser beam are moved relative to each other.

For example, from the EP 1 018 393 B1 and the DE 20 2004 003 775 U1 It is known to move a laser head for laser welding by means of an industrial robot relative to a component to be welded.

However, laser welding places very high demands both on the manufacturing and positioning accuracy of the components to be welded as well as the position and orientation of the laser beam relative to the components. In part, the permissible tolerances are in the range of 1/100 mm to 1/10 mm.

The DE 37 33 568 A1 proposes therefore, to be welded together components in their desired positions each other partially overlapping, fix and press against each other. However, only tolerances of the component dimensions and clamping positions can be reduced. In order to compensate for absolute and Wiederholungs inaccuracies of the robot and thus tolerances of the laser beam relative to the components, a complex measurement and control technology is required, which detects the position and orientation of the laser head relative to the component and corrected so that a focal spot a predetermined weld -Sollverlauf leaves. This is currently opposed to a greater use of robot-assisted laser welding systems.

Object of the present invention is therefore to improve the laser welding by means of a manipulator.

This object is achieved by a method having the features of claim 1. Claim 12, a control device, claim 13 or 14, a computer program or a computer program product, in particular a storage medium or a data carrier, for performing a method according to claim 1 under protection. The subclaims relate to advantageous developments.

According to a method according to the invention for the laser welding of components, for example metal sheets, by means of a manipulator, preferably one, in particular multi-axis, industrial robot such as an articulated robot, a predetermined weld line profile is predetermined, which may be at least partially rectilinear, but also curved. The manipulator then performs a movement of the component to be welded and of the laser beam relative to one another.

For this purpose, on the one hand, a component to be welded, in particular by means of gripper clamping technique, can be moved by the manipulator relative to a preferably stationary laser head, which emits the laser beam. On the other hand, the laser head can be moved by the manipulator relative to the, preferably fixed, component to be welded. Component and laser head can also be moved by a respective manipulator relative to each other.

Additionally or alternatively, the laser beam can be moved relative to the laser head emitting it by a beam guiding device. This can be done in particular optically, for example by means of movable deflecting mirrors, optical fibers such as glass fiber cables, adjustable diaphragms and / or variable lenses. In this respect, in particular a focusing of the laser beam, i. e. a change in the distance of its focal spot relative to the laser head, referred to as a movement of the laser beam relative to the laser head emitting it.

According to the invention, a basic movement of the component to be welded and of the laser beam relative to one another, which is directed in the seam or welding direction of the desired weld line, is superimposed on a compensating movement in order to compensate for tolerances. This compensation movement can advance, for example, by appropriate change in the desired weld line before its departure, or during the implementation of the basic movement, i. e. the departure of the unchanged or not tolerance-compensated weld setpoint course with the focal spot of the laser beam. The ground and their superimposed compensation movement together, the movement of the component to be welded and the laser beam relative to each other, in particular a track of a focal spot on the component.

Basic and compensatory movement can be carried out, in each case at least partially, by the same or by different actuators.

For example, the manipulator can move the component (or the laser head) in accordance with the basic movement, that is to say past the laser head (or the component) so that the focal spot would exit the desired weld profile. In this case, the manipulator can additionally perform the compensation movement, so that the focal spot deviates at least in sections from the non-tolerance-compensated weld desired course. In this case, basic and Compensation movement completely by the same actuator, ie running the manipulator.

Likewise, during the movement of the component (or of the laser head) through the manipulator, the laser beam can additionally be moved by the beam guiding device relative to the laser head. In this case, for example, the manipulator, the basic movement and the Strahlleiteinrichtung the compensation movement or the Strahlleiteinrichtung the basic movement and the manipulator perform the compensation movement. In this case, basic and compensation movement are each completely by different actuators, i. e. the manipulator on the one hand and the Strahlleiteinrichtung on the other hand executed.

Basic and / or compensating movement of the component and the laser beam relative to one another can also be carried out jointly by the manipulator and the beam guiding device, in that the coordinated movements of the manipulator and the beam guiding device together result in the basic or compensation movement. In this case, basic or compensation movement by different actuators each partially, i. e. executed in part by the manipulator and partly by the Strahlleiteinrichtung.

In a preferred embodiment, the compensating movement, in sections or over the entire desired weld path, has a component transverse to the basic movement or the desired weld path, which is preferably alternately in the opposite direction. In particular, a pendulum movement can be superimposed transversely to the non-tolerance-compensated weld seam course. As a result, the region of the component covered by the weld seam is broadened transversely to the initially predetermined weld seam course and can thus compensate for tolerances or bridge gaps.

The compensation movement can also have components that are directed counter to the basic movement. In particular, in conjunction with alternately opposing components transverse to the basic movement can thus circles, spirals, loops, eights or other open or closed curves along the initially predetermined weld line profile generated and thus compensated for tolerances or gaps are bridged.

In particular, with mutually inclined surfaces of components to be welded together, the compensation movement in different, in particular against each other inclined to the desired weld plane, planes are executed and done, for example, as so-called corner pendulum.

In a preferred embodiment, the compensating movement is a periodic movement in sections or over the entire desired weld path. In this case, a periodic movement is understood in particular to mean a movement which has a plurality of identical sections offset from one another by a period, pendulum or wavelength, for example a repeated sawtooth, trapezoidal, sinusoidal or achter movement along the setpoint weld path. The distance of the maximum deflections is referred to as pendulum width.

Preferably, the compensation movement is predetermined on the basis of compensating tolerances. For example, a pendulum shape (sawtooth, trapezoidal, spiral, aft or the like), width and / or period can be specified based on the tolerances to be compensated. For example, to compensate for larger tolerances, the pendulum width can be increased, a spiral instead of a trapezoidal pattern can be selected, or the period length of a figure-eight-shaped pendulum motion can be reduced.

Additionally or alternatively, the compensation movement may also comprise a constant or variable offset from the basic movement. For example, to compensate for a tolerance which exists only or for the most part in an excellent direction, such as an oversize, the superimposed basic and compensation movement in this direction may be offset from the basic movement, or it may be a pendulum about a parallel to the weld Sollverlauf staggered line done.

With a method according to the invention can preferably geometry tolerances of the component, i. e. Deviations from a desired shape or dimension, position and / or orientation tolerances between components to be welded relative to each other, such as inaccurately clamped components, or position and / or orientation tolerances between the component and the laser beam, for example due to an absolute or Repeat error of the manipulator, to be compensated.

The present invention is particularly advantageous in pure or sole laser welding, i. e. without simultaneous combination with other welding processes such as gas melting, arc, inert gas or resistance welding.

Further advantages and features emerge from the subclaims and the exemplary embodiments. This shows, partially schematized:

1 : a robot during laser welding according to a method of the invention;

2A : a top view of the in 1 indicated by a dashed circle area in a welding according to the prior art;

2 B : the welding of two components according to a method according to the invention in one 2A corresponding view;

2C : a modification of the weld in 2 B ;

3A : the welding of two components according to the prior art in one 2A corresponding top view;

3B : the welding of two components according to a method according to the invention in one 2 B corresponding view; and

4A , B: various forms of seams that can be produced by a method according to the invention.

1 shows a six-axis articulated robot 1 with a gripper clamping device 1.1 , their jaws 1.10 to 1.13 Sheet metal parts to be welded together 3.1 . 3.2 fix a V2A sheet metal frame. In the enlarged plan view of 2A is the overlapping arrangement of the components 3.1 . 3.2 to recognize which by means of melting along a U-shaped weld desired course 10 (dash-dotted in 2A ) are to be connected to each other by laser welding.

The robot leads to this 1 the components clamped in gripper clamping technology 3.1 . 3.2 so on a fixed laser head 2 passing a laser beam emitted by this 4 or its in 2A indicated as a crosshair focal spot on the components 3.1 . 3.2 forms the desired weld.

In 2A a target configuration is shown in broken lines, based on which the weld setpoint course is drawn 10 and thus a basic movement of the robot 1 or its tension gripper 1.1 relative to the fixed laser head 2 planned, for example, programmed offline or taught online.

In the example greatly simplified and exaggerated example illustrated has a lower frame part 3.1 compared to its desired configuration on a manufacturing or Aufspannbedingedte deviation Δy_BT. Due to a positioning inaccuracy of the robot 1 are also the tension gripper 1.1 and thus the components fixed on it 3.1 . 3.2 offset from the target configuration by Δx_IR.

Now according to the state of the art, the robot 1 only the basic movement corresponding to the non-tolerance-compensated weld seam course 10 from, the focal spot, which is aligned with the target configuration shown in dashed lines, creates a weld 50 that, as in 2A recognizable, for the most part outside of the component to be welded 3.1 lies. This can only be complicated by metrological detection of the deviation of in 2A pulled out shown actual configuration compared to the desired configuration and corresponding readjustment of the robot movement to eliminate the deviation Δx_IR and improved clamping to eliminate the deviation Δy_BT be met.

According to the in 2 B shown embodiment of the present invention, the positional tolerance .DELTA.Y_BT of the components to be welded 3.1 . 3.2 relative to each other and the positional tolerance Δx_IR between the components and the laser beam 4 compensated, without requiring a complex measurement and control technology to reduce the positioning inaccuracy of the robot 1 and the Aufspannbedingten deviation is required.

For this purpose, according to a method according to the invention, which in an in 1 for simplification in the base of the robot 1 indicated control device 1.2 expires, the above-explained basic movement of the robot 1 , which is the departure of the setpoint desired configuration for the desired configuration 10 corresponds, a compensation movement superimposed. The robot leads to this 1 with his tension gripper 1.1 in addition to the basic movement, a pendulum movement transverse to the weld desired course 10 from how they are in 2 B is drawn.

It can be seen that now the components 3.1 . 3.2 along all three sides of the U-shaped weld desired course 10 at least partially welded through and thus joined together. The in 2 B drawn pendulum length PL and / or pendulum width PB of the weld resulting from the basic and compensation movement 5 can be specified according to the tolerances Δy_BT, Δx_IR to be compensated.

In a modification, not shown, the center line of the pendulum movement to the interior of the U-shaped weld desired course 10 be postponed. In a further modification, the opposing deviations can transversely to the weld desired course 10 be chosen differently big. In particular, instead of a symmetrical about the weld-desired course 10 changing oscillating motion are performed a swelling pendulum movement, which differs from the weld desired course 10 proceeding only to the interior of the U-shaped weld desired course 10 extends as in 2C is indicated.

3A . 3B show a modification of the above with reference to 2A . 2 B explained method, wherein the sheets 3.1 . 3.2 not by a continuous, but by a broken weld 5 respectively. 50 be connected in the form of individual welding points. While in the prior art ( 3A ) the welding points 50 during the basic movement of the robot 1 along the weld setpoint course 10 be set so that 2/3 of the welds are sheet metal 3.1 do not weld through, connect according to the method of the invention, half of the welds 5 the components 3.1 and 3.2 ,

4A shows the weld 5 characterized by a periodic compensatory motion in spiral form with components transverse (up / down in 4A ) and counter (from right to left in 4A ) of a basic movement (from left to right in 4A ) along the weld setpoint course 10 results.

4B shows a weld, as they are by corner pendulum trapezoidal shape in two different, against each other to the desired weld line 10 inclined planes with angularly arranged components 3.1 . 3.2 results.

LIST OF REFERENCE NUMBERS

1

robot

1.1

clamping gripper

1.2

control device

1:10 to 1:13

jaws

2

laser head

3.1, 3.2

component

4

laser beam

5

Weld

10

Weld desired course

50

Weld

Δx_IR

Positioning deviation of the robot

Δy_BT

Positioning deviation of the component

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1018393 B1 [0002]
• DE 202004003775 U1 [0002]
• DE 3733568 A1 [0004]

Claims (14)

Method for laser welding of components ( 3.1 . 3.2 ) by means of a manipulator, in particular a robot ( 1 ), wherein a weld desired course ( 10 ) and a component to be welded ( 3.1 . 3.2 ) and a laser beam ( 4 ) are moved relative to each other; characterized in that a basic movement of the component to be welded and of the laser beam relative to each other according to the desired weld seam course ( 10 ) is superimposed on a compensation movement to compensate for tolerances. A method according to claim 1, characterized in that the compensation movement has at least partially a component transverse to the basic movement. Method according to one of the preceding claims, characterized in that the compensating movement has at least in sections one of the basic movement opposing component. Method according to one of the preceding claims, characterized in that the compensating movement takes place at least in sections in different, in particular inclined relative to each other around the weld seam course, planes. Method according to one of the preceding claims, characterized in that the compensation movement is at least partially a periodic movement (PL). A method according to claim 5, characterized in that the compensating movement at least partially an alternating ( 2 B ) or swelling ( 2C ) Is pendulum motion around the desired weld line or a reference line offset therefrom. Method according to one of the preceding claims, characterized in that the compensation movement is predetermined on the basis of compensating tolerances (Δx_IR, Δy_BT). Method according to one of the preceding claims, characterized in that the tolerances to be compensated geometry tolerances of the component, positional and / or orientation tolerances (Δy_BT) to be welded components relative to each other and / or position and / or orientation tolerances (Δx_IR) between the component and the Include laser beam. Method according to one of the preceding claims, characterized in that a component to be welded ( 3.1 . 3.2 ), in particular by means of gripper clamping technology ( 1.1 . 1.11 - 1.13 ), by the manipulator relative to a laser head ( 2 ) for emitting the laser beam ( 4 ) is moved. Method according to one of the preceding claims, characterized in that a laser head for emitting the laser beam is moved by the manipulator relative to the component to be welded. Method according to one of the preceding claims, characterized in that the laser beam, in particular optically, is moved relative to a laser head emitting it. Control device ( 1.2 ) for a manipulator, in particular a robot ( 1 ), which is set up to carry out a method according to one of the preceding claims. A computer program that carries out a method according to one of claims 1 to 11 when used in a control device ( 1.2 ) according to claim 12 expires. A computer program product with program code stored on a machine readable medium and comprising a computer program according to claim 13.

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