DE102018104475A1 - Method for welding components - Google Patents

Abstract

Method for welding components with the following steps:
a) The components to be welded P1, P2 are gripped by handling robots 2, 3, 12, 13 and positioned relative to at least one optical sensor 5, 6;
b) The optical sensor detects the geometry of the components and their position;
c) The detected geometry is compared in an evaluation unit with a CAD model of the components P1, P2 in order to determine a correction value for positional correction from any deviations from the CAD model;
d) The handling robots correct in a first control loop the relative position as a function of the correction value by repeating steps b) to d) until the desired relative position is reached;
e) The position-corrected components P1, P2 are displaced by the handling robots in a welding position and welded together in the welding position by means of at least one welding robot 4, 14.
f) The welded components (P1, P2) are measured again after welding using at least one optical sensor to detect any deviations of an actual value of the position of a target value to determine from the control difference between the actual value and target value, a control value the first control loop for position correction of subsequent components to be welded is supplied.

Description

The invention relates to a method for welding components according to the features of patent claim 1.

The DE 10 2004 049 332 A1 discloses a method for automated positioning of at least two components by means of a plurality of industrial robots, wherein a first positioning robot positions a first component in a first joining position and a second positioning robot positions a second component in a second joining position. During the positioning of the second component, the at least temporarily varying distance of the second component to the first component is determined by means of a sensor unit and by means of a control unit, which is connected to the sensor unit and at least one positioning robot or a joint positioning of the components to each other in a respective joining position carried out. The positioning is regulated.

The DE 10 2015 107 859 A1 discloses a mounting system using robots and using means for optically detecting the location of two components to be interconnected. A controller operatively connected to the vision system and the robotic system serves to control the robotic system to position the second component relative to the first component based on the locations previously determined by the vision system.

The DE 10 2011 006 532 A1 describes a welding system for device-free welding. The system has at least one handling robot, a welding robot and three cameras, wherein the cameras generate a 3-dimensional image of the component to be welded. The components to be welded are positioned on a complex clamping unit.

The WO 2007/004983 A1 discloses a method of welding components whereby the movement of the handling robots carrying the components is continuously monitored and optionally corrected.

Proceeding from this, the object of the invention is to provide a method for the automatic welding of components within a robot cell, which can be quickly converted to different components and does not require a jig.

This object is achieved by a method having the features of patent claim 1.

The subclaims relate to advantageous developments of the invention.

1. a) Die zu verschweißenden Bauteile werden von Handhabungsrobotern gegriffen und relativ zu mindestens einem optischen Sensor positioniert;
2. b) Der optische Sensor erfasst die Geometrie der Bauteile und deren Lage;
3. c) Die erfasste Geometrie wird in einer Auswerteeinheit mit einem CAD-Modell der Bauteile verglichen, um aus etwaigen Abweichungen zu dem CAD-Modell einen Korrekturwert zur Lagekorrektur zu bestimmen;
4. d) Die Handhabungsroboter korrigieren in einem ersten Regelkreis die relative Lage in Abhängigkeit von dem Korrekturwert unter Wiederholung der Schritte b) bis d) bis die gewünschte relative Lage erreicht ist;
5. e) Die lagekorrigierten Bauteile werden von den Handhabungsrobotern in eine Schweißposition verlagert und in der Schweißposition mittels wenigstens eines Schweißroboters miteinander verschweißt;
6. f) Die verschweißten Bauteile werden nach dem Verschweißen unter Verwendung wenigstens eines optischen Sensor erneut vermessen um etwaige Abweichungen eines Istwertes von einem Sollwert zu erfassen, um aus der Regeldifferenz zwischen Istwert und Sollwert einen Steuerwert zu bestimmen, der dem ersten Regelkreis zur Lagekorrektur nachfolgender zu verschweißender Bauteile zugeführt wird.

The inventive method for the automatic welding of components provides the following steps:

1. a) The components to be welded are gripped by handling robots and positioned relative to at least one optical sensor;
2. b) The optical sensor detects the geometry of the components and their position;
3. c) The detected geometry is compared in an evaluation unit with a CAD model of the components in order to determine a correction value for positional correction from any deviations from the CAD model;
4. d) The handling robots correct in a first control loop the relative position as a function of the correction value by repeating steps b) to d) until the desired relative position is reached;
5. e) The position-corrected components are displaced by the handling robots in a welding position and welded together in the welding position by means of at least one welding robot;
6. f) The welded components are measured again after welding using at least one optical sensor to detect any deviations of an actual value of a target value to determine from the control difference between the actual value and setpoint a control value to be welded to the first control loop for position correction subsequently Components is supplied.

The sensor used is preferably a triangulation sensor. The position of the components detected by the sensor is compared with a CAD model or with production data and, if necessary, the position of the components is corrected after comparison with the CAD model or with the production data.

As soon as the two components are aligned correctly with one another, ie the desired welding gap width is set, the components are moved to a welding robot or they are aligned directly in front of the welding robot. Subsequently, the correctly positioned components are welded together.

To check the result, the two welded components are measured again. The result of this measurement is converted into a control value. This control value is supplied to the first control loop for positioning further components to be joined together.

The invention assumes that a larger number of components are to be welded in series production. The repetitive manufacturing steps allow the system to take into account control differences in the first control loop during subsequent identical production steps in order to optimize positional corrections on the components which have not yet been welded. The method thus provides production parameters for the follow-up order and represents an active control loop for quality improvement.

From the optical measurement during the quality control can also draw conclusions about the welding parameters such as wire feed, welding speed, welding path and current, but in particular draw conclusions on whether the welding gap width was selected and set correctly.

The welded components can be measured with the optical sensor of the first control loop. In this case, they are preferably positioned by one of the two handling robots after welding again relative to the at least one optical sensor. There is a quality control e.g. with regard to the weld seam position, the tolerances to be maintained and with regard to the distortion of the component, of course, in order to detect the alignment of the component. Since the two components are connected to each other, the handling is sufficient by a single handling robot.

The welded components can therefore be checked in the station where they have been welded. The quality control can also be done outside the welding chamber or welding station. The quality control can be done with multiple sensors to optimize the quality of the weld

If the first handling robot hands over the components welded together for quality control, the second handling robot can add another component ( 3 , Component), which is to be connected to at least one of the already welded components. For this purpose, the components to be welded can in turn be positioned relative to the at least one optical sensor to detect the position of the components and to correct them if necessary, so that the components to be welded in the next step by means of at least one welding robot welded together. This procedure is repeated until the weld assembly is completed. Also in this development of the method with three or more components, the first control process for positioning the component is influenced by results of the automated optical quality control.

The optical sensor may be mounted stationary in a first embodiment. Alternatively, the sensor can be moved in one or more axes. The sensor can be arranged, for example, on a portal and moved to measure in the horizontal direction. It is also conceivable that the sensor is moved only in the Z-direction, that is in the vertical direction, to bring him only to measure in a suitable measuring position. After the measuring process, the sensor can be returned to its original position. As a result, there are fewer obstacles within the movement space of a handling robot, which should be considered during handling of the component. A movable optical sensor can be moved to detect the position of the components relative to the components. Alternatively, the components may be moved relative to the at least one sensor during detection of the location of the components. That is, the sensor can be guided past the component, or the component is guided past the sensor. In principle, it is also possible to combine both types of movement, namely those of the sensor and those of the components.

The sensors for checking the position of the components and for quality control can be mounted spatially in front of or next to the welding robot.

To check the welding gap, the welding robot may also have an optical sensor that controls the welding gap before the parts are joined together. This is a different optical sensor than the fixed optical sensor. Should the welding gap be out of tolerance, the handling robots will adjust the orientation of the parts. The sensor on the welding robot moves to a rest position after successful measurement of the welding gap.

The control unit generating evaluation unit can be connected in an advantageous embodiment of the invention with the welding robot to correct the path control of the welding robot, if necessary. Other welding parameters, such as the delivery of the welding wire can be controlled depending on the actual measured welding gap width and position of the welding gap. The adaptation of the welding robot with respect to its path control and further welding parameters is adaptive as a function of the individual measurement result of the respective components. In an advantageous manner Further development of the invention, a total of four handling robots and two welding robots can be integrated into a welding cell and can share at least one fixed optical sensor for checking the position of the components and for quality control. Preferably, the welding robots are arranged opposite one another. As a result, different components can be produced simultaneously and the throughput of the system can be increased. An essential advantage of device-free welding of components is that the handling robots can position the components to be welded in the ideal well position, ie that the melt generated during welding flows by gravity to the lowest point between the components. As a result, the welding quality and the strength of the welds can be significantly increased, in contrast to traditional clamping devices, in which the parts are rigidly fixed. The handling robots move the components to be welded freely in the room.

• 1 Eine Draufsicht auf eine erste Ausführungsform einer Schweißzelle zur Durchführung des erfindungsgemäßen Verfahrens;
• 2 eine Draufsicht auf eine zweite Ausführungsform einer Schweißzelle zur Durchführung des erfindungsgemäßen Verfahrens und
• 3 eine Draufsicht auf eine weitere Ausführungsform einer Schweißzelle zur Durchführung des erfindungsgemäßen Verfahrens.

The invention will be explained in more detail with reference to the embodiments illustrated in the drawings. Show it:

• 1 A plan view of a first embodiment of a welding cell for carrying out the method according to the invention;
• 2 a plan view of a second embodiment of a welding cell for performing the method according to the invention and
• 3 a plan view of another embodiment of a welding cell for carrying out the method according to the invention.

The basic sequence of the method according to the invention for connecting two components, as P1 and P2 in the first step, that includes a component P1 is gripped by a handling robot. The component P1 is guided by the handling robot in a second step to a sensor. In the third step, the component to be connected is scanned. In the fourth step, a correction vector or the rotation of the component is calculated. In the fifth step, the component comes from one side P1 positioned. Coming from the other side is the second component P2 fed. Also, this component has been measured and positioned according to the aforementioned steps. This creates a virtual welding gap in the sixth step. The positioning is regulated.

Now, the two so positioned components are transferred to a welding robot or they have already been positioned directly in front of him. The welding robot performs the welding process. Finally, a quality inspection takes place. Optional is after the correct positioning of the components P1 and P2 For the welding position another check step possible by initiating a separate welding gap measurement and by an optical sensor again the position of the welding gap is checked. Depending on the measurement result, the welding program can then be corrected.

This basic procedure can be used for other components P3 . P4 , ... are repeated, with the welded together components P1 . P2 to be welded in the next step.

1 shows in a view from above a welding cell 1 with two handling robots 2 . 3 as well as a welding robot 4 , In addition, there are first moving sensors 5 . 6 on a portal 17 as well as another movable sensor 7 at the welding robot 4 , The first two sensors 5 . 6 are linear along the portal 17 traversable. Inside the welding cell 1 There are three tables 8th . 9 . 10 , The first handling robot 2 assigned table 8th serves to accommodate the main part or first component with which all other components are to be welded. The component is with P1 designated.

At the second table 9 which is the second handling robot 3 is assigned, there are items, one of which as an example P2 is designated. The second handling robot 3 picks up these individual components P2 to attach it to the first component P1 to position. For this purpose, the components P1 . P2 along the sensors 5 . 6 guided, then put in the right position where a sensor 7 at the welding robot 4 once again checked the position of the welding gap. The finished, welded component is then placed on the third table 10 stored.

The welding cell 1 the 2 has substantially the same components as in the 1 on, however, is the welding robot 4 in this embodiment, in the image plane above. The stationary sensors 5 . 6 are no longer in the middle of the welding cell 1 , in a sense between the handling robots 2 . 3 but next to the welding robot 4 ,

The drawn circles clarify the range of motion of the individual handling robots 2 . 3 and also the welding robot 4 , It can be seen that the arrangement of stationary sensors 5 . 6 next to the welding robot 4 offers the possibility of handling robots 2 . 3 moving components P1 . P2 at a short distance to the welding robot 4 to measure and then before the welding robot 4 in the correct position.

3 shows a welding cell with four handling robots 2 . 3 . 12 . 13 and two welding robots 4 . 14 , Two handling robots each 3 . 12 or. 2 . 13 share a vertically movable sensor 5 . 6 , As with the previous embodiments, another movable sensor 7 each at the welding robots 4 . 14 arranged. It can be seen from the overlap of the marked movement circles which handling robots interact with which welding robot. The handling robots 12 . 13 work with the welding robot 14 together and the handling robots 2 . 3 in the upper half work with the welding robot 4 together. The special feature is that the component P1 , Which via a feed to the lower in the image plane, the first handling robot 12 is different, that in the upper half of the picture, that is in the other half of the welding cell 11 will be produced. For example, bumpers are produced by welding in the lower half of the picture, while torsion beam axles are produced in the upper half of the picture. The respective production sequence is based on the 1 to 3 already explained. The special feature of the embodiment of 4 is that within a single, shared welding cell 11 at the same time two different components or groups of components are processed, wherein the robot groups are the fixed sensors 5 . 6 share, ie share. In 4 is shown in the image plane on the left, that further handling robot 15 . 16 are provided, which for equipping the welding cell 1 are provided with components.

The inventive method is highly flexible. The embodiment of 3 shows that one and the same sensor can measure different components within a measuring cell, as well as essentially identical handling robots can access different components. The invention thus also covers the possibility of quickly changing the production. If there is a greater need for twist beam axles, both robots can quickly be converted to the production of torsion beam axles until the demand is met. It can be processed immediately consecutive different welding jobs. Unlike in 3 presented, the orders can be quite mixed. The handling robots and the sensors used, including the welding robots, are capable of directly producing another welding assembly without much retooling, so that there is no interruption in the production cycle or long downtimes of the handling robots and the welding cell as a whole.

LIST OF REFERENCE NUMBERS

1 -

welding cell

2 -

handling robots

3 -

handling robots

4 -

welding robots

5 -

sensor

6 -

sensor

7 -

sensor

8th -

table

9 -

table

10-

table

11 -

welding cell

12 -

handling robots

13 -

handling robots

14 -

welding robots

15 -

handling robots

16 -

handling robots

17 -

portal

P1 -

component

P2 -

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

• DE 102004049332 A1 [0002]
• DE 102015107859 A1 [0003]
• DE 102011006532 A1 [0004]
• WO 2007/004983 A1 [0005]

Claims (8)

Method for welding components with the following steps: a) The components to be welded (P1, P2) are gripped by handling robots (2, 3, 12, 13) and positioned relative to at least one optical sensor (5, 6); b) The optical sensor detects the geometry of the components and their position; c) The detected geometry is compared in an evaluation unit with a CAD model of the components (P1, P2) in order to determine a correction value for positional correction from any deviations from the CAD model; d) The handling robots correct in a first control loop the relative position as a function of the correction value by repeating steps b) to d) until the desired relative position is reached; e) The position-corrected components (P1, P2) are moved by the handling robots in a welding position and welded together in the welding position by means of at least one welding robot (4, 14); f) The welded components (P1, P2) are measured again after welding using at least one optical sensor to detect any deviations of an actual value of the position of a target value to determine from the control difference between the actual value and target value, a control value the first control loop for position correction of subsequent components to be welded is supplied. Method according to Claim 1 , characterized in that after the welding operation of one of the two handling robots (2, 3, 12, 13) the two components welded together (P1, P2) for quality control again relative to the at least one optical sensor (5, 6) positioned. Method according to Claim 1 or 2 , characterized in that the at least one sensor (5, 6) for detecting the position of the components (P1, P2) is moved relative to the components (P1, P2) and / or the components (P1, P2) during the detection of the Location of the components (P1, P2) relative to the at least one sensor (5, 6) are moved. Method according to one of Claims 1 to 3 , characterized in that for checking a welding gap, an optical sensor (7) on the welding robot (4, 14) is arranged, which controls the welding gap before the components (P1, P2) are welded together, said optical sensor (7) connected to the correction value generating evaluation unit to correct after detecting the relative position of the components to be welded (P1, P2) to each other, their position, if necessary. Method according to Claim 4 , characterized in that the optical sensor (7) on the welding robot (4, 14) moves after checking the welding gap in a rest position. Method according to one of Claims 1 to 5 , characterized in that the control signals generating evaluation unit is connected to the welding robot (4, 14) to correct the path control of the welding robot, if necessary. Method according to one of Claims 1 to 6 , characterized in that four handling robots (2, 3, 12, 13) and two welding robots (4, 14) are integrated into a welding cell (11) and at least one fixed optical sensor (5, 6) for checking the position of Sharing components and for quality control. Method according to one of Claims 1 to 7 , characterized in that the handling robots (2, 3, 12, 13) position the components to be welded (P1, P2) so that the melt flows by gravity to the lowest point between the components (P1, P2).

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