DE102011006532A1 - Device for welding axle carrier component of motor vehicle, has sensor arrangement that senses gap between components which are conveyed with clamping elements to welding position, and performs quality control of welded components - Google Patents

Abstract

The device has a sensor arrangement including cameras (6-8) and a control signal generating evaluation unit. The sensor arrangement is arranged in a starting position (5) with the components to be welded. The components in starting position, are held relative to one another by clamping elements (S). The joint gap between components is sensed by sensor arrangement. The components are conveyed together with clamping elements to welding position. The welded components are conveyed to starting position subsequently and quality control is performed by the sensor arrangement.

Description

The invention relates to a welding device, in particular for the automatic welding of axle support parts of motor vehicles according to the preamble of patent claim 1.

Such a welding apparatus is known from DE4326338C known. In this case, an automatic, sensitive real-time adaptation of all relevant welding parameters during the ongoing welding process and thereby a high welding quality is to be ensured by the component scanning limited to a few, the joint gap geometry including the joint gap measuring signals and converted into corresponding real-time welding process control commands. The visual inspection of the weld preferably takes place during the ongoing welding process with the aid of a video camera attached to the welding head.

The known method may be applicable to simple component geometries. In the case of complicated geometries, such as the mentioned axle carrier parts of motor vehicles, a real-time adjustment of welding process control commands is practically impossible because the necessary entrainment of the sensor device with the welding head fails because of space problems. Added to this is the mechanical / optical / thermal impairment of the arranged near the welding location sensor device

The object of the invention is to provide a welding device of the type mentioned in such a way that even under difficult welding conditions and especially for complicated component geometries high welding quality with low equipment and computing effort is achieved.

This object is achieved by the characterized in claim 1 welding device.

The invention has several special features.

On the one hand, the sensor arrangement has a dual function. It serves to detect the course and the cross-sectional geometry, in particular the gap width of the joint between the components to be welded. In addition, with their help, the quality control of the two components fixing weld seam is performed.

It is possible to simultaneously detect several joining gaps and to qualitatively evaluate the welds existing after the welding process. In this respect, the welding device according to the invention and the welding process carried out with its aid has a clear time advantage over, for example, a conventional laser triangulation method in which usually only the measurement of a joining gap or a weld is possible and several objects (gap / seam) are to be treated sequentially.

The two functions are performed outside the actual welding process. The scanning is done before, the quality control after the welding process.

Finally, the sensor arrangement is spatially separated from the actual welding site. As a result, mechanical / optical / thermal impairment of the sensor arrangement can be largely avoided.

In a particularly preferred embodiment of the invention according to claim 2, the components to be welded are scanned in a starting position by a plurality of cameras as part of the sensor arrangement. As a result, a spatial image of the observation location, here the individual pixels of the weld and thus a particularly meaningful information about the quality of the weld is obtained. This development of the invention for the quality control of an observation point is in principle from the US 7,324,712 known.

However, there is a significant improvement in the quality statement obtained with less computational effort when the actual camera image of the weld or the weld section is compared with corresponding target images. The image analysis methods used for this purpose are widespread.

Finally, a further improvement of the quality statement can be achieved with the means indicated in claim 4.

While hitherto the invention has been explained only with reference to a single weld seam, a clear improvement of the invention results when a plurality of cameras are used to observe a plurality of welds. As a rule, the cameras look at several weld seams and refer to the individual weld seams at different angles. Since they are stationary, the computational effort required for the target / actual image comparison is kept low, while at the same time high reliability of the quality statement.

The invention will be explained in more detail with reference to an embodiment in conjunction with the drawings. It shows in a highly schematic representation

1 a welding device according to the invention in a schematic representation,

2 to 7 the sequential steps of the operation in the execution of the method according to the invention.

The welding device shown in the figures is used for automatic welding of axle support parts 1 of a motor vehicle.

The welding device consists essentially of a handling robot 2 , two welding robots 3 and 4 as well as several cameras in an initial position 5 arranged and of which three cameras 6 . 7 and 8th are shown as representatives.

In the figures, clamping elements S are shown schematically, with which the individual components of the axle beam part 1 after insertion into a starting position 9 be rigidly fixed to each other in this starting position and which are effective throughout the workflow.

The handling robot 2 picks up the unit consisting of the components and the clamping elements S ( 2 ) and moves them into the field of vision 9 the cameras 6 . 7 and 8th , which at the same time the starting position 5 represents for the welding process. ( 3 ).

There, a 3-dimensional image of the components to be welded together and those on the welding robots 3 and 4 arranged welding torch (not shown) by means of an indicated burner robot control 10 adaptively adjusted ( 4 ) that with the welding torches in a welding position 11 applied welds (not shown) between the components of predetermined quality standards ( 5 ).

The finished axle carrier part 1 will return to the starting position 5 and thus into the field of vision of the cameras 6 . 7 and 8th brought ( 6 ).

There, in turn, the dimensional deviation of the multiple welds and the geometric seam quality is determined 3-dimensionally. For this purpose, the respective camera actual images are compared with corresponding target images and obtained by means of a known image comparison software, a quality statement for the various welds. The actual and target images are subjected to a gray image evaluation and a comparison of the gray values with the gray values of a reference weld.

At the same time, if the welding work is carried out properly, this fact is documented and recorded in an electronic memory (not shown).

The generally faultless axle carrier part is brought into an end position ( 7 ), which are identical to the starting position 9 is. There, the clamping elements S are removed and the axle carrier part 1 taken by an employee and possibly reworked before they are passed on to the next processing station.

If one of the welds is not correct, the component is ejected with a corresponding error information and subjected to reworking. If the welds are correct, the next regular processing step is performed.

In particular, axisymmetric parts, such as a front axle can also from the two welding robots 3 and 4 be welded at the same time. The first robot welds 3 as master the components of the left, the second robot 4 as slave, the right side. For each weld (independent left or right) optimal welding process parameters are used. A pre-detected (too) large gap will be compensated by adjusting the welding speed, voltage and current as well as wire feed. The parallel welding robots 3 and 4 are controlled independently of each other.

Each weld is welded independently of all other, even symmetrically arranged welds with optimal welding parameters (welding speed, voltage and current, as well as wire feed). The optimum welding parameters and welding torch travel distances are in the burner robot control program 10 deposited. If, for example, the welding speed is different, predetermined symmetrical synchronization points in the trajectory of the two robots can be used 3 and 4 in which the faster robot waits for the other, a synchronization of the two robots can be achieved again.

After the welding process, every seam is passed through the cameras 6 . 7 and 8th individually tested. The test procedure for all welds runs simultaneously.

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 4326338 C [0002]
• US 7324712 [0011]

Claims (4)

Welding device, in particular for the automatic welding of axle support parts of motor vehicles, having a the course and the cross sectional geometry, in particular the gap width of the joint gap between the components to be welded scanning sensor arrangement including a Stellsignaler generating evaluation, as well as with a signal-controlled, the welding parameters (welding speed, welding power and / or Weld seam positioning) variable adjusting and the welding head multiaxially adjustable the joining gap course tracking adjusting device, characterized in that the sensor arrangement ( 6 . 7 . 8th ) stationary and in a starting position ( 5 ) is aligned with the components to be welded, that the components are held in this initial position by Aufspannelemente (S) relative to each other and their joint gap is scanned by the sensor assembly that the components then spent together with the clamping elements in the welding position and provided there with welds then, that the welded components are in the starting position ( 5 ) and then quality control is performed by the sensor assembly. Welding device according to claim 1, characterized in that the components to be welded in a starting position ( 5 ) by several cameras ( 6 . 7 . 8th ) are sampled as part of the sensor array. Welding device according to claim 2, characterized in that the quality control is obtained by comparing a camera image with a target image. Welding device according to claim 2 or 3, characterized in that the quality control is carried out by means of a gray image evaluation and comparison of the gray values with the gray values of a reference weld.

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