Electric heating – Metal heating – By arc
Patent
1997-06-11
1999-05-11
Mills, Gregory
Electric heating
Metal heating
By arc
21912164, 21912184, B23K26/14
Patent
active
059024976
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention refers to a process for the cooling of a welding seam area during laser welding of plates or strips, particularly for use in car body construction by the directed infeed of a liquid cooling agent.
BACKGROUND OF THE INVENTION
Moreover, the invention relates to an apparatus required for the implementation of this process. During the laser welding of plates and strips that, for example, are used in car body construction, the quality of the welding seam is of great significance. During butt welding the width of the gap is instrumental in assuring the quality of the weld. If the gap is too wide, the laser beam "falls through" or the weld quality deteriorates to an extent that scrap is produced. Due to the high volume of energy applied at the laser beam focus there is a risk that as a result of thermal expansion in the plate this applied energy causes a gap ahead of the focal point that severely impedes the quality of the welding seam. For that reason, cooling of the welding seam area is of great importance since an effective cooling will prevent gap formation.
During laser welding a cooling action by ambient air is well known as is the injection of cooling air through nozzles or the infeed of gases such as helium or argon. Furthermore, cooling methods involving clamping jaws or copper ledges have also been employed. For example, cooling a weld area with gaseous media during laser welding is known as prior art from EP 0 450 349.
The processes covered by prior art are partly unsatisfactory as far as their cooling performance is concerned, to some extent they require substantial expenditure for equipment. When the cooling process involves gases considerable gas volumes have to be blown onto the welding seam to obtain results that can viewed as fairly, if at all acceptable. If cooling of the weld seam area is to be effected by means of clamping jaws, e.g. for copper ledges (EP 01 89 806), these have to be carefully controlled and arranged. Moreover, cooling by clamping jaws is not feasible in the event of continuous welding processes.
From DE 40 10 077 a process is known for the continuous welding of abutting strips (plates) by means of a laser beam without adding filler metal. This process provides for the strips to be cooled in the area of the welding seam immediately after the welding focus so that the cooling intensity is controlled as a function of the width of the gap formed directly before the welding focus by the abutting edges of the strip in strip running direction in such a manner that this gap width remains within a tolerance range. From this process it is also known that cooling can be effected on both sides of the strip. For cooling, a gaseous medium is proposed, preferably air. To get as close as possible to the welding focus the narrow tip of the injection nozzles is envisaged to project into the gap between the clamping rollers. The blowing direction of the injected gaseous medium is away from the welding focus. Controlling the cooling intensity of the injected gaseous medium is achieved by way of its flow rate. In connection with this process an apparatus for the continuous welding of abutting strips (plates) by means of a stationary welding beam acting on the abutting strip edges is proposed that includes clamping rollers arranged in pairs vertically to the running strip direction at both sides of the strips to be welded, said clamping rollers forming a gap in the area of the joint of the strip through which the stationary laser beam hits the abutting edges to be welded. For this purpose a control apparatus is employed that has a measuring unit located in the direction of strip travel immediately ahead of the welding focus monitoring, as actual value, the width of the gap formed by the abutting strip edges and a cooling unit arranged in the direction of strip travel behind the welding focus and acting on the strips in the area of the weld seam, the cooling intensity of this unit being adjusted as a function of the actual value representing the gap
REFERENCES:
patent: 5204505 (1993-04-01), Prange et al.
Alber Gerhard
Schmeh Alexander
Mills Gregory
Thyssen Industrie AG
LandOfFree
Process and device for cooling the area of a weld during laser w does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process and device for cooling the area of a weld during laser w, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process and device for cooling the area of a weld during laser w will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-244000