Method and device for connecting the ends of steel tubes by means of orbital welding using a hybrid technique

Abstract

The invention relates to a method for connecting the ends of steel tubes by means of orbital welding using a hybrid laser arc technique, with the tubes preferably having wall thicknesses 6 mm and more particularly 12 mm and diameters of preferably 150 mm, the ends of which tubes are connected by one or more welding passes, wherein the laser and arc welding heads as tools are guided over a guide ring fixedly arranged around a tube end in the region of the weld site during the welding and are displaced around the tube diameter. The invention also relates to a device for carrying out the method, wherein the laser and the arc welding heads are positioned separately on the guide ring and are moved over the tube circumference and controlled independently of one another during the welding process.

Claims

1. A method for connecting ends of steel tubes by means of orbital welding using hybrid laser arc technique, comprising: providing said steel tubes displaying a wall thickness of at least more than 12 mm and diameters of at least more than 150 mm and being round or hollow tubes with varying cross sections; providing a first trolley on a guide ring, said guide ring securely arranged in a region of a weld site about a circumference of at least one of the ends of the steel tubes, said first trolley carrying a laser welding head; providing a second trolley on the guide ring separate from the first trolley, said second trolley carrying an arc welding head, said first and second trolley each having a respective motor for moving the first and second trolleys on the guide ring and thereby moving on the same guide ring at least two welding heads carrying out a hybrid welding process with at least two different welding processes including the laser welding head and the arc welding head, said respective motors being adjustable independent of each other so that with respect to the circumference of the at least one end of the steel tube an angular distance between a root of a laser beam of the laser head and an arc root of an electric arc generated by the arc welding head is variable during the orbital welding, said laser head having an angular optical fiber causing a 90 deflection via a focusing mirror; connecting the ends of the steel tubes with one or more welding passes by moving the first and second trolleys independent of each other about the circumference, said first and second trolleys guided by the guide ring during said moving; and moving on the same guide ring a third trolley carrying a further arc welding head for producing filler layers.

2. The method of claim 1, further comprising separately adjusting a speed at which the laser welding head and the arc welding head are moved during said moving and a distance between the laser welding head and the arc welding head.

3. The method of claim 1, further comprising preheating a welding seam region before commencement of the welding process by a preheating device which travels ahead of the laser welding head and the arc welding head.

4. The method of claim 3, wherein the preheating device travels on the guide ring independently from the laser welding head and the arc welding head.

5. The method of claim 1, further comprising moving further tools on the guide ring independently from one another during welding.

6. The method of claim 5, wherein one or more additional said welding head, a seam tracking system, a mechanical processing system of the weld seam and/or a system for non-destructive testing of the weld seam are used as further tools.

7. The method of claim 1, wherein the tools move on several guide rings arranged on one tube end or both tube ends.

8. The method of claim 1, wherein the metal inert gas welding (MIG) is used as arc welding process.

9. The method of claim 8, wherein the MIG welding is carried out using pulsed arc technique.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) Further features, advantages, and details of the invention are disclosed in the following description of the shown figures.

(2) It is shown in:

(3) FIG. 1 the principal configuration of the orbital welding device according to the invention with separately movable laser welding head and arc welding head,

(4) FIG. 2 like FIG. 1, but with further separately movable tools.

(5) FIG. 1 shows the principal configuration of the orbital welding device according to the invention for hybrid laser and arc welding of tubes.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(6) The tubes 1 have ends to be welded which are centered by an internal centering device, not shown here, and prepared in this way for being welded together.

(7) Arranged on the guide ring 2 which is configured as frame construction are a trolley 3 with a laser welding head 4 and a trolley 5 with an arc welding head 6 which can be moved and controlled independently from one another. Also not shown here are the power supply and the fluid supply of the welding heads as well as their control. The processing zone of the hybrid welding process on the tube 1 is designated with 7.

(8) Each of the trolleys 3 and 5 is equipped with a direct drive, not shown here, by which the independent movement is rendered possible with the assistance of a single drive system. The parallel arrangement of further direct drives and guides basically permits also the option to allow the trolleys to move past one another. In the case at hand, both trolleys 3 and 5 travel clockwise (arrow direction) about the tube 1, with the laser welding head leading the way.

(9) FIG. 2 shows a configuration in which additional tools are arranged on the guide frame. Same reference signs are used for same parts, with the following description centering only on the additional features of FIG. 2.

(10) Selected for the illustration is an arc welding head 6 which leads the laser welding head 4 in counterclockwise direction. Installed on a trolley 8 ahead of the hybrid welding process and thus of the two trolleys 3 and 5 for the welding heads 4 and 5 is a seam tracking system 9 which can be utilized for quality control (e.g. photo documentation of the weld seam, automatic seam measurement, flaw detection) after the welding operation. Trailing the welding process is a further trolley 10 which is arranged on the guide ring 2 and has a further arc welding head 11 for producing filler layers. As an alternative, this could also be, e.g., a tool for automatic grinding of seam ends or a system for non-destructive testing of the weld seam so that a seam can be checked without changing the guide ring.

(11) A compact structure permits an enclosure, not shown here, of the overall system for the purpose of laser safety.