Automated task planning for industrial robots and laser scanners for remote laser beam welding and cutting

Abstract

Remote laser beam welding and cutting can be applied to a wide range of applications within the manufacturing technology domain. With high process rates, consistent high quality welding seams and cutting edges at various contours these technologies offer an increased flexibility to process a wide variety of work pieces. To take advantage of the process the laser beam must be positioned precisely on the work piece. Programming a system of an industrial robot combined with a laser beam deflecting scanner manually is a very time consuming job. Programming any ''on the fly'' movements, a synchronously movement of the scanner and the robot, is even more difficult. This paper describes challenges and a concept for the automated programming of the two devices to apply the advantages of remote laser beam welding and cutting. Remote laser beam welding and cuttingRemote laser beam welding (RLW) and cutting (RLC) (see Fig. 1) facilitated by their contactless process and their high operational speed, are versatile technologies with promising futures [1-3]. The remote technology allows the user to program any desired welding seams or cutting edges without running the risk of collisions between the laser forming optics and the work piece or its clamping device [4]. The versatility of remote systems is increased by combining both processes in one optics. Since no specialized hardware is needed for either process, the changeover between RLW and RLC is controlled by a software and can be integrated into an automated path planning.Compared to resistance spot welding a process presently used mainly in the production of automobiles, the application of RLW can reduce the cycle time by up to 80% [5]. A comparison of RLC to a conventional laser cutting linear drive machine also shows a great potential for reducing production times [6,7]. However, there is still a large amount of research to be done for both techniques on the programming of the used devices. At the moment, the application of robotic based RLW with scanners is profitable only when dealing with lot sizes of over 100,000 pieces per year or those that require numerous welding seams per work piece [3,5].Research work on RLW and RLC can be broken down into two fields [8]: First, reviewing and analyzing the process in order to gain a better understanding of the handling of the work piece is essential. Finding the optimal parameters for the laser power, speed of operation and valid inclination angles is one goal in the field of process studies [2,9]. Secondly, the focus of the laser must be positioned precisely on the work piece [4,10]. This paper deals with an algorithm for the automatic path planning of a robot and scanner based positioning of the laser beam. The introduced method offers more flexibility in specifying information for the welding seams and cutting edges when compared to programming the robot motion manually.

Remote Laser Welding with High Power Fiber Lasers

“…The welding speed is dependent on the laser power used, which is normally 6 m/min and up to 30 m/min for special plates [27]. A remote fiber laser welding system can weld more than twice as fast as either MIG or resistance spot welding [24].…”

“…A remote fiber laser welding system can weld more than twice as fast as either MIG or resistance spot welding [24]. The elimination with the scanner of non-productive time means that the cycle time of RLW can be reduced by up to 80% [4,27]. The continuous motion of the scanner head in combination with the rapid positioning makes the RLW system move the laser beam between welds in less than 50 milliseconds, while robot positioning typically takes 2 -3 seconds [3,17].…”

Remote laser welding with in-line adaptive 3D seam tracking

“…Welding simulations help with teaching of a welding path [14,15], but this does not take into account the thermal deformations that occur during welding, unrepeatability of clamping, shaking of a robot manipulator during movement, and synchronization between the robot controller and scanning head controller. All this leads to lesser quality welds and products.…”

Process Stability during Laser Beam Welding with Beam Oscillation and Wire Feed

“…For laser welding with aluminum, the addition of a filler wire is often indispensable [7]. The laser is a widely used tool in welding technologies featuring low distortion and high production efficiency [8]. Its concentrated energy focus on the material surface allows deep penetration welding due to the existence of a keyhole [9].…”