The gas nozzle itself is used as a sensor. This makes it possible even on complicated workpieces and in confined spaces to perform the required search trips on the reference surfaces of the workpiece, by which the position of the weld seams is determined. As soon as the gas nozzle comes into contact with the work piece, it is discharged and the robot stops immediately. This discharge is recorded on-line by the respective sensor board in the control cabinet and subsequently the robot moves to the next searching run.
Arc seam sensing - precision welding of fillet and V-seams
During the welding process arc seam sensing is used to compensate for positional tolerances of the welding seam.
By means of a special software and specifically designed hardware, the "actual" seam position of fillets and V-shaped joints is computed by processing data measured while arc weaving, giving a corresponding shifting of the original programmed point/s to the true seam position. This arc seam sensing technique can be used with a complete range of welding transfers such as short arc, spray arc and pulsed arc welding - using single or Tandem applications. The welding gun then follows the exact path of the seam joint.
This process can be advantageous in combination with gas nozzle sensing. There, the starting point of each welding seam is detected by the sensor and the arc is ignited at the correct position with the desired stick-out.
igm laser camera iCAM
So that the robot finds always the right direction, extremely effective compact laser cameras are used. They are designed for tracking different welding seam types, for identifying and measuring detected gaps, and for compensating volumes.
The camera is based on synchronized laser scan technology, featuring high speed stability, large and programmable workspace, deep visual range, and robustness regarding ambient light and reflections. Impassivity against high frequencies and magnetic fields makes it an ideal device for many industrial processes under rough conditions.
The igm laser camera iCAM is mounted on the wrist axis of the robot. It measures the position and volume of the weld groove online and adjusts the robot movement and the welding parameters accordingly. For the purpose of welding in narrow workpiece ranges, the camera can be automatically deposited and readopted during the welding program.This igm developed laser camera iCAM offers as an outstanding feature the complete integration into the robot control. Thus programming is done with the igm teach pendant K6 without the need for an additional PC. The user benefits from the wide range of languages, European as well as Asian ones, being supported by the robot software. By means of the logging function the whole joint geometry can be displayed, indicating gaps and volumes. A live view of the measuring field is given by grey scale value image. Optionally the camera can be mounted to a rotation device, integrated in the robot controller as sensoraxis.
igm laser sensor iLS-C
The igm laser sensor iLS-C is useful for applications where edges or gaps must be searched for. The sensor is conceived to detect deviations between the actual work piece position and its original position. Shifting is computed in parallel as well as in 3D mode, effectively compensating height and width deviations.
Compared with conventional tactile sensors, the laser sensor essentially reduces non-productive times by using high search speeds and by simultaneously detecting height and lateral position during a single search path. The well-designed teach pendant supports easy programming; special knowledge regarding processing algorithms is not required.
iLS-C shall typically be applied in those cases where tactile sensing is not possible due to sheet thicknesses and / or accessibility.
Detection is initiated by moving the sensor with the robot torch across the seam to be searched for. Always the entire search sequence is performed and then the image is analyzed. Thus interference such as peaks, freak values (mirror effects) or parasitic objects (spatter formation and debris) may be identified and filtered out. The seam type to be searched for must be assigned to the search sequence. The sensor computes the detected point's absolute position according to certain robot parameters and transmits the data to the robot control system.