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REIS - Laser material processing systems
Laser technology in conjunction with robots with integrated beam guidance has in the past years made its arrival in industry.
Laser technology in conjunction with robots with integrated beam guidance has in the past years made its arrival in industry. Especially in the processing of plastic materials, e. g. production of interior trim components for the automotive industry, extremely economic new production technologies and procedures have been developed. Nearly 150 robot systems from REIS are now in industrial use worldwide. As a robot manufacturer on the one hand, and as a system integrator on the other hand, REIS has in its own facilities the entire competence for further development of such technologies, for both the basic units and their application. With the continual development of laser technology further new application fields are being opened up in the processing of metallic and non-metallic materials such as glass, composite and other materials. Besides application-specific technical advantages being achieved, another advantage is the remarkably lower capital investment compared to CNC machines.
In the early 1990's REIS ROBOTICS had already made significant developments in the integration of lasers directly in the robot arm. Laser beam guiding integrated into the robot arm structure offers large advantages compared to conventional systems with external laser beam guidance or stationary laser systems where the part to be processed must be moved. The dexterity of the robot and the compact design of the slim wrist module ensure very good accessibility with minimal interference even on complex 3-D components with cuts to the reverse side. Fast cutting speeds and high path accuracies contribute to the overall economic efficiency of the systems. REIS ROBOTICS has many patents in this field. Since 1995, laser robots with integrated beam guidance have been offered both for CO2- and for Nd:YAG-laser. Initially the laser was mounted on the upper arm (axis 3) on these robots and the laser beam was guided to the tool center point inside the arm.
Continually rising demands of the laser system business prompted further developments with new kinematics concepts for the use of lasers on robots. The arrangement of the laser on the upper arm (axis 3) to some extent limited the movement, dynamics (speed and acceleration) and the accuracy of the robot due to the resulting high mass accelerations. Additionally the interference of the laser head module in the work envelope, due to its large size, also had a partially negative effect. Furthermore carrying the weight of the laser head in its position, and giving due consideration to the load capacity of the robot, it was only possible to use lasers with an output power of 600 W. These marginal conditions resulted in the introduction of new developments of the robot kinematics for the use of laser.
The concept of the new REIS Laser Robots RV6L-CO2 and RV16L-CO2 addresses the issues of the above mentioned disadvantages and limitations. Unlike the standard positioning of the laser on the upper arm, it is now mounted laterally on the swivel arm of axis 2 (lower arm). Due to this positioning near to the robot base it is possible to carry laser beam power sources having a weight of up to 400 kg, making it possible to integrate lasers of several kilowatts capacity without impairing the available work envelope. Due to the favorable arrangement of the mass, this optimizes position to minimize any impact on the robot dynamics. In addition, the lower acceleration forces of the laser head enhance overall operation time. A universal interface allows the use of many different laser types from several manufacturers. As with the earlier REIS robot systems, using the robot kinematics available since 2002, the laser beam is guided to the tool center point completely inside the robot arm via 4 or 6 mirrors at choice. Because of the centric position of the focus point in the direction of axis 6, in most cases only the 5-axes version is required for cutting tasks. In the event that additional application-specific components have to be adapted on the robot hand, a further hand axis (axis 6) is available. Thus, other process devices e. g. external cold wire feed for welding or sensors for seam tracking or for process monitoring, can be moved and oriented to the processing path during the machining process.
Starting from the basic components of the standard series of REIS robots, further robot kinematics were developed for laser processing. Hybrid kinematics, a combination of modules from the linear robot series (axis 1) and components from the articulated arm series (axes 2 to 6), allow machining of large components with a length of up to 25 m. This is achieved due to a suspended arrangement articulating axes on a longitudinal axis with expandable stroke length.
If the reach of an articulated arm robot in the transversal direction is not sufficient, the hand axis module with integrated laser beam guiding can also be used in a gantry robot, the laser being guided along on the gantry or installed stationary depending on the performance class. This kinematics concept, depending on the application, can be supplied with different stroke lengths in the linear axes and excels with its high path repeatability in the range of approx. 0.1 mm. This is achieved by the use of direct drives in the basic linear axes.
Depending on the application, different laser types in various powers from 100 Watt upwards may be adapted to the REIS ROBOTICS robots. In spring 2004, the company Trumpf from Ditzingen introduced the new diffusion-cooled CO2-laser TCF 1 with a power of 2 Kilowatt. This has opened the growing market between the compact sealed CO2-lasers of up to 600 Watt and the considerably bigger high-performance CO2-lasers. In a cooperative development with the company TRUMPF-Lasertechnik this innovative product was adapted to the WithoutREIS laser robots. Potential applications of the TCF 1 are in the laser processing of non-metallic materials such as glass, plastic, wood, and textiles. With its very high beam quality, K of 0.9, the TCF 1 is also suitable for processing of thin sheet metal.
Programming tools - expert functions
A prerequisite for the optimum use of robots for sophisticated machining tasks is that facilities for programming and operating the equipment offer the necessary comfort. Special functions were implemented in the REIS robot control ROBOTstarV to assist the user in program generation and optimization. Some possibilities of the programming tools are alluded to by their self explanatory titles, e. g. the expert functions MinMove and PatternInsert.
MinMove (Minimized Movement)
Speed and accuracy of a robot depend considerably on the scope and how certain axes have to be accelerated and decelerated. Since the basic supporting axes of a robot normally have the highest mass, their movement should be minimized and be taken over by the much more dynamic hand axes. The effect of deviation due to orientation resulting from this, at least for small contour dimensions or small material thickness, is so low that it is negligible. The programming assistant with the expert function MinMove here supports the user in automatic conversion of the robot movement. Based on the selected allowable deviation in orientation, the contour to be moved along is modified in such way that the basic axes movement is minimized transfer most or all of the complete movement into the hand axes. The movement, so to speak, is executed "just like that", which allows to reach extremely high path speeds with little path deviation.
This expert function allows selection of geometric movement patterns from a predefined library and PatternInsertparameterization of same in the dimensions. By use of the programming assistant, this pattern now can be automatically inserted at the desired position in the sequence program with the required program commands and process parameters . The position in space and orientation of the movement pattern on the component is defined by programming a space point. This is especially useful for often repeated patterns e.g. cutting of acoustic holes for loudspeakers in a car interior trim. The programmer is efficiently supported by the programming assistant.
In many applications for laser technology the accuracy that can be reached with robot systems is sufficient for the machining process. Due to the close integration of the laser in the robot kinematics it is possible to realize automation solutions which offer the user both technical and economical advantages. The variety of applications, covering a multitude of tasks with respect to necessary work envelopes and requirements for accessibility, prompted the use of the integrated laser beam guidance with different kinematics concepts. A further prerequisite for the use of robot technology is the availability of functions in the robot controls for simplification of programming and for monitoring of the machining process. REIS ROBOTICS has all the components for optimum use of laser technology in the processing of plastic and metal, as well other materials such as wood and glass. REIS can therefore provide a most comprehensive range of economic automation solutions for a wide variety of applications using this machining technology.
Dipl. Ing. Axel Fischer
department manager development
D -63785 Obernburg
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