Welding robotics

The third type of FSSW machine is a C-frame unit. The purpose of the C-frame is to contain the welding forces internal to the unit. This means that the robot or operator does not have to generate any of the forces required for the process. Thus, smaller robots can be used for C-frame FSSW than for FSW. The robot arm only manipulates the C-frame unit through space to the part that is to be welded. Robots that are used for RS W can also be used for FSSW. Typical C-frame FSSW units are shown in Fig. 11.7. 

The following numerical example illustrates these steps of the goodness of fit procedure. In a test of industrial welding robots 6 samples of 20 robots each were taken at random. Each robot in the sample operated continuously until it either failed or reached 1000 hr of operation. It is desired to verify if the true proportion of the entire population of robots that can operate over 1000 hr is 0.97. 

The system is for semi-automatic arc welding and consists of two stations xi/hich are used alternately by a central welding robot while work is being loaded/unloaded from one station the robot is welding at the other (Figure 1). All control functions (eg sliding door operation, control of the rotating tables etc) are carried out by the robot control system. 

American Welding Society (AWS) D16.1M/D16.1, Specification For Robotic Arc Welding Safety—identifies hazards involved in maintaining, operating, integrating, and setting up arc-welding robot systems. 

Early research in the field of robotics were made based on development environments working with cells fixed in their positions for the robot to develop its work, as in the case of the welding robot in an assembly plant. 

Figure 6 AIR-1 articulated robot arm with six degrees of freedom Robot performs ultrasonic inspection of a large nozzle weld on a BWR main circulation pipe.

Tiny machines such as Zettl s oscillator may be useful on their own but also in forming the components of more sophisticated instruments such as nanobots. Robotic automation is commonly employed in industrial factories to do jobs that require repetition or extreme precision, such as spot welding. Nanobots would have the added benefit of being able to function in otherwise inaccessibly small locations. Tasks for nanobots include scanning a load-bearing surface and looking for signs of structural failure that would be impossible for a human inspector to see. 

The human body, for instance, has sensors (eyes, ears, touch receptors in the skin, and so forth), a controller (the brain), and actuators (muscles) to react and respond to commands. These are the same basic concepts as the adaptive systems discussed in this chapter. Robots today, such as the welding machines used in industry or the toy dogs sold as pets, are extremely Umited in mobility and adaptability compared to humans. Yet smart materials, along with a design based on the sensory, nervous, and muscular systems of the body, could one day create an agile and adaptable robot. 

Ranky, P. G. (2002), A method for planning industrial robot networks for automotive welding and assembly lines, Ind. Robot Int. J., 29(6), 530-537. 

Robotic cables, including welding, automotive fabrication, body painting, and semiconductor manufacturing... 

In instances in which several similar structures are to be welded repetitively, an increased rate of production can be obtained by mounting a single torch or multiple battery on a mechanism of the pantograph type, so that several seams can be welded simultaneously. For repetitive applications, if desired, the hot-gas welding technique should be controllable by computer programme, and suitable for work with robots. 

R. Sakano, K. Murakami, K. Yamashita, T. Hyoe, M. Fujimoto, M. Inuzuka, Y. Nagao, and H. Kashiki, Development of FSW Robot System for Automobile Body Members, Proceedings of the Third International Conference on Friction Stir Welding, Sept 27-28, 2001 (Kobe, Japan), TWI, paper on CD... 

S. Brinkmann, A. von Strombeck, C. Schilling, J. dos Santos, D. Lohwasser, and M. Kocak, Mechanical and Toughness Properties of Robotic-FSW Repair Welds in 6061-T6 Aluminum Alloys, Second International Symposium on Friction Stir Welding, June 26-28, 2000 (Gothenburg, Sweden), TWI... 

Robots and Machines for Friction Stir Welding/Processing... 

FRICTION STIR WELDING (FSW) and its variants of friction stir processing (FSP) and friction stir spot welding (FSSW) have numerous equipment solutions for production and development applications, like most manufacturing processes. There are three basic categories of production equipment solutions for most processes manual, hxed automation, and robotic solutions. Production FSW solutions are similar, with the exception that a manual solution is generally not possible due to the high forces required for FSW and its variants. 

Robots have two main advantages that allow them to eventually be a preferred solution for many applications. The first is cost, and the second is flexibility. Because they are produced in moderate production volumes, their cost is significantly less than a custom-built machine. Additionally, they typically have much improved flexibihty. This flexibility allows for significant productivity improvements. As an example, consider a part with welds on multiple sides. A robotic solution can allow for welding on multiple sides of the part in a single setup. This reduces non-value-added materials handling applications and can yield 100% or more improvements in productivity. This, of course, reduces net welding cost. 

Dissimilar-thickness butt welds (tailor-welded blanks). Dissimilar-thickness welds require both a travel angle and work angle (a minimum of five axes of motion). Robots are ideal for this application. 

PLC). The weld schedule is stored internally or in the external control equipment. In the manual mode, the system is activated via push button or operator interface. In the automahc or robotic mode, the system is activated via communication from a PLC or robot. 

Control Strategies. There are two basic control strategies found with FSW and FSSW force and position control. Force control can be very desirable in many apphcations. It is often the case that FSW has a larger operating range with respect to thrust force than vertical position. Thus, it can he a more robust control strategy. This is especially the case for butt welds. Additionally, force control tends to be preferred for less stiff machines (e.g., robots). 

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