An industrial robot has been defined as 'a re-programmable device designed to both manipulate and transport parts, tools, or specialised manufacturing implements through variable programmed motions for the performance of specific manipulating tasks'.
In the field of joining, robotic devices may be found performing the following tasks:
- Cleaning (with grit or water blasting)
- Joining (arc, laser, resistance and friction stir welding , riveting and adhesive bonding)
- Handling (placing components into pedestal-type resistance welding machines)
- Coating (paints or metal sprays)
In performing these tasks, the robot arm moves, through a volume in space, either the tool which performs the work, or the component on which work is done. There are six basic configurations that do this:
(c) Revolute/Jointed arm
On the end of these arms is normally a wrist mechanism (with 2 or 3 axes of movement) which enables the tool or part to be orientated.
Robots are computer controlled, servo feedback systems that move smoothly, precisely and at considerable speed through a programmed path. Being computer-based, the programs can be readily reconfigured (re-taught) to enable new tasks and operations to be undertaken.
Programs were initially generated by driving the robot, point-to-point, through the required path while recording each point in turn. This approach requires 'on-line' use of the production robot. Increasingly, computer simulation tools are used to generate, 'off-line' programs which are then down-loaded to the robot when required.
Welding is a key task for industrial robots, with 25-35% engaged in arc welding and 30-40% performing resistance welding tasks. The automotive sector is the major user (50-60%) but yellow goods (earthmoving equipment) and white goods (washing machines, refrigerators, etc) are growing sectors.
What are the differences between mechanised, automated and robotic welding?
Steeling the competitive edge: is there a place for robots?
Manufacturing - dynamic simulation