For a car manufacturer, it makes sense to install multi-talented robot types because they can handle so many different tasks
- Ten years from now, thermal welding technology will likely still be dominant.
- The latest welding technology is multi-talented and light.
- Flexible mounting of welding robots has several of them handling a car body at the same time.
By Ola Svanstrom and Nicholas Sheble
Robots are multi-talented. They perform a number of different tasks with high precision, high speed, and heavy loads.
When a specific task-and only this task-is required, it makes sense to use a customized version of the multi-functional robot. An example of this highly specialized expert robot is one that sorts different goods with very high speed. Spot welding in the automotive industry is another example where talented "professionals" are of high value.
Reach under car frame
Modern assembly lines for car manufacturing are chock full of robots.
Most of these robots look like the ones we expect to see: They have a long arm with a "hand" that can bend forward and backward and turn around like a golfer in a full swing.
However, there are other mechanical movement systems in place that normally would not be what we call "robots," even though they work in a way similar to their more prominent relatives. These robots can weld, grip, move, lift, sort, paint, grind, or hold parts of a car together to help other robot colleagues perform different tasks in an optimal way.
For a car manufacturer, it makes sense to install multi-talented robot types because they can handle so many different tasks without making major adjustments.
When we look at the automotive support robots that join parts, it turns out the majority of them today are there for thermal welding. Thermal welding can use one of several technologies: conventional spot welding, laser welding, and laser soldering or friction steer welding. Regardless of the specific technology, the same robot can operate the thermal joining mechanism.
Ten years from now, thermal welding technology will likely still be dominant when compared to mechanical joining or chemical methods. Given this trend, and the growing requests from the automotive industry for higher flexibility and lower cost, it makes sense to complete the portfolio of robots in an assembly line with specialized welders.
The latest welding technology is multi-talented and light. It is more compact than previous machines, and it saves valuable space in the production line, which allows the hosting of two welding specialists-one may be hanging from the ceiling or mounted on a second working level in relation to the moving car body.
Its agility is such that it can actually reach under a car frame to perform less accessible welding operations.
System with three light arms
Robot controllers have made gains too, and they allow for coordinated movement of several robots and simultaneous working on the same piece. If the new agile welding robot connects to such a system, other robots can position the work piece for welding.
Due to the flexible mounting of these welding robots, several of them can handle a car body at the same time and even reach below or into the car without disturbing each other.
Safe movement concepts ensure a collision-free operation at all times.
While the robot-specialists dance around the car body and weld with high speed in all corners, the multitalented mechanic can concentrate on the manifold other operations.
This combination of generalists and specialists opens up manufacturing to radically new concepts. Through this achievement, respot lines get shorter and faster with eight robots working simultaneously.
The assembly of body sides and roofs becomes more flexible and faster when spot welders and power robots help each other. This increased flexibility is highly appreciated by the automotive industry.
It supports the trend to manufacture more car models on the same line, which not only speeds up the process but also enables optimal use of the valuable assets in the production line. A modern assembly line cannot effectively work without specialists that support the multi-talented robots.
There are specialists for quite different applications. One is a picking robot that is a system with three very light arms and a gripper that can lift and transport light items such as chocolate pieces or pralines and sort them into boxes. Some robots would be too slow for this even though they could perform more functions in the sorting process.
The concept of specialist robots is gaining ground in industry.
Whenever mass production of parts is required, a specialist may very well be the more flexible and economic
ABOUT THE AUTHORS
Ola Svanström (firstname.lastname@example.org) is a 20-year veteran and manager at ABB Robotics. He has a M.Sc. in mechanical engineering and an MBA. Nicholas Sheble (email@example.com) is senior technical editor at InTech.
A flexible robot for picking and placing is a so-called parallel kinematics robot.
In contrast to conventional industrial robot designs, in which articulations sit in a serial manner along a single arm, a parallel kinematics robot has three or more parallel arms supporting a manipulator.
All of this flexible picker's motors and gears are in its base. This makes the moving parts very lightweight, contributing to the robot's agility-accelerations above 10g are possible, and handling rates can exceed 120 items per minute.
The designers of this robot had hygiene on their minds. There are no painted surfaces, and one can wash it with low-pressure water and without detergents. It is suitable for handling food.
The conveyor-tracking functionality of the controller permits the FlexPicker to pick and place on a moving conveyor, eliminating the time-consuming need to start and stop the belt for every object. Furthermore, the software permits the robot to identify and pick irregularly arranged and shaped objects, which show up frequently in food processing.
Continuous flow-discrete products
Manufacturers are in pursuit of automation solutions that increase productivity through higher line speeds while maintaining the agility necessary to handle a wide range of products.
IEEE 1588 enables such performance by providing precise synchronization among modular machine sections while reducing life cycle cost.
The IEEE 1588 Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems is a viable foundation for standardizing the way modular machinery connects.
Network services available with the IEEE 1588 standard will enable rapid integration of modular machinery that will operate in precise synchronization. Robotic production lines are excellent automation candidates for utilizing the capabilities of IEEE 1588 as they are widely used in continuous flow operations for discrete products and perform tasks while work in process are still in motion.
Many automated production and warehouse applications such as assembly, welding, printing, or material handling are traditionally implemented with centralized command and control centers, making them costly to integrate and difficult to support.
However, the market is shifting as end users are in pursuit of automation solutions that offer continuous flow operation for discrete products to increase productivity through higher line speeds, while maintaining the agility necessary to handle a wide range of products.
Machine builders are responding in parallel to these functional requirements with modular machine designs that allow end users to configure manufacturing systems based on functional subsystems.
Robots are excellent automation candidates when implementing continuous flow by performing a task while subassemblies or work-in-process are still in motion. Synchronizing the robotic motion with the conveyors within its operating zone, increases overall productivity.
Algorithms to synchronize robotic operation in reference to a moving conveyor enable such operation, even if conveyor speed changes continuously. Eliminating start and stopping operation of conveyors increases the average line speed by making parts move continuously. IEEE 1588 could enable operation with ease and in an open environment.
Robotics are widely used in the automotive industry for automated assembly, welding, painting fabrication, and production lines. Consequently, automotive manufacturers are constantly searching for ways to increase production or transfer line speeds for faster return on assets.
Raising the speed notch by notch on every section or station of a production line, to the point beyond which production quality might suffer or until a process bottleneck occurs, is one way manufacturers achieve high line speed.
Source: ARC Advisory Group (www.arcweb.com)
Dancing in the dark
Robot controllers have gained superior functions. One of these is the MultiMove, which permits the synchronization of up to four different robots or positioners.
That means it calculates the movements of up to 36 servo axes.
Without such synchronization, a positioner might first have to move a work piece into position and then stop.
A welding robot would then approach the piece, weld, and withdraw. Only when the robot had come to a halt could the positioner turn the piece to permit the robot to work on the other side.
Saving time happens using the newer functionality by allowing many of these movements to take place simultaneously.
The welding robot can move towards the work piece as the positioner brings it to the robot, and the positioner can slowly rotate the work piece while welding is in progress.
The resulting continuous weld enhances the quality of the final product.
The functionality also permits several robots to weld simultaneously.
The resulting time savings augments throughput.
Spot welding is a type of resistance welding used to weld various sheet metals. The process uses two shaped copper alloy electrodes to concentrate welding current into a small spot and to simultaneously clamp the sheets together. A strong current passes through the spot melting the metal and forming the weld. The time for a weld is quite short and does not heat the rest of the sheet.
Laser beam welding is a welding technique that joins multiple pieces of metal through the use of a laser by leveraging a concentrated heat source, allowing for narrow, deep welds and high welding rates. It is big in high volume applications like the automotive industry.
Friction steer welding is a welding process in which the head of a rotating pin moves along the welding seam. The frictional heat and clamping pressure cause the parts to forge together without melting the metal. This method works with aluminum.
Respot is the process providing the final weld after initial welds are holding parts in position.