More control allows more flexibility
May 11, 2011
Robotics gained a foothold in industry because they can work in environments that are hot, toxic, or otherwise dangerous. The drawback was the programming, which initially was tedious and time-consuming, especially for precision tasks such as welding. Advancements in tactile sensing systems, automated arc welding controls, and software for tube and pipe welding have helped to spread robotic welding technology.
Editor's Note: This question-and-answer article probes new automation technology with Enrique Pano, ABB Robotics press automation manager.
A: Stampers have always been pressured to improve material handling while reducing costs to stay competitive—with safety always at the forefront.
What has changed is the business environment. There is more uncertainty. Design changes are happening faster, and every player has to be prepared for them.
Because of this, cost-effective systems and shorter paybacks are required to justify an investment. Other factors like flexibility, ease of use, and energy efficiency are equally important.
A: Robotic automation can provide more flexibility than hard (nonrobotic) automation.
New press lines use a network to facilitate communication between the automation equipment and the presses. More information is being accessed. Using today's technology, stampers can be more aware of what is happening on the line in terms of uptime, cycle time, bottlenecks, and so forth. This makes it easier to optimize production and reduce downtime.
A: Key factors for robots used in press automation are torque and acceleration. Current-generation robots include enhanced motion control to improve path accuracy and shorten cycle times. New software- and electronics-based safety features are available to ensure safe and predictable robot motion within a flexible operation and replaces electromechanical position switches.
For example, recent proprietary software can define a detailed 3-D work zone to optimize cell size and simplify safeguarding to protect both operators and machinery. It restricts robotic motion to either inside or outside of a defined zone. It also restricts tool orientation.
The new software replaces electromechanical position switches to increase control and flexibility and reduce maintenance. All of a robot's axes can be supervised through this software and can be used to define complex working envelopes for a robot.
New control software sets speed at a defined pace so that an operator can work within the proximity of the robot. It supervises the speed of all robot parts, including the tool-center point and individual axes.
New software provides a simplified interface between the robot and operator (see Figure 1). A robot teach pendant is equipped with a color touchscreen that interacts with the robot graphically to simplify the programming of new parts and paths. This way an operator doesn't have to be a programming expert, which can reduce the cost of training and programming time.
Another new development is a flexible crossbar, installed at the robot's wrist to provide additional linear motion for the part as it moves from press to press or between any other two points, such as in destacking (see Figure 2). The device's servomotor is controlled by the robot controller as an additional axis, which allows full motion control.
Moving parts linearly (without a 180-degree rotation of the dies) offers the potential to condense lines, as well as to accelerate cycle times. Automatic tool changes can be installed the same way as with standard six-axis robots.
A: A new technology that improves cycle time and part quality is the installation of a servomotor on mechanical presses (new or retrofit). The idea is to have the servomotor control and speed the slide motion but use the energy of the existing flywheel, engaging the clutch at synchronized speed just before the press draws the part. The benefits of this hybrid working mode are increased productivity (better cycle time); improved synchronization between presses and automation; improved quality (pressing at lower speed with same productivity); reduced maintenance (brake is not used, synchronized clutching, smooth press start and stop); and reduced peak power and energy consumption (no changes in installation).
Throughput requirements are always increasing. At the same time, stampers need highly flexible systems that enable them to change over production quickly with minimal labor. Vision systems are becoming more widely used for part centering, inspection, and quality control. These systems generally are highly flexible.
The market for robotic automation has grown in the past five years. Stampers are increasingly looking to a single source to integrate concept development, system engineering, project execution, physical installation, start-up, and production support. Also, having one responsible supplier reduces project risk and complexity.