17-01-2011, 07:28 PM
Vacuum systems for successful robot implementation
ABSTRACT
The design of a vacuum system and choice of vacuum components for robot end effectors can be of crucial importance for a successful robot installation.This paper discusses vacuum solutions for robot end effectors, which increase the possibility of a successful robot installation.
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1 INTRODUCTION
We live in a world with shortened product life, an increased variety of products and a demand for higher quality on the products. Continuous productivity improvement goes without saying. At the same time, increased safety, reduced environmental impact and better working conditions become more and more important. A successful robot implementation has to improve the production flexibility, increase throughput or raise the quality of the products and reduce the manufacturing cost. There is also a trend for lower environmental impact from production.
PIAB is a global company and has been working with industrial vacuum technology for over 30 years. We have and have had several important innovative patents concerning vacuum technology based on ejectors. Technically and organizationally PIAB is operating in several market segments such as packaging and automotive. In all of the industries we have noticed a more frequent use of robots for material handling. The basic principles for a successful robot implementation using vacuum are similar for most applications and industries. We would like to share our knowledge about how to design vacuum systems for robot end effectors by giving some useful vacuum guidelines related to important matters for successful robot installations.
2. IMPORTANT CRITERIA FOR A ROBOT INSTALLATION
2.1 Increased productivity
One way to increase the production rate on a robot material-handling line using vacuum is faster air evacuation of the system so that the robot can start the motion earlier. If it is a leaking system, as when handling porous material, for instance, the ability to maintain a satisfactory vacuum level is equally important. The most effective system is where vacuum is generated as close to the suction cups as possible. Such a system eliminates unnecessary hose volume to be evacuated and the risk of reduced performance due to restrictive piping. This fact excludes mechanical vacuum pumps as a part of an effective vacuum system for end effectors. In spite of that, many companies choose to have a centralized vacuum solution with the pump far away from the suction cups. The reason is weight saving, simplified vacuum control/management and quicker change over-time for service or component/tool changes.
A new, patented technology for building multistage vacuum ejectors in the form of a nozzle cartridge with built-in flap valves and filter challenges many of the arguments for a centralized vacuum solution. The nozzle cartridge is made of light materials and can easily be integrated directly into suction cup fittings or the boom structure of robot end effectors. Changing or cleaning the cartridge is quick and easy
and it can be done without any tools.
PIAB vacuum pumps
PIAB vacuum pumps are compressed air-driven vacuum pumps. The unique construction makes maximum use of the compressed air and therefore consumes less energy. Large vacuum flows and high levels of vacuum are characteristic of PIAB’s vacuum pumps.
When compressed air (1) passes through the nozzles (2), air is pulled through with the stream of compressed air. "Suction" is thus created at the opening of each stage (3).
Fig. 1 – Multistage ejector cartridge for efficient
decentralized vacuum systems
Choosing an efficient multistage vacuum ejector instead of a single-stage ejector can reduce evacuation time and substantially increase the possibility to speed up cycle times. Clear signals to start a robot motion are usually at vacuum levels between 30 to 50 –kPa [9 to 15 –inHg]. State-of-theart multistage ejectors are up to twice as fast to reach those levels as compared to single-stage ejectors, with the same air consumption.
Fig. 3 – Response time for evacuation of 1 litre for a single-stage and multistage low-pressure ejector with the same air consumption
Advantages of using multi stage ejector
