CBW Automation, Fort Collins, Colo., a manufacturer of high-speed automated retrieval systems uses vacuum and suction cups to grip and transport products coming out of plastic-injection molding machines. The OEM had been using rotary vane pumps to generate vacuum for the machine, but designers wanted a more energy efficient solution — and one with less required maintenance. An efficient and reliable vacuum source is critical for serving high-production machines, so designers switched to venturi-type air-driven pumps. This change addressed several shortcomings they saw in rotary-vane pumps: low free-flow vacuum performance, noise, heat generation, large size, and high maintenance costs.
High-speed, side-entry robot system generates vacuum with air-driven pumps.
CBW considered using PIAB’s Classic M venturi-type vacuum pumps but was concerned about the volume of compressed air they would consume. By ordering pumps with an energy saving (ES) option, air use was kept to an acceptable amount. The ES modules work like a thermostat — as soon as the required vacuum level is reached, a valve blocks inlet flow to the pump, minimizing the compressed air consumption. If vacuum drops below the startup level, the ES restarts the pump automatically.
CBW’s vacuum-source design consists of the Classic M pump with ES option protected by a vacuum filter, a vacuum transducer, and one or more 3-way air valves. During normal operation, the valves are closed, and the pump builds vacuum in a closed circuit. The energy saving option then maintains the desired vacuum level with almost no compressed air consumption.
Energy saving modules — on right face of air-driven pumps — control inlet flow.
When vacuum is needed to capture a part, the appropriate valve opens, and vacuum builds between the vacuum generator and the part. The ES module maintains desired vacuum during product transfer. By designing for nearly leak-free sealing on parts the robot handles, the vacuum system consumes very little compressed air for each machine cycle. When the machine is ready to release the part, the appropriate valve closes to block vacuum, and a short burst of compressed air routed to the open port rapidly pushes the part from the suction cup.
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