Broken rotary bridge helps metering low flow materials


A pneumatic device deployed inside one of the hoppers in a gravimetric mixer would make possible precise dosing of regrind, recycled plastics and other ingredients that tend to clump or “bridge”, clogging. flow through the hopper distribution valve.

Maguire Products Inc. introduced the new “bridge breaker” for its three largest series of mixers, those with maximum flow capacities of 5,000 kg / h (11,000 lb / h) and the capacity to mix up to twelve ingredients. The bridge breaker consists of a hopper insert that directs material directly down onto the distribution valve; and a rotary device which operates automatically when the dispensing valve is opened. The device quickly oscillates between clockwise and counterclockwise movements, improving material flow through the dispense valve.

The hopper insert, which offers a vertical alternative to the sloping wall of the hopper, can be retrofitted into any mixer currently in operation. To compensate for the space occupied by the insert, the complete hopper assembly includes an extension to accommodate the desired amount of material.

“The new bridge breaker responds to the growing demand for recycled content in plastic products and the increasing use of regrind as a means of reducing production costs,” notes Frank Kavanagh, vice president of sales and marketing. “More and more processors are finding it difficult to maintain a constant flow of such materials. In fact, we developed the bridge breaker to help one of our customers solve a scrap metal problem.

The three families of high capacity Maguire blenders, the 1200, 2400 and 3000 series, blend up to 12 ingredients, using a wide range of removable hopper and feed configurations and numerous dispensing devices. Mixers process raw materials in various forms, including ordinary granules and regrinds, bulk powders, flakes, and ingredients particularly prone to bridging, such as wood flour.

As with other Maguire scale mixers, once all the ingredients are dosed into the weighing chamber, the batch falls into a mixing chamber. A microprocessor makes batch-to-batch corrections, including adjustments to compensate for variations in extrusion rate or bulk density, maintaining overall batch accuracy within ± 0.1%.


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