Pneumatic conveying of punched metal parts using negative pressure is a real challenge. Johnson Controls is generally using negative pressure systems for conveying of punch waste in the production of lead-grids for starter batteries for automobiles. For a new production line of battery-grids the company selected a positive displacement blower.
Conveying of powders through a pipe system by means of negative pressure is a well known technology. In contrast to this, pneumatic conveying of punched metal parts using of negative pressure is a real challenge. This is even more the case, if small, differently shaped lead plates with a high specific weight of 11.37 g/cm³ have to be transported. At Johnson Controls in Hanover, Germany, approx. 11 t/h of such lead plates have to be conveyed in round-the-clock-operation via a route of approx. 50 m length with several narrow 90°-bows onto a height of approx. 6 m. In all their plants worldwide, Johnson Controls uses negative pressure conveying for the transport of punch waste in the production of lead-grids for starter batteries for automobiles. For a new production line of battery-grids at the plant in Hanover the company selected a positive displacement blower of Aerzener Maschinenfabrik to provide the required negative pressure.
Back into Production Circuit
Johnson Controls is one of the worldwide leading manufacturers of lead-batteries for automobiles and of progressive energy storage systems for Hybrid- and electric vehicles. Within the large brand portfolio of Johnson Controls, Varta, one of the most widespread battery brands worldwide, is known for high quality, innovative technology and technical experience gathered in the course of many years. At the Varta-plant in Hanover particularly high targets for the application of trend setting technologies and the careful and sustainable handling of resources are set.
Starter batteries for automobiles consist of a serial connection of lead accumulator-cells. They are formed by lead grids which have formerly been cast at Varta-plant in Hanover and positive and negative plates as illustrated in Fig. 2. “Today we produce these lead grids in fully-automatic production lines in Hanover“, explains Ahmad Abu-Shaqra, project manager at the European battery facilities of Johnson Controls.
First of all, an endless slab is formed from the melted lead, which is then transformed into a thin lead band in a rolling mill. From this, the lead grids are produced in a fully-automatically punching station. During this punching procedure only a slight fraction of the material remains in the product. Most of the remainder – very small lead plates in different forms with a specific weight of 11.37 g/cm³ – is led back to the melting facility to enter the production circuit again.
Johnson Controls had selected a suction conveying solution to return the punch waste back into the melting process after several alternative tests. With this solution the punch waste is sucked into a piping system be means of negative pressure at the punching facility and conveyed to the melting station. Up until recently, all production plants in operation were equipped with positive displacement blowers of US production.
Positive Cost Benefit
„First of all we wanted to install a complete new production line at our plant Hanover including a new positive displacement blower of US origin for the negative pressure conveyance of the punching parts. Finally however we relocated a production plant, already existing in another plant in the USA, to Hanover, but without the existing positive displacement blower. After evaluation of a cost-benefit-analysis we have taken the new production line into operation with a positive displacement blower of the series Delta Blower Generation 5 of Aerzener Maschinenfabrik at the beginning of 2010“, explains Ahmad Abu-Shaqra.
Aerzener Maschinenfabrik has been manufacturing oil-free compressing positive displacement blowers since 1868. The company is one of the worldwide oldest and largest manufacturers of such machines and today's market leader in Europe. With the current “Generation 5” Aerzener Maschinenfabrik offers the user a number of additional advantages:
- Easy operation and maintenance exclusively from front side.
- Oil level control by sight glass visible from outside.
- Space-saving side-by-side-installation next to each other without gaps.
- Ventilation of all units with acoustic hood by mechanical fan on the blower shaft without additional electric motor.
- Noise level reduced by an average of approx. 6 up to 8 dB(A).
- No sound-insulating adsorption material thanks to intensive air deflections in the base support.
- Atex-design available as option.
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