Extrusion Puller
Edwards of Enfield developed a very successful extrusion puller powered by Linear Induction Motors for application within the aluminium industry.
The puller takes advantage of the LIM thrust speed characteristic to exert a low-speed, high-thrust pull on a gripper head. This gripper holds the end of the hot extrusion while the LIM applies controlled tension. As it is extruded from the hydraulic press the aluminium requires a constant tension to keep the 45m (150ft) extrusion straight and free from twist.
Once the puller has travelled its full length the gripper releases the metal and returns to the start of the line at high speed and low thrust. Then it grips a new piece of material and the process is repeated indefinitely.
This development offered considerable improvement over previous drives, eliminating manual and rope/chain tensioners thereby increasing operator safety, productivity and profitability. Reliability was improved at the same time as reducing maintenance requirements.
Between 300 and 400 LIM puller systems have been installed world-wide, of which more than half were supplied by Force Engineering Ltd.
Several drive sizes and speeds were developed. The least powerful pullers up to 120kg (250lbs) use fan cooled LIMs whilst the more powerful ones up to 800kg (1750lbs) use water cooled units with on board closed-loop water cooling.