Drives eliminate production stoppages for circlip maker
29 July 2013
Variable speed drives have helped a manufacturer of circlips to cut production stoppages – from typically three a week to none – as well as saving £11,000 a year in energy costs.
Cirteq buys raw, unshaped wire and runs it through various processes before the circlip is cropped, shaped, heat treated and finished. One of the first operations in the manufacturing process is to shape and draw the raw wire.
The machine used to perform this operation originally employed a very early type of DC variable-speed drive (VSD). The two main DC motors on this machine drove the shedding drum (the master drive) and the mill stand (the slave or follower). Used to shape the wire, these are controlled via a dancing arm that maintains tension in the drawn wire. The third motor, an AC motor, is used for the take-up or coiling drum and was controlled via an eddy current drive.
These motors and controls were becoming difficult to maintain, were inefficient and were unreliable. Bob Holinski, plant manager, explains: “The old DC motors were controlled using a Ward Leonard drive system and were starting to gives us various problems. Spares were no longer available and reliability was deteriorating. This had a big effect on production and we were seeing up to three failures a week, which took some time to rectify.”
ABB’s authorised value provider, Halcyon Drives, was asked to investigate the option of replacing the Ward Leonard drive system with high efficiency ABB motors and ABB industrial drives.
Halcyon Drives supplied a replacement panel, incorporating two 30 kW ABB industrial drives for the shedding drum and mill stand, controlled in master/slave via the dancing arm and a 7.5 kW ABB industrial drive for the coiling drum. This drive uses ABB’s direct torque control (DTC) to slow the rotation of the coiling drum to compensate for the rising torque as the wire increases the drum’s diameter. A control console linked to the panel allows remote control of the drives. The three motors were general performance IE2 high efficiency cast-iron 6-pole motors. All installation and commissioning, which took around two weeks, was undertaken by Halcyon.
“The size of wire determines the speed at which the machine should run,” said Holinski. “The previous system used a series of gears to alter the speed, which meant we did not have a great range of speeds. With the new VSD based system, we can alter the speeds of the drum easily using a dial on the control console, giving us better overall speed control. We now have a modern control system with readily available access to spares and full technical after care from Halcyon Drives.”
The machine runs 20 hours per day, six days per week, for 48 weeks a year, giving a saving of £11,000 per year.
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