Product category:
Drives, motors and power transmission, couplings, clutches
News Release from: Control Techniques | Subject: Unidrive
Edited by the Manufacturingtalk Editorial
Team on 08 June 2000
Unidrive with DeviceNet simplifies cable
winder
A despatch-winding machine, recently installed at BICC General UK Cables in Wrexham, features a new approach to the design of the drive control system.
A despatch-winding machine, recently installed at BICC General UK Cables in Wrexham, features a new approach to the design of the drive control system Control Techniques' Unidrives connected by DeviceNet to the controlling PLC has provided benefits to the machine builder and end user alike
This article was originally published on Manufacturingtalk on 11 Feb 2002 at 8.00am (UK)
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The semi-automatic, twin-head despatch winder, made by Meltech-Larmuth at their Blackburn factory, uses all three control modes - open-loop, vector and servo - of the Unidrives to their full potential.
In conjunction with the two-wire serial communications of DeviceNet, this has simplified the design and construction of the machine, cut installation time and given additional user benefits including improved diagnostics and easier maintenance.
"The combination of Control Techniques' Unidrive and DeviceNet have streamlined the whole process of design, build and installation," says Meltech's Electrical Engineering Manager, Andrew Proctor.
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"Unidrive is very versatile and eliminates the need to accommodate a number of different drives in the scheme.
They are all the same size and are programmed in the same way.
The system of plug-ins to provide extra functionality and programming capacity is excellent.
What's more, Control Techniques was also able to offer us a perfectly matched, and very compact, servomotor for the traversing head and this has proved ideal," he says.
What's more, the additional benefits of DeviceNet working with Unidrive has given BICC comprehensive diagnostics as standard and the substantial reduction in wiring and the 'plug-and-play' approach have greatly simplified both installation and maintenance.
BICC's requirement is for the rewinding of cables from 2.3m diameter process drums, holding up to 9 kilometres of cable, onto customer reels, with flange diameters from 400 to 850 mm in 100 or 250 metre lengths.
"It was necessary to keep manufacturing costs competitive by providing a dedicated cutting and packing facility.
As a similar smaller machine had proved itself at our Blackley plant, we decided to order a dual reel winder from Meltech-Larmuth," explains BICC General's Manufacturing Engineering Manager, David Lloyd.
"One stipulation was that the drives should be from Control Techniques, one of our two preferred suppliers - and our overall choice because of the drives' reliability and the back-up service we get from Control Techniques." "With the new machine we have achieved a substantial increase in cutting performance on the 10-25 mm diameter concentric service cable used by electricity companies." BICC also specified that, in order to achieve the higher productivity targets, the machine had to have single-operator manning, high winding speeds up to 250 metres/min, concurrent winding and an easy load/unload system requiring minimal labour.
All of these requirements were built into Meltech's design.
"We hadn't used Control Techniques drives very much before," says Meltech's, Andrew Proctor.
"There is a mix of different requirements on the machine and we were delighted to find that Unidrive covered all of the different modes, with the exception of the payoff drive, which needed a larger DC drive." "What's more, we had decided to use DeviceNet to simplify the communications and were pleased that the Unidrives were directly compatible with just the addition of a plug-in module." The Despatch Winder supplied to BICC has a PLC controller with touch-screen operator interface, a payoff stand and twin winding heads capable of taking plywood reels of up to 1,000-mm diameter.
Semi-automatic unloading of reels eliminates the operator having to handle the wound reels, with a discharge conveyor taking the reels to a pallet packing station.
The machine features automatic length measurement, pneumatic cable cutting and a precise servo-controlled traverse.
The payoff DC motor control is provided by a Control Techniques 75 amp Mentor II with a plug-in MD29 second processor unit.
Utilising an off-the-shelf Control Techniques winder program, that calculates required motor speed from line speed reference and a diameter calculator, Meltech modified the programming on the second processor.
With the easy-to-use drive programming language (DPL), a PID trim was added, based on a 0-10 volt error signal (5 volt set-point) from an analogue proximity sensor on a dancer arm.
In addition, Meltech wrote in an algorithm to alter the gain in the feedback and speed loops to compensate for the changes in dynamics of the drum - from as much as 2-3 tonnes when full, to only a few hundred kg when unwound.
DeviceNet connects five Unidrives, and additional remote I/O unit, to the PLC controller.
The payoff traverse drive is a 0.75kW Unidrive operating in open-loop mode for accurate unwinding of the payoff reel.
Two 7.5kW Unidrives operate in vector mode to provide the tight speed control, from zero to full speed, needed for the two winders.
Perfect match: A 0.75kW Unidrive coupled with a 2.8 Nm Unimotor controls the lead-screw mounted traversing head.
This solution provides the high dynamic performance and is digitally locked to the speed of the winder in use in order to maintain a constant pitch of winding.
The compact Unimotor brushless AC servomotor was the ideal choice for the limited space available.
Commutation and position feedback is provided by an incremental encoder that sends a signal back to the Unidrive, which has a second encoder module that sends the signal to the PLC for position control.
Unimotor is a new concept in brushless AC servomotors.
The new motors have been designed to supply high torque with either low or high rotor inertia.
Thermal performance is improved by the unique, new "finned" motor housing, manufactured in high strength alloy casting, which also permits accurate bearing to housing alignment and maintains air gap concentricity.
This optimises output and reduces cogging torque whilst the compact design gives increased torsional stiffness.
The final 0.75kW Unidrive, operating in open-loop, has the task of controlling a chain-conveyor to three positions behind the winders; winder 1, winder 2 or discharge position.
All the operator has to do at the touch-screen operator station is to select the plywood reel size, the speed of winding, the cable length required and the cable diameter.
He then puts a reel into the first winding point, secures the cable end, and presses 'start'.
The machine will then wind on the exact length and cut the cable.
The operator calls the winding head to the second position and repeats the procedure.
Whilst that is winding, he secures the cable end onto the wound reel and pushes it onto the chain-driven carriage conveyor at the back of the winding heads.
This then takes the reel to the discharge point where it is tipped and transferred by pneumatic grab onto a gravity-fed roller conveyor for moving onto the palletising conveyor for stacking, film wrapping and storage.
Up to 170 kilometres of cable can be rewound and cut and put into stock each week.
"We are so impressed with Unidrive that we are currently building a cable-winding line for an Australian customer using Unidrive and DeviceNet again," concludes Andrew Procter.
A final word from David Lloyd at BICC: "We are very satisfied with the machine.
Before we could wind about 50 reels in a shift.
Now we can wind up to 25 an hour! The savings will give us a payback in about 21 months and we are now in a position to respond much more quickly to customer needs." Meltch-Larmuth is a premier manufacturer of specialist winding machinery for applications ranging from all types of wire, cable and flexible extrusions through to aluminium tube and profile, steel strip, textile and plastic products.
The company also manufactures strand annealing furnaces and systems for the wire industry. Request a free brochure from Control Techniques ...
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