For most people, conveyors are just a means of transport, but for Spiral Ventures and Wilfred Osula, its managing director, they are much more than that. They can provide “intelligent” solutions to the efficient movement of textiles round a laundry.
A customised system installed at Combined Linen Services,(CLS), Torquay, illustrates the truth of this philosophy.
To increase its productivity, the laundry was installing a new high-speed finishing line with a Kannegeisser PU11 sheet picker capable of handling up to 1000 sheets per hour. To realise this potential, CLS needed to automate the route from tunnel washer to ironer to supply the picker with a steady flow of work.
Spiral Ventures’ brief was to design a transport system from the tumblers up to the point where sheets were passed along to the picker. However, the brief presented severe logistics problems. The laundry handles three linen classifications which are washed in a strict cycle—six loads of table linen, six loads of sheets and one load of small items.
The transport system must distinguish between these classifications by providing two routes: one for sheets, the other for table linen and small items— which at this stage would be delivered to their ironing line by truck.
This had to be achieved within a confined space and still allow a gangway at the side. The two routes must therefore be incorporated within the same conveyor system.
From the laundry’s point of view, the sheet picker was a critical point in the line. A steady supply of sheets must be maintained, while bottlenecks must be avoided. At the same time, the flow of table linen and small items should not be disrupted.
Buffer storage for the sheets was therefore essential, but providing sufficient storage within the space available required considerable ingenuity, particularly as low ceilings ruled out the use of a monorail-based system.
In devising the solution, Spiral Ventures drew not only on its own expertise as the representative of Dutch conveyor manufacturer Vanriet, but also on the experience of two other companies, laundry equipment specialist Innovention and control experts, Micross Electronics.
To provide two different routes, Spiral Ventures designed a high-level conveyor crossed by a bi-directional conveyor at the far end. This bi-directional conveyor can be programmed either to send sheets on towards the picker, or to direct linen and small items to the other end where they could be discharged down a chute into a waiting truck. The system knows when a truck is waiting, as operators push a button to indicate that linen can safely be discharged. An alarm sounds if linen is waiting, but there is no truck.
Buffer
A floor-level conveyor with transfer carts runs parallel to the high-level route, and leads back up to the bi-directional conveyor at the far end.
The problem of fitting a buffer area into the limited space has been solved by installing a 10-bag motorised carousel between high-level and low-level conveyor equipment.
Electronically-controlled telescopic gates have been fitted into the high-level conveyor and sheets to be stored are directed through these into the bags below.
Spiral Ventures had worked with telescopic gates before, but the idea of directing sheets downwards into storage was developed in response to the situation. The company also devised the idea of using a carousel to maximise the limited space available and this was provided by Innovention. Each bag will hold a load of up to 50 kg, giving a total capacity of 500 kg.
The purpose-built, Micross PLC controller provides the system’s intelligence and keeps the flow of linen running smoothly. The controller communicates with the automatic picker to ensure a steady supply of sheets, either directly or from storage. The picker controls the telescopic gates in the high-level conveyor, so that they open to deliver sheets to storage, or remain shut when table linen and small items are being moved, or when sheets travel directly to the picker. The PLC controller switches the direction of the bi-directional conveyor.
It also programs the movement of bags on the carousel, making sure an empty bag is in place to receive sheets. When positioning bags, the controller will not only find the nearest bag, but also direct it by the shortest route.
The system has been in place now for nearly a year and CLS is achieving its productivity goals. Currently, three operators achieve a consistent rate of 900 to 940 sheets an hour and a fourth will soon bring this to 1000.
Tony Bozier, CLS general manager, is well aware of the difficulties the project at first presented and admits that there were some initial teething problems which Spiral Ventures was able to overcome. He sums up:”We threw them a problem and they solved it. The staff have been working comfortably with the system for nearly a year.”
