The way in which tyres are sold to car dealers, garages, accessory shops and end customers has changed considerably over the last few years. Instead of large, palletised consignments, just-in-time delivery of smaller batches of tyres is now the fashion. But when this method of tyre delivery was still in its infancy, tyres were packed in large, expensive cartons that were easily damaged and awkward to handle, both during packaging and despatch. A more cost-effective and simpler method of packaging was therefore needed.
Packaging that did not completely enclose the tyres was immediately ruled out, because friction between units would have led to congestion on conveyor systems. The solution to this problem was film packaging, a method that could limit the cost of packaging material to as little as a tenth of a Euro for each wrapping. What’s more, tyres packaged in this way are easier to handle during packaging and despatch. As well as cost savings, film wrapping has other advantages: it protects against dust during storage and accessories such as tubes can be packed along with the tyres. The front side can also be labelled and different sized tyres can be packed together.
Frank Fährenkämper saw the market potential of film wrapping early on. He founded the Fährenkämper Entwicklungs und Vertriebsgesellschaft (FEV) in 1998, a company dedicated to developing special packaging machines. Today, FEV is one of Germany’s leading manufacturers of tyre packaging systems, taking a leading position by designing uncomplicated, competitively priced film wrapping machines to meet the needs of tyre dispatchers.
With the latest TE 1000 series wrapping machine, for example, the operator lays pairs of tyres on a roller table and positions them in the centre of a winding reel. When a foot switch is activated, the tyres are raised into position and the winding process begins. Motorised rollers, arranged in a star formation, spin the tyres in a horizontal plane around an adjustable angle, while the winding reel wraps approximately 1.5 layers of film around them every second. When winding is completed, the film is separated from the automatic film holder and cutter, and thermally sealed; the combined hub and rotation unit is lowered and the wrapped tyres removed from the front of the machine, or discharged to the rear by the next tyre.
The rollers used on this machine are rather special. Unlike conventional units, they do not need an external drive as they come with an integral 24Vdc motor. This motor, the secondary transmission and passive roller are all combined within a single, space-saving package, simplifying overall system design. The motorised rollers for this application - 50mm diameter EC200 RollerDrives - were supplied by Interroll. Originally designed for the zero line pressure conveyor market, they also include an integral control unit that can be connected directly to external control systems. Start, stop, direction of rotation and rotation speed are all controlled via two interfaces. An additional fault notification output enables these rollers to be directly connected to ICE IEC 61116.1 compliant control systems. Alternatively, the motor can be controlled via an external control unit (the Interroll DriveControl EC200/300 is recommended) with an eight level decode switch for speed control. This enables the electronic switch for start, stop and change of direction to be controlled with standard control equipment, giving the designer more flexibility.
When designing the winder FEV only needed to take the dimensions and position of the motor into account, along with the cable in the combined hub and winding table. Connecting the motor to the machine’s Siemens S7 controller proved quick and easy. Removing the RollerDrives for maintenance work is a similarly easy task– undo a single hexagon nut, disconnect the plug and that’s it. As well as offering integral electronic commutation and control, the EC200 units are also extremely quiet (<55dBA), and are barely audible to the machine operators. In this application, the motors drive through a gear reduction of 48:1, giving an operation speed of between 0.04 and 0.24m/s).
As previously mentioned, RollerDrives were originally designed for zero line pressure conveyor applications, for which Interroll offers complete kits. The kits provide motors, selected according to the needs of the application, as well as idlers, power connections and control electronics. Depending upon the type of power transmission required (rim-pull or form-fit, one or several idlers), RollerDrives are supplied with side heads that are compatible with V-belt, timing belt or chain drives. As an alternative, grooves can be pressed or machined into the roller casing itself.
RollerDrive facilitates a move away from central drive systems with complicated mechanics or pneumatics to a scheme of distributed, modular units of simple design that offers great flexibility when it comes to making changes to internal logistics. And should any of these modular units malfunction, it doesn’t mean the loss of the entire plant.
Drive rollers with integrated motors are also aesthetically appealing. They not only save space but compared with motors that are mounted either on the side or underneath the conveyor, they do not require any special clamps or fittings. Instead, they are integrated neatly in the roller tube. Apart from the cables, these assemblies can be treated just like idlers. Head of design and development at FEV, Andreas Brandl concludes:
“We are currently working on a fully automatic feed and discharge mechanism for our winder to relieve the burden on the machine operators and increase throughput. We can already see how RollerDrives would be an advantage here, especially the ideal match between idlers and drive rollers.”
Andreas Flies is key account manager at Interroll