Precision ring track simplifies turret mechanism
09 June 2013
An off-the-shelf ring track system allowed a label converting and finishing machinery manufacturer to create a more cost efficient mechanism for its new turret rewinder module.
The precision ring track system replaced a complex centre shaft arrangement to carry the turret disc, simplifying the mechanism and introducing other design advantages into the bargain.
A B Graphic is a market leader in fully modular digital converting, inspection and turret rewinding. The company also produces machines for specialist applications, including RFID insertion, laser die cutting, booklet labelling and camera inspection. The machine range for which the turret rewinder was developed is A B Graphic’s Digicon Series 2, featuring a modular construction that allows each machine to be custom built.
One of the options that customers can specify for this machine is a turret that facilitates non-stop rewinding of label rolls at the end of the finishing processes. It automatically cuts the material and re-applies it to the new rewind mandrel. As roll changing is automatic, maximum productivity is assured. And as the finishing processes run continuously, waste is virtually eliminated.
An off-the-shelf ring track system – HepcoMotion’s PRT2 - carries two mandrels that are mounted on the ring. When one mandrel is full, the turret rotates 180 degrees so the next mandrel can be rewound. A B Graphic specified its PRT2 with a gear cut option as this provides an easy means of achieving a positive and rigid direct drive via the circumference of the turret disc. A B Graphic design engineer, Mike Adams takes up the story:
“On the forerunner of this rewinding system, we used a belt drive to the centre shaft which created a less positive drive. The drive needs to be as positive as possible as movement can create web tension variations when indexing. The new mechanism also required less structural support and mounting the turret disc accurately to the machine face plate is easier too.”
Another useful benefit of the PRT2 is the fact that it leaves a hollow centre, which accommodates the rewind drive input and air supply to the mandrels. The previous centre shaft arrangement could not provide such a neat design solution.
Dewsbury-based machine builder, Techserv Cutting Systems is another convert to HepcoMotion’s PRT2. The company supplies gas, plasma and waterjet CNC cutters offering cut areas of up to 6m wide by 25m long with multiple tool options. These machines feature automatic three-torch rotating bevel heads for weld preparation – a useful tool for setting the bevel angles when cutting thicker materials.
This is where the PRT2 comes in useful. The friction-free, debris-tolerant system combines ring segments and straight slides to achieve an almost limitless variation of open paths and closed circuits. The advantage PRT2 offers is that the end point of the torch is at the centre point of the ring section, so the bevel angle for weld preparation can be set at the control panel by a simple twist of a knob.
Techserv also finds uses for HepcoMotion’s GV3 linear motion system. This provides a ready-machined surface for component assembly, and gives Techserv a lead-time advantage when meeting urgent customer orders. Techserv uses an aluminium extrusion in combination with the GV3 system to achieve the desired repeatability. The GV3’s all-steel slideway is three times stiffer than composite aluminium systems.
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