Getting to grips

Rewind shafts boost productivity

A recent machine to exploit the benefits of Parkland International's air differential rewind shafts is an SM150 Series II slitter rewinder delivered to Autotype International, in Wantage, UK.

Autotype's products include coated films and laminates from 50-750 micron thick, used for touchscreens, LCD displays and control panels. Maximum material width is 1,500mm with a minimum slit width requirement of 50mm at running speeds of 300m/min. The Parkland shafts are said to give precise and individual control to each slit width. On this particular machine, cores are gripped by ball type self expanding torque chucks, but roller chucks are also available.

Production is carried out in cleanroom conditions placing particular demands on the machinery. Differential control with the Parkland shafts relies on slippage on the inside of each chuck, said to eliminate the friction wear and potential dust hazard associated with other designs that rely on movement between the inside of the core and the shaft.

Cores used with these shafts have to be specially made and this affects production costs. Also, core spacers are often required to maintain side location. The Parkland design is said to offer a much simpler and cost effective solution.

The cantilevered shaft design of the Autotype machine works in association with a powered push-off mechanism for easier unloading of slit reels. The result is said to be faster turnround and reduced downtime, particularly important with small runs.

The push-off mechanism consists of a screw driven plate. Once the shaft support door is swung clear, it traverses the machine, pushing against the rewind cores to transfer slit reels onto the spindles of a motorized turret off-load system, which engages with the end of the cantilevered shafts.

Laser core positioning and digital knife setting are also used to speed and simplify change-overs. Separate DC motor drives to each rewind shaft give the option of clockwise and anti clockwise rotation.

Maintenance made easier

New shafts from Schlumpf include the DuoGrip, a lightweight model with an extruded aluminium body. Designed for minimum maintenance, all of its components are accessible from the outside – without having to remove shaft journals.

Also new is the FlexGrip – claimed to provide flexibility for clamping large diameter cores. The standardized clamping system and its components - bladders and segments - will fit any large diameter shaft body of an appropriate wall thickness.

A new mechanical winding shaft, the Type –SF is actuated by spring force, said to provide a high degree of safety, with retraction activated by compressed air through integrated piston plates. This shaft can be supplied in all sizes from 76mm upwards and is said to offer high reel concentricity for high speed webs and delicate materials. Schlumpf says it is also ideal for operation in vacuum-like conditions.

On the chuck front, the company's QuickGrip range of modular mechanical self-centring cores is offered for light to medium shaftless applications. The QuickGrip expands concentrically by rotating only a few degrees. It rotates in both directions and requires neither compressed air nor hydraulics.

The unit is also said to benefit from Schlumpf's Easy-Care concept - a facility that allows partial disassembly of the chuck in seconds for cleaning and maintenance - without removing it from the machine.

Better than board

Made from a robust grade of recycled HDPE, the Coba Plastics range of cores are said to be strong, water resistant and suitable for repeated use over long periods - unlike conventional board.

Their construction provides far greater resistance to end damage, Coba points out, giving operators increased efficiencies on loading and unloading mandrels and other slitting rewinding equipment. Storage benefits are also claimed, as plastics cores are resistant to water ingress, while retaining tight control dimensions on internal and external diameter.

Plastics cores can also be slit down by the customer without swarf or dust affecting the final product.

Leaves that lock

Webtek recently introduced a patented pneumatic adapter chuck for high torque applications. The new chuck, from Taiwan based manufacturer Minply, has gripping elements that are extruded aluminium leaves with a specially machined surface and polymer segments. These are said to ensure a positive grip, eliminating the possibility of slippage, particularly in high torque applications. The chuck is available to suit most common core sizes.

Another addition to the Webtek range of core chucks is the TP600 core insert plug - introduced specifically for the tissue converting market, where the use of large diameter cores is commonplace. The TP600 is said to offer a lighter weight, single piece alternative for manageable manhandling.

Risk reduced by rubber

A major UK slitter manufacturer recently took delivery of two large Rimor knife shafts complete with bottom knife blocks for paper slitting application. Both shafts are over 3.4m in length and have an outside diameter of 360mm.

Rimor used continuous rubber type lugs with built-in rubber return springs to allow gripping of the multi knife blocks. The company says this system eliminates metal return springs, which could break and puncture the bladder. The 12 gripping lugs situated around the circumference of the shaft enable the knife blocks to be positioned securely and accurately. The expanding bladders for the grippers also utilize a small volume of air to allow quick inflation and deflation.

The shaft had to be accurately ground and chrome plated to allow the knives to be easily adjusted by means of a automatic positioning system supplied with the slitter.

Cores score a big order

UK supplier of precision moulded plastics cores Fibrebond has secured its most significant order yet, from "one of the largest tape converters in the business", who has placed a one year contract for the supply of 3in close tolerance cores.

Fibrebond is branding this part of its business with the name tapecentres.com, to maximize sales across Europe with a website presence. The company says this has recently proved successful in landing a core supply order from the Czech Republic.