Pneumatic expanding shafts
Expanding shafts are used to unwind and rewind rolls and reels of any material. TRASCO's technical team can design expanding shafts in different materials according to customer requirements, such as aluminium, high-capacity steel, carbon fibre, and ultra-light solutions.
Journals can be made in different types of steel and undergo any type of surface treatment.
TRASCO can provide customers with a range of solutions.
This represents the most innovative technology on the market, suitable for any type of application.
Each strip is powered by the corresponding air chamber, which ensures its expansion.
Maintenance operations are quick and easy, and do not require the journals to be removed.
TRASCO has more than 20 extruded aluminium profiles set up for strip assembly. These profiles suit any requirement, and range from a minimum diameter of 48.5 mm (2") up to a maximum diameter of 198 mm (8").
Numerous solutions are available in terms of expanding shaft weight, maximum applicable load, number and width of continuous strips, or maximum torque that can be transmitted to reels.
If required, TRASCO can design and produce special steel shafts with high load capacity, of any diameter and length.
Diverse surface treatments can be applied on the basis of specific application requirements.
TRASCO is also the only company in the world to provide expanding shafts in carbon fibre with expanding strips. The strips can be made of aluminium, rubber or Polyzene (polyethylene PE 500) on the basis of specific application requirements.
Solution designed and implemented to ensure higher concentricity between the expanding shaft and the reel.
The standard version, involving expansion with continuous strips, uses just one air inlet valve. After passing through the valve, the air is free to circulate inside the various air chambers.
In the standard model, during rotating motion a small amount of air exits the chamber undergoing more strain from the weight of the reel, and this increases the pressure inside the remaining chambers. As a result, shaft-reel concentricity decreases.
In the case of expanding shafts with continuous strips and separate air chambers, each air chamber has its own inlet valve. This means that after passing through one of the valves, the air remains confined to its chamber. This particular solution increases concentricity between the shaft and the reel considerably.
The model with separate air chambers prevents communication between the various chambers i.e. air passing from one chamber to another. Concentricity is therefore excellently maintained despite the weight of the reel.
This particular solution virtually eliminates the possibility of periods of inactivity. The separate air chambers ensure operation of the expanding shaft, even if a chamber is compromised, and make maintenance operations much quicker.
This technology is available with any expanding shaft produced by TRASCO, be it in aluminium, steel or carbon fibre.
The expanding shafts with strips and self-centring facilitate better concentricity between the shaft and the reel, as in the case of expanding shafts with separate air chambers. The expansion of the strips is split into two different phases.
PHASE 1 - The first phase involves the expansion of half of the strips. These expand until they reach a diameter D1 which is not much bigger than the internal diameter of the core, ensuring the shaft is centred with respect to the reel.
PHASE 2 - This second phase takes place immediately after the first one, thanks to a special pneumatic supply system. The remaining strips, defined as clamping strips, expand to a diameter D2, which is larger than D1. The internal core of the reel, which is appropriately positioned around the shaft during PHASE 1, is attached at this stage and rotated while maintaining the correct concentricity.
The self-centring system is available on any expanding shaft produced by TRASCO which has at least 6 continuous strips, be it in aluminium, steel or carbon fibre.
Expanding shafts with continuous strips and axial adjustment are ideal for optimally centring reels for cantilever shafts during material winding/unwinding operations.
This type of shaft has a central body, on which a profile with expansion elements is fitted, which enables axial movement via a front knob adjustment system.
Reels can be adjusted during the work cycle (with the machine in motion), and without stopping the process.
These shafts can have strips in rubber, aluminium or Polyzene (polyethylene PE 500), with journals made according to customer specifications.
Expanding shafts with keys are used when the continuous strip solution cannot transmit the required torque.
Expansion occurs through one central air chamber. The body of the shaft can be made of aluminium, steel or carbon fibre, depending on the intended application and the weight of the reel. The keys are available in aluminium or hard rubber.
The central air chamber, situated inside the expanding shaft, has a special clamping system that simplifies its replacement. However, maintenance operations in general are more complicated compared with expanding shafts with continuous strips, as they require the journals to be removed and the keys to be reconnected if the air chamber has to be replaced.
This type of shaft is used when the core of the reel is especially thin. In such cases, expansion via leaves / ledges redistributes the pressure, which avoids deformation by acting on the material uniformly.
The body of the shaft is usually made of steel. The leaves / ledges are made of steel or aluminium, depending on the application parameters. Longitudinal or knurled (criss-cross) milling is carried out on them, depending on grip requirements.
If material winding/unwinding operations do not require the use of cores, Trasco can provide a special leaf / ledge solution in the form of gripper coreless shafts.
Friction shafts (ASA differential shafts) are used to wind one or more reels separately.
This type of shaft has a central steel body on which friction rings are fitted, measuring 9 to 59 mm in width depending on the reels to be wound.
Self-expanding spheres are fitted in one or more rows on these rings, depending on the width and range required.
The spheres lock and release the cardboard cores by means of continually regulating the air via a rotating joint. The strips fitted to the central body can be made of different materials, depending on the application and range required.
Independent friction rings allow to keep the needed web tension constant, even with different roll diameters and material thicknesses.
