Locked Core Slitter Rewinder Manufacturer

The common types of rewinding methods include locked-core winding and differential winding. The locked-core method is a cost-effective solution for a wide range of converting industries, utilizing an air-expanding shaft to transmit a constant winding torque to all rolls. The differential method is much more complex and relatively expensive, differential controlled slip shafts have various designs to maintain equal tension on multiple rolls. Engineers from LEAP decide on the winding structure based on the specifications and properties of the coil materials.

Locked-core rewinding method
The cores are locked onto a winding shaft, and fixed by air expanding lug or strip. The linear velocity of web material on the winding shaft keeps synchronous with motor speed. The locked-core method is widely used for rolls with large diameters and large widths, especially appropriate for rewinding a full-width roll without slitting. It’s frequently applied on a surface winder where the rewinding shaft isn’t driven from its center. Mechanical lug shafts are designed with powerful expansion mechanism, and provide great gripping force on cores to handle heavy roll weights at high speeds, it has many advantages of high efficiency, simple structure, low cost, convenient unloading, etc.

However, the locked-core winding manner has many limitations for some materials which are easily damaged when stretched. In the winding process, it’s difficult to guarantee all the rolls have the same diameter due to the accumulation of web thickness error, which means some rolls may wind too loose and some rolls may wind too tight. This difference can result in various quality issues including roll telescoping, broken, starring, weaving, crushed wraps, etc. Besides, the quantity of winding rolls is another factor. Generally, the more rolls being wound on the winder, the greater the error is obtained. When this inconsistency exceeds the acceptable level, the coils can not even be reeled.

Differential rewinding method
Differential air shafts can help you to maintain equal tension on multipul rolls. Cores are gripped by friction rings which run on a central shaft, individual rewinding rolls aren’t completely locked onto the winding shaft and they are allowed to slip relative to one another, the tension ranges of the shafts are adjustable by changing the expanding strip material of the centre shaft which offers the slippage. This is known as "differential winding". Each wound roll is driven from its center at a different speed to maintain a consistent outer surface speed. This method can help each independent roll run at appropriate speed and tension and realizes high-quality rewinding of web materials which have non-uniform gauge by varying the torque applied to the core. Differential rewinding technology is commonly utilized in applications of center-winding slitter rewinders.