Tissue paper is a material that requires special precautions both during production and in the operations carried out in the so-called end of line. During rewinding it is in fact essential to maintain the creping and density of the Tissue obtained in the upstream process in order to preserve its distinctive softness and bulkiness.
To achieve this goal, a series of specific measures must be implemented, such as avoiding excessive pressure on the reel, precisely controlling the elongation of the sheet to maintain its creping as much as possible or using adequate values of nip load.
Solutions for the iDEAL® tissue winders
The pope reels in the iDEAL® product range offered by A.Celli are equipped with solutions specially developed to preserve the properties of tissue, including:
ROLL WINDING CONTROL
A system that is applied on the secondary arms of the pope reel to keep the nip load between the roll and the reel drum at the minimum value necessary for correct winding as the diameter of the roll varies, thus preserving the softness of the tissue paper.
The secondary arms are equipped with specific linear position transducers and are operated by hydraulic or pneumatic cylinders, controlled in turn by servo valves and pressure transducers.
A control system regulates the thrust applied by the arms to the winding shaft, automatically modulating it during the winding process. At the same time, the system controls the shape of the roll being wound, keeping it perfectly cylindrical and free of defects.
CENTER WIND ASSIST (CWA) SYSTEM
This system consists of a motor, managed by the sectional machine control and mounted on the end of the shaft, capable of transferring drive torque directly to the roll being wound. In this way the torque that must be transmitted through the nip is reduced, eliminating the need for a high nip load value which would lead to a crushing of the sheet, with obvious consequences on its softness and bulkiness.
Like the previous one, the CWA system is also typically applied to the secondary arms of the pope reel, where most of the roll formation takes place, but it can also be applied to the primary arms to optimize the winding quality from the first turns.
Solutions for the E-WIND® tissue rewinders
The range of A.Celli E-WIND® rewinders dedicated to the processing of Tissue paper includes machines with proven quality and reliability equipped with solutions specifically developed to preserve the bulk and softness of the tissue even during this delicate phase. Let’s see them in detail, dividing them by section of the machine on which they are installed.
TENSION CONTROL DURING ROLL UNWINDING
A control that allows automatic adjustment of the sheet tension, keeping it at the minimum values necessary for the process requirements and thus avoiding transmitting excessive stresses to the reel that can affect the creping. The tension is measured continuously by means of a pair of load cells mounted on a specially designed and positioned guide rollers.
In case of multiple unwinders, it is advisable to install the control unit on each of them in order to individually control the response of each reel, thus maximizing the final result.
In the unwinders, the rotary unwinding motion imparted by the driven belts to the outermost coil of the reels is harmful to the properties of the tissue paper, which is by its nature not very resistant to mechanical stress.
The axial control consists in mounting an electric motor at the end of the shaft. This motor is controlled by the sectional control through the continuous measurement of the reel diameter, with optical sensors capable of determining the correct instantaneous angular velocity. By doing so, it will be possible to impart motion to the reel by acting directly on the shaft, without affecting the paper with any mechanical interaction capable of altering its characteristics.
This solution involves the expandable shaft and allows to relieve the reel being wound of a part of its own weight, in order to avoid the crushing of the product and thus preserving its bulk. For this purpose, the load on the shaft determined by the aforementioned reel is constantly measured by a pair of load cells located on the spindles. The data collected are then transmitted to the control system, which regulates the lightening pressure according to a curve determined by the operator.
RIDER ROLL RELIEVING
The rider roll has the task of stabilizing the finished reel in position during its winding. In order to preserve the softness of the product and avoid its crushing during the process, we install two load cells on the two ends of the rider roll. These load cells have the purpose of sending a signal to a special control system which, consequently, regulates the value of the load that the rider roll exerts on the reel during the rewinding phase, thus preserving the characteristics of the product.
LARGER DIAMETER SHAFTS
Thanks to the use of larger and more robust diameter shafts, it is possible to increase the lightening force towards the finished reel during rewinding, thus improving the effectiveness of the shafts themselves in terms of maintaining bulk and softness of the tissue paper.
A consultative approach to offer you the best solution
In addition to the solutions listed above, to obtain optimal results during tissue paper processing it is advisable to use machinery built according to the specific needs of each company. This is why A.Celli is able to offer you customized solutions for an optimal management of bulky tissue paper with high crepe ratios, whatever your production needs are.