What to do if in the paper mill the arrival of a continuous machine is expected that will turn at 1,500 m / min? We need to prepare a suitable rewinder, capable of working 2,800 m / min. And, to close the circle, you also need a trimming suction plant just as powerful and efficient, able to dispose of at tips of 5,000 kilos of material per hour. Here's how all these pieces of an industrial puzzle have combined very well in a restructuring near the cutting of the ribbon
A continuous 900-ton paper machine a day. 2.800 meters per minute rewinder. A trimming suction plant can dispense tips of 5,000 kilograms per hour of material. These are the numbers that underline how much work is underway for the restructuring of the Villa Lagarina paper mill in Trento, purchased in 2005 by Pro-Gest and specialized in the production of paper for corrugators; At the center of everything is the new continuous recycled machine that is about to enter production and will be the fastest and most widely used machine in Italy. But it is interesting to see also what are the works and the contour plants in a project of this kind, which obviously must comply with the speed of the new continuous, 530 cm high, which will be 1,500 m / min. The most interesting plants among those already completed are represented by the Voith rewinder 85ML which will host the production of the continuous machine, tested last June, and the e cient suction plant designed and built by the New Aerodinamica of Casazza (BG), a company which over the years (it was founded three decades ago) has gained extensive experience in the paper industry, especially on fast rewinders with 2200/2500 m / min standards. But let's go in order, starting with the Pro-Gest group that has detected Villa Lagarina.
The group and the paper mill
Cartiere Villa Lagarina, this is the exact name of the company, represents the latest acquisition of the Pro-Gest group [www. pro-gestspa.it], founded in 1973 by Bruno Zago, composed of twelve companies with over 500 employees covering the entire production cycle from paper to packaging. The companies of the group are Corrugated Trevigiano (corrugated cardboard), Plurionda (special cardboard), Unioncart (die-cut boxes), Cartitalia (the first Pro-Gest paper mill), Cuboxal (pizza boxes), Carbonera paper mill (corrugating paper) ), Tolentino and San Giuliano (two other paper mills), Bergapack (corrugated packaging), Cartiera di Voghera and Cartiere Villa Lagarina.
As for the latter, it is a historic company, established at the end of the '60s by the Pesenti group and has a surface of 100,000 m2, of which about 40 thousand are covered. It has three tissue machines and a recycled machine, which is currently being finalized and replaces a continuous machine that is now exhausted. On the other hand, tissue machines are recently in place, with the last one being installed in 2002.
With the new continuous, capable of turning out paper from 70 to 120 grams, Villa Lagarina plans to reach an annual production of 300,000 tons. The works undertaken by Bruno Zago in the paper mill - which also include the upgrading of the purification plant (as regards the production of electricity the paper mill is totally independent) - required an investment of 80 million euros. The goal is to achieve a turnover of 100 million euros in 2009, compared to 55 million in 2006.
At the time of closing this article, in September, after the stop-and-go in August, more than 200 people worked at Villa Lagarina to complete the project for the new continuous and accessory plants. The mechanical and electrical assembly of the new Voith SpeedSizer, Post-Seccheria and Arrotulator were now at the nessage stage. The mixture preparation has been strongly modified and contains, among the various machines, also three huge disc lters for the thickening of the fibers.
The rewinder
Let's move on to the new 85ML rewinder by Voith Paper [www.voithpaper.com], already started, tested and ready to work on the future production of the continuum.
To house this 2.800 m / min machine, the paper mill has rebuilt a good part of the building with a healthy plant. Furthermore, in order to meet future production needs, a new shed has been erected in Villa Lagarina to house the nished product. Over 5,000 square meters of covered surfaces of 18 meters high, which will soon be equipped with a high-automation laser warehouse to give free rein to production.
The technologically very advanced 85ML rewinder was designed by Voith in collaboration with the Sao Paulo office in Brazil. The new machine, which replaces the aging 40-year-old rewinder Bruderhaus, is able to cut to nine sizes. The movement of the knives, the insertion and the bonding of the cores, as well as the expulsion of the nourished rolls, are all made by the machine in complete autonomy. This allows the operators to dedicate themselves to the quality of the cut and the re fi nishes. Once the coils have been unloaded, they enter into a robotic transport, wrapping, weighing and color labeling system. The multifunctional system, designed by Sicma in collaboration with the technical office of the paper mill, allows the reels to enter the warehouse with "a rather unusual harmony and perfection for a paper mill", as pointed out by Villa Lagarina.
The suction plant trims
Let's move on to the last ring, or the first in function of how we want to consider it, of the complex chain of plants that will lead to the new production capacity of Villa Lagarina: the suction plant. As mentioned, it was built by New Aerodinamica [www.newaerodinamica. com], a company from Casazza, in the province of Bergamo, operating for thirty years in the construction of plants for the recovery of processing waste in the most varied sectors. In these years it has been particularly specialized in the field of pneumatic transport and recovery with complete cycle plants realized from time to time according to the specific needs of the customers, using cutting-edge technologies that find particular application in the paper industry, paper binders , in the production of plastic materials and sheet metals. "Our experience", explains Paolo Radaelli of New Aerodinamica, "and the references in the paper sector, especially on fast rewinders, are increasingly increasing. We had started 30 years ago with a speed of 800 m / min to reach today speeds that can be said standard of 2200-2500 m / min. Last year we were contacted by Voith Paper for the construction of a suction plant with a new machine that would go into operation in the second half of 2008 ». New Aerodinamica would have therefore had to build a plant able to guarantee the intake of trimmings based on these initial characteristics: 2,800 meters per minute of machine speed, two trimmings with trimming width from 20 to 100 millimeters per side and weight from 90 to 150 gr / m2. The suction circuit had to be five meters, with two curves, while the pressing circuit had to be 40 meters, with five curves. "On the basis of these data", continues Radaelli, "we formulated our specific technical-commercial o er. I say specific because for us every plant is different from the others, every customer has his needs and problems and we try to solve them at best. In fact, it is unthinkable to offer everyone the same system, today we must give everyone their solution so as to fully satisfy their expectations ».
The installation in detail
But let's now go into the details of the installation, as it has been proposed, approved, installed. The first step was the choice of the necessary equipment, all original New Aerodynamics, resulting from the spreadsheet where the project data were inserted. New Aerodinamica proposed to install an aerodynamic polished stainless steel nozzle under each cutting unit and to connect them to two tearing fans, one for each, given the considerable speed of the machine and consequently a high quantity of material to be disposed of quickly ( maximum tip of about 5,000 kg / h). In order to have a constant suction of the inside of the nozzle, avoiding the "slamming of the same" at low speeds and also its breaking before cutting, a linear regulation system of the air flow to the nozzle was inserted. function of the speed of the machine.
The adjustment is carried out automatically and proportionally. «This system», explains Radaelli, «has been perfected and improved during the course of the last few years to be more and more reliable and precise». The aspirated trimmings are broken up by the two tearing fans positioned in the sub-machine and then transported by means of galvanized sheet pipes to an aerodynamic separator sized to discharge the trimmings inside the pulper without air. The conveyance of the reels into the pulper is carried out by means of a stainless steel slide complete with a washing ramp. The latter is used to insert pulp paste inside the hopper and use it as a transport, since there are about six or seven meters between the separator and the pulper. The separator outlet has been connected to a ltering group complete with head, body and dust collection hopper. These are drawn in, transported to the inside of the lter and deposited on the fabric-laden sleeves which are dropped into the collecting hopper by counter-washing tire shaking. A hopper is installed under this hopper, which with an iris seal system conveys and compacts the powder slightly and then bag it directly into sturdy transparent bags. These can also be replaced with the plant in operation, compared to the classic containers that you never know when they are full and then you have to pour them into bags with dispersion of the powders. The whole system is regulated and kept under vacuum by a high efficiency centrifugal fan which completely extracts all the air from the separator, creating a fall effect of the pipes as if it were snowing inside the drain. The installed lter complies with the D.M. 01/03 7/13943 and all the components comply with the current Machinery Directive. "The beginning of the assembly of our plant", concludes Radaelli, "started at the end of February 2008 and in mid-April 2008 we were able to carry out the blank test: measurements and calibration of the systems provided comparing the calculation data initially. The tests immediately gave positive results so the paper mill could start the production of paper. The maximum speed of 2800 m / min has been reached without problems ».
A good result
At Villa Lagarina they are very happy with how the works are going. "The installation of the rewinder", explains Francesco Zago, founder of the founder and recently joined the family business after finishing his studies in California, "is a consequence of the replacement of the continuous machine, an integral part of the restructuring project of the paper mill . In principle there were no significant problems, and in any case the installation did not preclude other work in progress, nor the production of the machine continues ». The plant, Zago continues, works well and the good are there: "While before we could only push ourselves to no 500 meters per minute, now we can reach 1,500 meters per minute with the machine continues, thanks to a rewinding speed of 2,800 meters per minute. The result is now achieved even if we have not yet reached the maximum production speed ".)