Soft Calender Research Articles

Finite element analysis of the thermal bending of a chilled cast thermo roll

A previously-created roll model based on the ultrasound measurements of a chilled cast iron thermo roll of a soft calender was used to create a finite element (FE) model of the same roll. The FE analysis was used to simulate the behavior of the roll when heated and in changing operating conditions. The main interest was to study the thermal bending of the roll model. The simulated behavior was consistent with known behavior of the thermo rolls in general, and when compared to actual measurements carried out in the calender, the results of the simulation showed similar behavior between the roll model and the actual roll. The main difference was in the absolute value of the bending, but the bending directions were practically the same. These results are promising for future research to develop methods to avoid or minimize the negative effects of the thermal deformations in thermo rolls.

Effect of design and process parameters on nip width of soft calendering

ABSTRACTCalendering is a well-known operation in which a material is run between rolls to thin it into sheets or to produce smooth or glossy finish. An attempt has been made in this investigation to remove the drawbacks in the model of Meijers and applicable directly to soft calendering, also to make nip mechanics model generalized and applicable, so that it can be applicable where there is roll to roll or roll to plate contact. Also, the effect of various design and process parameters on results of soft calendering has been discussed using the data taken from paper industry.

Dynamic response of a cylinder cover under a moving load

Abstract Cylinders with thin covers are used in high-speed rolling contact industrial applications such as a two-cylinder soft calender of a paper machine. In this paper, the dynamic behavior of an elastic cylinder cover is studied using a 1D Pasternak-type foundation model with Kelvin–Voigt damping. The cover is subjected to a moving point load, which is taken to represent a load resultant due to rolling contact. Analytical expressions for the natural frequencies, vibration response, wave dispersion relation, total strain energy and dissipation power of the cover are obtained. To validate the 1D approach, the calculated natural frequencies and modes are compared to those given by a 2D plane strain finite element model, and a good agreement is found. The critical load speed at which traveling waves first appear in the cover is derived for the undamped analytical model on the basis of a resonance condition. The critical speed is shown to be also the minimum phase velocity of the waves in the cover. When damping is included, the wave speeds decrease, lowering also slightly the critical speed, which, in addition, becomes blurred due to the damping. Once a traveling wave has emerged, it remains in the cover also at supercritical speeds due to a spectrum of resonant speeds induced by wave dispersion. At supercritical speeds, reinforced resonances are observed when the head and tail of a traveling wave interact. High shear damping leads to a substantial increase in dissipation power related to heat generation and rolling resistance of the cover already at subcritical speeds.

Design of Hydraulic System for Soft Roll Calender

It introduces the working principles of the hydraulic system for soft roll calender, and designs the hydraulic system based on its technological requirements. Through the reasonable configuration of logic valve, solenoid proportional pressure reducing and relieving valve and so on, this hydraulic system can improve the working efficiency of the entire system, further improve smoothness of paper sheets, and improve the quality of paper.

The instance of operation of the High Temperature Induction Heated Jacket Roll for Paper Calender in Oversea Countries

Presently. the many paper mills have been calendering the paper & paperboard with the High Temperature Induction Heated Jacket Roll. called “Jacket Roll” in Japan.& Oversea Countries.Mainly. it is used for the Soft Calender & Hard Nip Calender under the high speeds at the high tetemperature. Because of recently, the many kinds of the paper & paperboard are requesting the good smoothness with bulk, good printability.& high gloss at the paper mills in the world.The paper & paperboard can be made the good quality by the Soft Calender & Hard Nip Calender with Jacket Roll under the lower nip pressure at the high temperature.In this report. just introduce the instance of operation by the High Temperature Induction Heated Jacket Roll for Soft Calender & Hard Nip Calender at the paper mills in the Oversea Countries.

On-Line Multinip Calender

The direction in calendering is towards on-line solutions, even with such higher value-added printingpapers as SC-grades and glossy coated papers.Soft calendering has enhanced the finishing of several grades, enabling quality which is better than with conventional machine calendering in hard nips, while at the same time simlifying the process by reducing the number of nips needed and employing simpler web runs. Still, there are limitations to soft calendering. Smoothness improvement is limited by relatively low nip pressures due to the wider nips associated with the large-diameter rolls used, and by the limited number of nips. On the other hand, off line supercalenders have continued to produce the highest quality capability. The biggest drawbacks to conventional supercalendering are the relatively slow speed, off-line operation and dependence on the use of filled rolls. These factors limit the production capacity and prevent supercalenders from meeting the challenge presented by faster paper machines.While advances in hot soft calendering and supercalendering have improved the state of calendering technology, there is a clear need for a new approach to calendering to produce SC-type grade, coated printing papers and similar value-added grades. That approach is OptiLoad.OptiLoad incorporates many innovative developments, such as Dura polymer-cover soft rolls and heated intermediate rolls. The top and bottom rolls are softcovered, zone-controlled Sym-Z rolls or multizone Sym CD rolls for effective caliper profiling. The OptiLoad principle makes it possible to fully relieve the total weight of each intermediate roll, utilizing lever arms and hydraulic relieving cylinders. Till now 18 off-line and 6 on-line OptiLoads including near future start-ups have already been sold in the world.

Study on Surface Smoothing of Magnetic Tape with Calendering.

With the evolution of magnetic tape to the Giga-byte level, smoother surface is required than before. The surface of the magnetic tape is smoothed in calendering process. It is necessary to estimate the surface roughness in the operation conditions of calender. This paper presents the analyzing method of the surface smoothing considering with the real contact area and the viscoelasticity of the magnetic layer at the temperature of calender roll. The calculated surface roughness is almost equal to experimental. However, in the case of soft calendering, calculated surface roughness is smaller than experimental. This is thought to be due to the visco-elastic deformation of the magnetic layer at the real temperature different from that of calender roll.

誘導発熱ジャケットロール 製紙における高温カレンダロールの展開

An induction heated jacket roll is regarded as an ideal heat roll, which gives uniform surface temperature with a good CD profile.Traditional heat rolls which use heated thermal medium produce uneven temperature profiles and cause higher temperature at the both ends of the rolls. This results in variation in a roll diameter CD profile and finally results in sheet thickness variation.The roll of this paper has an induction heat device inside and is jacketed like a heated pipe. With the combined effect by them, the temperature variation in a radial direction is compensated and the roll CD diameter profile is very well stabilized.Now, super soft calender rolls with a max. temperature of 360 degree C are successfully in operation.

Measurement of the pressure distribution in a soft calender nip

Measurement of the pressure distribution in a soft calender nip

印刷用紙のピグメント塗工とソフトカレンダ掛けについて

This paper presents results from pilot machine experiments together with production machine data on the use of film size presses for pigmentizing. Since the paper surface characteristics depend greatly on the type of calender used, some soft calendering results achieved with pigmentized paper are presented. The new equipment needed for manufacturing papers of this type is also described. It is shown that a modern film size press combined with a soft calender is a viable solution for grade improvement.

Ｎ‐１マシン ソフトカレンダーの操業経験

The paper machine N-1 of Yatsushiro Mill started up from November 1988 and has been operating successfully.This report describes the operating experience of Soft Calender from its start to now.

特殊合成樹脂製スーパーカレンダー及びオンマシンカレンダーロール ＩＩ 実機での使用結果

Following previous studies in which resins were evaluated on an experimental basis for applicability to supercalender rollers and on-machine soft calender rollers, the present paper describes conditions and results of plastic roller application in commercial paper mills. Plastic rollers are used for four types of soft-nip calenders, of which three are on-machine soft calenders and one is an off-machine soft calender. The on-machine soft calenders have been operating successfully and the off-machine soft calender has also been in smooth operation, although some initial problems were encountered. Although super-calenders have been operating favorably for thermosensitive paper, the application to the production of glassine paper is being tested. In addition, for other types of paper, only one or two rollers for multiroll super-calenders have been used, and applications are still being developed. The paper finishes by considering precautions to be taken when using plastic rollers.