The new rapid service journal for calender from IRLE
Today paper machines are being operated like race cars - always at the limit and pit stops have to be minimized in their number and duration.
The new maintenance friendly roll journal helps to reduce downtimes in different ways:
- The design of the patented „Rapid Service Journal" separates the sealing function from the mechanical flow of the forces through the journal. Maintenance work on the roll does not require the dismantling of the whole journal. Removing the sealing unit will grant access to all components in the flow of the heating medium.
After re-assembly the roll will be ready for use. Time consuming rebalancing or regrinding is not necessary
- Apart from the technological qualities of the paper, i.e. the weight and moisture distribution the cross directional thickness profile of the sheet is determined by the load distribution in the Nip and subsequently by the geometrical shape of the thermal roll.
- Overhanging loads and different thermal expansion of roll body and journal have always caused problems at the paper edges. Especially with increasing roll temperatures this problem is not to be underestimated.
The solution for this is nothing new. The thermal edge insulation consists of an insulating pipe which drastically reduces the heat transfer in the edge area of the roll where no paper is running.
But what if the production mix requires different paper widths? With one fixed insulation width we would be back to square one. The proven technology of the edge insulation has therefore been further improved. The development of a variable edge insulation gives operators the advantage of being able to adjust the insulation width according to the web width. This can be done from the outside of the roll for all per-bores at once. The Rapid Service Journal can be equipped with this feature right from the start or retrofitted later on.
- While elastomeric seals can stand temperatures up to 285 degC with the new journal WALZEN IRLE uses special flat seals for temperatures up to 450 degC. This reduces the risk of leakages a lot.
- During operation of a calender roll elastic deformation transforms into plastic deformation. Fatigue causes stress reduction thus creating a runout. For re-balancing of the roll balancing weights can be adjusted at every position of the new journal design. Balancing is much easier and quicker than with conventional journal designs.
Due to the specialties of the material chilled cast iron rolls tend to bend under higher temperatures (bimetal effect). The new Rapid Service Journal is designed for an easy installation of flow reducer valves in certain per-bores in order to adjust the temperature in individual per-bores thus thermally straightening the roll.
Dipl.-Ing. L. Hellenthal / J. Knappe