FI74065C - KALANDER, T.EX. SUPERKALANDER. - Google Patents

Description

74065

The present invention relates to a calender according to the preamble of claim 1, e.g. a supercalender.

Such calenders are used for polishing paper.

In previous solutions, the paper has been polished in machine fish blades by passing the paper web through nips formed by successive steel rollers, and the traditional supercalder blade consists of superimposed rollers between which the paper web is transported in an accordion-like manner. The rollers have been steel in machine calenders, while every second roll has been soft in supercalenders, which soft roll has been formed from cotton discs pressed tightly in the axial direction around a steel skeleton. The pressed roll is still turned into shape. The proportion of bone in the roll diameter has typically been 50-70¾. In the supercalender according to Figure 1, the paper web (1) is arranged to run accordion-like between the rollers (K, P). Auxiliary rollers (6) alongside the hard and soft rollers are used to adjust the paper web tension. Alternating, compressing hard (K) and soft (P) rollers provide soft; these nips allow fine finishing of the paper.

: In the prior art machine calender according to Fig. 2, the paper web (1) is arranged to pass through successive nips (3) of two pairs of rolls (K).

A steel calender does not give as good a polishing result as a supercalender. On the other hand, a supercalender is a remarkably expensive solution compared to a machine calender, and the soft roll is currently the most vulnerable part of the supercalender.

The object of the present invention is to obviate the disadvantages of the technique described above and to provide a completely new type of calender, e.g. a supercalender.

2 74065

The invention is based on the fact that a hard or soft roll is replaced by two, preferably hard rolls, around which an endless mat is arranged to rotate.

More specifically, the calender according to the invention ... is characterized by what is set forth in the characterizing part of claim 1.

The invention provides considerable advantages.

The most significant advantage is that, for example, the calender according to the invention has a supercalender polishing result which can be achieved at a reasonable cost. In the supercalender according to the invention, the mat is easy to change in order to change the quality of the paper surface. A damaged carpet can be sanded without removing it from the machine. In addition, the mat is more friable than the roll, which is why the pressure in the nip is more even than in previous solutions.

In the following, the invention will be examined in more detail by means of application examples according to the accompanying drawing figures 3-5.

Figure 3 shows a side view of the flow of a paper web in one supercalender according to the invention.

Figure 4 shows a side view of the flow of a paper web in one machine calender according to the invention.

Figure 5 shows a side view of the flow of a paper web in another machine calender according to the invention.

Figure 3 shows one implementation of the apparatus according to the invention. The paper web 1 is adapted to pass through a nip 3 formed by hard rolls 2 and 7, which nip 3 is soft due to a hard roll 7 and a mat 5 mounted around an auxiliary roll 4 arranged next to it. The auxiliary roll 4, the longitudinal axis of which is parallel to the longitudinal axes of the hard rollers 2, 7, is arranged on the opposite side of the auxiliary rollers 6 tightening the paper web 1. The mat 5 is some 3 74065 elastic material, e.g. rubber or plastic. The hard roll 2 is pressed against the mat 5, and since the rolls rotate freely, obtaining their driving force from the roll below through the nip 3 through friction, a speed difference is created between the rolls, due to which the surface of the paper 1 is polished. By varying the material of the mat 5, the length of the nip 3 and the pressure on the paper path 1 can be regulated.

Figure 4 shows one embodiment of a machine calender liquid according to the invention. In it, the second hard roll 2 of each pair of rolls in Fig. 2 is replaced by a combination consisting of an auxiliary roll 4, a soft mat 5 and a hard roll 7. Since these combinations are located on the same side of the paper web 1, a one-sided fine paper wedge is obtained.

The machine calender according to Fig. 5, on the other hand, achieves fine-sided finishing of the paper on both sides, because the roller mat combinations 2, 4, 5 are located on different sides of the paper web 1.

Within the scope of the invention, it is also possible to consider solutions that differ from the application examples described above. Thus, instead of one parallel auxiliary roll 4, it is conceivable to use two or more auxiliary rollers 4, whereby the endless mat 5 is arranged to run around all the auxiliary rollers.

Claims (3)

74065 A calender, e.g. a supercalender, having at least one soft nip (3) and comprising - at least two mutually weighing rollers (2, 7) between which the paper web (1) is arranged to run, and - a drive which rotates at least one of the rolls (2, 7) so that the other rollers (2, 7) are driven by friction via nips (3), characterized by - at least one combination (4, 5, 7) for producing a soft nip (3), which: consists of a hard roll ( 7), at least one auxiliary roll (4) parallel to this and an elastic endless mat (5) arranged around the hard roll (7) and each auxiliary roll (4). Calender according to Claim 1, e.g. supercalender, characterized in that each combination (4, 5, 7) is arranged only on one side of the paper web (1). Calender according to Claim 1, e.g. supercalender, characterized by at least two combinations (4, 5, 7) arranged on both sides of the paper web (1). I: