SU1606562A1 - Press for dehydrating fibrous material web - Google Patents

Abstract

The invention relates to the design of the press section of a paper machine and may find application in the paper industry. The purpose of the invention is to intensify the dewatering process by extending the extrusion zone. The press consists of a bed 1, shafts 2 with a wave-like surface, installed in such a way that the convex and concave surface areas of one shaft coincide with the concave and convex surface areas of the other shaft. Between the cloths 3 and 4, the wet cloth is transported to the grip between the rotating shafts, where it is pressed and dehydrated. The concave surface areas of each shaft have a radius of curvature that is 1.8-2.0 times the radius of curvature of the convex sections, which leads to an intensification of the dewatering process. 1 hp ff, 5 ill.

Description

FIG. ,

The invention relates to the pulp and paper industry and can be used in 6yfytaro and cardboard machines for pressing pulp, paper and cardboard.

The aim of the invention is to intensify the dewatering process by lengthening the pressing zone.

Figure 1 shows the press, a general view; 2-5 show the engagement geometry of the pressing rolls,

The press consists of a bed 1, the upper and lower shafts 2, having a wavy working surface. The shafts are synchronized with the drive and are covered from the outside by endless cloths 3, 4..

The press works as follows.

The shafts 2, installed in such a way that the convex and concave portions of the upper shaft profile in the pressing zone coincide with the concave and convex portions of the lower shaft profile 2, are simultaneously rotated. At the same time, the covering shafts of cloth 3 and 4 are set in motion. The wet cloth is fed between the cloth and transported by them into the grip between shafts 2, where it is pressed and drained. The water, pressed from the web in the pressing zone, is absorbed by the felt and removed with the web from the press zone.

Fig. 2 shows the profile of the wavy surface of the shaft, in which the ratio of the radii of curvature of the concave and convex

loose surface areas

Jr

Rl.

is

in the range of 2.0 - 1.8. The lengths of the ADBi and BiDtC arcs are the same, and at the place of their intersection (point BI) they have a common tangent MN,

Fig. 3 shows two different positions of the wavy surface of the shaft, the initial position 1 and position 2, which the surface takes when the shaft is rotated in a clockwise direction. The value h shows how much the cloth 4 oscillates on, covering the shaft and the drive roller when the position of the wavy surface changes as the shaft rotates. 50

Fig. 4 shows the pressing zone at different positions of the contacting surfaces. Since the length of the BiC and KB arc is the same, when rolling the CB arc along the BiC arc (position 1), the end 55 points of the arcs C and B coincide. At this moment (position 2) there is a transition from you-and the convex surface to concave on one shaft (from KB and BK1) and, on the contrary, on the other

shaft (from BiC to CB2), since the arcs of BiC and KB in the point of conjugation (C) with arcs of CBA and BK1 have a common tangent (the radii of curvature of curvilinear surfaces lie on one straight line passing through point C), then replacing CBA and BCT arcs on symmetric CB2 and BK1 arcs, we obtain the geometry of the pressing zone, similar to the geometry in position 1. Thus, the geometry, and consequently, the size of the pressing zone, is the same in both cases.

Figure 5 shows, for comparison, the size of the press zone in the gripper of the round shafts and shafts 2 with a wavy surface.

The table shows the effect of the ratio of the radii of curvature of the wavy surface of the shaft to the size of the extrusion zone and the amplitude of the oscillation surrounding the shaft.

As can be seen, with an increase in the ratio

R

The radii of curvature -5- of the concave and convex surface areas forming the grip decrease the size of the extrusion area. So, with the ratio R

equal to 1.24, the extrusion zone compositionR

It is 98 mm, and at a ratio equal to

KI

2.8-64 mm. The size of the compressed zone for round shafts with a radius of 400 mm (which is the main one for shafts with a wavy

surface) is 53 mm.

p With a decrease in the ratio

RI

behind

by increasing the wavelength of the side surface, an increase in the oscillation range of the felt, which is located

the lateral surface of the vrash, the shaft.

P For example, at a ratio equal to

1.24, it reaches 32.5 mm. This may be caused by a break in the paper, cardboard cloth transported by the cloth, since with a swing of the cloth exceeding 30 mm, it is possible to separate the cloth from the cloth.

The use of a wavy surface, in which the concave and convex portions are arcs of the same length, having a common tangent at the interface, provides, at different positions of the contacting surfaces, the same pressing zone, which is the main condition for the possibility of using shafts with a wavy surface to expand zones of pressing and pressing of paper, cardboard cloth without reducing its quality.

Using a wavy surface,: in which the concave portions are formed by a large radius of curvature R. and the convex ones are smaller RI, and the ratio of these radii

-sch- equal to 2.0-1.8, provides an increase in the area of pressing by 40-50% compared to the area of pressing for round shaf08 of the same damztra and the allowable 15-25 m | m oscillation rate of paper and paper density during running and gathering from shafts. Thus, the proposed press provides, in comparison with the known, an expansion of the pressing zone by no less than 1.5 times and a relative increase in the dryness of the web after the press by 10-15%, and a uniform pressing of the web over the entire area.

Claims (2)

1. A press for dewatering a fibrous material web containing dtanin and two shaft covered with fells with a wavy working surface, the convex portions of one of which are opposed to the concave portions of the other, which is characterized in that, in order to intensify the dehydration process by extending the extrusion zone The concave portions of the working surface of each shaft have a radius of curvature that is 1.8-2.0 times the radius of curvature of the convex portions. 2. A press according to claim 1, characterized in that the lengths of the arcs of the convex portions are equal to the lengths of the arcs of the concave portions. FIG. g and N ABOUT , ffojJOfKGHue i Canvas Hue 2 Fig.Z Position i Position 2 FIG. liH Ki FIG. five