WO2015044414A1

WO2015044414A1 - Disperger plate

Info

Publication number: WO2015044414A1
Application number: PCT/EP2014/070779
Authority: WO
Inventors: Vadim Gogichev
Original assignee: Philippe Saint Ger Ag
Priority date: 2013-09-30
Filing date: 2014-09-29
Publication date: 2015-04-02

Abstract

In a disperger plate comprising several concentric rows of a plurality of teeth, it is intended according to the invention that the surface of each tooth is an abrasive surface comprising abrasive material.

Description

Disperger plate

TECH NICAL FIELD

The invention is directed to a disperger plate comprising several concentric rows of a plurality of teeth.

PRIOR ART

A disperger is a specialized machine typically used in the paper industry for removing contaminants from recycled, or recovered, paper and packaging materials. The general configuration of a disperger has two circular discs facing each other with one disc being rotatable, the so-called rotor, and one disc being static, the so-called stator. On the faces of both discs exchangeable disperger plates are mounted. For easier handling several segments may form the disperger plates. Both the stator plate and the rotor plate have a plurality of concentric rings formed by several teeth on the surfaces of the two plates facing each other. The individual rings are spaced from each other and arranged such that the toothed rings of the stator plate intermesh with the toothed rings of the rotor plate. Thus, relative to the rotation of the discs each tooth has a leading surface, a trailing surface, two side surfaces and a top surface. The teeth are attached to or formed onto the plates with their base, which usually has a square or rectangular cross- section.

Typically the teeth are about 20 to 50 mm high. The length and width of the teeth is typically also in the range of 20 to 50 mm. The clearance between rotor and stator plates may be in the range of 0. 1 to several millimeters such that the fibers of the paper are not cut but rather severely bend by a kneading effect. Thereby contaminants are removed from the paper fibers. In some configurations the clearance between rotor and stator plates are adjustable by moving one of the discs in a direction along the rotational axis of the rotor. To adjust the clearance between the side surface of a toothed ring of the stator and the side surface of an adjacent toothed ring of the rotor, the individual teeth can have tapered side surfaces, such that the cross-section at the top is smaller than at the base. Such teeth usually have a pyramidal shape with a flat top surface (e.g. frustum or truncated pyramid) . Moving the two plates apart widens the clearance between the teeth.

For example, US5042726, DE1 0200904763 1 , E P2243879 describe several configurations of teeth with different shapes and orientations.

EXPLANATION OF THE INVENTION

So far dispergers have only been used in the paper industry for removing contaminants from recycled, or recovered, paper and packaging materials. It is an objective of the invention to provide a plate configuration for a disperger with good properties for defibrating wheat straw or the like for the production of molded product without the need of additional synthetic binders.

This is achieved by a disperger plate according to claim 1 . Thus according to the invention a disperger plate comprises several concentric rows of a plurality of teeth, where the surface of each teeth is an abrasive surface comprising abrasive material.

Straw particles, which are usually shredded to pieces of 20 to 50 mm before feeding to the disperger, are made of several fibres or bundles of fibres. Each fibre in turn includes several microfibrili made of cellulose. The abrasive surface of the teeth leads to a scratching action on the outermost layer of fibres and fiber bundles thereby increasing the active surface of the fibers by exposing fibrils and cellulose. The activated surface facilitates later bonding of the fibers when producing the molded products. In addition, due to the higher frictional forces when the straw particles are squeezed through the clearances between the teeth, the fibers are more efficiently torn apart and defibrated.

The abrasive material may be selected from the group of diamond, aluminum oxide, silicon carbide, tungsten carbide, cubic boron nitride, zirconia lumina, flint, emery, garnet and combinations thereof.

To produce the abrasive surface the entire teeth may be coated with the abrasive material or the teeth is at least partially made of bonded abrasive material.

In an embodiment of the invention each tooth has lateral surfaces and a top surface, the lateral surfaces being provided with several circumferential grooves or steps. The lateral surfaces may be defined by a leading surface, a trailing surface and two side surfaces. The groove or steps lead to an orientation of the fibers along the grooves or the steps. Thereby the fibers are guided along the abrasive surface of the teeth, which increases the scratching effect on the fibers or fiber bundles to activate their surface. The size of the grooves or steps may be 2 to 5 mm.

The lateral surface may be tapered towards the top surface such that the tooth has a pyramidal shape. In the case that the lateral surfaces are provided with several circumferential steps the tooth has the shape of a stepped pyramid with a flat top.

On each tooth having a leading surface, a trailing surface and two side surface the side surface may be tapered towards the leading surface, such that the width of the leading surface is smaller than the width of the trailing surface, preferably 1 -2 mm smaller.

The width of the teeth (distance between the side surface) may vary from the trailing surface towards the leading surface. The cross-section of the teeth being parallel to the disperger plate may be trapezoidal with the side edges tapered towards the leading edge. In such case the leading edge can be smaller than the trailing edge, preferably 1 -2 mm smaller. The leading edge may be straight or rounded. The cross-section may also have rounded side edges and a pointy leading edge.

The effect of the different cross-sections is that the clearance between the teeth of the stator plate and the rotor plate continuously changes during rotation of the plates to improve the kneading effect of the disperger. Another effect is that in combination with the grooves or steps the fibers being guided therein pressed more strongly onto the abrasive surface, when the clearance between the teeth narrows.

The above described form and structure of the teeth can also be subject of an independent invention without the abrasive surface.

BRIEF EXPLANATION OF TH E FIG URES

The invention is described in greater detail below with reference to embodiments that are illustrated in the figures. The figures show:

Fig. 1 a side view of a tooth; and

Fig. 2 two examples of a cross-section of the teeth along the line A-A of Fig.

1 .

EMBODIMENTS OF TH E INVENTION

Fig. 1 shows a side view of a teeth 1 arranged on a disperger plate 3. The teeth 1 has several circumferential steps 2 such that the teeth is in the shape of a stepped pyramid with a flat top surface 6.

Fig. 2 shows different cross-section of the teeth 1 along the line A-A of Fig. 1 . Under Fig. 2 (a) the cross-section has a trapezoidal shape with a leading edge 4 or leading surface smaller than the trailing edge or surface 5. Under Fig. 2 (b) the leading surface is rounded as compared to the flat leading surface of the teeth of Fig. 2 (a). Under Fig. 2 (c) the cross-section in the shape of a stepped pyramid with a flat top surface 6. The teeth 1 steps 2 of the teeth 1 The teeth has rounded side edges and a pointy leading edge 4 and looks more like a bullet.

Claims

1. A disperger plate comprising several concentric rows of a plurality of teeth, characterized in that the surface of each tooth is an abrasive surface comprising abrasive material.

2. A disperger plate according to claim 1 , characterized in that the abrasive material is selected from the group of diamond, aluminum oxide, silicon carbide, tungsten carbide, cubic boron nitride, zirconia lumina, flint, emery, garnet and combinations thereof.

3. A disperger plate according to claim 1 or 2 , characterized in that each tooth is coated with the abrasive material.

4. A disperger plate according to claim 1 or 2, characterized in that each tooth is at least partially of bonded abrasive material.

5. A disperger plate according to one of the preceding claims, characterized in that each tooth has lateral surfaces and a top surface, the lateral surfaces being provided with several circumferential grooves or steps.

6. A disperger plate according to one of the preceding claims, characterized in that each tooth has the shape of a stepped pyramid.

7. A disperger plate according to one of the preceding claims, characterized in that each tooth has a leading surface, a trailing surface and two side surface, the side surface being tapered towards the leading surface, such that the width of the leading surface is smaller than the width of the trailing surface, preferably 1 to 2 mm smaller.