WO1997022449A1

WO1997022449A1 - Chipper for oversized chips

Info

Publication number: WO1997022449A1
Application number: PCT/SE1995/001529
Authority: WO
Inventors: Gustav Fredriksson
Original assignee: Rotom Verkstäder Ab
Priority date: 1994-06-23
Filing date: 1995-12-18
Publication date: 1997-06-26

Abstract

A chipper (1) intended for oversized chips comprises a housing (2) having an inlet (3) of the material to be chipped, an outlet (4) of the chipped material, a rotatable splitting drum (5) within the housing (2), the drum being rotatable about a substantially horizontal axis (6) and provided at its circumferential surface with chipper knives (7) and a counter knife (8) fixed inside the housing (2). The inlet (3) opens into the splitting drum (5) in such a manner, that the material fed into the splitting drum hits the splitting drum (5) at a position, in which the drum moves upwards in its rotation.

Description

CHIPPER FOR OVERSIZED CHIPS

The present invention relates to splitting machines, particularly to a chipper intended to split screened-out oversized pulp chips.

The screened-out, oversized pulp chips substantially comprise overlong chip portions, such as slivers and surface-wood shivers as well as overthick dimensions. In order to minimize the rejects, it is thus desirable to be able to split this kind of material, primarily through cutting the pieces lengthwise but also, when needed, through reducing the thickness of the pieces. In connection with this, it is also desirable to prevent the formation of shingle and pin chips.

In splitting the chips longitudinally, *and when the thin splinters of surface wood, it has previously been tried to achieve an orientated feeding of the chips at right angle to the cutting edges or knives of the splitting equipment. This has resulted in the undesired formation of great quantities of chips and pin chips. Since the previous techniques permit oversized, particularly long and thin pieces to pass out of the splitting machine, this, in turn, has necessitated re-screening of the material flow.

The previously known splitting machines further presents drawbacks, such as a high level of noise and heavy generation of dust, giving rise to problems with respect to the working environment, and they are further affected by wear and are easily worn-out by sand and metallic objects, which are virtually always entrained with the fed chips, at least to a small extent.

The purpose of the present invention is to eliminate the above- stated problems. This purpose is met with a chipper for overlong chips of the type set-forth in the claims, which also indicate the characterizing features of the invention. The invention will now be described with reference to the appended drawings, wherein:

Fig. 1 is a diagrammatic sectional view through a chipper of the invention;

Fig. 2 is a broken-away, enlarged sectional view of a cutting edge and its mounting to the splitting drum; and

Fig. 3 is an enlarged, sectional view taken through the circle designated by Q in fig. 1.

The splitting machine or chipper 1 for oversized chips of fig. 1 comprises a housing 2 having an inlet 3 for material to be split or chipped, and an outlet 4 for the chipped material. Within the housing 2, there is provided a rotatable splitting rotor 5 supported by a shaft 6. The inlet 3 is open towards splitting drum 5 all the way to its top point. The outlet 4 is located adjacent to the bottom of the housing 2.

The splitting drum 5 comprises a set of knives 7 placed in successive rows which extend in parallel to the axis 6 of rotation. Each row in its turn comprises knives 7 which are placed side by side and spaced apart by a distance. A counter knife 8 is placed at the top of the housing 2 at a point, where the splitting drum 5 has its top point. This counter knife is cam-shaped, meaning that the knives 7 will pass through the recesses thereof, while the protruding parts will project towards the spacings between the knives 7. An axially extending, open groove 10 is provided between each knife holder 9 and the subsequent knife 7. Although the counter knife preferably is located as shown, i.e. at the top point of the drum 5, other locations, such as in front of and behind this point, will be possible within a range of about 20° in each direction from this point. The inlet opening 3 is designed to permit material which is fed therethrough to hit the splitting drum 5 in the area preceding the cam-shaped counter knife 8, i.e. where the drum 5 in its rotation is moving upwards. It has been found that this design results in the elongate chip fragments and pin chips being orientated into the grooves 10 before reaching the counter knife 8. The material within the grooves 10 will be split into sizes corresponding to the width of the knives 7, without formation of any significant quantities of shingle and pin chips. This eliminates the need for post-screening of the material. Further¬ more, guiding of the fed material to the chipper in order to suitably orient the material will not be needed.

The chipped pieces then are thrown towards the adjacent wall of the housing by means of the centrifugal force of the splitting drum 5, from which wall it falls down through the outlet 4 of the bottom of the housing 2. Any pieces that for any reason may be jammed within the drum 5 will be subjected to subsequent machining in passing the counter knife a second time and will then generally fall out without any problem.

Through the present invention, there has been provided a simple an efficient solution to the initially presented problems.

Claims

PATENT CLAIMS

1. A chipper (1) oversized chips, comprising a housing (2) having an inlet (3) of material to be chipped, an outlet (4) of the chipped material, a rotatable splitting drum (5) within the housing, rotating about a substantially horizontal axis (6) and provided at its circumferential surface with chipper knives (7), and a counter knife (8) fixed inside the housing (2), character¬ ized by the inlet (3) opening into the splitting drum (5) in such a manner, that the material fed thereinto hits the splitting drum (5) at a position, in which the drum is moving upwards in its rotation.

2. The chipper (1) for oversized chips according to claim 1, characterized by the counter knife (8) being located within a region of ± 20° with respect to the highest point of the splitting drum (5) .

3. Chipper (1) for oversized chips according to claim 1 or 2, characterized by the chipper knives (7) being arranged in successive axial rows and to the side of each other in each row, a space being provided between each pair of chipper knives ( 7 ) in a respective row, and by the counter knife being cam-shaped in order to permit the chipper knives to pass ( 7 ) through the recesses and the teeth in the spaces between the pairs of chipper knives ( 7 ) .

AMENDED CLAIMS

[received by the International Bureau on 14 April 1997 (14.04.97) original claims 1-3 replaced by amended claims 1-3 (1 page)]

1. A chipper (1), comprising a housing (2) having an inlet (3) for the material to be chipped, an outlet (4) for the chipped material, a rotatable splitting drum (5) within the housing (2), rotating about a substantially horizontal axis (6) and provided at its circumferential surface with chipper knives (7) , and a counter knife (8) fixed inside the housing (2), the inlet (3) opening towards the splitting drum (5) in such a manner that the material fed thereinto hits the splitting drum (5) below its highest point at a position, in which said drum is moving upwards in its rotation towards said position, characterized in that the chipper knives (7) are arranged in successive axial rows and to the side of each other in each row, a space being provided between each pair of chipper knives (7) in a respective row, and in that the counter knife (8) is cam-shaped to allow the passage of the chipper knives through the recesses and the teeth in the spaces between the pairs of chipper knives (7) .

2. The chipper (1) according to claim 1, characterized by the counter knife (8) being located within a region of ± 20° with respect to the highest point of the splitting drum (5) .

3. Chipper (1) according to claim 1 or 2, characterized by an axially extending, open groove (10) being provided between each knife holder (9) and the subsequent knife (7) .