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Dokumentenidentifikation EP0512299 22.08.1996
EP-Veröffentlichungsnummer 0512299
Titel Gegenmesser für einen Disk-Zerspaner
Anmelder Andritz-Patentverwaltungs-Ges.m.b.H., Graz, AT
Erfinder Svensson, Ake, S-890 23 Själevad, SE;
Olofsson, Anders, S-891 32 Örnsködsvik, SE;
Hannimäki, Ari, SF-15860 Salpakangas, FI;
Kokko, Pekka, SF-16710 Hollola kk, FI
Vertreter derzeit kein Vertreter bestellt
DE-Aktenzeichen 69212213
Vertragsstaaten DE, FR, SE
Sprache des Dokument En
EP-Anmeldetag 16.04.1992
EP-Aktenzeichen 921066817
EP-Offenlegungsdatum 11.11.1992
EP date of grant 17.07.1996
Veröffentlichungstag im Patentblatt 22.08.1996
IPC-Hauptklasse B27L 11/02

Beschreibung[en]

The present invention relates to a counter blade for a disc chipper designed for the chipping of wood, as defined in the introductory part of claim 1.

The production of wood chips for the paper and pulp industry is generally implemented using disc chippers, in which the wood is chipped by means of blades mounted in a radial or nearly radial arrangement on a disc . As the disc rotates, the blades strike against the log under chipping, the opposite side of which leans against the counter blade. The counter blade is located at the delivery end of the feed funnel, on the opposite side relative to the direction of motion of the blade. The wood may be fed into the disc chipper either vertically or horizontally, and the chipper is accordingly called a horizontal-feed or a vertical-feed chipper. There are corresponding differences in the positions of the disc and blades in these different chipper types, but in principle they are identical in operation.

In a disc chipper, the parts subject to wear are the chipping blade and the counter blade, which receives the log being chipped. For the chips produced to be suitable for use as fibrous material, the counter blade must meet certain requirements regarding its condition. The cutting edge of the counter blade, i.e. the arris receiving the log, must not have an excessive radius of curvature, otherwise the wood fibres will be broken and the result is low-quality chips containing sawdust.

In prior art, the counter blade consists of a relatively large and bulky body that requires plenty of material and is difficult to handle during installation and maintenance. The wearing part of the counter blade is provided with a hard-metal coating which needs renewal at times. At present, there are also counter blades of a lighter construction which are free of the above-mentioned drawbacks. However, there is still the problem that different parts of the cutting surface of the counter blade are unevenly worn due to the uneven distribution of the logs. For this reason, the counter blade cannot be utilized in full.

To achieve an optimal chipping efficiency, the counter blade in a vertical-feed chipper consists of a horizontal part and another part placed in a direction slightly differing from the horizontal, so that the blade parts are at an angle slightly diverging from 180° relative to each other. In a blade construction like this, the horizontal blade area close to the junction of the parts is subject to the hardest wear, due to the manner in which the logs are directed in the feed funnel, and so the wear in this area determines the need for blade replacement. Therefore, when this small area of the whole effective surface of the blade has worn out, the whole blade must be replaced. If the counter blade has a hard-metal coating, renewing the coating means re-coating the whole blade.

The object of the invention is to eliminate the drawbacks referred to above and to produce a new, more advantageous counter blade construction. According to the invention, this is achieved in the manner defined in the characterization part of claim 1. Other preferred embodiments are presented in the subclaims.

The invention allows the counter blade to be effectively utilized as only the worn part of the blade needs to be replaced. In respect of manufacturing techniques, the counter blade of the invention is advantageous since it does not involve any difficult angular structures. By using blade parts of a symmetrical cross-section, it is possible to provide each blade part with two cutting surfaces. Also, it is possible to swap the two counter blade pieces to replace the more worn part with the less worn one.

In the following, the invention is described by the aid of one its embodiments by referring to the drawings attached, in which

  • Fig. 1 presents a cross-section through a vertical-feed chipper, showing the position of the counter blade,
  • Fig. 2 presents the counter blade construction of the invention, and
  • Fig. 3 presents a cross-section through the counter blade in Fig. 2 as sectioned along line A-A.

As illustrated by Fig. 1, a vertical-feed chipper consists of a chipper frame 1 accommodating a counter blade carrier 2 movable relative to the frame. At the upper part of the counter blade carrier 2 there is a feed space which, together with a hollow space communicating with the log conveyor (not shown), forms a gravity funnel 3. Attached e.g. by means of bolts (not shown) to the counter blade carrier 2 is a counter blade holder 4, placed at the delivery end of the gravity funnel 3. The counter blade piece 5 is attached by means of bolts to a groove 7 provided in the counter blade holder 4. The surfaces of the counter blade holder 4 and counter blade piece 5 facing the gravity funnel 3 form a continuous and essentially even surface allowing the logs to slide over it. The cutting edge of the counter blade consists of an arris 8 located at the delivery end of the gravity funnel 3.

At the delivery end of the gravity funnel 3, next to the counter blade carrier 2 provided with the counter blade holder 4 and counter blade 5 there is a space housing a vertically mounted chipper disc 9 rotating on its shaft. The shaft and the power means rotating the disc, which are suitably mounted on the chipper frame, are not shown and they can be implemented in a manner known in the art. The chipper disc 9 accommodates several, usually 12 -16 blade bodies 10 provided with cutting blades 11 and mounted on the disc in a manner known in itself.

The logs are brought to the funnel by means of conveyors and directed into the chipper in a manner known in itself. The blades of the disc 9 cut the wood into chips of a desired size. The chip length can be determined by adjusting the distance T between the blades 11 and stoppers provided in the disc. This is done by moving the blade body 10 so as to obtain a suitable distance T, preferably approx. 13 mm. To achieve a good chipping efficiency, the distance C between the blade 11 and the counter blade must be correct, suitably approx. 0.5 mm. The arris 8 forming the cutting edge of the counter blade must not be allowed to be rounded too much by wear. The radius of curvature must remain below 5 mm to ensure that the wood fibres are not damaged and that the chips produced-will not contain sawdust.

Fig. 2 depicts the counter blade holder 4 and one of the two counter blade pieces 5 accommodated by it as seen from the side facing the disc 9. The holder 4 is provided with a groove 7 for the counter blade pieces 5. The groove extends over the whole length of the holder and is bent into an angle δ at a point midway between the ends. The thickness of that part of the holder which lies above the groove decreases towards the edge so that its surface 16 constitutes part of the wall of the funnel 3. The counter blade holder 4 is fixed to the counter blade carrier 2 by means of bolts screwed into holes 12.

The counter blade consists of two identical counter blade pieces 5. Each part has two longitudinal arrises 8 and 8' placed at a distance from each other and forming the cutting edge of the counter blade. The counter blade piece has a cross-section symmetrical in relation to plane B-B, which, as shown in Fig. 3, is equally distanced from the arrises 8 and 8' and perpendicular to the normal connecting the two arrises. When the two counter blade pieces are placed in the groove 7 in the holder 4, the cutting surface of the counter blade has an elbow equal to angle δ. The end faces 14 of the counter blade pieces 5 form an angle α diverging from the straight angle relative to the longitudinal side of the part 5. Angle α is determined by the angle of the elbow at point 13. Thus, the parts can be so fitted together that a continuous blade surface 8 is formed at the upper edge of the counter blade.

In a preferred embodiment of the invention, as illustrated by Fig. 3, each counter blade piece 5 is provided with four parallel arrises 8, 8' 18, 18', each of which is so made that it can act as the cutting edge of the counter blade. When the piece is in position, two of the arrises always face towards the chipper disc 9. One of these two arrises acts as the cutting edge. The other two arrises are essentially on the opposite side of the counter blade piece 5 as seen in the direction of the shaft of the disc 9. The counter blade piece is symmetrical in relation to plane B-B. Plane B-B is perpendicular to the normal connecting the adjacent arrises 8 and 8' forming a cutting edge and correspondingly arrises 18 and 18'. It is located at an equal distance from each arris 8,8' and similarly from arrises 18 and 18'. Thus, each counter blade piece 5 has altogether four arrises, each of which can be used as a counter blade surface by turning the piece.

In a preferred embodiment, the lower part of the end face 14 of the counter blade pieces forms an angle of 180-2α relative to the upper part of the end face. This renders the horizontal and oblique blade parts interchangeable. This is practical because the horizontal part of the counter blade is subject to faster wear than the oblique part, which is due to the fact that the logs under chipping tend to move horizontally side by side in the feed funnel. The minimum requirement is that the cutting edges of the two blade pieces 5 should be in contact with each other. It is possible to place supporting or filling elements between the lower parts of the counter blade pieces to achieve a continuous overall structure. It is also possible to provide the counter blade pieces with end faces constituting parallel planes relative to each other. In this case, a given counter blade piece can only be used in one position as the end faces of the other part of the counter blade slant in another direction.

The counter blade pieces 5 are attached to the counter blade holder 4 by means of bolts or equivalent placed in holes 15. The bolts may extend through the counter blade carrier 2 as shown in Fig. 1. The holes are symetrically laid out so as to allow the pieces 5 to be mounted in alternative positions and locations using the same holes and fixing elements. The pieces can be joined by their ends to each other or to the above-mentioned supporting structures e.g. by means of mortise-and-tenon joints.

Fig. 3 presents a cross-section of the counter blade holder 4 and counter blade piece 5 as taken along line A-A in Fig. 2. Part 16 of the holder 4 is at an angle β relative to the vertical plane. The counter blade piece 5 is in the groove 7 and has a part 17 shaped in the same angle with the holder and protruding out of it. The front surface 28 of the counter blade piece is in a vertical position, so that arris 8 constitutes the cutting edge of the counter blade.

In the above, the invention has been described with reference to one of its embodiments. However, the invention is not restricted to this embodiment, but the scope of patent protection may vary within the limits permitted by the following claims.


Anspruch[en]
  1. Counter blade designed for use in a chipping machine which comprises a chipper disc (9) rotatably mounted in the chipper frame (1) by means of a shaft supporting the disc, and in which the counter blade is mounted in the chipper frame (1) essentially at the intersection of a blade (11) mounted in the chipper disc (9) and the log to be chipped, in such manner that, on the side opposite to the chipping blade (11), the counter blade rests against the log to be chipped, said counter blade (5) consisting of a first and a second blade part placed at an obtuse angle relative to each other, characterized in that the counter blade consists of two essentially elongated pieces (5) having an arris (8,8') forming the cutting edge of the counter blade at least on one of its longitudinal sides, the end faces (14) of said counter blade pieces (5) being so formed as to permit connection to the adjacent counter blade piece (5) so that the two counter blade pieces form a continuous cutting edge of the counter blade.
  2. Counter blade according to claim 1, characterized in that the counter blade pieces (5) have two parallel arrises (8,8') which are so formed that they can act as counter blade surfaces and which are placed at a distance from each other.
  3. Counter blade according to claim 1, characterized in that the counter blade pieces (5) have four parallel arrises (8,8',18,18') which are designed to act as counter blade surfaces and which, when the counter blade piece (5) is mounted in place, are so located that two (8,8') of the arrises, placed at a distance from each other, are on that side of the counter blade piece which faces towards the chipper disc (9), while the other two arrises (18,18') are essentially on the opposite side of the counter blade piece (5) as seen in the direction of the shaft of the chipper disc (9).
  4. Counter blade according to claim 2 or 3, characterized in that the counter blade pieces (5) are of a cross-section symmetrical relative to plane B-B, which is perpendicular to the normal between adjacent arrises (8,8') constituting a cutting edge and equally distanced from said arrises.
  5. Counter blade according to any one of the preceding claims, characterized in that the end faces (14) are so shaped that each counter blade piece (5) can be mounted in the place of either one of the two parts of the counter blade (5).
  6. Counter blade according to claim 5, characterized in that the end faces (14) of the counter blade pieces (5) are so shaped that a gap is formed between them and that the counter blade holder (4) is provided with a supporting or filling part that substantially fills the gap.
  7. Counter blade according to any one of the preceding claims, characterized in that, on the side essentially opposite to the arris (8,8') constituting the cutting edge, the counter blade pieces (5) are attached to the counter blade holder (4) by means of fixing elements fitted into the counter blade pieces (5) and the counter blade holder (4), while the counter blade holder (4) is attached to the counter blade carrier (2), which again is attached to the chipper frame (1).






IPC
A Täglicher Lebensbedarf
B Arbeitsverfahren; Transportieren
C Chemie; Hüttenwesen
D Textilien; Papier
E Bauwesen; Erdbohren; Bergbau
F Maschinenbau; Beleuchtung; Heizung; Waffen; Sprengen
G Physik
H Elektrotechnik

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