EP1608493B1 - Procede permettant de produire une plaque d'usure pour une dechiqueteuse a disque et plaque d'usure de dechiqueteuse a disque - Google Patents

Procede permettant de produire une plaque d'usure pour une dechiqueteuse a disque et plaque d'usure de dechiqueteuse a disque Download PDF

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Publication number
EP1608493B1
EP1608493B1 EP04712064A EP04712064A EP1608493B1 EP 1608493 B1 EP1608493 B1 EP 1608493B1 EP 04712064 A EP04712064 A EP 04712064A EP 04712064 A EP04712064 A EP 04712064A EP 1608493 B1 EP1608493 B1 EP 1608493B1
Authority
EP
European Patent Office
Prior art keywords
wear plate
knife
wear
disc
hardening
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
EP04712064A
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German (de)
English (en)
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EP1608493A1 (fr
Inventor
Arvo Jonkka
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Valmet Technologies Oy
Original Assignee
Metso Paper Oy
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Filing date
Publication date
Application filed by Metso Paper Oy filed Critical Metso Paper Oy
Publication of EP1608493A1 publication Critical patent/EP1608493A1/fr
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Publication of EP1608493B1 publication Critical patent/EP1608493B1/fr
Anticipated expiration legal-status Critical
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27L—REMOVING BARK OR VESTIGES OF BRANCHES; SPLITTING WOOD; MANUFACTURE OF VENEER, WOODEN STICKS, WOOD SHAVINGS, WOOD FIBRES OR WOOD POWDER
    • B27L11/00—Manufacture of wood shavings, chips, powder, or the like; Tools therefor
    • B27L11/005—Tools therefor

Definitions

  • the present invention concerns a method in accordance with the preamble of Claim 1 for manufacturing a wear plate of a disc chipper, and it also concerns a wear plate of a disc chipper.
  • Disc chippers are generally used for producing wood chips to be used for pulp production.
  • the knife disc of a disc chipper is equipped with knives attached thereto in radial direction, said knives cutting chips from a log against a fixed counter knife.
  • Other portions of the wear plates are made of high-tensile material with relatively low strength that can be worked easily.
  • the knives are attached against the tapered wear plates by means of knife clamps.
  • Percussion forces are exerted on the knives and via knives to the tapered tips of the wear plates by the logs during the chipping, whereby the forces tend to bend the tip portion of the wear plate.
  • the surfaces of the traditional wear plates facing the knife and being used about until 1990 are of general construction steel by their hardness (hardness about HB 150), they do not always form an adequately strong support against the knife, and they gradually yield and bend. As a result of the yielding, a small gap arises between the knife and the wear plate, where fibres start to accumulate. The support of the knife is weakened by the transformation of the supporting surface.
  • a known solution of the above problem is the "cassette system" developed after 1980, comprising elements to be supported against a hardened wear plate for fixing the knives.
  • the most general cassette system known in the art is described i.e. in publication DE-A1-33 14 127 (Iggesund Tools).
  • the cassette system comprises a plurality of machined elements, which naturally causes additional investment costs of the chipper.
  • the cassette system also has typically more stages in changing of the knifes.
  • the blanks of the wear plates are pre-worked, after which the front surface is plated with wear-resisting material.
  • the plating is powder that is sprayed and melted (sintered) on the surface of the plate by means of heat treatment. Temperature of the melting furnace is over 1000°C.
  • the wear plate blank In connection with the heat treatment, the wear plate blank usually encounters deformations to some extent that cannot be foreseen, whereby the most important dimensions of the wear plate in respect of the operation of the wear plate are machined only after the heat treatment. This is known from WO-A-02/060 663 .
  • the wear plate In order to prevent permanent deformation of the surface of the wear plate facing the knife, the wear plate should be hardened.
  • a problem with the heat treatment in connection with the hardening of the massive wear plate with a diameter of about 100 mm is changing of the dimensions of the wear plate, and that the fabricating of the wear plate is more difficult after the hardening.
  • a throughout hardened wear plate is too brittle, and in cases where the chipper is damaged, it can fall to pieces and destroy the whole chipper.
  • the tip of the wear plate stressed by the knife is selectively hardened by heat treatment in connection with sintering, so that its strength and yield limit duplicate or triplicate Due to the selective hardening, the toughness of the wear plate remains mainly good.
  • One prominent advantage of the invention is that the focused selective hardening is inexpensive, because it is performed in connection with the heat treatment of the sintering.
  • Figure 1 shows a front view of a knife disc 2 of a disc chipper said disc rotating around a horizontal axis 1.
  • Knives 3 attached to the disc extend from the centre of the disc towards the outer edge of the disc. The point lines of the knives 3 are direct and on a same plane with each other, perpendicular to the axis 1 of the disc. Knives 3 are attached to the inclined wear plate sectors 4 between them ( figure 2 ). During the chipping, the wear plates 4 of the rotating disc 2 rub against the log 6 being supported by the fixed counter knife 5. Thus, the front surface 7 of the wear plate is exposed to strong abrasion, whereby it is plated with a wear-resisting material 8.
  • the wear plate 4 is attached to the knife disc with bolts 9, as shown in figure 3 .
  • the knife is pressed against the surface 10 of the wear plate facing the wear plate by means of a knife clamp 11 and a bolt 12. In case the knife is pressed too strongly against the surface 10 of the wear plate, the surface 10 can yield.
  • force F is exerted on the knife 3, as shown in figure 3 , that can be divided into components F N and F p .
  • F p is exerted on the end support 13 of the knife, said support being formed of a bracket of the wear plate 4.
  • Knife 3 is abutting with the end support 13 via adjustment bolts 14 of its width, whereby force F p is exerted on a relatively small area.
  • the force component F N is exerted on the surface 10 of the wear plate and especially on the tip portion 15 thereof. Also therefore the surface 10 for the part of the tip portion 15 yields in a wear plate of prior art.
  • the knife can move or vibrate, which speeds up the deformation of the wear plate.
  • the support portion 13 of the wear plate wears and the positions of the surfaces 10 of the wear plates change, also the positions of the different knifes differ from each other.
  • the knife allowance V differs from one knife to another.
  • Big knife allowance brings about fine grains and long strings from the sapwood, detrimental to the further processing. Solution shown in figures 1-3 is not suitable to narrow knives.
  • the knife cassette comprises hardened elements 28, 29 and a bolt 30 locking them together.
  • the bolt 30 is loosened so much that the knife 31 fits in between the elements.
  • the bolt 30 is tightened, whereby the elements 28, 29 press the turn-able knife 31 in position.
  • the cassette with the knife 31 is positioned between the knife clamp 27 and the knife disc 2'.
  • the knife clamp 27 between the wear plate 4' and the knife is pressed against the cassette by means of a bolt 32. Chipping forces from the knife 31 are exerted on the hardened elements 28, 29 having less yielding. Thus, also the force exerted on the knife clamp 27 is more even.
  • the knife clamp is usually medium-hard tempered steel with a hardness of 300 HB. Cassette systems, however, include numerous hardened elements that are destroyed in cases where metallic scrap or stones end up into the chipper. That causes big maintenance costs.
  • Temperature of the tip 15 of the wear plate during the hardening process is shown in figures 5 and 6 .
  • Horizontal axes of the figures describe time and vertical axes temperature. Changes of the temperature in the wear plate have been measured m hardening tests.
  • Straight C of figure 5 describes the change of the surface temperature of the tip 15 after the sintering and immediately after the wear plate is removed from the furnace. The figure shows, that the temperature of the tip 15 decreases in the early stage quickly in the ambient temperature of 20°C of air. Wet quenching has been started after about 1 minute after removal from the furnace, whereby the tip portion temperature is still within the austenitic area. The lower limit of the austenitic temperature is, depending on the percent of carbon, 840-870°C.
  • Curve D of figure 6 shows the temperature of the tip portion 15 during quenching. After quenching of about 17 minutes, when the tip portion temperature is below 100°C, the quenching was stopped. After that, the inner heat of the basic material of the wear plate increases the tip portion temperature again to more than 200°C, causing additional annealing of the tip portion 15 of the wear plate.
  • Curve E shows the maximum measured temperature of the medium portion of the wear plate.
  • the quenching can also be performed with oil, quenching liquid or compressed air.
  • Environmental aspects and handling problems must in that case be taken into consideration, and the fact that desired quick cooling and hardness is difficult to achieve.
  • Figure 7 shows water hardening of the wear plate 4, where the tip portion 15 (marked with grate lines) and the support portion 13 are cooled by means of a water jet 16 and 17 directed to the surfaces to be in contact with the knife 3 after the heat treatment of the sintering.
  • the present boric steels enable easily the selective hardening, because the boric emphasizes the hardening by 1000-1500 -fold. It is known in the metal technique that the yield limit, in other words the stiffness increases in proportion to the hardness. Tests have shown that by means of selective hardening an about double hardness can be provided to the tip 15 of the wear plate, and thus also increased permanent deformation limit in respect of other portions of the wear plate.
  • the normal hardness of the wear plate is about HB 150
  • a hardness of even more than 400 HB can be achieved in the hardened tip portion.
  • the ability of the tip of the wear plate and the support portion to encounter forces of the chipping without yielding grows considerably.
  • a bevel 19 of an angle ⁇ can be machined, whereby the wood does not rub the surface 7 for the portion, where no durable coat layer 8 exists. Additionally, it will be made sure that the point 22 of the tip portion 15 sets to the cover of the knife 3. The wear resistance of the point 22 will be improved, when the yielding softer material has been removed. Hardness of the wear plate quite for the part of the sharpest point 22 is important so as to avoid gathering of cuttings and fibres between the knife 3 and the machined surface 20 of the wear plate.
  • Supporting element for the knife 3 can also be formed of a part 23 separate from the wear plate, as shown in figure 2 .
  • the part 23 is manufactured separately from the wear plate.

Landscapes

  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Wood Science & Technology (AREA)
  • Forests & Forestry (AREA)
  • Crushing And Pulverization Processes (AREA)
  • Powder Metallurgy (AREA)
  • Heat Treatment Of Articles (AREA)

Claims (7)

  1. Procédé pour la production des plaques d'usure pour une déchiqueteuse à disque, où la surface avant (7) d'une billette (4) de la plaque d'usure est plaquée par frittage dans un four à une température de 900 - 1100 °C avec un matériau resistant à l'usure (8), caracterisé en ce que lorsque la température de la billette de la plaque d'usure se trouve après le frittage encore dans la zone austénitique (plus de 840 - 870 °C), un trempage selectif et un durcissement par un refroidissement sélectif forcé sont dirigés à la partie au bout (15) de la plaque d'usure.
  2. Procédé pour la production des plaques d'usure pour une déchiqueteuse à disque selon la revendication 1, caracterisé en ce que le trempage selectif et le durcissement par un refroidissement selectif forcé sont aussi dirigés à la partie de support (13) de la plaque d'usure.
  3. Procédé selon l'une quelconque des revendications 1 à 2, caraterisé en ce que le durcissement des zones à durcir est réalisé au moyen d'un jet selectif d'un agent de refroidissement.
  4. Plaque d'usure d'une déchiqueteuse à disque, où la surface avant (7) d'une billette (4) de la plaque d'usure est plaquée par frittage en surface avec un matériau resistant à l'usure (8) dans un four, à une température de 900 - 1000 °C, caractérisée en ce que, lorsque la température de la billette de la plaque d'usure se trouve après le frittage encore dans la zone austénitique (plus de 840 - 870 °C), un trempage selectif et un durcissement par un refroidissement sélectif forcé sont realisés au moins à une surface (20 ; 21) destinée à supporter un couteau déchiqueteur (3), cette surface, respectivement ces surfaces, possédant une plus grande dureté et limite élastique que les autres parties de la plaque d'usure.
  5. Plaque d'usure (4) d'une déchiqueteuse à disque selon la revendication 4, caractérisée en ce que la partie au bout (15) de la surface (20) destinée à supporter un couteau déchiqueteur (3) est sensiblement plus dur que la dureté moyenne de la surface (20).
  6. Plaque d'usure (4) d'une déchiqueteuse à disque selon les revendivations 4 et 5, caractérisée en ce qu'une partie de la surface avant du bout (15) décarburisée pendant le trempage et le durcissement a été enlevé en usinant jusqu'au matériau à surface dure (19).
  7. Plaque d'usure d'une déchiqueteuse à disque selon quelconque des revendivations 4 à 6, caractérisée en ce que la billette de la plaque d'usure est fabriquée de l'acier borique comprenant environ C = 0,20 - 0,25 %, Si = 0,2 %, Mn = 1,2 %, Ni = 0,04 %, Cr = 0,27 %, Al = 0,03 %, B = 0,002 % et Fe environ 98 %.
EP04712064A 2003-03-28 2004-02-18 Procede permettant de produire une plaque d'usure pour une dechiqueteuse a disque et plaque d'usure de dechiqueteuse a disque Expired - Fee Related EP1608493B1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FI20030464A FI115389B (fi) 2003-03-28 2003-03-28 Menetelmä kiekkohakkurin kulutuslevyn valmistamiseksi ja kiekkohakkurin kulutuslevy
FI20030464 2003-03-28
PCT/FI2004/000074 WO2004085124A1 (fr) 2003-03-28 2004-02-18 Procede permettant de produire une plaque d'usure pour une dechiqueteuse a disque et plaque d'usure de dechiqueteuse a disque

Publications (2)

Publication Number Publication Date
EP1608493A1 EP1608493A1 (fr) 2005-12-28
EP1608493B1 true EP1608493B1 (fr) 2010-04-07

Family

ID=8565884

Family Applications (1)

Application Number Title Priority Date Filing Date
EP04712064A Expired - Fee Related EP1608493B1 (fr) 2003-03-28 2004-02-18 Procede permettant de produire une plaque d'usure pour une dechiqueteuse a disque et plaque d'usure de dechiqueteuse a disque

Country Status (5)

Country Link
EP (1) EP1608493B1 (fr)
BR (1) BRPI0405653A (fr)
DE (1) DE602004026425D1 (fr)
FI (1) FI115389B (fr)
WO (1) WO2004085124A1 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130026810A1 (en) * 2011-07-25 2013-01-31 Kennametal Inc. Cutting Tool Assembly with Protective Member
US9168672B2 (en) * 2012-07-24 2015-10-27 Key Knife, Inc. Knife with disposable inserts

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1443900A (en) * 1973-03-30 1976-07-28 Crucible Inc Powder metallurgy tool steel article
US4002471A (en) * 1973-09-24 1977-01-11 Federal-Mogul Corporation Method of making a through-hardened scale-free forged powdered metal article without heat treatment after forging
DE19521941C1 (de) * 1995-06-07 1996-10-02 Mannesmann Ag Verfahren und Vorrichtung zur Herstellung von Sinterteilen
FI99281C (fi) * 1996-07-10 1998-05-25 Sunds Defibrator Woodhandling Kiekkohakkurin teräkiekkojärjestely ja kulutuslevyn saranalista
AU4032899A (en) * 1998-05-16 1999-12-06 B. Maier Zerkleinerungstechnik Gmbh Blade ring cutter
US6019937A (en) * 1998-11-27 2000-02-01 Stackpole Limited Press and sinter process for high density components
FI114784B (fi) * 2001-02-02 2004-12-31 Metso Paper Inc Menetelmä kiekkohakkurin kulutuslevyn korjaamiseksi ja kiekkohakkurin kulutuslevy
FI20011460A0 (fi) * 2001-07-04 2001-07-04 Metso Paper Oy Menetelmä kiekkohakkurin terän alustan kulutuskestävyyden lisäämiseksi ja terän alustan omaava kiekkohakkuri

Also Published As

Publication number Publication date
BRPI0405653A (pt) 2005-07-05
WO2004085124A1 (fr) 2004-10-07
FI20030464A (fi) 2004-09-29
FI20030464A0 (fi) 2003-03-28
EP1608493A1 (fr) 2005-12-28
DE602004026425D1 (de) 2010-05-20
FI115389B (fi) 2005-04-29

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