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WO1993002836A1 - Procede et appareil permettant d'affuter la surface d'une meule de defibreur - Google Patents

Procede et appareil permettant d'affuter la surface d'une meule de defibreur Download PDF

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Publication number
WO1993002836A1
WO1993002836A1 PCT/FI1992/000224 FI9200224W WO9302836A1 WO 1993002836 A1 WO1993002836 A1 WO 1993002836A1 FI 9200224 W FI9200224 W FI 9200224W WO 9302836 A1 WO9302836 A1 WO 9302836A1
Authority
WO
WIPO (PCT)
Prior art keywords
grindstone
sharpening
water jet
nozzle
pulp
Prior art date
Application number
PCT/FI1992/000224
Other languages
English (en)
Inventor
Jukka LÄHTEENMÄKI
Seppo Blomqvist
Juhani Valli
Original Assignee
Valmet-Tampella Oy
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Valmet-Tampella Oy filed Critical Valmet-Tampella Oy
Priority to JP5503081A priority Critical patent/JPH07500775A/ja
Priority to DE4292499T priority patent/DE4292499T1/de
Priority to GB9402153A priority patent/GB2274079B/en
Publication of WO1993002836A1 publication Critical patent/WO1993002836A1/fr
Priority to SE9400424A priority patent/SE503135C2/sv

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B53/00—Devices or means for dressing or conditioning abrasive surfaces
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21B—FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT
    • D21B1/00—Fibrous raw materials or their mechanical treatment
    • D21B1/04—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres
    • D21B1/12—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres by wet methods, by the use of steam
    • D21B1/14—Disintegrating in mills
    • D21B1/28—Dressers for mill stones, combined with the mill

Definitions

  • the object of the invention is a method of sharpening the surface of a grindstone in a pulp grind ⁇ er, wherein material is removed from the surface of the grindstone, from part of the surface of the grindstone at a time, and essentially from the whole surface area.
  • Another object of the invention is an apparatus for carrying out the method, comprising sharpening means for removing material from the surface of the grind ⁇ stone, from part of the surface area at a time.
  • the grindstone is conditioned by sharpening, which in this case means that material is removed from the sur ⁇ face of the grindstone to give it the desired quality. Conventionally, this is carried out by passing a burr along the surface of the grindstone, the burr being pressed against the surface of the grindstone while said grindstone is being rotated. Consequently, material becomes detached from part of the surface of the grindstone, i.e.
  • a blunted grindstone can be resharpened with a burr of a suitable shape.
  • a solution of this kind is known e.g. from Finnish Patent 26,584.
  • the purpose of this invention is to provide a method and an apparatus for sharpening a grindstone, by which method and apparatus sharpening can be carried out easily and simply and breaking of abrasive grains can be prevented, whereby variation in the properties of pulp caused by sharpening can be essentially limited from what it is now. It is characteristic of the method of the invention that at least one water jet is directed to the surface of the grindstone, the feed pressure of the water jet being so high that the water jet detaches from the surface of the grindstone bonding material found between abrasive grains, and that the whole sur ⁇ face of the grindstone is treated at the entire width thereof by a water jet of this kind while the grindstone is being rotated.
  • the sharpening means comprise at least one nozzle and a high pressure pump arranged to pump a high pressure water jet through the nozzle against the surface of the grindstone while the grindstone is rotated during the sharpening thereof.
  • the essential idea of the invention is that the surface of the grindstone is sharpened by subjecting it to water jets affecting a small surface area and having such high pressure that bonding material found between abrasive grains becomes detached from the surface of the grindstone, whereby the abrasive grains come better into sight and, when sufficient bonding material has been removed, the utmost and worn abrasive grains become detached.
  • the water jet or jets are moved during the sharpening while the grindstone rotates slowly in the direction of the axle thereof, whereby the whole grind ⁇ stone can be sharpened in the same manner and the sharpening can be carried out by a suitable embodiment of the apparatus even during the grinding,' which sim- plifies the sharpening and eliminates the break in pro ⁇ duction normally needed for sharpening.
  • Figure 1 shows a schematic side view of sharpening by a water jet
  • Figure 2 shows a top view of the sharpening depicted in Figure 1
  • Figure 3 shows a schematic view of controlling of water jet sharpening.
  • Figure 4 shows schematically the effect of water jet sharpening and, on the other hand, of burring on the freeness value of pulp
  • Figure 5 shows schematically the effect of water jet sharpening on the production rate of a grind ⁇ er
  • Figure 6 shows the freeness value of pulp as a function of time in both burring and water jet sharpen ⁇ ing, measured in connection with a practical test
  • Figure 7 shows the sharpness index of a grind ⁇ stone as a function of time in both burring and water jet sharpening, measured in connection with a practical test.
  • Figure 1 shows a grindstone 1 rotating about an axle la.
  • Today on the surface of the grindstone 1 is typically an actual grinding surface lb consisting of grinding blocks made of ceramics or a ceramic mixture or the like, the grinding surface grinding fibre off the wood.
  • a high pressure water jet 2 is directed onto the surface of the surface layer lb of the grindstone from a nozzle 3.
  • the nozzle 3 is moved by a separate transfer apparatus or transfer means 4 in the direction of the axle of the grindstone 1 in order that the water jet might be directed onto the whole surface of the grind ⁇ stone 1 in a desired manner and at a desired angle.
  • a water pipe -5 leads to a high pressure pump 6, which raises the pressure of the water coming from the water feed point, such as a con ⁇ tainer 7 or the like, sufficiently high.
  • a water jet was used in which the distance between the nozzle and the surface of the grindstone was about 2 cm and the width of the water jet at the point where it hits the surface was from 2 to 2.5 cm, the thickness of the water jet being about 0.5 cm.
  • the values of water feed pressure used in the tests varied between 200 and 2,500 bar, the typical quantity of water supplied being about 51/min.
  • the water jet had a kind of chisel-shaped cross section, this is not in any way necessary but water jets of any other shape can also be used.
  • Figure 2 shows a top view of the apparatus according to the figure, showing how the surface layer lb of the grindstone 1 consists of separate blocks.
  • the transfer apparatus 4 is arranged such that the nozzle 3 and thereby the water jet 2 extend over the entire width of the grindstone 1.
  • the nozzle 3 is positioned within a certain distance, whereby the shape of the water jet and the kinetic energy generated by the feed pressure are sufficient and suitable to detach bonding and filling material found between abras- ive grains such that the abrasive grains come better into sight and worn abrasive grains are capable of be ⁇ coming detached from the surface lb of the grindstone.
  • the transfer means or transfer apparatus 4 presented in Figures 1 and 2 can be any kind of apparatus known per se, having a cross beam 4a in the axial direction of the grindstone extending over the width thereof, and a carrier or other such member 4b moving therealong, the actual nozzle or nozzles 3 being attached thereto to move along the transfer beam 4a therewith.
  • the carrier 4b can be moved along the transfer beam 4a either by means of a feed screw, a chain mechanism, a cylinder, some other motor or transmission solution, or in any other manner generally known per se.
  • the nozzle or nozzles 3 can be attached to the carrier 4b to move transverse to the axle of the grindstone 1, whereby the distance of the nozzle 3 from the surface of the grind ⁇ stone 1 can be adjusted in a desired manner.
  • the nozzles 3 can be attached movably with respect to the carrier 4b in any manner known per se, by means of glide, screw, etc. structures, and the nozzles can be arranged to be moved either manually or automatically by means of a power unit. Since structures like this are generally known per se, and so are the structures and operation of the apparatuses suitable for use as transfer apparatuses, it has not been considered necessary to describe either of these any closer herein.
  • Figure 3 shows schematically automatic or almost automatic sharpening of a grindstone by a grinder such that the sharpening can be carried out at suitable intervals.
  • a grinder 8 wood 9 is pressed against the grindstone 1 by means of plungers 10 in a manner known per se while water is sprayed conventionally onto the grinding zone, whereby pulp 11 is formed.
  • the grinder can naturally also be provided with any other known wood feed mechanism, such as different chain feed structures or screw feed solu ⁇ tions.
  • the pressure pump 6 is started and sharpening by means of a water jet 2 by moving the nozzle 3 is carried out until the values measured indicate that the grinder is in the desired area of operation and the sharpening can be stopped. Further, sharpening can be carried out by treating the surface of the grindstone for a predetermined time, whereafter grinding is continued and the freeness value and the other values to be measured are monitored, whereafter this kind of periodic sharpening can be repeated at suitable intervals, e.g. in about every two hours, until the desired values of operation are reached as a result of sharpening.
  • Figure 4 shows schematically the variation in the freeness value of the pulp produced by a grinder, in both burring and water jet sharpening.
  • Figure 4 shows the line A, which forms a sawlike pattern, illustrating as a function of time the change in the freeness value of pulp brought about by burring.
  • the line B illustrates the desired value or set value where the freeness, in theory, should be, and the curve C illustrates as a function of time the variation in the freeness value in water jet sharpening.
  • the freeness value increases heavily in burring, where ⁇ after it decreases fairly steadily as the grinding pro ⁇ gresses until the grindstone again needs sharpening.
  • the interval between sharpenings is several days, typically about two weeks, during which time the freeness value may vary e.g. ⁇ 30 - 40% of the mean value. This affects significantly the properties of the pulp produced and the range of variation is quite signi- ficant.
  • sharpening illustrated by the curve C sharpening can be carried out at shorter intervals, which means that water jet sharpening can be carried out e.g..at an interval of two or three days. Since in burring extra material must be in practice removed from the surface of the grindstone in order that one might be sure of the result of the sharpening, water jet sharpening, which removes essentially less material, makes it possible to repeat sharpening more often without decreasing the operating life of the grindstone.
  • Figure 5 shows schematically the effect of burring and water jet sharpening on output obtained by a grinder, the curve D illustrating the output obtained by burring as compared with the theoretic maximum out ⁇ put, the line E illustrating schematically the theoretic maximum output, and the curve F illustrating the output obtained by water jet sharpening.
  • the curves in Figure 5 illustrate a situation where the maximum output obtained by sharpening is set to correspond to the the- oretic maximum output E.
  • the output brought about by the sharpness reached by burring, illustrated by the curve D is very wavy, and between the line E and the curve D remains a biggish area ⁇ P, which represents the loss in production brought about by incapability of maintain ⁇ ing the production high owing to the properties of the surface of the grindstone.
  • the curve F in turn illustrates the output obtained by water jet sharpening as compared with the theoretic maximum output E. As illustrated by the curve F, variation in output is very little in water jet sharpening and only slightly wavy. Consequently, when water jet sharpening is used for a grinder, the areas ⁇ P between the curves D and F marked with lines can also be utilized, the areas representing an addition in output obtained by using water jet sharpening and thus the advantages of water jet sharpening over burring.
  • Figure 6 shows a measuring result obtained, in practice, of the variation in the freeness of pulp when sharpening is performed with a burr on the one hand and by a water jet on the other hand.
  • Figure 6 shows that when burring is used (curve G), the freeness varies between the values 225 and 110 (ml) between two sharpen ⁇ ings.
  • curve H When water jet sharpening is used (curve H), the freeness varies, according to the curve, from about 135 to 155 (ml), the variation being less than 1/5 of the variation in the freeness brought about by burring.
  • Figure 7 shows in the corresponding manner the calculatory sharpness index of the grindstone, the value being known per se to one skilled in the art, in burring on the one hand and in water jet sharpening on the other hand.
  • the sharpness of the surface of the grindstone varies between the values 0.7 and 0.45 when burring is used (curve I), being at it is greatest af er the sharpening and decreasing considerably toward the following sharpening. Consequently, immediately after the sharpening the edges of the abrasive grains of the grindstone are sharp and tend to cut the fibres instead of detaching them longer and thus more suitable for manufacture of paper.
  • the specification and the drawings describe the invention only by way of example.
  • the invention can be applied in different ways, e.g. by using one or more jet nozzles to achieve the desired sharpening rate and ef- feet. It is characteristic that essentially the whole surface of the grindstone is sharpened in the same way in order that the sharpening result might be even. Fur ⁇ ther, since it is typical that grooves are provided on the surface of the grindstone, essentially evenly on the surface area, to improve the grinding properties of the grindstone and to facilitate removal of pulp and wa ⁇ ter, a corresponding grooving can be provided, if neces ⁇ sary, on the surface of the grindstone by the sharpening apparatus of the invention.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Wood Science & Technology (AREA)
  • Grinding Of Cylindrical And Plane Surfaces (AREA)
  • Grinding-Machine Dressing And Accessory Apparatuses (AREA)
  • Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)

Abstract

Procédé et appareil permettant d'affûter la surface d'une meule (1) dans un défibreur (8). Au cours du processus, un jet d'eau (2) qui élimine de la surface de la meule (1) la matière liante située entre les grains abrasifs est dirigé contre la surface de la meule (1) à une pression d'alimentation élevée. L'appareil comprend un ajutage (3) et un pompe à haute pression (6) faisant circuler de l'eau sous haute pression à travers l'ajutage (3). Ce dernier est relié à un dispositif de transfert (4) qui le déplace axialement par rapport à la meule (1) pendant la rotation de celle-ci.
PCT/FI1992/000224 1991-08-09 1992-08-03 Procede et appareil permettant d'affuter la surface d'une meule de defibreur WO1993002836A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
JP5503081A JPH07500775A (ja) 1991-08-09 1992-08-03 パルプグラインダにおける砥石の表面を研ぐ方法及び装置
DE4292499T DE4292499T1 (de) 1991-08-09 1992-08-03 Verfahren und Anordnung zum Schärfen der Oberfläche eines Schleifsteins einer Holzschleifmaschine
GB9402153A GB2274079B (en) 1991-08-09 1992-08-03 Method and apparatus for sharpening the surface of a grindstone in a pulp grinder
SE9400424A SE503135C2 (sv) 1991-08-09 1994-02-09 Förfarande och anordning för skärpning av ytan på slipstenen i en träslipmaskin

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI913803 1991-08-09
FI913803A FI88938C (fi) 1991-08-09 1991-08-09 Foerfarande och anordning foer skaerpning av ytan foer traeslipsmaskinens slipsten

Publications (1)

Publication Number Publication Date
WO1993002836A1 true WO1993002836A1 (fr) 1993-02-18

Family

ID=8532972

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FI1992/000224 WO1993002836A1 (fr) 1991-08-09 1992-08-03 Procede et appareil permettant d'affuter la surface d'une meule de defibreur

Country Status (7)

Country Link
JP (1) JPH07500775A (fr)
AU (1) AU2368592A (fr)
DE (1) DE4292499T1 (fr)
FI (1) FI88938C (fr)
GB (1) GB2274079B (fr)
SE (1) SE503135C2 (fr)
WO (1) WO1993002836A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0753381A1 (fr) * 1995-07-11 1997-01-15 Valmet Corporation Procédé et dispositif pour l'affûtage de la surface des pierres d'un défibreur
WO2000073571A1 (fr) * 1999-05-26 2000-12-07 Tom Forsman Procede de commande d'une operation de reduction de bois en pate mecanique
CN110293482A (zh) * 2019-07-05 2019-10-01 湖南科技大学 一种圆弧形金刚石砂轮的修锐方法

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10322991A1 (de) * 2003-05-21 2004-12-16 Erwin Junker Maschinenfabrik Gmbh Verfahren und Vorrichtung zum Schleifen eines Werkstücks
WO2006128960A1 (fr) * 2005-06-03 2006-12-07 M-Real Oyj Procede et appareil de defibrage mecanique du bois

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2222338B2 (de) * 1971-05-07 1976-05-13 Christensen Diamond Products Co., Salt Lake City, Utah (V.St.A.) Vorrichtung zum schaerfen eines kreissaegeblattes waehrend der schneidarbeit

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2222338B2 (de) * 1971-05-07 1976-05-13 Christensen Diamond Products Co., Salt Lake City, Utah (V.St.A.) Vorrichtung zum schaerfen eines kreissaegeblattes waehrend der schneidarbeit

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN, Vol. 7, No. 12, M186; & JP,A,57 168 862, 18-10-1982, (HARUNOBU MIURA). *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0753381A1 (fr) * 1995-07-11 1997-01-15 Valmet Corporation Procédé et dispositif pour l'affûtage de la surface des pierres d'un défibreur
US5727992A (en) * 1995-07-11 1998-03-17 Valmet Paperikoneet Inc. Method and apparatus for sharpening the surface of a grindstone for a pulp grinder
WO2000073571A1 (fr) * 1999-05-26 2000-12-07 Tom Forsman Procede de commande d'une operation de reduction de bois en pate mecanique
CN110293482A (zh) * 2019-07-05 2019-10-01 湖南科技大学 一种圆弧形金刚石砂轮的修锐方法

Also Published As

Publication number Publication date
DE4292499T1 (de) 1994-06-09
JPH07500775A (ja) 1995-01-26
AU2368592A (en) 1993-03-02
FI88938B (fi) 1993-04-15
SE503135C2 (sv) 1996-04-01
FI88938C (fi) 1993-07-26
GB9402153D0 (en) 1994-04-13
FI913803L (fi) 1993-02-10
SE9400424D0 (sv) 1994-02-09
FI913803A0 (fi) 1991-08-09
GB2274079B (en) 1995-05-10
SE9400424L (sv) 1994-02-09
GB2274079A (en) 1994-07-13

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