CA2089197A1 - Method and arrangement for fastening a grinding segment - Google Patents
Method and arrangement for fastening a grinding segmentInfo
- Publication number
- CA2089197A1 CA2089197A1 CA 2089197 CA2089197A CA2089197A1 CA 2089197 A1 CA2089197 A1 CA 2089197A1 CA 2089197 CA2089197 CA 2089197 CA 2089197 A CA2089197 A CA 2089197A CA 2089197 A1 CA2089197 A1 CA 2089197A1
- Authority
- CA
- Canada
- Prior art keywords
- grinding
- fastening
- base plate
- frame
- segment
- 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.)
- Abandoned
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
- B24D7/00—Bonded abrasive wheels, or wheels with inserted abrasive blocks, designed for acting otherwise than only by their periphery, e.g. by the front face; Bushings or mountings therefor
- B24D7/06—Bonded abrasive wheels, or wheels with inserted abrasive blocks, designed for acting otherwise than only by their periphery, e.g. by the front face; Bushings or mountings therefor with inserted abrasive blocks, e.g. segmental
- B24D7/066—Grinding blocks; their mountings or supports
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Polishing Bodies And Polishing Tools (AREA)
- Debarking, Splitting, And Disintegration Of Timber (AREA)
- Paper (AREA)
Abstract
Abstract A method and arrangement for fastening a grinding seg-ment (2) to the frame (1a) of a grindstone, and a grind-ing segment.
The grinding part (3) of the grinding segment (2) is attached to a separate base plate (4) by means of fas-tening mass (5), which is advantageously made of con-crete. The grinding segment (2) is fastened to the frame (1a) of a grindstone by bolts or other fastening means (6) such that the fastening force of the grinding seg-ment affects only the metallic base plate (4) of the grinding segment and that the forces between the frame of the grindstone and the ceramic grinding part are transmitted only through the fastening mass (5).
(Fig. 2)
The grinding part (3) of the grinding segment (2) is attached to a separate base plate (4) by means of fas-tening mass (5), which is advantageously made of con-crete. The grinding segment (2) is fastened to the frame (1a) of a grindstone by bolts or other fastening means (6) such that the fastening force of the grinding seg-ment affects only the metallic base plate (4) of the grinding segment and that the forces between the frame of the grindstone and the ceramic grinding part are transmitted only through the fastening mass (5).
(Fig. 2)
Description
~ 0(~,t~
Method and arrangement for fastening a grinding segment The invention relates to a method of fastening a grinding segment comprising a ceramic grinding part 5to the frame of a grinding elPment to be used for the production of machanical pulp, wherein the grinding segment is pressed against the frame by at least one fastening means arranged between the grinding segmen~
and the frame.
10The invention also relates to an arrangement for fastening a grinding segment comprising a ceramic grinding part to the frame of a grinding element to be used for the production of mechanical pulp, wherein the grinding segment is pressed against the frame by at 15least one fastening means arranged between the grindiny segment and the frame.
The invention further relates to a grinding segment comprising a ceramic grinding part for the grinding element of a pulp grinder.
20Groundwood is produced in a known manner by pressing the log against the rotating grinding element, i.e. the grindstone, by a loading apparatus, e.g. a hydraulic cylinder. By grinding techniques is also pro-duced mechanical pulp by supplying wood chips between 25the grinding surfaces. The grinding element is cooled from the outside by means of water jets. The rotating grinding element has conventionally been a grindstone.
Earlier, natural or concrete stones were used but today chiefly ceramic materials are used. Ceramic segments 30generally used as grinding elements are usually fastened either to a reinforced concrete frame or to a metal cylinder frame by fastening means. The problem with the now used solutions disclosed e.g. in U.S. Patents 2,421,885, 2,745,226, 3,227,611 and 2,768,286 is the 35different coefficient of heat expansion of the segment ~$~
and of the fastening bolt used as the fastening means.
This causes loosening of the segments when the tempera-ture of the grindstone rises from the mounting tempera-ture to the use temperature if the bolts have not been pre-ti~htened sufficiently firmly. The use temperatures of the present pressure grinders have risen. This causes even more problems in -fastening the grinding segments since the coefficient of heat expansion of iron is about twice as high as the coefficient of heat expansion of ceramic materials. In present constructions the prohlem is solved by pre-tightening the fastening bolts to com-pensate for the loosening caused by the centrifugal force and the difference in the heat expansion. However, this brings about great internal stress in the segment already in the assemby step, ~he stress later often resul-ting in cracking and loosening of the segment when the stone is used.
Further, Finnish Paten-t Application 831,A30 discloses a solu-tion where problems occurring in fasten-ing the grinding segment are resolved by positioning a bushing between the bolt and the frame, the bushing having such heat expansion properties that the heat expansion properties of the bolt and those of the bush ing compensate for each o-ther, maintaining the tighten~
ing force essentially as constant. In some cases the use of this solution requires that the frame of the grind-stone has a specific structure and that it is possible.
to reach inside it. However, this is not always possible and therefore is may be difficult, although not imposs-ible, in some cases to apply this solution.
The object of the present invention is to pro-vide a method of fastening a grinding segment to a grinding element, particularly to a grindstone, an~:l correspondingly, an arrangement for fastening a grinding ~egment to a grinding element, partisularly to a grind-. ~$9~97 stone, and a grinding segment by which the above-men-tioned problems are avoided and by ~hich the grinding element can be fastened in a simple and reliable manner.
It is charactexistic of the method of the invention that the ceramic grinding part is fastened b~ means of ~s-tening mass to a separate base plate made o metal and that ~he fastening means is arranged to press the grind-ing segment consisting of a ceramic part, a ~ase plate and fastening mass between them against the frame of the grinding element only through the metallic base plate such that the forces between the frame and the ceramic grinding part are transmitted essentially through the fastening mass.
The arrangement according to the invention is characterised in that the grinding segment consists of a ceramic grinding part and a metallic base plate attached to each other by means of fastening mass, that the grinding segment is fastened to the frame of the grinding element by fastening means securing only the metallic base plate to the frame of-the grinding element such that all forces between ~he ceramic grinding part and the frame of the grinding element are transmitted essentially through the fastening mass.
The grinding segment according to the invention is characterised in that the grindin~ segment comprises a separate ceramic grinding part and a metallic base plate for it, that the grinding part and the base plate are attached to each othar only by means of astening mass and that the fastening means for fastening the grinding segment to the frame of the grinding element may be secured only to the base plate such that all forces between the ceramic grinding part and the frame of thP grinding element are transmitted through the fastening mass.
The essential feature of the invention is that the ceramic grinding part of the grinding segment is attached to the me-tallic base plate by concrete or other suitable fastening mass such that the ceramic grindiny part is attached only to the metallic base plate, the grinding segment consisting of a metallic base plate, fastening mass and a ceramic grinding part fastened to the frame of the grindstone by fastening means, such as bolts or nuts, extending through the me-tallic base plate.
The radial forces affecting the grinding seg-ment load only the metallic base plate'without subject-ing the ceramic grinding part to any kind of radial compression load or concentrated load that mi~ht ~rack it. The forces produced during the grinding between the frame and the ceramic grinding part are transmitted only through the fastening mass. The advantage of the struc-ture according to the invention is that, if necessary, the grinding segment can be replaced easily and simply since no support mass ~astening the segment irmly to its place is needed between the grinding segments and the frame or between adjacent grinding segments. Thus a segment can be replaced quickly while the grindstone is in place in the grinder, whereas in the known tech-niques the grindstone often has to be removed from the grinder for the replacement of the segment. Thus, both time and work are saved by the solution of the invention and therefore the costs are also considerably lower.
The invention is described in greater detail in the attached drawings, wherein Fig. l shows a schematic view of the grindstone according to the invention seen from the direction of the axle, ~ ~ $ ,~ 7 Fig. 2 shows a schematic view of the cross-section of the grinding segment according to the inven-tion fastened to the grindstone, Fig. 3 shows a schematic view of the joint surface of the ceramic grinding part in the grinding segment according to Fig. 1, Figs. 4a and 4b show a schematic vizw of another joint surface of the ceramic part of the grind-ing segment according to the invention.
Fig. 1 shows a schematic view of a grindstone 1, around which are fastened grinding segments 2. A
frame la of the grindstone 1 is given the form of a polygon such that at each face are fastened grinding segments 2 such that they form a circular grinding sur-face 2a around the grindstone 1. The frame la of the grindstone 1 may be made of metal, concrete or o-ther suitable material. When the frame is not made of metal, suitable fastening means, such as bolts or nuts, are secured thereto in one way or another to fasten the grinding segments 2 in place.
Fig. 2 shows the cross-section of the grinding segmen~ 2 presented schematically in Fig. 1 along the line A - A indicated in Fig. 3 such that it shows both the structure of the grinding segment 2 and the way it is fastened to the frame la of the grindstone 1. Fig.
2 shows a ceramic grinding part 3 forming the grinding surface of the grinding segment, the outer surface of the grinding part being curved and having an aperture 3a through which the grinding segment 2 can be fastened to the frame la of the grindstone. In addition, the grinding segment 2 comprises a metallic base plate 4, which is nearest to the rame la of the grindstone. The ceramic surface layer and the metallic base plate 4 are attached to each other by means of fastening mass 5 between them, the mass attaching the grinding part to : ~ ... , ~ . ...
h ~ ~3 p~
the base plate 4. To strengthsn the joint, the ceramic grinding part 3 comprises slots or grooves 3b into which the fastening mass 5 penetrates. The metallic base plate 4 further comprises, or to it are fastened, support means 4a extending to the slots 3b of the grinding part 3 and thereby strengthening the joint. Further, the metallic base plate 4 advantageously has slots or grooves 4b into which the fastening mass 5 is capable of penetrating in the same manner as into the slots or grooves 3b of the surface layer 3, the sufficiently load-enduring fastening mass 5, advantageously concrete, firmly attaching the grinding part 3'to the base plate 4, thereby forming a grinding segment with them. To fasten the grinding segment, the base plate 4 is pro-vided with apertures, a bolt 6 being driveable through the apertures to the threads of the frame la. In order that it might be possible to drive the bolt 6, a bolt sleeve 7 is arranged at the aperture 3a of the grinding part 3 in connection with the casting, the bolt sleeve preventing the fastening mass 5 from penetrating into the aperture 3a and keeping the corresponding part of the base plate 4 clear of fastening mass. Thus, a grind-ing segment 2 may be fastened simply by pushing a bolt 6 through each aperture 3a and firmly ti~htening the base plate 4 to the frame la of the grindstone by bolts.
The advantage of the present solution is that the entire joint surface of the ceramic part of the grinding segment 2 is affected by fastening force brought about by the fastening mass, the fastening force being distributed evenly without any load peaks or con-centrated loads of any kind in the ceramic part. The loads between the ceramic grinding part 3 and the frame la of the grindstone that occur during the grinding, i.e. the peripheral shearing force and the radial com-. . .
pression force, are in pr~ctice transmitted entirely through the fastening mass, whereby they are distributed essentially evenly to the entire grinding segment. If one or some of the supporting means 4a or the like of the metallic base plate 4 are in contact with the ceramic grinding part 3, this has no essential signifi-cance in respect of the transmission of the ~orce and therefore it does not affect the essential idea of the invention. This signific~n-tly decreases the risk that the ceramic grinding part might break since even load also prevents cracking caused by fragility of ceramics when the load is great. In additionl, when a metal frame is used in fastening a grinding segment, the joint used s a metal to metal joint, which is at present mastered ~,echnically fairly well and in which heat expansion can be controlled without allowing it to affect the ceramic grinding part 3 in any way. Unlike in the known art, this joining method does not demand putty between the grinding segment 2 and the frame la of the grindstone, nor between adjacent grinding segments 2, wherehy the grinding segment is fastened only by means of bolts 6 and the segment can be easily removed by undriving the bolts 6 without touching the adjoining segments or breaking the grinding segment into pieces, as often has to be done in the prior art solutions. Thereby the grinding segment can be replaced mer~ly by undriving the bolts. ~his can be done in a fairly short time during a momentary stop of the grinder while the grindstone remains in place in the grinder. When the segment has been replaced, a new segment is ground to make it simi-lar to the other segments, which is also fairly quick to carry out. Thus the replacement of the grinding seg-ment can he completed in a fairly short time.
Fig. 3 shows the ceramic grinding part 3 of the grinding segment according to Fig. 2 seen from below in the direction of the joint surface. As shown in Fig. 3, on-to the bottom surface of the ceramic grinding part are made primarily circular slots 3b into which the fas-ten-ing mass penetrates during the casting, the support means 4a shown in Fig. 2 extending inside the slots.
Fig. 3 shows several slots 3b, some of the slots extend-ing to the edge of the grinding part 3 in order that too thin ceramic pieces that crack easily might not be formed. In segments of the normally used sizes, a smaller number of slots 3b is sufficient, e.g. six to seven slots being a suitable or advantageous number.
However, the form and size of the slots has to be selected in accordance with the size, surface area and other dimensions of the grinding segment to be used.
In the embodiment of the invention described in Figs. 4a and 4b, separate slots are replaced by sev-eral unbroken grooves or the like forming a regular uneven surface and thereby adding to the joint surface available to the fastening mass such that a joint sur-face producing a sufficiently great shearing force is provided between the part and the fastening mass. In a corresponding manner, the surface of the metallic base plate 4 can be grooved such that the patterns in the grinding part 3 and those in the base plate 4 partly intermesh, whereby fairly thin layers of fastening mass can be used. In the embodiment of Figs. 4a and 4b, the surfaces comprise e.g. diagonal grooves and ridges sur-rounding the center point of the grinding segment in a circle. This kind of structure is easy to manufacture and can be simply and easily strengthened and supported in different ways.
The method and arrangement according to the invention can be carried out in several different ways, whereby grinding segments with conventional dimensions and a similar grinding surface on -the outside can be 2~$~;9 ~
used in the production of a grindstone both in the axial direction of the grindstone and in the radial direction of the grindstone. Howevèr, according to the invention it is also possible to produce a ~rindstone by usin~
longer grinding segments, whereby a grinding segment may even extend from one edge of the grindstone to the other in the axial direction, whereby in^termeshing of segments, which is used in the present technology, is not necessary. Further, the segments, always at least two successive segments in the axial direction of the grindstone, can be made longer than they are at present, whereby a smaller part of the s~rface of the grindstone has to be replaced in case of cracking but the replace-ment can be performed as quickly in the present inven-tion as with grinding segments formed in accordance with the prior art. The fastening mass may be made o con-crete, which is often a fairly advantageous material both in respect of the strength properties and the heat conduct and durability. In addition, several other fas~
tening materials can be used, such as furan resin or other suitable adhesives or fastening masses having strength and flexibility that suit the purpose and suf-fici~nt chemical durability and heat endurance. Althou~h it is stated above that the base plate oE the grinding segment is even, since the presently known grinding elements have planar joint surfaces, the grinding seg-ment of the invention may also have a curving surface on the side of the frame of the grindstone, whereby the frame of the grindstone can be made circular and the grinding segments can be tightened against the curving surface. Likewise, the grinding segments may be fastened not only by bolt joints or the like but also in some other manner, e.gO by using key slot joints or other corresponding solutions whenever it is possible in respect of the structure of the frame of the grindstone.
s~ 7 For example, it is possible to use a solution with a wedge-like counterpart at one edge of the grinding seg-ment, the coun~erpart fitting into the wedge-like slot in the frame of the grindstone, whereby one part of the grinding segment can be -tightened to its place e.g. by means of a bolt joint or the like or by using a separate wedge-like tightening body that is tightened to its place by bolts or the like. In addition to -the above embodiment useable in connection with a grindstone, the invention can also be used in other grinding elements in which a ceramic grinding surface is used for produc-ing mechanical pulp. '-
Method and arrangement for fastening a grinding segment The invention relates to a method of fastening a grinding segment comprising a ceramic grinding part 5to the frame of a grinding elPment to be used for the production of machanical pulp, wherein the grinding segment is pressed against the frame by at least one fastening means arranged between the grinding segmen~
and the frame.
10The invention also relates to an arrangement for fastening a grinding segment comprising a ceramic grinding part to the frame of a grinding element to be used for the production of mechanical pulp, wherein the grinding segment is pressed against the frame by at 15least one fastening means arranged between the grindiny segment and the frame.
The invention further relates to a grinding segment comprising a ceramic grinding part for the grinding element of a pulp grinder.
20Groundwood is produced in a known manner by pressing the log against the rotating grinding element, i.e. the grindstone, by a loading apparatus, e.g. a hydraulic cylinder. By grinding techniques is also pro-duced mechanical pulp by supplying wood chips between 25the grinding surfaces. The grinding element is cooled from the outside by means of water jets. The rotating grinding element has conventionally been a grindstone.
Earlier, natural or concrete stones were used but today chiefly ceramic materials are used. Ceramic segments 30generally used as grinding elements are usually fastened either to a reinforced concrete frame or to a metal cylinder frame by fastening means. The problem with the now used solutions disclosed e.g. in U.S. Patents 2,421,885, 2,745,226, 3,227,611 and 2,768,286 is the 35different coefficient of heat expansion of the segment ~$~
and of the fastening bolt used as the fastening means.
This causes loosening of the segments when the tempera-ture of the grindstone rises from the mounting tempera-ture to the use temperature if the bolts have not been pre-ti~htened sufficiently firmly. The use temperatures of the present pressure grinders have risen. This causes even more problems in -fastening the grinding segments since the coefficient of heat expansion of iron is about twice as high as the coefficient of heat expansion of ceramic materials. In present constructions the prohlem is solved by pre-tightening the fastening bolts to com-pensate for the loosening caused by the centrifugal force and the difference in the heat expansion. However, this brings about great internal stress in the segment already in the assemby step, ~he stress later often resul-ting in cracking and loosening of the segment when the stone is used.
Further, Finnish Paten-t Application 831,A30 discloses a solu-tion where problems occurring in fasten-ing the grinding segment are resolved by positioning a bushing between the bolt and the frame, the bushing having such heat expansion properties that the heat expansion properties of the bolt and those of the bush ing compensate for each o-ther, maintaining the tighten~
ing force essentially as constant. In some cases the use of this solution requires that the frame of the grind-stone has a specific structure and that it is possible.
to reach inside it. However, this is not always possible and therefore is may be difficult, although not imposs-ible, in some cases to apply this solution.
The object of the present invention is to pro-vide a method of fastening a grinding segment to a grinding element, particularly to a grindstone, an~:l correspondingly, an arrangement for fastening a grinding ~egment to a grinding element, partisularly to a grind-. ~$9~97 stone, and a grinding segment by which the above-men-tioned problems are avoided and by ~hich the grinding element can be fastened in a simple and reliable manner.
It is charactexistic of the method of the invention that the ceramic grinding part is fastened b~ means of ~s-tening mass to a separate base plate made o metal and that ~he fastening means is arranged to press the grind-ing segment consisting of a ceramic part, a ~ase plate and fastening mass between them against the frame of the grinding element only through the metallic base plate such that the forces between the frame and the ceramic grinding part are transmitted essentially through the fastening mass.
The arrangement according to the invention is characterised in that the grinding segment consists of a ceramic grinding part and a metallic base plate attached to each other by means of fastening mass, that the grinding segment is fastened to the frame of the grinding element by fastening means securing only the metallic base plate to the frame of-the grinding element such that all forces between ~he ceramic grinding part and the frame of the grinding element are transmitted essentially through the fastening mass.
The grinding segment according to the invention is characterised in that the grindin~ segment comprises a separate ceramic grinding part and a metallic base plate for it, that the grinding part and the base plate are attached to each othar only by means of astening mass and that the fastening means for fastening the grinding segment to the frame of the grinding element may be secured only to the base plate such that all forces between the ceramic grinding part and the frame of thP grinding element are transmitted through the fastening mass.
The essential feature of the invention is that the ceramic grinding part of the grinding segment is attached to the me-tallic base plate by concrete or other suitable fastening mass such that the ceramic grindiny part is attached only to the metallic base plate, the grinding segment consisting of a metallic base plate, fastening mass and a ceramic grinding part fastened to the frame of the grindstone by fastening means, such as bolts or nuts, extending through the me-tallic base plate.
The radial forces affecting the grinding seg-ment load only the metallic base plate'without subject-ing the ceramic grinding part to any kind of radial compression load or concentrated load that mi~ht ~rack it. The forces produced during the grinding between the frame and the ceramic grinding part are transmitted only through the fastening mass. The advantage of the struc-ture according to the invention is that, if necessary, the grinding segment can be replaced easily and simply since no support mass ~astening the segment irmly to its place is needed between the grinding segments and the frame or between adjacent grinding segments. Thus a segment can be replaced quickly while the grindstone is in place in the grinder, whereas in the known tech-niques the grindstone often has to be removed from the grinder for the replacement of the segment. Thus, both time and work are saved by the solution of the invention and therefore the costs are also considerably lower.
The invention is described in greater detail in the attached drawings, wherein Fig. l shows a schematic view of the grindstone according to the invention seen from the direction of the axle, ~ ~ $ ,~ 7 Fig. 2 shows a schematic view of the cross-section of the grinding segment according to the inven-tion fastened to the grindstone, Fig. 3 shows a schematic view of the joint surface of the ceramic grinding part in the grinding segment according to Fig. 1, Figs. 4a and 4b show a schematic vizw of another joint surface of the ceramic part of the grind-ing segment according to the invention.
Fig. 1 shows a schematic view of a grindstone 1, around which are fastened grinding segments 2. A
frame la of the grindstone 1 is given the form of a polygon such that at each face are fastened grinding segments 2 such that they form a circular grinding sur-face 2a around the grindstone 1. The frame la of the grindstone 1 may be made of metal, concrete or o-ther suitable material. When the frame is not made of metal, suitable fastening means, such as bolts or nuts, are secured thereto in one way or another to fasten the grinding segments 2 in place.
Fig. 2 shows the cross-section of the grinding segmen~ 2 presented schematically in Fig. 1 along the line A - A indicated in Fig. 3 such that it shows both the structure of the grinding segment 2 and the way it is fastened to the frame la of the grindstone 1. Fig.
2 shows a ceramic grinding part 3 forming the grinding surface of the grinding segment, the outer surface of the grinding part being curved and having an aperture 3a through which the grinding segment 2 can be fastened to the frame la of the grindstone. In addition, the grinding segment 2 comprises a metallic base plate 4, which is nearest to the rame la of the grindstone. The ceramic surface layer and the metallic base plate 4 are attached to each other by means of fastening mass 5 between them, the mass attaching the grinding part to : ~ ... , ~ . ...
h ~ ~3 p~
the base plate 4. To strengthsn the joint, the ceramic grinding part 3 comprises slots or grooves 3b into which the fastening mass 5 penetrates. The metallic base plate 4 further comprises, or to it are fastened, support means 4a extending to the slots 3b of the grinding part 3 and thereby strengthening the joint. Further, the metallic base plate 4 advantageously has slots or grooves 4b into which the fastening mass 5 is capable of penetrating in the same manner as into the slots or grooves 3b of the surface layer 3, the sufficiently load-enduring fastening mass 5, advantageously concrete, firmly attaching the grinding part 3'to the base plate 4, thereby forming a grinding segment with them. To fasten the grinding segment, the base plate 4 is pro-vided with apertures, a bolt 6 being driveable through the apertures to the threads of the frame la. In order that it might be possible to drive the bolt 6, a bolt sleeve 7 is arranged at the aperture 3a of the grinding part 3 in connection with the casting, the bolt sleeve preventing the fastening mass 5 from penetrating into the aperture 3a and keeping the corresponding part of the base plate 4 clear of fastening mass. Thus, a grind-ing segment 2 may be fastened simply by pushing a bolt 6 through each aperture 3a and firmly ti~htening the base plate 4 to the frame la of the grindstone by bolts.
The advantage of the present solution is that the entire joint surface of the ceramic part of the grinding segment 2 is affected by fastening force brought about by the fastening mass, the fastening force being distributed evenly without any load peaks or con-centrated loads of any kind in the ceramic part. The loads between the ceramic grinding part 3 and the frame la of the grindstone that occur during the grinding, i.e. the peripheral shearing force and the radial com-. . .
pression force, are in pr~ctice transmitted entirely through the fastening mass, whereby they are distributed essentially evenly to the entire grinding segment. If one or some of the supporting means 4a or the like of the metallic base plate 4 are in contact with the ceramic grinding part 3, this has no essential signifi-cance in respect of the transmission of the ~orce and therefore it does not affect the essential idea of the invention. This signific~n-tly decreases the risk that the ceramic grinding part might break since even load also prevents cracking caused by fragility of ceramics when the load is great. In additionl, when a metal frame is used in fastening a grinding segment, the joint used s a metal to metal joint, which is at present mastered ~,echnically fairly well and in which heat expansion can be controlled without allowing it to affect the ceramic grinding part 3 in any way. Unlike in the known art, this joining method does not demand putty between the grinding segment 2 and the frame la of the grindstone, nor between adjacent grinding segments 2, wherehy the grinding segment is fastened only by means of bolts 6 and the segment can be easily removed by undriving the bolts 6 without touching the adjoining segments or breaking the grinding segment into pieces, as often has to be done in the prior art solutions. Thereby the grinding segment can be replaced mer~ly by undriving the bolts. ~his can be done in a fairly short time during a momentary stop of the grinder while the grindstone remains in place in the grinder. When the segment has been replaced, a new segment is ground to make it simi-lar to the other segments, which is also fairly quick to carry out. Thus the replacement of the grinding seg-ment can he completed in a fairly short time.
Fig. 3 shows the ceramic grinding part 3 of the grinding segment according to Fig. 2 seen from below in the direction of the joint surface. As shown in Fig. 3, on-to the bottom surface of the ceramic grinding part are made primarily circular slots 3b into which the fas-ten-ing mass penetrates during the casting, the support means 4a shown in Fig. 2 extending inside the slots.
Fig. 3 shows several slots 3b, some of the slots extend-ing to the edge of the grinding part 3 in order that too thin ceramic pieces that crack easily might not be formed. In segments of the normally used sizes, a smaller number of slots 3b is sufficient, e.g. six to seven slots being a suitable or advantageous number.
However, the form and size of the slots has to be selected in accordance with the size, surface area and other dimensions of the grinding segment to be used.
In the embodiment of the invention described in Figs. 4a and 4b, separate slots are replaced by sev-eral unbroken grooves or the like forming a regular uneven surface and thereby adding to the joint surface available to the fastening mass such that a joint sur-face producing a sufficiently great shearing force is provided between the part and the fastening mass. In a corresponding manner, the surface of the metallic base plate 4 can be grooved such that the patterns in the grinding part 3 and those in the base plate 4 partly intermesh, whereby fairly thin layers of fastening mass can be used. In the embodiment of Figs. 4a and 4b, the surfaces comprise e.g. diagonal grooves and ridges sur-rounding the center point of the grinding segment in a circle. This kind of structure is easy to manufacture and can be simply and easily strengthened and supported in different ways.
The method and arrangement according to the invention can be carried out in several different ways, whereby grinding segments with conventional dimensions and a similar grinding surface on -the outside can be 2~$~;9 ~
used in the production of a grindstone both in the axial direction of the grindstone and in the radial direction of the grindstone. Howevèr, according to the invention it is also possible to produce a ~rindstone by usin~
longer grinding segments, whereby a grinding segment may even extend from one edge of the grindstone to the other in the axial direction, whereby in^termeshing of segments, which is used in the present technology, is not necessary. Further, the segments, always at least two successive segments in the axial direction of the grindstone, can be made longer than they are at present, whereby a smaller part of the s~rface of the grindstone has to be replaced in case of cracking but the replace-ment can be performed as quickly in the present inven-tion as with grinding segments formed in accordance with the prior art. The fastening mass may be made o con-crete, which is often a fairly advantageous material both in respect of the strength properties and the heat conduct and durability. In addition, several other fas~
tening materials can be used, such as furan resin or other suitable adhesives or fastening masses having strength and flexibility that suit the purpose and suf-fici~nt chemical durability and heat endurance. Althou~h it is stated above that the base plate oE the grinding segment is even, since the presently known grinding elements have planar joint surfaces, the grinding seg-ment of the invention may also have a curving surface on the side of the frame of the grindstone, whereby the frame of the grindstone can be made circular and the grinding segments can be tightened against the curving surface. Likewise, the grinding segments may be fastened not only by bolt joints or the like but also in some other manner, e.gO by using key slot joints or other corresponding solutions whenever it is possible in respect of the structure of the frame of the grindstone.
s~ 7 For example, it is possible to use a solution with a wedge-like counterpart at one edge of the grinding seg-ment, the coun~erpart fitting into the wedge-like slot in the frame of the grindstone, whereby one part of the grinding segment can be -tightened to its place e.g. by means of a bolt joint or the like or by using a separate wedge-like tightening body that is tightened to its place by bolts or the like. In addition to -the above embodiment useable in connection with a grindstone, the invention can also be used in other grinding elements in which a ceramic grinding surface is used for produc-ing mechanical pulp. '-
Claims (10)
1. A method of fastening a grinding segment comprising a ceramic grinding part to the frame of a grinding element to be used for the production of mechanical pulp, wherein the grinding segment is pressed against the frame by at least one fastening means arranged between the grinding segment and the frame and wherein the ceramic grinding part is fastened by means of fastening mass to a separate base plate made of metal and the fastening means is arranged to press the grind-ing segment consisting of a ceramic part, a base plate and fastening mass therebetween against the frame of the grinding element only through the metallic base plate such that the forces between the frame and the ceramic grinding part are transmitted essentially through the fastening mass.
2. A method according to claim 1, wherein onto the joint surface of the ceramic grinding part are made slots or grooves and, correspondingly, onto the joint surface of the base plate are formed slots or grooves before they are attached to each other by fastening mass so as to increase the surface area and fastening strength of the joint surfaces.
3. A method according to claim 2, wherein to the base plate are formed or secured support means, which in the finished grinding segment extend into the slots of the ceramic grinding part.
4. A method according to claim 1, wherein the ceramic grinding part is attached to the base plate by means of fastening mass made of concrete.
5. An arrangement for fastening a grinding segment comprising a ceramic grinding part to the frame of a grinding element to be used for the production of mechanical pulp, wherein the grinding segment is pressed against the frame by at least one fastening means arranged between the grinding segment and the frame and wherein the grinding segment consists of a ceramic grinding part and a metallic base plate attached to each other by means of fastening mass and the grinding segment is fastened to the frame of the grinding element by fastening means securing the metallic base plate to the frame of the grinding element such that the forces between the ceramic grinding part and the frame of the grinding element are transmitted essentially through the fastening mass.
6. An arrangement according to claim 5, wherein onto the joint surface of the ceramic grinding part are made slots or grooves and, correspondingly, onto the joint surface of the base plate are formed slots or grooves to increase the surface area and fastening strength of the joint surfaces of the fastening mass.
7. An arrangement according to claim 6, wherein to the base plate are formed or secured support means, which in the finished grinding segment extend into the slots of the ceramic grinding part.
8. An arrangement according to claim 5, wherein the ceramic grinding part is attached to the base plate by means of fastening mass made of concrete.
9. An arrangement according to claim 5, wherein the fastening means are bolts or the like known per se, the bolts being arranged to extend through apertures or holes formed in the base plate and pressing the base plate against the surface of the frame.
10. A grinding segment comprising a ceramic grinding part for the grinding element of a pulp grinder, the grinding segment further comprising a metallic base plate, whereby the grinding part and the base plate are attached to each other only by means of fastening mass and the fastening means for fastening the grinding segment to the frame of the grinding element may be secured only to the base plate such that the forces between the ceramic grinding part and the frame of the grinding element are transmitted through the fastening mass.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI920665A FI89515C (en) | 1992-02-14 | 1992-02-14 | FARING SENSOR FOR SUSPENSION OF SLIPSEGMENT SAMT SLIPSEGMENT |
| FI920665 | 1992-02-14 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2089197A1 true CA2089197A1 (en) | 1993-08-15 |
Family
ID=8534662
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2089197 Abandoned CA2089197A1 (en) | 1992-02-14 | 1993-02-10 | Method and arrangement for fastening a grinding segment |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPH07252789A (en) |
| CA (1) | CA2089197A1 (en) |
| DE (1) | DE4304128A1 (en) |
| FI (1) | FI89515C (en) |
| NO (1) | NO930439L (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2741560B1 (en) * | 1995-11-23 | 1998-02-06 | Briot Int | IMPROVED GRINDER FOR OPHTHALMIC LENSES, AND CORRESPONDING GRINDING MACHINE |
| FI110520B (en) | 2001-03-16 | 2003-02-14 | Metso Paper Inc | Grinding elements and grinding stones |
-
1992
- 1992-02-14 FI FI920665A patent/FI89515C/en not_active IP Right Cessation
-
1993
- 1993-02-09 NO NO93930439A patent/NO930439L/en unknown
- 1993-02-10 CA CA 2089197 patent/CA2089197A1/en not_active Abandoned
- 1993-02-11 DE DE19934304128 patent/DE4304128A1/en not_active Withdrawn
- 1993-02-15 JP JP4865593A patent/JPH07252789A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JPH07252789A (en) | 1995-10-03 |
| DE4304128A1 (en) | 1993-08-19 |
| NO930439D0 (en) | 1993-02-09 |
| FI920665A0 (en) | 1992-02-14 |
| NO930439L (en) | 1993-08-16 |
| FI89515B (en) | 1993-06-30 |
| FI89515C (en) | 1993-10-11 |
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| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |