CA2096272A1 - Refiner plate segments - Google Patents
Refiner plate segmentsInfo
- Publication number
- CA2096272A1 CA2096272A1 CA 2096272 CA2096272A CA2096272A1 CA 2096272 A1 CA2096272 A1 CA 2096272A1 CA 2096272 CA2096272 CA 2096272 CA 2096272 A CA2096272 A CA 2096272A CA 2096272 A1 CA2096272 A1 CA 2096272A1
- Authority
- CA
- Canada
- Prior art keywords
- rotor
- plate segments
- face
- refiner
- 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
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21D—TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
- D21D1/00—Methods of beating or refining; Beaters of the Hollander type
- D21D1/20—Methods of refining
- D21D1/30—Disc mills
- D21D1/306—Discs
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21D—TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
- D21D1/00—Methods of beating or refining; Beaters of the Hollander type
- D21D1/20—Methods of refining
- D21D1/30—Disc mills
Landscapes
- Paper (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
An apparatus for processing fibrous materials having at least one rotor with a rotor face and rotor plate segments adapted to be mounted on said rotor face, said rotor adapted to turn at a differential speed relative to adjacent plate segments; the invention comprising an included angle at the surface of contact between the rotor plate segments and the rotor face such that centrifugal forces acting on the rotor plate segments will tend to force each plate segment against the face of the rotor.
An apparatus for processing fibrous materials having at least one rotor with a rotor face and rotor plate segments adapted to be mounted on said rotor face, said rotor adapted to turn at a differential speed relative to adjacent plate segments; the invention comprising an included angle at the surface of contact between the rotor plate segments and the rotor face such that centrifugal forces acting on the rotor plate segments will tend to force each plate segment against the face of the rotor.
Description
2~272 REFINER PLATE SEGMENTS
The present invention relates to refiners used to grind fibrous materials such as wood pulps. The working surfaces of refiners are typically comprised of bars and grooves of different configurations which vary depending on the type of material to be processed. The working surfaces are subject to wear and therefore they are designed to be replaceable. Typically, the surfaces in a mechanical pulping re~iner for wood chips require replacement about four times per year.
It has been conventional practice to manufacture the replaceable working surfaces in segments of an annulus which are then mounted in the refiner with mechanical means. The most common method of mounting is to place each segment against a rim near the outside diameter in order to locate the segment radially and then to attach the segment in place using one or more fasteners such as bolts.
At least one of the working surfaces is in rotation, and the rotating refiner plate segments are subjected to centrifugal forces. In large refiners, these forces can exceed fifty tons per segment. These forces may cause large stresses in the segments and in the rotor to which they are attached. Decreasing the weight of the segments reduces these forces however, with conventional bolting methods, the thickness of the plate segments is often a function cf the physical dimension of the bolts used. In addition, a conventional plate . .
20~272 segment must have a section modulus and moment of inertia sufficient to resist a large bending moment. This bending moment is caused because the line of action of the centrifugal force acting on the segment is not in line with the restraining force of the rotor rim. For conventional plates it is difficult to increase the width of the rotor rim in order that these force lines coincide without inducing very high bending stresses in the rotor itself.
The thickness and weight of conventional plates can be considered close to the optimum as a result of years of experience and development by many different manufacturers. Conventional plates are usually stressed in both compression and tension due to the bending moment described above. The materials used for these plate segments are typically very hard and brittle and in most cases it is preferable to reduce or avoid tensile stresses in these materials. Conventional plate designs preclude the use of many new ceramic materials due to these tensile stresses. Another disadvantage of some conventional plate segment mounting methods is that the bolting may affect the refining action in the fine bar section at the outer portion of the refining zone. A
further consideration in the method of plate segment mounting is the ease of replacement. Conventional plates are heavy to manipulate, require many bolts and worn plates may be difficult to remove due to damage of the 209~27~
bolt heads. A still further consideration is safety.
Conventional plates rely on bolts to restrain them. Bolt failures due to breakage or loosening can result in plate segments flying off the rotor. In addition, great care must be taken in manufacturing to avoid material defects which could cause the refiner plate segments to crack under the influence of tensile stresses.
The present invention has been developed to overcome the limitations of conventional refiner plate segments. A first object of the invention is to reduce the weight of the refiner plate segments. A second object of the invention is to minimize tensile stresses in the plate segments. A third object of the invention is to facilitate the changing of plate segments. A
fourth object of the invention is to provide a "fail-safe" retention of the segments on the rotor. A fifth object of the invention is to avoid process disturbances in the refining zone. A sixth object of the invention is to reduce the stress in the vicinity of the rim of the refiner rotor.
One embodiment of the invention relates to an apparatus for processing fibrous materials having at least one rotor with a rotor face and rotor plate segments adapted to be mounted on said rotor face, said rotor adapted to turn at a differential speed relative to adjacent plate segments, the invention comprising an included angle at the surface of contact between the - ~ . . , - ,. ~
: ' :
, : , .
' , : ' ' ' rotor plate segments and the rotor face such that centrifugal forces acting on the rotor plate segments will tend to force each plate segment against the face of the rotor.
In another aspect the invention relates to an apparatus for processing fibrous materials having at least one rotor with a rotor face and rotor plate segments adapted to be mounted on said rotor face, in which the plate segments are restrained by means of a rim on the rotor; the rim being characterized by a contact angle with the refiner plate segments of less than 85 such that resultant force at the rim due to the combination of centrifugal loading and contact friction will tend to force the plate segments against the face of the rotor.
In still other embodiments of the invention the contact surface between the refiner plate segments and the rotor face are conical or contain compound curves.
Another embodiment of the invention relates to a segment of an annular retaining device forming part of a refiner rotor, said segment having a front working face, a rear face, exterior and interior circumferential ends and sides connecting said circumferential ends;
characterized by a thickness between the front working surface and the rear surface which is greater at the center of gravity of the segment than it is at the exterior circumferential end.
,. 'I ' . ~,, ~ ' ' 2~9~272 Still another aspect of the invention relates to a rotor for a fibre processing device having a rotor face, adapted to receive rotor plate segments, characterized in that the surface of the rotor face has an included angle such that the centrifugal forces acting on the ro~or plate segments when mounted on the rotor face will force the rotor plate segments against the rotor face surface.
N THE DRAWINGS
Figure 1 is a frontal view of the working surface of a refiner rotor.
Figure 2 is a section through one refiner segment corresponding to section D-D in figure 1.
Figures 3, 4 and 5 are enlargements of the rotor rim detail showing three possible configurations.
Referring to figure 1, a plurality of refiner segments 1 is mounted on a refiner rotor 2. One or more fasteners 3 such as bolts, clamps or clips are used to maintain each segment in contact with the rotor. Each plate segment has a surface comprised of bars 4 and grooves 5 which are illustrated on only one segment in figure 1.
Referring to figure 2 the item numbers are consistent with those in figure 1. The rotor 2 has a circumferential rim 6 against which the refiner segments 1 are located. The fasteners 3 maintain the segments 1 in contact with the rotor face 7. The angle shown as defines the angle of the surface of contact between the . .~ , .
" ~ , ,, - ~ .
209~272 refiner rotor face 7 and the plate segments 1. The axis of rotation is labelled A-A. The centre of gravity of a single plate segment is labelled CG. Centrifugal acceleration due to rotation creates a resultant radial force F acting through the centre of gravity CG. Figure 3 shows one possible configuration of the rotor rim interface in which the contact surfaces of both the segments and the rotor have a conical shape. Figure 4 shows another possible configuration of the rotor rim interface where the rotor contact surface is conical and the segment contact surface has a compound curvature.
Figure 5 shows still another possible configuration where the contact surfaces of both the segments and the rotor have a compound curvature. In figures 3, ~ and 5, the contact occurs at "C" and the contact angle ~ is the angle between a plane perpendicular to the axis of rotation and the surface tangent to the contacting :~
surfaces through "C".
The contact angle ~ is less than 85 and it is such that the resultant force due to the combination of centrifugal loading and contact friction will tend to force the plate segments 1 against the rotor face 7. The angle of the contact surface ~ is less than 178 and is such that the line of action of the centrifugal force F lies inboard of the line of action of the contact force between the segment 1 and the rim 6. In figure 2 in~oard means towards the right hand side of the drawing. In .
. .
2~96272 this way, there is no load applied to fasteners 3 due to centrifugal forces. All centrifugal forces tend to maintain the segments 1 in contact with the rotor rim 6 and the rotor face 7. Furthermore centrifugal force produces essentially no tensile stress in the plate segment. There are no fasteners located in the refining zone. The refiner plate segments can be much lighter than ~onventional refiner segments.
While the description herein refers to refining of fibrous materials, it will be recognized by those skilled in the art that the same invention can be applied to plate segments used for other fibre processing devices such as dispergers, mixers, fluffers and the like.
It is also evident that plate segments of a design similar to the present invention can also be used on a non-rotating mounting surface.
.
- , ;
. ~.
,
The present invention relates to refiners used to grind fibrous materials such as wood pulps. The working surfaces of refiners are typically comprised of bars and grooves of different configurations which vary depending on the type of material to be processed. The working surfaces are subject to wear and therefore they are designed to be replaceable. Typically, the surfaces in a mechanical pulping re~iner for wood chips require replacement about four times per year.
It has been conventional practice to manufacture the replaceable working surfaces in segments of an annulus which are then mounted in the refiner with mechanical means. The most common method of mounting is to place each segment against a rim near the outside diameter in order to locate the segment radially and then to attach the segment in place using one or more fasteners such as bolts.
At least one of the working surfaces is in rotation, and the rotating refiner plate segments are subjected to centrifugal forces. In large refiners, these forces can exceed fifty tons per segment. These forces may cause large stresses in the segments and in the rotor to which they are attached. Decreasing the weight of the segments reduces these forces however, with conventional bolting methods, the thickness of the plate segments is often a function cf the physical dimension of the bolts used. In addition, a conventional plate . .
20~272 segment must have a section modulus and moment of inertia sufficient to resist a large bending moment. This bending moment is caused because the line of action of the centrifugal force acting on the segment is not in line with the restraining force of the rotor rim. For conventional plates it is difficult to increase the width of the rotor rim in order that these force lines coincide without inducing very high bending stresses in the rotor itself.
The thickness and weight of conventional plates can be considered close to the optimum as a result of years of experience and development by many different manufacturers. Conventional plates are usually stressed in both compression and tension due to the bending moment described above. The materials used for these plate segments are typically very hard and brittle and in most cases it is preferable to reduce or avoid tensile stresses in these materials. Conventional plate designs preclude the use of many new ceramic materials due to these tensile stresses. Another disadvantage of some conventional plate segment mounting methods is that the bolting may affect the refining action in the fine bar section at the outer portion of the refining zone. A
further consideration in the method of plate segment mounting is the ease of replacement. Conventional plates are heavy to manipulate, require many bolts and worn plates may be difficult to remove due to damage of the 209~27~
bolt heads. A still further consideration is safety.
Conventional plates rely on bolts to restrain them. Bolt failures due to breakage or loosening can result in plate segments flying off the rotor. In addition, great care must be taken in manufacturing to avoid material defects which could cause the refiner plate segments to crack under the influence of tensile stresses.
The present invention has been developed to overcome the limitations of conventional refiner plate segments. A first object of the invention is to reduce the weight of the refiner plate segments. A second object of the invention is to minimize tensile stresses in the plate segments. A third object of the invention is to facilitate the changing of plate segments. A
fourth object of the invention is to provide a "fail-safe" retention of the segments on the rotor. A fifth object of the invention is to avoid process disturbances in the refining zone. A sixth object of the invention is to reduce the stress in the vicinity of the rim of the refiner rotor.
One embodiment of the invention relates to an apparatus for processing fibrous materials having at least one rotor with a rotor face and rotor plate segments adapted to be mounted on said rotor face, said rotor adapted to turn at a differential speed relative to adjacent plate segments, the invention comprising an included angle at the surface of contact between the - ~ . . , - ,. ~
: ' :
, : , .
' , : ' ' ' rotor plate segments and the rotor face such that centrifugal forces acting on the rotor plate segments will tend to force each plate segment against the face of the rotor.
In another aspect the invention relates to an apparatus for processing fibrous materials having at least one rotor with a rotor face and rotor plate segments adapted to be mounted on said rotor face, in which the plate segments are restrained by means of a rim on the rotor; the rim being characterized by a contact angle with the refiner plate segments of less than 85 such that resultant force at the rim due to the combination of centrifugal loading and contact friction will tend to force the plate segments against the face of the rotor.
In still other embodiments of the invention the contact surface between the refiner plate segments and the rotor face are conical or contain compound curves.
Another embodiment of the invention relates to a segment of an annular retaining device forming part of a refiner rotor, said segment having a front working face, a rear face, exterior and interior circumferential ends and sides connecting said circumferential ends;
characterized by a thickness between the front working surface and the rear surface which is greater at the center of gravity of the segment than it is at the exterior circumferential end.
,. 'I ' . ~,, ~ ' ' 2~9~272 Still another aspect of the invention relates to a rotor for a fibre processing device having a rotor face, adapted to receive rotor plate segments, characterized in that the surface of the rotor face has an included angle such that the centrifugal forces acting on the ro~or plate segments when mounted on the rotor face will force the rotor plate segments against the rotor face surface.
N THE DRAWINGS
Figure 1 is a frontal view of the working surface of a refiner rotor.
Figure 2 is a section through one refiner segment corresponding to section D-D in figure 1.
Figures 3, 4 and 5 are enlargements of the rotor rim detail showing three possible configurations.
Referring to figure 1, a plurality of refiner segments 1 is mounted on a refiner rotor 2. One or more fasteners 3 such as bolts, clamps or clips are used to maintain each segment in contact with the rotor. Each plate segment has a surface comprised of bars 4 and grooves 5 which are illustrated on only one segment in figure 1.
Referring to figure 2 the item numbers are consistent with those in figure 1. The rotor 2 has a circumferential rim 6 against which the refiner segments 1 are located. The fasteners 3 maintain the segments 1 in contact with the rotor face 7. The angle shown as defines the angle of the surface of contact between the . .~ , .
" ~ , ,, - ~ .
209~272 refiner rotor face 7 and the plate segments 1. The axis of rotation is labelled A-A. The centre of gravity of a single plate segment is labelled CG. Centrifugal acceleration due to rotation creates a resultant radial force F acting through the centre of gravity CG. Figure 3 shows one possible configuration of the rotor rim interface in which the contact surfaces of both the segments and the rotor have a conical shape. Figure 4 shows another possible configuration of the rotor rim interface where the rotor contact surface is conical and the segment contact surface has a compound curvature.
Figure 5 shows still another possible configuration where the contact surfaces of both the segments and the rotor have a compound curvature. In figures 3, ~ and 5, the contact occurs at "C" and the contact angle ~ is the angle between a plane perpendicular to the axis of rotation and the surface tangent to the contacting :~
surfaces through "C".
The contact angle ~ is less than 85 and it is such that the resultant force due to the combination of centrifugal loading and contact friction will tend to force the plate segments 1 against the rotor face 7. The angle of the contact surface ~ is less than 178 and is such that the line of action of the centrifugal force F lies inboard of the line of action of the contact force between the segment 1 and the rim 6. In figure 2 in~oard means towards the right hand side of the drawing. In .
. .
2~96272 this way, there is no load applied to fasteners 3 due to centrifugal forces. All centrifugal forces tend to maintain the segments 1 in contact with the rotor rim 6 and the rotor face 7. Furthermore centrifugal force produces essentially no tensile stress in the plate segment. There are no fasteners located in the refining zone. The refiner plate segments can be much lighter than ~onventional refiner segments.
While the description herein refers to refining of fibrous materials, it will be recognized by those skilled in the art that the same invention can be applied to plate segments used for other fibre processing devices such as dispergers, mixers, fluffers and the like.
It is also evident that plate segments of a design similar to the present invention can also be used on a non-rotating mounting surface.
.
- , ;
. ~.
,
Claims (8)
1. An apparatus for processing fibrous materials having at least one rotor with a rotor face and rotor plate segments adapted to be mounted on said rotor face, said rotor adapted to turn at a differential speed relative to adjacent plate segments; the invention comprising an included angle at the surface of contact between the rotor plate segments and the rotor face such that centrifugal forces acting on the rotor plate segments will tend to force each plate segment against the face of the rotor.
2. The apparatus of claim 1 in which the rotor face has an included angle of less than 178°.
3. The apparatus of claim 1 in which the plate segments are restrained by means of a rim on the rotor; the rim being characterized by a contact angle with the refiner plate segments of less than 85° such that resultant force at the rim due to the combination of centrifugal loading and contact friction will tend to force the plate segments against the face of the rotor.
4. The apparatus of claim 1 in which the contact surface between the refiner plate segments and the rotor face is conical.
5. The apparatus of claims 1 and 2 in which one or more of the contact surfaces between the refiner plate segments and the rotor face have compound curvature.
6. A segment of an annular refining device forming part of a refiner rotor, said segment having a front working face, a rear face, exterior and interior circumferential ends and sides connecting said circumferential ends;
characterized by a thickness between the front working surface and the rear surface which is greater at the center of gravity of the segment than it is at the exterior circumferential end.
characterized by a thickness between the front working surface and the rear surface which is greater at the center of gravity of the segment than it is at the exterior circumferential end.
7. A rotor for a fibre processing device having a rotor face, adapted to receive rotor plate segments, characterized in that the surface of the rotor face has an included angle such that the centrifugal forces acting on the rotor plate segments when mounted on the rotor face will force the rotor plate segments against the rotor surface.
8. The rotor for a fibre processing device of claim 8 having an included angle of less than 178° suitable for mounting a refiner plate or refiner plate segments.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2096272 CA2096272A1 (en) | 1993-05-14 | 1993-05-14 | Refiner plate segments |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2096272 CA2096272A1 (en) | 1993-05-14 | 1993-05-14 | Refiner plate segments |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2096272A1 true CA2096272A1 (en) | 1994-11-15 |
Family
ID=4151653
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2096272 Abandoned CA2096272A1 (en) | 1993-05-14 | 1993-05-14 | Refiner plate segments |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2096272A1 (en) |
-
1993
- 1993-05-14 CA CA 2096272 patent/CA2096272A1/en not_active Abandoned
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |