US4356085A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Rotary screening machine for pulp suspensions
Assignee: JM Voith GmbH
•
Filing: 1981-02-20
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Granted: 1982-10-26
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Expires: 2001-02-20
Abstract
Abstract The disclosure concerns a rotary screening machine for moving pulp suspension through a screening slot and for separating impurities from the pulp suspension. An annular rotatable drum is surrounded by an annular porous screen basket that is spaced away to define a screening slot. Pulp suspension is delivered to one axial end of the slot and is discharged from the other axial end of the slot. Generally wedged shaped vanes, widening in the axial direction between the leading and trailing ends of the vane, are provided around the drum. The wedge defining surfaces may also be inclined with respect to a respective plane perpendicular to the axis. The space between the wedge surfaces is an open volume. A wall in that space is oriented to help create appropriate vacuum and eddy conditions behind the vane. The drum may have different zones, with the lower zone being provided with vanes and the upper zone being generally smooth. Other types of vanes or projections may be provided in the intermediate zone. Water sprayed into the slot dilutes the suspension. The configuration of the vane causes conveyance of the pulp suspension generally toward the impurities outlet and conveys the impurities to that outlet. The configuration of the vanes also causes the suspension to pulsate across the screen basket which dislodges pulp suspension fibers that otherwise might become matted on the screen.
Inventors
- 👤 Werner Schon
- 👤 Albrecht Meinecke
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 19:45
CPC Classifications
B; B07; B07B; B07B1/00; B07B1/18; B07B1/20; D; D21; D21D; D21D5/00; D21D5/02; D21D5/023; D21D5/026
Claims Analysis
Total Claims: 63
Claim 1
Independent Claim
109 words
A rotary screening machine for removing impurities from a pulp suspension of fibers, comprising: an annular drum rotatable about an axis and having a annular periphery; a screen basket annularly around the periphery of the drum and radially spaced therefrom for defining an annular screening slot between the drum and the screen basket; a plurality of vanes supported on the annular periphery of the annular drum; each vane having a leading end and a trailing end with respect to the direction of rotation of the drum around the axis; each vane tapering gradually wider, measured along the axis of the drum, from the leading to the trailing end thereof.
Claim 2
Dependent Claim
109 words
A rotary screening machine for removing impurities from a pulp suspension of fibers, comprising: an annular drum rotatable about an axis and having a annular periphery; a screen basket annularly around the periphery of the drum and radially spaced therefrom for defining an annular screening slot between the drum and the screen basket; a plurality of vanes supported on the annular periphery of the annular drum; each vane having a leading end and a trailing end with respect to the direction of rotation of the drum around the axis; each vane tapering gradually wider, measured along the axis of the drum, from the leading to the trailing end thereof.
Claim 3
Dependent Claim
11 words
The machine of claim 1, wherein the axis is substantially vertical.
Claim 4
Dependent Claim
26 words
The machine of claim 2, wherein the screening slot includes an inlet for fiber suspension and an outlet for impurities that are separated from the suspension.
Claim 5
Dependent Claim
19 words
The machine of claim 3, wherein the impurities outlet is oriented for discharging impurities tangentially from the screening slot.
Claim 6
Dependent Claim
25 words
The machine of claim 1, wherein the vanes are arranged annularly around the drum, and adjacent vanes are staggered in their locations along the drum.
Claim 7
Dependent Claim
23 words
The machine of claim 1, wherein the drum and the screen basket are coaxial, and the screening slot has a constant radial width.
Claim 8
Dependent Claim
35 words
The machine of claim 1, wherein at an axial location along the length of the drum, the drum having spray holes therethrough for passage of diluting liquid into the screening slot from inside the drum.
Claim 9
Dependent Claim
113 words
The machine of claim 1, wherein the drum axis is oriented generally vertically and the drum is divided into at least two zones, including a lower zone, at which the drum is provided with the vanes, and an upper zone, which is free of the vanes; at the upper zone, the drum carries ribs arranged generally in a helical array around the drum, and the ribs cooperate in raising impurities along the axial length of the screening slot; the inlet for suspension to the screening slot being generally from the bottom of the screening slot and the outlet of impurities from the screening slot being generally toward the top of the screening slot.
Claim 10
Dependent Claim
32 words
The machine of claim 1, wherein each vane is wedge shaped and includes an upper wedge surface and a lower wedge surface by which the wedge shape of the vane is defined.
Claim 11
Dependent Claim
31 words
The machine of claim 9, wherein each wedge surface has a radially outer edge oriented so that a constant radius slot is defined between the wedge surfaces and the screen basket.
Claim 12
Dependent Claim
39 words
The machine of claim 9 wherein the upper surface and the lower surface of each vane meet to form a leading edge at the leading end of the vane, and the leading edge extending, generally radially from the drum.
Claim 13
Dependent Claim
54 words
The machine of claim 9, wherein the annular periphery of the drum is divided into at least two zones, one zone carrying the vanes and the other zone being free of vanes and thereby having a smoother surface; the smoother surface zone being axially nearer to the exit of impurities from the screening slot.
Claim 14
Dependent Claim
45 words
The machine of claim 12, further comprising means for feeding suspension into the screening slot; wherein the impurities exit from the screening slot generally toward one axial end of the screening slot; the impurities outlet being oriented for discharging impurities tangentially from the screen slot.
Claim 15
Dependent Claim
14 words
The machine of claim 13, wherein the impurities outlet lies above the screening slot.
Claim 16
Dependent Claim
35 words
The machine of claim 9, wherein at an axial location along the length of the drum, the drum having spray holes therethrough for passage of diluting liquid into the screening slot from inside the drum.
Claim 17
Dependent Claim
30 words
The machine of claim 15, wherein the screen basket includes fiber sorting openings therethrough, but the openings are not provided at the axial location generally opposed to the spray holes.
Claim 18
Dependent Claim
113 words
The machine of claim 9, wherein the drum axis is oriented generally vertically and the drum is divided into at least two zones, including a lower zone, at which the drum is provided with the vanes, and an upper zone, which is free of the vanes; at the upper zone, the drum carries ribs arranged generally in a helical array around the drum, and the ribs cooperate in raising impurities along the axial length of the screening slot; an inlet for suspension to the screening slot being generally from the bottom of the screening slot and an outlet of impurities from the screening slot being generally toward the top of the screening slot.
Claim 19
Dependent Claim
30 words
The machine of claim 17, wherein the drum includes a third zone above the upper zone, and in the third zone, the annular periphery of the drum being essentially smooth.
Claim 20
Dependent Claim
26 words
The machine of claim 9, wherein the screening slot includes an inlet for fiber suspension and an outlet for impurities that are separated from the suspension.
Claim 21
Dependent Claim
19 words
The machine of claim 19, wherein the impurities outlet is oriented for discharging impurities tangentially from the screening slot.
Claim 22
Dependent Claim
14 words
The machine of claim 20, wherein the impurities outlet lies above the screening slot.
Claim 23
Dependent Claim
25 words
The machine of claim 9, wherein each vane is shaped so that a space is defined between the upper and the lower wedge surfaces thereof.
Claim 24
Dependent Claim
67 words
The machine of claim 22, further comprising a wall located in the space, facing radially outwardly toward the screen basket, extending generally rearwardly from the leading end of the vane, extending between the upper and lower wedge surfaces of the vane and being oriented with respect to the screen basket for providing an additional pressure pulse on the suspension in the screening slot as the vanes rotate.
Claim 25
Dependent Claim
67 words
The machine of claim 23, wherein the wall is so shaped that, as the wedge surfaces taper wider toward the vane rear end, which enlarges the space, the wall is also so oriented that the volume of the space, as defined between the upper and lower wedge surfaces and the wall and the screen basket, increases from the leading end to the trailing end of the vane.
Claim 26
Dependent Claim
19 words
The machine of claim 24, wherein the orientation of the wall deviates from the circumferential direction around the drum.
Claim 27
Dependent Claim
45 words
The machine of claim 25, wherein the wall is so oriented that the radial width between the wall and the screen basket and the axial height between the wedge surfaces of the space, both increase from the leading to the trailing end of the vane.
Claim 28
Dependent Claim
31 words
The machine of claim 26, wherein each wedge surface has a radially outer edge oriented so that a constant radius slot is defined between the wedge surfaces and the screen basket.
Claim 29
Dependent Claim
43 words
The machine of claim 23, wherein the wall is so oriented that it is radially further from the screen basket at the leading end of the vane and is relatively radially closer to the screen basket toward the trailing end of the vane.
Claim 30
Dependent Claim
27 words
The machine of claim 28, further comprising means pressurizing the screening machine for increasing the pressure in the screening slot above the pressure outside the screen basket.
Claim 31
Dependent Claim
113 words
The machine of claim 22, wherein the drum axis is oriented generally vertically and the drum is divided into at least two zones, including a lower zone, at which the drum is provided with the vanes, and an upper zone, which is free of the vanes; at the upper zone, the drum carries ribs arranged generally in a helical array around the drum, and the ribs cooperate in raising impurities along the axial length of the screening slot; the inlet for suspension to the screening slot being generally from the bottom of the screening slot and the outlet of impurities from the screening slot being generally toward the top of the screening slot.
Claim 32
Dependent Claim
30 words
The machine of claim 30, wherein the drum includes a third zone above the upper zone, and in the third zone, the annular periphery of the drum being essentially smooth.
Claim 33
Dependent Claim
17 words
The machine of claims 1 or 22, wherein the radial dimension of the vanes is substantially constant.
Claim 34
Dependent Claim
21 words
The machine of claims 1 or 22, wherein the radial dimension of the vanes is greatest at the leading end thereof.
Claim 35
Dependent Claim
22 words
The machine of claim 1 or claim 22 wherein the vanes are supported directly on the annular periphery of the annular drum.
Claim 36
Dependent Claim
59 words
The machine of claim 22, wherein each vane comprises two walls, the walls extending generally radially from the drum, the space being defined between the walls, the upper surface and said lower surface each being defined by one of the walls, the walls meeting to define the leading edge, and the leading edge extending generally radially from said drum.
Claim 37
Dependent Claim
50 words
The machine of claim 9, wherein at least one of the upper and lower wedge surfaces is inclined from a plane that is perpendicular to the axis, when that wedge surface is viewed along a radius of the drum, for producing a fiber suspension conveyence component through the screening slot.
Claim 38
Dependent Claim
43 words
The machine of claim 36, wherein at least one wedge surface of the vane is inclined from a plane that is perpendicular to the axis for providing a component of movement of the fiber suspension that is radially outward toward the screen basket.
Claim 39
Dependent Claim
40 words
The machine of claim 37, wherein the screening slot is unpressurized; means for feeding fiber suspension into the screening slot; the feeding means feeding suspension from outside the screen basket to pass into the screeing slot through the screen basket.
Claim 40
Dependent Claim
114 words
The machine of claim 36, further comprising means for feeding suspension into the screening slot; an impurities exit from the screening slot generally toward one axial end of the screening slot; a second plurality of vanes nearer to the impurities outlet generally than the first mentioned plurality of vanes; the wedge surface that faces away from the impurities outlet of each of the second plurality of vanes being inclined with respect to a plane that is perpendicular to the axis, so as to create a smaller component of conveyance of suspension through the screen slot away from the impurities outlet than the corresponding wedge surface of each of the first mentioned plurality of vanes.
Claim 41
Dependent Claim
29 words
The machine of claim 39, wherein the screening slot is unpressurized, and the impurities outlet is nearer the top of the screening slot with the axis being substantially vertical.
Claim 42
Dependent Claim
54 words
The machine of claim 40, wherein the annular periphery of the drum is divided into at least two zones, one zone carrying the vanes and the other zone being free of vanes and thereby having a smoother surface; the smoother surface zone being axially nearer to the exit of impurities from the screening slot.
Claim 43
Dependent Claim
19 words
The machine of claim 39, wherein the impurities outlet is oriented for discharging impurities tangentially from the screen slot.
Claim 44
Dependent Claim
109 words
The machine of claim 36, further comprising means for feeding suspension into the screening slot; wherein the impurities exit from the screening slot generally toward one axial end of the screening slot; a second plurality of vanes nearer to the impurities outlet generally than the first mentioned plurality of vanes; the wedge surface facing away from the impurities outlet of each of the second plurality of vanes being of shorter radial length toward the screen basket than the other wedge surface of that vane, leaving a larger radial space between the shorter radial length wedge surface and the screen basket than for the other wedge surface of that vane.
Claim 45
Dependent Claim
44 words
The machine of claim 12 or 43, wherein a group of the vanes in the zone of the drum carrying vanes are the vanes adjacent the smoother surface zone, and are arrayed approximately once around the circumference of the drum generally in a helix.
Claim 46
Dependent Claim
29 words
The machine of claim 44, wherein the screening slot is unpressurized, and the impurities outlet is nearer the top of the screening slot with the axis being substantially vertical.
Claim 47
Dependent Claim
29 words
The machine of claim 43, wherein the screening slot is unpressurized, and the impurities outlet is nearer the top of the screening slot with the axis being substantially vertical.
Claim 48
Dependent Claim
24 words
The machine of claim 36, wherein each vane is shaped so that a space is defined between the upper and lower wedge surfaces thereof.
Claim 49
Dependent Claim
18 words
The machine of claim 41 wherein the space is open in the outwardly radial direction from the drum.
Claim 50
Dependent Claim
67 words
The machine of claim 47, further comprising a wall located in the space, facing radially outwardly toward the screen baskets extending generally rearwardly from the leading end of the vane, extending between the upper and lower wedge surfaces of the vane and being oriented with respect to the screen basket for providing an additional pressure pulse on the suspension in the screening slot as the vanes rotate.
Claim 51
Dependent Claim
80 words
The machine of claim 49, wherein the screening slot has an outlet for impurities that are separated out of the fiber suspension during rotation of the vanes through the screening slot; means for feeding fiber suspension into the screening slot; the wedge surfaces being so inclined with respect to a plane perpendicular to the axis as to produce components of conveyance for the fiber suspension in a direction along the axis and toward the impurities outlet from the screening slot.
Claim 52
Dependent Claim
33 words
The machine of claim 50, wherein the wedge surfaces are also so inclined that they also produce components of conveyance of the fiber suspension in the opposite direction away from the impurities outlet.
Claim 53
Dependent Claim
43 words
The machine of claim 47, wherein at least one wedge surface of the vane is inclined from a plane that is perpendicular to the axis for providing a component of movement of the fiber suspension that is radially outward toward the screen basket.
Claim 54
Dependent Claim
40 words
The machine of claim 52, wherein the screening slot is unpressurized; means for feeding fiber suspension into the screening slot; the feeding means feeding suspension from outside the screen basket to pass into the screening slot through the screen basket.
Claim 55
Dependent Claim
80 words
The machine of claim 36, wherein the screening slot has an outlet for impurities that are separated out of the fiber suspension during rotation of the vanes through the screening slot; means for feeding fiber suspension into the screening slot; the wedge surfaces being so inclined with respect to a plane perpendicular to the axis as to produce components of conveyance for the fiber suspension in a direction along the axis and toward the impurities outlet from the screening slot.
Claim 56
Dependent Claim
43 words
The machine of claim 54, wherein at least one wedge surface of the vane is inclined from a plane that is perpendicular to the axis for providing a component of movement of the fiber suspension that is radially outward toward the screen basket.
Claim 57
Dependent Claim
40 words
The machine of claim 55, wherein the screening slot is unpressurized; means for feeding fiber suspension into the screening slot; the feeding means feeding suspension from outside the screen basket to pass into the screening slot through the screen basket.
Claim 58
Dependent Claim
106 words
The machine of claim 54, wherein the impurities exit from the screening slot in generally toward one axial end of the screening slot; a second plurality of vanes nearer to the impurities outlet generally than the first mentioned plurality of vanes; the wedge surface that faces away from the impurities outlet of each of the second plurality of vanes being inclined with respect to a plane that is perpendicular to the axis so as to create a smaller component of conveyance of suspension through the screen slot away from the impurities outlet than the corresponding wedge surface of each of the first mentioned plurality of vanes.
Claim 59
Dependent Claim
19 words
The machine of claim 54, wherein the impurities outlet is oriented for discharging impurities tangentially from the screen slot.
Claim 60
Dependent Claim
15 words
The machine of claim 58, wherein the impurities outlet lies generally above the screening slot.
Claim 61
Dependent Claim
20 words
The machine of claim 54, wherein the screening slot is unpressurized as compared with the pressure outside the screen basket.
Claim 62
Dependent Claim
33 words
The machine of claim 60, wherein the wedge surfaces are also so inclined that they also produce components of conveyance of the fiber suspension in the opposite direction away from the impurities outlet.
Claim 63
Dependent Claim
42 words
The machine of claim 61, wherein the inclined wedge surface of the vane is inclined from a plane that is perpendicular to the axis for providing a component of movement of the fiber suspension that is radially outward toward the screen basket.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-10-25 | 1986-04-26 | 1986-10-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-10-25 | 1990-04-26 | 1990-10-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-10-25 | 1994-04-26 | 1994-10-26 | $7700.00 | Window Closed / Lapsed |