CA2034074A1 - Air doctor - Google Patents
Air doctorInfo
- Publication number
- CA2034074A1 CA2034074A1 CA 2034074 CA2034074A CA2034074A1 CA 2034074 A1 CA2034074 A1 CA 2034074A1 CA 2034074 CA2034074 CA 2034074 CA 2034074 A CA2034074 A CA 2034074A CA 2034074 A1 CA2034074 A1 CA 2034074A1
- Authority
- CA
- Canada
- Prior art keywords
- air
- nozzle
- doctor
- cut
- web
- 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
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H25/00—After-treatment of paper not provided for in groups D21H17/00 - D21H23/00
- D21H25/08—Rearranging applied substances, e.g. metering, smoothing; Removing excess material
- D21H25/16—Rearranging applied substances, e.g. metering, smoothing; Removing excess material with a blast of vapour or gas, e.g. air knife
Landscapes
- Paper (AREA)
- Cleaning In General (AREA)
- Coating Apparatus (AREA)
Abstract
(57) ABSTRACT OF THE DISCLOSURE
This publication discloses a rotatable air doctor. According to the invention a body (1) encloses an air channel (2) of the air doctor, said air channel (2) exiting via nozzle air ducts (4) to nozzles (3). The nozzle air ducts (4) are provided with cut-off means (5, 7) with which the air flow from the air channel (2) via the nozzle air ducts (4) to the nozzles (3) can be shut off. During the use of the air doctor, the air flow to the nozzle (3) being used for doctoring is shut off with the help of the cut-off means (5, 7) and the air doctor is rotated by 180° about its longitudinal axis, whereby a clean nozzle (3) can be oriented toward the web. The cut-off in the nozzle air duct (4) of this nozzle (3) is released, whereby the nozzle (3) of the blocked duct (4) can be cleaned.
(Figure 1)
This publication discloses a rotatable air doctor. According to the invention a body (1) encloses an air channel (2) of the air doctor, said air channel (2) exiting via nozzle air ducts (4) to nozzles (3). The nozzle air ducts (4) are provided with cut-off means (5, 7) with which the air flow from the air channel (2) via the nozzle air ducts (4) to the nozzles (3) can be shut off. During the use of the air doctor, the air flow to the nozzle (3) being used for doctoring is shut off with the help of the cut-off means (5, 7) and the air doctor is rotated by 180° about its longitudinal axis, whereby a clean nozzle (3) can be oriented toward the web. The cut-off in the nozzle air duct (4) of this nozzle (3) is released, whereby the nozzle (3) of the blocked duct (4) can be cleaned.
(Figure 1)
Description
2~3~74 ~ ~
Air doctor The present invention relateQ to an ai:r doctor in accordance with the preamble of claim 1.
Air doctors are used for doctoring away exce~s coating mix from the web surface in the co~ting process of paper web~.
During coating~ the mix is generally applied onto the web with an excess of approx. 20...50 %, and after application, the excess is removed by means of an air doctor. Extending over the entire length of the web, the air doctor has an air channel which exits into a narrow, slitted nozzle directed toward the web. When the channel of the air doctor is pressurized with a compressor, a narrow air knife jet is ~-discharged from the nozzle toward the web. The air lcnife is generally oriented contradirectionally to the machine direction o the web. Air doctors can as well be used for issuing against the web other types of gases than air such as different kinds of vapours. These substances can be availed to control the propertie~ of the coated web ., :
including, e.g., its moisture.
The nozzle of the air doctor must be relatively narrow, since the air knife jet exiting from the nozzle has to be thin and sharply delineated. Because the air doctor is ;
placed close to the web, the air jet discharging from the nozzle splashes the coating mix also on the nozzle, thereby soiling it. With the contamination o~ the nozzle, the air knife jet becomes weaker and less defined, whereby the air knife cannot anymore accurately doctor away the surplus coating mix from the web surface. Thence, at the soiling of the nozzle, the coater must be run down and the nozzle cleaned, which results in production halts.
.
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2 2~3~07~
In order to make it pos~ible to en~ure a continuous operation at the coater, rotatable air doctors with two nozzles have been developed. In such an air doctor the nozzles are placed to the opposite sides of the longitudinal axis of the air doctor, and at the soiling of the nozzle, the air f,eed is cut off and the air doctor iY rotated by 180 so as to aim a clean nozzle toward the web. The contaminated nozzle can now be cleaned, and after cleaning, be correspondingly rotated toward the web when the other nozzle in its turn becomes soiled.
A prior art construction has two air channels extending over the entire width of the web, each channel exiting via a separate nozzle. The air channelq have cut-off means, with which the air feed to the nozzle in the cleaning position is shut off, while the air feed channel to the other nozzle, which is in the air knife position, is opened. This air doctor construction has additionally narrow air feed ducts, through which air i9 blasted onto the nozzle being in the cleaning position. These small ducts are connected to a sep-arate auxiliary compressor. The purpose of these ducts is to prevent the nozzle being in the cleaning position from becoming clogged by any possible mix residues in the nozzle.
The above-described air doctor with its plurality of air ducts and compressors is a complicated and expensive design.
The air flowing in the air channel is heated at the restrictions of the channel, since a channel of relatively small cross section must be used. Because the air is fed to the nozzle being used via a dedicated channel of the nozzle, the air doctor becomes heated from side of the air channel being used, and the heating results in an asymmetric tension in the air doctor body that distorts the body.
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. ~ . .: . : :.
. : . : :
2 ~ 3 ~
~nother construction of dual-channel air doctor is comprised of a round pipe forming the air duct, and of a body adapted about the pipe. The air channel has a 31it exte~ding over the entire width of the web and aiming toward the web.
Correspondingly, the body has two oppoaingly aligned openings both of which exit into their respective nozzles. `~
puring the operation of the air brush, the air flows via the ~ ;~
air channel and the openings of the body to the nozzle~ and therefrom Eurther toward the web. With the contamination of the nozzle, the body is rotated by 180 about the pipe forming the air channel, whereby the one of the openings of ~ ;
the body and the nozzle associated with it are rotated to coincide with the ~lit of the air channel. This construction ~`
is simple and practicable. Such an air doctor has, however, relatively high production costq because of the tight, yet rotatable joint that must be fabricated between the air channel pipe and the body. For air doctors used in paper machines of particularly large width, the fabrication o such a joint is complicated.
It is an object of the present invention to achieve such an air doctor of simple and reliable construction that provides for an easy control of the air knife jet.
j .
The invention is ba ed on designing the air doctor to have a body enclosing an air channel leading to nozzle ducts for i~quing air knife jets onto the web, said ductq being provided with cut-off means. Such cut-off meanq can be u~ed for shutting off air flow to the nozzle when the nozzle is in the cleaning position.
More specifically, the air brush in accordance with inven-tion is characterized by what is stated in the characteriz-ing part of claim 1.
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The invention provides 3ignificant benefits.
The air doctor in accordance with the present invention has a particularly simple construction. ThuiY, it can be produced at a low cost and provides an extremely reliable operation even in coaters of large web widths. The air flow rate through the nozzles is easy to control by choking as necessary according to run conditions and coating mix used. ~, A construction in accordance with one of the embodiments of the invention makes it also possible to achieve an air knife jet with a vortex, complemented with the poiYsibility of altering the direction of the vortex. By virtue of a single large-diameter air channel in the air doctor, an even heat distribution over the entire cross section of the air doctor is achieved. Air flows in this channel at a low rate, thereby avoiding the generation of heat streY~e3 from restriction of the air flow and isubsequent heating. Since the distortion of the air brush body by heat i3tresses is circumvented, the nozzle tip can be held at a constant distance from the web. Due to the single-channel construc-tion of the air doctor, only a single compresisor is needed.
The nozzle of the air doctor in accordance with the inven-tion can be provided with a baffle, whereby a vortex with a desired direction can be imposed on the air knife jet.
The invention iq next examined in detail with the help of the attached drawings.
.
Figure 1 shows a cross-sectional view of an air doctor construction in accordance with the present invention.
Figure 2 shows a partially cross-isectional view of another air doctor construction in accordance with the present invention.
- - : . , ~ :
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: .; : : . : : :
. : . :: .. : , , :: : , : . .
- : . : , . .
2~3~74 Figure 3 shows a partially cro~s-sectional view of a third air doctor construction in accordance with the present invention.
The preferred embodiment of the invention is illu~trated in Fig. 1. The air doctor shown in Fig. 1 comprises a body 1 forming a wide air channel 2. Exiting from the opposite sides of the air channel 2, there are nozzle ductq 4 routed to nozzles 3. Flexible pressure hoses 5 and 6 are fitted onto grooves fabricated on the nozzle ducts 4, said hoses having a ridged-tip profile 7 on their sides facing the nozzle duct 4.
The body 1 with its enclosed air channel 2, the nozzle ducts 4 and the nozzles 3 are extended over the entire width of the web. When the nozzle 3 being in the operating position becomes soiled, its associated nozzle d~lct 4 is Qhut o~f, and the air doctor is rotated about its longitudinal axis by 180, whereby the nozzle 3 on the opposite side is rotated to be oriented toward the web. Then, the nozzle duct 4 leading to the nozzle 3 is opened, allowing the air to discharge via the nozzle 3 onto the web.
In the air doctor illustrated in Fig. 1, the nozzle 3 being in the cleaning position is shut off by releasing compressed air into the pressure hose 6. The pressurized hose 6 then expands outwardly from its groove, and the tip part 7 of the hose 6 is pressed tightly against the opposite wall of the nozzle d~ct 4. During the time the nozzle duct 4 of the nozzle 3 being cleaned is shut off, air is discharged from - the air channel 2 onto the web to be coated via the nozzle 3 being used as indicated by the arrows in Fig. 1. The pressure hose 5 in the air duct 4 of the nozzle 3 being in the operating position is depressurized, whereby the hose 5 . - .. . . . .
::- .: :. . .
-: . ,, i:: .
: , :
6 2 ~ 3 ~ ~ 7~!
contracts to the bottom of the groove, thuq allowing an unobstructed air flow in the nozzle duct 4.
., One of the advantage~ of the thiq embodiment i9 that, when desired, a small air flow can be arranged to pas~ via the nozzle 3 being in the cleaning position as a controlled leakage from the air channel 2 by appropriately notching the tip part 7 of the pressure hoses 5 and 6.
In an advantageous e~bodiment of the invention illustrated in Fig. 2, the pressure hose with a ridged-tip profile is replaced by a conventional pressure hose 8 and a flap 9 adapted over the groove of the nozzle duct 4. The flap 9 is attached at its edge on the side of the air channel 2 to the edge of the groove, allowing its rotation about this attachment. In this embodiment the nozzle duct 4 is shut off by inflating the pressure hose 8 in the same manner as described above. The expansion of the hose rotates the other edge of the flap 9 against the opposite wall of the nozzle duct 4, whereby the flap 9 obstructs the nozzle duct 4. The other side of the air doctor, not shown, is the mirror image of the described diagram. The illustrated construction makes both walls of the nozzle duct 4 smooth when the duct 4 is controlled to open.
The advantageous embodiment illustrated in Fig. 3 has a baffle 10 adapted to the middle of the nozzle ducts 4. Both sides of the duct 4 have grooves filled with the cut-off means 8, 9 shown in Fig. 2. The baffle 10 divides the nozzle duct 4 into two parts, making the independent cut-off of both parts possible. Closing one of the ducts generates a vortex into the air jet exiting the nozzle 3, and further, allows the selection of the rotational direction of the vortex according to which one of the ducts is cut off. When the nozzle 3 has been rotated to the cleaning position, the ~,.. - . . .. . . ..
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_ 7 2~3~7~
ducts on both sides of the baffle are shut off. ~ven in thiq construction, tha other side with its nozzles 3, ducts 4, baffles 10 and cut-off means 8, 9 is a mirror image of the construction shown in this diagram.
The disclosed invention is not limited to the alternative embodiments described above. Thus, the flap 9 used in the embodiments illustrated in Figs. 2 and 3 can be replaced by a flexible membrane. Further, the medium used in the pressure hose 5 can alternatively be either a gas or a liquid. A controlled air leakage to the no7zle 3 being in the cleaning position can also be achieved by a reduction of the pressure in the hose. This arrangement dispense~ with ~--the need for use of a notched hose 5, 6. Moreover, the shape of the air channel 2 need not necessarily be square, but in~tead, can be freely selected to have, e.g., a circular or ellipsoidal cross section. The shape of the nozzles 3 and nozzle ducts ~ must, of course, be determined with the design methods o flow dynamics separately for each case to obtain a desired form of the air knife jet. The slitted gap of the nozzle 3 can be either fixed, or alternatively, variable by conventional means such as open/close screws.
Finally, the cut-off means 5 can be located within the nozzle duct 4 in a manner different from that described for the exemplifying embodiments.
,~ . . . . .
. . . :
. . ~ . ..
, :. :
' ~ : ' , .. ,, . . , !
Air doctor The present invention relateQ to an ai:r doctor in accordance with the preamble of claim 1.
Air doctors are used for doctoring away exce~s coating mix from the web surface in the co~ting process of paper web~.
During coating~ the mix is generally applied onto the web with an excess of approx. 20...50 %, and after application, the excess is removed by means of an air doctor. Extending over the entire length of the web, the air doctor has an air channel which exits into a narrow, slitted nozzle directed toward the web. When the channel of the air doctor is pressurized with a compressor, a narrow air knife jet is ~-discharged from the nozzle toward the web. The air lcnife is generally oriented contradirectionally to the machine direction o the web. Air doctors can as well be used for issuing against the web other types of gases than air such as different kinds of vapours. These substances can be availed to control the propertie~ of the coated web ., :
including, e.g., its moisture.
The nozzle of the air doctor must be relatively narrow, since the air knife jet exiting from the nozzle has to be thin and sharply delineated. Because the air doctor is ;
placed close to the web, the air jet discharging from the nozzle splashes the coating mix also on the nozzle, thereby soiling it. With the contamination o~ the nozzle, the air knife jet becomes weaker and less defined, whereby the air knife cannot anymore accurately doctor away the surplus coating mix from the web surface. Thence, at the soiling of the nozzle, the coater must be run down and the nozzle cleaned, which results in production halts.
.
: ,.: ~ . -. : .. . - . . : . - : : .,.: .,. . :
:: . ~ , -.:. ., . . ~ : : , . .: . . : -; - .:~, ' , :: . , ., : . ~ .. ' : :, .:: . .. . . . . .. . . .
2 2~3~07~
In order to make it pos~ible to en~ure a continuous operation at the coater, rotatable air doctors with two nozzles have been developed. In such an air doctor the nozzles are placed to the opposite sides of the longitudinal axis of the air doctor, and at the soiling of the nozzle, the air f,eed is cut off and the air doctor iY rotated by 180 so as to aim a clean nozzle toward the web. The contaminated nozzle can now be cleaned, and after cleaning, be correspondingly rotated toward the web when the other nozzle in its turn becomes soiled.
A prior art construction has two air channels extending over the entire width of the web, each channel exiting via a separate nozzle. The air channelq have cut-off means, with which the air feed to the nozzle in the cleaning position is shut off, while the air feed channel to the other nozzle, which is in the air knife position, is opened. This air doctor construction has additionally narrow air feed ducts, through which air i9 blasted onto the nozzle being in the cleaning position. These small ducts are connected to a sep-arate auxiliary compressor. The purpose of these ducts is to prevent the nozzle being in the cleaning position from becoming clogged by any possible mix residues in the nozzle.
The above-described air doctor with its plurality of air ducts and compressors is a complicated and expensive design.
The air flowing in the air channel is heated at the restrictions of the channel, since a channel of relatively small cross section must be used. Because the air is fed to the nozzle being used via a dedicated channel of the nozzle, the air doctor becomes heated from side of the air channel being used, and the heating results in an asymmetric tension in the air doctor body that distorts the body.
. : : -, - - :
. . .. - . . :
: . , , ~: . . , .,. , . : : ..
. ~ . .: . : :.
. : . : :
2 ~ 3 ~
~nother construction of dual-channel air doctor is comprised of a round pipe forming the air duct, and of a body adapted about the pipe. The air channel has a 31it exte~ding over the entire width of the web and aiming toward the web.
Correspondingly, the body has two oppoaingly aligned openings both of which exit into their respective nozzles. `~
puring the operation of the air brush, the air flows via the ~ ;~
air channel and the openings of the body to the nozzle~ and therefrom Eurther toward the web. With the contamination of the nozzle, the body is rotated by 180 about the pipe forming the air channel, whereby the one of the openings of ~ ;
the body and the nozzle associated with it are rotated to coincide with the ~lit of the air channel. This construction ~`
is simple and practicable. Such an air doctor has, however, relatively high production costq because of the tight, yet rotatable joint that must be fabricated between the air channel pipe and the body. For air doctors used in paper machines of particularly large width, the fabrication o such a joint is complicated.
It is an object of the present invention to achieve such an air doctor of simple and reliable construction that provides for an easy control of the air knife jet.
j .
The invention is ba ed on designing the air doctor to have a body enclosing an air channel leading to nozzle ducts for i~quing air knife jets onto the web, said ductq being provided with cut-off means. Such cut-off meanq can be u~ed for shutting off air flow to the nozzle when the nozzle is in the cleaning position.
More specifically, the air brush in accordance with inven-tion is characterized by what is stated in the characteriz-ing part of claim 1.
. .: . ~ . . - . ~ :
; ~ . , ::. . .. ;,,,,;~, , . : . ~ :
~: :: . . . . . .
,: ~ . . ,. . ; , ~ ; : ~
g 2~3ll~7~
The invention provides 3ignificant benefits.
The air doctor in accordance with the present invention has a particularly simple construction. ThuiY, it can be produced at a low cost and provides an extremely reliable operation even in coaters of large web widths. The air flow rate through the nozzles is easy to control by choking as necessary according to run conditions and coating mix used. ~, A construction in accordance with one of the embodiments of the invention makes it also possible to achieve an air knife jet with a vortex, complemented with the poiYsibility of altering the direction of the vortex. By virtue of a single large-diameter air channel in the air doctor, an even heat distribution over the entire cross section of the air doctor is achieved. Air flows in this channel at a low rate, thereby avoiding the generation of heat streY~e3 from restriction of the air flow and isubsequent heating. Since the distortion of the air brush body by heat i3tresses is circumvented, the nozzle tip can be held at a constant distance from the web. Due to the single-channel construc-tion of the air doctor, only a single compresisor is needed.
The nozzle of the air doctor in accordance with the inven-tion can be provided with a baffle, whereby a vortex with a desired direction can be imposed on the air knife jet.
The invention iq next examined in detail with the help of the attached drawings.
.
Figure 1 shows a cross-sectional view of an air doctor construction in accordance with the present invention.
Figure 2 shows a partially cross-isectional view of another air doctor construction in accordance with the present invention.
- - : . , ~ :
:. . ::.: . -:: ~ . :. . - . ~ .. .
: .; : : . : : :
. : . :: .. : , , :: : , : . .
- : . : , . .
2~3~74 Figure 3 shows a partially cro~s-sectional view of a third air doctor construction in accordance with the present invention.
The preferred embodiment of the invention is illu~trated in Fig. 1. The air doctor shown in Fig. 1 comprises a body 1 forming a wide air channel 2. Exiting from the opposite sides of the air channel 2, there are nozzle ductq 4 routed to nozzles 3. Flexible pressure hoses 5 and 6 are fitted onto grooves fabricated on the nozzle ducts 4, said hoses having a ridged-tip profile 7 on their sides facing the nozzle duct 4.
The body 1 with its enclosed air channel 2, the nozzle ducts 4 and the nozzles 3 are extended over the entire width of the web. When the nozzle 3 being in the operating position becomes soiled, its associated nozzle d~lct 4 is Qhut o~f, and the air doctor is rotated about its longitudinal axis by 180, whereby the nozzle 3 on the opposite side is rotated to be oriented toward the web. Then, the nozzle duct 4 leading to the nozzle 3 is opened, allowing the air to discharge via the nozzle 3 onto the web.
In the air doctor illustrated in Fig. 1, the nozzle 3 being in the cleaning position is shut off by releasing compressed air into the pressure hose 6. The pressurized hose 6 then expands outwardly from its groove, and the tip part 7 of the hose 6 is pressed tightly against the opposite wall of the nozzle d~ct 4. During the time the nozzle duct 4 of the nozzle 3 being cleaned is shut off, air is discharged from - the air channel 2 onto the web to be coated via the nozzle 3 being used as indicated by the arrows in Fig. 1. The pressure hose 5 in the air duct 4 of the nozzle 3 being in the operating position is depressurized, whereby the hose 5 . - .. . . . .
::- .: :. . .
-: . ,, i:: .
: , :
6 2 ~ 3 ~ ~ 7~!
contracts to the bottom of the groove, thuq allowing an unobstructed air flow in the nozzle duct 4.
., One of the advantage~ of the thiq embodiment i9 that, when desired, a small air flow can be arranged to pas~ via the nozzle 3 being in the cleaning position as a controlled leakage from the air channel 2 by appropriately notching the tip part 7 of the pressure hoses 5 and 6.
In an advantageous e~bodiment of the invention illustrated in Fig. 2, the pressure hose with a ridged-tip profile is replaced by a conventional pressure hose 8 and a flap 9 adapted over the groove of the nozzle duct 4. The flap 9 is attached at its edge on the side of the air channel 2 to the edge of the groove, allowing its rotation about this attachment. In this embodiment the nozzle duct 4 is shut off by inflating the pressure hose 8 in the same manner as described above. The expansion of the hose rotates the other edge of the flap 9 against the opposite wall of the nozzle duct 4, whereby the flap 9 obstructs the nozzle duct 4. The other side of the air doctor, not shown, is the mirror image of the described diagram. The illustrated construction makes both walls of the nozzle duct 4 smooth when the duct 4 is controlled to open.
The advantageous embodiment illustrated in Fig. 3 has a baffle 10 adapted to the middle of the nozzle ducts 4. Both sides of the duct 4 have grooves filled with the cut-off means 8, 9 shown in Fig. 2. The baffle 10 divides the nozzle duct 4 into two parts, making the independent cut-off of both parts possible. Closing one of the ducts generates a vortex into the air jet exiting the nozzle 3, and further, allows the selection of the rotational direction of the vortex according to which one of the ducts is cut off. When the nozzle 3 has been rotated to the cleaning position, the ~,.. - . . .. . . ..
:.:. : : . ::. . ,: ,. .: , : : . . , ,, -, - : : . , , : . ~
. : : , -, - . ~, , ::
:. . . : : : : : .:
-: . .. . - . . . .. .
., :- ~ . , , : . . ~ , :
:,, ,..:,: ... : ~ :: ~: ., : : . , .
: .
_ 7 2~3~7~
ducts on both sides of the baffle are shut off. ~ven in thiq construction, tha other side with its nozzles 3, ducts 4, baffles 10 and cut-off means 8, 9 is a mirror image of the construction shown in this diagram.
The disclosed invention is not limited to the alternative embodiments described above. Thus, the flap 9 used in the embodiments illustrated in Figs. 2 and 3 can be replaced by a flexible membrane. Further, the medium used in the pressure hose 5 can alternatively be either a gas or a liquid. A controlled air leakage to the no7zle 3 being in the cleaning position can also be achieved by a reduction of the pressure in the hose. This arrangement dispense~ with ~--the need for use of a notched hose 5, 6. Moreover, the shape of the air channel 2 need not necessarily be square, but in~tead, can be freely selected to have, e.g., a circular or ellipsoidal cross section. The shape of the nozzles 3 and nozzle ducts ~ must, of course, be determined with the design methods o flow dynamics separately for each case to obtain a desired form of the air knife jet. The slitted gap of the nozzle 3 can be either fixed, or alternatively, variable by conventional means such as open/close screws.
Finally, the cut-off means 5 can be located within the nozzle duct 4 in a manner different from that described for the exemplifying embodiments.
,~ . . . . .
. . . :
. . ~ . ..
, :. :
' ~ : ' , .. ,, . . , !
Claims (6)
1. A rotatable air doctor for blowing gas or steam toward a web to be coated, particularly a paper web, said air doctor comprising - a body (1) extending over the entire width of the web to be coated and enclosing an air channel (2), - at least two nozzle air ducts (4) leading from the air channel (2) each to an individual nozzle (3 extending over the entire width of the web, c h a r a c t e r i z e d by - cut-off means (5, 7), adapted to each nozzle air duct (4) and extending over the entire width of the nozzle air duct (4), said means being capable of ob-structing at least partially air flow from the air channel (2) via the nozzle air duct (4) to the nozzle.
2. An apparatus in accordance with claim 1, c h a r a c -t e r i z e d in that the cut-off means (8, 9) is a pressure hose.
3. An apparatus in accordance with claim 1, c h a r a c -t e r i z e d in that the cut-off means (5, 7) is a pressure-hose-operated flap.
4. An apparatus in accordance with claim 1, c h a r a c -t e r i z e d by a baffle (10), adapted to the middle of each nozzle air duct (4) and extending over the entire width of the duct (4), said baffle dividing the duct (4) in two parts, and by cut-off means (8, 9) adapted to both sides of the baffle (10.
5. An apparatus in accordance with claim 1, c h a r a c -t e r i z e d by air passages adapted to the cut-off means (5, 7), said passages being adapted to pass from one side of the cut-off means (5, 7) to the other side in order to air leakage from the air channel (2) to the nozzle (3) when the nozzle air duct (4) is shut off.
6. An apparatus in accordance with claim 1, c h a r a c -t e r i z e d in that there are two nozzles (3), said nozzles being adapted to mirror each other about the longitudinal axis of the air doctor.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI900186 | 1990-01-12 | ||
| FI900186A FI900186A (en) | 1990-01-12 | 1990-01-12 | LUFTKNIV. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2034074A1 true CA2034074A1 (en) | 1991-07-13 |
Family
ID=8529696
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2034074 Abandoned CA2034074A1 (en) | 1990-01-12 | 1991-01-11 | Air doctor |
Country Status (4)
| Country | Link |
|---|---|
| CA (1) | CA2034074A1 (en) |
| DE (1) | DE4100770A1 (en) |
| FI (1) | FI900186A (en) |
| SE (1) | SE9100083D0 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111889299A (en) * | 2020-07-30 | 2020-11-06 | 浙江科技学院 | High-transfer-performance thermal sublimation paper coating process and device |
-
1990
- 1990-01-12 FI FI900186A patent/FI900186A/en not_active Application Discontinuation
-
1991
- 1991-01-11 CA CA 2034074 patent/CA2034074A1/en not_active Abandoned
- 1991-01-11 SE SE9100083A patent/SE9100083D0/en unknown
- 1991-01-12 DE DE19914100770 patent/DE4100770A1/en not_active Withdrawn
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111889299A (en) * | 2020-07-30 | 2020-11-06 | 浙江科技学院 | High-transfer-performance thermal sublimation paper coating process and device |
Also Published As
| Publication number | Publication date |
|---|---|
| DE4100770A1 (en) | 1991-07-18 |
| FI900186A (en) | 1991-07-13 |
| FI900186A0 (en) | 1990-01-12 |
| SE9100083D0 (en) | 1991-01-11 |
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