APPARATUS FOR REGULATING THE THICKNESS OF A COATING ON SHEET MATERIAL
United States Patent 3683851
A round-rod scraper is used to regulate the thickness of a coating on paper. The scraper is carried in a holder which is attached to one end of a pivotally mounted lever whose other end is carried by a bracket. The bracket also carries a tube filled with compressed air bearing against the lever through the intermediary of a plurality of independently displaceable pressure elements. The bracket itself is capable of having its position adjusted with the individual pressure elements held in fixed positions relative to one another.
US Patent References:
Enclosed gravure fountain
Faeber - December 1951 - 2579181
Wiping blade for coating devices
Warner - June 1952 - 2598733
Doctor blade for coating machines
Montgomery et al. - November 1954 - 2695004
Doctor blade for paper coating apparatus
Warner - January 1956 - 2729192
Apparatus for smoothing coating materials on a paper web
Johnson et al. - December 1963 - 3113890
Enclosed gravure fountain
Faeber - December 1951 - 2579181
Wiping blade for coating devices
Warner - June 1952 - 2598733
Doctor blade for coating machines
Montgomery et al. - November 1954 - 2695004
Doctor blade for paper coating apparatus
Warner - January 1956 - 2729192
Apparatus for smoothing coating materials on a paper web
Johnson et al. - December 1963 - 3113890
Application Number:
05/115950
Publication Date:
08/15/1972
Filing Date:
02/17/1971
View Patent Images:
Export Citation:
Assignee:
Jagenberg-Werke AG Patentabteilung (Dusseldorf, DT)
Primary Class:
International Classes:
B05C11/02; B05C11/04; B05C11/02
Field of Search:
118/100,126,104 117/64R,64C,12A,12R,12M,12L,12FC 15/256.51
US Patent References:
Primary Examiner:
Kaplan, Morris
Claims:
What is claimed is
1. In an apparatus for regulating the thickness of a coating on a web of sheet material comprising a roll about which said web moves and a round-rod scraper extending transversely of said web against said roll and operating on the coating, the improvement which comprises a holder for said scraper, a lever carrying said holder and being pivotally mounted about a fulcrum parallel to said scraper so that the bearing of said scraper against said web may be varied, means for varying the bearing at spaced locations along said scraper, comprising a pressure displaceable member extending parallel to said holder, and a plurality of pressure elements independently displaceable perpendicularly to said holder to adjust the pressure longitudinally along said scraper through the intermediary of said displaceable member and said holder, said pressure displaceable member comprising a distensible tube positioned between said lever and said independently displaceable pressure elements so as to transmit the action of said elements to predetermined locations along said scraper, and said holder being provided with a C-shaped opening for receiving said scraper, the mouth of said C being slightly smaller than the diameter of said scraper, said opening being resiliently deformable so as to permit said scraper to be pushed into and removed from said opening.
2. An apparatus according to claim 1, including a bracket carrying said lever at a location spaced from said holder, said bracket also carrying said pressure displaceable member and said independently displaceable pressure elements.
3. An apparatus according to claim 2, including means for adjusting the position of said bracket and the elements supported thereby relative to said roll.
1. In an apparatus for regulating the thickness of a coating on a web of sheet material comprising a roll about which said web moves and a round-rod scraper extending transversely of said web against said roll and operating on the coating, the improvement which comprises a holder for said scraper, a lever carrying said holder and being pivotally mounted about a fulcrum parallel to said scraper so that the bearing of said scraper against said web may be varied, means for varying the bearing at spaced locations along said scraper, comprising a pressure displaceable member extending parallel to said holder, and a plurality of pressure elements independently displaceable perpendicularly to said holder to adjust the pressure longitudinally along said scraper through the intermediary of said displaceable member and said holder, said pressure displaceable member comprising a distensible tube positioned between said lever and said independently displaceable pressure elements so as to transmit the action of said elements to predetermined locations along said scraper, and said holder being provided with a C-shaped opening for receiving said scraper, the mouth of said C being slightly smaller than the diameter of said scraper, said opening being resiliently deformable so as to permit said scraper to be pushed into and removed from said opening.
2. An apparatus according to claim 1, including a bracket carrying said lever at a location spaced from said holder, said bracket also carrying said pressure displaceable member and said independently displaceable pressure elements.
3. An apparatus according to claim 2, including means for adjusting the position of said bracket and the elements supported thereby relative to said roll.
Description:
The invention relates to a device for regulating the coating thickness in the coating of continuous webs of sheet material such as paper, plastic or the like, by means of a round scraper bearing on the coated side of the web. Specifically, the invention relates to the design and principle of operation of the elements holding and actuating the round-rod scraper.
The coating of continuous webs of paper is generally done by applying the coating medium, disposed in a storage container, to the moving paper web by means of dipping, transfer and/or coating rolls, with the paper web initially receiving some excess of coating medium. Downstream of the coating device, in the direction of travel of the paper web, a round-rod scraper is disposed which extends across the entire width of the paper web and bears against the coated side of the paper web, its function being to hold back the excess coating medium received by the web, the coating thickness being determined by the magnitude of the bearing pressure. The round-rod scraper further serves to bring about the uniform distribution and leveling of the coating medium remaining on the web.
Such round-rod scrapers, which can be driven at any desired speed and in any desired direction of rotation, as dictated by the nature of the substrate material and of the coating medium and by the particular operating conditions, offer the advantage over conventional doctor blades equipped with fixed spreader knives that they avoid the formation of stripes on the coated side of the web which may be caused by fibers or other foreign bodies which may become lodged there.
Securing a uniform and adjustable bearing pressure for the round-rod scraper poses a problem, however, and this bearing pressure is the factor which determines the uniformity and quality of the coating. It is therefore very important that the round-rod scraper be made to bear, with respect to its longitudinal extension, with the desired pressure distribution within the various zones against the paper web supported by a roll. The prior-art mounting and bearing-pressure systems for round-rod scrapers fall short of being the perfect solution to this problem because they fail to provide the requisite elasticity for a perfectly uniform pressure distribution.
It is accordingly an object of the invention to provide a mounting and bearing-pressure system for a round rod scraper which offers assurance that the elasticity of the mounting and loading means for the round rod provides a maximum of adaptability.
This and other objects and advantages are realized in accordance with the present invention wherein the round rod scraper is carried in a holder which is pivotally mounted on an adjustable bracket. The holder is acted upon by a distensible organ carrying a pressure medium and likewise supported by said bracket, said distensible organ being acted upon by a plurality of pressure elements which are adjustable in known manner independently of one another relative to the direction of the round rod scraper. The arrangement is such that the holder receiving the round rod is fastened to the free end of one or more levers whose fulcrum is supported by the bracket.
Preferably, the holder has a C-shaped mouth smaller than the diameter of the round rod and is formed of an elastic or resiliently deformable material such as plastic or the like, whereby said round rod scraper can be pushed into and removed from said mouth of said holder.
The invention will now be described more fully with reference to the drawings, wherein
FIG. 1 is a schematic vertical section through the apparatus, and
FIG. 2 is a top plan view of the apparatus.
Referring now more particularly to FIG. 1, a paper web 1 coming from a coating apparatus (not shown) wraps itself around a counterroll 2, its coated side facing outward. Within the range of said counterroll, a round rod scraper 3 comes to bear against the coated side of the paper web 1. Depending on the nature of the coating medium, the round rod scraper 3 may be provided with a smooth or contoured surface. A drive (not shown) rotates the round rod scraper 3 preferably in the direction opposite to that of the paper web 1. A prism-shaped holder 4, constructed of an elastic or resiliently displaceable material such as plastic or the like, is provided with a C-shaped mouth or notch 5 which partially surrounds the round rod scraper 3, a cleaning felt 6 which extends over the entire length of the round rod scraper 3 being embedded in said notch. The separation of the lips forming the mouth 5 is somewhat smaller than the diameter of the round rod scraper 3, and this adequately secures the round rod scraper 3 in position while readily permitting it to be inserted and removed by virtue of the elasticity of the material of the holder.
The holder 4 receiving the round rod scraper is fastened to the free end of one or more levers 7 whose fulcrum 8 is supported by a bracket 9. In the upper part of said bracket 9, at the level of the holder 4, there is disposed a hose or tube 10, made of rubber or the like, to which compressed air is adjustably admitted and which bears against the upper end of lever 7, and hence the holder 4 carrying the round rod scraper 3. The hose 10 is mounted in known manner in a plurality of pressure elements 11 which are disposed side by side over the length of the round rod scraper and which are guided in a slide bar 17 connected with the bracket 9. The elements 11 can be displaced independently of one another by means of spindles 12 and handwheels 13 via the interposed flange bolts 18.
The precision adjustment of the round rod scraper 3 in the direction of the paper web 1 is achieved by rotating the spindle 12. For example, if the handwheel 13 and spindle 12 rotate in clockwise direction they advance to the left as seen in FIG. 1 and carry flange bolt 18 to the left. In turn, this moves the element 11 to the left in the slide bar 17. Locally this compresses the tube 10 slightly for the desired effect on holder 4 and round rod scraper 3 at the selected location. All of this is achieved against the action of coiled spring 20 which undergoes compression as the cap 21 of spindle 12 bears against the head 22 of flange bolt 18.
To release the pressure at a pre-determined location along round rod scraper 3, the handwheel 13 is rotated in counterclockwise direction. Under the influence of spring 20 the head 22 of bolt 18 moves to the right in FIG. 1 (in downward direction as viewed in FIG. 2) which results in movement of element 11 in the same direction.
In addition, the common bracket 9, to which both the round rod scraper 3 and the hose are indirectly fastened, is also constructed so as to be adjustable and fixable in position, so that regardless of the setting of the individual elements the device can be advanced and retracted as a unit by known means, such as the stationary spindle 23 and the guide 24. Moreover, the angular position of the body 9 can be varied around the fulcrum 25 and secured by means of the clamping screw 26.
In this fashion the pressure at individual locations along the round rod may be adjusted either to render uniform all pressures, and thus thicknesses of coating, or to render them non-uniform in predetermined fashion.
It will be appreciated that the instant specification and examples are set forth by way of illustration and not limitation, and that various modifications and changes may be made without departing from the spirit and scope of the present invention.
The coating of continuous webs of paper is generally done by applying the coating medium, disposed in a storage container, to the moving paper web by means of dipping, transfer and/or coating rolls, with the paper web initially receiving some excess of coating medium. Downstream of the coating device, in the direction of travel of the paper web, a round-rod scraper is disposed which extends across the entire width of the paper web and bears against the coated side of the paper web, its function being to hold back the excess coating medium received by the web, the coating thickness being determined by the magnitude of the bearing pressure. The round-rod scraper further serves to bring about the uniform distribution and leveling of the coating medium remaining on the web.
Such round-rod scrapers, which can be driven at any desired speed and in any desired direction of rotation, as dictated by the nature of the substrate material and of the coating medium and by the particular operating conditions, offer the advantage over conventional doctor blades equipped with fixed spreader knives that they avoid the formation of stripes on the coated side of the web which may be caused by fibers or other foreign bodies which may become lodged there.
Securing a uniform and adjustable bearing pressure for the round-rod scraper poses a problem, however, and this bearing pressure is the factor which determines the uniformity and quality of the coating. It is therefore very important that the round-rod scraper be made to bear, with respect to its longitudinal extension, with the desired pressure distribution within the various zones against the paper web supported by a roll. The prior-art mounting and bearing-pressure systems for round-rod scrapers fall short of being the perfect solution to this problem because they fail to provide the requisite elasticity for a perfectly uniform pressure distribution.
It is accordingly an object of the invention to provide a mounting and bearing-pressure system for a round rod scraper which offers assurance that the elasticity of the mounting and loading means for the round rod provides a maximum of adaptability.
This and other objects and advantages are realized in accordance with the present invention wherein the round rod scraper is carried in a holder which is pivotally mounted on an adjustable bracket. The holder is acted upon by a distensible organ carrying a pressure medium and likewise supported by said bracket, said distensible organ being acted upon by a plurality of pressure elements which are adjustable in known manner independently of one another relative to the direction of the round rod scraper. The arrangement is such that the holder receiving the round rod is fastened to the free end of one or more levers whose fulcrum is supported by the bracket.
Preferably, the holder has a C-shaped mouth smaller than the diameter of the round rod and is formed of an elastic or resiliently deformable material such as plastic or the like, whereby said round rod scraper can be pushed into and removed from said mouth of said holder.
The invention will now be described more fully with reference to the drawings, wherein
FIG. 1 is a schematic vertical section through the apparatus, and
FIG. 2 is a top plan view of the apparatus.
Referring now more particularly to FIG. 1, a paper web 1 coming from a coating apparatus (not shown) wraps itself around a counterroll 2, its coated side facing outward. Within the range of said counterroll, a round rod scraper 3 comes to bear against the coated side of the paper web 1. Depending on the nature of the coating medium, the round rod scraper 3 may be provided with a smooth or contoured surface. A drive (not shown) rotates the round rod scraper 3 preferably in the direction opposite to that of the paper web 1. A prism-shaped holder 4, constructed of an elastic or resiliently displaceable material such as plastic or the like, is provided with a C-shaped mouth or notch 5 which partially surrounds the round rod scraper 3, a cleaning felt 6 which extends over the entire length of the round rod scraper 3 being embedded in said notch. The separation of the lips forming the mouth 5 is somewhat smaller than the diameter of the round rod scraper 3, and this adequately secures the round rod scraper 3 in position while readily permitting it to be inserted and removed by virtue of the elasticity of the material of the holder.
The holder 4 receiving the round rod scraper is fastened to the free end of one or more levers 7 whose fulcrum 8 is supported by a bracket 9. In the upper part of said bracket 9, at the level of the holder 4, there is disposed a hose or tube 10, made of rubber or the like, to which compressed air is adjustably admitted and which bears against the upper end of lever 7, and hence the holder 4 carrying the round rod scraper 3. The hose 10 is mounted in known manner in a plurality of pressure elements 11 which are disposed side by side over the length of the round rod scraper and which are guided in a slide bar 17 connected with the bracket 9. The elements 11 can be displaced independently of one another by means of spindles 12 and handwheels 13 via the interposed flange bolts 18.
The precision adjustment of the round rod scraper 3 in the direction of the paper web 1 is achieved by rotating the spindle 12. For example, if the handwheel 13 and spindle 12 rotate in clockwise direction they advance to the left as seen in FIG. 1 and carry flange bolt 18 to the left. In turn, this moves the element 11 to the left in the slide bar 17. Locally this compresses the tube 10 slightly for the desired effect on holder 4 and round rod scraper 3 at the selected location. All of this is achieved against the action of coiled spring 20 which undergoes compression as the cap 21 of spindle 12 bears against the head 22 of flange bolt 18.
To release the pressure at a pre-determined location along round rod scraper 3, the handwheel 13 is rotated in counterclockwise direction. Under the influence of spring 20 the head 22 of bolt 18 moves to the right in FIG. 1 (in downward direction as viewed in FIG. 2) which results in movement of element 11 in the same direction.
In addition, the common bracket 9, to which both the round rod scraper 3 and the hose are indirectly fastened, is also constructed so as to be adjustable and fixable in position, so that regardless of the setting of the individual elements the device can be advanced and retracted as a unit by known means, such as the stationary spindle 23 and the guide 24. Moreover, the angular position of the body 9 can be varied around the fulcrum 25 and secured by means of the clamping screw 26.
In this fashion the pressure at individual locations along the round rod may be adjusted either to render uniform all pressures, and thus thicknesses of coating, or to render them non-uniform in predetermined fashion.
It will be appreciated that the instant specification and examples are set forth by way of illustration and not limitation, and that various modifications and changes may be made without departing from the spirit and scope of the present invention.