US 3768438 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
I United States Patent 1 Kumpf Oct. 30, 1973 MACHINE FOR COATING SHEETS OF PAPER AND THE LIKE WITH LIQUID COATING MATERIALS  Inventor: Wilhelm Kumpf, No. 38, Am Anger,
Erlangen, Germany  Filed: Sept. 1, 1971  Appl. No.: 176,856
 Foreign Application Priority Data Primary Examiner-Henry S. Jaudon Attorney-Jacobs & Jacobs [5 7] ABSTRACT A machine for coating sheets of paper and the like with liquid coating materials, in which the sheets are conducted without the application of pressure between a smooth coating roller and a larger diameter format roller, preferably rotating at different peripheral speeds, for coating the entire surfaces of said sheets, a feed roller accepting the coating material from a fountain roller dipping into a supply of coating material and transferring a film of desired thickness to the coating roller. For applying the coating material to predetermined parts of the surfaces of sheets the smooth coating roller together with special chocks mounted in bearing supports is removable from the machine and replaceable by a screen roller provided with screen surfaces corresponding to the surfaces that are to be coated. The screen roller revolves at the same peripheral speed and has the same diameter as the format roller, besides being mounted in taller chocks adapted to its larger diameter, but insertable into the same bearing supports. A doctor blade cooperates with the screen roller attachable to existing fixing means. The format roller is designed to withstand the high roller pressures required for gravure printing.
6 Claims, 3 Drawing Figures MACHINE FOR COATING SHEETS OF PAPER AND THE LIKE WITH LIQUID COATING MATERIALS BACKGROUND OF THE INVENTION This invention relates to a machine for coating sheets of paper and the like with liquid coating materials, particularly with gloss or colored varnishes or adhesives. Coating the entire faces of sheets of paper usually presents no major difficulty. The coating material can be applied-in the same way as the ink in rotary printing presses by a system of rubber rollers. Substantially this system comprises a fountain roller which dips into a supply of the coating material and delivers the same through an intermediate transfer or feed roller in the form of a film of the desired thickness to a third roller which functions as a coating roller. The latter applies the material to the sheets which are conveyed through the gap between the coating roller and a cooperating counter-roller.
The counter-roller is analogous to a cylinder known in gravure machines as the format cylinder. It will therefore hereinafter be described as the format roller, because it likewise carries a rubber blanket underneath which a flat insert is placed of the same format as the sheet that is to be coated. The resultant raised backing for the sheet ensures that only the face of the sheet will be coated but that the remainder of the format roller will remain free of coating material.
However, contrary to gravure machines no pressure is exerted between the coating roller and the counterroller, since otherwise the film of varnish or the like would be squeezed out. The two rollers are adjusted to leave a gap sufficiently wide to permit the coating material to be applied to the sheet by light contact. A gentle rubbing motion of the coating material is in fact advantageous. Consequently the coating roller and the counter-roller are driven at slightly different peripheral speeds. Analogously, no contact pressure is created between the fountain roller, the feed roller and the coating roller. They are likewise placed close enough for the transferred lacquer or like film to have the desired thickness. Since none of the four rollers is required to withstand major stability stresses each may be a lightweight metal cylinder, the coating, feeding and fountain rollers being provided with polished rubber coverings. Moreover, in order to achieve a more uniform distribution of the coating material that is applied to the sheets the circumference of the rubber coating roller is also shorter than the length of the sheet or the circumference of the format roller.
Lacquering and like coating machines of the described kind for coating one complete side of sheets are known in the art. They work satisfactorily and can be produced at low cost so that their employment is economically justified although they are merely auxiliary surface finishing machines that have a low product value compared to that of printing machines.
However, frequently the need arises not only of coating one complete side of paper or like sheets with liquid materials, but also of coating only particular parts of the sheet surface, for instance in the application of coloring or gloss varnishes to paper that is to be used for packing, when certain surfaces are to be kept free of varnish to enable them to accept glue. Moreover, in order to economise in the consumption of say varnish, it is advantageous to coat only those portions of the surface that can later be seen, for instance in folding packages in which large parts of the paper surface are hidden.
In the printing art the inking of part of the surface of sheets is already done in color printing. For this purpose gravure machines are used in which the printing cylinder has a screen corresponding to the surfaces that are to be inked. An excess of ink is applied to these screens and the surplus is removed with a doctor. The ink which remains in the cells of the screen is then transferred to the sheet by the application of considerable pressure. Gravure machines of this kind are large and expensive rotary machines for the production of glossy magazines, books and the like. Their employment for partly coating sheets merely for the purpose of imparting to their usually previously printed surface a greater advertising appeal by the application of a gloss varnish or of providing certain portions with an adhesive would be entirely uneconomical. Machines for performing these latter tasks may cost only a small fraction of the investment cost of a gravure machine if they are to be economically acceptable.
It has also been proposed to solve the problem of coating part surfaces by using plate cylinders in which the surfaces that are to be coated in the same way as the plates in relief printing are in relief. However, difficulties arise in the distribution of the coating material, particularly at the edges of such plates.
SUMMARY OF THE INVENTION The invention seeks to improve the first hereinabove described machine that comprises a rubber roller system for coating the entire side of sheets, the object of the invention being to modify such a machine without major expense so that it can be converted into a machine for coating only predetermined portions of the surfaces of sheets. This makes the provision of a second independent machine for such a purpose unnecessary.
For achieving this object the present invention consists in that for applying a coating material to predetermined parts of the surfaces of sheets the smooth coating roller together with a pair of special chocks mounted in bearing supports is removable from the machine and replacable by a screen roller provided with screen surfaces corresponding to the surfaces that are to be coated, the screen roller revolving at the same peripheral speed and having the same diameter as the format roller, besides being mounted in a pair of taller chocks that are adapted to its larger diameter but are nevertheless insertable into the same bearing supports, a doctor blade cooperating with the screen roller being attachable to existing fixing means and the format roller designed to withstand the high contact pressures required in gravure printing.
Since the circumference of the smooth rubbercovered coating roller for coating the entire face of the sheets must be shorter than the length of the sheets, and also than the circumference of a screen roller, in order to ensure a uniform distribution of the coating material on the face of the sheet, the feed roller must be withdrawn when the machine is re-equipped. For this reason a useful feature of the invention consists in that the feed means for the coating material which in the conventional manner substantially comprise a fountain roller dipping into a supply of coating material, a feed roller accepting the coating material from the fountain roller and transferring the same as a film of the desired thickness to the coating roller, as well as adjusting means, are mounted as a unit assembly on a common frame portion which can be advanced and retracted a distance that makes allowance for the different diameters of the coating rollers that can be fitted into the machine.
BRIEF DESCRIPTION OF THE DRAWINGS These and other useful features of the invention will be understood as the following description of embodiments of the invention proceeds, in which reference will be made to the accompanying drawings which are illustrative schematic side elevations of essential parts of the proposed machine.
FIG. 1 is a machine for coating the entire surface of sheets by means of a rubber roller,
FIG. 2 is a machine for coating required parts of the surface of sheets, and
FIG. 3 is the coating machine according to FIG. 2 showing the sheet feed means in raised position.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the coating machine illustrated in FIG. 1 a roller 1 has a polished rubber covering. The purpose of this roller 1 is to apply a coating material to sheets that are conveyed from right to left in FIG. 1 through the gap between the coating roller and a cooperating counter-roller 2. The coating roller 1 obtains the coating material from a feed assembly marked 3 substantially comprising a fountain roller 4, a feed roller 5 and a fountain 6 for the coating material. The fountain roller 4 dips into the fountain and transfers parts of the material which it picks up to the feed roller 5 which transfers a desired thickness of film to the coating roller 1. Adjusting means 7 and 8 are provided to adjust the roller clearances and the required thicknesses of the film of material that is transferred from the fountain roller 4 to the feed roller 5 and from said feed roller to the coating roller 1.
The counter-roller 2 is a format roller. A rubber blanket 9 is wrapped around its circumference and clamped in position. Underneath the rubber blanket 9 is an insert which in size corresponds to the format of the sheet that is to be coated. This insert creates a slightly elevated backing for the sheet. Consequently the coating material will be applied by the coating roller 1 only to the sheet and not to other parts of the format roller 2.
The individual sheets are positioned in relation to the insert by conventional gripper feed means travelling in an endless path at the peripheral speed of the format roller 2. The gripper feed means comprise two chains 10 adjacent the side faces of, and driven by the format roller 2. They are mounted on cross members spaced between the chains 10 at equidistant intervals but not shown in the drawings. These grippers consecutively grip the sheets at the machine entry side, draw them through the gap between the two rollers 1 and 2 whilst being received into a longitudinal recess 11 in the format roller 2, and convey the sheets into proximity with a pair of return wheels 13 mounted some distance away on a cantilever frame 12, where the sheets are released.
There is no contact pressure between the coating roller 1 and the format roller 2, these two rollers being adjusted to the appropriate clearance for the coating to assume the required thickness. For this purpose the format roller 2 has a fine adjustment for elevation, as illustratively indicated in FIGS. 2 and 3 by an eccentric bearing 15 for the format roller shaft 16, and a worm 14 for rotating the eccentric bearing.
The diameter of the coating roller 1 is significantly less than that of the format roller 2. It has been found that the uniformity of the coating applied by the coating roller 1 is disturbed at higher speeds before it makes contact with the sheet if the diameter of the roller exceeds a given size. Coating roller 1 and format roller 2 also have slightly differing peripheral speeds to generate a gentle rubbing action of the coating material.
For changing the machine over from the described process of coating the entire surface of the sheets, as shown in FIG. 1, to coating only one or more parts of the surface of the sheets, the smooth coating roller 1 is removed and replaced by a screen roller of the same diameter, and driven at the same speed as the format roller 2. In order to facilitate dismantling and assembling the rollers the coating roller 1 is mounted in special chocks 17 which are received into ways 18 in bearing supports 19 which they are bolted to.
Referring to FIG. 2 in which the same reference numerals as in FIG. 1 identify like parts, the screen roller 20 which has replaced the smooth coating roller 1 (FIG. 1) is likewise mounted in suitable chocks 21. Owing to the larger diameter of the screen roller 20 these chocks 17 are higher than those shown in FIG. 1, but they fit into the same ways 18 of the bearing supports 19. The same holes can also be used for bolting the chocks in position.
The position of the feed roller 5 must be adjusted to the larger diameter of the screen roller 20. In order to simplify this operation it is useful to combine the entire feed assembly 3, substantially comprising the fountain roller 4, the feed roller 5 including the adjusting means 7 and 8, and the fountain 6 itself, in a single unit assembly. This may be mounted in a special portion 22 of the frame attached by screws 23 to its base. After undoing these screws 23 the entire multi-component feed assembly 3 can be moved back a suitable distance determined by tapped holes 24 for the reception of the screws 23.
The screen roller 20 is provided, directly on its surface or on a metal plate thereon, with a screen similar to that used in photogravure, the screen covering those parts which correspond to the parts on the sheets that are to be coated. In order to remove from the regions outside the cells of the screen the unwanted coating material which has been applied to the entire surface of the screen roller 20, a doctor 25 is used which is mounted, together with its holder, on fixing means 26. In the simplest case the latter may merely be tapped holes for the reception of fixing screws.
Whereas in a machine equipped with a rubber coating roller for coating the entire surface of the sheets the format roller is not submitted to contact pressure and may therefore be of light-weight construction, it is called upon, in the embodiment of the machihe according to FIGS. 2 and 3, to press the sheet against the screen roller with a considerable amount of pressure, as in gravure printing. The format roller 2 is therefore designed for withstanding such high pressures and remains in the machine even when the entire face of the sheet is to be coated and a rubber coating roller 1 (FIG. 1) is used.
Consequently, if it is desired to re-equip a machine using a rubber coating roller for coating the entire sheet surface for the purpose of coating only parts of the sheet surface, it is in practice only necessary, apart from one or two minor changes to be made in the machine itself, to provide an additional screen roller and a doctor, i.e., an expense which is in no way comparable to the cost of a second machine.
The change-over itself is likewise not very difficult and can be accomplished within a short time. The work can be significantly facilitated if the cantilever frame 12 carrying the pair of return wheels 13 can be hingeably raised. For this purpose the cantilever frame 12 which substantially consists of two sides that are connected together at suitable points may be hinged coaxially with the format roller shaft 16, either on this shaft itself or in a machine frame 27 in alignment therewith, the cantilever frame resting on supports provided on the machine frame 27 when in the working position shown in FIGS. 1 and 2. Lifting means, such as hydraulic ram cylinders 28 attached to each cantilever half, may conveniently be provided for raising the frame 12. To avoid the coating roller 20 or 1 (FIG. 1) being in the way, this roller may be retractable. For this purpose the bearing supports 19 may have extensions which carry the frame portion 22 supporting the coating roller assembly, the extensions forming a slide 30 movable in special ways in the machine frame 27. Two coupling rods 29 may be linked at one end to side members of the cantilever frame 12 and at the other end to the slide 30 in such a manner that when the cantilever frame 12 is raised the slide 30 will be automatically moved out of the way together with the assembly which it supports. When the cantilever frame 12 is raised the delivery side of the machine is fully accessible for the insertion and adjustment of the inserts on the format roller 2, for cleaning the rollers, exchanging the coating rollers 1 or 20 for inspecting, repairing and so forth.
The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The embodiments are therefore to be considered in all respects as illustrative and not restrictive.
What is claimed is:
1. A coating machine comprising (a) a frame, (b) a format roller rotatably mounted on the frame, (c) a pair of supportsmounted on the frame parallel to the axis of the format rollers and operable to receive chock elements, (d) a first roller and chock assembly comprising (i) a pair of chocks mountable in the supports and (ii) a coating roller rotatably mounted in its associated chocks and being of a diameter smaller than that of the format roller, the chocks of said first assembly being of a height sufficient to dispose said coating roller and said format roller in parallel coating aligment without contact pressure, and (e) a second roller and chock assembly interchangeable with the first roller and chock assembly and comprising (i) a pair of chocks mountable in the support and (ii) a screening roller rotatably mounted in its associated chocks and being of the same diameter as said format roller, the chocks of said second assembly being of a height sufficient to provide contact pressure between said format roller and said screen roller.
2. A coating machine as defined in claim 1 including (a) coating material feeding means detachably mounted on said frame, said means comprising (i) a fountain roller operable to dip into a coating material reservoir, (ii) a second feed roller accepting coating material from said fountain roller and transferring the same to a third roller, said third roller being either said coating roller or said screen roller, (iii) means for adjusting the distance between the fountain roller and feeder roller and (iv) means for adjusting the distance between the feeder roller and said third roller, and (b) means for moving said coating material feeding means from a first position on the frame when said first roller and chock assembly is disposed in said supports to a second position when said second roller and chock assembly is disposed in said supports.
3. A coating machine as defined in claim 2 wherein said feeding means includes a doctor disposed to engage the screening roller when said second roller and chock assembly is disposed in said supports but not the coating roller when said first roller and chock assembly is disposed in said supports.
4. A coating machine as defined in claim 1, including stock feeding means, said feeding means comprising two endless chains with grippers mounted thereinbetween, said chains running at one end over chain wheels disposed coaxially with the format roller and at the other end over chain wheels disposed away from the delivery side of the rollers, said chain wheels being mounted on a cantilever frame which is hingeably raisable coaxially with the axis of the format roller.
5. A coating machine as defined in claim 4, wherein the supports and feeding means are slideably mounted on the frame.
6. A coating machine as defined in claim 5, wherein the cantilever frame is coupled to the feeding means and supports so that raising the cantilever frame about its hinge displaces the support and feeding means from their working position and lowering the cantilever frame returns the support and feeding means to their working position.