US2094348A - Method of coating - Google Patents

Description

Se t. 28, 1937., v F. P. CARLSON 2,094,343

METHOD OF COATING Filed July 17, 1954 INVENTOR l a-sat as, 1937 1 Frank P. Carlson, New in, N. I. a Application July 17, 1934,.-8erlal No. 785,!

'IClllms.

7 This invention relates to coating devices and the process of coating sheet'material.

The principal objects of this invention are a' machine and a process whereby sheet work of any given characteristics may be coated and conveyed, without gripping the work, for the purpose of propelling it while being coated. r 'Another object of this invention is a process whereby work in the shape of individual, relatively soft, thin and pliable sheets may be simul taneously coated, propelled and stripped from the meanswhich apply the coating, without the use of grippers".

Another object of this invention is a process of coating and stripping work, and simultaneously propelling it without the use of gripping means, which consists of causing the work to adhere to a moving support. I I

Another object of this invention is a process of coating work, and simultaneously propelling it without the employment of grippers, which consists of causing the work to adhere to a mov-- ing support, while subjecting it to the coating operation.

Another object of this invention is a process of simultaneously coating and subjecting theworkQ to a blast of gaseous mediaunder pressure, for

the purpose of propellingitby a moving support.

Another objectof this invention is to provide in a device of this kind suitably operable work supporting and work propelling means, whereby the work is caused to temporarily adhere to, and/onto be retained by, or held or forced against a 'movable supporting surface, while being subjected to the coating operation, for the purpose of conveying the work during the coating operation, without the use of grippers.

A still further object of'this invention is to provide in connection with said work-supporting and work propelling means, stripping devices for separating the work, from said work-supporting 'means immediately after the coat-applying operation.

Another object of this invention is to provide a device of this kind, which is applicable for either what is known as "strip-gumming", strip-coating", or full surface coating", and which may be employed 'for one orthe other operation at will, with but a slight rearrangement of its parts. ,The foregoing and numerous other objects and advantages of the present invention will become more readily apparent fromthe ensuing description and the accompanying drawing, the latter illustrating in a purely diagrammatical form the principles and outstanding features of the present device, which drawing however is not intended to limit my invention in any way, but rather to serve for explanatory purposes only.

In the drawing:

(elm-.08) I Figure 1 is a diagrammatlcal side elevation of -the device, 1

Figure 2 is'a partial detail view of one form of a work supporting roller,

Figure 3 is another partial detail view of another form of a work supporting roller,

Figure 4' is a partial diagrammatical front elevation of a modified form of the device, similar to that, shown in Figure 1, in which a plurality of narrow coating applying rollers take the place of a single, long roller, 7

Figure 5 is a diagrammatlcal side elevation of a modified arrangement of my device, with some of the elements reversed in their order, as compared with the device shown in Figure 1,

Figure 6 is a diagrammatical side elevation of a simplified form of mydevice, and

Figure 7 is aside elevation of a still simpler agangement thereof, also in diagrammatical out- 1 es. 1

Before commencing with a detailed description of the device and of the new process of simultaneously coating, stripping and propelling work a without the use of grippers, it may be well to mention in acursory way the heretofore employed machines and methods in the coating industry.

The application of a coating such as adhesives, varnishesor colors upon sheet metal, cardboard or other similarly stiff, relatively hard materials is well known. Due to the stifi'ness'of the work its passage through the coating applying rollers is relatively simple and does not require any special means for gripping it, as the work issues from, or during its passage through the coating applying device. v When, however, relatively thinmaterial is to be handled, such as paper or other tissue which is soft and pliableand does not possess sufllcient stiffness ofitsown to enable it to pass unaided through the coating applying device, and by itself strip therefrom, the operation becomes rather complex. For this reason various kinds of grippers or marginal guide devices were employed. which necessarily leave unmistakable impressionsor marks upon the work. Such marks are unsightly and expose some of the undersurface which should be covered by the coating.

The above disadvantages are entirely overcome ably mounted relative thereto a smooth, hard j coating controlling roller II, which operates above the coating material -II, and is intended to return into well It unwanted or excess coating material picked up by roller It. By adjustingroller relative to roller I2 the thickness of the coating layer is determined.

Also in cooperation with roller l2 there will be seen a coating distributing or/and transfer roller l5, which is also made of hard, smooth material and which is also adiustably mounted as will become presently evident.

In operative connection with roller i5 is also the coating applying roller l6, which is covered by a resilient working surface II. This roller is adjustably mounted at I3 relative to a work supporting roller, located below.

Roller l5 issuppbrted in adjustable brackets II, which are pivoted about the center axis of shaft 20 of the coating applying roller l6, and may be swung about the latters circumference. This adjustability facilitates the positioning of roller l5 at proper relation to roller l2. The shaft 2| of roller i5, is mounted in an eccentric bearing 22 which facilitates the adjustment of roller l5 relative to coating applying roller l8. These adjustments of roller l5 relative to rollers l6 and I2 determine the proper thicknessof the coating film and govern the distribution of the coating over the surface of roller I6. I

Below roller it there is provided the work supporting roller 23, the center of which is offset relative to the center of roller It so that the plane passing through the centers of the two rollers 15' not perpendicular, but is inclined, for the purpose of assisting in the feed of the work.

Work supporting roller 23 is preferably made.

, ofa relativelyhard material and possesses a smoothly ground, highly polished work supporting surface. This surface may beIalt'ered as will A be explained presently.

. The work supporting roller 23 preferably operates within a vessel 24, partially filled with a moistening medium 25 which latter, in conjunction with the smooth surface of the roller, is intended to attract, cause the adherence of, and temporarily hold the lower face of the work, passing between rollers l6 and 23, for the purpose of stripping the upper coated face of the work from the applying roller 3, and for propelling the work, while being coated. In engagement with roller 23 there will be 'seen an adjustable scraper 23, provided with a resilient blade 21 in tensional contact with the smooth working surface of the roller. The scraper serves for governing the amount of medium 25 desired at the upper portion of the roller's surface.

Opposite and somewhat below the adjacent points between rollers i5 and 23 there will be observed a stripper 23, intended to separate the work from roller 23,. and to guide the work to wards conveyor 23'of the drying mechanism, indicated at 35. The latter comprises adjustable heaters 3| and adjustable heat retaining and defleeting members 32, which may be moved rela-, tiveto conveyor 29 at will.

In front of rollers l3 and 23 there is shown a work feeder 33, which is designed to deliver individual work sheets towards the rollers in close succession i. e. substantially edge to edge, or at minute intervals from one another.

In Figure 2 a work supporting roller23' is illustrated, the working surface vof which is provided with minute, vacuum cups orv depressions 34, showmexaggerated in the. drawing. The shape and depth of these depressions maybe altered, depending upon the type of work to be handled. These vacuum cups are. intended to enhancethe adherence of the work to the roller. lnwlilgure 3 another modified form of a work supporting cylinder 23" is seen in which the wall 35 is perforated, as indicated at 35. Within the cylinder there is stationarily mounted a vane 31 provided with a passage 38. The latter connects with a hollow center 33, and terminates at its upper end in a hollow enlargement 40, in engagement with the inner surface of the cylinder wall. The hollow interior of the vane is connected with a suction device (not shown) arranged without cylinder 23". As the cylinder wall passes over the enlargement 43 of the vane, apertures 36 are successively subjected to the influence of the suction created .within the vane, which suction will attract and temporarily hold the lower surface of the work piece W, whereby its upper surface is stripped from coating ap'plying roller I6. As the apertures pass enlargement 40 of the vane, the suction ceases and the work sheet is free to be stripped by stripper 23 from the lower, surface of the work and cause it to adhere to the roller sufficiently to pry the work away from coating roller l6. The medium' to be employed for m'oistening roller 23 must have theproperty of not afiecting the material-of the work. lprefer toemploy easily evaporative liquids, In

' cases where the material of the work becomes.

difficult to handle I employ for moistening roller 23 an adhesive substance, dissolved in suitable solvent. The attraction of the work by the roller may be greatly enhanced by. providing minute vacuum impression, as explained in connection with Figure 2.

From Figure 1 it will be evident that all of the 1 rollers are forcibly operated with one another by means of gears or other positive power transmitting means, and that I do not depend upon the friction engagement between the respectiye rollers. The same principle applies to the propulsion -,of conveyor 23, which latter is connected by means of a chain drive with work supporting roller 23. Also feeder 33 is operated correspondingly by positive means from the mechanism of the applying device, but at a surface speed somewhat lower than that of the latter. All of the positive transmissions between the working elements of this device are absolutely necessary for vthe reason that the surface speed of the work mustbe substantially equal to the surface speeds .of the applying and work supporting rollers, and of all other rollers employed in the'device. All equal surface speeds are indicated by arrows crossed with a single mark. The speed of the drier conveyor is somewhat greater and is marked by an arrow with two crossing marks.

The adjustability of roller ll relative to roller i2, and of roller il relative to rollers l2 and i3, and of roller l5 relative to work supporting roller 23 is highly essential for, firstly, controlling the amount and the thickness of the coating to be applied, secondly, for the even distribution of the tributor roller l5 somewhat shorter, so as to prevent the picking-up-and transferring to roller l6 of surplus coating material, usually gathering at the ends of pick-up roller I2.

From the foregoing the principal features of the device shown in Figure 1 become readily evident. Due to the construction of worksupporting roller 23 in either its smooth'design, as shown in Figure 1, or in its modified forms, as indicated at Figures 2 and 3, the lower face of the work is attracted and temporarily held against the work-supporting roller and thus pried away or stripped from the coating applying roller It. In this way any external gripping devices for the work are entirely eliminated; consequently the' coated surface remains uniform and is not marred in any place. Incidentally, by the elimination of grippers, the working speed of the device is increased to the highest possible degree, and is far greater than in any heretofore employed similar devices. In addition to the increased speed obtained with my device, its operation is continuous and extremely accurate, whereby a high degree of efficiency and a marked reduction in cost is assured. M Referring now to Figure 4, this illustration intended to show that a plurality of individual, relatively narrow applying rollers 4i may be employed instead of a long applying roller, such as shown in Figure 1 at I6. Of course the usual distributor roller 15? is required for transferring coating to, and distributing it over the individual applying rollers 4|. Beneath these rollers there is again illustrated a smooth work supporting. roller 23', which is partly immersed in a vessel 24' filled with a dilutedadhesive medium 25'.

The employment of individual, narrow applying rollers is particularly advantageous for what is known as strip coating? or strip gumming. This operation consists of applying a coating to either the edges or to narrow portions of the work in the form of coating strips. Needless to say, the principle of stripping the coated work from the narrow applying rollers remains the same as that explained in connection with Figure 1.

- The modified-form of my device shown in Fi ure 5 consists of the usual rubber covered coating coating is again governed by an adjustable con- .pickup roller 42, partially submerged in a coat-v ing material 43 within a tray 44. The. amount of trol roller 45, and-the coating is transferred by means of a transfer and distributing roller 46.

I a usual scraper 5|, and the work is stripped from .2- arranged in a. row. The work is fed in by feeder I 53 and isdelivered upon an auxiliary conveyor the work'supporting roller by stripper fingers 52,

54, from which it is transferred to a drying conveyor 55.

:Figure 1, the upper roller arrangement is re I As will be seen from this figure, compared with versed, in that the pick-up roller, the control roller.and the distributing roller are transferred to the right of applying roller 41, the purpose of which is to position the" rollers in such a way as to provide, what I term, a puddle 55 of the coating material which is to be maintained between v distributor roller 46, and applying roller 41. The

size of that puddle is controlled by adjusting roller 46, and is governed by the, consistency of the coating material. It is essential that applying roller 41, is generously supplied with the coating material so as to uniformly transfer it to the-work. In order to permit suflicient coating material to be transferred to the work, the applying roller must not bear too tightly against the work piece. Because of this requirement, the work supporting roller 48 is chiefly relied upon to move the work during the coating operation, in accordance with the afore explained principle of the present invention. The rest of the component elements of this .machine are practically identical with those explained in connection with Figure 1, with the exception of auxiliary conveyor 54,.which latter permits the handling of very short work pieces.

Obviously instead of a single, long applying roller 41, I may employ a plurality of narrow applying rollers, as those explained in connection with Figure 4. The advantage of the device in Figure 5 resides in the visible, readily controllable puddle 56, which can notbe maintained as satisfactorily in the construction shown in Figure 1'.

The modification illustrated in Figurefi simplifies the arrangement of the coatingsupply mechanism and has the added advantage of preventing the coating material from evaporating and becoming thicker during operation, and thereby affecting the uniformity of the coating layer upon the work. In this device the coating material is maintained in a closed vessel 51, from which it the proper tack, by means of which'the. work sheet is attracted to the work supporting roller and propelled thereby, thus being effectively stripped from the surface of the applying roller. A suitable feeder 56, stripper fingers 61, and a conveyor 68 complete the arrangement of this construction.

Referring now to Figure 7, the mechanism of my device in this illustration is still more condensed to the simplest elements, employing again the basic principle of my idea'of attracting the coated work to the moving support thereof in such a way as to cause it to travel, while being coated, without the employment of any gripping device, rollers, or similar means, intended to proml the workmechanically.

In this figure there is employed a closed vessel 69 adapted to contain the coating material,

which latter is conveyed under pressure through conduit ID to a nozzle", from which it' issues directly against-thework. Surrounding conduit I at'its vertical portion is a chamber 12, adapted to contain a gaseous medium under pressure, as

In every other respect I again rely I I for-instance compressed air. The lower end of the "chamber 12 is bifurcated, as shown at 13.-

These bifurcated ends are'equipped with small minute coating spray before reaching the work.

The position of the nozzle and of the openings 7 in the bifurcations 13 relative to the work is such, that the work piece is directly subjected to the pressure of the escaping gas, whereby it is thrust against the tacking surface of supporting roller 14, operating in liquid 15, contained in vessel 16.

The pressure of the gaseous medium or air is sufliciently high to press the work sheet against roller 14, so as to effect an intimate engagement between the lower face of the work and the tacking surface of the roller. The amountof the coating applied to roller I4 is governed by .a conventional, resilient scraper l1, and the work 3 is prevented from adhering to foller 14 by the usual stripper fingers 18. The work to be coated is delivered to the machine by a feeder I9, and the finished work is conveyed from the machine by conveyor 80.

In connection with the device illustrated in Figure I it is to be borne in mind that my device is primarily designed for handling work possessing practically no stiffness of its own. as has been stated before. One of the outstanding features of my invention resides in the fact that the finished work must not show any gripping'marks, or

1 for that matter, any other marks resulting from conveying the work through the coating mechanism. I have achieved this in every one of the designs illustrated in the drawing, irrespective of the properties of the work.

In Figures 6 and 7 I have indicated individual nozzles for spraying the coating material, which of coursewould have only a limited use for producing relatively narrow coating stripes upon the.

work. It is quite obvious however that the working capacity of the device may be considerably augmented by employing adequately designed nozzles for covering any width, while adhering to the same basic principle of my invention.

Referring again to the constructions illustrated in Figures 1, 4 and 5, in which applying rollers are employed, attention is called to the fact, that although I have stated that the surface speed of all rollers is practically the same, this is in fact not entirely so. I have found that much superior coating results are obtained when the surface speed of the work is slightly slower than the surface speed of the applying rollers.

The fact that the surface speed of the work,

as it is delivered by the feeder, is somewhat slower than that of the applying roller, prevents the formation of slight accumulations of coating material at the leading edge of the work; this is important inasmuch as I thus obtain an absolutely even coating over the entire coated, surface of the work.

Another important feature is to be noted in connection with the design shown in these three figures. Contrary to the assumption that when the machine runs idle, i. e. when the workpieces are spaced far apart, that the coating material will be transferred to the work supporting roller,

I and from the latter retransferred to the bottom face of the work, this is decidedly not the case since the coating layer transferred from the coata ing roller to the work supporting roller is wiped off, by the scrapers 21 and SI .of Figures 1 and 5.

In view of the fact that I have illustrated several modified forms of my invention, applicable to the same process, and achieving the same results sought by me, it is quite readily evident that my invention is capable of a great many changes, modifications, applications and improvements to meet any contingencies and consupport, without being gripped or otherwise engaged for the purpose of moving it, all within the broad scope'of my idea, as set forth in the annexed claims.

I claim: I

1. The process of coating material, substantially in sheet form, which consists of movably supporting it at one of its surfaces, subjecting its movable support to the influence of a readily evaporative moistening medium, controlling the thickness oi said medium so as to provide a friction and adhesion-producing, non-transferring film upon said support for temporarily attracting the material and thereby facilitating its propulsion, and applying a coating to the other surface of the material, while its supported surface is thus temporarily attracted.

2. The process of coating'material, substantially in sheet form which comprises movably supporting its undersurface applying to' its movable support a readily evaporative moistening medium, removing the excess of the medium from the support so as to leave a thin, adhesion and traction-producing, non-transferring film for temporarily attracting the undersurface of the material, thereby facilitating its propulsion, and-applying a coating to the upper surface of the material, while its undersurface is thus attracted.

3. The process of coating material as set forth in claim 2, and wherein the movable support is a cylinder having a highly finished supporting surface.

4. The process of coating material as set forth in claim 2, and wherein the movable support possesses an endless, highly finished supporting surface.

5. The process of coating material as set forth in claim 2, and wherein the movable support possesses an endless, highly finished supporting surface and wherein the application of the coating is made under pressure.

6. The process of coating relatively thin sheet material, possessing either little or no inherent body firmness, in a substantially close, continuous succession, simulating the coating of a continuous web, which consists of movably supporting the material at its undersurface, applying to its movable support an adhesion and tractionproducing moistening medium, removing the excess of such medium from the support so as to leave thereon a non-transferring readily evaporative thin film for temporarily attracting the undersurface of the material, thereby facilitating its propulsion and its subsequent stripping, and applying a coating to the upper surface of the material, while its undersurface is thus propelled, and before it is stripped for the purpose of being freed from the coating application.

'1. The process of coating as set forth in claim 6, and wherein the movable support is provided with an endless,'highly finished surface for re-.- ceiving the film of said medium.

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