US2163712A - Coating machine - Google Patents

Description

June 27, 1939. w. v. SHEARER COATING MACHINE Filed April 22, 1938 2 sheets-sheet 1 INVENTOR WLTER VSHEARER BY ATTORNEYS June 27, 1939. w v SHEARER 2 ,163,712

COATING MACHINE Filed April 22, 1938 2 Sheets-Sheet 2 INVENTOR MATE? 767/5425? W01 ea ATTORNEY Patented June 27, 1939 UNITED STATES PATENT OFFICE OO ATING MACHINE Application April 22, 1938, Serial No. 203,523

4 Claims.

This invention relates to a machine for coating webs of paper and the like, and more particularly to a machine for coating such webs with a thermo-plastic material.

Substantial dimculties have been encountered in applying coatings of this character to webs of paper and the like. The coating must be applied at a relatively high temperature, it must then be brought to a smooth uniform surface before it sets sufficiently to be unworkable and the whole operation must be carried out with suiiicient rapidity to be commercially practical.

It is the object of my invention to provide a machine which will meet the above requirements a in commercial operation.

In the following specification my invention is described as embodied in a machine particularly adapted to the application of alkyl resin coatings, but it will be understood that its principles are go applicable to work with other similar thermoplastics.

In the accompanying drawings which illustrate one embodiment of my invention,

Fig. 1 is a side elevation of the machine;

35 Fig. 2 is a sectional view substantially on line 2-2 of Fig. 1;

Fig. 3 is' a sectional view substantially on line 3 3 of Fig. 1;

Fig. 4 is a detail plan view, on a larger scale,

39 of the drive for the doctor blade;

- Fig. 5 is a detail sectional view, on a larger scale, substantially on line 6-5 of Fig. 2; and

Fig. 6 is a detail sectional view, on a larger scale, substantially on line 6-6 of Fig. 3.

35 Referring to the drawings, in designates a table-like frame upon which the variousinstru- 45 pressed by a rubber covered roll is. Rolls l6 and ll are journaled in suitable brackets secured to frame It, the bearings of roll i9 being adjustably mounted in the brackets for movement toward and from roll l8 through a handwheel 2| 60 in a well known manner, whereby the degree to which the paper is pressed against roll I3 may be adjusted. I

I Roll I8 dips into a tank 23 containing the ther-' moplastic coating material. Both the roll l3 and 35 tank 23 are heated to maintain the coating material in a sufficiently fluid condition for proper operation. While any suitable heating means may be employed, I prefer to construct the tank with double walls forming a jacket and to circulate Dowtherm at desired temperature through 5 the roll and jacket. The preferred Dowtherm is an eutectic mixture of the organic compounds,

. diphenyl and diphenyloxide, the composition of the mixture being diphenyl (CsH5)z-26 /2%. and diphenyloxide (CaH5)2O--73 /2%. It is liquid at 10 ordinary room temperatures, freezes at 53.6 F. and boils at 500 F. at atmospheric pressure. The Dowtherm is supplied to the roll and jacket by pipes and 26, respectively, which connect to a supply line 21 leading from a boiler not 13 shown. The return pipes from the roll and jacket are shown in Fig. 2 at 23 and 23 respectively, which connect to a return line not shown. I have found Dowtherm of particular advantage in providing the relatively high temperatures re- 20 quired, and which must be uniformly maintained within quite narrow limits to secure a satisfactory product.

The printing or coating roll it is intaglio engraved to provide a plurality of small closely arranged pockets which deposit or print the coating material as a plurality of dots on the web as the latter passes over the roll. In order to control the depth to which the roll it! dips into tank 23 the latter is mounted as shown in Fig. 2 on vertical racks 33 reciprocably mounted in guides 3| mounted on frame to. Gears 32 secured to a shaft 3 engagethe racks 30 and shaft 33 is provided with a handwheel 34 by which shaft 33 may be rotated to raise or lower tank 23. The 35 supply and return pipes 26 and 29 are provided with flexible sections, one of which is shown at 35, to accommodate the adjustment of the tank.

The supply and return pipes 25 and 28 communicate with the interior of roll i8 through 40 shaft 33 on which the roll is secured and the latter is rotated in the direction of the arrow, ,Fig. 1, by a helical gear 33 secured to shaft 38 and meshing with a gear 40 secured to the main drive shaft 4i.

Surplus material is removed from the surface of roll l8 by means of a doctor blade 42 provided at its ends with studs 43 pivotally and slidably mounted in bearing guides 44 secured to brackets 20. The doctor 42 is reciprocated longitudinally of the roll by means of a link 46, one end of which is pivoted to the doctor at 41. The other end of link 46 is pivoted at 48 to a block adjustably secured in a slot 50 formed in a crank disk 5|. Disk 6| issecured to the upper end of a vertical shaft 52 journaled in a bearing bracket 58 and provided with a worm gear 5|. The latter meshes with a worm 55 secured to main drive shaft ll. The gear ratios are made such that the doctor 42 reciprocates at a relatively high rate of speed for reasons later pointed out. The doctor 42 is yieldingly held against the surface of roll I8 by any suitable means such as a weight 51 connected to one end of cables 58 which pass over idle pulleys 59, and are secured to the outer end of arms 6|! extending from the studs 43 of the doctor blade.

From the printing roll it the web passes beneath an idle guide roll 62 journaled in bearings 63 slidably mounted in arms 64 of spaced brackets 65 secured to the frame Ill. The bearings 58 are adjusted in desired position in the arms 64 by means of screws 89. From the idler 62 the web passes over a smoothing roll 88 journaled in the brackets 65. Roll 68 is interiorly heated by means of inlet and outlet pipes Ill and II entering the roll through its shaft I2 and connected to the previously mentioned system through which Dowtherm is circulated. The flow of Dowtherm through the rolls I8 and 58 is controlled by suit;- able valves 59 positioned in their inlet pipes. The roll 68 is driven in a direction reverse to that of the web travel, as shown by the arrow in Fig. 1, by means of a spiral gear I3 (Fig. 3) secured to one end of shaft I2, and driven from shaft ti through a variable speed gear unit indicated at it in Fig. 3. The extent of the surface of roll is engaged by the web may be varied by the vertical adjustment of idle roll 62.

Beyond the smoothing roll 68 is positioned a stationary smoothing unit generally indicated at it. This unit comprises a pair of spaced members 76 with which the coated surface of the web successively engages after leaving roll 68.

As best shown in Fig. 6, the members I5 have surfaces of varying curvature and depending on the angular relation of the members to the web make a greater or less surface contact with the web. The character of the action of the members I on the coating also varies with the angular position of the member, the spreading action as distinguished from a smoothing or burnishing action increasing when the members are moved clockwise, as viewed in Fig. l, to increase the action of the relatively sharp edge of the heel portion TI. The member I6 gives a very eflicient control of the coating operation, and while the angular setting of these members is rather critical their proper position is easily determined in any given case by observation of the coated surface.

The members I8 are secured by machine screws I8 to supporting bars 19 which in turn are carried by rock shafts 80 to which the bars are secured by machine screws Ill. The shafts 80 pivctally engage in bearing members 82 and are held in adjusted angular position therein by nuts 83 threaded on the ends of the shafts. The bearing members 82 are mounted on a shaft 84, the ends of which are supported in blocks 85 vertically slidable in arms 86 of bracket 55 by means of adjusting screws 91. Shaft 84 is held in adjusted angular position in the blocks 85 by nuts 89 threaded on the end of the shaft.

The members I6 are heated by electric heat-. ing units 90 positioned in bores 9I extending lengthwise of the members.

From the members 16 the web inclines downwardly and beneath a cooling drum 95. In its passage from members 16 to drum 95 the web passes over an auxiliary heating unit comprising two parallel spaced gas heating units 98 mounted on a bracket 91 extending from a block 98 slidably mounted in guides 99 and movable thereon by means of screws It!) whereby the distance of units 96 from the web may be adjusted. Gas is supplied to heaters 99 by flexible pipes ID! from any suitable source not shown. The flow of gas is controlled by valves I92 placed in the pipes I I.

Just prior to its contact with drum 95 the coated surface of the web is subjected across its width to a blast of cooling air delivered through a suitable conduit I03 by a blower I04. Drum 95 is journaled in suitable bearings formed in brackets I mounted on frame I0. Any suitable refrigerating fluid is supplied to the interior of the drum through pipes I08 from a source not shown. The web is drawn through the machine and around drum 95 by drawing rolls I08 and I09 between which the web passes from drum 95. Drum 95 and roll I09 are driven by suitable gearing, not shown, from shaft 4|. The bearings of roll I98 are slidably mounted in guides I I0 for adjustment toward and from roll I99 by means of screws III.

From rolls I08Iil9 the web passes around guide rolls M2 to any suitable wind-up mechanism.

Shaft 4| may be driven in any suitable manner, as shown, power being supplied through a series of V-belts from a motor, not shown.

Thermo-plastic coatings such as alkyl resins are quite difiicult to handle and require careful control at the various stages. The temperature of the material, its consistency at the various operations and its physical manipulation are relatively critical if a satisfactory product is to be obtained.

The material sets rapidly and there is atendency for blemishesand local inequalities in thickness to persist. For example, it is almost impossible under working conditions to prevent occasional particles of matter from lodging under the edge of the doctor blade 42 producing fine lines or scratches in the coating. These scratches are difficult to smooth out. I have found. however, that by reciprocating the doctor blade more rapidly with respect to the travel of the web than is common practice with conventional coatings, that the scratches, if and when they occur, assume a zig-zag path of substantial angularity and that under these conditions the scratches can be obliterated by roll 68 and members I6. I

It will further be seen that the temperature of the material at the time of its application and at each stage of its manipulation is under control and that the extent of contact of the web with roll 68 can be adjusted. The character of the manipulation by members I6 is also under the control of the operator. Further, controlled heaters 96 may be used when necessary to render the setting of the coating more gradual and pro duce a finer and glossier surface texture in the finished product.

By proper setting of tension rolls I5 and drawing rolls IOU-I09 the desired tension in the web may be maintained.

By suitably arranging the intaglio pattern on roll l8 the coating may be applied in stripes or patches of desired form as is sometimes desirable in coating labels or wrappers in web formylater to be cut to desired shape.

I claim:

1. A machine for applying thermo-plastic coatings to webs of paper and the like which comprises means to advance the web, a reservoir for the coating material, means to maintain the material in the reservoir at constant temperature, an intaglio printing roll for transferring material from the reservoir to the web, means to heat the printing roll, a doctor blade for removing surplus material from the printing roll, means to reciprocate the blade at a rate sufllcient to give substantial angularity to any streaks caused by foreign particles under the doctor blade, a reversely rotating heated smoothing roll engaging the coated surface of the web, a heated smoothing bar having a surface of varying curvature over which the web is drawn, means to adjust the area of engagement of the web with the smoothing roll, means to adjust the angularity of the smoothing bar with respect to the surface of the web, means to cool the coating on the web, and means to control the temperature of the web during its passage from the smoothing bar to the cooling means.

2. A machine for applying thermo-plastic coatings to webs of paper and the like, which comprises, means to advance the web, a reservoir for the coating material, means to maintain the material in the reservoir at constant temperature, an intaglio printing roll for transferring material from the reservoir to the web, means to heat the printing roll, a doctor blade for removing surplus material from the printing roll, means to reciprocate the blade at a rate suflicient to give substantial angularity to any streaks caused by foreign particles under the doctor blade, a reversely rotating heated smoothing roll engaging the coated surface of the web, a heated smoothing bar having a surface of varying curvature over which the web is drawn, means to adjust the area of engagement of the web with the smoothing roll, means to adjust the angularity of the smoothing bar with respect to the surface of the web, and means to cool the coating on the web.

3. A machine for applying thermo-plastic coatings to webs of paper and the like which comprises means to advance the web, a reservoir for the coating material, an intaglio printing roll for transferring material from the reservoir to the' web, a reversely rotating smoothing roll engaging the coated surface of the web and a common heating system for the reservoir, printing roll and smoothing roll through which Dowtherm is constantly circulated.

4. A machine for applying thermo-plastio coatings to webs of paper and the like which comprises means for advancing the web, means for applying the material in a hot plastic condition to the material in the form of small closely adjacent dot formations, reversely rotating means and stationary bar means for spreading the dots into a smooth thin coating and means to maintain the material in proper plastic condition from the time of its first application until the completion of the spreading operations.

WALTER V. BEAM.

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