US2500041A - Apparatus for changing coating solutions of coating machines - Google Patents

Description

March 7, 1950 Filed Sept. 28, 1945 P. MOREY 2,500,041 APPARATUS FOR CHANGING COATING SOLUTIONS OF COATING MACHINES 2 Sheets-Sheet 1 FIG].

LEON P. M OREY INVENTOR j: ATTORNE S March 7, 1950 L. P. MOREY 2,500,041

APPARATUS FOR CHANGING COATING SOLUTIONS OF COATING MACHINES Filed Sept. 28, 1945 2 Sheets-Sheet 2 FIG. 5.

LEON P. MORE) INVENTOR BY W M ArroRNmzs Patented Mar. 7, 1950 UNITED STATES PATENT OFFICE APPARATUS FOR CHANGING COATING SOLUTIONS OF COATING MACHINES Leon P. Morey, Rochester, N. Y., aollgnor to Eastman Kodak Company, Rochester, N. Y.. a corporation of New Jersey Application September 28, 1945, Serial No. 819,031

18 Claims. (Cl. 91-46) The present invention relates to the art of coating a continuous web, and particularly to an apparatus for replacing a pan of coating solution with another very rapidly without causing a noticeable agitation in the surface of the solution in the pan moving into coating position.

In known coating procedures the supply of coating solution is contained in a pan from which it is taken directly by the web be'ng immersed therein or by an applicator, or pick-up, roll immersed therein. In all instances the pan is constantly supplied with solution to maintain the level of the solution in the pan constant, or Practically so. In the well known immersion method of coatng, the constancy of this level in the coating pan is very critical as to the thickness of coating supplied to the web and elaborate steps are taken to maintain the level in the coating pan constant. It is also imperative that the surface of the supply of coating solution be absolutely free of ripples at all times since such ripples have the same effect as changes in the level of the coating solution, namely, cause changes in thickness of the coating being applied to the web.

It is oftcn desirable, or necessary, for a number of different reasons, to change a given coating solution for a new one, and it is desirable to be able to do t is without shutting down the machine, and particularly without stopping the feed of the web; because this necessarily means a cut in production. At present, a change of the coating solution necessitates a shut-down of the machine and a compl te cleaning of the coatin pan and refilling it with the solution which takes a conslderable time. The reasons for changing the coat ng solution are too numerous to completely list herein but a few representative ones might be mentioned. First, the most obvious one is to substtute an entirely different coating solution for the one being used. Secondly, certain solutions, despite the fact that they are vigorously agit ted and repeatedly added to, change in physical and chemical properties with time and have to be thrown away and replaced by a new batch. Thirdly, the solution might become contaminated in some way during the coating operat on which would mean a complete clean-up oi the coating pan.

One object of the present invention is to provide for interchanging coating solutions by having two or more coating pans which can be filled with the desired coating solution. and substituting one complete pan for another when it is desired to change the coating solution.

Another object is to provide an arrangement 2 wherein the several coating pans are movable between a coating position and a ready position, and whereby two pans can be interchanged rapidly and simultaneously with no eflort on the part of the operator except to push a switch button.

And yet another object is to provide an arrangement whereby one coating pan is removed from, and another is moved to, the coating position rapidly and simultaneously so that no stopp e of the web feed is required.

And still another object is to provide a coating pan interchange mechanism which moves a coating pan to the coating position in such a way that no disturbance of the solution of the pan is caused which is detectable in the quality of the final coating of the web. In other words, the constant liquid level is maintained in the pan at all times or is present by the time the pan reaches the coating position.

And another object is to provide a. pan interchange mechanism in which there is substantially a static balancing of the pans and the operating linkage therefor in all positions of movement.

And another object is to provide a Dan interchange mechanism which is driven by a cam the curve of the working face of which is such as to impart uniform acceleratin and decelerating motions to the pans during the interchange.

And a further object is to provide a pan interchange mechanism in which the coating pans are positively located in the coating position by the cooperation between adjustable stop screws and lugs on the pans and machine frame, and the drive linkage for the pans includes a resilient coupling which permits the drive to proceed after the pan is positively stopped by the screws and lugs, and whereby the pans are held in this position by the resiliency of said coupling to account for any play or backlash between the pans and their driving linkage.

And another object is to provide a reversible motor drive for said pan interchange mechanism which is started by manual operation of a switch and which is automatically stopped when a coating pan reaches the coating position.

The novel features that I consider characteristic of my invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its additional objects and advantages thereof, will best be understood from the following description of a specific embodiment when read in connection with the accompanying drawings in which,

Fig. 1 is an end view of a preferred embodiment of the driving mechanism for the coating pan interchange mechanism.

Fig. 2 is a vertical cross-section showing one end of the pan interchange mechanism, and particularly the guide tracks for the pan and the lever and linkage system for moving said pan in said guide tracks.

Fig. 3 is a front view, partly in section, of the complete interchange mechanism.

Fig. 4 is an enlarged detail of a portion of Fig. 2, and showing the cooperation between adjustable stops on the pan supporting brackets and lugs on the machine frame to accurately position the pans in the coating position, and

Fig. 5 is a vertical section taken substantially on line 55 of Fig. 4.

Like reference characters refer to corresponding parts throughout the drawings.

In general, the present invention comprises the provision of two separate coating pans which are so mounted on the machine frame as to be simultaneously interchanged between a ready position and the coating position. The pans are supported and moved by a lever and linkage mechanism which is in turn set in motion by a cam driven by a reversible motor. The contour of the cam is such as to impart a uniformly accelerating and decelerating motion to the pans in moving to the coating position so that agitation of the solution in the pan is negligible. To further reduce the possibility of such agitation of the coating solution the pans and the operating lever and linkage therefor are statically balanced, and the slope angle, relative spacing and upper curved ends of the guide tracks for the pans are carefully selected. The pans are located in a definite coating position through the cooperation of adjustable stop screws on the pan supporting brackets with lugs on the machine frame, and the operating mechanism for the pans including a resilient coupling to account for the action of the'pan positioning means.

For purposes of disclosure I have shown my coating pan interchange mechanism in association with a coating machine of the immersion type for which it was particularly designed, but it will be understood by those skilled in the art that it could be used in connection with other well-known coating procedures, such as the applicator or pick-up roll type, if desired.

In the immersion method of coating, the web to be coated is fed over a roller, immersed in the supply of coating solution held in the coating pan, and the coating is prevented from contacting the back of the web by the use of safe edge cups, or the like, as is well known. In accordance with the present invention, the coating apparatus is provided with at least two coating pans l0 and I0 which are each movable between the coating position and a ready position rapidly and simultaneously. In the drawings, particularly Fig. 2, the coating pan [0 is shown in the coating position and in which position the conventional immersion roll I I, about which the web W to be coated is fed, is immersed in the coating solution. The other coating pan I0 is shown in its ready position which is below and to the right of the coating position, and in which position it can be readily cleaned and refilled ready for use while the coating operation is proceeding from pan I0. When it is desired to change the coating solution for any reason, the interchange mechanism hereinafter described is operated whereupon pan Ill moves to its ready position dotted l6 (looking at Fig. 3).

4 left of the coatingposltion, while at the same time pan 10 with its supply of new solution moves to the coating position.

As is well known to those skilled in the art, the quality, and particularly the thickness, of the coating applied to the web varies with the depth of immersion of the roll H into the coating supply, and, therefore, upon the level of the coating supply being maintained constant and undisturbed. Therefore, the coating pan being moved into coating position must be moved in such a manner that the surface of the coating supply therein is not agitated in any way because the web moves continuously during the pan interchange and coating starts immediately upon the solution in the pan touching the web. This problem becomes more impressive when it is considered that this interchange of pans must be made very rapidly to cut the amount of uncoated web to a minimum. The pan interchange mechanism I have invented, and will now describe, has been designed to interchange the coating pans in two seconds without causing an agitation in the surface of the coating solution which can be detected by examining the quality of the coating applied to the web.

To either end of each pan is fastened, in any suitable manner, as by welding, a supporting bracket l2 of the shape best shown in Figs. 2 and 4. Each of the supporting brackets carries a pair of supporting rollers I3 which travel in inclined guide tracks or grooves I4 located in guide plates [5 mounted solidly on the vertical machine frames l6. These guide tracks serve to guide the coating pans between the coating position and their respective ready position, and it is pointed out that while the major portion of each track is straight the upper end of each track is curved upwardly on a comparatively short radius termi nating in a very short section of vertical track. By this arrangement the final increment of motion of the pan moving into coating position, before it comes to rest, is vertical. The are of motion ending in a vertical motion is part of the control exercised over the liquid in the pan to prevent agitation thereof.

The two coating pans are moved simultaneously from one end of the guide tracks to the other end, or to and from the coating position, by a simple lever and linkage arrangement which is rugged and positive in action, desgned to facilitate smooth and easy motion of the pans, and ,adaptable to accurate positioning of the pans in the coating position. This lever and linkage arrangement includes a main operating shaft l1 extending horizontally below the coating pans and having its opposite ends journaled in the machine frames [6. Located on shaft I! in spaced relation are two bellcranks l8. One arm IQ of each bell crank has a link 2a pivoted thereto and a supporting bracket 2 for pan l0, while the other arm 2| of each bellcrank has a link 22 pivoted thereto and a supporting bracket l2 of the pan H). A rotation or oscillation of approximately 60 degrees of the shaft I! in either direction moves the one pan from coating position to its ready position and simultaneously moves the other pan from its ready position to the coating position.

The driving means for the main shaft ll comprises a cam disk 33 rotatably mounted on a stubshaft 24 mounted on the left-hand frame This cam disk 23 has a compound spiral cam groove 25 in its face the line positioned mm. 2) below and to the rise "1" of which. see Fig. 1, is sufficient to cause an oscillation of shaft II which will shift the two coating ans between their ready positions and the coating position. The cam is connected to the shaft I1 by a lever 28 mounted on the shaft and including a follower on its free end in the form of a roller 21 which extends into the cam groove 25.

On the periphery of the cam disk 23 there is fixed a ring gear 28 which meshes with a spur gear 29 mounted on the shaft of a reversible electric motor M which is operated-by a doublethrow switch 30. The respective circuits of the motor include normally closed limit switches 3| and 32 which are adapted to be opened by moving a roller carrier arm 33, forming a part thereof, to open the switch and break the motor circuit. Also adjustably mounted on the face of said cam disk is a limit switch operating plate 34 which extends beyond the periphery of the disk by a suillcient amount to contact the arms 33 of the limit switches to open the same.

When the main motor switch so is thrown to the position shown in Fig. l, the circuit containi limit switch 3| is energized and the cam is rotated counterclockwise by the motor M driving through the gears. This drive continues until the limit switch operating plate 34 opens the limit switch 3i to stop the motor (the condition shown in Fig. l) which is just before the follower 21 reaches the inner end of the cam groove; and by this time the coating pan It has been moved to its coating position. When the motor switch 30 is operated to close the other motor circuit (containing limit switch 32) the motor is started in the other direction and the cam rotates in a clockwise direction until the limit switch operating plate 34 opens limit switch 32 which stops the 'motor just before the follower 21 reaches the other end of the cam groove 25. Such a motion of the cam would cause the pan- If! to be moved to its ready positionand would cause the pan Ill to be moved to the coating position.

The curve of the cam groove is designed to move the coating pans in such a manner that the sway of liquid generated by the accelerating motion as the pans start is counteracted and eliminated by the decelerating motion as the pan stops. The curve of the cam groove is such that the maximum acceleration and velocity of the pans is found at the intermediate portion of their travel between their two positions and the rise of the'portion of the groove adjacent each end is very slight so that the pans in moving into coating position actually are traveling at a very slow rate. This eliminates a sudden stopping of the pan moving into coating position which would set up an agitation of the solution in the pan. With the arrangement shown it is possible to interchange the coating pans in the short time of two seconds without causin a noticeable agitation of the solution in the pans.

It will be appreciated that provision must be made for continually adding to th coatin supply in the coating pan which is in coating position as the web takes it away in order to maintain the level of the solution in the pan constant. Such a source of coating supply must also be available in order to fill the pan which is in ready position. When the coating is of a certain type it may be necessary to continually keep it at a constant temperature in which case the coating pan will have to be water-jacketed and be continually fed with a thermostatically controlled supply of water. In any case, since these features constitute no part of the present invention it has not been deemed necessary to encumber the present drawings and specifications with such a disclosure. It will suffice to say that it has been found satisfactory to provide each of the two coating pans with independent and flexible feed lines of any nature that might be desired and to move the complete unit between the ready and coating positions. In this connection, means are provided for automatically cutting off the services of the lines on the one pan as it leaves the coating position, and cutting on the services of the lines on the other pan as it moves into the coating position.

In the immersion method of coating it is imperative to a uniformgiven thickness of coating that the immersion roll be immersed a given amount in the solution of the pan. This, therefore, means that the coating position of pans must be accurately controlled. Since it would be impractical from a mechanical point of view to depend upon the cam groove and associated linkage to accurately position the pans in the coating position the following structure is provided for this purpose.

On each end frame I 6 there is located two stop lugs 36 into engagement with which a pair of for.

adjustable stop screws 31 carried by the pan supporting brackets I2 come to definitely locate the pans as they move into the coating position. By initially adjusting the height of the screws 31 the pans can be accurately leveled and in the same way a play in the driving mechanism due to wear or the like can be taken up and accounted The parts are so designed and the screws so adjusted that the pans always reach their coating position just before the cam drive stops and always before the cam follower reaches the end of the cam groove. To permit this condition to exist without distorting the linkage or stalling the motor, a resilient coupling is introduced in the pan changing mechanism between the cam and the links engaging the same. One form oi resilient coupling which serves the desired purpose and is very simple is that shown in Fig. 2. The bell cranks iii are each rctatab y mounted on a shaft ii and are connected thereto by a pair of leaf springs 38, one adjacent each end of the pan, which are each fixed at one end 39 to the shaft and extend radially therefrom between two rollers 40 and 4! fixed to and extending from a web 42 connecting the two arms of the bellcrank. Thus, as the shaft is rotated clockwise by the cam, the spring 38 will press against roller 45 and drive the bellcrank to the right to move pan ill into the coating position, as s own in Fig. 2, and in the opposite direction the spring acts against roller 40 to drive the other coating pan into coating position. The springs 38 should be of such gauge or strength as to act as rigid driving members so long as the coating pans are free to move, but just as soon as the pans are positively stopped and located in the coating position by the engagement between the adjustable stop screws 31 and lugs 36 the slight over-travel of the cam drive causes the springs to flex, as indicated by the d tted line position in Fig. 2. This resilient coupling, therefore, in addition to permitting a slight over-travel in the cam drive, and an accurate positioning of the coating pans in the coating position, acts to normally urge the stop screws against the stop lugs and thereby account for any play which might appear in the linkage between the links 20 and the coating pan supporting brackets and bellcrank arms.

The same resilient coupling action could be obtained by placing a resilient coupling between the lever 26 and the shaft I! if desired, but the present arrangement has been shown because of its simplicity. This modified arrangement would consist of rotatably mounting the lever 26 on the shaft I], rather than keying it thereto as in the present arrangement, providing a second lever keyed to the shaft l1 and inserting a resilient coupling between these two levers which would act as a rigid coupling up to a load encountered by free movement of the pans, but which would give when the pans were positively obstructed in their movement as by the engagement between the adjustable screws 31 and the lugs 35.

The design of the levers, links, tracks and supporting brackets is such that there is a balance of forces, due to the weight of the pans and all working parts, when expressed as a resultant torque on the shaft 11. This balance is maintained in all positions of the two pans except their stationary position, when the ready pan exerts approximately per cent more torque on the shaft l'l than the pan in the coating position. The design of all parts is also such as to secure the minimum of backlash or lost motion. The location of the rollers i3 carrying the weight of the pans is such that force is exerted on the tracks by the rollers to form a couple in all positions, and hence there can never be any backlash at these positions.

Referring to Figs. 2 and 3, it will be noted that when one of the pans is in the coating position the rollers l3 on the brackets i2 do not come completely to the end of the guide tracks 14. This indicates that the tracks are not supporting the pan which is in the coating position, but the weight of the pan is suppcrted solely by the link 20 or 22 and the arm of the bellcrank to which it is connected. In this position, the sides of the tracks merely support the pan against sidewise movement. It will thus be seen that the force of gravity will tend to move the pan from coating position the moment the cam drive is started so that the starting load on the motor will be reduced to a minimum. This arrangement of parts, therefore, gives a smooth, steady motion to the pan in both directions and requires a relatively low power output of the motor considering the total mass under motion. steadiness of the load tends to eliminate all minute fluctuations in velocity which might cause ripples in the surface of the coating solution.

From the above description it will be appreciated that four factors have been taken into consideration in the design of this equipment which in combination contribute to the resultant motion of the coating pans from their ready position to the coating position with a negligible agitation of the solution in the pans despite a rapid interchange. They are: (1) static balancing of the pans and operating linkage therefor, (2) practical elimination of all play in the mechanism due to wear and machining tolerances, (3) the slope angle, relative spacing and curved upper end of the guide tracks, and (4) the uniformly accelerating and decelerating motion imparted to the pans by the compound curve of the cam groove.

although I have shown and described certain specific embodiments of my invention, I am fully aware that many modifications thereof are possible; My invention; therefore, is not to be limited to the precise details of construction shown and described but is intended to cover all modi- 8 flcations coming within the scope of the an pended claims Having thus described my invention, what I claim is new and desire to secure by Letters Patent of the United States is:

1. In a web coating apparatus the combination of a pair of coatin pans adapted to contain a supply of coating solution and each movable between a common coating position and a ready position, and means for rapidly and simultaneously moving one of said pans from the coating position to its ready position while moving the other pan from its ready position to the coating position without causing an agitation of the liquid level of the solution in the pan moving into coating position suflicient to affect the quality of the coating applied to the web.

2. A coating apparatus according to claim 1, including two sets of stationary tracks. one set for each pan, and rollers associated with each pan engaging the set of tracks corresponding to said respective pans for guiding the pans between the coating position and their ready position.

3. A coating apparatus according to claim 1 in which the ready position of each pan is to one side of and below the coating position; one set of inclined tracks for guiding one pan between its ready position and the coating position; a second set of inclined tracks for guiding the other pan between its ready position and the coating position; rollers associated with each pan to move therewith, the rollers associated with one pan engagin one of said sets of tracks and the rollers associated with the other pan engaging the other set of tracks; the upper end of each track terminating in a portion which is vertical, whereby the final increment of motion of the pans before coming to rest in the coating position is vertical to assist in preventing agitation of the liquid level of the solution in the pans.

4. A coating apparatus according to claim 1 including two sets of inclined tracks for guiding the pans between their ready position and the coating position; one set of tracks for each pan; rollers associated with each pan to move therewith and engaging the set of tracks corresponding to the pan with which they are associated; an oscillatable bell crank; a link pivoted between the end of one arm of said crank and one pan, and a link pivoted between the end of the other arm of said crank and the other pan; and means for oscillating said bell crank between two positions to move said pans to and from said coating position.

5. A coating apparatus according to claim 1 including two sets of inclined tracks for guiding the pans between their ready position and the coating position; one set of tracks for each pan; rollers associated with each pan to move therewith and engaging the set of tracks corresponding to the pan with which they are associated; an oscillatable bell crank; a link pivoted between the end of one arm of said crank and one pan, and a link pivoted between the end of the other arm of said crank and the other pan; and a reversible electric motor for oscillating said bell crank between two extreme positions in each of which opposite ones of said pans are moved into the coating position.

6. A coating apparatus according to claim 1 including two sets of inclined tracks for guiding the pans between their ready position and the coating position; one set of tracks for each pan;

rollers associated with each pan to move there- 9 with and engaging the set oi tracks corresponding to the pan with which they are associated; an osc llatable bell crank; a link pivoted between the end of one arm of said crank and one pan. and a link pivoted between the end of the other arm of sa d crank and the other pan; and a reversible electric motor for oscillating said bell crank between two extreme pos tions in each of which a different one of sa d pans is moved into the coating position. a manual switch for starting said motor; and means for automatically breaking the motor circuit when one of the coating pans reaches the coating position.

'7. A coating apparatus according to cla m 1 includin two sets 01' inclined tracks for guiding the ans between their ready position. and the coating position: one set of tracks for each pan; rollers assoc ated with each pan to move therewith and engaging theset of tracks corres onding to the can with w ich th y are associated: an osc llatable bell crank; a link pivoted between the end of one arm of sa d crank and one pan, and a link pivoted between the end of the other arm of sa d crank and the other pan: and means for oscillating said bell crank between two positions to move said pans to and from said coat ng po ition, said last ment oned means be ng' such as to give the pans a decelerating mot on as they come to a stop to counteract the sway generated in the liquid by the accelerated motion as the pans start to move.

8. A coating apparatus according to claim 1 including two sets of inclined tracks for guid'ng the pans between their ready position and the coatng position; one set of tracks for each pan; rollers associated with each pan to move therewith and engaging the set of tracks corresponding to the pan with which they are associated; an osc'llatable bell crank; a l nk pivoted between the end of one arm of said crank and one pan. and a link pivoted between the end of theot-her arm of said crank and the other pan; and means for oscillating said bell crank between two positions to move said pans to and from said coating pos tion, said last mentioned means including an osc'llatable cam the contour of wh ch is such as to give the pans a decelerating motion as they come to a stop in order to counteract the sway generated in the liquid by the accelerated motion as the pans start to move.

9. A coating apparatus according to cla m l. including two sets of inclined track for guid ng the pans between the'r ready position and the coating pcsit cnz one set of tracks for each pan; rollers associ ted with each pan to move therewith and engaging the set of tracks corresponding to the pan with which they are assocated; an oscil atable bell crank; a link pivoted between the end of one arm of said crank and one pan, and a link pivoted between the end of the other arm of sa d crank and the other pan; and means for oscillating said bell crank between two positions to move said pans to and from said coatin position, said last mentioned means including an oscillatable cam the contour of which is such as to give the pans a declerating motion as they stop in order to counteract the sway generated in the liquid by the accelerated motion as the pans start to move; a reversible motor for driving said cam in opposite directions; a pair of limit switches in said motor circuit; and a switch operating member associated with said cam to move therewith and adapted to alternately actuate said limit switches to automatically stop said motor when one of said pans is moved to the coating position.

10. A coating apparatus according to claim 1 including two sets of inclined tracks for guiding the ,pans between their ready position and the coating position; one set of tracks for each pan; rollers associated with each pan to move therewith and engaging the set of tracks corresponding to the pan with which they are associated; an oscillatable bell crank; a. link pivoted between the end of one arm of said crank and one pan, and a link pivoted between the end of the other arm 01' said crank and the other pan; and means for oscillatin said bell crank between two positions to move said pans to and from said coating position, said last mentioned means including an oscillatable shaft to which said bell crank is fixed to be oscillated thereby; an oscillatable cam; a lever fixed at one end to said shaft and including a follower on the other end engaging the working face of said cam; the rise of said cam being such as to oscillate said shaft a sufllcient amount to move said pans between their two positions, and the contour of said cam being such as to give the pans a decelerating motion as they stop to counteract the sway generated in the liquid by the accelerated motion as the pans start to move.

11. A coating apparatus according to claim 1 including two sets of inclined tracks for guiding the pans between their ready position and the coatin position; one set of tracks for each pan;

rollers associated with each pan to move therewith and engaging the set of tracks corresponding to the pan with which they are associated; an oscillatable bell crank; a link pivoted between the end of one arm of said crank and one pan, and a link pivoted between the end of the other arm of said crank and the other pan; and means for oscillating said bell crank between two positions to move said pans to and from said coating position, said last mentioned means including an oscillatable shaft to which said bell crank is fixed to be oscillated thereby; an oscillatable cam; a

lever fixed at one end to said shaft and including a follower on the other end engaging the working face of said cam; the rise of said cam be ng such as to oscillate said shaft a, sufllcient amount to move said pans between their two positions, and the contour of said cam being such as to give the pans a decelerating motion as they stop to counteract the sway generated in the liquid by the accelerated motion as the pans start to move; a reversible motor geared to said cam for driving the same; and means for automatically stopping said motor when the cam has been moved sufficiently to cause a coating pan to be moved to the coating position.

12. In a web coating apparatus the combination of a pair of coating pans adapted to contain a supply of coating solution and each movable between a coating position and a ready position; a pair of stationary inclined tracks each at opposite ends of one of said pans for guiding said pan between its ready position and the coating position, a second pair of stationary inclined tracks each at opposite ends of the other of said pans for guiding said pan between its two positions; rollers carried by opposite ends of each pan and engaging the pair of tracks corresponding t the pan by which they are carried to movably support the pans on said tracks; an

oscillatable shaft located vertically below said coating position; a pair of bell'cranks fixed to said shaft adJacent opposite ends thereof a link pivoted between the end of one arm of said cranks and one pan, and a link pivoted between the end of the other arm of said crank and the other pan, whereby said pans are caused to be moved along said tracks by an oscillation of said shaft between their ready and the coating position; the design of said levers, links, tracks and rollers being such that there is a balance of forces, due to the weight of the pans and all working parts, when expressed as a resultant torque on said shaft, at all times when the parts are moving; and means for oscillating said shaft to move said pans between their two positions of rest.

13. A coating apparatus according to claim 1 including two sets of inclined tracks for guiding the pans between their ready position and the coating position; one set of tracks for each pan; rollers associated with each pan to move therewith and engaging the set of tracks corresponding to the pan with which they are associated; an oscillatable bell crank; a link pivoted between the end of one arm of said crank and one pan, and a link pivoted between the end of the other arm of said crank and the other pan; and means for oscillating said bell crank between two positions to move said pans to and from said coatlng position, including a shaft oscillatable between two limits and to which said bell crank is pinned; an oscillatable disk having a spiral cam groove in its face the rise of which is suincient to oscillate said shaft between its two limits of movement; a movable arm mounted on one end of said shaft and connected to said shaft to oscillate the same as the arm is moved; a roller on the end of said arm engaging said cam groove; and means for oscillating said disk to bring said roller to opposite ends of said cam groove.

14. A coating apparatus according to claim 1 including two sets of inclined tracks for guiding the pans between their ready position and the coating position; one set of tracks for each pan; rollers associated with each pan to move therewith and engaging the set of tracks corresponding to the pan with which they are associated; an oscillatable bell crank; a link pivoted between the end of one arm of said crank and one pan, and a link pivoted between the end of the other arm of said crank and the other pan; and means for oscillating said bell crank between two positions to move said pans to and from said coating position, including a shaft oscillatable between two limits and to which said bell crank is pinned; an oscillatable disk having a spiral cam groove in its face the rise of which is sufiicient to oscillate said shaft between its two limits of movement; a movable arm mounted on one end of said shaft and connected to said shaft to oscillate the same as the arm is moved, a roller on the end of said arm engaging said cam groove; and means for oscillating said disk to bring said roller to opposite ends of said cam groove, comprising a reversible electric motor geared to said disk to drive the same in opposite directions; a manual double-throw switch in the motor circuit for instlgating the drive in opposite directions; a pair of normally closed limit switches in the motor circuit, includin operating arms extending to a point adjacent the periphery of said disk; and an actuating plate mounted on said disk and adapted to engage alternate ones of said switch arms depending upon the direction of movement of said disk to stop the motor drive when one of the pans has been moved to the coating position.

15. In a web coating apparatus the combination of a supporting frame; a pair of coating pans adapted to contain a supply of coating solution; means for mounting sai ans on said frame so that each pan is movable between a coating position and a ready position; means for simultaneously moving said pans between their two positions in opposite relation, whereby one pan is moved to the coating position at the same time the other pan is moved from the coating position to its ready position; cooperating adjustable stop screws and abutments on said frame and coating pans to accurately position each of said pans in a definite coating position; said means including an oscillatable driving shaft; a linkage between said shaft and said pans causin said pans to be simultaneously shifted between their two positions by an oscillation of said shaft; a driving cam; a driving linkage between said cam and shaft whereby the rise of said cam determines the degree of movement of said shaft; one of said linkages including a resilient coupling which will give only when said cooperating stop screws and lugs on said frame and pans engage, whereby said pans are definitely located and resiliently held in the coating position by said cooperating stop screws and lugs and all back lash and play is eliminated from said driving connection and linkage while a pan is in the coating position.

16. An apparatus according to claim 15 in which said resilient coupling includes a spring connecting a driven and driving part of said linkages and being of such gauge as to act as a rigid power transmitting member so long as the pans are free to move and adapted to flex when the cooperating stop screws and lugs come into engagement.

LEON P. MOREY.

REFERENCES CITED UNITED STATES PATENTS Name Date Number Roby May 10, 1927

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