US3043711A - Method and apparatus for the deposition of viscous liquid materials - Google Patents

Description

July 10, 1962 E. s. L. BEALE 3,043,711

METHOD AND APPARATUS FOR THE DEPOSITION OF vIscous LIQUID MATERIALS Filed Oct. 17, 1957 5 Sheets-Sheet 1 INVENTOR WSLM ATTORNEY July 10, 1962 E. s. BEALE 3,043,711

METHOD AND APPARATUS FOR THE DEPOSITION OF VISCOUS LIQUID MATERIALS Filed Oct. 17, 1952 5 Sheets-Sheet 2 Fla I/NVENTOR ATTDRNEY July 10, 1962 E. s. L. BEALE 3,043,711

METHOD AND APPARATUS FOR THE DEPOSITION OF vlscous LIQUID MATERIALS Filed Oct. 17,. 1957 s Sheets-Sheet 3 9 Lo Q '9 kn LO 1 U) a 2 (N o u 6; m

m I 3 w -3 Ln E k L 9 -0 Q L53 D Q o/vooas al d SFHO/V/ $5H9N/ INVENTOR fiw MW A TTORIVEY The present invention is concerned with improvements in and relating to apparatus for the deposition of thin layers of paints, inks and other viscous liquid materials in accurately defined areas on surfaces, the apparatus being of the kind comprising a matrix having a shallow cavity or a number of shallow cavities formed in its operative face for the reception of the material to be deposited on the said surface in patches or areas defined by the boundaries of the cavities in the matrix, which cavities are closed by the application of the surface intended to receive the deposited material against the said operative face of the matrix, conduits leading through the matrix to the cavities for the introduction thereto of the material to be deposited, and means being provided for controlling relative movement between the matrix and the surface intended to receive the deposit.

The materials to be deposited by utilization of such apparatus are liquids which remain in the accurately defined areas in which they have been deposited when the matrix and the surface are separated. For example, such apparatus has been used for the deposition of paint on sheets of paper or paper board to form what are known as colour cards.

In the liquid state ready for such deposition, paints for example, may have viscosities of between 25 and 1000 centipoises and when the matrix and the surface are separated after the deposition step, some of the viscous liquid material is drawn into one or a number of filaments or strings extending between the matrix and the surface, the cross-section of the string or strings becoming progressively more attenuated under the action of surface tension forces as the separation of the matrix and the surface is effected, and until the string or strings break. The breakage of the string or strings is influenced by the currents of air that enter between the matrix and the surface as they are separated.

With the apparatus of the above mentioned kind as hitherto used, separation of the surface bearing the deposited material from the matrix has been by a single continuous movement followed by a pause in the fully separated position with a view to enabling any remaining strings to break and the liquid to fall Within the boundary of the required area before the sheet bearing the deposit is removed from beneath the matrix. Difficulties have been encountered in the operation of the known machines due to the occurrence of splashing of the liquid material upon separation, with consequent blemishes on the finished sheets outside the required deposit areas.

The splashing has been found to be of two main kinds, one kind, termed for convenience, edge splashing, being caused by the breakage of some strings of large cross section at or near the edge of an area and forming pronounced blemishes in the form of streaks extending over the surface outside the desired deposit area. The other kind of splashing termed for convenience cannon ball splashing, is due to the formation during breakage of some of the strings of relatively large cross-section of separated droplets of material between two broken ends, such separated droplets being liable to be blown by the above mentioned air currents and deflected to such an extent that they land outside the desired area. Such deflected droplets cause either undesirable marks, or they may land on another adjacent areaand, in the latter case.

atent when for example the apparatus is being used for the production of colour cards in which each area carries a different colour, the droplet may adversely attect the colour of the area on which it lands.

It is possible with apparatus of the kind specified to largely avoid both kinds of splashing described above by utilising a very low speed of separation of the matrix and the surface but this would entail a great loss of time and such serious reduction in the rate of production of the colour cards or other articles as to render the method uneconomic.

It is an object of the present invention to provide an improved form of apparatus of the kind indicated above with which the occurrence of both of the above described kinds of splashing is avoided or reduced, whilst the period of time occupied in elfecting the total separation of the surface bearing the deposited liquid from the matrix is kept small.

According to the present invention an apparatus of the kind indicated above is provided having means for controlling relative movement between the matrix and the surface on which the deposit is made, so that after deposition the separation of the said surface from the matrix takes place in an initial phase of small predetermined extent at high speed of separation, the viscous liquid material drawn out between the matrix and the surface in that phase being predominantly in the form of numerous strings of small cross-section, the initial phase being follower by a second phase of low or nil speed of separation allowing time for breakage of some and usually most of said small cross-section strings and further followed by a third phase with a speed of separation higher than that of the second phase and of an extent which is greater than that of the first phase.

The said third phase may itself comprise a relatively short first part with an accelerating speed of separation followed by a second longer part with a decelerating speed of separation and in some cases a part of substantially constant speed may be provided between the said accelerating and decelerating parts of the third phase.

An example of an apparatus for the production of colour cards and making use of the present invention is illustrated in the accompanying drawings in which:

FIG. 1 is a view in side elevation showing a complete machine,

FiG. 2 is an underside view of a matrix,

FIG. 3 is a sectional view of the matrix taken on the lin-ellI--lll of FIG. 2, and

FIGS. 4 and 5 are two graphs representative of one cycle of separation movement typical of the present invention.

Referring to FIG. 1 of the drawings the apparatus comprises ahollow base 1 on which is mounted a frame structure comprising a rectangular base frame 2, four fixed vertical corner posts 3 and an open top frame 4 fixedly connected with the upper ends of the posts 3.

To the underside of the top frame 4 is fixedly connected a matrix 5 of the known kind shown in FIGS. 2 and 3, consisting of a metal block having shallow cavities 6 formed in its operative under face, the cavities being bounded by ridges 7 of small height, of the order of a few thousandths of an inch, extending from the surface of the matrix. Holes 8 are provided in the matrix leading from the upper side thereof to the interiors of the cavities 6 and the upper ends of the holes are threaded for the connection of tubes 9.

A support 10 carried fixedly by a pair of arms 11 extending upwards from the top frame 4 support a plurality of plunger pumps 1'2 for the liquid to be deposited. The inlet of each pump is connected through a flexible tube 13 with one of a number of reservoirs 14 for paint or 3 other liquid to be deposited carried in a convenient location above the apparatus, and the delivery end of each pump is connected with one end of one of the tubes 9 leading to the holes 8 through the matrix. The tubes 9 are of metal or other substantially inextensible material.

On the rectangular base frame 2 and in the space within the four posts 3 of the frame structure and below the matrix is located a vertically disposed hydraulic press 15, the cylinder 16 of which is supported on the base frame 2. The vertical ram 17 of the press carries a platen 18 the upper surface of which is parallel with the operative face of the matrix 5, both usually being horizontal as shown, the platen 18 being raised and lowered by the rarn17 and being maintained horizontal by guides 19 movable on the vertical posts3.

The direction of movement of the ram 17 and platen 18 is determined by a double-acting valve comprising a cylindrical valve body 24] containing a valve stem or spool 21 carrying two spaced lands 22 and 23 capable of masking simultaneously, two ports 24 and 25 leading from the valve body to the spaces 26 and 27 in the press cylinder 16 on opposite sides of the ram piston 28.

The axial length of the lands 22 and 23 is only slightly I greater than the width of the ports 24 and so that only very small movements of the spool 21 are required to unmask the ports 24 and 25.

A supply conduit 29 leads from a source of oil under pressure such as an electrically driven pump (not shown) for delivering oil at constant pressure to the valve body 29 at a point between the lands 22 and 23 of the valve spool and return conduits 30 and 31 are provided at the two opposite ends of the valve body 20 for the return of oil to a receiver (not shown) supplying oil to the pump or other source of constant pressure.

When the valve spool 21 is moved downwards the lower port 25 is unmasked by the lower land 23 and the supply conduit 29 for pressure oil is placed in communication with the space 27 below the ram piston 28 of the hydraulic press. At the same time the port 24 is unmasked by the upper land 22 and the space 26 above the ram piston 28 of the hydraulic press placed in communication with the upper oil return conduit 30. Thus hydraulic pressure takes effect to lift the ram 17 and raise the platen 18 towards the matrix 5.

. By, raising the valve spool 21, the upper port 24 may be put into communication with the pressure oil supply conduit 29 to admit pressure into the space 26 above the ram piston 28 of the hydraulic press, whilst putting the lower port 25 into communication with the lower oil return conduit. 31, so that the ram piston 28 is moved downwards to lower the ram 17 and the platen 18.

The rate of movement ofthe platen 18 in either direction can be varied by varying the extent to which the respective pressure feed port 24 or 25 is unmasked by the land 22 or 23 and the movement of the platen 18 may be caused to cease at any time by moving the valve spool 21 into the position in which the two ports '24 and 25 are both masked by the lands 22 and 23.

In fixed bearings at one side of the machine is mounted a cam shaft 32 driven at constant speed by an electric motor (not shown) and on the cam shaft 32 is fixed a cam 33 for co-operation with a cam follower 34 on one end of a restorer lever 35 having a yoke 36 at its other end embracing and pivotally connected through trunnion bearings 37 with a collar 38 fixed on the ram 17 of the hydraulic press 15.

The upper end of the valve spool 21 of the above described double acting hydraulic control valve is pivotally connected at a point 39 intermediate the ends of the lever 35 and a compression spring 54 between the upper end of the valve body 20 and a collar on the valve spool 21 holds the cam follower 34 up to the cam 33.

The cam 33 controls the movements of the restorer lever 35 and valve spool 21 and therefore the direction and speed of movement of the ram -17 and platen 18.

The extent to which the ports 24 and 25 are uncovered by movements of the valve spool 21 and lands 22 and 23, though variable, is always relatively small so that the restorer lever 35 may be seen as pivoting about a virtually fixed pivot point 39 and the rate of movement of the ram 17 as a close replica of thatof the cam follower 34. Thus the rate of movement of the platen 18 is for all practical purpose proportional to that of the cam follower 34 as determined by the shape of the profile of cam 33 and its rate of rotation.

On the cam shaft 32 is fixed a second cam 48 for co-, operation with a cam follower 41 at the lower end of a push rod 42 arranged for vertical movement in a fixed guide 43, the cam follower 41 being urged against the cam by a compression spring 44 on the lower end of the push rod 42. I I

The upper end of the push rod 42 engages the underside of one end of a lever 45 rockable in a vertical plane guide pins 48 on the pump support 10.

Springs 49 are provided on the guide pins 48 to urge the plate 47 upwards into engagement with the end of the lever 45. I

It will readily be seen that the plate 47 is moved up and down in response to the rotation of the cam shaft 32. During downward movement the plate 47 makes engagement with the plungers of the pumps 12 so that liquid supplied to the pumps from the reservoirs 14 by way of the tubes 13 is delivered by way of the tubes 9 through the holes 8 in the matrix 5 to the respective cavities 6.

Means forming no part of the present invention are employed for feeding sheets or cards intended to receive the deposits of liquid, singly in succession into and out of the apparatus, such means being shown diagrammatically in FIG. 1 as comprising a lay board 50, endless feeder bands 51 adapted to be clutched at int rva-ls to the cam shaft 32 or a part driven in'synchronism with said cam shaft, to receive a sheet or card from the lay board 50 and 'draw it into a position of rest over the platen 18, and after the deposition ofthe liquid on the s eet or card to draw said sheet with the deposit thereon from above the platen 18, a further group of driven endless bands 52 for receiving the sheets or cards Withdrawn by the feeder bands 51 from'the apparatus and usually introducing them into a drying oven 53.

The operation is as follows:

Starting with pressure liquid being delivered to the supply conduit 29, the platen 18 in its lowered position, the constant speed cam shaft 32 being driven, the cam 33 at a point in its rotation in which, the valve spool 21 is held in a position in which the two ports 24, 25, leading to the hydraulic press 15 are fully masked by the lands 22 and 23 and the second cam 40 is in a position in which the pump operating plate 47 is fully raised, a sheet is transferred by the conveyors 51 from the lay board 50 to a position over the platen 18, after which the continued rotation of the cam 33 operates to depress the cam follower 34 and rock the restorer lever 35 about the pivot 37 on the ram 17 so that a small depression of the valve spool 21 takes place to cause the port 25 to be unmasked by the lower piston 23 to an extent permitting pressure oil to enter the lowerrspace 27 of the hydraulic cylinder to raise the ram piston 28, ram 17 and the platen 18, the port 24 being correspondingly unmasked by the upper valve land22 so that oil from the space 26 above the ram piston 28 is permitted to flow away through return conduit 30.

It will be appreciated that the pivot 37 of the lever 35 rises as the platen 18 rises but the part of the profile of the cam 33 responsible for the lifting movement of the platen is selected to ensure that valve spool 21 remains substantially unmoved so that the port 25 remains unmasked to fully raise the platen 18 and the sheet thereon into pressure engagement with the operative face of the matrix 5 to cover the cavities 6 therein.

Whilst such pressure engagement is maintained, the second cam 40 comes into operation to raise the push rod 42 and rock the lever 45 about its pivot 46 to lower the plate 47 and depress the plungers of the pumps 12 so that liquid is delivered through the tubes 9 and the holes 8 through the matrix 5 to the cavities 6 and deposited on the sheet on the platen in a number of areas accurately defined by the ridges 7 forming the borders of the cavities 6.

The cam 40 then permits-the return of the push rod 42 and rising of the plate 47 and plungers of the pumps 12 so that no further flow of liquid can take place in the delivery pipes 9 and the sheet with the deposit thereon is now ready to be parted from the matrix 5 by lowering the platen 18.

The downward movement of the platen 18 is controlled by a part of the cam 33 enabling upward movement of the cam follower 34 with pivoting of the restorer lever 35 under the urge of the compression spring 54, the valve spool 21 being permitted to rise to the extent necessary to cause the upper port 24 leading to the space 26 above the ram piston 28 in the hydraulic press 15 to be unmasked by the upper valve land '22 and p aced in communication with the pressure oil supply conduit 29, and the lower port 25 leading to the space 27 below the ram piston 28 in the hydraulic press 15 to be unmasked by the lower valve land 23 in the reverse sense to that previously considered and placed in communication with the oil return conduit 31. The rate of the downward or separation movement of the platen 18 is dependent upon the rate at which the hydraulic oil is permitted to enter the space 26 and emerge from the space and this is dependent upon the extent to which the ports 24 and 25 are unmasked by the Valve lands 22 and 23 and it will be seen that following a rise of given extent permitted to the follower 34 by the cam 35 the rate of downward movement of the platen 18 would gradually decrease due to the fact that downward movement of the platen 18 involves downward movement of tion in the second or pause phase may fall to nil, that is to say the valve lands 22 and 23 may be caused temporarily to mask the ports 24 and 25 completely so that no hydraulic oil is permitted to flow to or from the hydraulic press 15. During the pause phase a large proportion of the remaining small cross-section strings break without appreciable splashing, as a result of the eifect of surface tension forces.

The second or pause phase is followed by a third phase during which the matrix 5 and the platen 18 with the sheet thereon are separated to their full extent and at the end of which the platen 18 comes to rest in its lowered position. The separation during the third phase is of larger extent than that taking place in the initial phase and it takes place at a speed which is greater than that of the second phase and may in some cases be greater than that of the initial phase. During this third phase any remaining strings break and without the production of noticeable cannon-ball splashes since the air velocity between the separating parts during this phase is relatively low due to the large flow area now available for air flow between the matrix and the platen. The third separation phase in some cases consists of a relatively short part during which the speed of downward movement of the platen increases continuously with consequent rapid attenuation of any remaining strings of large cross-section, followed by a relatively long part during which the speed of separation decreases and the platen is brought to rest.

Again, the third phase may in some cases include a period of substantially constant velocity between the accelerating and decelerating parts of that phase.

With the need for the highest possible production rates in mind it is desirable thatthe extent of up and down movement of the platen be kept small and the time occupied by a complete cycle of platen movements be kept as short as possible subject to satisfactory separation of the sheet from the matrix with absence of splashing and it is found that by utilising a three phase parting movement between the matrix and platen as described above the valve spool 21, and would cease when either or both of the ports 24 and 25 are closed by the lands 22, 23.

It will thus been seen that by the-utilisation of a cam 33 of suitable profile the platen 18 may be caused to move downward at speeds which can vary between the maximum of which the hydraulic system is capable and zero.

In carrying out the present invention that part of the profile of the cam 33 which is responsible for the lowering movement of the platen 18 is selected to cause that lowering movement to, take place in three phases. The initial phase is a separation phase of small Predetermined extent and high speed which apart from occupying a minimum or near minimum of time results in the filaments or strings of the liquid material drawn out between the cavities 6 of the matrix '5 and the sheet on the platen 18 being numerous and of predominantly small cross-section.

' Some of these strings of small cross-section break during this initial separation phase and the falling portions rop wholly or for the main part within the required areas on the sheet and whilst some of such small strings "breaking during this initial phase may be deflected by the inflowing air, due to the short length and small crosssection of the strings, any consequent edge splashing which may occur is of little if any practical importance.

The above described initial phase of separation is followed by a second, pause phase during which the speed of downward movement of the platen 13 with the sheet bearing the deposit is low as compared with that of the first phase and with some materials the speed of separaeffective complete separation of the sheet with its deposit thereon from the matrix can be achieved with absence of splashing in a much shorter total separation time than with the continuous separation movement employed with hitherto known machines used for the production of colour cards.

FIGS. 4 and 5 are graphs having common abscissae in terms of time in seconds and ordinates, in FIG. 4 expressed in units of speed of separation movement of the platen and in FIG. 5 the extentof movement of the platen represented in inches, and showing one typical separation cycle of movement using paints or liquid of viscosities between and 300 centipoises.

In the first separation phase the platen moves downwards .12 of an inch (FIG. 5) in a period of .03 of a second reaching a maximum speed of 8.5 inches per second (FIG. 4), followed by a second phase in which the platen moves .12 of an inch (FIG. 5) in .085 of a second at a low and substantially constant velocity of 1.5 inches per second (FIG. 4), and a third phase in which the platen moves 1.11 inches (FIG.- 5) in a period of .25 of a second at a maximum velocity of 6 inches per. second (FIG. 4).

Utilising such a three phase movement in a total separation distance of 1.35 inches in a separation time of .365 of a second it has been found possible to obtain in the region of 3000 satisfactory depositions per hour.

-In the example shown it will be seen from FIG. 4 that the maximum velocity of separation movement attained in the first phase is higher than the maximum velocity reached in the third phase.

In the graph of FIG. 5 the third separation phase is shown as comprising a movement at substantially constant velocity between periods of acceleration and deceleration of which the former is shorter in duration than the latter.

I claim:

1. An apparatus for use in the deposition of thin layers of viscous liquids in, accurately defined areas on surfaces, comprising a matrix Withshallow cavities in its operative surface corresponding in shape with the said areas, a platen for holding the surface intended to receive the deposit in cavity-sealing engagement with the operative face of the matrix, conduits leading the viscous liquid from a supply source through the body of the matrix to the cavities in the operative face thereof while the surface to receive the deposit is in such sealing engagement with the matrix, mechanism for effecting relative movement between the matrix and the platen to enable a surface intended to receive the deposit and supported by the platen to be clamped between the matrix and the platen during deposition of the liquid and thereafter to separate the surface supported on the platen and having the deposit thereon from the matrix, and means controlling the mechanism for effecting relative movement between the matrix and the platen with a non-uniform time cycle such that a single separation of the surface with the deposit thereon from the matr'nr takes place in an initial phase of pre-determined extent at high speed followed by a second phase of low speed and further followed by a third phase with a speed higher than that of the second phase and of an extent of movement which is greater than that of the first phase.

2. An apparatus for depositing a thin layer of viscous liquid coating composition in accurately vdefined areas on a surface comprising a cavitated matrix which may be engaged with said surface to deposit said composition the surface and matrix, then at a second speed lower than said first speed wherein a lesser part of the liquid composition bridges the separation gap, next at a third speed greater than said second speed to produce a still further separation movement to an extent greater than said first separation and finally to stop such movement.

' 3. An apparatus as claimed in claim 2 wherein said control means causes said motion means to accelerate the separation movementfrom the second to the third speed at a higher rate than the rate of deceleration to stop said movement.

4. An apparatus as claimed in claim 2 comprising a fixed matrix and a vertically movable platen, said motion means including a double-acting hydraulic press for raising and lowering the platen, and said control means comprises a movable control valve for controlling the rate of entry of hydraulic fluid into the hydraulic press and a three lobe cam controlling the movement of said movable control valve during the downward separation movement of the platen.

5. An apparatus as claimed in claim 2 wherein said 7 control means controls said motion means so that the said first speed is greater than said third speed.

6. An apparatus as claimed in claim 2 wherein said control means operates to provide during said separation movement at the third speed, a period of constant move- 8 ment between acceleration from the second speed and deceleration to stop such movement.

7. An apparatus as claimed in claim 2 wherein said control means controls said motion means so that the extent of separation movementv at said third speed is greater than the extent of separation movement at said first speed.

8. A method of producing accurately defined coated areas on a surface by deposition of a thin layer of viscous liquid coating composition on the surface which comprises bringing a cavitated matrix having shallow cavities formed in its operative face into sealing engagement with said surface, delivering liquid coating composition to said cavities through conduits leading through the matrix causing the coating composition to be applied to said surface in areas defined by said cavities, then separating said matrix and surface by a predetermined extent at a first speed to draw out filaments of said liquid composition to bridge the gap formed between said matrix and surface by said separation, continuing such separation of matrix and surface at a second speed lower than said first speed during which at least some of Said filaments break without splashing and then still further separating said matrix and surface at a third speed greater than said second speed to an extent insuring breakage of all said filaments.

9. The method of claim 8 in which the separation at the third speed includes an initial accelerating movement from the second speed and a final decelerating movement at the end of movement at the third speed, the decelerating period being longer than the period of acceleration.

10. A method of producing accurately defined coated areas on a surface by deposition of a thin layer of viscous liquid coating composition on the surface which comprises bringing a cavitated matrix having shallow cavities formed in its operative face into sealing engagement with said surface, delivering liquid coating composition to said cavities through conduits leading through the matrix causing the coating composition to be applied to said surface in areas defined by said cavities, then separating said matrix and surface by 'a predetermined extent in a direction normal to said surface at a first speed to form a gap between the matrix and surface, continuing such separation of matrix and surface at a second speed lower than said first speed, next still further separating said matrix and surface at a third speed greater than said second speed to widen said gap, thereafter stopping the relative movement between matrix and surface and finally withdrawing said sheet from the vicinity of the matrix in a direction parallel to said surface.

References Cited in the file of this patent UNITED STATES PATENTS 1,122,616 Kuebler et a1. Dec. 29, 1914 2,032,028 Rees Feb. 25, 1936 2,302,096 Battey Nov. 17, 1942 2,329,288 Miller Sept. 14, 1943 2,656,570 Harmon et a1. Oct. 27, 1953 2,697,253 K-ruft Dec. 21, 1954 2,794,415 Hillman June 4, 1957 FOREIGN PATENTS 494,508 Belgium Mar. 31, 1950 813,382 Great Britain May 13, 195.9

Claims (1)

1. 2. AN APPARATUS FOR DEPOSITING A THIN LAYER OF VISCOUS LIQUID COATING COMPOSITION IN ACCURATELY DEFINED AREAS ON A SURFACE COMPRISING A CAVITATED MATRIX WHICH MAY BE ENGAGED WITH SAID SURFACE TO DEPOSITE SAID COMPOSITION THEREON, MOTION MEANS FOR RELATIVELY MOVING THE MATRIX AND SURFACE AWAY FROM EACH OTHER TO CAUSE SEPARATION THEREBETWEEN AND CONTROL MEANS AUTOMATICALLY OPERATIVE DURING SAID SEPARATION FOR CONTROLLING THE MOVEMENT OF SAID MOTION MEANS TO PRODUCE SUCH MOVEMENT SUCCESSIVELY AT A FIRST SPEED AND TO A FIRST EXTENT WHEREIN AT LEAST PART OF THE LIQUID COMPOSITION BRIDGES THE GAP BETWEEN THE SURFACE AND MATRAIX, THEN AT A SECOND SPEED LOWER THAN SAID FIRST SPEED WHEREIN A LESSER PART OF THE LIQUID COMPOSITION BRIDGES THE SEPARATION GAP, NEXT AT A THIRD SPEED GREATER THAN SAID SECOND SPEED TO PRODUCE A STILL FURTHER SEPARATION MOVEMENT TO AN EXTENT GREATER THAN SAID FIRST SEPARATION AND FINALLY AT STOP SUCH MOVEMENT.

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