US2017510A

US2017510A - Powdering machine

Info

Publication number: US2017510A
Application number: US513364A
Authority: US
Inventors: Frank T Powers
Original assignee: Individual
Current assignee: Individual
Priority date: 1931-02-04
Filing date: 1931-02-04
Publication date: 1935-10-15
Anticipated expiration: 1952-10-15

Description

Oct. 15, 1935. F. T. POWERS PowDERING MACHINE Filed Feb. 4, 1951 4 Sheets-Sheet 1 ...Uw WSJ... K d+ Oct. l5, 1935. F. T. POWERS POWDERING MACHINE Filed Feb. 4, 1931 4 Sheets-Sheet v 2 INVENTOR 4 T-w" n Oct. l5, 1935. F. T. POWERS POWDERING MACHINE Filed Feb. 4, 1951 4 Sheets-Sheet I5 1 INVENTOR GK c 8*; i YW oct. 15, 1935.

F. T. POWERS POWDERING MACHINE Filed Feb. 4, 1951 4 Sheets-Sheet 4 Patented Oct. 15, 1935 UNITED STATES 'PATENT vor-'Flclz Frank T. Powers, .Douglastom N. Y.

Application February 4, 1931, Serial No. 513,364

29 Claims.

lectively as powdering, in which a powdered resist is applied to the partially etched surface of the plate.

Among the objects of my invention are, to provide a process and apparatus for applying powdered resist in a better and more consistently uniform manner than can be done by hand, and to decrease the time required to apply powdered resist to a series of plates. Other objects and advantages will be set forth hereinafter and in part will be obvious herefrom, or may be learned by practice with the invention, these objects being accomplished by means of the instrumentalities and combinations pointed out in the following description and in the appended claims.

In the present state of the art of making printing plates by what are commonly called the half tone process andthe line cut process, it is the custom to produce, by photographic means, an image of the design to be etched upon the especially prepared and sensitized surface of a plate of metal, usually of copper or zinc. Various methods are commonly used to produce the image on the plate, such, for example, as the cold enamel process, or what is commonly called an ink top may be used. By whatever process used, there is produced upon the surface of the metal plate an image of the design to be etched, consFsting of a layer of etchant resisting material on those port-ions of the surface of the plate which are to be printing areas in the finished printing plate, and leaving uncovered and unprotected from the action of the etchant those portions of the surface of the plate which are not to be printing areas in the finished printing plate.

The plate so prepared, or equivalently prepared, is coated'` on its reverse side with suitable etchant resist, such for example as asphalt enamel, and is then exposed to the action of an etchant in an etching machine.

The first exposure to the etchant is called the rst bite and the amount of etching done or the depth to which the etching is allowed to progress is very slight, in the order of magnitude of one to two thousandths of an inch.

'I'he next step is to apply a powdered resist or etchant resisting material to the partially etched surface of the plate to protect the sides or edges, or what are commonly called the shoulders of the etched figures on the plate, to prevent undercutting and to permit of carrying on the etching process to a depth which will give satisfactory printing quality to the plate. This step is called powdering and it is to this step of the process that I apply my new process and apparatus.

It is necessary to apply the powder to the surface of the plate "four ways", i..e., in four directions, in order that the shoulders on all sides of all portions of the image will be protected. The procedure comm-only used heretofore for applying the powder is to scoop up on one edge of the plate a quantity of loose powder, and by tilting the plate up to a steep angle, to permit the loose powder to iiow or slide across the entire surface of the plate. 'I'he next step is to brush the powder by means of a wide iiat brush, usually of camels hair, and pack it against the side of the shoulders, always brushing in one direction, and continuing the brushing until, in the opinion of' the operator, the process is complete and the powder properly packed against the shoulders of the design.

The next step is to heat the plate by suitable means, such, for example, as a gas stove, to a carefully determined and uniform temperature, such that the powder is partially melted, or incipiently fused against the shoulders, and so becomes rmly attached to the metal and capable of protecting the shoulders against further attack by the etchant when subjected thereto.4 'I'his heating process is commonly called burning in". The plate is then cooled'by suitable means, such as the application of water, is then dried, and again subjected to a similar application of powder, as above described; but starting the powder and the brushing at one of the other three sides of the plate. After proper brushing, burning in, cooling and drying, the same cycle of processes is repeated until the design on the plate has been powdered from each of the four directions, top, bottom and each side.

It will be noted that this powdering operation involves numerous operations, each of which must be repeated four times. Some of these operations, particularly those oi.' brushing the powder up against the shoulders of the design and the burning-in of the resist, require experience and skill and the exercise of judgment basedthereon. Variations in the handling of the brush, the pressure exerted upon the plate, the position oi' the brush, the speed of brushing, the number of brushings,-all exert an influence upon the result and all are subject to the judgment or skill, and also to the carelessness of ignorance of the operator. The burning-in process is also one requiring care and experience to perform properly. Overburning or underburning or uneven burning, resultI in poor quality of product, if not complete failure.

It is very common in the hand operated process of powdering and burning-in for the plate to Warp and bend as a result of the heating, cooling and handling. The rapid applicationof heat in the step of fusing the powder tends to warp or curve the plate. The handling of the plate before, during and after heating by means of pliers, by which the edge of the plate is gripped and the plate lifted and conveyed by hand, often bends the plate.

The sudden cooling of the heated platebyv the application of water also has a warping or curling effect on the plate, sometimes resulting in considerable distortion.

The sum of the results of these bending, curling and deforming influences is often cumulative and makes it necessary for the operator to straighten the plate repeatedly during the process of powdering. This straightening is commonly accomplished by forcibly slapping the plate down on a flat surface, or bending it over an edge.

In my new powdering machine I provide means for restraining the plate while cooling to prevent warping, and'to take out any distortion or warping which may have occurred during the heating process.

To eliminate this human element, with its attendent lack of uniformity and imperfection of result, and to increase the speed of production by enabling a number of plates to be simultaneously subjected to the cycle of steps of the powdering process automatically and mechanically, and with exactly similar treatment, as to brushing, burning-in, cooling and drying, I have invented the process and an apparatus hereinafter described and illustrated in the accompanying drawings.

Of the drawings, Fig. 1 is a side elevation of the apparatus looking at side A-A of Fig. 2.

Fig. 2 is a plan view of the apparatus.

Fig. 3 is a section through the powder hopper on the line B-B of Fig. l.

Fig. 4 is a partial section of the powder distributor and brushes on the line C-C of Fig. 2.

Fig. 5 is a partial section of the heating chamber viewed on the line D-D of Fig. 2.

Fig. 6 is a detail of the cooling unit viewed along the line E E of Fig. 2.

Fig. '1 is another detail of the cooling unit and indicator viewed on the line F--F in Fig. 2.

Fig. 8 is a detail of one of the cooling unit straightening rollers.

Fig. 9 is a detail of the indicator.

Fig. 10 is an end elevation of the apparatus looking at the end G-G of Fig. 2.

Figs. 11, l2 and 13 are details of transfer bar fingers.

Fig. 14 is a plan view and Fig. l5 is an elevation of the transfer arm mechanism.

Figs. 16 and 1'7 are details of the transfer arm.

Fig.- 18 is a detail of one of the pusher bars.

In Fig. 2 a plurality of bars, I, spaced apart, form collectively a support for the plate to be powdered. The endless link chains, 2, 2, engage

sprockets

3, 3, and also sprockets 3a, (Fig. 1) which are in turn driven by means of a spur gear, 4, meshing with spur gear 4a, mounted on the same shaft with sprocket wheel 1, which is driven by chain 6 from sprocket 8, mounted on shaft 51, on which is also mounted worm gear 58 driven by worm 59, mounted on common shaft with sprocket 59a, which in turn is driven by chain 1I, which is carried on sprocket 12 mounted on main drive shaft 5. The shaft, 5, receives powerl from a motor, not shown, through a belt, not shown, cooperating with pulley, 11.

Attached to the chains, 2, 2, by means of suitable attachment links, are cross bars, I2, spaced at equal distances apart. These cross bars are provided with lugs, I3, projecting'both below the lower and above the upper surfaces of the bars, as shown in detail in Fig. 18. These lugs eliminate the possibility of a warped or curved plate, getting over the top of the cross bars or under them in the operation of the machine.

A powder hopper, I4, (see also Figs. 3 and 4) is supported above the bars, I, in which is suitably mounted an agitator brush, I5, provided with a worm gear mechanism, I 6, whereby the brush is slowly rotated when power is transmitted through the gear mechanism by means of the belt, Ilia, cooperating with the pulley, I1, on the jack shaft, I 8, driven by the belt, I9, from the pulley, 20, on the main driving shaft, 5.

In the bottom of the powder hopper is provided a slot, 20a, of a. suitable width, such that as the brush, I5, revolves, powder will be ejected through the slot.

Under the grid bars, I, is supported a tray, 2i, to catch such powder as may fall between the grid bars. Within the tray, 2I, a series of rakes,

`22, are reciprocated by means of links, 23, 23,

one on either side, connected to the cross bar, 24, and actuated by the crank, 25, attached to the shaft, 26. By means of the pivoted rails, 21, 21, (see Fig. 4) cooperating with the pins, 28, 28, attached to the rakes, the rakes are lifted off the bottom of the tray, 2|, as they travel in the direction away from the hopper, I4, by reason of the pins, 28, travelling up on the pivoted rails, 21; and said rakes slide under the pivoted rails. 21, on the bottom of said tray when travelling in the opposite direction toward the powder hopper. By reason of this action of the rakes any powder in the trays is intermittently moved toward and pushed into the trough, 29, in which is a chain conveyor, 30, having flights, 3|, attached at suitable intervals. At the ends of the trough, 29, are rectangular vertical ducts, 32, 32, communicating with a horizontal conveyor trough, 33, located above .the hopper, I4, and provided in its bottom with suitable diagonal ried along the trough by the conveyor flights is slot opening, 34, by means of which powder cardistributed to the hopper below. At the upper and lower ends of the vertical ducts, 32, are provided suitably mounted sprockets, 35, 35a, which engage the conveyor chain, 30, and guide it in its course. One of these sprockets, 35a, serves as the driving sprocket, being driven by a suitable combination of gears, 36, belt, 31, and pulley, 38, upon the main drive shaft, 5.

Above the bars, I, carried in suitably mounted adjustable bearings, 39, 39, (see Fig. 4) are rotary brushes, 40, 40, provided with sprocket wheels, 4I, 4 I, by means of which they may be driven through the belt, 42, from the pulley, 43, mounted on the main shaft, 5.

The brushes, 4D, are so mounted in bearings that theyare adjustable as to their height by means of the adjusting screws, 44, shown in Figs. 2 and 4.

A second set of grid bars, 45, spaced apart from each other and also spaced apart at 46, (see Fig.

1) from the grid bars, I, are suitably supported over a plurality of gas burners, 41, 41, supplied with gas from'a common header, 48, provided with a shut off valve and a pressure regulating valve, both of well known types and not shown in the drawings. Above the grid bars, 45, at a suitable distance, is a heat absorbing and reflecting plate, 5I, backed with a layer, 52, of insulating material, such as asbestos, or other suitable material. A second pair of link chains, 53, 53, similar to chains, 2, and provided with cross bars, 54, 54, similar to cross bars, I2, I2, having lugs, 55, 55, similar to lugs, I3, engage with sprocket wheels. 56, 56, mounted on shafts, 51, 51a, one of which shafts, 51a, is driven by means of the Worm gear, 58, which engages worm, 59, which in turn is driven by sprocket which engages chain, 1 I, which in turn is driven by sprocket, 12, on main drive shaft, 5.

At the ends of grid bars, 45, is suitably mounted a metal table, 60,v having a smooth top surface. Over this table is mounted a rotatable transfer arm, 6I, carried by a vertical shaft, 62, (see also Figs. 14 and 15) operating in bearings, 63, 63, and oscillated through an arc of approximately 90 deg. by means of a lever arm, 64,l connected pivotally to a link, 65, which is pivotally con-- nected at its opposite end to a lever arm, 66, carried on a vertical shaft, 61, which is rotated by means of the worm gear, 68, engaging a worm, 69, which is driven by means of the sprocket Wheel, 10, cooperating with chain, 1|, which engages sprocket wheel, 12, on main driving shaft, 5.

On vertical shaft, 62, the rollers, 13, engage the two wedge shaped cams, 14, 14, which are given a reciprocating motion by means of the link bar. 15, pivotally connected to crank pin, 16, attached to worm gear, 68, driven as described above. The relative positions of the lever arm, 66 and the crank pin, 16, on the shaft, 61, are such that when transfer arm, 6|, is in its extreme position at a in Fig. 2, the cam, 14, does not engage the rollers, 13, and, therefore, the shaft, 62, together with the transfer arm 6I, is in its lowest position and remains so while the movement of the lever arm, 64, carries the transfer arm'from the position a around to position b in Fig. 2. But said cam, 14, will engage rollers, 13, and so lift shaft, 62, together with transfer arm, 6|, after transfer arm reaches position b and maintain it in the raised position while it is returning to position a. On the side of the transfer arm, 6I, are loosely mounted one or more plates, 49 (see Figs. 16 and 17) which rest upon and slide over the top of the table, 60, (as shown in Fig. 17) while the transfer arm is travelling from position a to position b, and which will be raised up off the table (as shown in Fig. 16) While the transfer arm is travelling from position b to position a.

Attached to the top of table 60 is a curved guide, 60a., which guides the plate while in motion from position a to position b.

A third set of grid bars, 11, is located a suitable distance beneath the under side of table, 60, and a third pair of link chains, 18, 18, with cross bars, 19, 19, engage sprocket wheels, 8|, 8|, carried on suitably mounted shafts, 82, one of which is driven by sprocket wheel, 83, driven by chain, 84, from sprocket wheel, 85. sprocket wheel, 85, is mounted, extends across the machine to the opposite side and has mounted on it a sprocket wheel, 1, which engages chain, 6, and is driven as described above by sprocket wheel, 8, worm gear, 58, worm 59, a sprocket The shaft, a, upon which wheel, 59a, chain 1| and sprocket wheel 12, which is mounted on the main drive shaft, 5.

Under the grid bars, 11, are located, suitably mounted, a plurality of cooling rollers, 96, 86,

which are shown more in detail in Figs. 6 and '1. 5

These rollers are constructed of separate sections, 81, 81, mounted spaced apart on a common shaft, 88, the sections being of a width somewhat less than the distance between the grid bars, 11, and being covered with a layer, 89, of soft, 10 resilient water absorbent material, such, for example, as felt or a heavy carpet. These rollers are so mounted with respect to the grid bars, 11, that the tops of the rollers are slightly above the tops of the grid bars. On one end of the shafts of 15 each of the rollers are mounted two chain sprocket wheels, 90, 90, and each successive roller is driven from the sprocket wheel on the shaft of the next adjoining roller, while the final or end roller is driven by the chain, 92a, engaging 20 sprocket wheel, 92, mounted on shaft, 51, which also carries sprocket wheel, 85, the driving of which is described above. y

Underneath the cooling rollers, 96 (see Fig. 6) is a water tray, 93, provided with means for being 25 supplied with water from any suitable source,

such as the pipe, 94, and provided with an overflow,y 95. to insure a constant level of water in the tray, such that the lower portion of cooling Lrollers will be continually submerged. Roller 96 30 19, to pass under them without coming into con- 40' tact therewith, as shown in Fig. 8.

The shafts, 9, of these pressure rollers are loosely mounted on bearings so that they are free to move up and down as the plates pass under them, and the weight of the rollers is.borne by the plate. 45 'I'hese pressure rollers perform the multiple functions of straightening the plates, keeping them from warping as they are cooled, and of holding them down in intimate contact with the wet cooling rollers, 86. I 50 On the shafts, 9, of the pressure rollers, 91, are rigidly attached sprockets, I0, the teeth of which engage the link chains, 18, by means of which the rollers are rotated in synchronism with the cross bars. 55 At the end of the grid bars, 11, but spaced apart therefrom to permit the cross bars, 19, 19, to pass between, is a transfer table, 98, having a top of smooth metal. A pusher arm, 99, is rotatably mounted in a cross head, |00, slidably 60 mounted on guide rods, I 0 I, IUI. The pusher arm is provided with fingers, |02, |02, having a limited rotary motion about the pusher arm, 99, as shown more in detail in Figs. 10, 11, 12 and 13.

The pusher arm, 99, is rotatably mounted in 65 crosshead, |00, but is provided with a wide keyway, |03', and a narrow key, |04, so arranged that the arc of rotation of the pusher arm in the crosshead is limited to about l0 deg. The pivotal connection, I 04a, between the pusher arm, 99, and 70 the connecting link, III, is above the centre of rotation of the pusher arm; so that when the connecting link pushes the crosshead in one direction, it rotates the pusher arm through an are of about l0 deg. only, and when the connecting 75' ,of levers and connecting rods actuated by the cam disc, |05, in the race, |06, of which a roller, |01., travels and thereby actuateslever, |08, to which it is attached. Lever |08 in turn actuates .lever |09 through connecting link, ||0, and lever |09 actuates the crosshead, |00, through connecting link,

The cam disc, |05, is attached to shaft, ||2, which is driven through bevel gears, H8, shaft |44, worm gear ||5, worm ||6, shaft ||1, sprocket wheel 8, and chain H9, from the sprocket |20, mounted on main drive shaft 5.

at its lower end, and a pall, |25, at its upper end, provided with a spring, |26, which insures contact between the pall and a ratchet wheel, |21. A contact pointer, |28, is attached through a central shaft to the ratchet wheel and rotates with it. An insulated contact pin, |29, is suitably located and wired to a source of electrical power and also toa suitable alarm device, such as a bell or a buzzer or an electric horn, all `of common and well known types and not shown in the drawings or further explained. l The wire, |30, shows one point of attachmentof the electric circuit, the other being grounded at any convenient point on the frame of the apparatus. The number of notches-on the rim of the ratchet wheel, |21, is such that while a plate being powdered travels four times through the machine, the ratchet wheel will make one4 revolution.

It will be'obvious toone skilled in the art that other combinations of parts and other arrangements of the same or equivalent parts may be utilized to carry out the invention without departing from its spirit. The embodiment shown and described is a preferred arrangement, and one which has been found satisfactory; but I do not wish to be understood as limiting my invention or claims to this particular arrangement or design.

Having described one form of apparatus embodying my invention, I- will now describe its operation. g

The plates to be powdered are first prepared by usual and well known methods of sensitizing and printing, and are given their first bite in an etching machine as described above, washed to remove the residual etchant and dried. 'Ihe powdering machine is prepared for starting by turning on and igniting thev gas supply of the heating burners, 41, ,and starting the motor which drives the entire mechanism. After sufficient time has elapsed to permit the heating burners to heat up the section ofthe apparatus in which the burning-in takesplace, including the heat reecting baffle, 5|, -to the proper working temperature, the contact pointer, |28, is set to starting position pointing vertically upward, the plates to be etched are placed face up and one at a time upon the grid bars, 11, at the point, XI. As each plate is moved along by the pusher fingers on the cross bars, 19. in the direction indicated by the arrow,

, tion of rotation indicated by the arrows.

link pulls the crosshead in the other direction,

another plate is put in position to be pushed along the grid bars in the same direction by the pusher fingers of the next succeeding cross bar, and this addition of successive plates is repeated until all plates have been placed in position, or until I all spaces in the machine are occupied by plates being powdered.

As the plates, one after another, are pushed along the grid bars, 11, they are moved over and on to the transfer table, 88, and are left supi0 ported thereon when the pusher fingers on the cross bars, 19, are moved out of contact with the plate by reason of the cross bars being carried by the chains, 18, around the sprocket wheels, 8|. 'Ihe pusher arm, 99, which travels with a timed i5 reciprocating motion across the transfer table, 98, in the direction indicated by the arrow, next pushes each successive plate to be etched from the position in which it was left by the cross arms, 19, to a position just beyond the transfer 20 table, 98, upon the grid bars, which have rounded tops to prevent the corners of the moving plate catching against the tops of the grid bars.. As the plates come to rest in their new position on the grid bars, the cross bars, I2, 25

. bars under the outlet or discharge of the powder hopper, |4, where a supply of powder is deposited upon the upper surfaces of the plates by the 30 motion of the agitator brush, I5, within-the hopper. The plate continues to move at a uniform rate in the same direction and passes successively under a plurality of rotating brushes, 40, which revolve at a constant speed in the direc- 35 The first of these brushes removes the surplus of powder from the surface of the plates and deposits a portion of the remaining powder against the shoulders of the partially etched designs. 40 'I'he succeeding brushes clean the powder from the smooth surfaces oi' the plates and pack it up with the proper degree of compactness against the shoulders. When the plates have passed under the last brush they have received just the proper amount of brushing applied with the `proper pressure and at the proper speed to produce the best result. The plates continue to move along -the top of the grid bars, beyond their end and on to the top of the second set of grid bars, 45, where they are left in a stationary position, as the cross bars, I2, are carried by the chains, 2, around the sprocket, 3a. The plates are then moved forward by the cross bars, 54, carried by chains, 53, along the top of the grid bars, 45, over the heater burners, 41, and under the heated surface of the baille, 5|, and become heated to the required temperature to partially melt or incipiently fuse the powder lying against the shoulders of the design on the surface of the partly etched plates.

After the plates have passed through the heating section over the heating burners, they are pushed beyond the end of the grid bars, 45, on

the transfer table, 60, where they are left in a therefore, receive their brushing in a new position at a right angle to their position at its last previous brushing. As each plate is rotated 90 degrees each time it is moved from position X4 to position X5, it is obvious that when each plate has passed four times through the machine uninterruptedly, it will have been powdered four ways. In their passage over the top of the table, 60, the plates are guided by the curved guide bar, 80a, into their new position on grid bars, Tl. As the plates are pushed off the edge of the table, 6U, they drop on grid bars, 11, and come into contact with the wet rotating cooling rollers, 86, and at once begin to be cooled.

The pusher bars, 19, next move the plates forward in the direction of the arrowr from position X5, under the table, 60, and over a plurality of cooling rollers, 86, which are kept wet by reason of their dipping into the water in tray 93. During this passage over the wet rollers the plates are held down into contact with them by the pressure rollers, 91. These pressure rollers perform three important functions. They hold down the plate in contactwith the wet cooling rollers and they also straighten the plate by removing any curvature or warping existing in the plate as the result of heating and they prevent any warping occurring in the process of cooling. After the plates have passed the last wet roller, there may be drops of water on the undersurface, but as they pass the drying roller, 96, these drops are absorbed. The plates have now made a circuit of the machine and been powdered, brushed, heated, turned 90 degrees, and cooled and straightened, and they are now ready for a repetition of these steps three times more before being completely powdered four ways and ready for the next etching. 'I'he contact pointer, |28, on ratchet wheel, |21, has made one quarter of a revolution and indicates to the operator by its position that the rst plate placed on the machine has completed one circuit. The plates are permitted to continue through the various steps until four complete circuits have been made, when the contact pointer, |28, will make contact with the insulated contact pin, |29, and the alarm will announce to the operator the completion of the operation.

I am aware that machines have been made to perform one or more of the functions or operations of my new machine. Some of these machines have been designed to perform several of these operations in succession on one plate only,

the plate travelling through each of the instrumentalities in succession. Reversing the travel, the plate then returns through the same route to the starting point. .Thus only one plate can be powdered at a time and no time is saved over hand-powdering.

In my new machine a number of plates of various or assorted sizes and of mixed types, such as line work, half tones, benday, or combinations of these, on zinc or copper, may be placed simultaneously on the machine and all automatically powdered four ways before removal. Thus a dozen plates may be powdered simultaneously, in approximately the space of time commonly required for the powdering of o ne plate. After the machine is heated up and ready for use, the operator has but to place the plates to be powdered on the machine, one after the other, up to the full capacity of the machine, which may-for examplebe twelve plates, and without further attention on the part of the operator the machine will completely powder all plates four ways, and

will announce by means of an alarm the completion of the plate first placed on the machine.

There are sections or portions of my new powdering machine performing individual operations on the plates being powdered, which form the subject matter of divisional or continuation applications, as follows: The device for straightening warped plates forms the subject matter of my divisional application Serial No. 589,399, filed January 28, 1932; the resist applying and recovering device forms the subject matter of my divisional and continuation application Serial No. 693,905, filed October 17, 1933.

Having fully described my invention, one preierred embodiment thereof, and its method of operation, I will now state what I claim to be new and novel and for which I pray that Letters Patent be granted.

I claim:

l. In a machine for powdering photo mechanical printing plates for etching, the combination of resist applying means, burning in means, means for applying a cooling liquid to the back of the plate, and plate rotating means, and automatic means for simultaneously conveying a plurality of the plates into operative relationship therewith consecutively and repeatedly.

2. In a, machine for powdering photo mechanical printing plates, the combination of means for applying resist to the surface. of the plate, means for removing the excess resist, means for compacting the residual resist against the shoulders of the design on the plate, means for heating the plate, means for applying cooling liquid to the back of the plate, means for restraining the plate against warping while cooling, and means for conveying the plate progressively to, through and from the several said means and returning the plate to its starting point.

3. In a machine for powdering photo mechani- 40 cal printing plates the combinationv of resist applying, resist backing, heating, water cooling, warp restraining and plate turning instrumentalities, arranged in operative succession.

4. In a machine for the purpose set forth, the combination of powder applying, powder fusing, plate cooling, plate straightening and plate rotating instrumentalities, arranged in operative succession.

5. In a machine for the purpose set forth, the combination of powder applying, powder fusingl plate cooling, plate straightening and plate rotating instrumentalities, with plate conveying' means arranged to pass the plate through the said instrumentalities and deliver it at the initial starting point, arranged in operative succession.

6. In a machine for the purpose set forth, the combination of la powder distributor, rotating powder removing and powder packing brushes, means for conveying a plate to be etched into operative relationship with said distributor and brushes, a powder fusing means, a second conveying means, arranged to pass the plate from its point of discharge from the rst conveying means into, through and out of operative relationship with said powder fusing means, a transfer and rotating means arranged to transfer the plate.

it into, through and out of operative relationship with said cooling means and plate straightening means, and transfer means for conveying the plate from the point oi-its discharge by the said third conveying means into operative relationship with the first mentioned conveying means at the place of beginning.

7. In a machine for the purpose set forth, the combination of plate cooling and plate straightening means, consisting of a plurality oi' rollers having water absorbent surfaces arranged to be wetted by partial immersion in water, rollers positioned above the first mentioned rollers and alternatingtherewith, and conveying means for passing the plate to be cooled and straightened between the two said sets of rollers.

8. In a machine for preparing photo mechanical printing plates to be etched, the combination of cooling means, including means for applying cooling liquid to the back of the plate, plate straightening means, arranged in .operative succession, and means for conveying a plurality of plates consecutively into operative relation with each of said means in succession in a plurality of similar recurring closed cycles.

9. A machine for applying powdered resist to photo mechanical printing plates to be etched, comprising in combination, powder rapplying means, burning in means, cooling means including means for applying cooling liquid to the back ofthe plate, arranged in operative succession, and means for conveying a plurality of plates consecutively into operative relation with each of said means in succession in a plurality of similar recurring closed cycles.

10. A machine for applying powdered resist to photo mechanical printing plates to be etched, comprising in combination, powder applying means, powder packing means, burning in means, cooling means, arranged in operative succession, and means for conveying a plurality of plates consecutively into operative relation with each of said means in succession in a plurality of similar recurring closed cycles.

11. A machine for applying powdered resist to photo mechanical printing plates to be etched, comprising in combination, powder applying means, powder recovering means, powder packing means, burning in means, cooling means, ar-

ranged in operative succession, and means for conveying a plurality of plates consecutively into operative relation with each of said means in succession in a plurality of similar recurring closed cycles.

12. A machine for applying powdered resist to photo mechanical printing plates to be etched, comprising in combination, powder applying means, excess powder removing means, powder packing means, burning in means, cooling means, arranged in operative succession, and means for conveying a plurality of plates consecutively into operative relation with each of said means in succession in a plurality of similar recurring closed cycles.

13. A machine for applying powdered resist to photo mechanical printing plates to be etched, comprising in combination, powder applying means, powder recovering means, excess powder removing means, powder packing means, burning in means, cooling means,\arranged in operative succession, and means for conveying a plurality of plates consecutively into operative relation with each of said means in succession in a plurality of similar recurring closed cycles.

14. A machine for applying powderedresist to photo mechanical printing plates to be etched, comprising in combination, powder applying means, excess powder removing means, powder packing means, burning in means, cooling means,

plate rotating means, arranged in operative succession, and means for conveying a plurality of plates consecutively into operative relation with each of said means in succession in a plurality .of similar recurring closed cycles.

15. A machine for applying powdered resist to 10 photo mechanical printing plates to be etched, comprising in combination, powder applying means, powder recovering means, excess powder removing means, powder packing means, burnmeans, powder recovering means, powder packing means, burning in means, cooling means, plate 25 rotating means, arranged in operative succession, andI means for conveying a plurality of plates consecutively into operative relation with each of said means in succession in a pluralityof similar recurring closed cycles.

17. A machine for applying powdered resist to photo mechanical printing plates to be etched, comprising in combination, powder applying means, powder packing means, burning in means, cooling means, plate rotating means, arranged in 85 operative succession, and means for conveying a plurality of plates consecutively into operative relation with cach of said means in succession in a plurality of similar recurring closed cycles.

18. A machine for applying powdered resist to 40 photo mechanical printing plates to 'be etched, comprising in combination, powder applying means, excess powder removing means, powder packing means, burning in means, cooling means, plate rotating means, plate straightening means, arranged in operative succession, and means for conveying a plurality of plates consecutively into .operative relation with each of said means in succession in a plurality of similar recurring closed cycles.

19. A machine for applying powdered resist to photo mechanical printing plates to be etched, comprising in combination, powder applying means, powder recovering means, powder packing means, burning in means, cooling means, plate rotating means, plate straightening means, arranged in operative succession, land means for conveying a plurality of plates consecutively into operative `relation with each of said means in succession in a plurality of similar recurring closed cycles.

2U. A machine for applying powdered resist tol photo mechanical printing plates to be etched, comprising in combination, powder `applying means, powder packing means, burning in means, cooling means, plate rotating means, plate straightening means, arranged in operative succession, and means for conveying a plurality of plates consecutively into operative relation with each of said means in succession in a plurality of similar recurring closed cycles.

21. A machine for applying powdered resist to photo mechanical printing plates to be etched, comprising in combination, powder applying means, arranged in operative succession, andv means for conveying a plurality of plates consecutively into operative relation with each of said means in succession in a plurality of similar recurring closed cycles.

22. A machine for applying powdered resist to photo mechanical printing plates to be etched, comprising in combination, powder applying means, powder packing means, burning in means, cooling means, plate straightening means, arranged in operative succession, and means for conveying a plurality of plates consecutively into operative relation with each of said means in succession in a plurality of similar recurring closed cycles.

23. A machine for applying powdered resist to photo mechanical printing plates to be etched, comprising in combination, powder applying means, powder recovering means, excess powder removing means, powder packing means, burning in means, cooling means, plate rotating means, plate straightening means, plate drying means, arranged in operative succession, and means for conveying a plurality of plates consecutively into operative relation with each of said means in succession in a plurality of similar recurring closed cycles.

24. A machine for applying powdered resist to photo mechanical printing plates to be etched, comprisingin combination, powder applying means, powder recovering means, powder packing means, burning in means, cooling means, plate rotating means, plate straightening means, plate drying means, arranged in operative succession, and means for conveying a plurality of plates consecutively into operative relation with each of said means in succession in a plurality of similar recurring closed cycles.

25. A machine for applying powdered resist to photo mechanical printing plates to be etched, comprising in combination, powder applying means, excess powder removing means, powder packing means, burning in means, cooling means, plate rotating means, plate straightening means,

plate drying means, arranged in operative succession, and means for conveying a plurality of plates consecutively into operative relation with each of said means in a plurality of similar recuring closed cycles.

26. A machine for applying powdered resist to photo mechanical printing plates to be etched, comprising in combination, powder applying means, powder recovering means, excess powder removing means, powder packing means, burn- 10 ing in means, cooling means, plate rotating means, plate drying means, arranged in operative succession, and means for conveying a plurality of plates consecutively into operative relation with each of said means in a plurality of similar recurring closed cycles.

27. A machine for applying powdered resist to photo mechanical printing plates to be etched, comprising in combination, powder applying means, powder recovering means, excess powder removing means, powder packing means, burning in means, cooling means, plate straightening means, plate drying means, arranged in operative succession, and means for conveying a plurality of plates consecutively into operative relation with each of said means in succession in a plurality of similar recurring closed cycles.

28. A machine for applying powdered resist to photo mechanical printing plates to be etched, comprising in combination, powder applying means, powder recovering means, excess powder removing means, powder packing means, burning in means, cooling means, plate drying means, arranged in operative succession, and means for conveying aplurality of plates consecutively into operative relation with each of' said means in succession in a plurality of similar recurring closed cycles.

29. In a machine for powdering photo mechanical printing plates for etching, the com- 40 bination of resist applying means, burning in means, means for applying a cooling liquid to the back of the plate, and plate rotating means, and automatic means for simultaneously conveying a plurality of the plates into operative relationship therewith consecutively and repeatedly.

FRANK T. POWERS.