US2388762A

US2388762A - Plate burner

Info

Publication number: US2388762A
Application number: US475570A
Authority: US
Inventors: Frank T Powers
Original assignee: Individual
Current assignee: Individual
Priority date: 1943-02-11
Filing date: 1943-02-11
Publication date: 1945-11-13
Anticipated expiration: 1962-11-13
Also published as: GB583860A

Description

' Nov. 13, 1945. F, T, POWERS 2,388,762

PLATE BURNER Filed Feb. 11, 1943 ATTORNEY Patented Nov. 13, 1945 U N I TED STATE S PATE N T O F'FI'C E :PLATE BURNER Frank T..Powers, Glen Cove, .Y. Application February 11, 1943, Serial No. 475,570

(01. zsa-s) 2 Claims.

The present invention relates to plate burners and more particularly to novel and useful improvements in machines for heating and melting the resinous powdered material-applied to a partial-ly etched photoengraved plate between the various etching steps.

Objects and advantages of the invention will be set forth in part hereinafter and in part will be obvious hereifrom, or may be learned by practice with the invention, the same being realized and attained by -means of the instrumentalities "and combinations pointed out in the appended claims,

, The invention consists in the novel parts, constructions, arrangements, combinations and improvements herein shown and described.

The accompanying drawing, referred to herein and constituting a part hereof, illustrates one embodiment -of the invention, and together with the description, serves to explain the principles of the invention.

Of the-drawing:

Figure 1 is a diagrammatic side "elevation of a typicaland illustrative embodiment of the invention;

Figure 2 is a sectional -view taken on the line 2-2 of Fig. 1; and

Figure 3 is a sectional view looking upwardly "and takenon' the 'line -33 of Fig. 2. r

The present inventionhas forits object the provision of a novland improved plate burn- -ing machine foruse in the photoengraving process. -A further object of'the present invention is the provision of an improved apparatus for heating andmeltingthe powdered resinous ma- "terial "applied to the surface of the plate at various stag-es in'the process of etching a'line or halftbne engraving. The invention also provides an apparatus for burning the surface of the plate withoutheating the-metal of the plate to a relative high temperature. Another object of the invention is the provision of an improved burning-in apparatus "which is capable of producing improved photoengraved plates.

In 'the process of p'hotoengraving, the plate of copper, zinc or other metal which has been provided with a developed print of photosensitive resist or enamel and *has been given a light -pre'liminaryetch, is powdered four separate times in different directions with dragons blood or other suitable resin, and *after each powdering operation, theplate must be heated to melt the resin and cause the resin powder to adhere to ithe sides :of "the etched portions of the plate, :thereby'strengtheningthe'resist and allowing the 5 plate 'tobe further etched without serious undercutting. This process is well known, and formsof apparatusfor carrying it out is shown in my :prior Patents No. 1,520,720 and No; 2,017,510. .In certain respects the present invention is an improve- *ment upon the'apparatus of my prior patents, but

it is also applicable to other forms of apparatus for the burning in of photoen'graved plates.

In accordance with the present invention, means are provided for supporting a partially etched and powdered photoengraved plate, such as a half-tone 'or line photo-engraving, and this plate is supported with its partially etched and powdered surface facing upwardly. Immediately above the surface of the plate and extending across the plate, and if desired, covering the entire surface of the plate, are a plurality of radiant gas burners facing downwardly towards the etched and powdered surface of the plate, and these burners are preferably positioned closely adjacent to each other so as to form almost a continuous uniformly heated surface which radiates an intense heat on to the upper "surface of the plate bearing the enamel and the powdered dragons blood or other resin to be melted. I

Where the plate is positively moved at a substantially uniform rate beneath the heater, only a narrow series of burners extending across the entire path of movement of the plate need be provided, but if desired, the burners may extend over an area which is somewhat larger than the area of the plate to be burned in. I These radiant gas heaters are preferably supplied with pre-mixed gas and air under considerable pressure, and means are preferably provided for supplying the burnerswith this premixed fuel at a relatively low rate which maintains the burners hot and ready to come to incandescence with only a minimum time delay after the rate at which fuel is supplied is increased when the plate is to be burned in. Where the plate is to be manually placed beneath the radiant heaters, the fuel supply may be manually controlled, but when the plates are to be fed automatically into and out of the heater, automatic means are preferably provided for increasing and decreasing the supply of premixed fuel in timed relation with the movement of the plate withrespect to the burners. Suitable refractory insulating material is preferably provided above and beneath the plate and burners and at its sides to conserve the heat and prevent damage to the remainder of the apparatus.

Referring now in detail to the illustrative embodiment of the invention as shown in thedrawing, where it is shown as forming a part of an automatic powdering and burning in machine, there is provided a support for the partially etched and powdered photoengraved plates, comprising a chain conveyor l having rollers I2 which run on the longitudinally extending angle iron tracks l4, the two chain portions being interconnected by means of plate supporting cross bars l6. The chains ID are driven at a relatively low speed and the plate is received on the conveyor from the powdering apparatus after each powdering operation has been completed, and conveys the plate through theburning in portion of the apparatus and thence to the cooling apparatus. The powdering and other portions of the completely automatic apparatus are not shown as they form no part of the present invention.

For burning in the powder applied to the sides of the dots or lines of the half tone or line photoengraving there is provided a burning-in chamber having a bottom 26 and side and end walls 22, of refractory material such as fire brick, the end walls 24 being provided with a narrow slot 25 through which the conveyor chain introduces and removes th partially etched and powdered plates.

Immediately above the conveyor chain, and spaced a convenient distance from the plates carried by the conveyor chain are provided a plurality of radiant gas burners 26 which are fed with premixed fuel through the pipe 30 and the main supply pipes 32. These burners 26 are preferably directed downwardly so that the heat radiated from them falls directly upon the partially etched and powdered surface of the photoengraved plates I! as these plates are carried along by the conveyor. The individual radiant burners 26 ar preferably spaced closely together so as to form a substantially continuous, highly heated radiant surface which is of a width corresponding to the maximum width of plate to be burned in.

As illustratively embodied the heaters are formed of a hexagonal piece of refractory material 34 enclosed within a metallic supporting sheath 36, the inner surface of the refractory being deeply dished to provide a combustion surface for the burning fuel which issues from the relatively small flutes or slots in the central portion 31 of the burner.

Means are also provided for maintaining the radiant burners 26 at a moderate heat so as to conserve gas, reduc the average temperature of the burning in apparatus, and increase the speed of operation, and for this purpose the gas line 32 is provided with a valve 38 in addition to the main shut-off valve 46. Valve 38 is normally partially open so as to allow only a moderate quantity of premixed fuel to be supplied to the burners, and means are provided for increasing the flow of fuel to a maximum by fully opening the valve 38 so as to produce the intense heat necessary for the quick burning in of the powdered resinous material on the face of the plate.

In order to automatically effect the control of the fuel supplied to the burners 26 in timed relation with the movement of the plates, the conveyor chain I0 is provided with upwardly extending members 42 immediately adjacent the trailing edge of the plates l1, and cooperating means are provided for opening the valve 38 to its maximum a short time before the plate enters the burner housing 20, 22, 24, and for reducing th opening of valve 38 as soon as the plate has been completely burned in. These means may comprise a lever 44 positioned well in advance of the burners and connected through link 46, bell crank 41 and link 48 to the valve operating lever 49 so that the valve 38 is opened sufliciently in advance of the introduction of the plate beneath the burners to allow the burners to attain their full radiant intensity, and another set of levers 56, 5| and links 52 and 53 are connected with the lever 49 so as to be operated by the projection 42 to reduce the flow of fuel after the plate has been burned in.

In the operation of the illustrative embodiment of the present invention, the previously partially etched and powdered photoengraved plate is delivered to the conveyor chain In with its etched and powdered face upwardly, and the trailing edge of the plate closely adjacent to a projection 42. As the chain moves, the projection 42 causes th valve 38 to be opened to maximum, and the already moderately heated radiant burners 26 are supplied with additional fuel to bring them to their maximum intensity of radiation by the time the leading edge of th plate I1 is introduced into the burning in chamber beneath the radiant burners 26.

As the plate passes beneath the burners 26, its powdered and partially etched surface is quickly and uniformly heated by the radiant heat from the burners, and this heat is applied directly to the powder, causing it to be quickly melted and Without substantial heating of the relatively large mass of the plate ll, while at the same time any excess powder and any powder not on the sides of the dots or lines is blown away by the relatively intense flow of air and gases from the burners. The plate is continuously progressed past the burners 26 and out into the atmosphere where it may be further cooled if desired, and as the plate is completely withdrawn from the burning-in chamber, the valve 38 is automatically moved to its partially closed position to reduce the supply of fuel so that the burners are maintained moderately hot until the next plate is to be burned in.

By reason of the fact that the heat is directly applied to the surface of the plate for only a rela, tively short time, and from a relatively intense radiant source, the powdered resinous material is almost instantaneously melted and this is accomplished without injuring the strength of the metal plate I! and without causing it to be warped by excessive heating. Once the resin has been melted, the resin is set almost immediately 7 instead of its dripping or flowing downwardly and into the intagliated spaces between adjacent dots or lines. Thereby cleaner working photoengravings may be produced, as only the sides of the lines or dots are coated with this resinous material, any excess powdered resin lying on the bottom of the intervening spaces being blown away by the relatively intense air circulation created by the flames of the radiant heaters. This is in contrast to the conventional apparatus heretofore usedin which the heat was applied to the plate as a whole, or to the underside of the plate, resulting in a heating of the powdered resinous material at the same rate as the heating of the plate. Such conventional apparatus is also disadvantageous in the quality of work produced, as well as in the fact that it was usually necessary to straighten out the plates after they had been warped by the relatively intense heat applied to them.

The invention in its broader aspects is not limited to the specific mechanisms shown and described but departures may be made therefrom within the scope of the accompanying claims without departing from the principles of the invention and without sacrificing its chief advantages.

What I claim is:

1. In a plate burner for photoengraving use, the combination of a plurality of radiant gas burners, a moving support for moving an etched and powdered plate beneath the burners, a valve controlling the supply of fuel to the burners and means operated by the moving support for controlling the valve to increase the fuel supply to the burners prior to the passage of the plate beneath the burners, and further means operated by the moving support for controlling the valve to decrease the fuel supply to the burners after the passage of the plate beneath the burners.

2. In a plate burner for photoengraving use, the combination of a plurality of radiant gas burners, a moving support for moving an etched and powdered plate beneath the burners, and a valve controlling the supply of fuel to the burners and normally supplying a sufiicient amount of fuel to keep the burners moderately hot, means operated by the moving support for controlling the valve to increase the fuel supply to the burners prior to the passage of the plate beneath the burners, and further means operated by the mov- .ing support for controlling the valve to decrease the fuel supply to the burners after the passage of the plate beneath the burners.

FRANK T. POWERS.