US2129904A - Apparatus for heat treating electrotype printing plates - Google Patents

Description

Sept. 13, 1938. H. M. BLAETZ 2,129,904

APPARATUS FOR HEAT TREATING ELECTRQTYPE PRINTING PLATES Filed Dec. 15; 1937 w 6 W V L Mar 51 QAAIW JIV'O/P/VEY,

Patented Sept. 13, 1938 UNITED STATES PATENT OFFICE APPARATUS FOR HEAT TREATING ELEC- TROTYPE PRINTING PLATES Application December 15, 1937, Serial No. 179,927

3 Claims.

It has been found that heating electrotyp'e printing plates to a critical temperature of about 460470 F., followed by rapid cooling (as by quenching at a temperature of 45-65 F.), produces an extreme softness of the plate alloy, followed by a rapid increase in hardness and toughness. This results in an improved printing plate which is better able to resist wear and fracture during long runs on a printing press.

Various methods of carrying out this heat treatment have been proposed and tried. One method heats the plate in oil. I have found that maintaining an oil bath at 460-470 F., causes appreciable loss of'oil by evaporation; condensation of the evaporated portion results in an oily deposit of carbon or soot on the walls and ceiling of the workroom, or on the surfaces of a ventilating hood or cover which may be provided to carry away or confine the fumes. Further, the use of the oil heating bath not only provides a fire hazard but also requires in addition to the quenching bath, the use of a cleaning solution for removing the oil film from the printing plate surfaces. These features are objectionable in practical operation, especially where large numbers of plates are heat-treated.

The use of high-boiling synthetic liquids, such as diphenyl or triphenyl oxides or mixtures of these, has also been proposed. I have found that objectionable fumes are given off at the high temperatures necessary, and that the loss of liquid would require the use of elaborate equipment for reclaiming the vapors.

Still another proposed method involves the use of chemical salts which are solid at ordinary temperatures, but which are liquid at temperatures above, say, 200 F. The use of such salts in a plate heating bath eliminates the fumes and evaporation. However, I have found that plates heated in this manner will carry a thin film of molten salt which solidifies as soon as the plate is immersed in the cold quenching medium. This film tend to prevent uniform cooling by the quenching medium. When I have tested different areas of plates so heated and quenched, I have found that the hardness is not uniform. The insulating effect of the salt film has resulted in some areas being solt and others extremely hard. It is desirable that the plate should be of uniform hardness in all areas.

I have found a simple, effective, and practical means of eliminating the objectionable features of the methods which have been discussed.

The principal objects of the present invention are to avoid the use of objectionable liquids as heating media and to eliminate dangerous fire hazards; to minimize the floor space required; to avoid undue escape of heat; to provide ready ingress and egress for the plates; to heat treat either flat or curved plates; to provide capacity 5 for treating a large number of plates and to make the operation substantially automatic.

Other objects of the invention will appear from the following description at the end of which the invention will be claimed.

Generally stated the invention comprises a tank adapted to contain water and provided with cooling means, a heat insulated conical hood closed at its top and open at its bottom and superposed above and spaced from the tank and covering a portion of the water therein, means for heating air entering the hood, heat insulated trays conforming to the shape of the printing plates and adapted to support the plates when heated and to protect the faces of the plates from over heating, a conveyor of which one flight or reach extends above the water in the tank and up into the top part of the hood and of which another flight or reach extends downwards from the top part and out of the hood and between the liquid in the tank and the first flight of the conveyor, said trays being pendent from the conveyor and presented outside of the hood for the reception of the plates and being carried by the conveyor into and up and down in the hood to heat the plates, and into and thru the water in the tank to quench the plates, and out of the water in the tank to deliver the plates.

The invention also comprises the improvements to be presently described and finally claimed. 7

In the following description reference will be made to the accompanying drawing forming part hereof and in which,

Figure 1 is a longitudinal central section of apparatus embodying features of the invention, and

Fig. 2 is a transverse vertical section of the same.

In the drawing I indicates a tank adapted to contain quenching fiuid and it is provided with cooling coils 2, it may conveniently be arranged upon the floor. 3 is a heat insulated conical hood closed at its top and open at its bottom, the hood is superposed above the tank and it may be supported as indicated for example at 4. 5 indicates means as burners for heating air entering the hood and for keeping the air in the hood hot. 6 are trays adapted to support the plates. The trays 6 may be fiat or curved in order to conform to the shape of the printing plate. The trays are faced with insulating material I, which is not affected by the liquid in the tank I, and which prevents overheating the nickle and copper shell of the plates which if overheated would cause the thin layer of tin which bonds the shell to the plate alloy to be drawn away by the antimony with the result that the bond is materially weakened if not destroyed. The trays 6 are pendent from the conveyor 8, and are presented outside of the hood toward the right in Fig. 1, for the reception of the printing plates and they are carriedby the conveyor 8 into and up and down in the hood to heat the plates, and into and thru the water in the tank I to quench the plates, and out of the water in the tank to deliver the plates. Thev trays are each provided with a laterally disposed arm 9 by which they are pendent. There are lever. elements centrally pivoted to the conveyor and to one arm ID, of which the trays are pivotally attached in generally horizontal position in all positions of the .lever elements. II are curved guides located in the path of the ends of the other arms [2 of the lever elements. These curved guides operate on the arms I2 to turn-the same so that the trays are dropped quickly into the quenching fluid as indicated toward the left of the tank I in the drawing.

If desired automatic feeding means may be employed for placing the printing plates on the trays 6, and for removing them, although such means are not shown in the drawing because they are not a part of the present invention.

The conveyor 8 passes around suitable guide wheels 13, I6, I and I6, and at l1 there is indicated means for driving the conveyor.

It will be obvious to those skilled in the art to which the invention relates that modifications may be made in details of construction and arrangement without departing from thespirit of the invention which is not limited as to such matters or otherwise than the prior art and the appended claims may require.

I claim:

1. Apparatus for heat treating electrotype printing plates comprising in combination a tank adapted to contain a quenching fluid, an open bottom hood arranged above the tank and having means for heating its interior, an endless conveyor extending into and up and down in the hood and having a flight extending out of the hood horizontally above the level of the quenching fluid, trays having insulated faces, lever elements centrally pivoted to the conveyor and to one arm of which the trays are pivotally attached and are pendent in generally horizontal position in all positions of the lever elements, and curved guides located at the entrance of said flight of the conveyor and in the path of the ends of the other arms of said lever elements to turn the same and drop the trays quickly into the quenching fluid.

2. Apparatus for heat treating electrotype printing plates comprising in combination a tank adapted to contain water and provided with cooling means, a heat insulated conical hood closed at its top and open at its bottom and superposed above and spaced from the tank and covering a portion of the water therein, means for heating air entering the hood, heat insulated trays conforming to the shape of the printing plates and adapted to support the plates when heated and to protect the faces of the plates from overheating, a conveyor of which one flight or reach extends above the water in the tank and up into the-top part of the hood and of which another flight or reach extends downwards from the top part of and out of the hood and between the liquid in the tank and the first flight of the conveyor, said trays being pendent from the conveyor and presented outside of the hood for the reception of plates and beingcarried by the conveyor into and up and down in the hood to heat the plates and into and thru the waterin the tank to quench the plates, and out of the water in the tank to deliver the plates, said trays each being provided with a laterally disposed arm by which it is pendent.

3. Apparatus for heat treating electrotype printing plates comprising in combination a tank adaptedto contain water, a heat insulated hood superposed above and spaced from the tank, means for heating the. hood, trays conforming to the shape of the printing plates and adapted to support the plates when heated, a conveyor of which one flight or reach extends above the water in the tank and up into the top part of the hood, and of which another flight or reach extends downwards from the top part of and out .of the hood and between the liquid in the tank and the first flight of the conveyor, said trays being pendent from the conveyor and presented outside of the hood for the reception of plates and being carried by the conveyor into and up and down in the hood to heat the plates and into and through the waterv inthe tank to quench the plates and out of the water in the tank to deliver the plates.

HARRY M. BLAE'IZ.

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