US2883961A - Device for coating and treating body surfaces, especially as applied to printing rolls - Google Patents

Description

Apl'ilzs, 1959 R. KAULEN ETAL 2,883,961

DEVICE FOR COATING AND TREATING BODY SURFACES, ESPECIALLY AS APPLIED TO PRINTING ROLLS Filed April 21. 1954 FIG.2

INVENTORS ATT'Y5.

R. IKAULEN 14/ KROHE BY I United States Patent DEVICE FOR COATING AND TREATING BODY SURFACES, ESPECIALLY AS APPLIED T0 PRINT- ING ROLLS Robert Kaulen, Lovenich, near Koln, and Walter Krohe, Leverkusen, Germany Application April 21, 1954, Serial No. 424,655

Claims priority, application Germany April 29, 1953 2 Claims. (Cl. 118-320) This invention relates to a device for coating and treating body surfaces, especially as applied to printing rolls.

The hitherto known devices for coating the surface of bodies, especially printing rolls, with a layer sensitive to light are formed in such a manner that the light sensitive fluid is disposed in a narrow channel and the printing form or roll with the surface to be coated is moved transversely to the longitudinal axis ofthe channel past its discharge opening so that the fluid may pass over from the discharge opening to the body to be coated due to the surface tension of the liquid.

To obtain unobjectionable work, it is necessary that the layer is applied to the printing form not only completely uniformly but that the fluid itself is Without any impurity as well as without any elements impairing the uniformity of the layer or without any phenomenon, such as the formation of bubbles. The fact that the fluid is not completely pure and homogeneous in itself, acts unfavorably in the transmission of the light sensitive fluid to the printing form and to the thickness of the layer. It has been attempted heretofore to obtain an improvement wherein the channel is provided with an enlarged opening to secure uniform supply of the fluid over the Whole length of the discharge opening. The enlarged opening was shaped triangular-1y in such a manner that the sides of the triangle converged in the direction of the discharge opening. With this construction, however, it is diflicult to keep the channel clean. Under these circumstances, the cleaning agent remained in the corners of the triangle whereby the composition of the copying solution was impaired.

Feeding of the copying solution into the channel may likewise be made with difficulty, as it has not been possible to prevent the formation of bubbles in the copying solution. In the transfer of the solution, the bubbles are passed over to the printing form. But a layer on the printing form which contains bubbles presents a considerable disadvantage. Further, it is important that the copying solution in the channel and in the discharge opening as well and preferably also the printing form be kept at a uniform temperature. In printing forms having a great length, as for instance, two meters, which necessitate a channel of a corresponding length, it has not been possible until now to uniformly keep all parts during the coating process at a constant and definite temperature, in an unobjectionable manner.

The present invention has for its object a device by means of which the above-mentioned drawbacks may be overcome. It is the purpose of the invention to secure an unobjectionable transfer of the light sensitive layer to the surface of the printing form. According to the invention, the channel constructed in cross-section includes a narrow discharge opening with an adjacent enlargement whose walls converge downwardly. The enlargement may likewise have an isosceles triangular form but in such a manner that the base of the triangle is directed downwardly. The enlargement is preferably heart-shaped 2,883,961 Patented Apr. 28, 1959 ice in cross-section. This construction has the advantage that foreign matter or decomposition products may collect in the feeding channel at one place, namely, the lowermost point whereby the channel may be kept clean very easily. Furthermore, the collection of cleansing agents in sharp angles is avoided.

As copying solution is withdrawn from the channel during coating of the printing form, the channel must be constantly filled up with fresh solution. To prevent the formation of bubbles in the solution during filling up or carrying over of air with the solution, the supply container is provided according to the invention with an outlet sleeve which tapers constantly towards the discharge pipe. The outlet sleeve is preferably funnel-shaped. The container may additionally be inclined in opposite direction to the outlet sleeve. Such construction of the outlet sleeve prevents the air from damming up during the discharge of the solution. The feeding of the copying solution through the channel is effected without the formation of bubbles.

The channel as well as the supply container are surrounded by a jacket filled with a liquid or the like which serves for keeping the solution at a constant temperature. To provide that the copying solution and the printing form have the required and absolutely uniform temperature for the whole duration of the coating process, the jacket of the enlargement and of the container as Well as the hollow space within the printing form are connected with a common rotary pump, whereby the printing form and the channel are kept at a uniform temperature. The transfer of the copying solution to the printing form and the formation of the layer of the solution on this form cannot be impaired by a difference of temperature.

In the accompanying drawing is illustrated by way of example a preferred embodiment of the invention.

Fig. 1 shows diagrammatically a cross-section of the device according to the invention for coating a printing roll.

Fig. 2 is a diagrammatical longitudinal section and showing a supply container as a part of the invention.

The device for coating and treating of printing forms, as, for instance, a printing roll, is essentially arranged in such a manner that the printing roll 1 is carried past or rotated above a discharge opening 2 which contains the treating medium. The slot-like discharge opening 2 communicates with an enlarged channel or chamber 3 so that sufiicient medium may always be fed to the discharge opening 2 over the whole length of the same. The lateral walls of channel 3 converge downwardly and a collecting groove 4 is formed at the lowermost point thereof, regardless of the specific cross sectional form of the chamber. The whole device is surrounded by a jacket 5 so that the contents of the discharge opening 2 and of the chamber 3 may be kept uniformly at a predetermined temperature by means of a liquid or the like flowing through the jacket.

The discharge opening 2 should be made as narrow as possible. Its width is preferably about 2 mm. up to 5 mm. at most. The copying solution has a certain viscosity so that the solution issues with a surface curved upwards over the edges of the discharge opening 2. The coating of the printing roll 1 is effected in such a manner that upon approach of the roll to the head projecting somewhat above the discharge opening, the solution is taken along by the continued movement of the surface of the printing form and adheres to the surface thereof. When taking along the solution, all impurities or bubbles contained in the solution are passing over so that it is absolutely necessary that the solution is supplied free from bubbles and impurities.

Fig. 2 illustrates an advantageous construction of the feeding device. The supply container 6 is provided with an outlet sleeve 7 which tapers uniformly to its free end so that upon feeding the solution from the container the air cannot dam up but escapes freely. This effect may still be improved by inclination of the container 6. In this manner is obtained a whirl-free discharge from. the container 6 and feeding to an overflow space 8 airanged at one end of the channel 2 and chamber 3. The solution flows in a constant stream from the container 6 to the overflow space 8, whereby the formation of air bubbles is effectively prevented. The construction of the supply container according to the invention has the further advantage that the same may be easily cleaned. There are no sharp angles, and for this reason, impurities are kept away from the solution.

The supply container is likewise suitably surrounded by a jacket 9 so that the stored solution may be kept at a predetermined temperature. To prevent unequal cooling or heating of the solution between the supply container, including channel 2 and chamber 3 and the printing form 1, all jackets and the hollow space 10 within the printing roll are connected with one another and are preferably connected with a common rotary pump. By means of a cooling or heating liquid which constantly circulates through all jackets there is secured an absolutely uniform temperature of all mediums or parts operatively associated with one another during the coating process.

Having set forth our invention in accordance with a preferred structural embodiment thereof, What we claim and desire to secure by U. 5. Letters Patent, is:

1. A device for coating and treating body surfaces of substantially cylindrical form, particularly printing rolls, while rotating about its longitudinal axis, comprising a horizontally elongated hollow body having axially extending walls so disposed as to provide an axially elongated relatively narrow solution discharging channel having a mouth disposed at a predetermined uniform distance from the rotating cylindrical surface to be coated, said walls further providing a solution chamber beneath and in direct communication with the inlet to said narrow channel, and being laterally bulged to form a passage for a substantially unrestricted flow of said solution to the entire length of said channel, said walls then converging downwardly to form a substantially deep groove along the bottom of said chamber for the collection of impurities by settlement into this substantially quiescent portion of the chamber.

2. A device according to claim 1, wherein the cham' her is substantially heart-shaped in cross-section and provided with a jacket extending upwardly over the sides of said channel to its mouth, whereby a uniform temperature control may be possible over the solution supply through the chamber and channel to the body surface for a coating at the controlled temperature.

References Cited in the file of this patent UNITED STATES PATENTS 286,402 Duke Oct. 9, 1883 1,961,827 Rutkoskie June 5, 1934 2,124,085 Schubert July 19, 1938 2,136,468 Rosebush Nov. 15, 1938 2,342,284 Kinball et al Feb. 22, 1944 2,351,271 Leguillon June 13, 1944 2,352,149 Gautier June 20, 1944 2,357,476 Kaulen Sept. 5, 1944 2,371,871 Burckhardt Mar. 20, 1945 2,409,872 Krueger Oct. 22, 1946 2,681,294 Beguin June 15, 1954

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