US1861161A - Etcher slide - Google Patents

Description

F. T. POWERS May 31, 193 2.

ETCHER' SLIDE Filed Sept. 4, 1931 TOR lNVE

Patented May 31, 1932 PATIZENT onion ETGHER SLIDE .Application'filed' September-'4, 1931. SerialNo. 561,131

"My invention relates to the art'of etching photoamechanical printing plates, and "particularly to animprovement in device "for supporting the plate during the etching operation. V j

The object of my invention is to provide a means for supporting the plate in the face down position in the etching machine, which does not require the clamping or holding of the plate in position within the etching machine while the etchant is being applied to the surface thereof.

'It 'has been generally; recognized in the photo-engraving industry that more uniform results may be obtained in the etching process with etching machines of the type in which the etchant is forcibly thrown against the plate being etched by means of paddle wheels, sprays or other .devices if the plate is placed in a horizontal position with its face downward,- and manyetching machines have been built upon thisprinciple,

The reasons for the superiority of this method of etching over the other methods in which the plate is supported either in a vertical or an inclined position, or inahorizontal,jface up position, are obvious. I When the plateis supported in 1a vertical'or'substantially vertical position, and the etchant is projected or spraye'd against the surface of the plate, that portion of the etchant which strikes the"upperipart of the plate flows down over'rthe surface of the plate to the :35 bottom; This stream or layer ofetchant on the lowerpart of theplate has two obj ectionable actions or effects upon theetching. First,'it forms a blanket on'the surface of the plate, preventing the fresh etchant'wliich is projected or sprayed against this part of the plate from reaching tliesurface ofthe plate. This'blanketing action results in a different type of etching occurring on the lower part of the plate than that which takes place onvthe'upperpart of the plate where the; projected etchant strikes forcibly directly on the :plate, without any bufiering or blanketing effect of a layer of etchant 'flowing over its surface.-

:'Second, the upper' and lower parts of a plate etched in this manner get different treatments because the upperpart is subjected 'to directaction of the forcibly projectedoz sprayed-etchant while the-lower part is largely etched by' fluid flowing down over its face, with the result that in the lower part ofthe plate the upperside of the lines or dots are attacked more actively than the underside sincetheflow of the etchant is always downward. The result is that it is customary in machines of this type' to 'fre-' quently turn 'theplate to anew position in order to equalize" the etching action. During the process of etching the operator must frequently stop -his' machine and turn the plate either 180 degrees or degrees to overcome this unequal action.

"In many types of machines a mechanical turningdevice is provided for the'purpose of overcoming this uneven etching'action. All such mechanical devices require clamping or otherwise fastening the plateto the support, and sincetheplates vary greatly in size these devices must be adjustable, and hence more or less complicated.

' These clamping 'devices are objectionable for several reasons. They get out of order. Theyare cumbersome to handle. A They stick and jamb. They are'wet with the etching fluidand so make it necessary for the operator to-protect' his hands by gloves or other-" wise, if theetchant is to be kept from the hands. Theyinot infrequently work loose and permitthe plate to fall into the machine, sometimes on the paddle wheel, wrecking it. They usually require'screws, clamps or other devices'which are difficult to construct of maand more uniform etch over the entire surface of the plate.

When the plate is supported in a horizontal position face down, as it is in a number of the etching machines heretofore in use,

it is also necessary to employ some type of adjustable clamping or holding device, which will receive and hold any size of plate which it may be desired to etch, as described above.

My invention eliminates all these difficulties inherent in the heretofore used types of plate holders in etching machines.

In the accompanying drawings is shown a preferred embodiment of my invention from which variations may be made without departing from its spirit.

In the drawings like numbers refer to the same or similar parts and arrows indicate the direction of movement or rotation. Fig. 1 is a side view, partially in section, of the completed machine. Fig. 2 is a front view also partly in section.

Fig. 3 is an isometric perspective of the plate support. Fig. 4 is a section of the plate support on the line a-b. Figs. 5 and 6 are details of alternate types of supporting elements. Fig. 7 is a cross section of the supporting element shown in Fig. 6.

In the drawings, 1 is a tank or receptacle of material immune to the action of the etching fluid to be used. Within the tank is a paddle wheel or spray producing element, 2, of well known construction, supported on a shaft, 3, carried by bearings, 4. Within the tank, 1, is placed a suitable etching fluid which will vary with the kind of material to be etched. The level of the top of the fluid in the tank is such that the tips of the paddle wheels dip into the fluid as they revolve and throw it forcibly against the plate to be etched.

On one of the ends of the shaft, 3, are two pulleys 5 and 6. The pulley, 5, is operatively connected by belt, 7, to the pulley 8, of the electric motor, 9, or to any convenient source of power. The pulley, 6, is connected by the round belt, 10, to the pulley, 11, on the shaft, 12. of the centrifugal fan, 13, located in the hood. 14, which covers the top of the tank, 1. In the upper portion of the tank, 1, is an opening, 15, through which opening a plate support, 16, slides on Ways, 17, attached to the inner surface of the slides of the tank. Within the hood, 14. are positioned baflles. 18, 19 and 20, so arranged that spray from the paddle Wheel, 2, is completely intercepted, but allowing the free passage of air or gases from the lower to the upper portion of the hood. The plate support, 16, is constructed as shown'in detail in Figs. 3 and 4. The frame of the plate support is preferably rectangular in plan having an outer frame, 21, and a plurality of cross members, 22, having a thin section and having a concave or depressed profile along the upper edges. The

- file of the cross members, 22, and also a small plate, 24, similarly resting. The thickness of the cross members, 22, is so small that they do not interfere to any discoverable degree with the uniformity of the etch obtained on the surface of the plate. The direction of the travel of the spray of etching fluid, as

indicated by the arrows in Figs. 1 and 2, is parallel to the plane of the surfaces of the cross members, 22, and the distance or clearance under the plate between the plate and the cross members permits the etchant to act freely upon the very narrow strips of the surface of the plate, which lie directly above the thin cross members.

Figs. 5 and 6 show two alternate forms of supports, which also embody the spirit of the invention. In Fig. 5 the cross member has a V shaped, depressed upper profile, which functions in a manner similar to the curved upper profile of the cross member 22 shown inFigs. 2, 3 and 4, and will receive a plate of any size to be etched in a face-down position without any portion of the plate except the two opposite outer edges coming into contact with the supporting cross members. In 6 the cross member, 26, consists of a flattened wire of suitable size and stiffness bent to a downwardly curved form, similar to the depressed upper profile of the cross members, 22. This flattened wire form of support may have a cross section similar to that shown in Fig. 7 or it may have a variety of other shapes without departing from the spirit of my invention.

These cross member of whatever form are so spaced apart that plates of any desired size from the smallest to the largest may be safely supported thereon without danger of falling between the cross members.

The result is a uniformly etched surface obtained without rotating the plate or changing its position either by hand or by mechanically operated means, as has been the universal custom heretofore.

I thereby secure the advantages of the superior and more uniform results of the facedown position of etching, which are described above, together with the simplicity and convenience of handling and placing ofthe vertical position without the disadvantages of either.

Having described my invention and the construction of some of the preferred forms thereof, so that one skilled in the art may no make and use the same, I shall now state what I claim to be new and novel, and for which I pray that Letters Patent be granted.

I claim:

1. In a machine for etching photo-mechanical printing plates, the combination of a receptacle for the etchant, a spray producing means, a cover to confine the spray, and a movable plate supporting member, which is characterized by having a plurality of cross members of thin material positioned with their sides parallel to the planes of travel of the sprayed etchant and having depressed upper edges adapted to support the plates by contacting only with their opposite edges, substantially as described.

2. A plate supporting member for supporting plates in a face down position for use in a machine for etching photo-mechanical printing plates, which is characterized by having a plurality of cross members with depressed upper profile adapted to support the plates by contacting onlywith their opposite edges, substantially as described.

3. A plate supporting member for supporting plates in a face-down position in a machine for etching photo-mechanical printing plates, which is characterized by an outer frame to which are attached a plurality of cross members having a depressed upper profile of curved form adapted to support the plates by contacting only with their opposite edges, substantially as described.

Signed at New York city, in the county of New York, and State of New York, this 24th day of August, A. D. 1931.

FRANK T. POWERS.

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