US1147145A - Apparatus for etching printing-plates. - Google Patents

Description

A. H. COOMBS. APPARATUS FOR ETCHlNG PRINTING PLATES.

APPLICATIONIFILED MAY 26. 1913- 1,147, 145. Patented July 20, 1915.

COLUMBIA PLANOCIRAPH RIO-,WASHINGTON. D. c'.

J OFFICE.

APPARATUS FOR ETGI-IING- PRINTING-PLATES.

specification of Letters Patent. Patented July 20, 1915.

Application filed Ma 26,1913. seriainojzeasis. 7

To all whom it may concern:

Be it known that I, ARTHUR H. COOMBS, a citizen of the United States of America, and a resident of Chicago, county of Cook,-and State of Illinois, have invented certainnew and useful Improvements in Apparatus for Etching Printing-Plates, of which the following is a specification.

-The main objects of this invention are to provide an apparatus for use in etching relief plates in printing, adapted to prevent undercutting of the relief portions of the plates and to permit the plates to be etched with rapidity and evenly. 7

An illustrative embodiment of this invention is shown in the accompanying drawings, in which Figure 1 is a side elevation partly in section of an apparatus constructed according to this invention. Fig. 2 is a transverse vertical section of the same. Fig. 3 isan end View.

. It is known that in etching plates undercutting may be avoided to a great extent by quickly etchingthe plates in a solution of comparatively strong acid, but this method has the disadvantage that the plates are not always evenly etched. It is also known that the plates may be more evenly etched by immersing them for a considerable length of time in a weak acidsolution, but in this process undercutting occurs to an undesirable extent and the process requires too much time to be practical for many classes of work.

Thepresent invention relates to an apparatus for causing, a flow of acid in varying directions over a substantially horizontally disposed plate, whereby little if any undercutting occurs and the plate may be etched evenly and with rapidity. To further. this end the apparatus is designed toautomatr cally tilt from side to side, so that the etching solution may act evenly on various portions of the plate.

Printing plates are sometimes etched whe resting on edge in an upright position, while the etching liquid is permitted -to run down over the surfaces of the plates, but by this method there is danger of uneven etching and undercutting. The undercutting with this arrangement may be due to the tendency of the liquid to run more around the edges of raised parts of the plates than to run evenly over its entire surface. The latter may more easily occur when the plate lies in a substantially horizontal position.

Referring to the drawings, a suitable supporting frame 1 for theentire apparatus is shown with a pair of bearings 2 and 3, through which passes a horizontally disposed shaft'l. Between the bearing 3 and the shaft is a rotatable sleeve 5 to which is rigidly secured a ulley 6 and a reel-shaped receptacle frame consisting of a pair of star-shaped end piecesS and 9 and a plurality of tie-rods 10. The end piece 8 is rotatable upon-the shaft l while the end piece 9 is secured to sleeve 5 "Supported in the frame 7 between the rods 10 is a cylindrical receptacle 11 consisting of non-corrosive material, such as earthen-ware, or it may be made of metal lined with porcelain or some other acid resisting material. The receptacle 11 preferably has closed ends 12, but is provided with a rectangular opening 13 which is normally closed by a glass lid 14 hinged to one of the rods 10 at one side, and clamped in its seat at the other side by means of clamps 15. The lid 14 is preferably provided with an elastic gasket 16, as shown in Fig. 1. Thereceptacle 11 is provided with a plurality of bucket or cupshaped projections 17 extending along its length and suitably formed to provide pockets 18 by means of which the etching acid 19 may be lifted from the bottom of the receptacle and deposited on the article to be etched, indicated by broken lines 20 (Fig. 2), resting'on a suitable supportingtray'21. This liftingof the acid is eflected by rotating the receptacle'1l,as described further on. The tray 21 is rigidly secured to shaft 4:, and like the casing of the receptacle 11 is made of acid resisting material. The shaft 4 at its left hand edge (Fig. 1), preferably outside ofthe receptacle 11, carries a pendulum 22 which may be formed by bending the shaft 4, as at 23, and securing to the end of the shaft a weight 24. The functionof the pendulum is to govern the rocking offthe tray 21 from side to side when the tray is set in motion by the deposit of etching liquid thereon. i

The tray 21 may be provided with up wardly extending flanges 25 at its edges to prevent the plate which is being etched from slipping relative of the tray. The tray preferably also has perforations 26 so that the acidmay normally drain outthetray, and to provide means whereby the etched plate may readily be removed from the tray. The tray 21, as shown in Fig. 1, may be made to extend'along almost the entire length of the receptacle 11, and to overhang at its ends 27 inwardlyextending bosses 28 integral with the ends 12 of the receptacle 11. At its inner end each boss is provided with an annular flange 29 extending radially of shaft 4:, whereby any acid that may be thrown against the end walls 12 and drip downwardly on bosses 28 will drip off of flanges 29 rather than make its way to shaft 4 between bosses 29 and the tubular part 30 of tray 21 through which shaft 4 passes. The overhanging extensions 27 of the tray also assist in preventing the acid from reaching the metallic shaft 4:, and thereby corroding the latter.

To operate the device the etching fluid may be introduced through the opening 13 in casing 11, and the plate to be etched is also passed through this opening and permitted to rest on tray 21. Then the lid 14:

is tightly clamped in its closed position putting the device into condition for operation. To perform the etching operation the cylindrical receptacle 11 is rotated by power ap plied at the pulley 6, which, as before explained, is rigidly connected to the receptacle 11 by sleeve 5 which is rotatably mounted within bearing 3 on shaft 4:. Rotation of the receptacle in the direction indicated by the arrow (Fig. 2) results in the cupshaped extensions or flanges 17 each raising a certain portion of the etching fluid 19 until the projections 17 arrive above the plate 20, when the fluid flows out of pockets 18 to the plate 20 thus throwing the tray out of balance and running to one side thereof, and increasing its tendency to rock. The action of the pendulum is to normally urge the tray toward its horizontal position and thereby govern the rocking motion of tray 21 caused by the liquid which is deposited on the tray and flows from side to side. By this means the solution 19 is continually agitated while acting on plate 20, and therefore no part of the solution can for any considerable length of time act exclusively on any one part of the plate. By this means an extremely quick acting acid solution may be employed without danger of unduly acting on some portions of the plate. Undercutting of the raised portions of the plate is prevented, as before mentioned, by using a quick acting solution while not permitting the plate 20 to rest for any considerable length of time far out Copies of this patent may he obtained for of a horizontal position while the acid is acting on the plate.

Although but one specific embodiment of this invention has been herein shown and described, it will be understood that numerous details of the construction shown may be altered or omitted without departing from the spirit of the invention as defined by the following claims.

I claim 1. In an etching apparatus, the combination of a. supporting frame and a support therein, a tray for supporting articlesto be etched secured to said shaft, apendulum se cured to, said shaft whereby the tray is urged to the horizontal position, and means for pouring etching liquid on the tray whereby it isoscillated and causes the liquid to run from side to side over the-articles to be etched.

4:. In a device of the class described, the combination of a frame, a shaft journaled therein, a tray for supporting articles to be etched secured to said shaft, a pendulum secured to said shaft whereby the tray is urged to the horizontal position, and a rotatably mounted receptacle surrounding said tray,-the interior of said receptacle being provided with a pocket whereby when'the receptacle is rotated liquid may be lifted from the bottom of the receptacle and deposited on the tray.

5. In an etchingapparatus, the combination of a supporting frame, a shaft journaled therein, a receptacle frame rotatably supported on said shaft, a receptacle contained within said receptacle frame, pockets in the interior of said receptacle and rotatable therewith, meansfor rotating said receptacle, a horizontally disposed support secured to said shaft within. saidreceptacle, and a pendulum carried by said shaft.

Signed at Chicago this22nd day of May,

v 1 ARTHUR H. OOOMBS. Witnesses:

Pmmr B. WoonwoR'rH,

RUDow RUMMLER.

five cents each, by addressing the Commissioner of Patents Washington, D. G.

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