US2645998A - Printing plate solidifying and dimensioning method - Google Patents

Description

July 21, 1953 D. c. COTTRELL ETAL 2,645,998

PRINTING PLATE SOLIDIFYING AND DIMENSIONING METHOD Filed Jan. 3, 1949 4 Sheets-Sheet 1 LNVENTURJ J y 9 1953 D. c. COTTRELL ET AL 2, 5,99

PRINTING PLATE SOLIDIFYING AND DIMENSIONING METHOD Filed Jan. 3, 1949 4 Sheets-Sheet 2 L INVENTORS W C W By M cf cm f Yoryey July 2 1953 D. c'. COTTRELL ETAL PRINTING PLATE SOLI IIDIFYING AND DIMENSIONING METHOD 4 Sheets-Sheet 3 Filed Jan. 5, 1949 filler/75y KM RM mm NM \m A \w mm Q y 21, 9 3 D. c. COTTRELL ETAL 2 9 PRINTING PLATE SOLIDIFYING AND DIMENSIONING METHOD Filed Jan. 5; 1949 4 Sheets-Sheet 4 VAD m a i5 i4 INVENTORS W Patented July 21, 1953 PRINTING PLATE SOLIDIFYING AND DIMENSIONING METHOD Donald 0. Cottrell, Fox Point, and Carl 0. Sweet, Whitefish Bay, Wis., assignors to C. B. Cottrell & Sons Company, Pawcatuck, Conn., a corporation of Delaware Application January 3, 1949, Serial No. 68,762

3 Claims. 1

This invention relates to a method and apparatus for acting upon printing plates for the purpose of more precisely dimensioning the same, for the purpose of modifying the location of the plane of the printing face, and for the purpose of reducing lack of uniformity in density of the plate material; and it resides more specifically in an improved method and apparatus by means of which the metal alloy composing the plate is subjected to pressure induced deformation sufiicient to produce correction or modification of the plate and at the same time to establish a transitory condition of increased machinability due to cold working, and then while said transitory condition of increased machinability is still prevailing the plate is immediately leveled by subjecting the same to machining or shaving.

Heretofore printing plates such as electrotype plates, stereotype plates and the like have been acted upon with success for the purpose of more precisely positioning the plane of the printing face with respect to the back of the plate. At times this work is performed by very skillfully hand hammering the back of the plate while in contact with a true surface and thereafter machining or shaving the back of the plate, The hand hammerin of the plate requires ahigh degree of skill and is atime consumingoperation. Apparatus for mechanically correcting the plane of the printing face of a plate is in wide use. Such apparatus depends upon the use of pressing equipment which forces a plurality of small pressure points into the back of the plate while resting on a true surface. After a plate has been thus treated, to produce so-called cormotion or solidification thereof it is subsequently placed in apparatus designed to machine or shave the back of the plate to a surface which is closely parallel to the printing face of the plate.

When desired to introduce into a printing plate so-called treatment? that is to say to bring about the formation of selected areas in the printing face of the plate which are at slightly different levels, for the purpose of improving the printing effect of the plate, the plate is acted upon in a manner related to that described above, the plate being subjected to pressure sufficient to produce deformation while in contact with carefully prepared masks of proper thickness. solidification, leveling or treatment whether produced by hand hammering or otherwise are all usually followed by precise machining, or shaving of the back of the printin plate. This final cutting away of metal from the back of the plate has, however, heretofore been performed as a separate step some minutes or hours after the metal has been deformed.

It is the discovery of this invention that metal alloy such as electrotype backing metal, stereotype metal or other such alloys (usually containing lead as the chief constituent) when in the form of a printing plate and when subjected to pressure to cause deformation sufficient for the purpose of solidifying the plate or correcting or modifying the position of the plane of the printing face, that the metal alloy so deformed, momentarily acquires a transitory condition of increased machinability which permits more precise machining or shaving of the plate if machining or shaving is performed while such transitory condition is still prevailing. It is an object of this invention to provide methods and apparatus which cause shaving or machining of the plate to take place while this transitory condition of increased machinability is prevailing. This and other objects and advantages of this invention will be more fully explained in the description following.

This invention is herein described by reference to the accompanying drawings forming a part hereof wherein there is set forth by way of illustration and not of limitation one form of the apparatus of this invention suitable for carrying on illustrative instances of the method of this invention.

In the drawings:

Fig. 1 is a side view in elevation with parts broken away and in section of one form of the apparatus of this invention,

Fig. 2 is an end view in elevation of the apparatus shown in Fig. 1,

Fig. 3 is an enlarged detailed side view in elevation and in section of the upper part of the apparatus shown in Fig. 2 the same being viewed through the broken plane indicated at 3-3 in Fi 6, r

Fig. Fl is an enlarged diagrammatic detailed fragmentary side View in elevation and in section of a plate undergoing solidification, flattening and shaving,

Fig. 5 is an enlarged diagrammatic detailed fragmentary side View in elevation and in section of a plate undergoing treatment to modify its printing face and being subjected to shaving.

Fig. 6 is an enlarged detailed end View in elevation and partly in section of the upper part of the apparatus illustrated in Fig. 1, viewed in part in section through the plane 66 there indicated,

3 showing parts which act to vertically adjust the solidifying and flattening roll,

Fig. '7 is a fragmentary detailed end view in elevation and partly in section of the treating roll elevating mechanism of the apparatus shown in Fig. l, the same being viewed in part in section through the broken plane 'I'I there indicated,

Fig. 8 is a fragmentary detailed side view in elevation of the portion of the apparatus shown in Fig. l which is detailed in Fig. 7, and

Fig. 9 is an enlarged detailed view in developed form of a fragment of the surface of the solidifying roll of the apparatus shown in Fig. 1.

As shown in the drawings, particularly in Figs. 1 and 2, the form of the apparatus of this invention, there set forth for illustrative purposes, is provided with a rigid sub-base I, surmounted by a bed designated generally by the numeral 2. Extending longitudinally of the bed 2 is a pair of parallel ways 33 which support for horizontal longitudinal movement a carriage designated generally i. Bed 2 is open between and below the ways 3-3 which opening accommodates a horizontally disposed hydraulic feed cylinder 5 in which there is mounted for longitudinal movement a piston rod 6. The end of piston rod 6 cpposite cylinder 5 is connected by means of a rigid arm I to the carriage 4 for imparting horizontal movement thereto on introduction and withdrawal of hydraulic fluid into and from within the cylinder 5. Hydraulic fluid for actuation of the piston rod 6 is supplied in known manner by pump 8 driven by motor 9. The connections between the pump 8 and the cylinder 5 are not shown, but are arranged in known manner to be controlled by control lever I6 which when shifted in one direction causes movement of the carriage 4 toward the left and when shifted in the opposite direction causes movement of the carriage 4 more rapidly toward the right.

Any convenient means other than an hydraulic system may be employed to bring about movement of the carriage 4.

Enclosed within the carriage 2', in an opening provided therefor, is a vertically adjustable platen II having downwardly projecting inclined lands which slidingly engage an adjustable wedge |2 which in turn threadingly engages an adjusting screw I3. Adjusting screw I3 is rotatably mounted in the right hand end of carriage 4 and there held against end Wise movement with respect to the carriage Secured to the end of screw I3 is a hand adjusting wheel I4 by means of which the horizontal position of the wedge I2 may be adjusted. Horizontal adjustment of the wedge I2 in turn brings about vertical adjustment of the platen II.

The working stroke direction of movement of carriage 4 is toward the left as viewed in Fig. l and ther is provided near the right hand end of platen II a vertically projecting thrust lug I5 intended to engage the edge of a flat printing plate reposing on the upper surface of the platen II for the purpose of compelling movement of the plate with the platen I I during the working stroke.

Mounted above the platen I I on rigid side frame members I6 and I1 is a plate processin assembly, the same being shown in greater detail in Fig. 3. Included in the plate processing assembly as subassem'blies thereof are a smooth-roll, plate-treating sub-assembly designated generally by the numeral I8, a dentated-roll, plate-solidifying subassembly designated generally by the numeral I9, and a plate shaving sub-assembly designated generally by the numeral 20.

The smooth-roll plate-treating sub-assembly I8 is intended primarily for acting upon a printing plate through the medium of so-called face or back mats to bring about alteration of the level of local areas of the printing face of a printing plate in a manner to be more fully described hereinafter. The principal element of sub-assembly I8 is a smooth, rigid, cylindrical roll 2| mounted at its ends for free rotation in bearings 22 and 23, one of which is shown in detail in Fig. '7. Bearings 22 and 23 are carried in turn in eccentric bearing capsules 24 and 25, arranged to be angularly shifted to raise and lower the treating roll 2|. Eccentric bearing capsules 24 and 25 are closely fitted for limited angular adjustment within cylindrical seats formed in the side frame members I6 and IT. Secured to the eccentrio bearing capsule 24 and 25 respectively, are radius arm 26 and 2'I.

As appears more clearly in Fig. 8 radius arm 26 is pivotally joined at its outer end to a con necting link 28 which in turn is pivotally connected to radius arm 29 which forms a part of a bell crank assembly, made up of the arm 29 and a hand lever 38 both secured to a bell crank shaft 3|. The shaft 3| extends through bearing 32 in side frame I6 horizontally across the machine to and through a similar bearing in side frame member I? where it carries a crank arm 23 securely held in place thereon. Crank arm 33 is disposed in angular alignment with arm 29 and is pivotally connected with a link 35 which is pivotally joined in turn with the end of radius arm 2'5. Rotation of the shaft 3| forming a part of the bell crank assembly by manipulation of hand lever 30 causes simultaneous rotation of eccentric bearing capsules 2 5 and 25 with an attendant raising and lowering of roll 2 I.

As appears from the drawings, the eccentricity of capsules 25 and 25 is such that roll 2| occupies a lower position when the parts are in the position shown in the drawings. In this position link 23 and arm 29 on the one hand and link 3d and arm 33 on the other hand are respectively in alignment and thus through a toggle effect securely hold the capsules 24 and 25 against rotation with little torque being applied to the bell crank assembly. A detent pin 35 s-lideably held in a projection of arm 29, engages a recess not shown, beneath the same in side frame IS the same being adequate to maintain the roll 2| in lowered position even though very heavy upward forces are applied thereto. On the other hand, when it is desired to raise the roll 2| the same may be quickly accomplished by withdrawing the detent 35 and moving the hand lever 3|] to the broken line position indicated in Fig. 8, whereupon the detent 35 may engage the recess 36 to hold the roll 2| in raised position. In this way the roll 2| may be quickly released and raised or quickly lowered and locked in a precisely determined lowered position.

As pointed out above, the smooth roll 2| may be employed for the purpose of so-called treatment of a plate to bring about alteration in the levels of the printing face thereof. This may be accomplished as illustrated in Fig. 5 by placing a previously flattened and precisely machined printing plate B'I upon the platen I I having first placed in contact with the printing face of the plate a so-called face mat 38. There may also be placed in contact with the back of plate 37 a back mat 39 having open portions opposite the face mat 38. The mats 38 and 39 are formed in known manner from paper or other material of predetermined thickness and may be employed in single or multiple layers to obtain a thickness desired. If desired the back mat may be protected in known manner by a thin sheet metal position and there held and the platen H .is-

adjusted vertically by means of hand wheel l4 to a position where the spacing between the roll 2| and the platen I! is approximately equal to they thickness of the plate 31. With the parts thus adjusted control lever is then moved into feed ing position and the carriage 4 is caused to move from its extreme right hand position toward the left. In so moving the plate 31, as appears at the right in Fig. 5, is brought beneath th roll 2| as appears more clearly in the center portion of Fig. with a resulting downward displacement of the printing face of the plate 31 opposite the portions covered by the mat 39 and a reswlting upward displacement of the printing face of the plate 31 in the portions opposite the mat 3B. In this way the printing face of the plate 31 is caused to assume, in predetermined local areas, predetermined alterations in level. This alteration in the level of predetermined areas of the printing face is availed of subsequently in producing desired printing effects.

In so acting upon the plate 31 the roll 2i pro duces a deformation of the metal contained in the plate. This deformation gives rise to a socalled cold worked condition in the metal which momentarily for a mere matter of seconds leaves the plate in a more easily machined condition. The back of the plate 31 after embedment cf the back mat 39 is no longer fiat and in order that the plate be precisely and solidly held in a press it is necessary to return the back surface of the plate 31 to a plane condition. In accordance with this invention the correction of the back surface of the plate 31 is accomplished by shaving the same immediately following, within a matter of seconds, the treatment applied by the roll 2 l.

Shaving of the plate 3 1'is performed by the shaving sub-assembly 2|] previously referred to.

Shaving assembly 25 is made up, as appears more clearly in Fig. 3, of a horizontally disposed knife supporting beam 4|] rigidly secured to side frame members I6 and IT. The forward face of beam 45 is inclined as shown to provide a firm backing for an angularly disposed shaving knife 4| held firmly in place by a plurality of spaced anchoring bolts 42, one of which is shown in Fig. 3. Anchoring bolts 42 pass through openings 53 in the beam 40 which openings 43 are slightly larger in diameter than the bolts 42 thus providing a limited scope for vertical adjustment of knife 4|.

To provide a means for precisely positioning the knife 4| and to ensure its maintenance in fixed position, a shoulder block 44 is securely affixed to the beam 45 above the knife 4|. Extending through the shoulder block 54 in threaded engagement therewith is a plurality of horizontally ranged adjusting screws, one of which is shown at 45, the same being positioned to bear upon the upper edge of the knife 4|. Adjusting screws 45 are each provided with lock nuts 45 for holding the screws in predetermined position once an adjusted position for the knife 4| has been achieved. 7

Knife 4| is preferably adjusted to and held in a position slightly closer to the platen than the spacing between roll 2| and the platen this difference in spacing being equivalent to the optimum thickness of a shaving which may be removed by the knife 4|. If desired roll 2| may of course also be arranged to approach the platen II more closely than the knife 4|, in cases where for any reason it is desired to avoid shaving a plate which is subjectedto treatment by roll 2|. In cases where a back mat such as 39 and a metal protecting sheet are employed and it is desired to avoid damage to the same upon approach to the knife 4| and mat 39 and protecting sheet may be lifted as indicated in Fig. 5, and drawn upwardly behind roll 2| immediately following application of pressure by the roll 2|.

As a part of the shaving assembly 2|], and for the purpose of steadying a plate 31 while being subjected to shaving, a series of spring pressed rollers 41 are arranged beneath the beam 40, so as to bear upon the plate 31 with a steadying pressure insufficient to cause deformation of the plate 31.

Where the object to be accomplished is the straightening or solidification of a printing plate rather than so-called treatment of the same, the plate is first approximately dimensioned by roughing and shaving in its unstraightened and unsolidified condition, using therefor apparatus well known in the art. The approximately dimensioned plate is then placed upon the platen while at the right end appropriate adjustments are made to bring into operation the solidifying and straightening assembly l9.

The solidifying and straightening assembly I9 derives its support from side frame members It and i1 and from a stationary box beam 48 extending between said side frame members, rigidly secured thereto by screws 45 as shown. Surrounding box beam 48 and vertically slideable with respect thereto is a transverse roller supporting yoke made up of a top plate 5|), screw fastened to a pair of downwardly extending side shell members 5| and 52. The inner faces of side shell members 5| and 52 are precisely dimensioned at 53 and 54 respectively to bear with a close sliding fit against the sides of the box beam 48, and similarly at 55 and 56 to bear with a close sliding fit against the side faces of inwardly projecting bosses 51 and 58 formed respectively as integral extensions of side frame members It and I1. In this way the roller supporting yoke is closely held against tilting while at the same time limited free vertical movement is permitted.

Securely attached to the side shell members 5| and 52 near their ends and beneath the same is a pair of bearing hangers 59 and 55. Mounted for free rotation within the bearing hangers 59 and 60 is a dentated solidifying roll 6| the surface of which is uniformly covered with a pattern of pyramidal projections as shown in greater detail in Fig. 9 Also held between the side shell members 5| and 52 by fastening means not shown is a bottom plate 52 which serves to render the roller support yoke a roughly rectangular shell surrounding the box beam 48. Between the top of the box beam 48 and the top plate 58, in recesses provided therefor are three expansion springs 63 the tension of which is sufficient to more than support the entire weight of the roller supporting yoke and associated parts thus causing this assembly to be translated upwardly in the absence of downwardly acting force.

The bottom plate 62 is provided with upwardly facing inclined lands 64 which are integrally formed as a part thereof. Between the bottom plate 62 and the bottom of box beam 48 there is provided a horizontally slideable wedge member 65 having inclined faces of a pitch corresponding with that of the inclined lands fi l with the result that when wedge member 65 is moved toward the left as depicted in Fig. 6 roller GI and its supporting yoke is forced downwardly against the action of the springs 63.

For the purpose of controlling the lateral position of wedge member 65, a nut 66 received within a slot in the wedge member 55 is arranged to threadingly engage a screw shaft 61 which in turn is mounted for rotation in a bearing 68 carried in the boss The outer end of shaft 6? carries an adjusting hand wheel 68 arranged exterior to outboard bearing 69 and micrometer indicating mechanism 10. In this way rotation of the hand wheel 68 causes vertical adjusting movement to take place in roll 6|. By reason of the extensive area of engagement between wedge member 65, the yoke assembly on one hand and the bottom of box beam 48 on the other hand, the roller BI is very rigidly held against upward displacement in any position of adjustment.

Between the bearing hangers 5S and 60, side shell members 5! and 52 are extended downwardly to form supports for spring pressed steadying rolls H and 12 which are arranged to bear with a light but steadying pressure against a plate 3'1 carried on the platen i i.

In acting upon an approximately dimensioned printing plate 37 with the solidifying sub-assembly l9, platen II is first vertically adjusted through manipulation of hand wheel M to cause the plate 31 to assume a position in which the same will be subjected to shaving to an appropriate degree b the knife 4|. To facilitate such adjustment micrometer indicating means '13 is associated with adjusting screw i3. Having brought about adjustment of the platen ii for the degree of shaving desired hand wheel 68 is then manipulated to cause the roll 6! to assume a position of predetermined distance below the top level of plate 31. With this adjustment, platen H is caused to move toward the left in Fig. 1 and the plate 31 is caused to pass beneath the roll El and the knife 4: becoming acted upon in a manner diagrammatically indicated in Fig. 4.

As indicated, toward the right in Fig. 4 the plate 31 when placed upon the platen H may be possessed of inaccuracies in the plane of the printing face as indicated at M as well as areas of deficient density as indicated at 15. The plate 3'! having passed beneath the roll 6| as indicated in the central portion of Fig. 4 is caused by pressure induced deformation of the metal of the plate to be brought to a condition where the printing face of the plate is corrected and the areas of reduced density are compacted. In so doing the metal composing the plate 31' and particularly a layer of the same directl beneath the roll Bl, as indicated by stippling and the numeral I6, is rendered momentarily more easily cut and machined. Thereafter the plate 3'! moves with little lapse of time directly into contact with the knife 4! which acts to remove a very precisely cut surface shaving as indicated at the left in Fig. 4. When a plate such as 3! is shaved as explained above immediately following pressure deformation and before aging of the cold worked condition metal sets in to an appreciable degree, the stresses created in the plate due to the shaving action are much reduced with the result that deformation of the plate due to the shaving action is minimized.

This is in contrast to the action which occursv when a plate is shaved without taking advantage of the momentary increased machinability produced by cold working under which circumstances the stresses created in the plate due to the shaving action at times causes lifting of local areas of the type face of the plate with the result that the desired precisely positioned relationship of the type face to the back of the plate is not obtained.

From the foregoing it may be observed that the apparatus and method of this invention may be employed for the solidification and straightening of an approximately dimensioned printin plate and for the simultaneous shaving of the same to produce a plate of increased dimensional accuracy not heretofore obtainable with apparatus and methods heretofore employed. If desired the apparatus and method of this invention may likewise be employed for the simultaneously treating and shaving of a plate to bring about a predetermined arrangement of levels of local areas of the type face with relationship to the back of the plate. It will be un derstood, however, that a printing plate ordinarily is to be acted upon alternatively by one or the other of the foregoing actions. When a plate is to be subjected to solidification and straightening the roll 5! is lowered and roll 2! is raised to inactive position. On the other hand, if a plate is to be subjected to treatment by roll 2! the latter is lowered and roll 6! is raised to inactive position. Under some exceptional circumstances conditions may arise where rolls 2| and GI' may both be lowered to active position and the plate 37 may be subjected successively to the action of both rolls and then immediately shaved.

We claim:

1. The method of acting on a printing plate formed of a metal alloy containing a predominant proportion of lead for the purpose of establishing a predetermined dimensional relationship between the printing face and the back of the plate which consists in placing the printing face of the plate in contact with a rigid nondeformable supporting surface having a predetermined contour coincident with the printing face contour desired, progressively applying rolling pressure to the back of said plate to be acted upon in amount sufficient to cause permanent deformation of the metal alloy in said plate with displacement of the printing face of said plate into conformity with the contour of said supporting surface, said rolling pressure also being in amount sufficient to establish a coldwork induced temporary increase machinability of said metal alloy, and then while said printing face remains in contact with said supporting surface and while said temporary increased machinability persists immediately shaving the back of said plate to a surface having a predetermined dimensional relationship to the printing face of said plate.

2. The method of acting upon a printing plate in accordance with claim 1 wherein the nondeformable supporting surface is a plane surface and wherein the rolling pressure is applied in a pattern of closely spaced discontinuous areas whereby the printing plate is straightened and solidified.

3. The method of acting upon a printing plate in accordance with claim 1 wherein the nondeformable supporting surface is provided with .DONALD C. COTTRELL.

CARL C. SWEET.

References Cited in the, file of this patent UNITED STATES PATENTS Number Name Date McKee Apr. 4, 1911 Number 10 Name Date Droitcour Oct. 10, 1911 McKee Nov, 4, 1913 Erickson Feb. 17, 1925 Claybourn Aug. 11, 1925 Claybourn Nov. 16, 1926 Erickson Feb. 8, 1927 Claybourn Mar. 27, 1928

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