US2619904A - Plate straining mechanism for use in printing machines - Google Patents

Description

1952 M. MOSEGAARD 2,619,904

PLATE STRAINING MECHANISM FOR USE IN PRINTING MACHINES Filed May 14, 1947 s Sheets-Sheet 1 pvvewron ATToR'NEY.

Dec. 2, 1952 M. MOSEGAARD PLATEv STRAINING MECHANISM FOR USE IN PRINTING MACHINES I 3 Sheets-Sheet 2 Filed May 14, 1947 M 6 M M 3 6%.. m M 6 0 0 8 4. 4 M. 4 w 5 A TTORNE Y Dec. 2, 1952 M. MOSEGAARD 2,619,904

PLATE STRAINING MECHANISM FOR usa IN PRINTING MACHINES Filed May 14, 1947 s Sheet s-Sheet 5 INVENTOK.

v ATTORNEY.

Patented Dec. 2, 1952 PLATE STRAIN'INGMECHANISM FOR USE' IN PRIN'T-ING MACHINES -Marius .Mosegaard,-Copenhagen, Denmark, as-

signor to R. ,Hoe-& 00., Inc,, New Ycrk,.N. Y., a corporation of New York Application Mayl l, 1947,'Seria1 No. 747,912

1 :lniD'e'nmark Mayx2.0,:1946

zstoiaimsl. c1. 1(1141'5;1)

lhisf-invention relates to "mechanism for the straining of-a printing lplate around the plate cylinder tof=agprinting machinaespecially in high speed rotary presses for ;planographi c and particularly for .oiT-set printing; the invention is concerned with an. arrangement tin which the ends-ofthe printing, plate :are secured to clamp- :ing 'bars which :are gpassedinto a slot on the cylinder and to which pressure is applied to strain theplate around thecylinder.

The --'known:mechanism .hasnroved unsatisfactory, especially in its: applicationto machines in which the whole ,periphery of .the cylinderiisito hesutilised, the cylinderhaving :only. a slotiwhich admits the :two barsnsecured to the two :ends :of the printing plate. Such mechanisms. havejbeen so :arranged as to :impart 2a.;radial andinwardly directed pressure on :the bars, the ends of :the plate being bent inwards overlrounded edges sat the opening -of the slot. These edges are thus subjected-to considerable wear, the printing-plate sliding over these Sedgesxduring the plates fitting and straining; this :is especially the :case when theplate is made .of :a relatively :hard andzstiff material; -as for :instance .rustless ior stainless steel.

Another-disadvantage with this .known sconstruction is that .the opening for i'mouth :of .zth'e' slot, between the *ends of the'rplate passinglov er the rounded edges, has .to be filled with Ca .zbar the exteriorzsurface of which;is at.the same level as the periphery .of 'the;.plate cylinder; however with :thewearingwoi "the rounded edges," this bar passes too far into the :slot sso producing on the surface iofth'e cylinder atrecess which may accumulate liquid during the printing :and-also set up hammer orzshock in the working of the press.

According to this ,invention the ends of "the plate have secured to theirunder surface'sclamping bars the plate engaging faces of which when in position form substantially :a continuation of the periphery .of the ."cylinder; these bars which when in position extend below the circumference of *the cylinder are movable relatively towards oneanother about the cylinder so .as to draw the plate ends towards one another to strain the plate'about the'periphery of the cylinder.

This arrangement avoids the defects which arise from bending .theends of the plate about theclamping bars and lends itself to an arrange mentin-which either the one'end of vthe'plate can overlap the otherend when ;a continuous printing surface is required or the two endstcan be brought extremelyclose together iforithesame reason. l/ioreover of course-the endszof thetplate are supported at the circumferential .levellonthe cylinder bythe bars.

Other characteristics of the invention will he described hereinafter with reference to-the draw-- ings, of which Figure 1 isanvend ,view of-atheicylinder of a rotary printing machine having in its periphery one slot containing a mechanism .according to the invention. Figure 2 (is aslocalisec- \tional elevation :taken on the line IIQII ure 1.

Figures -3 and 4 [show on .an enlarged 'scalema cross-section of thecylinder at theregion ofethe slot in which thestraining mechanism :is {arranged; the two figures showing the mechanism respectively in non-straining and strained state.

Figure 5 shows a portion of the mechanism-in perspective some of the parts bein cutaway in order .toprovide .greater clearness. Figure MG/isle local sectional view of amodification. figure 37 is a longitudinalisection takenthrough oneihalf of the length of the cylinder and .oftherai-l and having certain parts mounted thereon the plate also being indicatedin the f gureand Figure Sis a plan viewof therail and parts mounted thereon as .shownin. -Figure 7,; Figure 9 isa plan view of one .halfvlength .of .the whole mechanism according to the invention withdrawn from the cylinder.

As appears. from. Figures l-5, an .axialslotMiis formed in the periphery of .the platecylinder Ill having at the ends a shaft .12. :On theperipheral surface of the cylinder it islaid .a printing plate l 6 of .a convenient metal, for instancews'tainless steel. The under surface of the endsiof .thisplate are respectively spot welded to one face-of two clamping bars i8 and .20 accommodated .in the slot 14 and thesebars are. moved-towardsone another .to effect the straining of the plate .by means of the mechanism of the invention, that mechanism bein .also mounted in the-slot vM.

As illustratedtheface of the upper side oi-the bars 5'8 and at '(to which iace the ;plate is,se-

cured) forms substantially .a .continuation of .the circumference of the cylinder It; .inthevarrangement shown inFigures land 2..that -end ;of-the plate which is secured .tothe ,bar [Elba-s aits'zfix tremity at or within the lateral-surface .of the bar .18 which is opposed to tthe'bariil. In.. the case of the end securedto the barZll, the-.edgeiolf the plate extends beyond the corresponding .:la;teral surface, so thatthe end borders-,ofthesplate, after the straining operation, extend over -one another slightly.

In Figure 6, both ends of the plate terminate at or within the :opposediaces :of the two ba rs bars I3, 20 afford a support over the slot I4 for the ends of the plate at substantially the circumferential level of the periphery of the cylinder.

Referring now to the straining mechanism itself, at the base of the slot I4 is a bar 22 which is secured to the cylinder I 6 in a convenient way, for instance by means of screws, not shown.

Screwed into the bar 22 is a series of screws 24, the axes of which lie in the axial central plane of the slot, and the heads of the screws are formed with two flanges 26 and 28 providing an intermediate neck 30, see Figures 3-5. A square recess or hole 32 is provided in the screws to receive a key to turn the screws.

The slot I4 is recessed back from the opening so providing two sloping undercut surfaces 34, Figures 3, and 4, lying relatively near the circumference of the cylinder I6. In the slot I4 are provided under the sloping surfaces 34, wedge pieces 36 having outer faces formed to the same angle as that of the sloping surfaces 34. These wedge pieces are of angle of L form having the one limb extending up the radially directed side of the slot I4, and the other limb is formed to sit around the neck 36 of the screw 24, between the flanges 26 and 28.

A number of these wedge pieces is provided at both sides of the slot I4 these various pieces being independently adjustable. The wedge pieces at both sides are staggered as seen in Figures 8 and 9 for which reason the wedge piece shown at the left of Figures 3 and 4 appears in section while that shown to the right lies behind the plane of the section, each wedge piece 36 having its own screw 24. The limb of each wedge piece which seats about the screw neck 30 has an extension 38, see Figures 5, 7 and 8 and having an opening to receive the neck and is of such size as to allowa certain displacement of the wedge piece 36 longitudinally to slot l4. A recess 40 in each wedge piece 36 is provided to accommodate or clear a portion of the flange 26 during the straining operation which involves a shifting of the wedge pieces.

Between the consecutive wedge pieces 36 are arranged guide blocks 42 these blocks being screwed to the bar 22 by means of screws 44, see Figure 8. The upper portion of the blocks 42 has substantially the form of an isosceles triangle, the one leg having a recess 46 at right angles to the axial mid-plane of the slot, for a purpose to be described later. The consecutive blocks are secured respectively in reverse sense as shown in Figures 7 and 8.

On the opposed faces of the bars I8 and 26 grooves 48 (Figure 6) are formed to produce on the lower side of the bars, a rib or looking component 50 to enter the recesses 46 of the blocks 42. In order that the sloping faces of the guide blocks 42, which do not contain the grooves, 46 shall .not foul the bar inserted in this side, for example the bar in Figure 5, the bar 26 is notched at 52 in register with the said slanting sides or faces.

When the mechanism is not in plate-straining condition, as shown in Figure 3, the vertical faces of the wedge pieces 36 lie along the lateral walls of the slot I4, and the screws 24 are screwed to their limit into the bar 22. When the printing plate I6 is now laid round the plate cylinder ID, the bars I8 and 26 can be passed into the opening of the slot I4 into the position shown in Figure 3. The printing plate now lies loose round the plate cylinder its ends being free from one another.

To strain the printing plate I6 the screws 24 are screwed upwards by the key to engage in the recess 32 for the passage of which key excisions are made either at the ends of the plate or in the bars I6 and 20, as illustrated in Figures 5 and 9 where said excisions are designated 54. By screwing a screw 24 upwards, the corresponding wedge piece 36 will also be moved upwards and simultaneously it will be forced inwards of the slot I4 by the co-operation of its outer sloping face with the inclined surface 34 of the slot. When the wedge piece 36 has passed a small distance inwards from the position shown in Figure 3, it comes into contact with the opposed face of the bar I8 (or the bar 20) and thereafter in its continued movement it pushes the bar I8 (or the bar 20) in front of it and the rib 50 is caused to pass into the groove 46 in the associated block 42.

Obviously the bars I8, 26 will have a tendency to cant i. e. in the case of the bars I8 to turn in counterclockwise, since the printing plate I6 exerts at the top a pressure to the left, while the wedge piece 36, especially its upper end, exerts lower down a pressure to the right. This canting is however prevented by the co-operation of the rib 55 with the groove 46, whereby it is possible to produce a couple to oppose the turning couple. The moment of the couple tending to cant the bar becomes smaller as the wedge-piece 36 passes outwardly in the slot I4. It is convenient to construct the mechanism in such a manner that the outer faces of the wedge pieces 36 reach the printing plate I6 near the circum- 0 ference of the cylinder I6, when the opposed faces Figure 5 illustrates how the bars I8 and 20' pass beyond a block 42. Bar I8 (or 20) passes its tongue 56 into the slit 46 on one inclined side of a cross piece 42, while the notches 52 of the bar 26 (or of the bar I8) are clear of the other inclined side of the cross pieces 42 engaged by the bars I8 (or 26). The same figure illustrates two adjacent wedge pieces 36 on opposite sides of the bars I8 and 26. These wedge pieces, as before mentioned, lie in continuation. The front end of the wedge piece 36 at the right of the drawing, is cut away in order to make the associated bar 20 visible. As also appears from Figure 5 the wedge pieces 36 shown at the left of the figure have excisions 56 to clear the blocks 42. The horizontal limb of a wedge piece 36 occupies approximately the distance between two consecutive blocks 42.

In Figures 7-9 the chain dotted line at the right denotes the transverse centre line of the rail 22 and of the cylinder I6. There being one wedge piece 36 at the one or the other side of the rail 22 between each two consecutive blocks 42, see Figure 9, and there being one screw 24 for each wedge piece, there will be found in the direction of the ends of the rail 22 relatively more screws 24 for the adjustment of the wedge pieces 36 and consequentiy for the s'traifiing of the plate, than in the middle of the rail. IYI-iisis due to'the fact that at the ends a greater rerce i'snecessaryfor' thestraining. of the printing plate, and in addition with a row of screws there exists the possibility of adjusting the bars 1 8 and to be parallel with or inclined to the axial direction. 'The'twoends'of the plate may be adjusted independently, namely respectively with the screws 24-acting on wedge pieces 36 of one side of the-slot, and the-screws acting on the wedge pieces of the other side; thus with the mechanism according to the invention it is possible to obtain anexa'ct register in the adjustment of the printing plate relatively to the un- Her-lying cylinder surface. :It is possible not-only the-shift theprinting plate' a little forwards or backwards in tangential direction, but fs uch' an adjustment is alsorealisable so'that the extremitfs'of thelprintingplate lie eithe'r in a's'tfaight liife parallel with the axis of the cylinder or altingla :he'lix having a slight gradient in "the oneorthe other direction, a'featiire which is of considerable .practical value. Further, the mechanism according. to the invention involves that the printing plate can be mounted and strained very quickly on aplate cylinder.

It w-ill be seen that the distance between the blocks 42 diminishes from the middle of the cylinder to the end, with the exclusion of the two outer blocks which are placed with greater distance.

This greater spacing enables two wedge pieces 36 facing each other to be provided at the ends of the rail 22 (see Figure 9). Both these wedge pieces are placed between the two terminal blocks 42, and in the intermediate space between these there are two screws 24 for the adjustment of each particular Wedge piece.

The invention may be used whether or not the bars I3, 20 at the printing plate ends are accommodated in the same slot this depending on the extent to which the plate is required to extend around the plate cylinder; thus the invention can be applied to those planographic printing presses in which the printing plate only extends over, for instance, three-quarters of the surface of the circumference of the cylinder, while the remaining part of the cylinder is out of action during printing. While the invention is useful preferably for printing plates of hard and relatively stiff material, for instance rustless steel. it may also be employed in cases in which the printing plate consists of a softer ma terial, such as zinc, aluminium or copper.

What I claim is:

1. A cylinder, a printing plate having clamping bars attached to its under surface at its ends, the said bars extending within the periphery of the cylinder, independently operable straining components extending as a series longitudinally within the cylinder, the said straining components having wedge surfaces extending towards the periphery of the cylinder and co-operating with similar wedge surfaces formed in the cylinder, and radial screw means arranged to force said straining components outward towards the periphery of the cylinder and against the clamping bars to engage and then move at least one clamping bar towards the other clamping bar and strain the plate about the cylinder.

2. A cylinder, a printing plate haVing a clamping bar attached to its under surface at each of its ends, the said bars extending within the periphery of the cylinder and in combination, a

plurality of independently operable straining components having sloping "surfaces arranged to engage the clamping bar at one end of the plate, a plurality of similar straining components di'sposed to engage the clamping bar .at the other end of the plate, "and radial screw means tomove each of the straining. components individually outward and about the cylinder whereby the straining components are causedto engage the clamping bars fa'l'ld =dr'aw' them together to strain the plate about the "cylinder.

3. -'A cylin'de'r; and-apparatus tols'train a flexible' printing zpla'te about the cylinder, the 'said apparatus comprising two sets of straining com ponents disposed within the periphery rof the cylinder, one set being disposed to engagera clamping bar secured to one end --of"the Zplate and the other set being disposed -.to'-eng'age *a clamping bar secured to theother end of the plate and the straining componentsof one, set being arranged I in alternation with the straining components of the othersetJeach strainingycompcnent having a wedgesurfaceslidable against a relatively fixed wedge surface in the cylinder, and screw means acting in .a' direction radial to the cylinder and co -operating with the wedge surfaces to move thestr'ai-ning components in a direction oblique toradial andthereby draw-the :lamping'fbars together to strain-the plate.

4. In combination, a cylinder, a flexible printing plate having tensionin bars secured to its under surface at the longitudinal edges of the plate, independently operable straining components for each bar disposed in a longitudinal series in a sloping surfaced undercut recess in the cylinder, each straining component having a wedge surface formed to engage a sloping surface of the recess and radial screws operable by a tool inserted between the tensioning bars to move the various straining components individually and outwardly towards the periphery of the cylinder whereby each straining component is moved by wedge action into enga ement with a bar and then moves that bar towards the other bar to strain the plate about the cylinder.

5. In a printing cylinder for use with a flexible printing plate, a. longitudinal slot having a sloping undercut wall, a clamping bar secured to one edge of the printing plate, a guide block fixed in the slot and having a sloping surface parallel with the sloping wall, a wedge piece formed with opposite parallel surfaces arranged to engage the sloping wall of the slot and the sloping surface of the guide block and having another surface arranged to engage the clamping bar, and a screw adjusting means operable to move the wedge piece between the parallel surfaces to effect movement of the clampin bar peripherally of the cylinder.

6. In a printing cylinder for use with a flexible printing plate, a longitudinal slot having a sloping undercut wall, a clamping bar secured to one edge of the printnig plate and having a rib, a guide block fixed in the slot and having a groove arranged to interlock with the rib and a sloping surface parallel with the sloping wall, a wedge piece formed with opposite parallel surfaces arranged to engage the sloping wall of the slot and the sloping surface of the guide block and having another surface arranged to engage the clamping bar, and a screw adjusting means operable to move the wedge piece between the parallel surfaces to effect interlocking of the groove and the rib, and cause movement of the clamping bar peripherally of the cylinder,

7. In a printing cylinder for use with a flexible printing plate, a longitudinal slot having opposed sloping undercut walls, clamping bars secured to opposite edges of the printing plate and each having a rib, a plurality of guide blocks fixed in the slot each having a groove arranged to interlock with a rib and a sloping surface parallel with a sloping wall, a plurality of wedge pieces formed with opposite parallel surfaces arranged to engage the sloping .walls of the slot and the sloping surfaces of the guide blocks and'each havin another surface arranged to engage a clamping bar, and a plurality of screw adjusting means operable to move the wedge pieces between the parallel surfaces to effect interlocking of the grooves with the ribs, and cause movementof the clamping bars peripherally of the cylinder in opposite directions.

8. A printing cylinder having an axially extending slot in its periphery, and means to strain a flexible printing plate about the cylinder, including a pair of clamping bars flush with the peripheral surface of the cylinder and movable transversely in the slot, one bar being secured to each end of the plate, two sets of independently operable straining components located in the-slot, within the periphery of the cylinder and aligned axially thereof, each set being disposed to engage a clamping bar, the straining compo- 8 nentsof oneset being. arranged in alternation with :the straining components ,of the other set. and radial;screwg means-arranged to move the straining components of each' set individually, anddraw the clamping bars and the ends ofthe plate together at the periphery ,of the cylinder.

MARIUS MOSEGAARD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 838,790 Kneppler Dec. 18, 1906 1,049,195 Banzett Dec. 31, 1912 1,531,124 Murray Mar. 24, 1925 1,545,791 Owen July 14, 1925 1,582,390 Evans Apr. 27, 1926 1,827,300 Pritchard Oct. 13, 1931 2,033,205 Poppe Mar. 10, 1936 2,180,732 Durham Nov. 21, 1939 2,194,424 .Grupe Mar. 19, 1940 2,406,883 Leuhrs Sept. 3, 1946 FOREIGN PATENTS Number Country Date 617,936 Germany Aug. 30, 1935

Images