US2577099A

US2577099A - Method of and means for registering impressions in multiunit sheet printing machines

Info

Publication number: US2577099A
Application number: US676733A
Authority: US
Inventors: Alexander J Albrecht
Original assignee: R Hoe and Co Inc
Current assignee: R Hoe and Co Inc
Priority date: 1946-06-14
Filing date: 1946-06-14
Publication date: 1951-12-04
Anticipated expiration: 1968-12-04

Description

A. J. ALBRECHT Dec. 4, 1951 2,577,099

I METHOD OF AND MEANS FOR REGISTERING IMPRESSIONS IN MULTIUNIT SHEET PRINTING MACHINES Filed June 14, 1946 6 Sheets-Sheet l In A" C I F n B n I. n 5 D i llllllklil m I u J n F u u c J -i mir--- A y I- f B i I I w a c T511! 4 I Alexander J. Mm

INVENTOR ATT . ALBRECHT Dec. 4, 1951 A, 2,577,099

METHOD OF AND M AN 0R REGISTERING IMPRESSIONS IN MULTIUNIT SHEET PRINTING MACHINES 6 Sheets-Sheet 3 .Alexandar J Albrecht INVENTOR Filed June 14, 1946 Dec. 4, 1951 J; ALBRECHT 2,577,099 METHOD OF AND MEANS FOR REG TERING IMPRESSIONS IN MULTIUNIT SHEET PRI NG MACHINES Filed June 14, 1946 6 Sheets-Sheet 4 Alexander J Albrecht INVENTOR BY W ATTORNEYS Dec. 4, 1951 ALBRECHT 2,577,099

SSIONS IN METHOD OF AND MEANS FOR REGISTERING IMPRE MULTIUNIT SHEET PRINTING MACHINES 6 Sheets-Sheet 5 Filed June 14, 1946 .D N R I I I l I III I K Dec. 4, 1951 A. J. ALBRECHT 2,577,099

METHOD OF AND MEANS FOR REGISTERING IMPRESSIONS IN MULTIUNIT SHEET PRINTING MACHINES 6 Sheets-Sheet 6 Filed June 14, 1946 Alexander J Albrecht mmvron A rramvzrs sheets against the successive cylinders of the Patented Dec. 4, 1951 UNITED STATES PATENT OFFICE-;:

ME'rnon or AND MEANS Fort REGISTERING IMPRESSIONS IN MULTIUNIT sues-r PRINTING MACHINES Alexander J. Albrecht, West New York, N. 1., as-

signor to R. Hoe 8; (30., Inc., New York, N. Y., a corporation of New York Application June 14, 1946, Serial No.'676,733

1 29 Claims. (Cl. 101-183) 2 v v The present invention relates to sheet fed mulas distort the trailing edge thereof for correcttiple unit rotary printing machines and more paring registry of the impressions thereon without ticularly to the gripping mechanism for the substantially aifectingregistry of the impressions sheets being fed through the press and to methon the leading edge of the sheet.

ods of correcting registry. 5 A further purpose of this invention is to pro.-

In printing machines of this type the sheets are vide means for bowing or bending the gripper bar fed from one unit of the press to the succeeding mechanism by which the sheetis held in such a unit, an impression being made thereon by each way as to warp the sheet and bring its trailing unit. All these impressions must be in register. edge back into registry without affecting the lead- Grippin devices, usually mounted upon a gripper ing edge of the sheet. V bar mechanism, are employed for holding the Another object of the invention is the provision of means for controlling the degree of bowing of press and are so constructed and arranged as to the gripper bars at the individual cylinders of the provide for proper axial and peripheral alignpress, since it has been found that correction is ment of the sheet with the cylinders for insuring most necessary at the third and any following register. Several forms of this arrangement are units, the paper having been warped out of shape in use, and two of these are fully described and j during its passage through the earlier illustrated in Patents Nos. 2,138,405 and 2,100,852 Another object is the provision of simple, inexwhich describe a conveyor type press anda trans j pensive and easily. installed [mechanism for fer cylinder type press, respectively. I achieving the above purposes, which may be sim- It has been found that the sheets, while going ply and quickly adjuste by the operator when through the various units of the press, will fredesirable, and which-wil quently warp or distort, especially at the trailing preventing sh etsthat-hav b end, due to the effect of atmospheric and. press v conditions, together with the mangling action-of, s I I the cylinders between which the sheet passes p s I or objects in view, as may Such effects are most noticeable'in offset presses,-.g appear from the accompanying specification, the in which the water used has a tendency to, hu invention; consists in the method of operation, midify the sheets and expand their trailing edges; combinations of parts nd features of construc- The leading or forward end of the sheet, where it; tion which will be firs ascribed. in connection is clutched by the gripping fingers, is usually not' 3Q with-the accompanyingdrawing', showing gripper materially afiected but the trailing end will, bar .,be'nding mecha; s embodying the invenspread laterally or perhaps shrink, dueto mois-'' tion 'i'n two preferred orms, andthe'method and ture and other conditions. In presses where features forming the. invention will then be speheating, air drying and the like devices are uti- Y Y "cifically pointedfoutin theclaims; lized between units, further distortion eifectsmay' occur. As a result, although the later impres- I ,Figure '1 aadi sions will be in register at the leading or forward tive action upon end of the sheet, as well as down the center of the i embodying the pr en sheet, those at the rearward or trailing end of the I sheet, especially toward the margins thereof, will FiguIe-Zfisa simila iagram to Figure 1, but in be out of register. The amount'of such distortion which the sheet has en shrunk at its'lower end is small but in such work it is necessary that it be during its passagef'through the press; corrected. Figure 3 is a diagrammatic view of a chain con- It has also been found that under certain conveyor type of multiple unit press in which the ditions, piled sheets will sometimes absorb moispresent invention may be embodied; ture which expands one or more of the edges of Figure 4 is a longitudinal section through a each sheet, causing a fullness or slight ruflling cylinder of the press shown in Figure '3, showing at the edge, and when such sheets pass between the gripper bar mechanism embodying the presthe cylinders of the printing machine, there is a cut invention; 0 considerable tendency for this fullness to become Figure 5 is a sectional viewv on the line 5.5 of localized alldPlOduCe one or more wrinkles in the Figure 4; sheet. This condition can be overcome by the Figure 6 is a sectional view on the line 6-6 of means herein disclosed. Figure 4;

A purpose of the present invention is to pro- Figure '7 is an end view of-the cylinder illusvide a method of warping a sheet in such a way ,trated in Figure 4; v

illustrating the correctpassing through a press vention, which sheet has previously spread atfi'ts ower end;

alsofprovide means for Figure 3 is a diagrammatic viewillustrating the operation of the present invention;

Figure 9 is a diagrammatic view of a transfer cylinder multiple unit press invention may be embodied,

Figure 10 is a top plan view of an impression cylinder of the type employed in the press illustrated in Figure 9, embodying the present invention;

Figure 11 is an end view of the impression cylinder illustrated in Figure 10, with a portion broken away;

Figure 12 is a sectional view on the line lI-il of Figure 10; v

Figure 13 is a sectional view on the line lI-II of Figure 11; and

Figures 14 and 15 are, respectively, similar to Figure 7 and a portion of Figure 4 and show a modiiled form of theinvention.

Figures 1 and 2 are diagram provided to illustrate the method of correcting register embodied in the present invention. As previously stated, a sheet, after passing through one or more units of a multiple unit sheet fed press, is affected by atmospheric conditions and becomes distorted. In some presses, this is due to the excessive moisture inherent in the method of printing used. as in oflsetpresses. The mangling action of the cylinders between which the sheets pass, together with temperature variations, may also cause some distortion of the sheets.

Referring to Figure 1, the sheet A has been previously distorted. its trailing edge having been spread as indicated in solid lines, whereas the leading edge B, which is gripped by the gripping mechanism C of the press, remains unaffected. The usual mechanism provided for grippin the sheet in proper position to ensure registry will control its position sufliciently to keep the printing on the upper or leading end in registry, and the printing through the center of the sheet will also remain in register. However, at the sides of the lower edge of the sheet the registry is affected. The primary impressions, indicated by the broken lines D, will spread as the paper itself stretches. Thus, the impression made by the succeeding unit (say, the third or any later unit of a multiple color press) will be in register at the top of the sheet and through its center, but will be out of register at the sides of the trailin lower end of the sheet. By pulling the center of the sheet forward at its center, as shown by the dotted lines E, the leading edge of the sheet 'is bent in the tangent plane common to both cylinders at the impression line or point and is warped as it passes through the printing couple, its side edges near the trailing edge being drawn toward the center and the impression indicated by the line D will be simultaneously drawn toward the center'to become parallel to the center line as indicated at F and thus register with the impression made by the succeeding unit.

Figure 2 illustrates themethod as applied to a sheet which has shrunk at its lower end. as indicated in solid lines. The impression thereon, indicated by the broken lines D, would be out of register at the sides toward the lower end of the sheet. By pushing the leading edge of the sheet backward at its center or advancing its edges. as at E, the trailing end of the sheet will be caused to spread as it goes through the printing couple, whereupon the printing thereon resumes its correct position parallel to the center line and in register with the succeeding impression, as indicated by the dotted line F. x

in which the present tions).

In both of the figures the dotted outline I represents the sheet after it has been warped back into its original shape. It is to be understood that the degree of distortion is quite small and has been exaggerated for purposes of illustration, but in high grade printing work even a very slight lack of register is undesirable. Only a slight warping of the leading edge of the sheet. as obtained through a slight shifting of the position of the gripping mechanism at the center, is necessary-to make the correction.

This method of correcting register where sheets have become distorted during the printing process is applicable to any type of automatic sheet fed multiple unit press. Means for carrying out the method are discussed below with reference to conveyor type presses and transfercylinder type presses, in both of which the sheets are held by gripp g fingers as they are carried through the press and about the impression cylinders;

In Figure 3 is illustrated a multiple color ofi'set type press embodying a chain conveyor I for carrying the sheets from the sheet feeding unit 2 and registering unit is through the various printing units 3 of the press. Three such printing units are shown, but it will be understood that any desired number may be employed. Attached to the chain conveyor l are gripper bar units 4, each of which comprises a telescopic tubular bar 5 to which is afilxed a number of grippers 6 (Figures 4, 5 and 6). The construction of the gripper bar and its attached grippers is described in Patents Nos. 2,231,914 and 2,286,032, together with its operation and integration in a printing machine of the type in question.

The ends of the telescopic bar I are held in carrying members ll (see Figure 4) which are attached to the conveyor chain l. The conveyor chain (as described in the above-mentioned patent) cooperates with sprocket teeth ii formed on a projection of the end plate of the impression cylinder [2. A roller II is also carried by each carrying member Ill, and cooperates with a cam or track member it attached to the frame of the press and following the contour of the cylinder ii, for pressing the bar 4 downward within a channel 20. The channel 20 is formed in the body of the cylinder I! for receiving the gripper bar 4 as it is carried by the chain i over the cylinder. The roller i5 and cooperating track l6 act to force the carrying member In and its associated gripper bar 4 into the channel Ill toward the axis of the cylinder II, as the chain conveyor I travels over the sprocket teeth ll of the rotating cylinder.

It is to be understood that the structure thus far described is duplicated at either side of the press and at either end of the cylinder i2, although only one end has been illustrated in the drawings.

The gripper bar 4, being of considerable length as compared with its diameter, is supported upon sets of rollers located in the channel 20, to prevent its sagging toward the center of the cylinder. In the present construction, these rollers are carried by rods running longitudinally withinv the channel 20 and supported by hearing blocks 30, Ill attached to the bottom of the channel 20, as illustrated in Figures 4-6. The rollers 3| are carried by a shaft or rod 32 (left hand side of illustra- This shaft 32 is held in the bearing blocks 30 and It in any suitable manner and may, if desired, terminate in one end of the cylinder 12.

The second set of rollers, 33, are can-led by an eccentric rod or crank shaft 34, which is formed.

3 in three sections. The first section is journaled in one end of the cylinder l2, extending therethrough. and extends toward the center of the cylinder to the first bearing block 30, in which it is also journaled. Inwardly of this block 30, the

shaft or rodis of a reduced diameter, with its cen- 7 portion of the rod; This reduced diameter eccentric portion 34' of the rod 34 extends along .the channel to the second bearing block 30',

at which point the eccentric ends and the extension of the rod, of lesser diameter than the I eccentric portion, has its center in alignment with the center or axisof the firstp rtion, thus,

pairs of rollers are preferably located approximately one-third of the distance in from the ends of the cylinder I2, for supportingthe gripper bar'4.'

The rod 34, extending through the end of the cylinder I2, has a sector plate 40 keyed to its outer end for rotary movement therewith. The plate 40 has an arcuate slot 4I formed therein through which a bolt 42 is inserted for threaded insertion into the adjacent end plate of the cylinder I2. By loosening the bolt 42, the plate 40 may be rotated as permitted by the arc of the slot 4|, thus rotating the shaft 34 and consequent- 1y swinging the eccentric portion thereof on which the rollers 23 are mounted.

Figure 8 shows diagrammatically the effect of adjustment of the plate 40 and rod 34, indicating one extreme of adjustment on solid lines and the opposite extremeon dotted lines, the normal position, not shown, being an intermediate one. when the rod 34 is rotated, the position of that portion of the gripper bar 4 which rests upon the rollers 3| and 33 is altered. Upon rotation of the shaft 34 clockwise, the rollers 34 are moved away from the rollers 3i, toward the position shown in solid lines and allowing the 'bar 4 to move to the right, with the axis of the portions of the bar engaging the roller 33 shifting on an aren ate line about the center of the roller 3|. When the rod 34 is rotated counter-clockwise, the axis of the eccentric 34' moves to the left. with resultant change in position of the rollers 33 toward the rollers 3I and shiftingof position of that portion of the gripper bar to the left. or toward the position shown in dotted lines in Figure 8.

By locating the pairs of rollers toward the center of the channel 20 and of the gripper bar 4. the ends ofthe latter being held'in' fixed position within the channel by the cam I pressing on the carrier-member I0, adjustment of the shaft 34 will cause'a bowing of the gripper bar 4 toward its center, which rests upon the rollers, and consequent shifting in position of the gripper fingers carried by the gripper bar. This shifting of position of the gripper fingers, which grip the forward or leading. edge of the sheet, will warp the sheet for correcting register, as previously described.

The plate 40 is shown as placed against a graduated scale 44 and having a pointer or indicator formed thereon to cooperate with the scale.

. ter eccentric to the center or axis of the first I and the bolt 42 serves to lock the plate in adjusted position. Thus the operator can adjust the eccentric shaft 34 to provide the desired bowing of the gripper bar, either in the direction of movement of the cylinder or contrary thereto, and in the degree desired to produce the required warping of the sheet gripped by the gripper fingers for correcting register at the trailing end of the sheet, or for avoiding the wrinkling of sheets that may be ruilled. The adjustment for each unit may be different to properly correct the register as to that printing unit. In practical operation it is usually the third orlater units of the multiple j unit press which require adjustment, to correct faulty register, but correction to prevent wrinkling may require the adjustment on other units.

Bands 00 may be formed upon the periphery of the gripper bar 4 at the point where it rests upon the rollers 3| and 33 to prevent wear.

The present invention may also be adapted for use in continuous operating sheet fed multiple unit presses employing transfer cylinders. Such a press is shown diagrammatically in Figure 9 of the drawings, wherein the sheets are delivered by the feeder cylinder IN to an impression cylinder I02, thence to transfer cylinders I03 which deliver'the sheet to a second impression cylinder I04; and thence to a final delivery cylinder I05.

It is to be understood that the impression cylinde'rs I02 and" I04 cooperate with blanket or printing cylinders I06, between which respective couples the; sheet travels.

, In its course from cylinder to cylinder of the press, the sheet is gripped by sets"of gripper fingers incorporated in each cylinder which hold the leading edge of the sheet, releasing it when it is transferred to the succeeding cylinder, and is received by the sets of gripper fingers incorporated therein. While only two units have been shown, the invention may be applied to a press having any desired number of units.

In Figure 10 is illustrated a top plan view of an impression cylinder I04 incorporating a gripper bar IIO to which is attached a plurality of sheet gripping units III. The gripper bar IIO together with its associated gripping mechanism is located in a channel I I2 formed in the body of the cylinder I04 longitudinally thereof and at its surface. The bar I I0 is rigidly anchored in place in any suitable manner, as by means of the bolts II3 which extend through the end plates of the cylinder I04 into the bar.

The sheet gripping units III comprise blocks II4 securely attached to the bar H0 at intervals along its length and having gripping elements III. A shaft II6. extending parallel to the bar H0 is journaled in the blocks II4 of the gripping units II I. To this shaft I I6 are rigidly attached gripping fingers III for cooperation with the elements II5 of the blocks II4. Rotation of the shaft IIG opens and closes the grippers, by establishing or releasing the contact between the fingers II! and the block element II5, as desired. The shaft IIS may be journaled at one end in the end plate of the cylinder I04 and its opposite end extends'through the end plate at the other end of the cylinder I04. To this end of the shaft H6 is attached a rocker arm --I20, one s 7 the shaft 1 I sufilciently to open and close the ripping jaws of the units .I I I. The mechanism forms no part of the present invention and any satisfactory mechanism for operating the gripper units may be substituted.

on the opposite side of the gripper bar I I0 and at its" center is'attached a'block I30 having a bore in which is inserted a crank rod extension I3I. The extension I3I is formed at one end of a crank I33 attached to a rod I33 which extends parailel'to the bar 0 to one end of the cylinder I03, The rod I33 is iournaled in an extension'lfl asraoaa Whenjthe arm I35 is pivoted on a point to the left of the pivot center of the arm I40, the cam will act to raise the arm I35, rotating the crank shaft I33 counterclockwise, and through its crank member I 32 will bend the gripper bar IIO backward at itscenter. This will cause the paper gripped by theunits III to be bowed at its center to warp the trailing corners of the for'medin the sidewall of the channel III and extends through the end plate of the cylinder I04.

On the end ofthe rod I33 extending beyond the' end of the cylinder I04 is attached a rocker arm'I35 (Fig. 11) which is keyed to the rod I33 for -movement therewith. At the end of the rocker arm' I35 is rotatably attached an arm I30 end of the cylinder I04 by means of a pivot I4I which rotates within a corresponding bore I42 inder I04. The pressure of the spring I41 exerted again t the. block I46 and a collar 143 secured to the rod I45 constantly urges the arm I turn counter-clockwise as seen in Fig. 11.

The opposite end of the arm I40 carries a cam roller I50 which cooperates with a cam track or surface I5I, the latter being rigidly attached to the frame of the press or otherwise suitably fixed .in place. As the roller I50 rides over the cam surface I5I, the arm I40 will be rocked when the cam surface rises (as at I52). The configuration of the cam surface may be designed with any number of rises, according to the number of times per rotation of the cylinder I04 it is desired to bend the gripper bar H0. The spring biased rod I serves to keep the cam roller in continuous contact with the cam surface.

trailing edge of the sheet has shrunk due to conditions previously pointed out.

The-degree of bowing-of the bar III and the extent that the paper is warped in either direc- ,.tion -'is-controlled by the setting of the pivot point of the arm I33 within the arcuate slot 3. The scale is provided for the operator's use in setting the mechanism to provide the desired extent of bowing In Fi ures 9and 11 a centerline I is shown through'the axis of the cooperating cylinders I04 and Iltfithe impressionand blanket cylinders respectively, bis'ecting the'point of impression. "In

operation it is desirable that the sheet be warned by the gripper bar mechanism, reaches the point of impression. The cam'will act to release the action of the bowing mechanism shortly after the leading edge of the sheet has passed the impression point; Regardless of the cylinder to which When the axis of the bolt I31 and sleeve member I35 is in line with the axis of the pivot meniber I, the rocking of the arm I40 will have no effect on the associated parts. However, when the bolt I31 is loosened and moved to the right or left of the axis of the pivot I4I, movement of the rocker arm I40 will serve to raise or lower the end of the arm I35 and rotate the shaft The arm I35 has an indicator on its lower end which cooperates with a scale Placed on the right of the pivot center of the arm I40, as seen the structure is applied, the warping action should begin before the sheet reaches the point of impression.

In the chain conveyor type of press described in connection with Figure 3, the gripper bar is carried through the successive units-and holds the sheet throughout its passage through the unit. Accordingly. the ilexure of this bar by comparison with its flexure, if any, at the time when.

it receives the sheet from the sheet registering and feeding unit determines the distortion to which the sheet is subjected at any given unit.

In the transfer cylinder type of'press, described in connection with Figure 9, the sheet is passed along from cylinder to cylinder,'the grippers of each cylinder surrendering the sheet to the grippers of the succeeding cylinder. In this type f construction, therefore, the leading edge of the sheet may be distorted at any desired point and passed along to succeeding grippers which are thus called upon merely to maintainthe distor." tion. While it is preferred to displacethe gripper.

elements of the impression cylinder after they have receivedthe sheet, it will be clear that this is not necessary. For example, the grippers of a transfer cylinder may be displaced during the;

time when the sheet is being surrendered to a succeeding cylinder and the sheet will then be carried through to the impression point in its distorted condition. Alternatively, if the rippers are displaced when receiving the sheet, merely.

permitting them to return to their normal position will impart the desired distortion. While it is preferred. to displace the gripping elements of the impresison cylinder in the manner shown, similar effects can be obtained by displacing the cylinder;

gripper elements of the; transfer. orregistering I rollers and shafts upportin pose, and is shown as applied to the conveyor type of press. The cylinder l2, and the chain conveyor, as well as the gripper bars and the the same, being the same as in Figures 4 and require no further description' /Instead of adjusting the shaft 34 by means of a member fixed to the cylinder and rotatable therewith, an arrangement is provided for adjusting the angle of this shaft as the leading edge ofthe sheet approaches and until it passes the irhpnession line of the printing cylinder. This adjustment is effected by means of a cam 200 aflixed to the frame structure 20l as by means of supports 202 and having an adjustable section 203 pivoted at one. of the supports 202, as indicated, and movable through a rangeof adjustment by means of the rod 204. The rod 204 is pivotally connected to the adjustable cam section 203 at 205 and is adjusted by means of a hand wheel 206 secured to a screw-threaded bushing having a collar 201. A poppet 208 mounted on-the frame 20! as by means of a support 209 prevents movement of the rod 204, except by rotating the handwheel. By this means, the rise or fall of the cam 200203, through the appropriate arc of the cylinder, may be adjusted as desired. A roller M is carrled'by an arm 2 keyed to the shaft 34, and is pressed against the cam by the spring H2. The angular position of shaft 34 and hence the position of the gripper bar supporting rollers is thus determined by the adjustment of the cam. With thecam section 203' adjusted as shown, the gripper bar will be bowed before and for a short time after the leading edge of the sheet reaches the impression point so as to advance the center of the sheet and thus contract the trailing edge as before described.

What I claim is:

1-. In multiple unit offset printing, the method of correcting for expansion of the trailing end of a sheet following a first impression, which comprises leading the sheet through a later printing couple with the middle of the leading edge of the sheet advanced with reference to the corners, whereby the trailing end of the sheet is contracted to bring the first impression into registerwith that of the later printing couple.

2. In multiple unit rotary printing on a machine of the type in which sheets to be printed are carried through the printing couples by grip per bars having gripping elements settable for gripping and holding the leading edge of a sheet at points spaced across its width, the method of adjusting the trailing end of a sheet for register which comprises bowing a gripper bar carrying the sheet, in a direction to curve the leading edge of thesheet in a plane tangent to its path of travel, before it reaches an impression point and during partof the passage of a sheet therethrough, whereby a later impression is brought into register with a previous impression.

3. In multiple unit rotary printing on a machine of the type in which sheets to be printed are carried through the printing couples by gripper bars having gripping elements settable for gripping and holding the leading edge of a sheet at points spaced across its width, the method of adjusting the trailing end of a sheet for register which comprises bowing a gripper bar carrya l0 ing a sheet, in a edge of the sheet in a plane tangent to its path of travel, at the impression point and during part of the passage of a sheet therethrough, whereby a later impression is brought into register with a previous impression.

4. In a sheet-fed rotary printing machine, the

method of correcting transverse register which comprises shifting the circumferential -position of the middle of the leading edge of a sheet with reference to the unit printing cylinder after it leaves one unitof the press and before it is delivered to the succeeding unit thereof, when the trailing end of said sheet has spread or shrunk laterally following a previous impression.

5. In a sheet fed rotary printing machine including a plurality of printing couples and aligned members gripping the sheets at intervals across their leading edges for holding them against the surface of a cylinder of a printing couple, the combination with said gripping members of adjustable means for displacing certain of said gripping members out of alignment with others of said gripping members, whereby the leading edge of the sheet gripped thereby will be warped during its passage through the said printing couple.

6. In a sheet-fed rotary printing machine including a plurality of printing couples and aligned members gripping the sheets at intervals across their leading edges for holding them against the surface of a cylinder of a printing couple, the combination with said gripping members of adjustable means for displacing said gripping members at the middle of the leading edge of'a sheet relative to those adjacent its sides,

whereby the leading edge of the sheet gripped their leading edges for holding them against the surface of a cylinder of a printing couple, the combination with said gripping members of adcluding a plurality of printing couples and aligned members gripping the sheets at intervals across their leading edges for holding them against the surface of a cylinder of a printing couple, the combination with said gripping members of adjustable means for displacing said gripping members at the middle of the leading edge of a sheet relative to those adjacent its sides, and cam means affixed to the machine frame for operating said adjustable means, whereby the leading edge of the sheet gripped thereby will 'be warped during its passage through the said printing 4 couple.

9. In a sheet-fed rotary printing machine including a plurality of printing couples and aligned members gripping the sheets at intervals across their leading edges for holding them bers at the middle of the leading edge of a direction to curve the leadingfor operating the last said means, whereby they leading edge of the sheet gripped thereby will be warped during its passage through the said printing couple.

'10. Inasheet-fed rotary printing machine ineluding a plurality of printing couples, and in combination, members for gripping the sheets to be printed at intervals across their leading edges for holding them against the surface of a cylinder of a printing couple, a bar carrying said gripping, members, the said gripping members being arranged for holding the portions of the sheet gripped thereby at fixed distances from the bar and adjustable means for bowing the said bar. I

11. In a sheet-fed rotary printing machine including a plurality of printing couples, and in combination, membersfor gripping the sheets at intervals across their leading edges for holding them against the surface of a cylinder of a printing couple, a bar carrying saidgripping members,

means embodied in the printing couple for supporting said bar, and adjustable means carried by said supporting means at the end of the cylinder for bowing said bar whereby the alignment of the gripping members attached thereto may be altered for warping the sheet gripped thereby during its passage through said couple;

12. In a sheet fed rotary printing machine including a plurality of printing couples, and in combination, members for gripping the sheets at intervals across their leading edges for holding them against the surface of a cylinder of a printing couple, a bar carrying said gripping members, means embodied in the printing couple for supporting said bar, adjustable means carried by said supporting means for bowing said bar, and cam means affixed to the machine frame for operating said adjustable means, whereby the alignment of the gripping members attached thereto will be altered for warping the sheet gripped thereby during its passage through said couple.

13. In a sheet-fed rotary printing machine including a plurality of printing couples, and in combination, members for gripping the sheets at intervals across their leading edges for holding them against the surface of a cylinder of a printing couple. a bar carrying said gripping members, means embodied in the printing couple for supporting said bar, means carried by said supporting means for bowing said bar, and adjustable means amxed to the machine frame for'operating the last said nuans, whereby the alignment of the gripping members attached thereto will be altered for warping the sheet gripped thereby during its passage through said couple.

14. In a sheet-fed printing machine including i a plurality of printing couples, and in combination, conveyor means for feeding the sheets through the printing couples, a gripper bar carried by said conveyor means, gripping members carried by said bar for gripping the sheets across their leading edges, and ad ustable means for bowing said bar, whereby the alignment of the said grinning members will be altered to warp the leading ed e of a sheet during its passage through a printing couple.

15. In a sheet-fed printing machine including a plurality of printing couples. and in combination, conveyor means for feeding the sheets through the printing couples, a grip er bar carried by said conveyor means, gri ping members carried by said bar for gripping the sheets across their leading edges, adjustable means for bowing said bar, and cam means aillxed to the machine frame for operating said adjustable means, whereby the alignment of the said gripping members will be altered to warp the leading edge of a sheet during its passage through a.. printing couple.

16. In a sheet-fed printing machine including a plurality of printing couples, and in combination, conveyor means for feeding the sheets through the printing couples, a gripper bar carriedby said conveyor means, gripping members carried by said bar for gripping the sheets across their leading edges, means for bowing said bar, and adjustable means affixed to the machine frame for operating the last said means, whereby the alignment of the said gripping members will be altered to warp the leading edge of a sheet during its passage through a printing couple.

17. "In a sheet-fed printing machine, and in combination, a cylinder, gripping members carried thereby for gripping sheets across their leading edges, and a plurality of relatively adjustable means spaced across the cylinder for displacing said gripping elements at the middle of the leading edge of a sheet relative to those adjacent its sides, wherebythe center portion of the leading edge of the sheet may be advanced or retarded.

18. In a sheet-fed printing machine, and in combination, an impression cylinder, gripping members carried thereby for gripping sheets across their leading edges, and a plurality of relatively adjustable means spaced across the cylinder for displacing said gripping elements at the middle of the leading edge of a sheet rela-'- tive to those adjacent its sides, whereby the center portion of the leading edge of the sheet may be advanced or retarded.

19. In a sheetfed printing machine, and in combination, an impression cylinder, gripping members carried thereby for gripping sheets across their leading edges, adjustable means for displacing said gripping elements at the middle of the leading edge of a sheet relative to those adjacent its sides, and comprising co-operating members'upon said cylinder and upon the ma chine frame, whereby the center portion of the leading edge of the sheet may be advanced or retarded while the said gripping elements are passing through a predetermined arc of movement including the impression point.

20. In a sheet-fed printing machine, and in combination, a cylinder having a channel for a gripper bar, means .within said channel for bowing said bar, the said means comprising a plurality of relatively adjustable elements for engaging the bar towardits ends and toward its middle, and means atthe end of said cylinder for adjustably positioning the said adjustable elements.

21. In a sheet-fed printing machine, and in combination, a cylinder having a channel for a gripper bar, means within said channel for bowing said bar, means associated with said cylinder for operating said bar to grip and release sheets, and means at the end of said cylinder and operating in timed relation to the last said means for adjustably operating the said bowing means.

22. In a sheet-fed printing machine, and in combination, a printing cylinder, a cooperating impression cylinder having a channel for a gripper bar, means within said channel for bowing said bar, the said means comprising a plurality of relatively adjustable elements for en- 13 gaging the bar toward its ends and toward its middle, and means at the end of said cylinder and operating through a predetermined are before and after the impression point for adjustably positioning the said adjustable elements.

23. In a sheet-fed printing machine, and in combination, a cylinder having a channel for a gripper bar, means within said channel for bowing said bar and comprising a shaft carrying a plurality of eccentric bowing elements and arranged relative to said bar for deflecting the middle thereof in the same direction relative to both of its ends upon angular movement of the shaft, and means at the end of said cylinder for adjusting the angular position of the said shaft to operate the said bowing means.

24. In a sheet-fed printing machine, and in combination, cooperating cylinders, a set of gripping members carried on one of said cylinders, a set of gripping members carried on the other of said cylinders, means for driving said cylinders in timed relation, means for transferring sheets 4 from the gripping members of one of said cylspaced across one of the said cylinders and operable to position the gripping members of one of said sets so as to deflect the middle members thereof relative to both end members.

25. In a sheet-fed printing machine, and in combination, a cylinder, a gripper bar carried thereby. gripping members attached to said bar and spaced therealong for gripping a sheet across its leading edge, and means for bowing said bar during its passage through a predetermined arc of movement of said cylinder, the last said means comprising means for engaging the middle of the bar and deflecting the same in the same direction relative to both of its ends.

26. In a sheet-fed printing machine, and in combination, 9, cylinder, a gripper bar carried thereby, gripping members attached to said bar and spaced therealong for gripping a sheet across its leading edge, means for bowing said bar during its passage through a predetermined arc of movement of said cylinder, the last said means comprising means for engaging the middle of the bar and deflecting the same in the same direction relative to both of its ends, and adjustable means at the end of the said cylinder for operating the said bowing means.

27. In a sheet-fed printing machine, and in combination, a cylinder, a gripper bar carried thereby, gripping members attached to said bar and spaced therealong for gripping a sheet across its leading edge, means for bowing said bar during its passage through a predetermined .arc of movement of said cylinder, the last said means comprising means for engaging the middle of the bar and deflecting the same in the same direction relative to both of its ends, and cooperating adjustable means at the end of said cylinder and upon the machine frame for operating the said bowing means.

28. In a sheet-fed rotary printing machine including impression and printing cylinders, members gripping the sheets at intervals across their leading edges, a gripper bar carrying and actuating said gripping members, and a, conveyor mechanism for said gripper bar, the said impression cylinders having channels for receiving said gripper bar, the combination with an impression cylinder of means located in a said channel for supporting and bowing said gripper bar, and adjustable means at the end of the impression cylinder for operating the last said means.

29. In a sheet-fed rotary printing machine including impression and printing cylinders, members gripping the sheetsat intervals across their leading edges, a gripper bar carrying and actuating said grip-ping members, and a conveyor mechanism for said gripper bar, the said impression cylinders having channels for receiving said gripper bar, the combination with an impression cylinder of means located in a said channel for supporting and bowing said gripper bar, the said means including rollers within said channel for supporting the said gripper bar, an eccentric shaft carrying said rollers, and adjustable means at the endof the impression cylinder for varying the angular position of said shaft.

ALEXANDER J. ALBRECHT.

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

UNITED STATES PATENTS