US3164087A

US3164087A - Printing machines

Info

Publication number: US3164087A
Application number: US35046A
Authority: US
Inventors: Arthur E J Owen
Original assignee: Multigraphics Inc
Current assignee: AB Dick Co
Priority date: 1960-06-09
Filing date: 1960-06-09
Publication date: 1965-01-05
Anticipated expiration: 1982-01-05

Description

Jan. 5, 1965 A. E. J. OWEN 3,164,087

PRINTING MACHINES Filed June 9, 1960 WT MW'WF 'W H I 3B Z9 Inventor flTHzur Eu Gwen &

United States Patent Ofiiice 3,lh4,8? Patented Jan. 5, 1965 sas es! PRENTHNG MACHINEfi Arthur E. 11. Owen, Gates Mills, 01bit), assiguor to Addressograph-Multigraph Corporation, Cleveland, Ohio, 3 cerporation of Ghio Filed Shine 9, 1960, Ser. No. 35,046 5 (Ilaims. (Cl. 1131-142) This invention relates to printing machines and especially to machines wherein an image is transferred from a master to a blanket and thereafter to a sheet fed between the blanket and a cooperating platen or impression cylinder, the machine therefore being of the kind that operates on the offset principle.

In printing machines of the kind operating on the offset principle, a replaceable blanket is mounted on the blanket cylinder so that the surface of the blanket receives an inked image from a master and such image is then printed on a sheet passed between'the blanket and the platen cylinder. Such blankets heretofore have been composed of rubber or have been of such nature that a rubber surface was afforded to receive the image from the master. Machines of this kind are so arranged that a master bearing a particular image may be readily substituted for one bearing another image. Inasmuch as what may well be called a residual image from one master usually remains on the surface of the blanket when a new master is substituted for one previously mounted in the machine, and since in most instances it would be objectionable to have an imprint efiected from such a residual image, it is common to thoroughly clean the surface of the blanket as an incident to a change of masters in the machine. Heretofore, this has been effected either manually by-resort to a swab or special equipment such as that disclosed in United States Reissue Patent Re. 24,739. Moreover, heretofore when cleaning of the blanket has been effected as aforesaid, a suitable cleaning solution has been resorted to tofacilitate removal of any residual or previous image on the surface of the blanket. Such blanket cleaning operations are time consuming and this has been particularly objectionable in those instances where relatively few transfers fromthe master to the blanket and thence to the sheets receiving the impressions are being effected-as in the instance where, for example, a dozen or less impression operations are effected. 4

It is therefore the primary object of the present invention to supplant a conventional blanket afiording a image may be expeditiously removed as, for example, by removing an image remaining on the surface of the blanket in but a single movement of the blanket past a blanket cleaning means.

Another object of the invention is to resort to a blanket surface capable of retaining an image picked up from a master for the purpose of transferring the same to a sheet to receive the same but from which surface any image remaining thereon is readily removable due to inherent characteristics of the material affording the surface. Still another object of this inventionis to provide a mechanism which may be expeditiously engaged with a blanket surface .of the aforesaid character to remove'any residual image therefrom and an ancillary object is to include in the mechanism -an arrangement whereby a fresh or clean surface may be presented to'the blanket surface as required to insure effective-removal of any residual image from the blanket surface.

I A more specific object of this invention is to resort to a blanket having its image receiving face composed of Teflon resin material, that is, a polytetrafluoroethylene material. I

Other and further objects of the present invention will be apparent from the following description and claims and are illustrated in the accompanying drawing which, by way of illustration, shows a preferred embodiment of the present invention and the principles thereof and what is now considered to be the best mode contemplated for applying these principles. Other embodiments of the invention embodying the same or equivalent principles may be used and structural changes may be made as desired by those skilled in the art Without departing from the present invention and the purview of the appended claims.

' In the drawings:

FIG. 1 is avertical sectional view of a typical machine operating on the offset principle and wherein a blanket .of the present invention is incorporated;

general nature of the machine shown in the accompany-.

ing drawing. Thus, the machine as illustrated in the accompanying drawing includes a cylinder11 on the periphery of which a planographic master or plate bearing an image to-be reproduced may be mounted. The machine also includes a cylinder 12 on the periphery of which a blanket B embodying the present invention may be mounted. The plate P of the-blanket B may be re movably secured to the peripheries of the cylinders on which they are mounted in any suitable manner as, for

example, that disclosed in aforesaid Patent No. 2,165,231. The respective thickness of the plate and blanket are so related one to the other, and to the diameters of the cylinders on which plate and blanket are respectively mounted, that'the surfaces of the plate and blanket are in contact one with the other when the cylinders are set in rotation in the direction of the arrows shown on the respective cylinders in FIG. 1. The blanket B on the periphery of the cylinder 12 is adapted to cooperate with a platen or impression cylinder 13, the arrangement being such that sheets disposed on the table 14 may be advanced one at a time into the bight between the 1 cylinder 13 and the blanket B to therebyhave an impression carried by the surface of the'blanket B transferred to such a sheet. After the sheet has 'passed between the bight between the blanket B and the platen 13, the sheets are collected in a suitable hopper such as 15.

These cylinders 11 and 12 are respectively mounted on parallel shat-ts 16 and 1'7, the opposite ends of which are journalled in suitable bearings afforded in the frame F of the machine as disclosed, for example, in aforesaid Patent No. 2,165,321. 'A gear as 18 is associated with each cylinder 11 and 12 and such gears are meshed one with the other. Moreover, a gear "as 19 meshes with the gear 18 associated with cylinder 11 and also with a gear as 29 that in turn meshes with a gear 21, each of such gears being mounted on shafts journalled in bearings afforded in the frame of the machine. The

gear Z1 i-s mounted on a shaft 22 on which there is" mounted a pulley 23 about which a belt 24 is passed,

the surface of the blanket. 1 bearing a'particular image isremoved from the surface of the cylinder ill and another plate bearing a different image is substituted therefor, it-has heretofore said belt also passing about a pulley 25 on the shaft of the motor M that i 'suitably mounted in the frame F of the machine. Thus, when the motor M is in operation the cylinders 11 and I 12 are driven in synchronism with the surface of the blanket B running in contact with the surface of the printing plate P. 7

As is customary in the art, an ink receptive or nicephil-ic image is afforded on the surface of the plate P and ink is applied thereto through the ink train gen erally indicated by 26 which may be in the nature of that shown in aforesaid Patent No. 2,165,231. The surface of the plate P, other" than that whereat an image appears is hydrophilic, and a conventional repellant or moistening solution is applied to this portion of the plate through the moistening unit generally indicated by 27 which may also be in the nature of that disclosed in the just referred to patent. Thus, when the cylinders 11 and 12 are set in rotation, ink is supplied to the oleophilic image on the surface of the .pla e l and a dampening solution is also applied to thesurface of the plate and,-as the cylinders 12 and i2continue in rotation, the

ink frornthe image on the surface of the plate P transferred to the surface of the blanket B on the cylinder 12. Thereafter, as sheets are passed through the bight between the. blanket l2 and the'cylind'er 15 the I ink image on the surface of the blanket B is transferred to such sheets. As is well understood in the art, the

image onthe surface of the plate P is direct reading so that the image ist-ransferred to thesurface of the blanket 'B in reverse image and therefore in turn the image is is transferred to the surface of the blanketB is not completely transferred'to sheets passing between the blanket B and the platen or impression cylinder 13 so thatwhat is usuallyreferred to as aresidual image remains on Hence, when a plate as been the practiceto resort to special solutions to insure that any residual image remaining onthe blanket B will be removed therefrom prior to. the time ink from the image on a newly installed plate? is transferred to the blanket B. Sometimes this removal of the residual v image has been effected manually by'resorting'to a swab that has been immersed in a cleaning solution and in other instances this has been effected by resorting to special equipment such as that shown in, for example, US. Reissue Patent Re. 24,739. Whenspecial equipment, such as' -that just referred to, has been utilized to efiect removal of a residual image from the rubber surface of the blanket it has been necessary to effect several revolutions of the cylinder 12 to insure that all the residual image was removed.

image was removed manually by resort to a swab, as I When the residual aforesaid, the blanket cylinder 12; has usually been ad.- vanced manually in a step-bysstep manner so as to present succeeding portions thereof in position to have'the surface of the blanket thoroughly cleaned. In any event, however, heretofore the removal of a residual image i B and the impression cylinder l3. Even though any image transferred to a blanket having a polytetraiiuoroethylene surface is usually completely transferred to a sheet passed between the bight between such a blanket and the impression cylinder 13 there may be instances where a so-called residual image may remain on the surface of the blanket. For reasons stated hereinabove, it is usually necessary to remove any such residual image from the surface of the blanket prior to the time anothe image is to be transferred thereto from a plate as However, 1 have found that any residual image on the blanket of the present invention may be readily removed therefrom usually by passing the surface of the blanket past means effective to remove any such residual image but a single time.

While the removal of any residual image remaining on the surface of a blanket as B embodying the present invention may be readily effected by passing a dry swab of suitable material over the surface of the blanket usually but a single time, I have found it advantageous to provide suitable means whereby fabric blanket cleaning material may be readily engaged with the surface of the blanket B so that the blanket may be caused to pass thereby to have any residual image on the blanket removed therefrom.

A manually operable form of means suitable for this purpose is ilustrated in the accompanying drawing and referring thereto a frame as 28, that is substantially U- shaped in elevation, is provided and the free ends of the arms of such frame are pivotally mounted in the frame F of the machine as indicated at 29 and 3b. In profile the frame 28 includes inwardly extending arms as 31 which merge into upwardly extending arms as 32 which in turn merge into outwardly extending arms as 33.

An upwardly extending lug as 3d is provided on each of the arms 31 and a shaft as 35 has opposite ends thereof removably journalled in such lugs. A downwardly extending lug as 36 is provided on each of the arms 33 and a shaft as 37 has opposite ends thereof removably journalled in such lugs. One end of a fabric web as 38 is attached to the shaft 37 and such web is wound on the shaft so that from the rubber surfaceof a blanket as B has been-time consuming, which is ofttimes objectionable. In accordance will the present invention, at least'the image receiving surface of the blanket as B is' composed of polytetrafluoroethylene and-is readily receptive to conventional inks applied to an image on a plates-s. E;

An image. so received on the surface 'of'a ,blanket'of this invention is readily picked up therefrom when a sheet is passed through the bight between the blanket the web may be withdrawn therefrom. A plate 39 extends between, and is attached-to, the arms 32 of the frame 28 and is so disposed that the medial portion of the vertical extent thereof is disposed slightly above the horizontal axial plane of the shaft 17 of the cylinder l2. when the frame 23. is in inoperative position as shown in full lines in FIG. 1. A pad 4! of resilient material, such as sponge rubber or the like, is mounted on the inwardly disposed face of the platew. As the web 38 is withdrawn from the supply thereof wound on the shaft 37 the web is passed over the exposed face of the pad to and thence to the shaft 35 to which the free end of the web is connected in any suitable way. A knob or handle as 41 is associated with one end of the shaft 35 and by rotating the same the web 33 may be caused to wind up on the shaft 35. In this way a clean portion of the web 38 may be disposed over the surface of the pad 49 whenever the need so to do so arises. Spring washers as SW are respectively disposed between the inner faces of the lugs as 34 and adjacent shoulders on the shaft 35. Similar spring washers SW are respectively disposed between the inner faces of the lugs 36 andadjacent shoulders on the shaft 37. The'spring washers SW impress a friction drag on the

shafts

35 and 37 whereby the web 3?; may be maintained in a taut condition. It willbe understood that any suitable means may be resorted to to provide such a friction drag in order that the web will be maintained taut.

A handle as 42 is provided on the body of the U-shaped frame 28 and-may be grasped so as to thereby rock the frame 2% about the pivotal supports 29 and 3h into the broken line position thereofshown in FIG. '1. 7 So to do brings the portion of the web 33=overlyingthe pad 4i: into engagement with the adjacent surface of the blanket B as shown in broken lines in FlG.'1, When such a portion of the web 38 is engaged with the blanket B the cylinder 12 is rotated to cause the surface of the blanket to move past the portion of the web 38 disposed over the pad 40 and in so doing anyresidual image, on the surface of the blanket B is picked up by the web 38 usually in but a single movement of the surface of theblanket past the web.

As best shown in FIG. 4, a spring 43 is disposed about the boss of the pivotal mounting 30 of one of the arms 31. The end 44 of such spring is fixed to the boss and the opposite end 45 of the spring is engaged with the arm 31 so that the spring will be effective to bias the frame 28 in a counterclockwise direction as viewed in FIG. 1. A similar spring bias is also associated with the other arm 31 of the frame 28. Rods as 46 are mounted in the frame F and are disposed in position to be engaged by the outwardly disposed faces of the lugs as 36 to thereby limit the biasing effect of the spring 43 so as to thereby normally dispose the frame 28 in the full line position thereof shown in FIG. 1 with the portion of the web 38 disposed over the pad 40 out of engagement with surface of the blanket B.

As has been stated, at least the surface of the blanket B is composed of a polytetrafluoroethylene material. Such a surface may be afforded either by resort to polytetrafiuoroethylene film of appropriate thickness, but more advantageously such material is applied as a coating or is impregnated into suitable porous structures of which canvas duck or other fabric are illustrative. It is essential, however, that the surface of the polytetrafluoroethylene that is to receive the image be smooth, and to this end the surface may be calendared to insure thedesired smoothness. If resort is had to an aqueous dispersion of polytetrafluoroethylene, such dispersion is heated to a suflicient degree to remove the water. In order that a strongcontinuous film will be afforded, such polytetrafluoroethylene material may be sintered at 680700 F. after drying. In some instances it may be advantageous to resort to a relatively thin film of polytetrafluoroethylene material and to mechanically connect the film to a suitable support of appropriate thickness as by riveting or the like. The essential aspect of this invention is that a strong, smooth film of polyeterafiuoroethylene material afford the surface of V the blanket that is to receive the image, since so to do insures proper transfer of ink from the image, and therefore, the image to the sheet that is to receive the same, and this also insures that any residual image or the like remaining on the surface may be expeditiously removed therefrom, as explained hereinabove.

The blanket B, as shown in FIG. 2, is rectangular in outline. At least one of the shorter ends (and desirably both shorter ends) of the blanket is scalloped and has slots formed in the segments between recesses afforded in the scalloped edge. This enables the ends of the blanket" to be readily attached in the means afforded in offset printing machines to secure the blanket on the periphery of the blanket cylinder of such a machine. However, other suitable attaching elements may be afforded at one or both of the shorter ends of the blanket without departing from the puview of this invention.

.In operation a plate as P will be mounted on the cylinder 11 in the usual'manner. Thereafter, ink is applied to the image on the plate through an ink train as 26 and'a moistening or repellent solution is applied to the plate through a moistening attachement as 27. The ink is of such nature that it will be picked up by the oleophilic image on the surface of the plate P. Then, as succeeding portions of the surface of the plate P come into contact with succeeding portions of the blanket B, ink from the image will be transferred to the surface of the blanket B.

Thereafter, as successive portions of the blanket B move into contact with a sheet disposed between the platen or impression cylinder 13, ink on the surface of the blanket will be transferred to the sheet to thereby afford an impression on the sheet of the inked image on the plate P. When the desired number of sheets to be so imprinted have been advanved from a table as 14 through the bight 6 V between the blanket and the impression cylinder operation of the machine is interrupted. The plate as P which has been mounted on the cylinder 11 is then removed so that a new plate may be substituted therefor. Prior to the time a new plate as'P is mounted on the cylinder 11, the cylinder 12 will be setin rotation and by grasping the handle 42 the portion of the web 38 disposed over the pad 4% will be brought into engagement with the surface of the blanket B. As succeeding portions of the blanket B come into contact with the aforesaid portion of the web overlying the plate 40 any residual image or the like thereon is picked up by the web 38. Usually no more than a single revolution of the cylinder as 12 will be required to remove any residual image from the surface of the blanket B when such surface is a polytetrafluoroethylene material in accordance with this invention.

As the portion of the web 38 disposed over the pad 40 becomes soiled by reason of picking up residual images and the like from the surface of the blanket B, the web may be advanced by operating the handle 41 to thereby withdraw the Web from the shaft 37 and to wind the same on the shaft 35 and such an operation will be effected whenever in the judgment of the operator of the machine it is necessary so to do.

While I have illustrated and described the present invention from the standpoint of one embodiment, it will be appreciated that this is capable of variation and modification, 1

and I therefore do not wish to be limited to the precise details set forth, but desire to avail myself of such changes and alterations as fall within the purview of the following claims. 1

I claim:

1. In an offset printing machine wherein an image carried by a master mounted on a plate cylinder is transferred to a blanket on a blanket cylinder and from thence to a sheet fed between the blanket and a cooperating impression cylinder, a blanket secured to said blanket cylinder having the image-receiving surface thereof composed of polytetrafiuoroethylene.

2. A blanket adapted to be removably mounted on the blanket cylinder of an offset printing machine, said blanket being of generally rectangular outline and having attaching elements integrally associated with at least one end thereof, said blanket having at least one surface composed of polytetrafluoroethylene.

3. In an offset printing machine wherein an image carried by a master mounted on a plate cylinder is transferred to a blanket on a blanket cylinder and from thence to a sheet fed between the blanket and a cooperating impression cylinder, a blanket secured to said blanket cylinder having the image-receiving surface thereof composed of polytetrafluoroethylene, and means engageable with the image-receiving surface of the blanket when the blanket is mounted on the blanket cylinder for removing any residual image or the like from such surface in a revolu tion of the blanket cylinder during which the means is engaged with said surface.

4.v In an offset printing machine wherein an image carried by a master mounted on a plate cylinder is transferred to a blanket on a blanketcylinder and from thence der for removing any residual image or the like from said blanket surface in a revolution of the blanket cylinder.

during which the fabric surface blanket surface.

5. In an offset printing machine wherein an image carried by a master mounted on a plate cylinder is transis engaged with said ferred to a blanket on a blanket cylinder'and from thence to a sheet fed between the blanket and a cooperating-impression cylinder, a blanket secured to said blanket cylini der having the image-receiving surface thereof composed of polytetrafiuoroethylene, means includinga web of fabric afiording a fabric surface engageahle with the image-receiving surface of the blanket When the blanket is mounted on the blanket cylinder'for removing any residual image or the like from said blanket surface in a revolution of the blanket cylinder during which the fabric surface is engaged with said blanket surface, and means for advancing said Web so that succeeding portions of the Web will afford the aforesaid fabric surface. W

Referenees Cited in the file of this patent UNITED STATES PATENTS Janke et al Nov. 24, 1959 Carothers -1 Aug. 12, 1941 Frost -2 July 31, 1951 Battey Feb. 12, 1952 Osdal Aug. 29, 1961 FOREIGN PATENTS Great Britain July 2, 1952

Claims

1. IN AN OFFSET PRINTING MACHINE WHEREIN AN IMAGE CARRIED BY A MASTER MOUNTED ON A PLATE CYLINDER IN TRANSFERRED TO A BLANKET ON A BLANKET CYLINDER AND FROM THENCE TO A SHEET FED BETWEEN THE BLANKET AND A COOPERATING IMPRESSION CYLINDER, A BLANKET SECURED TO SAID BLANKET CYLINDER HAVING THE IMAGE-RECEIVING SURFACE THEREOF COMPOSED OF POLYTETRAFLUOROETHYLENE.