US3508490A - Etch applicator for offset duplicating machine - Google Patents

Description

K. J. TONKIN ETAL ETCH APPLICATOR FOR OFFSET DUPLICATING MACHINE Original Filed July 24, 1964 April 28, 1970 2 Sheets-Sheet 1 IN v EN T0133 Kenneih J. 7bnkm A ril 2s, 1970 k. J. mm"; ETAL 3,508,490

ETCH APPLICATOR FOR OFFSET DUPLiCATING MACHINE Original Filed July 24, 1964 2 Sheets-Sheet 2 United States Patent 3,508,490 ETCH APPLICATOR FOR OFFSET DUPLICATIN G MACHINE Kenneth J. Tonkin, Glenview, and Richard R. Jeschke, Niles, Ill., assignors to A. B. Dick Company, Niles, Ill., a corporation of Illinois Original application July 24, 1964, Ser. No. 384,859, now Patent No. 3,431,841, dated Mar. 11, 1969. Divided and this application July 27, 1967, Ser. No. 656,485 Int. Cl. B411 25/10, 25/16 US. Cl. 101-147 2 Claims ABSTRACT OF THE DISCLOSURE An etch applicator for an offset duplicating machine, comprising an etch applicator pad mounted on a movable carriage which is engageable with a follower member to limit the movement of the applicator pad against the master cylinder, the follower member being in engagement with the eccentric shaft of the master cylinder whereby the carriage is caused to follow the shifting movement of the shaft, so that the corresponding shifting movement of the cylinder will not cause pressure variations between the cylinder and the pad.

This application is a division of our copending application, Ser No. 384,859, filed July 24, 1964, now Patent No. 3,431,841, issued Mar. 11, 1969.

This invention relates to duplicating machines and printing presses in general, and particularly to offset duplicating machines. Such offset machines normally use the lithographic process and involve a transfer or offsetting of the printed impression from the lithographic printing plate or master sheet to a rubber blanket, which in turn transfers the printed impression to a copy sheet.

The present invention relates more particularly to lithographic offset machines of the type equipped with an etch applicator mechanism, whereby an etching solution may be applied to the lithographic master sheet, in preparation for printing. The etch applicator may comprise a pad or other member which is supplied with the etching solution, and is adapted to be moved against the master cylinder, so that the etching solution will be applied to the master sheet. In many lithographic offset machines, the master cylinder is adapted to be separated from the blanket cylinder. When copy sheets are not being fed, such separation is brought about automatically, by a mechanism which oscillates the master cylinder, toward and away from the blanket cylinder. To cause such oscillation, the master cylinder often has a shaft with eccentric pivots.

The oscillation of the master Cylinder makes it difficult, if not impossible, to hold the etch applicator against the master cylinder with constant and uniform pressure. Thus, it is difficult to apply the etching solution evenly to the master sheet.

In accordance with the present invention, a follower member is provided which follows the oscillating movement of the master cylinder. The follower member is adapted to be engaged by the movable carriage which supports the etch applicator member. Thus, the follower member limits the movement of the carriage when the applicator member is moved against the master cylinder. When the master cylinder is oscillated, both the follower member and the carriage are caused to follow the oscillating movement, so that the pressure between the applicator member and the master sheet is maintained constant and uniform. Thus, the etching solution is applied uniformly and efficiently to the master sheet.

Various other objects, advantages and features of the present invention will appear from the following description, taken with the accompanying drawings, in which:

FIG. 1 is a diagrammatic side elevational view of a lithographic olfset duplicator which embodies the present invention.

FIG. 2 is a fragmentary side elevational view showing the etch applicator employed on the duplicator of FIG. 1.

FIG. 3 is a diagrammatic elevational section taken through the etch applicator.

FIG. 4 is a diagrammatic elevational section showing the etch applicator and the follower mechanism whereby the etch applicator follows the oscillating movement of the master cylinder.

The present invention will be described as embodied in a lithographic offset duplicator or printing press 40 illustrated diagrammatically in FIG. 1. This machine is of the three-cylinder type, having a master cylinder 42, a blanket or offset cylinder 44, and an impression cylinder 46. The master cylinder 42 is adapted to carry the master or printing sheet, which is usually made of paper or thin sheet metal, such as aluminum. Normally, the machine uses the lithographic process, so that certain image areas of the master are adapted to accept lithographic ink. The non-image areas of the master are adapted to accept water or a water-base moistening solution, which repels the ink.

The ink applied to the master on the master cylinder 42 is transferred or offset to the rubber blanket on the blanket cylinder 44. Copy sheets, usually made of paper, are fed between the blanket cylinder 44 and the impression cylinder 46, so that the inked image on the blanket will be transferred to the copy sheets. Offset duplicators of this general construction are well known to those skilled in the art.

Other features of the offset duplicator 40 are also illustrated in FIG. 1. As disclosed and claimed in our copending application, identified above, the machine is equipped with a master loading mechanism 48 whereby a new master may be loaded onto the master cylinder while the master cylinder continues to rotate at its normal speed. Thus, the master may be loaded onto the master cylinder without stopping the machine. A new master to be fed to the master cylinder 42 is placed on a master feed table 50. At the proper time, and under the control of the operator, the master is fed to the master cylinder by upper and lower feed rollers 52 and 54. The master is propelled between upper and lower guide plates 56 and 58. It will be seen that the lower guide plate 58 is an extension of the feed table 50.

The lithographic duplicator 40 is equipped with an etch applicator or mechanism 60 for applying an etching solution to the new master on the master cylinder 42, to prepare the master for the application of water and ink. In this case, the etch applicator 60 comprises a pad or wiper 62 which is movable between the sponge 64 and the surface of the master on the master cylinder 42. The sponge 64 serves as a reservoir to hold a supply of the etching solution. The illustrated pad 62 is hexagonal in shape so as toprovide six working surfaces which may be used successively to prolong the life of the pad. The etch applicator 60 is provided with an actuating lever 66 which may be swung clockwise to move the pad 62 between the sponge 64 and the master cylinder 42. As disclosed and claimed in said copending application, the master loading mechanism 48 is tied in with the etch applicator 60 in such a way that the actuation of the control lever 66 initiates the operation of the master loading mechanism. This arrangement insures that the etching solution will be applied to each new master, inasmuch as it is necessary to actuate the etch applicator in order to cause the new master to be loaded onto the master cylinder 42.

The duplicator 40 has a single master control lever 70 which operates a master or unified control mechanism, as disclosed and claimed in said copending application. The master lever 70 is employed by the operator to carry out all of the functions which are necessary to initiate and terminate the printing of copy sheets from any particular master. It will be seen that the control lever 70 has seven positions. A normal starting position is designated Neutral. The control lever 70 should be in the Neutral position when the master loading mechanism 48 is actuated to load a new master onto the master cylinder 42. After the etching solution has been applied to the new master and the etch control lever 66 has been returned to its initial position, the master lever 70 is advanced one step in a clockwise direction to the position designated Ink. In this position, ink and water are applied to the master.

The control lever 70 is then advanced another step to the position designated Image. This movement of the control lever causes the master cylinder 42 to move into engagement with the blanket cylinder 44, so that ink is transferred to the rubber blanket to develop an inked image on the blanket.

Next, the master control lever 70 is swung clockwise to the Feed position, and then is swung an additional amount to the Feed On position. Such operation of the control lever initiates the operation of the mechanism which feeds paper sheets between the blanket and impression cylinders 44 and 46. Such paper feed mechanisms are well known to those skilled in the art.

When the lever 70 is released, it does not stay in the Feed On position, but is resiliently returned to the Feed position, while the feed mechanism continues to operate. The lever 70 is left in the Feed position until the desired number of copy sheets have been printed. The master lever 70 is then returned manually in a counterclockwise direction, through the Image and Ink positions to the Neutral position. The return movement to the Image position terminates the operation of the paper feed mechanism, if such operation has not already been terminated by an automatic counter or a separate manual control. The return of the lever 70 to the Neutral position cuts oif the supply of ink and water to the master on the cylinder 42. The master cylinder is also separated from the blanket cylinder 44.

Next, the master lever 70 is moved in a counter-clockwise direction beyond the Neutral position to the next position, designated Eject. In this position, a master ejecting mechanism is actuated, so as to eject the master from the master cylinder 42 and into a receiving tray 82. The master is propelled into the tray 82 by upper and lower forwarding rollers 84 and 86. Further details )f the master ejecting mechanisms 80 are disclosed in said copending application.

The control lever 70 is then moved counter-clockwise through another step to the Wash position, so as to actuate a blanket washing mechanism which washes the ink off the rubber blanket on the blanket cylinder 44. Such blanket washers are well known to those skilled in :he art.

Finally, the master control lever 70 is returned in a :lockwise direction to the Neutral position, in preparation for the feeding of another new master to the master :ylinder 42. In moving between the Wash and Neutral positions, the lever 70' passes through the Eject posizion, but the control mechanism 72 is constructed and arranged so as to avoid actuating the master ejecting nechanism during the clockwise movement of the convrol lever.

The duplicator 40 is constructed so that all of the func- :ions of the machine may be carried out without stop- )ing the machine. Thus, it is desirable to change masters pi ly and to print the de ired number of copy sheets 4 from each successive master without stopping the machine at any time.

Other details of the etch applicator 60 are illustrated in FIG. 3. The control lever 66 is secured to a rotatable shaft which extends transversely across the machine. The hexagonal pad 62 is carried by a pair of arms 92 and 94 which are swingable about the axis of the shaft 90 but are secured to an elongated sleeve 96 which is rotatably mounted on the shaft 90. A spring 98 is provided to bias the pad 62 in a counter-clockwise direction toward the sponge 64. In this case, the spring 98 is of the coiled torsional type.

The control lever 66 is connected to the supporting arm 94 for the pad 62 in such a manner as to provide a certain amount of lost motion between the lever and the pad, so that the lever can travel farther than the pad. Thus, an arm 100 is secured to the shaft 90 and is fitted with a pin 102 which is movable in an arcuate slot 104 formed in the arm 94, which is on the far side of the machine as viewed in FIGS. 2 and 3. A coiled tension spring 106 is connected between the pin 102 and a pin 108 mounted on the arm 94. Clockwise movement of the control lever 66 causes corresponding movement of the arm 100. The pull of the tension spring 106 causes the arm 94 to swing with the arm 100 until the pad 62 engages the master cylinder 42, whereupon the lever 66 may be swung an additional distance, until the pin 102 reaches the lower end of the slot 104.

The hexagonal pad 62. is mounted on a roller 110 which is rotatably supported on the arms 92 and 94. When the pad 62 is moved between the sponge 64 and the master cylinder 42, the roller 110 is rotated relative to the arms 92 and 94 so that the pad 62 will present the same surface to the sponge 64 and the master cylinder 42. For this purpose, an arm 112 is secured to the roller 110 adjacent the supporting arm 94. The arm 112 is formed with a longitudinal slot 114 which slidably receives a stationary pin 116, mounted on a stationary supporting plate 118. Thus, the arm 112 is caused to swing about the pin 116 when the hexagonal pad 62 is swung between the sponge 64 and the master cylinder 42. It will be observed that the pin 116 is located approximately at the intersection of perpendicular lines extending from the sponge 64 and the master cylinder 42. In this way, the same surface of the pad 62 is presented to both the sponge and the master cylinder.

During the operation of the duplicator, the master cylinder 42 is repeatedly moved toward and away from the blanket cylinder 44 by an automatic mechanism which is under the control of the feed mechanism for the paper sheets. The automatic mechanism is operative to hold the master cylinder against the blanket cylinder when paper sheets are being fed. Such arrangements will be familiar to those skilled in the art. The shifting movement of the master cylinder 42, toward and away from the blanket cylinder 44 occurs during the operation of the etch mechanism 60 and tends to interfere with the smooth and efiicient application of the etching solution to the master.

However, the present etch mechanism is constructed to obviate any such interference. In the illustrated machine, the master cylinder 42 is rotatable about a supporting shaft 120 which does not rotate with the cylinder but is disposed eccentrically with respect to its supporting pivots 122. The master cylinder 42 is moved into and out of engagement with the blanket cylinder 44 by turning the pivots 122 through a relatively small angle.

In accordance with the present invention, an arrangement is provided whereby the etch applicator pad 62 will follow the shifting movement of the eccentric shaft 120, so that the pressure between the pad and the master will remain relatively constant. Thus, a follower bar 124 is slidably mounted on a frame plate 126 which constitutes the main left-hand frame plate of the machine. The lower end of the follower member 124 engages the eccentric shaft 120 so that the follower member moves up and down when the eccentric shaft is shifted up and down. The upper end of the follower member 124 is engaged by a stop member 128 which is movable with the etch applicator pad 62. In this case, the stop member 128 is in the form of a bar which 18 adjustably connected to the arm 112. Thus, an adjusting screw 130 is connected between flanges 132 and 134 on the upper ends of the arm 112 and the bar 128. It will be evident that the stop bar 128 may be adjusted upwardly and downwardly relative to the arm 112 and also relative to the pad 62. The adjustment of the stop bar 128 determines the extent to which the pad 62 may be moved downwardly before the stop bar 128 engages the upper end of the follower member 124.

The follower member 124 transmits the upward and downward movement of the eccentric shaft 120 to the stop bar 128 and thence to the pad 62, so that the pad is moved upwardly and downwardly with the shaft 120, This arrangement prevents any bouncing action between the pad 62 and the master cylinder 42. The pin 102 and the slot 104, together with the spring 106, accommodate the upward and downward movement of the pad 62.

It has already been indicated that the operation of the control lever 66 for the etch applicator 60 initiates the actuation of the master feeding mechanism 48, so that a new master sheet or printing plate is loaded onto the master cylinder 42. This tie-in is brought about by an additional arm 136 which is secured to the shaft 90 on which the control lever 66 is mounted. The arm 136 is formed with a finger 138 which is movable downwardly into engagement with a flange 140 on a control lever 142. The arrangement is such that the control lever 142 is swung counter-clockwise about its pivot 144 when the control lever 66 has been swung sufficiently in a clockwise direction to move the etch applicator pad 62 against the master cylinder 42. To provide for overtravel of the control lever 66 and the finger 138, the lever 142 is split into a main member 146, which is mounted on the pivot 144, and a left-hand arm member 148 on which the flange 140 is formed. The arm member 148 is connected to the main member 146 by a pivot 150. It will be seen that a spring 152 is connected between a pin 154 on the arm member 148 and an ear 156 on the main member 146. The spring 152 normally pulls the pin 154 against the main member 146. When the arm member 148 is swung counter-clockwise by the finger 138, the spring 152 causes the main member 146 to swing with the arm member 148. However, the spring 152 makes it possible for the movement of the arm member 148 to exceed that of the main member 146.

The split control lever 142 is adapted to initiate the operation of a control mechanism for the master loading device 48. Such control mechanism is disclosed and claimed in our above-identified copending application, to which reference may be had.

Various other modifications, alternative constructions and equivalents may be employed without departing from the true spirit and scope of the invention, as exemplified in the foregoing description and defined in the following claims.

We claim:

1. In a lithographic offset printing machine,

the combination comprising a stationary main frame,

a master cylinder for carrying a lithographic printing sheet,

a blanket cylinder rotatably mounted on said main frame for receiving an offset impression from said printing sheet,

said master cylinder having a shaft rotatably supporting said master cylinder,

said shaft having pivots rotatable on said main frame through a limited angle, said shaft being eccentric relative to said pivots, the limited angular rotation of said pivots being effective to cause bodily shifting movement of said master cylinder toward and away from said blanket cylinder,

an etch applicator member for applying an etching liquid to the printing sheet on said master cylinder,

source means for supplying etching liquid to said etch applicator member,

a swingable frame mounted on said main frame and supporting said etch applicator member for selective movement between said source means and said printing sheet on said master cylinder,

means biasing said swingable frame in a direction to move said etch applicator member to said source means,

selectively operable control means for swinging said swingable frame to bring said etch applicator member to said printing sheet,

a follower,

means on said main frame mounting said follower for movement along a predetermined path thereon,

said follower having a first portion engaging said eccentric shaft of said master cylinder for following the shifting movement of said shaft when said pivots are turned,

and a stop member connected to said swingable frame and movable therewith into and out of abutting engagement with said follower for limiting the movement of said etch applicator member toward said master cylinder,

said follower having a second portion engageable by said stop member,

said stop member being in engagement with said second portion of said follower when said etch applicator member is pressed against said printing sheet on said master cylinder,

said follower causing said etch applicator member to follow said shifting movement of said master cylinder so as to prevent said shifting movement from causing variations in the pressure between said etch applicator member and said printing sheet.

2. In a lithographic offset printing machine,

the combination comprising a stationary main frame,

a master cylinder for carrying a lithographic printing sheet,

a blanket cylinder rotatably mounted on said main frame for receiving an offset impression from said printing sheet,

said master cylinder having a shaft rotatably supporting said master cylinder,

said shaft having pivots rotatable on said main frame through a limited angle,

said shaft being eccentric relative to said pivots,

the limited angular rotation of said pivots being effective to cause bodily shifting movement of said master cylinder toward and away from said blanket cylinder,

an etch applicator member for applying an etching liquid to the printing sheet on said master cylinder,

source means for supplying etching liquid to said etch applicator member,

a carriage mounted on said main frame and supporting said etch applicator member for selective movement between said source means and said printing sheet on said master cylinder,

means biasing said carriage in a direction to move said etch applicator member to said source means,

selectively operable control means for moving said carriage to bring said etch applicator member to said printing sheet,

a follower,

means on said main frame mounting said follower for movement along a predetermined path thereon,

said follower having a first portion engaging said eccentric shaft of said master cylinder for following the shifting movement of said shaft when said pivots are turned.

and a stop member connected to said carriage and movable therewith into and out of abutting engagement with said follower for limiting the movement of said etch applicator member toward said master cylinder,

said follower having a second portion engageable by said stop member,

said stop member being in engagement with said second portion of said follower when said etch applicator member is pressed against said printing sheet on said master cylinder,

References Cited UNITED STATES PATENTS Janke 101-147 Peyrebrune 101-247 Gericke 101-442 Janke et al. 101147 Mestre 10l352 Tonkin et al 101--144 said follower causing said etch applicator member to 15 EDGAR S BURR, Primary E aminer

Images