US3039386A - Offset image forming head - Google Patents

Description

June 19, 1962 N. w. TRISLER OFFSET IMAGE FORMING HEAD 3 Sheets-Sheet 1 Filed Aug. 18, 1958 June 19, 1962 N. w. TRISLER OFFSET IMAGE FORMING HEAD 3 Sheets-Sheet 2 Filed Aug. 18, 1958 Maison WI Tiislqr' M 4 MM alworgg June 19, 1962 N. W.TR1SLER 3,039,386

OFFSET IMAGE FORMING HEAD Filed Aug. 18, 1958 3 Sheets-Sheet a I Ammwv Melsonw. Th'slev Witt W155 )2 M11 States Unite This invention is a novel image forming structure, or head, for offset duplicating and printing machines. The rolls used to place both moisture and ink on the image defining plate are carried in a form roll frame which permits a single lever to carry the entire assembly into and out of contact with the image forming plate selectively. For this reason, the number of levers with which the operator is concerned is reduced substantially. Also the form roll frame can be removed as a unit from the main head frame which facilitates cleaning when the color of ink to be used is changed or to permit repairs on the form roll assembly. The image forming head also incorporates novel ductor roll actuating mechanism in the form of twin, overtravelling, pivoting arms that automatically adapt themselves to variations in the sizes and positions of the rolls occasioned by the use of covered or molleton rolls and the unitary form roll assembly. This novel ductor arm structure permits a \greatly simplified linkage for driving the ductor arms as compared to the gear trains commonly used. Because it is simple, the mechanism may be duplicated on a single machine without great expense to provide positive actuation of both ends of the ductor rolls rather than driving only one end and allowing the other to follow as a result of the movement imparted to the first one. For this reason, moisture and ink are introduced into the system with great precision and consistency.

Accordingly, it is the main object of my invention to provide a novel image forming head for ofiset printing machines; one that:

(1) Provides very precise control over the quantities and distribution of moisture and ink applied to the image defining plate.

(2) Is generally of very simple construction which minimizes original cost and maintenance problems.

(3) Is easily cleaned and repaired.

(4) Employs only one control to turn on and off both ink and moisture in relation to the image defining plate.

While the specifically listed objects above are the principal ones of this invention, I intend to include as objects of this invention any advantages resulting from my structure that a person skilled in the offset printing art could visualize after reading this specification and examining the accompanying drawings that are briefy described below.

FIG. 1 is a side elevation of my image forming head with portions both deleted and broken away to show its novel structure clearly; broken lines show hidden parts and altered positions of visible ones. I

FIG. 2 is an enlarged, perspective view of the pivot portion of a ductor arm with a portion of the cover deleted to show internal structure.

FIG. 3 is a side elevation of the form roll assembly having both hidden and altered parts shown in broken lines.

FIG. 4 is an enlarged plan view of the form roll assembly and a fragment of the main head frame with portions of the rolls and control handle deleted to conserve space.

FIG. 5 is a perspective of the form roll assembly and the eccentric shaft that moves it into and out of engagement with the image defining plate on the plate cylinder.

FIG. 6 is a side elevation of the head from the opposite side from that shown in FIG. 1; broken lines are used to illustrate hidden parts; a portion of the latch is broken away to show an internal spring; conventional atent O ice parts are eliminated to retain clarity of the disclosure of novel parts.

FIG. 7 is a side elevation view of the form roll assembly, its stabilizing structure, control mechanism and latch; hidden parts are shown with broken lines.

FIG. 8 is a reduced side elevation of the ductor arm and fragments of the rolls and other structure intimately associated with it; solid lines show the final overtravelled position of the arm while broken lines show the position of the arm when the ductor roll remote from the push rod first engages another roll.

In general the invention may be seen in FIG. 1 to comprise an entire image forming head having the main frame 10 that is pivoted to the frame of the press as at 12, the press being designated 14. Image defining plates are secured to the plate cylinder 16 which may be brought into ink transferring relationship with the press blanket cylinder. Plate cylinder 16 which carries the image defining plates is rotatably mounted in frame 10 on the appropriately journalled shaft 18. When the image defining head is mounted ready for use, gear 20 that is secured to cylinder 16 engages the gear 22 that is secured to the offset or blanket carrying cylinder of the press and here represented by only a fragment of its gear. The image forming plate carrying cylinder 16 is brought into and out of ink transferring relationship with the blanket in the usual manner by means of an eccentric shaft 24 that engages both of a pair of such as the one 26 and is also pivoted in the press frame elements 14. The links are individually pivoted to the image head frame :10 by means of eccentrics such as the one 28 so that the effective length of the links may be adjusted to provide an even and correct amount of pressure between the plate and blanket cylinders for best ink transferring results. When properly adjusted, the eccentrics are locked in position frictionally by an appropriate means such as the cap screw 30 on eccentric 28. The machine as described so far is similar to many known machines in general operation if not in its details. I now turn to a description of the novel portions of my device which I believe to be patentable.

These novel portions include the mechanism for bringing the ductor rolls alternately into contact with the fountain rolls and transfer rolls that carry the material from the fountains to the plate, and the form roll assembly. For purposes of clarity, these two portions will be discussed separately before an attempt is made to describe their interaction.

Form Roll Assembly As shown clearly in FIGURES 4 and 5, the form roll assembly is a complete swbassembly that can be removed from the main image head frame 10. It consists of the end plates 32 and 34 that rotatably support between them on appropriate shafts 36 and 38 the form rolls 40 and 42. Slots are provided in the end plates to support removably the covered or molleton roll 44 and the oscillator 46. Thumb screws such as the ones 43 and 45 frictionally hold the molleton 44 down on the form roll 42 with whatever degree of pressure desired. In FIG- URES 1, 3, 6 and 7, the oscillating roll or oscillator 46 may be seen to contact both of the form rolls 40 and 42. It is important that oscillator 46 makes this dual contact. When it does not, and cylinder 16 is rotating in the direction indicated by the arrows in FIGURES 1 and 6, ink from form roll 42 is carried back into molleton roll A 44 in undesirable quantities at least as compared to 44. With oscillator 46 positioned as shown in the drawings, however, the cylinder 16 should always rotate as indicated by the arrows. I cannot explain with certainty why this phenomenon occurs, consequently I only report it.

The oscillator 46 serves another function when the cylinder 16 rotates as indicated by the arrows. Given the arrow direction of rotation for the mechanism, form roll 42 is the last form roll to deposit ink on the plate before it in turn deposits its image on the blanket. Since molleton 44 will impress its nap pattern on form roll 42, the pattern may show up as irregularities of ink deposited on the plate unless the pattern is dissipated. Wiping out this nap pattern on form roll 42 before it contacts a plate on cylinder 16 is the second function of the oscillator 46.

A third function performed by the interaction of the form roll 42 and oscillator 46 is to trap excess moisture from the =mo-lleton 44 placed on form roll 42. The oscillator and the form roll together squeeze excess moisture off the surface of molleton 42 and roll it back in the form of a bead where these two rolls come together. An alert operator can observe such a condition before it gets entirely out of hand and take the necessary steps to correct it.

A tie rod 48 holds the two end plates together but not rigidly so. For- m roll frame 32, 34 and 48 is perhaps best described as loose jointed to permit it to adapt itself to the requirements of the rest of the structure in seating down on the plate when ink and moisture are being transferred to it. Through apertures in the end plates 32-64, an eccentric shaft 50 extends and which serves the dual purpose of holding the form roll frame within the main frame as shown in FIG. 4 and also to provide a means for moving the form roll frame to and from the plate cylinder 16. When the shaft is acting to hold the form roll frame within the main frame 10 as shown in FIG. 4, it extends through pierced shaft carriers 52-54 that may be moved to and from the plate cylinder to adjust the amount of pressure or stripe, as it is called, that the form rolls place on the plate when the handle of shaft 50 is turned down to carry the form rolls 4042 into contact with the plate on cylinder 16. They are shown here as being eccentrically pierced and rotatably mounted which is the simplest form of carrier that could be devised to permit the vertical adjustment of the entire form roll assembly. The carriers are provided with the collars 56-58 by means of which the carriers are frictionally held in adjusted position by suitable means such as the cap screws 60 in FIG. 4 and 62 in FIG. 6. On the shaft 50 is a latch ring 64 that carries several spaced bosses designated 66, 68 and 70 in FIGURES 6 and 7. These bosses engage the spring loaded catch '72 and the stop screw 74 in latch block 76 to both latch and limit the movement of shaft 50. Latch ring 64 is secured to shaft 50 by means of a set screw so that it may be appropriately positioned after the machine is correctly adjusted to achieve the desired results. Oap screw 62 serves both to secure the carrier 54 and the latch block 7 6 in position, the former Iby clamping the latter against it.

Eccentric shaft 50 has a collar 65 on it near the latch 10. Adjustable stops such as the threaded screws 8486 determine the position of the form roll frame when the shaft 50 is turned far enough in either direction to carry the form roll frame back against the stops. As will be seen by comparing FIGURES 6 and 7, the shaft 50 is turned through more than 180 degrees of rotation when the form roll frame is moved from one extreme of movement to the other. In both cases, therefore, the form roll frame comes to rest with the end plates 32-34 abutting against the screws 84-86 when the machine is correctly adjusted. in this manner, the form roll frame is stabilized against tipping even when raised from the plate cylinder as well as when the rolls pass over the open portion of the plate cylinder in which the usual plate securing mechanism is mounted. Thus although the single eccentric shaft 50 carries the form roll frame assembly into and out of contact with the plate cylinder, the assembly is stabilized by the stops for effective operation. Screws 84-86 are provided with the usual locking jarn b nuts 33 and 35. I turn now to a description of the ductor roll actuating mechanism.

Ductor Roll Actuating Mechanism Within the frame 10 are the usual ink fountain roll 88 and fountain 00. Below the ink fountain roll and also rotatably mounted in the frame 10 is the idler 92. A transfer roll, preferably an oscillating roll, 94 contacts the idler 92 and the rear form roll 40 when the form roll assembly is in the machine. In order to transfer ink from the fountain roll to the idler 92 and through the oscillating roll 94 to the form roll assembly, the usual ductor roll 96 is moved back and forth between them. The frame 10 also carries the usual moisture or etch fountain 98 in which the customary fountain roll 100 is rotatably mounted. Moisture is supplied from the usual vacuum controlled reservoir 102. As is shown clearly in FIGURES 1, 6 and 8, a moisture ductor roll 104 is movably mounted between the moisture fountain roll 100 and the molleton roll 44 of the form roll assembly. Appropriate linkage that is thought to be non-inventive and therefore not shown drives the customary ratchet type rotation control for both of the fountain rolls.

The mechanism for moving the ductor rolls is shown clearly in FIGURES l, 6 and 8 to be a pair of ductor arms 106 and 108 that are pivoted to the frame 10 as at 110 and 112. Suitable bearing blocks such as the ones 114 and 116 on arm 106 support the ends of the ductor rolls. Suitable means are provided also for removing the ductors from the ductor arms at times, but this structure is neither illustrated nor described as it is not claimed to be inventive. The arms 106 and 108 are on the outside of the frame 10 and the ductor rolls are inside. The ink ductor roll bearing block such as 114 reaches through the opening 113 to engage the ink ductor and support it. An opening similar to 113 and designated is provided in the other side of the frame 10.

In order to acquire fresh ink or moisture as the case may be, each ductor must be brought into contact with its fountain roll while it is turning. As seen in FIG- URES 1, '6 and 8, cams 118 and 120 are secured to the shaft 18 of the plate cylinder 16 and rotate with the cylinder. The cams will be seen to be cut to provide lift during about one half of a revolution and not during the other half. Pivoted to the frame at 122 is the cam follower arm 124, which extends out over the cam 118. A push rod 126 fits into a hole in the cam follower 124 and extends up to a depression or dimple 128 in ductor arm 106. The adjusting and jamb nuts 125 and 127 respectively permit the adjustment of the effective length of push rod 126. A resilient member such as spring 130 is secured to a boss 132 fixed in frame 10 and to cam follower 124 which yieldingly holds the push rod 126 in engagement with the ductor arm 106. Another and substantially more powerful resilient member such as the coil spring 134 exerts a downward force yieldingly on the end of the ductor arm 106 that carries the ink ductor roll. When the cam 118 moves the cam follower 124 up, spring 134 yields to allow the ink ductor 96 to move up against the ink fountain roll 88. As arm 106 is thus pivoted, moisture ductor 104 is pivoted down to contact the molleton roll 44. On the other hand, when the cam 118 is in the broken line position in FIG. 1, the cam follower is dropped down to the broken line position, and spring 134 pulls the ink ductor 96 down into contact with the idler 92. If the spacing between the ink fountain roll 88 and its associated idler roll 92 and between the moisture fountain roll 100 and the molleton roll 44 remained constant, the ductor arms 106 and 108 would need only to pivot precisely to bring both ductors into contact with their respective associated rollers during any given pivoting action of the arms 106 and 108. We have already seen, however, that the molleton roll 44 moves up and down with the form roll assembly in which the molleton roll is mounted in turning the moisture and ink form rolls into and out of contact with the plate cylinder 16. Thus the distance between the moisture fountain roll 100 and the molleton roll 44 will vary from the on to off position. Furthermore, as the cloth covers on the molleton roll 44 and the moisture ductor roll 104 become packed down in use and, therefore, thinner; there is a further alteration in the amount of movement necessary to carry the ductor roll 104 from a good solid contact with the fountain roll 100 to an equally positive contact with the molleton roll 44. 'In order to make sure the moisture roll known as the ductor will travel far enough to make these essential contacts under all conditions, it is necessary for the arm 106 to pivot farther under some circumstances than others. For this reason some method of ductor arm overtravel must be provided when distances are minimum to assure suflicient movement when distances are maximum. A means of allowing for this overtravel at times is illustrated in detail in FIGURES 2 and 8, the latter illustrating the action that occurs when overtravel is needed. As seen in FIG. 2, the center of the ductor arm 106 is provided with a hollow housing 136 into which is secured a rubber bushing 138 which has mounted in its approximate center a bearing 139. A spacer 140 is a pivoting fit within the bearing 139. This spacer is slightly longer than the housing 136 is thick, so that when the cap screw that extends through the spacer and threads into the frame of the machine is tightened, the washers on either side of the housing 136 such as the washers 142 and 144 are held in close relationship to the housing without clamping it. The arm 106 is free to pivot, therefore, but at the same time is held upright or in a single plane. The spacing of the washers 142 and 144 also permits the movement that is necessary to allow the arm to overtravel. As shown in FIG. 8, the rubber bushing in the housing 136 allows the arm 106 to shift to a limited extent relative to the cap screw 110 as well as to pivot about it. As shown in that figure in broken lines, the moisture ductor engages the moisture roll before the ink ductor has reached the idler 92. This condition might exist when the moisture ductor is new and has a cover on it with a thick nap. Under these conditions the ductor roller would be somewhat larger in diameter than it will have after it has been used for awhile and the cloth cover has been packed down. When pivoting of the arm is inhibited by the moisture ductor coming into contact with the fountain roll as shown in FIG. 8, however, the moisture ductor roll becomes a fulcrum point, and continued pressure by the spring 134 will cause the arm 106 to overtravel and assume the final position shown in solid lines in that figure. The arm has overtravelled by distorting the rubber bushing 138. One may regard the rubber bushing as being secured to the frame 10 and thus considered would be providing a yielding pivot secured to the frame, or one may think of the bushing as secured to the ductor arm and, therefore, a yielding means within the arm. In either case, the structure seems to be correctly described as an overtravelling arm. There may well be other structures that could be evolved to accomplish this movement and thereby allow the necessary overtravel. The form of ductor arms shown is shown and described as being the simplest one that applicant has evolved. Since the cams 118 and 120 are the same and are identically secured to the shaft 18, it is clear that both of the ductor arms will be pivoted precisely the same. Hence both ends of the ductor arm will be carried up or down together and to the same extent. The ductors will contact the fountain rolls all along their respective lengths at about the same time, therefore, in distinction to systems sometimes used with this type of equipment in which only one end of the ductor rolls are moved positively and the other merely follows along sometimes with a noticeable lag. By positively driving both ends of the ductor rolls, I achieve very even and consistent distribution of both ink and moisture.

The parts associated with ductor arm 108 in FIG. 6 are the counterparts of parts carrying the same name and described in connection with ductor arm 106. They may be identified in the drawings as follows: cam follower 146, cam follower pivot 148, push rod 150, cam follower retaining spring 152, spring boss 15'4, ductor arm return spring 156, ductor arm bearing blocks 158' and 160, ductor arm housing 162, and washers 164 and 166.

I have described and shown a practical and I believe most desirable, though not exclusive practical embodiment of my invention. I now point out and claim with the particularity required by statute the structure that I believe to be inventive.

I claim:

1. In an image forming head for offset printing; a frame; a plate cylinder rotatably supported in said frame; an ink fountain and fountain roll operatively secured to said frame; a moisture fountain and fountain roll operatively secured to said frame; an ink roll near said ink fountain roll; a form roll assembly within said frame; a moisture roll in said form roll assembly; means for moving said form roll assembly into and out of contact with a plate mounted on said plate cylinder; stabilizing means secured to said frame and engaging said form roll assembly in at least two positions; two ductor arms pivoted to said frame; overtravel means operatively associated with said ductor arms and said frame; an ink ductor roll and a moisture ductor roll rotatably carried between opposed ends of said ductor arms; and means for pivoting said ductor arms in both directions with sufficient force to cause overtravel of said ductor arms; said ink ductor roll contacting said ink fountain roll approximately when said moisture ductor roll is contacting said moisture roll in said form roll assembly and said ink ductor roll contacting said ink roll near said ink fountain roll approximately when said moisture ductor roll is contacting said moisture fountain roll.

2. The offset printing structure ductor mechanism of claim 1 in which said means for pivoting said ductor arms are cams rotatably secured to said frame; means for driving said cams at the same rate as said plate cylinder; cam followers pivoted to said frame and engaging said cams; push rods engaging said cam followers and said arms; and springs secured to said arms and said frame and yieldingly urging said arms toward said push rods.

3. In an oifset printing ductor mechanism; a frame; two yielding pivot means secured to said frame; two ductor arms mounted on said yielding pivot means; two ductor rollers carried by the ends of said ductor arms; four other rollers rotatably mounted in said frame two of said four other rollers on opposite sides of one of said ductor rollers; the other two of said four other rollers on opposite sides of the other of said ductors and means for pivoting said ductor arms to cause both ductor rollers to contact other rollers in both directions of pivoting; at least one of said four other rollers having its axis of rotation moved in the course of operation; said means for pivoting being of sufficient force to displace said yielding pivot means.

4. In an offset printing machine form roll assembly;

a main frame; a plate cylinder rotatably mounted directly in said main frame; a form roll frame movable within said main frame; a single means for securing said form roll frame within said main frame and for moving said form roll frame relative to said main frame; the form rolls in said form roll frame being moved into and out of contact selectively with said plate cylinder by said single means; and means secured to one of said main and form roll frames and engaging the other to stabilize said form roll frame relative to said main frame.

5. In an offset printing form roll assembly for use with an offset printing machine having a main frame; shaft carriers secured to said main frame; a form roll frame having shaft receiving apertures fitting Within said main frame; an eccentric shaft extending through said shaft carriers and the apertures of said form roll frame and rotatable therein; whereby said form roll frame is moved in relation to said main frame by turning said eccentric shaft; and means secured to said main frame and engaging said form roll frame to stabilize said form roll frame in at least two different positions; said form roll frame being held in said main frame solely by said eccentric shaft.

6. The offset printing form roll assembly of claim in which a plate cylinder is rotatably mounted in said main frame; and means secured to said shaft carriers for adjusting them to and from said plate cylinder selectively; said stabilizing means operating near the extremes of movement of said form roll frame imparted to it by said eccentric shaft.

7. In an offset printing ductor mechanism; a frame; an ink fountain secured to said frame; an ink fountain roll rotatably mounted on said frame in operative engagement with said ink fountain; an ink roller spaced from said ink fountain roller and rotatably secured to said frame; a moisture fountain secured to said frame; a moisture fountain roller rotatably secured to said frame in operative relation to said moisture fountain; a moisture receiving roller spaced from said moisture fountain roller; a single pair of ductor arms pivoted intermediate their ends to said frame between said ink rollers at one extreme and said moisture rollers at the other and having their ends extending adjacent to said rollers; an ink ductor roll carried between ends of said single pair of ductor arms and positioned between said ink fountain roller and said ink roller; a moisture ductor roll carried by the other ends of said single pair of ductor arms and positioned between said moisture fountain roller and said moisture receiving roller; means secured to said frame for pivoting said ductor arms; and overtravel means operatively associated with the pivotal connection of said ductor arms to said frame permitting continued movement of said ductor arms after either ductor roller has contacted another roller; whereby each ductor roller will always contact another roller at each extreme of pivoting of said single pair of ductor arms.

8. The olfset printing ductor mechanism of claim 7 in which said overtravel means comprises; a hollow housing on each of said ductor arms; a pierced resilient member in each of said hollow housings; and pivots extending through said pierced resilient members and fixed in said frame.

9. The offset printing ductor mechanism of claim 3 in which said yielding pivot means can yield in all directions.

References Qited in the file of this patent UNITED STATES PATENTS 1,496,455 Dudley June 3, 1924 1,524,816 Dalby Feb. 3, 1925 2,033,950 Morse Mar. 17, 1936 2,083,542 Barber June 15, 1937 2,306,044 Davidson Dec. 22, 1942 2,424,606 Engler July 29, 1947 2,547,471 Janke Apr. 3, 1951 2,641,999 Jackson June 16, 1953 2,838,301 Strumbos June 10, 1958 2,915,306 Hickman Dec. 1, 1959 2,915,970 Mestre Dec. 8, 1959

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