Web apparatus with variable repeat interval

What is claimed as the invention is:

1. Apparatus comprising means whereby a web of indeterminate length, drawn from a supply roll, is guided for lengthwise forward movement along a path through an impression zone that has front and rear ends which are spaced apart along said path and to a delivery zone, a rotatable delineating cylinder cooperating with a rotatable opposing cylinder to define a nip in said impression zone through which the web passes and at which the delineating cylinder produces uniform impressions on the web at uniform repeat intervals along it, said delineating cylinder having a cutout in its periphery to be out of contact with the web during an idle phase of each cycle of its rotation in which said cutout is juxtaposed to said opposing cylinder, the remainder of each said cycle being an advancing phase during which the delineating cylinder can produce an impression on the web, and drive means for rotating the delineating cylinder at a predetermined peripheral speed, said apparatus being characterized by:

A. a front pair and a rear pair of feed rollers, each said pair defining a nip through which the web passes to be fed forward by the pair, one feed roller of each said pair being rotatably driven from said drive means at a substantially steady rate such that the length of web fed forward by the pair during each said cycle is equal to the length of a repeat interval,

(1) said rear pair being located along said path between the supply roll and the rear end of the impression zone, and

(2) said front pair being located along said path between the front end of the impression zone and the delivery zone; and

B. front and rear cyclically operating means,

(1) each comprising

(a) a control roller about which the web is looped,

(b) a carrier by which the control roller is carried for cyclical bodily movement transverse to its length whereby the loop of web around the control roller is alternately increased and permitted to decrease, and

(c) transmission means drivingly connecting said carrier with said drive means and whereby said carrier is actuated to carry the control roller through a cycle of its bodily movement during each said cycle of the delineating cylinder,

(2) said front cyclically operating means being located along said path between said front end of the impression zone and said front pair of feed rollers, for constraining web in the impression zone to move forward at a speed equal to said peripheral speed all during each advancing phase and allowing the web in that zone to move rearward during each idle phase, and

(3) said rear cyclically operating means being located along said path between said rear pair of feed rollers and the rear end of the impression zone, for allowing web in that zone to move forward all during each advancing phase and constraining web in that zone to move rearward through a predetermined distance during each idle phase.

2. The apparatus of claim 1,

C. wherein each said cyclically operating means has a fixed axis about which its carrier is rotatable and is further characterized by

(1) control roller supporting means mounting its control roller on its carrier eccentrically to its fixed axis to be moved bodily in an orbit about that axis by rotation of the carrier, and

(2) means for adjustingly shifting said control roller supporting means radially relative to the carrier, towards and from said fixed axis, to adjustably vary the radius of said orbit and thereby adjustably vary the distance through which web in the impression zone is moved rearward during each idle phase; and

D. further characterized by a variable ratio driving transmission connected between said drive means and said one feed roller of each pair of feed rollers, for adjustably varying the length of web fed forward by the feed rollers during each cycle of rotation of the delineating cylinder.

3. The apparatus of claim 2 wherein the carrier of each said cyclically operating means is freely rotatable about its fixed axis and each said transmission means comprises:

(1) a driver axially adjacent to the carrier and confined to rotation coaxially therewith, said driver being connected with said drive means to be rotated thereby in unison with rotation of the delineating cylinder,

(2) fixed cam means axially adjacent to said driver defining a cam track substantially contained in a plane normal to said fixed axis and extending around the same, and

(3) a drive link having

(a) a pivotal connection with said driver to be confined to swinging relative to the driver about a pivot axis which is spaced from and substantially parallel to said fixed axis,

(b) a first arm extending outwardly from said pivotal connection and having at its outer end a cam follower engaged with said cam track to be swung about said pivot axis during rotation of the driver by differences in the distance between said fixed axis and successive points along the cam track, and

(c) a second arm extending outwardly from said pivotal connection and rigid with said first arm to be swingable therewith, said second arm having at its outer end a connection with the carrier whereby the latter is constrained to rotate through one revolution for each revolution of the driver but is rotationally accelerated and decelerated relative to the driver by swinging of said arms.

4. Apparatus comprising means whereby a web of indeterminate length is guided for lengthwise forward movement along a path through an impression zone that has front and rear ends which are spaced apart along said path and to a delivery zone, a rotatable delineating cylinder cooperating with a rotatable opposing cylinder to define a nip in said impression zone through which the web passes and at which the delineating cylinder produces uniform impressions on the web at uniform length repeat intervals along it, said delineating cylinder having a cutout in its periphery to be out of contact with the web during an idle phase of each cycle of its rotation in which said cutout is juxtaposed to said opposing cylinder, the remainder of each said cycle being an advancing phase during which the delineating cylinder can produce an impression upon the web, and drive means for rotating the delineating cylinder at a predetermined peripheral speed, said apparatus being characterized by:

A. a pair of feed rollers that define a further nip through which the web passes, said feed rollers being located along said path between the front end of the impression zone and the delivery zone;

B. transmission means connecting said drive means with one of said feed rollers, said transmission means

(1) having an adjustably variable ratio and

(2) providing for rotatably driving said one feed roller from said drive means at a substantially steady rate such that the length of web fed forward by the pair of feed rollers during each said cycle is equal to the length of one of said repeat intervals; and

C. front and rear cyclically operating means

(1) each having a fixed axis and comprising

(a) a control roller about which the web is looped,

(b) a carrier element freely rotatable about said fixed axis,

(c) control roller supporting means mounting the control roller on said carrier element eccentrically to said fixed axis so that rotation of the carrier element moves the control roller bodily, transversely to its length, in an orbit whereby the loop of web around the control roller is alternately increased and permitted to decrease,

(d) means for adjustingly shifting said control roller supporting means radially relative to the carrier element, towards and from said fixed axis, to adjustably vary the radius of said orbit,

(e) a driver element axially adjacent to the carrier element and confined to rotation coaxially therewith, said driver element being connected with said drive means to be rotated thereby in unison with rotation of the delineating cylinder,

(f) fixed cam means axially adjacent to said driver element, having a cam track substantially contained in a plane normal to said fixed axis and extending around the same, and

(g) a drive link having

(i) a pivotal connection with one of said elements to be confined to swinging relative to the same about a pivot axis which is spaced from and substantially parallel to said fixed axis,

(ii) a first arm extending outwardly from said pivotal connection and having at its outer end a connection with the other of said elements that is confined to radial motion relative thereto so that swinging of said arm in opposite directions about said pivotal connection effects rotational acceleration and deceleration, respectively, of the carrier element relative to the driver element, and

(iii) a second arm extending outwardly from the connection between the driver element and the drive link and having at its outer end a cam follower engaged with said cam track whereby the drive link is swung about said pivotal connection during rotation of the driver element by differences in the distance between said fixed axis and successive points along the cam track,

(2) said front cyclically operating means being located along said path between the front end of the impression zone and said pair of feed rollers, and

(3) said rear cyclically operating means being located along said path in rearwardly spaced relation to the rear end of the impression zone.

5. The apparatus of claim 4, wherein a supply roll stand for supporting a supply roll from which web is drawn is spaced rearwardly along said path from said rear cyclically operating means, further characterized by:

D. a second pair of feed rollers defining a third nip through which the web passes, located along said path between said supply roll stand and said rear cyclically operating means, one of the feed rollers of said second pair being rotatably driven from said transmission means for rotation in unison with said one feed roller of the first mentioned pair.

6. The apparatus of claim 4, wherein said transmission means is a variable ratio planetary transmission comprising:

(1) a driving sun gear rotatably driven by said drive means,

(2) a driven sun gear coaxial with said driving sun gear and from which said one feed roller is rotatably driven,

(3) a cage coaxial with said sun gears and rotatable relative to both of them,

(4) a plurality of planet gears carried by said cage and confined to rotation relative thereto, each of said planet gears having meshing engagement with both of said sun gears, and

(5) a variable speed electric motor drivingly connected with said cage for rotating the same.

7. Apparatus comprising means whereby a web of indeterminate length is guided for lengthwise forward movement along a defined path, a rotatable delineating cylinder cooperating with a rotatable opposing cylinder to define a nip in said path through which the web passes and at which uniform impressions are produced on the web at uniform but adjustably variable repeat intervals along it, said delineating cylinder having a cutout in its periphery to be out of contact with the web through an idle phase in each cycle of its rotation during which said cutout is juxtaposed to said opposing cylinder and being cooperable with said opposing cylinder to produce an impression upon the web during an advancing phase in the remainder of each said cycle, drive means for rotating the delineating cylinder at a predetermined peripheral speed, at least one pair of feed rollers along said path whereby web is fed forward through a distance equal to the length of one of said repeat intervals during each said cycle, and front and rear cyclically operating means, respectively spaced forwardly and rearwardly along said path from said nip, cooperable with one another and with said feed rollers to advance web forwardly through said nip at a lengthwise speed equal to said peripheral speed through the advancing phase of each said cycle and whereby web is moved an adjustably variable distance rearwardly through said nip during each said idle phase, said apparatus being characterized by each said cyclically operating means comprising:

A. a control roller which extends transversely across said path and about which the web is looped;

B. a carrier element freely rotatable about a fixed axis;

C. control roller supporting means mounting the control roller on said carrier element eccentrically to said fixed axis so that rotation of the carrier element moves the control roller bodily, transversely to its length, in an orbit whereby the loop of web around the control roller is alternately increased and permitted to decrease;

D. means for adjustingly shifting the control roller supporting means radially relative to the carrier element, towards and from said fixed axis, to adjustably vary the radius of said orbit;

E. a driver element axially adjacent to the carrier element and confined to rotation coaxially therewith, said driver element being connected with said drive means to be rotated thereby in unison with rotation of the delineating cylinder;

F. fixed cam means axially adjacent to said driver element having a cam track substantially contained in a plane normal to said fixed axis and extending around the same; and

G. a drive link having

(1) a pivotal connection with one of said elements to be confined to swinging relative to the same about a pivot axis which is spaced from and substantially parallel to said fixed axis,

(2) a first arm extending outwardly from said pivotal connection and having at its outer end a connection with the other of said elements that is confined to radial motion relative thereto so that swinging of said arm in opposite directions about said pivotal connection effects rotational acceleration and deceleration, respectively, of the carrier element relative to the driver element, and

(3) a second arm extending outwardly from the connection between the driver element and the drive link and having at its outer end a cam follower engaged with said cam track whereby the drive link is swung about said pivotal connection during rotation of the driver element by differences in the distance between said fixed axis and successive points along the cam track.

8. The apparatus of claim 7, wherein there are front and rear pairs of feed rollers along said path, the front pair of feed rollers being spaced forwardly along said path from the front cyclically operating means and the rear pair of feed rollers being spaced rearwardly along said path from the rear cyclically operating means, further characterized by:

a variable ratio transmission through which one of the feed rollers of each said pair is driven from said drive means at a substantially steady rate which is adjustably variable and which is equal to the length of one of said repeat intervals per cycle of rotation of the delineating cylinder.

9. Apparatus comprising means whereby a web of indeterminate length is guided for lengthwise forward movement along a defined path, a rotatable delineating cylinder cooperating with a rotatable opposing cylinder to define a nip in said path through which the web passes and at which uniform impressions are produced on the web at repeat intervals along it that have uniform but adjustably variable lengths, said delineating cylinder having a cutout in its periphery to be out of contact with the web through an idle phase in each cycle of its rotation during which said cutout is juxtaposed to said opposing cylinder and being cooperable with said opposing cylinder to produce an impression upon the web during an advancing phase in the remainder of each said cycle, drive means for rotating the delineating cylinder at a predetermined peripheral speed, at least one pair of feed rollers along said path whereby web is fed forward through a distance equal to the length of one of said repeat intervals during each said cycle, and front and rear cyclically operating means, respectively spaced forwardly and rearwardly along said path from said nip, cooperable with one another and with said feed rollers to move web at said nip forwardly all during said advancing phase of each cycle and to move web at said nip rearwardly through an adjustably variable distance during each said idle phase, said apparatus being characterized by each said cyclically operating means comprising:

A. a control roller which extends transversely across said path and about which the web is looped;

B. a carrier element rotatable about a fixed axis;

C. control roller supporting means mounting the control roller on said carrier element eccentrically to said fixed axis so that rotation of the carrier element moves the control roller bodily, transversely to its length, in an orbit about said fixed axis whereby the loop of web about the control roller is alternately increased and permitted to decrease;

D. means for adjustingly shifting the control roller supporting means radially relative to the carrier elements towards and from said fixed axis, to adjustably vary the radius of said orbit and thus vary the distance through which web at said nip is moved rearward during each said idle phase; and

E. driver means connected between said drive means and the carrier element for rotating the carrier element through a cycle of its revolution during each said cycle of the delineating cylinder and whereby the rotational speed of the carrier element is so varied from part to part of its said cycle that all during said advancing phase the web at said nip is maintained at a forward speed equal to the peripheral speed of the delineating cylinder and during said idle phase the web at said nip is smoothly decelerated and accelerated for its rearward movement and for resumption of forward movement.

10. The apparatus of claim 9 wherein said driver means comprises:

(1) stationary means defining a cam track substantially contained in a plane normal to said fixed axis and which extends around said fixed axis;

(2) a driver element between said stationary means and said carrier element, said driver element being

(a) rotatable about said fixed axis and

(b) connected with said drive means for rotation in unison with the delineating cylinder; and

(3) a drive link having

(a) a pivotal connection with one of said elements to be confined to swinging relative to the same about a pivot axis which is spaced from and substantially parallel to said fixed axis,

(b) a first arm extending outwardly from said pivotal connection and having at its outer end a connection with the other of said elements that is confined to radial motion relative thereto so that swinging of said arm in opposite directions about said pivotal connection effects rotational acceleration and deceleration, respectively, of the carrier element relative to the driver element, and

(c) a second arm extending outwardly from the connection between the driver element and the drive link and having at its outer end a cam follower engaged with said cam track whereby the drive link is swung about said pivotal connection during rotation of the driver element by differences in the distance between said fixed axis and successive points along the cam track.

11. The apparatus of claim 9, wherein there are front and rear pairs of feed rollers along said path, the front pair of feed rollers being spaced forwardly along said path from the front cyclically operating means and the rear pair of feed rollers being spaced rearwardly along said path from the rear cyclically operating means, further characterized by:

a variable ratio transmission through which one of the feed rollers of each said pair is driven from said drive means at a substantially steady rate which is adjustably variable and which is equal to the length of one of said repeat intervals per cycle of rotation of the delineating cylinder.

Description Submit all comments and votes

FIELD OF THE INVENTION

This invention relates to apparatus that comprises a rotating cylinder whereby uniform impressions are made on a web of indeterminate length at uniform repeat intervals along the web, as in printing, offset lithography and rotary die cutting; and the invention is more particularly concerned with apparatus of that character which provides for steplessly adjustable variation of the length of the repeat interval without the need for changing gear sets to change repeat interval length.

BACKGROUND OF THE PRIOR ART

There are several processes such as printing, offset lithography and rotary die cutting in which a web of indeterminate length, drawn off of a supply roll, is moved lengthwise forward through an impression zone at which it passes through a nip defined by a delineating cylinder that contacts one surface of the web and an opposing cylinder that engages its opposite surface. The delineating cylinder, which carries means for transferring ink or the like to the web, or for cutting or scoring the web, rotates in step with forward movement of the web to make uniform impressions upon it at regular repeat intervals along its length.

In many cases, apparatus for performing these processes should be adjustable for changing the length of the repeat interval, to be capable of running different jobs. An expedient for accomplishing such adjustability is broadly disclosed in each of U.S. Pat. No. 2,758,541 to R. A. Tison (1956), No. 2,845,021 to Pinckert et al (1958), and No. 3,756,149 to T. D. Bishop (1973). In these, the delineating cylinder has a cutout or reduced radius peripheral portion that extends around a part of its circumference, to be out of contact with the web through the fraction of each revolution during which the cutout is juxtaposed to the opposing cylinder. This fraction of a revolution can be considered an idle phase in the rotational cycle of the delineating cylinder. Through an advancing phase which constitutes the remainder of its cycle and during which the delineating cylinder can be in contact with the web, the forward speed of the web is maintained equal to the peripheral speed of that cylinder and the web moves forward though an invariable advancing distance. During the idle phase the web is moved rearward through a decremental distance which is less than the advancing distance. The difference between those distances is the repeat interval length, which can be changed if the decremental distance can be changed.

In the apparatus of the Tison patent, the web is trained in a loop around each of a pair of control rollers, one upstream from the delineating cylinder nip and the other downstream from it. Those control rollers are in turn carried by a frame which reciprocates forwardly and rearwardly to increase and decrease the length of web in each loop. The frame moves forward during the advancing phase of the delineating cylinder cycle, increasing the loop around the downstream control roller and permitting the loop upstream from the nip to decrease in size, thus moving the web through the advancing distance. Rearward movement of the frame during the idle phase effects an opposite change in the sizes of the loops and thus tends to move the web through a decremental distance equal to the advancing distance. However, during rearward movement of the frame, intermittently driven feed rollers downstream from the frame draw the web forward through a distance equal to the repeat interval length. One of the feed rollers carries a coaxial pinion, to be rotatably driven by endwise movement of a ratchet-toothed rack; and the rack, in turn, has one end connected to a rotating eccentric to be reciprocated lengthwise by rotation of the eccentric, which is synchronized with rotation of the delineating cylinder and reciprocation of the frame. The feed rollers are apparently rotated only during rearward movement of the frame but maintain their grip on the web, without rotation, during forward movement of the frame.

With the apparatus as disclosed by Tison, the web is drawn off of the supply roll intermittently, and therefore the rotational inertia of a heavy supply roll will pose serious problems. A more important deficiency is that the frame that carries the control rollers moves through the same distances and at the same speeds in its forward and its rearward strokes, and therefore the reduced radius portion of the delineating cylinder must extend around at least half of its circumference. This is to say that the delineating cylinder is effectively idle during at least half of each cycle, and output is correspondingly low. Since the frame that carries the control rollers is necessarily rather massive, its forward and rearward strokes must be made at relatively low speed to avoid inertia problems, further contributing to a low rate of production. The manner in which the feed rollers are driven for intermittent rotation also appears to be unsuitable for high speed operation.

The delineating cylinder of the Pinckert et al patent has a radial cutout which extends around only a small fraction of its circumference. During the short idle phase in which that cutout is juxtaposed to the opposing cylinder, the web is drawn rearward by a pair of feed rollers located a small distance upstream from the delineating cylinder. The feed rollers constantly rotate in the direction opposite to that of delineating cylinder rotation and in synchronism with that cylinder, but one of the feed rollers has a reduced radius around a major portion of its circumference, so that it cooperates with the other to grip the web and draw it rearward only during the idle phase of the delineating cylinder cycle. A dancer arrangement upstream from the feed rollers takes up and pays off web as necessary to maintain a steady rate of withdrawal of web from the supply roll.

With this Pinckert et al arrangement the web is, in theory, either being drawn forwardly by the operative peripheral portion of the delineating cylinder or drawn rearwardly by the operative peripheral portion of the one feed roller. However, the web cannot reverse its direction of lengthwise movement instantaneously, and the inevitable decelerations and accelerations must be accommodated by slippages which are indeterminate and variable, so that repeat interval length cannot be accurately maintained. Another and very important deficiency of this prior apparatus is that it has no provision for adjustably varying the decremental distance through which the web is moved rearwardly by the feed rollers, and therefore it does not provide for adjustable variation of repeat interval length.

In the apparatus disclosed by Bishop, the web is moved forward during the advancing phase by its engagement with the delineating cylinder. Accelerations, decelerations and rearward movements of the web during the idle phase are effected by means of a pair of feed rollers located just upstream from the nip that comprises the delineating cylinder, one rotatably driven and the other freely rotatable. During the advancing phase the freely-rotatable feed roller is spaced from the driven one; during the remainder of the cycle the feed roller nip is closed and a pinion coaxially fixed on the shaft of the driven feed roller is rotated by means of an arcuate rack which swings about a fixed axis spaced from the feed roller shafts. The arcuate rack is actuated for swinging back and forth motion, to impart forward and reverse rotations to the driven feed roller, by means of a pair of cams mounted on one end of the delineating cylinder and circumferentially adjustable relative to it, engaged by a cam follower on the rack. The arrangement is such that the delineating cylinder can produce an impression through only a little over half of each cycle, and therefore the rate of production tends to be slow. Accurate circumferential adjustment of the cams on the delineating cylinder, for adjustment of the decremental distance, seems to be difficult, at least in the form of the apparatus that the patent discloses. A further disadvantage for many applications is that during the advancing phase the web is driven only by the delineating cylinder, and therefore the apparatus is suitable only for rotary die cutting operations, for which it is specifically intended. In printing or offset work there would be a possibility of slippage of the delineating cylinder relative to the web.

In view of the deficiencies of the mechanisms disclosed in these prior patents, it is understandable that none of them is known to have had any significant commercialization. Instead, variation in repeat interval length has heretofore been provided for by means of interchangeable parts. A delineating cylinder had to be provided for each of a number of stepwise differing repeat interval lengths, each delineating cylinder having a circumference matched to the repeat interval for which it was intended, and for each such cylinder there had to be a special set of gears by which rotation of the delineating cylinder was synchronized with rotation of the several other cylinders and rollers on the machine.

With interchangeable delineating cylinders and their respective gear sets, a large capital investment was needed to equip a machine for a full range of repeat interval lengths, and some of that investment was always idle. Interchange of parts to convert from one repeat interval length to another was time consuming, and the cost of the skilled labor needed for such interchange was compounded by the loss of production while the interchange was being accomplished. A further important disadvantage was that only stepwise differing repeat interval lengths were available. Where the repeat interval length specified for a particular job fell between those respectively provided for by two sets of interchangeable parts, the job had to be run with the larger repeat interval, leaving the web with blanks between successive impressions along its length. In subsequent cutting of the web to the specified repeat interval lengths, these blank portions had to be discarded, increasing the cost of the job by the cost of the scrapped web material. Such web wastage tended to be especially high with apparatus that made no provision for varying the repeat interval length, as pointed out in the above-discussed Bishop patent, which also mentions that in the production of carton blanks and the like such wastage was often avoided by cutting the web into discrete lengths which were individually fed through the appartus, "thus introducing an additional machine and an extra handling step."

SUMMARY OF THE INVENTION

The general object of the present invention is to provide apparatus whereby uniform impressions can be made at regular repeat intervals along a web of indeterminate length, which apparatus does not have any of the disadvantages inherent in the above-discussed prior mechanisms but nevertheless provides for stepless adjusting variation of repeat interval length through a substantially wide range.

It is also an object of this invention to provide apparatus of the character described wherein a change in repeat interval length can be effected with a few simple adjustments that can be quickly and easily made, so that both the labor and the down time required for such a change are minimized.

Another and more specific object of the invention is to provide apparatus of the character described wherein the nip comprising the delineating cylinder is not relied upon to impart forward movement to the web so that there can be no slippage between the web and the delineating cylinder, and wherein the web is under positive control all through the rotational cycle of the delineating cylinder, with respect to accelerations and decelerations as well as with respect to steady-state forward and rearward motion.

It is also a specific object of the invention to provide apparatus of the character described wherein web is drawn off of a supply roll at a constant rate, to avoid problems incident to accelerations and decelerations of the rotational speed of a massive supply roll, and wherein the web is fed to a delivery zone at the same rate, to be wound onto a takeup roll or otherwise handled without problems due to fluctuations in the rate of its forward movement at the delivery zone.

Another specific object of the invention is to provide apparatus of the character described wherein the idle phase of the cycle of the delineating cylinder (i.e., the phase in each revolution of that cylinder during which it is out of contact with the web) need be no more than about one-third of that cycle, so that the productive phase is about twice as long as the idle phase to afford a high rate of output.

It is a further object of this invention to provide a web machine such as a press or a rotary die cutter that affords a high rate of production for each of a succession of jobs for which different repeat intervals are specified, the high production rate being achieved both because the machine operates at a good rate when in production and because down time between jobs is reduced by the speed and ease with which the repeat interval can be changed.

Another object of the invention, achieved in a preferred embodiment of it, is to provide apparatus of the above described character wherein the cyclically operating means that imparts alternate forward and rearward movement to web at the delineating cylinder has low inertia, comprising control rollers that are moved in circular orbits of adjustably variable radius.

In general, these and other objects of the invention that will appear as the description proceeds are achieved in apparatus comprising means for guiding a web of indeterminate length, drawn from a supply roll, lengthwise forward along a defined path through an impression zone that has front and rear ends which are spaced apart along said path and to a delivery zone, and a delineating cylinder cooperating with an opposing cylinder to define a nip in said impression zone through which the web passes and at which uniform impressions are produced on the web at uniform repeat intervals along it. The delineating cylinder may be a printing cylinder that carries a plate from which an impression is directly produced on the web, or a blanket cylinder such as is used in offset printing to which ink is transferred from an offset plate and which in turn transfers it to the web, or a die cylinder for cutting or scoring, or any similar cylinder that directly engages the web and produces an impression upon it. The delineating cylinder has a larger-radius peripheral portion and a smaller-radius peripheral portion that is defined by a cutout extending around a part of its circumference, to be out of contact with the web during an idle phase of each cycle of its rotation in which said cutout is juxtaposed to the opposing cylinder and to be capable of producing an impression on the web during an advancing phase which constitutes the remainder of said cycle. The apparatus further comprises drive means for rotating the delineating cylinder at a predetermined peripheral speed of its larger-radius portion.

The apparatus of this invention is characterized by a front pair and a rear pair of feed rollers, each of which pairs defines a nip through which the web passes to be fed forward by the pair, and one feed roller of each said pair is rotatably driven from said drive means at a substantially steady rate such that the length of web fed forward by the pair during each said cycle is equal to the length of a repeat interval. The rear pair is located along said path between the supply roll and the rear end of the impression zone, and the front pair is located along said path between the front end of the impression zone and the delivery zone.

The apparatus is further characterized by front and rear cyclically operating means, each comprising a control roller about which the web is looped, a carrier by which the control roller is carried for cyclical bodily movement transverse to its length whereby the loop of web around the control roller is alternately increased and permitted to decrease, and transmission means drivingly connecting the carrier with said drive means and whereby the carrier is actuated to carry the control roller through a cycle of its bodily movement during each said cycle of the delineating cylinder. The front cyclically operating means is located along said path between the front end of the impression zone and the front pair of feed rollers, for constraining web in the impression zone to move forward at a speed equal to said peripheral speed all during each advancing phase and allowing the web in that zone to move rearward during each idle phase. The rear cyclically operating means is located along said path between the rear pair of feed rollers and the rear end of the impression zone, for allowing web in that zone to move forward all during each advancing phase and constraining web in that zone to move rearward through a predetermined distance during each idle phase.

In a preferred form of the apparatus each cyclically operating means has a fixed axis about which its carrier is rotatable and is further characterized by control roller supporting means mounting its control roller on its carrier eccentrically to its fixed axis to be moved bodily in an orbit about that axis by rotation of the carrier, and means for adjustingly shifting the control roller supporting means radially relative to the carrier, towards and from said fixed axis, to adjustably vary the radius of said orbit and thereby adjustably vary the distance through which web in the impression zone is moved rearward during each idle phase. A variable ratio driving transmission is connected between said drive means and said one feed roller of each pair of feed rollers, for adjustably varying the length of web fed forward by the feed rollers during each cycle of rotation of the delineating cylinder.

In this preferred form of the apparatus the carrier of each cyclically operating means is freely rotatable about its fixed axis and each said transmission means further comprises a driver, a fixed cam means and a drive link. The driver is axially adjacent to the carrier, is confined to rotation coaxially with it and is connected with the drive means to be rotated thereby in unison with rotation of the delineating cylinder. The fixed cam means is axially adjacent to the driver and defines a cam track that is contained in a plane normal to said fixed axis and extends around the same. The drive link has a pivotal connection with the driver to be confined to swinging relative to the driver about a pivot axis which is spaced from and substantially parallel to said fixed axis. A first arm extends outwardly from said pivotal connection and has at its outer end a cam follower engaged with said cam track to be swung about said pivot axis during rotation of the driver by differences in the distance between said fixed axis and successive points along the cam track. A second arm extending outwardly from the pivotal connection is rigid with the first arm to be swingable with it and has at its outer end a connection with the carrier whereby the latter is constrained to rotate through one revolution for each revolution of the driver but is rotationally accelerated and decelerated relative to the driver by swinging of said arms.

BRIEF DESCRIPTION OF DRAWINGS

In the accompanying drawings, which illustrate what is now regarded as a preferred embodiment of the invention:

FIG. 1 is a simplified and somewhat schematic view in side elevation of apparatus embodying the principles of this invention, illustrated as a machine for a four-color process;

FIG. 2 is a plan view of the machine shown in FIG. 1;

FIG. 3 is a view of the cyclically operated means adjacent to one end of the machine, partly in elevation as seen looking along the path of web travel, but with portions broken away and shown in longitudinal section, and with each control link shown shifted around its carrier element by 90.degree. from its actual position;

FIG. 4 is a detail view taken substantially on the plane of the line 4--4 in FIG. 3, but showing the control link in its true position relative to the carrier element;

FIG. 5 is a fragmentary sectional view taken on the plane of the line 5--5 in FIG. 4, showing the control link its its connections to the driver, cam plate and carrier element;

FIG. 6 is a fragmentary view generally like the left-hand portion of FIG. 3 but on an enlarged scale and showing details of the mechanism for adjusting the radius of the orbit of the control roller; and

FIG. 7 is a view in longitudinal section of the variable ratio transmission through which the feed rollers are driven.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT OF THE INVENTION

General Arrangement and Operation

As pointed out hereinabove, the present invention is applicable to practically all operations in which a web of indeterminate length, of paper, paperboard, film, or the like, is moved lengthwise forwardly through a zone in which it is contacted by a rotating delineating cylinder 8 that makes an impression upon the web at uniform-length repeat intervals along it. Merely for purposes of example, the invention is here illustrated as embodied in apparatus that has four delineating cylinders 8 in its impression zone and can perform a four-color process, which can be either an offset process or a process for direct printing from plates on the delineating cylinders.

Thus, the illustrated apparatus comprises a horizontally elongated bed frame 5 upon which are mounted four towers 6A, 6B, 6C, and 6D, one for each of the colors in the process, all essentially identical. At least three of the four towers 6A-6D are adjustable as to their positions along the frame 5, and it will be understood that they are so positioned for any given job that the center-to-center distance between the adjacent towers is equal either to the repeat interval length specified for that job or to a whole-number multiple of that length.