US 3899946 A
A device for the print-referenced cutting of a printed web in which the effective circumference of a web feeding drum is slightly different from the print spacing, but can be increased or decreased, respectively by the selectively controlled approach motion of a counter roller against a depressible circumference portion of the drum, thereby advancing a longer or shorter web section. The approach motion is normally blocked by a solenoid controlled latch pin, the solenoid responding to a photoelectric cell.
Claims available in
Description (OCR text may contain errors)
[ 1 Aug. 19, 1975  References Cited UNITED STATES PATENTS DEVICE FOR THE PRINT-REFERENCED CUTTING OF A PRINTED WEB  Inventor: Otto Niepmann,Gevelsberg,
Germany Primary Examiner-Frank T. Yost Attorney, Agent, or Firm.1oseph A. Geiger & n n a y n .ma Nm 6 r FG e e .ma t mG 0 MC a m, 9 S A N 7  ABSTRACT A device for the print-referenced cutting of a printed  Filed: July 26, 1974 21 Appl. No.: 492,205
web in which the effective circumference of a web  Foreign Application Priority Data feeding drum is slightly different from the print spac- July 27, 1973 ing, but can be increased or decreased, respectively by the selectively controlled approach motion of a Germany............................ 2338109 counter roller against a depressible circumference [1.5. CI. portion of the drum thereby advancing a longer or 83/366; 83/367; 83/371; 83/436; 226/28; shorter web section. The approach motion is normally 226/19] blocked by a solenoid controlled latch pin, the sole- B65h 25/10 noid responding to a photoelectric cell. 83/75, 72, 322, 365, 366,
 Field of Search.........
14 Claims, 4 Drawing Figures PATENTEU Ans-1 9 I975 sum 1 [If 2 PATENTED AUB1 91975 sum 2 BF 2 Fig.4
Fig 3 DEVICE FOR THE PRINT-REFERENCED CUTTING OF A PRINTED WEB BACKGROUND OF THE INVENTION l. Field of the Invention The present invention relates to devices for cutting a printed web of paper or plastic material into discrete lengths, and in particular to devices for the printreferenced cutting of printed blanks for soft cigarette packages, using a feed roller cooperating with a counter roller.
2. Description of the Prior Art Devices for unwinding a continuous web from a supply roll and for cutting it into a series of blanks are known from the prior art. They feature a rotating feed drum with a cutting knife arranged on its periphery, the feed drum cooperating with a counter roller for both the cutting operation and the web advancing action.
Prior art devices of this kind, however, have the disadvantage of producing an invariable distance of web advance during each cutting cycle, thereby allowing registration errors that may occur between the printed patterns on the continuous web and the placement of the cut to accumulate.
SUMMARY OF THE INVENTION It is an objective of the present invention to suggest an improved device for the cutting of continuous printed webs where the placement of the cut is continuously referenced against the print on the web and the exact distance of web advance is adjusted accordingly, in order to compensate for any irregularities in the longitudinal spacing of the print patterns on the web and- /or for slippage that may occur on the circumference of the web-advancing feed drum.
The present invention proposes to attain the above objective by suggesting a novel device in which the circumference of the feed drum is slightly shorter or longer than the desired length of a cut printed blank, and where means are provided on the circumference of the feed drum which are depressible under the pressure of a counter roller so as to temporarily increase or decrease the effective drum circumference in response to a measurement of the position of the printed pattern in relation to the angular position of the cutting knife on the feed drum, as provided by a suitable monitoring unit.
Thus, the slightly undersized or over sized circumference of the feed drum in relation to the distance between successive printed patterns on the web will normally cause the printed blanks to be cut a small amount too short or too long, followed by a cumulative rearward shift or forward shift of the registration of the pattern in relation to the cutting knife, ifit were not for the arrangement of a controllable momentary change in the effective feed drum circumference, by means of which the length of the cut printed blank can be increased or decreased, in response to the actual position of the printed patterns on the continuous web, regardless of cumulative errors in the distance between successive printed patterns which may have been caused in the printing operation or otherwise. This selective change in the effective circumference of the feed drum is obtained, according to the present invention, by providing on the feed drum a circumference portion which is depressible radially, whereby the effective length of the web-engaging drum circumference is changed as a function of the radial depression. The distance over which the web is advanced during one revolution of the feed drum is accordingly increased or decreased by a given amount. The depression of the preferably resilient circumferential portion of the feed drum is obtained by means of an adjustably positioned counter roller which, for this purpose, is subjected to a short, precisely timed approach motion, during which it is pressed more strongly against the feed drum circumference. The counter roller approach motion is controlled by a print registration monitoring unit which operates in synchronism with the rotation of the cutting knife on the feed drum and which signals any lag in the print registration on the endless printed web, as the latter is unwound from a supply roll. In a preferred embodiment of the invention, this print registration monitoring unit includes a photoelectric cell which responds to the passage of certain reference marks on the printed web in front of the cell.
The novel device of the invention has the advantage of great simplicity, in that it utilizes the feed drum and the counter roller which are normally used for the advancing of the printed web and for cutting it into blanks, to perform the additional function of continuously compensating for variations in print registration. Thus, there are no additional elements required over which the printed web has to run, and which would complicate the web guidance, possibly reducing the efficiency of the device, while increasing its tendency to operational breakdown. The suggested novel device, therefore, uses the previously necessary feed drum and counter roller combination, adding only a depressible circumference portion to the drum, and arranging the counter roller on a bearing support which permits a controlled approach motion of the counter roller against the feed drum.
In order to obtain this additional approach motion of the counter roller against the feed drum, the invention further suggests, in a preferred embodiment, that the counter roller be journalled on a pivotable tumbling lever which is retainable in its normal position by means of a solenoid controlled latch pin and which, when the solenoid is energized, is pivoted under the influence of a tumbler spring, thereby approaching the counter roller against the feed drum through the action of an eccentric. According to a further feature of the preferred embodiment of the invention, the opposite end of the tumbler lever carries a cam follower, cooperating with a disc cam rotating in synchronism with the feed drum. This disc cam has an appropriately recessed circumferential portion which permits the pivoting motion of the tumbler lever during the angular motion range in which the counter roller faces the depressible circumference portion of the feed drum, while the remaining circumference of the cam disc holds the cam follower and the tumbler lever to their normal position in which the latch pin can re-engage the lever. The result is an accurately timed approach motion of the counter roller against the feed drum. The distance of the approach motion is adjustable through an adjustment of the orientation of the eccentric carrying the counter roller in relation to the tumbler lever. The frequency with which this corrective approach motion is executed is determined by the reading of the photoelectric cell.
The actual design of the feed drum with its compressible circumference portion may vary, depending upon the specific requirements of application. Thus, the depressible surface portion may be in the form of a resilient peripheral pressure cushion constituting a certain circumference portion of the feed drum, the counter roller deforming the cushion locally in conformance with its curvature, as suggested in the preferred embodiment of the invention. Alternatively, the depressible circumference portion may be provided in the form of a spring-biased radially movable pressure piston, or in the form of a similarly spring-biased, hinged pressure segment, occupying, for example, one-half of the feed drum circumference. In this case, however, the normally oversize drum circumference is selectively decreased.
In order to further enhance the accuracy of web advance, the preferred embodiment of the invention further suggests that in addition to the feed drum and counter roller combination carrying the cutting knife, there be arranged ahead of them a second feed drum and counter roller combination, the feed drum having again a depressible circumference portion and the counter roller being adapted for a similar selective approach motion, controlled by a print registration monitoring unit. This duplication of the variable circumference web advancing feature produces a more sensitive adjustment of the web advance, with the additional advantage that the forces necessary for the unwinding and movement of the printed web need not be produced by the feed drum carrying the Cutting knife. Especially the irregularly occurring deceleration forces are thereby kept away from the knife-carrying feed drum. A spring-biased idler arranged between the two feed drums assures an even web tension at the second feed drum.
The preferred embodiment of the invention, as mentioned, further provides for a convenient adjustment of the distance of the approach motion of the counter rollers from the normal position of their tumbler levers, through a simple angular adjustment of the eccentric which carries the bearings of the counter rollers.
BRIEF DESCRIPTION OF THE DRAWINGS Further special features and advantages of the invention will become apparent from the description following below, when taken together with the accompanying drawings which illustrate, by way of examples, several embodiments of the invention, represented in the various figures as follows:
FIG. 1 shows in a schematic representation a mechanism configuration embodying the invention and corresponding to a side view thereof;
FIG. 2 shows a partial transverse section through the device of FIG. 1, the section being taken along line IIII thereof;
FIG. 3 shows a second version of a feed drum, as part of a modified embodiment of the invention; and
FIG. 4 shows a third version of the feed drum, as part of another modified embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS The device of the invention, illustrated in FIG. 1 in a schematical manner only, is designed for the cutting of a continuous printed web 1 which is unwound from a supply roll 2. The unwinding and advance of web 1 is obtained by means of two pairs of cooperating rollers, each pair consisting of a feed drum 3 or 3a and of a counter roller 4 or 4a, respectively. The web portion running between the two roller pairs is engaged by an idler 5. The latter is mounted on a pivotable idler lever 6 and biased by a tension spring 7 which maintains a constant web tension between the two roller pairs, regardless of variations in web length.
The feed drum 3 of the second roller pair is equipped with a cutting knife 8 arranged on its periphery, the knife 8 cooperating with the counter roller 4 so as to cut a single blank from the printed web 1 during each drum revolution. Each cut blank carries the same printed pattern. This roller pair thus not only advances the web 1, but also cuts it into a series of printed blanks. The latter may be labels, package blanks, or the like, especially blanks for soft packages of cigarettes.
In the embodiment shown in FIG. 1, each of the two feed drums 3 and 3a have on one portion of the periphery a resiliently compressible cushion 9 which represents a depressible circumference portion of the feed drum. The counter roller 4 or 4a, respectively, which cooperates with this depressible circumference portion and with the remaining periphery of the feed drum to advance the printed web 1, is supported on a tumbler lever 10 or 10a, respectively, the lever being pivotable between a normal position in which the roller pair advances a web length equal to 3.14 times the diameter of the feed drum, and an approach position in which the counter roller 4 or 4a, presses into the peripheral cushion 9 or drum 3 or 30, respectively. The two tumbler levers l0 and 10a are biased toward this approach position by means of tension springs 11 and 11a, respectively, the levers being selectively held in their normal position by means of a trigger mechanism. This trigger mechanism consists of a latch pin 12 controlled by a solenoid 13, as shown in FIG. 2. There, it can be seen that, when the solenoid 13 is energized, it retracts the latch pin 12 from the tumbler lever 10, allowing the latter to make its approach motion.
The timing, duration, and distance of the approach motion of the counter rollers 4 and 4a against their cooperating feed drums 3 and 3a, as determined by the pivoting motion of the tumbler levers l0 and 10a, are controlled by means of a cam follower 14 arranged on the tumbler lever and engaging a disc cam 15 rotating in synchronism with the feed drums 3 and 3a. The disc cam 15 has on its periphery a recessed cam portion or depression 16 into which the cam follower 14 can descend for the approach motion of the tumbler lever. The depression 16 of the disc cam 15 thus determines both the timing and the distance of the approach motion of the counter roller 4 against the peripheral cushion 9, if an approach motion has been triggered by the solenoid 13.
The two feed drums 3 and 3a have a diameter which gives them a circumference which is just slightly smaller than the circumference which would be needed to advance the printed web 1 from one printed pattern to the next. Thus, when the web 1 is so positioned that the cutting knife 8 cuts a printed blank at the proper registration, the next cut will produce a slightly short cut blank, unless the effective circumference of the feed drum is corrected to produce a slightly long cut blank. Such a circumference correction is obtained through the approach motion of the counter rollers 4 and 4a against the circumferential cushions 9 of the feed drums 3 and 3a, respectively, whereby the effective circumference on the feed drums is temporarily increased to a length which is just slightly greater than the distance between two printed patterns on web 1, thereby reducing or eliminating any lag of the printed web 1 in relation to the cutting knife 8. The increase in the effective circumference of the feed drum is obtained through the depression of its peripheral cushion 9 under the approach motion of the counter roller, which thereby impresses its smaller curvature into the cushion 9 and produces a sinuous curvature of momentarily increased length, so that an additional small increment of web length is advanced between the roller pair.
As mentioned, the approach motion of the counter rollers 4 and 4a is not performed during each revolution of the feed drums 3 and 30, but is triggered selectively, whenever the printed web 1 lags behind the cutting knife 8. That condition is monitored by means of a print registration monitoring unit, consisting essentially of a photoelectric cell 17 which, at a given angular position of the feed drum 3, verifies the position of a reference mark on the printed web 1. If that mark is in the proper place, or slightly ahead, the photoelectric cell will not respond. Inthis case, no approach motion between the roller pair will occur, because the latch pin 12 retains the tumbler lever in its normal position. But, if the photoelectric cell 17 finds the reference mark on the printed web 1 lagging behind, it will trigger the solenoid 13 to retract the latch pin 12, thereby releasing the tubler lever 10 to be pivoted under the influence of the tumbling spring 1], when the cam follower 14 reaches the depression 16 of the disc cam 15. This circumference correction on the feed drums is repeated, if necessary, for a number of consecutive *long" cuts, so that the position of the printed pattern on the continuously running web 1 advances to its desired position. at'which point the photoelectric cell 17 no longer triggers the corrective approach motion. Since the tumbler levers 10 and 10a are maintained in their normal position during a major portion of each revolution, the latch pin 12, when released by the solenoid 13, will reengage the tumbler lever 10, as soon as the corrective advance is no longer required. The latch pin 12 then remains engaged, until the photoelectric cell 17 signals a new lag of the web 1. Thus, the device of the invention will alternatingly produce a series of slightly short cut blanks, followed by a series of slightly long cut blanks. with the printed pattern accurately registered on the blanks.
The disc earns and their cooperating cam followers 13 determine, during each revolution, both the exact timing and the displacement of the approach motion of the counter rollers on the tumbler levers 10 and 10a, respectively. Obviously, this approach motion must coincide with the angular position of the peripheral cushion 9 against the counter rollers. Thus, both the timing and the distance of the approach motion can be adjusted by replacing the disc cam 15 with a cam having a different depression 16. On the other hand, the position of the counter rollers 4 and 4a is also adjustable in relation to their feed drums 3 and 30. by adjusting the orientation of the eccentrics on which they are journalled in relation to the tumbler levers l0 and 100, respectively.
The the arrangement of FIG. 1 illustrates a second photoelectric cell 17a controlling the first roller pair 3a, 4a. Alternatively, the first roller pair may be replaced by a variable-speed advancing device whose speed is adjusted in response to the web tension ahead of the cutter feed drum 3, as reflected by the position of the spring-biased idler 5.
The depressible peripheral cushion 9 of the feed drums 3 and 3a is preferably of a resilient compressible material, such as rubber, occupying a portion of the drum circumference. However, alternative depressible circumference portions may be provided on the feed drums, as shown in FIGS. 3 and 4, for example. Here, a solid, radially biased member of metal or plastic material forms a portion of the drum circumference. In FIG. 3, the depressible member is a pressure piston 18 which is normally held in alignment with the periphery of drum 3 by means of a compression spring 19, against which it is depressible under the approach motion of the counter roller (not shown). In the embodiment of FIG. 4, the depressible member is a pressure segment 20 which is hinged to the drum 3 on one of its extremities and biased radially outwardly by a spring 21 on its opposite extremity. Again, an approach motion of the counter roller depresses the segment 20 radially inwardly, thereby temporarily decreasing the effective circumference of the feed drum. Obviously, in this case, as in the case of the pressure piston of FIG. 3, the print registration monitoring unit responds to a lead deviation of a reference mark, rather than to a lag deviation, the entire operation being otherwise identical.
It should be understood, of course, that the foregoing disclosure describes only preferred embodiments of the invention and that it is intended to cover all changes and modifications of these examples of the invention which fall within the scope of the appended claims.
1. In an apparatus for cutting a continuous web, having regularly spaced printed patterns or other readable markings thereon, into a series of blanks whose cuts are positioned substantially at the same distance with reference to the printed pattern, regardless of cumulative deviations in the web advance and/or in the pattern spacing on the web, a device for varying the web advance per cutting cycle in reference to the position of the printed pattern on the web, the device comprising in combination:
a pair of web advancing rollers, engaging the printed web from opposite sides, one roller being a feed drum, rotating at constant speed, the other roller serving as a counter roller;
a radially oriented cutting knife on the periphery of the feed drum, cutting the web once during each drum revolution so as to obtain, with each cut, a printed blank of a length corresponding to the circumference of the feed drum;
a deformable circumference portion on the feed drum defined by a radially depressible member of the feed drum;
a circumference on the feed drum with, in the absence of deformation of said circumference portion, advances a blank length which is slightly less than the distance at which the printed patterns are spaced on the web;
means for forcibly approaching the counter roller against the feed drum during that angle of drum revolution in which the roller faces the deformable circumference portion of the drum, thereby depressing said member of the drum and temporarily increasing its effective circumference, so as to advance a blank length which is longer than that which would be advanced without such depression; and
means for selectively controlling the approaching means to execute, or not to execute, said approach motion during any given drum revolution, in response to the position of the printed pattern on the web in relation to the angular position of the cutting knife on the drum.
2. A device as defined in claim 1, wherein:
the counter roller approaching means includes a pivotable tumbler lever carrying the counter roller at a small distance from the pivot center of the lever, and a tumbler spring engaging said lever, the latter being pivotable between a normal position in which the counter roller cooperates with the feed drum without depressing its depressible member, and an approach position in which said depression takes place; said spring biasing the tumbler lever toward its approach position; and
the approach controlling means is a means for selectively blocking the tumbler lever from executing the counter roller approach motion.
3. A device as defined in claim 2, wherein the counter roller approaching means further includes means for holding the tumbler lever in its normal position, against the tumbler spring, during that angle of drum revolution in which the counter roller does not face the deformable circumference portion of the feed drum.
4. A device as defined in claim 2, wherein the counter roller approaching means further includes:
a cam follower carried by the tumbler lever;
a control cam arranged for synchronous rotation with the feed drum and engaging the cam follower in a one-way engagement in opposition to the tumbler spring;
a circular high section on the control cam holding the tumbler lever in its normal position, against the tumbler spring, during that angle of drum revolution in which the counter roller does not face the deformable circumference portion of the drum; and
a low cam section which, when the blocking means is inoperative, allows the tumbler lever to execute the approach motion to the approach position, and back, the motion force being provided by the tumbler spring and the displacement being determined by the cam surface.
5. A device as defined in claim 4, wherein the tumbler lever blocking means includes:
a retractable blocking element which is normally positioned in the way of the tumbler lever so as to prevent it from executing an approach motion;
a spring biasing the blocking element against retraction;
a solenoid which, when energized, retracts the blocking member; and
means for selectively energizing the solenoid in response to the position of the printed pattern on the web in relation to the angular position of the cutting knife on the feed drum.
6. A device as defined in claim 5, wherein the solenoid energizing means includes a photoelectric cell which is arranged to read a reference mark of each printed pattern on the moving web, at a given angular position of the cutting knife on the feed drum, and in response to its reading, to initiate energization of the solenoid, if the position of said reference mark is behind its normal position.
7. A device as defined in claim 2, wherein in relation to a given pivoting angle of the tumbler lever between said two positions, the two corresponding positions of the counter roller are adjustable both in terms of motion distance and of the distance of its end positions from the feed drum, by an. adjustable eccentric arranged on the tumbler lever on which the counter roller is journalled. 8. A device as defined in claim 1, wherein the radially depressible member of the feed drum which defines the deformable circumference portion is a resiliently compressible pressure cushion which, in its non-compressed state, forms a part of a regular cylindrical outline of the feed drum.
9. A device as defined in claim 1, wherein the radially depressible member of the feed drum which defines the deformable circumference portion is a radially guided pressure piston and includes a compression spring biasing the piston outwardly against'an abutment, the piston forming in its abutted position a part of a regular cylindrical outline of the feed drum.
10. A device as defined in claim 1, wherein the radially depressible member of the feed drum which defines the deformable circumference portion is a pressure segment which is pivotably attached to the feed drum and includes a spring biasing the segment outwardly against an abutment, the segment forming in its abutted position a part of a regular cylindrical outline of the feed drum.
1 l. A device as defined in claim 1, further comprising means for feeding the printed web to the pair of web advancing rollers at a variable speed, adjusted in response to the web tension exerted by said roller pair.
12. A device as defined in claim 1, further comprising means for feeding the printed web to the pair of web advancing rollers at a variable speed, adjusted in response to the position of the printed pattern on the web.
13. A device as defined in claim 12, wherein:
the web feeding means includes a second, similar pair of web advancing rollers, the feed drum and counter roller being substantially the same as those of the first-mentioned roller pair, but for the absence of a cutting knife on the second feed drum; and
the second roller pair is similarly combined with counter roller approaching means and selective approach controlling means, responding to the position of the printed pattern on the web in relation to theangular position of the second feed drum.
14. A device as defined in claim 13, wherein the web feeding means further includes an idler on a spring-loaded pivot arm for establishing an even web tension between the web advancing roller pair and the web cutting roller pair.