US 3126431 A
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Description (OCR text may contain errors)
March 24, 1964 J. R. HARDER ETA].
METHOD OF REGISTRATION OF INDICIA Fi led Aug. 23, 1960 2 Sheets-Sheet 1 INVENTORS John R. Harder Reid A. Muhoffy BY William E. Young awiallorr/ nesefl/i ATTORNEYS March 24, 1964 J. R. HARDER ETAL METHOD OF REGISTRATION OF INDICIA 2 Sheets-Sheet 2 Filed Aug. 23, 1960 SZIZE INVENTORS John R. Harder Reid A Mahoffy William E Young Glut/ g Marv/S, 13%4 ATTORNEYS United States Patent 3,126,431 METHOD OF REGISTRATION OF INDICIA John R. Harder, 101 Cedar Grove Parkway, Cedar Grove,
N..l.; Reid A. Mahafiy, 105 Clinton Ave, Montclair,
N.J.; and William E. Young, 46 Cooper Ave., Roseland, NJ.
Filed Aug. 23, 1960, Ser. No. 51,342 5 Claims. (Cl. 264-40) This invention relates to registration of indicia. More in particular, this invention relates to a method and apparatus for applying repetitive indicia, e.g. on a continuous web of material, to a correspending series of receiving elements or devices. In a preferred embodiment of the invention described herein, means are provided for producing containers from flexible plastic material bearing indicia such as an identification of the packaged product.
When containers are produced from rolls of flexible indicia-bearing packaging material it often is desired that the indicia appear in the same predetermined position on each container. Such containers commonly are produced by machines having a number of substantially identical container forming devices (referred to herein as formers), generally mounted for movement in a chain or on a drum. The indicia on the packaging material fed to thsese formers are evenly spaced apart a distance nominally equal to the spacing of the formers. It will be appreciated, however, that the spacing of the indicia cannot be maintained at exactly the spacing of the formers, due to manufacturing tolerances, humidity effects, etc. Thus there is a problem in obtaining the desired registration between the indicia and the container formers. Periodic correction of the longitudinal relationship is essential because even minute differences between indicia and former spacing tend to accumulate, resulting in substantial displacement of the indicia from the desired position on the containers.
In many container-forming machines, the packaging material is supplied to the formers through draw-rollers driven in timed relationship to the advance of the formers. The indicia may be placed on the packaging material with a longitudinal spacing smaller than the spacing (center-to-center) of adjacent formers. An electrically-operated clutch, interposed between the machine drive and the draw-rollers, is actuated by an electric eye responsive to the indicia and timed to act in synchronism with the advance of the formers. When the draw-rollers have advanced the indicia to the desired position relative to the formers, the clutch disconnects the rollers from their drive and a brake is applied, halting feeding of packaging material to the formers for a predetermined period.
Although the packaging material and the formers advance together most of the time, it will be evident that relative motion exists between the material gripped between the draw-rollers and the formers Whenever the rollers are declutched from the machine drive and stopped. In order not to disturb the material already clamped to or being processed by the formers when the aforementioned relative motion occurs, it has been common practice to sever the material in the formers from the material still controlled by the draw-rollers.
Since it often is advantageous to form indicia-bearing containers in a continuous strip, various methods have been proposed to avoid the previously described severing operation. For example, as described in various publications such as U.S. Patent 2,546,059, it has been proposed to continue the above-mentioned relative movement without severing, and allow the material between the formers and the feed-rollers to stretch until proper 3,126,431 Patented Mar. 24, 1964 registration is obtained. However, it has been found that this method introduces certain problems.
As an example of such problems, it has been found that many preferred packaging materials, e.g. biaxiallyoriented polyethylene terephthalate and its combinations, require relatively high stresses to produce the amount of stretch needed to register indicia printed thereon. These high stresses make it difiicult, if not impossible, to hold the packaging material in the container formers without undesirable distortion, tearing, or other damage to the container, and particularly may cause wrinkling of the material which interferes with subsequent hermetic sealing of the package. Also, this proposed method does not lend itself to packaging machines wherein the formers are driven intermittently, since the sudden application of force to highly-stressed packaging material each time the formers are advanced can result in fracture of the packaging material between the feed rolls and the formers to which the material is secured. In one aspect of this invention, such diificulties with prior registration methods are overcome in an arrangement wherein the packaging material is controllably stretched independently of the container formers, advantageously to an extent providing a permanent set elongation of the material. Thereafter, the material is applied to the formers under a tension substantially less than that required to produce the permanent set.
Accordingly, it is an object of this invention to provide an improved method and means of registering indicia. Another object of this invention is to provide, in container-forming equipment, a method for registration of a continuous sheet of indicia on high strength extensible materials. Other objects, aspects and advantages of the invention will in part be pointed out in, and in part apparent from, the following description of a preferred embodiment of the invention. In considering the drawings herein, it should be noted that they show the present invention applied to a packaging machine of the type disclosed in copending application Serial No. 842,365, filed on September 25, 1959, by Reid A. Mahaify, and since issued as US. Patent 3,061,984. In the drawings:
FIGURE 1 is a fragmentary rear elevation of the packaging machine shown in FIGURES 1 through 4 of the above-mentioned copending application, with registration mechanism added;
FIGURE 2 is a fragmentary top plan view of the machine shown in FIGURE 1; and
FIGURE 3 is a simplified schematic diagram showing an energizing circuit interconnecting the differential unit and the controlling electric eye.
Referring now to the lower left corner of FIGURE 1, there is provided a rolled-up sheet 1 of extensible packaging material mounted on an unwind shaft 2. (NOTE- The reference numerals on the drawings herein are identical with those of the above-mentioned copending application, where the same parts are involved.) The sheet is drawn from its roll by the powered draw-roll units 59 and 3, and passes under idler roller 4 where it is secured to an endless chain of packaging trays 5 by a pair of clamps 6 which are mounted on each of the trays. The chain of trays is supported by sprockets (not shown) mounted on a shaft carrying gear 58. This gear is operated intermittently by a suitable drive, such as a Geneva mechanism, so as to successively place the trays in position for the various package forming operations.
Referring also to FIGURE 2, the prime mover (not shown powering the intermittent drive also continuously drives draw-roll unit 3 through the usual chain, a sprocket 40 and an electrically-operable clutch 60. The drive ratios in themachine are so selected that draw-roll unit 3 feeds sheet 1 continuously at a somewhat greater rate than the average outer surface speed of the intermittently moving trays 5. A dancer roll 61, mounted on spring-biased arms 63 pivoted on pins 62, maintains a moderate tension in sheet 1 between trays Sand draw-rolls 3 until over-feed from the draw-rolls causes dancer 61 to elevate to its highest position. At this point, a limit switch 64 is actuated to release clutch 60, through a conventional electric circuit (not shown), thereby halting further feeding of sheet 1 by draw-rolls 3. A brake 65 also is applied to the draw-rolls 3 simultaneously with release of clutch 60 to substantially eliminate any overfeed due to the momentum of the rolls. Further indexing of trays will cause sheet 1 to depress dancer roll 61, thereby releasing arms 63 from engagement with switch 64 so as to release brake 65 and re-engage clutch 60 to resume feeding of sheet 1.
The other draw-roll unit 59 is driven from draw-roll unit 3 through change-gears 67 and a differential unit 68 of conventional construction. This differential unit normally provides a 1:1 drive ratio between its input shaft 68a and its output shaft 68b, but is actuable by an electric signal to slow the draw-roll unit 59 momentarily. The drive ratio of change-gears 67 is so selected that draw-roll unit 59 feeds sheet 1 at a speed less than that of draw-roll unit 3, so as to stretch the portion of sheet 1 located therebetween. The tension placed on sheet 1 by the spring-biased dancer roll 61'is substantially smaller than that produced between the draw-roll units.
Operation of the differential unit 68 is controlled by an electric eye 71 responsive to indicia 66 which have been previously applied to the sheet 1 at a longitudinal spacing less than the center-to-center spacing of the trays 5. As shown schematically in FIGURE 3, the output circuit of the electric eye '71 is connected in series with a normally closed switch 69 operated by a cam 70 which is continuously driven by the machine prime mover at a speed to make one revolution for each indexing cycle of the trays 5. This cam is so arranged that its flat portion 72 opens switch 69 during the time that the indicia should be in front of electric eye 71 to provide proper registration thereof with the trays 5.
If the indicia 66 arrives in front of the electric eye 71 prior to the time that the cam-operated switch 69 has opened, the electric eye will complete an energizing circuit through this switch to a relay 73. This relay thereupon is actuated to energize the dilferential unit 68 which causes the draw-roll unit 59 to operate at a somewhat slower speed as long as the relay remains actuated. Relay 73 is provided with a conventional hold circuit (not shown) to maintain the relay actuated until the hold circuit is disabled by another switch 74 which subsequently is operated by the flat portion 72 of cam 70.
Even though the indicia 66 are in proper registry, relay 73 nevertheless is actuated during each cycle of cam 70 by a third switch 75 which is normally open, the relay being held in until the cam flat 72 reaches switch 74. The equipment is so arranged that the resulting standard correction (of constant magnitude) thereby introduced by differential unit 68 produces a permanent set in the sheet 1 stretched between the draw-rollers 3 and 59. If the indicia 66 are not within the registration tolerance, as determined by the circumferential length of cam flat 72, relay 73 will be energized by electric eye 71 prior to the operation of the third switch 75, and thus the correction introduced by differential 68 will be larger than the standard correction by an amount related to the extent of the registration error.
This arrangement of providing a standard correction once each cycle, and a trimming correction whenever needed, has been found to produce desirably precise control.
When the stretched sheet subsequently is applied to the trays 5, it retains the desired elongation even though it is stressed only by the moderate tension of dancer 61. It should, of course, be recognized that some packaging materials tend to creep back after a period of time, and therefore the term permanent set is used herein to mean a set which lasts without significant creep-back at least for the period of time required to complete the necessary packaging operations such as heat-sealing and/ or severing, as described in the above-mentioned copending application.
The spacing between the indicia 66 and the amount of correction introduced by differential unit 68 are so related, with respect to the spacing between trays 5, that the indicia normally will never appear in front of electric eye 71 any significant time after the cam-operated switch 69 has opened. When one of the indicia does appear after the switch has opened, only the standard correction will be introduced. During the next several cycles, the indicia may continue to appear in front of the eye while this switch is open. However, ultimately the indicia will appear in front of the eye 71 ahead of time, i.e. while the cam-operated switch 69 is still closed, because the standard correction is insufficient to produce registration. The trimming correction then will be introduced by a momentary further increase in the stretching of sheet 1, and this correction may be introduced for one or more cycles in sequence until the indicia again appears before eye 71 at the proper time, i.e. after the switch contacts have opened. Accordingly, cumulative errors in registration are prevented.
It will be apparent that the electric eye 71 may be so positioned vertically as to cause the indicia 66 to be longitudinally located in any desired position on each of the finished packages. Auxiliary heating means, or heating of the rollers in the draw-roll units, may be employed for heating the sheet 1 to enhance the stretching thereof. Application of a fluid plasticizer to the sheet may also aid in stretching some materials. The positioning of switches 69, 74 and 75 about the circumference of cam 70 may be adjusted to accommodate different kinds of packaging material or to suit particular applications.
Although a preferred embodiment of the invention has been set forth in detail, it is desired to emphasize that this is not intended to be exhaustive or necessarily limiting; on the contrary, the showing herein is for the purpose of illustrating the invention and thus to enable others skilled in the art to adapt the invention in such ways as meet the requirements of particular applicatrons, it being understood that various modifications may be made without departing from the scope of the invention as limited by the prior art.
1. The method of registering indicia on a web of material with elements to which said material is to be applied, comprising the steps of advancing said material towards said elements, stretching said material in the longitudinal direction with a predetermined tension, maintaining a desired registration of said indicia by altering said predetermined tension in the appropriate direction in response to changes in the positioning of said indica with respect to a position providing the desired registration with said elements, and applying said material to said elements under a tension less than said predetermined tension.
2. The method of claim 1, including the steps of sensing the positioning of said indicia, comparing the sensed positioning of said indicia with a desired positionng thereof provding registration with said elements, and controlling the extent of said stretching in accordance with deviations between the positioning of said indicia and the desired positioning and in a direction to shift said indicia towards the desired positioning.
3. The method of registering indicia on a web of flexible packaging material with moving container forming elements to which said material is to be applied, comprising the steps of stretching the material beyond the elastic limit thereof, adjusting the amount of stretching applied to said material in response to changes in the positioning of said indicia with respect to a desired positioning thereof providing registration with said elements, the stretching being adjusted in a direction to return said indicia to said desired positioning, relaxing said stretched material while maintaining its length greater than its original length, and applying said relaxed material to said elements.
4. The method of registering indicia on a web of flexible packaging material with a series of moving container forming elements to which the material is to be applied, comprising the steps of advancing the material towards said elements, stretching said material beyond its elastic limit while it is being advanced, adjusting the amount of stretching applied to said material in response to changes in the positioning of said indicia with respect to said elements and in a direction to maintain a desired registration of said indicia with respect to said elements, relaxing said stretched material substantially to its permanent set elongation, and applying said relaxed material to said elements.
5. The method of registering indicia on a flexible sheet of material with elements to which the sheet is to be applied, comprising the steps of stretching the material with a tension sufiicient to give the material a permanent set, altering the amount of stretching of said material in accordance with changes in the positioning of said indicia with respect to a desired positioning thereof providing registration with said elements and in a direction to maintain said desired positioning, holding said material approximately at its permanent set dimension with a tension less than said first-mentioned tension, and applying said material under said lesser tension to said elements.
References Cited in the file of this patent