US 3146431 A
Description (OCR text may contain errors)
Aug. 25, 1964 R. c. BETTS WEB END CONTROL Filed July 22, 1958 PACKAGING MACHINE WARNING DEVICE CONTROL Fig. 6
ROSS C BETTS 52 I Ejl ATTOR NEYS United States Patent 3,146,431 WEB END CONTROL Ross 6. Betts, Rocky River, Ohio, assignor to The Dow This invention relates to means and apparatus for the end control of webs of packaging films and the like in.
packaging machinery or similar web converting equipment. This invention is finding particular usefulness in handling narrow webs, such as tear tapes which are combined with Wider Webs of packaging film to provide a means for easily opening the wrapped package. The tear tape now customarily provided for opening the cellophane overwrap in a cigarette package is the most widely employed example of such narrow packaging webs.
Referring particularly to tear tapes for cigarette packages and the like, the problem of securing a suitable warning or control of the approaching end of the tape as it is fed from the spool or roll into the packaging machine has become increasingly troublesome as the speeds of automatic packaging machinery have increased. Such tear tapes, normally employed in widths ranging between onesixteenth to one-eighth inch, are generally supplied to the,
packager on carefully and tightly wound spools. Such tapes vary widely in thickness, depending upon the thickness of the film from which they are slit and depending upon whether such film is uncoated single-ply stock, single-ply stock coated on one or both sides, or laminated multi-ply stock. Thus, the length of tape per pound as supplied on a spool will vary greatly but, in any event,
the ratio of continuous spooled length of such tape with respect to its width will be extremely great. For example, a standard three-pound spool of 2 tape of the gauge currently most popular in the cigarette industry will supply a continuous length of tape approximately six miles long (5.85 miles, +5%).
The spooled tear tapes in question are fed into a ciga rette packaging machine by means of attachments furnished by the manufacturers of the packaging machinery. These attachments may differ in construction and location, depending upon the model and type of packaging machine, but characteristically include a guide roll for guiding the tape from the spool into the machine and a web control for stopping the machine in the event of a break, either in the tear tape or the wider web of packag ing film. These machines are customarily installed in banks or batteries of several machines tended by one or more attendants. With the slower, old machines, not only were there longer intervals between tear tape spool changes, but the rate of take-off of the tape from the spool was slow enough so that the attendants had ample time, among their other duties, to anticipate the run-out of a spool of tear tape and be on hand to splice a new spool when required. And, in the event a spool did run out before a new spool was spliced on, the break-control would stop the machine until an attendant spliced on a new spool. As the speeds of new packaging machinery increased, however, tear tape spool changes, for a given size spool, necessarily became more frequent, as did stoppages due to insufficiently anticipated run-outs. Any downtime of packaging machinery has always been highly undesirable and the occurrence of more stoppages due to spool run-out threatened to offset at least some of the increase in efficiency of the newer, higher-speed packaging machines.
A direct answer to the problem of increased frequency of spool changes in higher-speed machines seemed to be simply that of increasing spool size proportionately to the increase in packaging machine speed; this proved to be illusory, mechanically, operationally, and economically. Mechanically, the greater inertia of the larger spools added back-lash problems and the danger of breaking the tape while accelerating the heavier spools; operationally, the last few layers of tape on the spool core still ran out at a high speed and presented the danger of an unanticipated run-out; and, economically, the added number of spool sizes multiplied the inventory problems and, thus, the manufacturing and distributing costs, of the film converters who produce such tear tapes.
It is an object and advantage of this invention to offset the problems of increased web speeds and frequency of spool or like web supply changes in packaging and like web-converting machinery by providing a simple and effective means, including triggering means on the web itself, whereby the approaching end of the web will be suitably signaled to the machinery attendant and/ or automatic means will be actuated either to slow down web speed or to attach a new web supply to that being exhausted. To meet this object of this invention, the means responsive to the triggering means in the web must be (a) responsive to a signaling impulse of extremely short duration relative to the interval between impulses but (b) tolerant of a substantial variation in the duration of the signaling impulse (since the web must be adaptable to machines calling for a wide variation in web speeds). Further, the triggering means on the web must not discolor or disfigure the web for any substantial portion of its length (since any substantial length of discolored or disfigured web will produce a rejectable package). These requirements appear to eliminate, for practical purposes, any so-called electric eye means resp0nsive to a decrease in light reflected from a non-reflective target printed on the characteristically shiny packaging film. In high-speed machinery such a non-reflective target of sufficient length to actuate a photo-electric cell would be likely to mar the package in which the target portion of the web appeared. Electric eye means which function in response to interruption of a light beam transmitted through the web are impractical because many tear tapes or other packaging webs are themselves opaque.
In general, the objects, advantages, and requirements of this invention are met by providing adjacent the final end of the web an electrically conducting area which will momentarily close a circuit to produce an impulse which, in turn, actuates a suitable signal means or the like. It is, however, a requirement of this invention that such an electrical conducting area be unaffected by waxes, plasticizers, and the like on the preceding portion of the web and which would insulate electrical contact means from the conducting area.
Other objects, advantages, and requirements of this invention will be apparent from the following specification, claims, and drawings, in which:
FIGURE 1 is a plan view, broken away to shorten the longitudinal dimension of a web from which a tear tape embodying the invention is produced.
FIGURE 2 is a longitudinal cross-section of a tear tape embodying this invention, taken along the lines 22 of FIGURE 1.
FIGURE 3 is an elevation of a continuous length of tear tape as shown in FIGURE 2 suitably spooled for use in packaging machinery. For purposes of illustration, the width of the tear tape, with respect tothe length of the spool, is greatly exaggerated.
FIGURE 4 is a cross section taken along the lines 4-4 of FIGURE 3. For purposes of illustration, the thickness of the tear tape and conducting area are greatly exaggerated.
FIGURE 5 is a diagrammatic showing of the location of the web control with respect to the web supply and a packaging machine.
FIGURE 6 is a diagram of the circuit of the control shown in FIGURE 5.
As a specific embodiment, this invention will be disclosed. as employed in connection. with a single-ply packaging tear tape.
\ As indicated in FIGURE 1, a packaging tear tape 10 is conventionallywproduced bylongitudinally slitting a wider web 20 of tear tape material. The web 20 itselfis usually produced by slitting a still wider web. Thus, for example, if the tear tape 10 in FIGURE 1 is /8 inch wide, the web 20 is one inch wide and will, itself, have been produced by slitting a still wider web. To provide the substantially continuous spool lengths of tear tape 10, lengths of the web 20- are suitably spliced prior to feeding theweb 20- into the slitter in which the tapes 10 are slit.
As a given spool lengthof tape- 10 has been drawn through a conventional slitter and commenced to be wound on the. spool 30, on which it will be shipped to the packager, a swatch 21 of thin, flexible material having at least an outer conductive surface is. adhered across the web 20. The distancefrom the end of the tape 10 wound on thespool 30 to the swatch 21 is determined by maximum lineal speed at which the tape 10 is tobe fed into any packaging. machinery in which it will be used and the minimum period required to Warn the machinery attendant that the spool is running out. Thus, for example, if the maximum lineal speed at which the tape will be used is 100 feet per minute and-the minimum warning period is two minutes, the swatch 21 will be lo cated on the web 20 a distance of 200 feet away from the endof the tape being wound on the core of the spool 30;
If the same spooled tape should beused in a packaging machine using tear tape at the rate of only 50 feet per minute, manifestly a four-minute warning will be given.
As the web 20 with its adhered swatch 21 is slit intotapes 10, the tapes are provided with a conducting patch 11 wound on the spool Fill-at the desired distance fromthecore of the spool. As indicated in FIGURE 2, the thickness-of the patch llmay bein the same order of thickness as the film of the tape 10 or it maybe thinner. Suitable material for the patch 11 is a film of styrene, polyethylene terephthalate, or like film to which a vacuumdeposited aluminum vapor will firmly adhere, such .film being adhered to the tape 10 with its metalized surface outermost. Other suitable materials for the patch ll; are
aluminum and soft copper foils. The length. of the patch 11 is relatively immaterial, regardless of the expected speed of the tape 10 since, in any given packaging ma-- chine, the length of the commutator brushes simultaneously contacting the patch 11 may be selected to insure an impulse of sufficient duration to actuate any reasonably quickly responive sensing relay. Thus, if the commutator brushes of the control circuit only provide an effective transverse line of simultaneous contact with the patch 11 at a tape speed of lOOfeet per minute, a half-inch length of patch 11 will afford an impulse of A of a second duration to activate the sensing relay. Similarly, if the brushes were lengthened to provide a longitudinal band of'simultaneous contact of one-half inch, to provide an impulseof equal duration the patch 11 would need to be only long enough to provide a transverse line of contact.
As indicated diagrammatically in FIGURE 5, a spool of tear tape 30 and a roll of packaging film 33 are fed overguide rolls- 41 and 42 into the packaging machine 40; the tear tape passing through the control box 50."
The control box 50, as indicated in FIGURE 6, preferably contains two pairs of commutator brushes 51a and 51bc0nnected in parallel and engaging opposite sides of the tear tape ltl and the two brushes in each pair consituting relatively fine flexible feelers providing at least points of contact located transversely of the tape 10. Twopairs of-brushes engaging opposite sides of the tape 10-are employed in order to obviate any need for ascertaining whether the tape is fed into the packaging mavoltage, for a warning device, in this instance, a bell occurred.
55. The timer 53 maintains the relay circuits closed for whatever period of time is desired, say, ten seconds, whereupon the timer 53 opens the circuit holding the relays 52 and 54 closed and the control circuitry returns to its initial condition awaiting actuation by a patch 11 on a succeeding tear tape It). Alerted to the warning bell, the attendant has time to mount a new spool 30 and splice the tape 10 thereon to the tape running out of the exhausted spool. Instead of the bell 55, any other suitable warning device or system may be employed, as, for example, buzzers, flashing lights, or the like. Also, instead of or in addition to producing a visual or audible signal with the warning device, an automatic flying splicer may be actuated or a motor control unit for the packaging machine maybe actuated to slowthe packaging machine down, without bringing V the motor control unit, for example.
Where more than one web is fed into a packaging machine or other converting equipment, it may be desirable to provide more than one web with end control. Thus, as indicated in FIGURE 5, it is optional to provide a second control box 50 through which the packaging film web 33, if suitably equipped with a patch 11, may be passed. Where a web end control is provided for more than one web, each control may operate a separate warning device. In most instances, however, the control boxes will be connected in parallelto a single warning device, as indicated in FIGURE 5, so that it will be operated as any one of the several Web supply rolls or spools approaches exhaustion.
The actual cross-sectional configuration of the highly conductive patch 11 may be significant in that, as the brushes 51 are drawn over the very great length of the tear tape 10, there is the possibility that wax, plasticizers, gum, dust, and the like, may be picked up from the tape and accumulated on the brushes. If the patch were of no appreciable thickness, as might be the case if the patch were a thin film of conductive ink or like coating material, the control circuit might fail to operate because such accumulated soil would insulate the brushesfrom the patch. In actual use and testing of the tape disclosed herein, however, no such failures have It is suspected that the relatively sharp forward'edge of the'patch, being slightly raised with respect to the adjacent surface of the tapeand harder than the soil whichxmight accumulate on the contacting surface 7 ofthe brushes, serves to scrape any such accumulated reliability of photo-electric or other electronic sensing means having closed circuits which would be normally operating during the long intervals between warning signals.
This invention has been described with particularity as to its embodiment in a tear tape to be incorporated with a cellophane or similar film overwrap in automatic packaging machinery. The potential field of use of this invention is by no means limited to such specific packaging webs or converting machinery, but may be used with other Webs, such as roll stock constituting a Web handled in bag making or packaging machinery, printing machinery, re-wind machinery, and the like. The term Web as used in this specification is to be understood to constitute film and like flexible sheet materials having a substantially greater width than thickness and having so much greater length than width that the material is normally and most conveniently stored or handled by the art when put up in the form of rolls or Spools rather than as flat sheets or bundles of relatively fiat sheets.
Accordingly, it is to be understood that this invention is not to be limited to the particular embodiment disclosed but is to be subject to modification and variation within the scope of the following claims. Thus, for example, the webs for which the invention has been found particularly useful are organic packaging films, such as cellophane, polyethylene, saran, and the like having relatively high dielectric strengths and being substantially non-conductive when the gap between the brushes is bridged by portions of the web surface other than the surface provided by the patch. In some instances, however, the web itself, or printing or coating thereon, may be somewhat conductive but not as conductive as the patch so that some current may bleed more or less continuously between the brushes; or soil accumulating between the brushes, while offering resistance, may tend to short out the brushes to a degree; in such event the sensing relay or other sensing means is simply adjusted or selected to be responsive only to the substantial current pulse initiated when the brushes contact the more highly conductive patch. If the web itself has a highly conductive surface, in the case of metalized films or foils, then the patch is non-conductive and the sensing means responds to the change in electrical values eifected by the patch. If the web is a printed web having repetitive or successive conductive and non-conductive areas, then the patch may be provided with conductive and non-conductive areas to provide a particular code of impulses to which the sensing means is responsive; or the sensing means may be made responsive to changes in electrical values other than conductivity, such as a change in dielectric strength provided by the patch when the sensing means responds to changes in capacitance. It should also be understood that the patch is preferably but not necessarily located on one side of the web; the patch may in effect be a double patch located on opposite sides of the web and electrically connected or not as the particular sensing means may dictate. Still other variations and modifications will undoubtedly occur to those skilled in the art to meet the needs of specific webs While retaining the spirit and scope of this invention as defined in the following claims.
What is claimed is:
1. Apparatus for signaling the approaching end of a supply of tear tape to a packaging machine comprising a first pair of brushes and means to hold said brushes against one side of the tear tape as it is fed to a packaging machine, the spacing between the brushes being adjust able to a gap adapted to be bridged by a conductive patch adhered to the tear tape adjacent the final end of the tape, an impulse actuated holding relay in series with said brushes and a source of low voltage, whereby said holding relay will be actuated by an impulse initiated by the bridging of the gap between said brushes by the conductive patch, a timer device in the holding circuit of said relay, said timer normally closing said holding circuit but opening said circuit after a pre-deterrnined length of time, and a warning device actuated by said holding circuit while it is closed.
2. Apparatus as defined in claim 1, including a second pair of brushes connected in parallel with said first pair and adapted to engage the side of said tape opposite said first pair of brushes whereby said warning device will operate regardless of possible inversion of the side of the tape carrying the conductive patch.
3. Apparatus for warning of the approaching end of a web carrying a conductive patch adjacent its end comprising a first pair of brushes having a gap adapted to be bridged by a patch as said pair is contacted by the patch, a second pair of brushes adapted to engage the opposite side of the web and to have the gap therebetween bridged by the patch in case the patch is carried by the side of the web engaging said second pair rather than said first pair of brushes, a warning device, said first and second pairs of brushes being connected in parallel circuitry adapted to initiate operation of said warning device, whereby inversion of the side of the web carrying the patch is eliminated as a possible cause of failure of said warning device to operate.
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