METHOD OF AND APPARATUS FOR FORMING,

FILLING AND SEALING PACKAGES

Background of the Invention

This invention relates to methods of and appa- ratus for forming, filling and sealing packages, and more particularly to vertical form-fill-seal packaging methods and apparatus.

The invention is directed to the type of pack¬ age forming, filling and sealing in which flexible pack- aging material is formed into tubing and the tubing is fed downwardly along a mandrel and transversely sealed below ^" the lower end of the mandrel at package length in¬ tervals, a quantity of the product with which the pack¬ ages are to be filled being delivered down through the mandrel into the tubing during an interval of time be¬ tween successive sealing operations. It is more particu¬ larly directed to package forming, filling and sealing of the stated type, in which the film is pulled down on the mandrel by belts, as in my coassigned U.S. patent No. 4,288,965, issued September 17, 1981, entitled Packaging Method and Apparatus. Difficulties have been encountered in certain instances in the use of the vacuum belts dis¬ closed in said copending application, particularly in situations where a relatively high pulling force on the tubing was required, due to limitations on the vacuum which can be applied. Friction belts were substituted for the vacuum belts, but this led to the further problem that the pressure applied to the tubing by the friction belts tended to cause the tubing to stick to the mandrel in situations where the material had a relatively high coefficient of friction (low slip) on the mandrel.

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(Material used for certain products has a low slip char¬ acteristic on the face which is on the inside in the packaging operation.) Efforts were made to prevent such sticking by trying various anti-friction coatings on the mandrel, such as Teflon and high density polyethylene, but even these measures were not always successful. For example, the anti-friction material tended to rub off in a relatively short time. Anti-friction rollers have been used but are unsatisfactory in situations where they may become jammed by dust from the product being packaged.

Summary of the Invention

Accordingly, among the several objects of the invention may be noted the provision of a method of and apparatus for forming, filling and sealing packages of the class described having an improvement for effectively reducing friction between the tubing and mandrel to pre¬ vent the tubing from sticking to the mandrel; the provi¬ sion of such a method and ^' apparatus enabling use of pack¬ aging material which has a low slip characteristic on its face which is on the inside in the packaging operation; and the provision of such a method and apparatus enabling use of friction belts for feeding the film along the mandrel without causing pressurized engagement of the tubing and the mandrel such as would tend to make the tubing stick to the mandrel.

In general, the method and apparatus of this invention are applied to the forming, filling and sealing of packages wherein flexible packaging material is formed into tubing and fed along a mandrel, and are σharacter- ized in that air is blown between the mandrel and the tubing to air-float the tubing on the mandrel.

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Other objects and features will be in part apparent and in part pointed out hereinafter.

Brief Description of the ^' Drawings

Fig. 1 is a perspective of a vertical form/ fill/seal machine embodying the invention;

Fig. 2 is a front elevation of. Fig. 1, showing certain drive mechanism of the machine;

Fig. 3 is a side elevation of the lower part of

Fig. 2; Fig. 4 is an enlarged horizontal section on line 4.—4 of Fig. 2;

Fig. 4A is an enlarged fragment of Fig. 4; Fig. 5 is a diagram of a control circuit; and Fig. 6 is an enlarged fragment of Fig. 2 with parts broken away and shown in section.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

Description of the Preferred Embodiments Referring first more particularly to Figs. 1-3 of the drawings, the invention is shown as incorporated in a vertical form-fill-seal apparatus 1 such as shown in my aforesaid coassigned U.S. patent No. 4,288,965, in which a web W of flexible packaging material is pulled from a supply, fed over means 3 for forming the web into tubing T, product to be packaged is provided (in. any of various suitable well-known ways) in the tubing, and sealing operations are performed on the tubing as gen¬ erally indicated at 5 (again in any of various suitable well-known ways) to seal it to form packages. The pack-

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aging material may be a composite material having a rela¬ tively low slip (relatively high friction) characteristic on its face which is on the inside in the packaging oper¬ ation, for example, and the supply may be constituted by a roll R of the film suitably supported as indicated at 7. The forming means 3 may be a forming shoulder gen¬ erally of a conventional type such as shown, for example, in the coassigned U.S. patents 3,050,906 issued August 28, 1962, 3,449,888 issued June 17, 1969, and 3,664,086 issued May 23, 1972. As shown in Figs. 1, 2 and 4, the forming shoulder 3 forms'the web of packaging material into the tubing T with the longitudinal margins 9 and 11 of the web W in lapping relationship, and directs the tubing downwardly around a vertically extending, hollow mandrel 13. As illustrated, margin 9 is on the inside, margin 11 on the outside. At 15 in Fig. 1 is diagrammatically indicated suitable means for sealing the lapping margins 9 and 11 of the web to form a longitudinal s'eam for the tubing. Product is provided in the tubing T via the hollow mandrel 13 in suitable conventional manner, and the tubing is transversely sealed at package length intervals by the sealing means indicated at 5 below the lower end of the mandrel. The sealing means 5 may, for example, comprise a pair of sealing bars each designated 17 operable in a fixed horizontal plane below the lower end of the mandrel to form a top seal for the package being completed and the bottom seal for the next package to be formed. The seal bars may have cutting means incorporated therein (as is conventional) for cutting

transversely between the seals made at 5 to separate the completed package P from the tubing. In the embodiment illustrated, the tubing is intermittently fed forward, which is downward, one package length increment, the seal bars 17 being open. The tubing dwells between successive feed cycles, the seal bars being closed on the tubing for the transverse scaling operation during each dwell. Suitable means, which may be wholly conventional and well known in the art, is used for moving the seal bars toward and away from one another.

The web W is intermittently pulled from supply roll R ^* , measured for each sealing operation at 5, and fed forward toward the forming shoulder 3 by means indicated generally at F located between the supply roll and the forming shoulder. This means F is. intermittently oper¬ able to apply a forward force to the web at a position between the supply roll and the forming shoulder for feeding the web forward one package length increment in a given interval. Thus-, it acts as a web feeding and mea- suring or metering means. As illustrated, it comprises a lower roll 19 and an upper roll 21 with means indicated generally at 23 for intermittently driving these rolls through a predetermined interval corresponding to the desired length for the packages to be formed to feed the web forward one such increment. As shown in Fig. 2, the driving means 23 comprises a continuously operating electric motor/speed reducer unit 25 driving the input of an electric clutch/brake unit 27 via gearing indicated at 29, the output of the clutch/brake unit being connected to the lower roll 19 as indicated at 31. The rolls 19 and 21 are geared together as indicated at 33. The

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clutch of unit 27 is adapted intermittently to be engaged and the brake of unit 27 disengaged for driving the rolls 19 and 21 to feed forward the requisite package length increment of web W on each feed cycle by a suitable pro- grammable control 35 which is under the control of an encoder 37 (see Fig. 5) , the clutch being disengaged and the brake engaged to terminate the feed cycle and remain¬ ing so for the dwell of the web W and tubing T, the clutch then being engaged and the brake disengaged for the next feed cycle.

The web travels from the measuring and feed¬ ing rolls 19 and 21 under a guide roll 38 and thence up to and around forming shoulder 3. The increment of the web W fed forward by the measuring and feeding rolls 19 and 21 is taken up and pulled over the forming shoulder 3 under tension by tubing feeding means indicated generally at 39 in Figs. 1 and 2 below (downstream from) the form¬ ing shoulder. This tubing feeding means 39 acts to apply a forward (downward) .force to the tubing T, separately from the application of force to the web W by the rolls 19 and 21, and externally of the tubing, at a rate such as to pull the web over the forming shoulder 3 under, tension to maintain the web taut. In this regard, the tubing feeding means tends to draw the tubing down (for- ward) on the mandrel 13 a distance greater than the pack¬ age length increment in the stated interval of operation of the rolls 19 and 21. The draw-down force on the tubing is relatively low. While means 39 tends to draw the tubing T down a greater distance than the package length increment, the tubing is drawn down only a dis¬ tance corresponding to the package length increment (the

tension is insufficient to stretch it to any substantial extent) , and the package length increment of the web W metered out and fed forward by the rolls 19 and 21 is thereby taken up and pulled over the forming shoulder 3 under tension, with the tension substantially uniform for proper tracking of the material over the forming shoulder.

The tubing feeding means 39, as illustrated, comprises a pair of endless belts, and more particularly a pair of rubber belts each designated 41 at opposite sides of the mandrel 13 (i.e. at 180° intervals around the mandrel) for frictionally engaging the tubing to feed it downward. Each belt is a flat belt trained around an upper pulley 43 and a lower pulley 45 and so arranged as to have a downwardly movable inner reach 41a frictionally engageable with the tubing T at the respective side of the mandrel 13. Each belt may, for example, comprise a resilient surface layer of rubber on a suitable backing, and the rubber layer may have a plain or textured outside surface. The belts 41 are operated intermittently for feeding the tubing T downward on the mandrel 13 concur¬ rently with each operation of the web feeding rolls 19 and 21. The belts may be started in operation generally at the same time or somewhat before the rolls 19 and 21 start feeding the web W. They are operated ^* at such a rate relative to the rolls 19 and 21 as to tend to feed the tubing downward at a rate faster than that at which rolls 19 and 21 feed the web forward, and may be stopped generally at the same time or shortly after the rolls 19 and 21 stop. Means for operating the belts in this manner is shown to comprise a gear drive 59 from the

S electric motor/speed reducer unit 25 to the input of each of a pair of air-operated slip clutches each designated 61, with individual drive trains as indicated at 63 from the outputs of the slip clutches to the upper pulleys 43 for the two belts 41. The slip clutches 61 are under control of an air valve 65 (Fig. 5) which is in turn controlled by the programmable control 35. The latter functions to actuate (engage) the slip clutches 61 to start driving the belts either at the same time or some- what before the electric clutch/brake unit 27 is actu¬ ated, and to maintain the slip clutches engaged for - driving the belts until the electric clutch/brake unit 27 is deactuated or somewhat thereafter, the slip clutches then being deactuated to stop the belts. While engaged, the slip clutches permit slip in the drives from the unit 25 to the belts.

In the operation of the apparatus, the motor/ speed reducer unit 25 is operated -continuously. - The clutch/brake unit 27 is actuated (i.e. its clutch is* engaged, its brake disengaged) in timed relation to a function of the apparatus such as a filling function, the encoder 37 being operable to signal the programmable. control 35 to actuate the unit 27 to start driving rolls 19 and 21 to unwind the web W from the supply roll R and feed it forward at the appropriate time (e.g. when a scale has weighed out the quantity of product to be delivered for a package, and has dumped the product for delivery down through the mandrel 13 into the tubing T) . The unit 27 remains actuated for an interval such as to cause rotation of the rolls 19 and 21 to feed forward a

package length increment of the web, and is then deactu¬ ated. The interval .may be determined and controlled via the programmable controller 35 or by means of an optical scanning system operating in conjunction with registra- tion marks at package length intervals on the web in the case of preprinted web, or by means measuring the rota¬ tion of the rolls 19 and 21 in the case of unprinted web, or in other suitable manner well known in the art.

The programmable control 35 operates to actuate the valve 65 for engag-ing the slip clutches 61 to start driving the belts 41 either at the same time or somewhat before the rolls 19 and 21 start feeding the web W for¬ ward toward the forming shoulder 3. Thus, when the rolls 19 and 21 operate to feed the web forward, the belts are in operation and act to draw down the tubing T formed as the web passes over the forming shoulder 3. The drive for the belts is such that they tend to travel at a rate greater than the rate at which ^' rolls* 19 and 21 feed the web forward. For example, they may tend to travel at a rate about 10% greater than the rate at which rolls 19 and 21 feed the web forward (that is, the belts if wholly free of any restraint would travel a distance 10% greater than the amount of web released (i.e. fed forward) by rolls 19 and 21. However, the tubing T cannot advance any faster than the rate at which rolls 19 and 21 feed the web forward without stretching (the web being caught in the nip of rolls 19 and 21) and the pull exerted by the belts on the tubing does not cause any substantial stretching. Hence, the belts travel generally at a greater rate than the web and, in tending to travel faster than the web, exert a downward pull on the tubing T to tension it and thereby pull the material over the forming shoulder 3 under tension to maintain the web taut.

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At the start of the downward feed of the tubing T, the seal bars 17 are open, and remain open throughout the downward feed of the tubing off the lower end of the mandrel 13. When the rolls 19 and 21 have measured out and fed forward one package length of web W, and the belts 41 have drawn the tubing T down one package length on the mandrel and fed one package length of the tubing T off the lower end of the mandrel, the clutch/brake unit 27 is deactuated to stop the rolls 19 and 21 and thereby stop the forward feed of the web, for the dwell of the web and the tubing for the sealing operation. The slip clutches 61 are deactuated either at the same time as the rolls 19 and 21 stop, or slightly thereafter. When deactuated, the slip clutches may be wholly disengaged so as to stop drives 63 to the belts 41, or they may remain lightly engaged to exert a light drive via 63 on the belts so that the belts exert a light draw-down force on the tubing to maintain tension in the tubing. With the tubing T stopped, and with product in the tubing above the transverse seal at the lower end of the tubing (this seal being one package length below _^ the seal bars at 5 and constituting the bottom seal for the package to be completed) the seal bars are closed on the tubing to form the top seal for the package P being com¬ pleted and the bottom seal for the next package to be formed. The seal bars then open, and rolls 19 and 21 and belts 41 are operated through the next feed cycle.

In accordance with this invention, air is blown between the mandrel 13 and the tubing T to "air-float" the tubing on the mandrel, thereby substantially to

reduce the friction of the tubing on the mandrel (even in the case of low slip material). The air is blown against the inside of the tubing T in the regions of the inner reaches 41a of the belts 41 at opposite sides of the mandrel, and not only maintains the tubing slightly spaced from the mandrel by a thin film of air between the mandrel and the tubing, particularly at the belts, but also pressurizes the tubing against the inner reaches of the belts to increase the frictional engagement between said reaches and the tubing for a stronger pull of the belts on the tubing.

The means for blowing the air is indicated generally at 71. It comprises plenum means and more particularly two plenums in the mandrel, one for each belt and each designated 73, positioned at diametrically opposite sides of the mandrel 13 adjacent its lower end in the regions of the inner reaches 41a of the belts, and means comprising two air lines 75, one for each plenum, for delivering air under pressure to the plenums, air flowing out radially from the plenums through orifices indicated at 77 against the inside of the tubing T where the inner reaches 41a of the belts engage the tubing.

Each plenum is of elongate narrow shallow box form, having elongate inside and outside walls 79 and 81, elongate side walls each designated 83, and upper and lower end walls 85 and 87. The outside wall 81 is longer and wider than the inside wall 79, thereby providing a flange 89 projecting outwardly all around the plenum, and each plenum is secured in a vertical slot 91 in the mandrel 13 at the respective side of the mandrel with this flange engaging the outside of the mandrel all

around the slot. The outside wall 81 of the plenum is curved to conform to the circular shape of the mandrel and is relatively thin so as not to protrude substan¬ tially beyond the outer surface of the mandrel. The outside wall 81 has a series of air exit holes 93 there¬ in, these holes being on a line extending lengthwise (vertically) and centrally of the outside wall. A thin plastic (e.g. polyethylene) membrane 95 is applied to the inside-of the outside wall 81 and has the air orifices 77 therein in register with the holes 93 for the discharge of air from the plenum. The membrane may be 0.020" thick and the orifices may be 1/64" (0.4 mm) in diameter, for example. The orifices are centered with respect to the holes, which may be 1/16" (1.59 mm) in diameter, for example.

The air lines 75 extend down through the man¬ drel 13 from the upper end of the mandrel to the upper ends of the plenums 73. The plenums and air lines are at opposite sides of -the mandrel on the inside of the man- drel and generally out of the way as much as possible of product delivered down through the mandrel in the pack¬ aging operation.

Air is continuously delivered to the plenums 73 while the apparatus is in operation and blows out through the air orifices 77 and holes 93 continuously to provide an air cushion as indicated at 97 in Figs. 4 and 4A be¬ tween the mandrel 13 and the tubing T. The flow of air out of the plenums is relatively low, on account of the use of the membrane 95 with the relatively small (e.g. 1/64" (0.4 mm) diameter) air orifices 77. The air, in being confined to some extent between the outside walls 81 of the pie- nu s 73 and the tubing all along the inner

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reaches 41a of the belts, compresses the resilient rubber layers of the belts so that the faces of the inner reach¬ es are spaced outward from the outside faces of the walls 81 of the plenums a distance slightly greater than the wall thickness of the tubing, with the dual result that the tubing is air-floated on the mandrel for reduced friction of the tubing on the mandrel (particularly at the belts) and for enhanced friction between the belts and the tubing for enhanced feed of the film by the belts. It is to be understood that, generally, the inner reaches 41a of the belts are contiguous to the outside faces .of the plenum walls 81 in the absence of the tubing T on- the mandrel. Thus, compression of the resilient rubber layers of the belts in the inner reaches of the belts is utilized to obtain the spacing for the air float of the tubing. Generally, the air passes upwardly be¬ tween the mandrel and the tubing and escapes from between the mandrel and the tubing at the upper end of the tubing. In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above constructions and methods without departing from the scope of the invention, it is intended that ^' all matter contained in the above description or shown in the ac¬ companying drawings shall be interpreted as illustrative and not in a limiting sense.