AU595332B2 - Method and apparatus for form-fill-seal packaging of articles - Google Patents

Abstract

A flat, flexible film web (2) is drawn off from a stock roll (3), moved over a forming shoulder (12) and thus formed into a tube (20). A longitudinal seam is made on the tube (20), the product to be packed is introduced and the package is sealed by transverse seams (17, 21). The film web (2) is driven continuously by means of drive rollers (7). The longitudinal and transverse seams are produced as the tube is being continuously advanced. A photocell (19) is used to scan printed marks on the film web (2) and a correcting means in the drive of the transverse welding jaws (40, 43) prevents the possibility of inaccuracies in the pack division being added. <IMAGE>

Description

FORM COMMONWEALTH OF AUSTRALIA PATENTS ACT IS52-69 COMPLETE

SPECIFICATION

FOR OFFICE USE: Clas~s Applicatio-~ Number: Lodged: lit. Cliss pOe~plete Specification Lodged: Accepted: Published: Priority: Related Art: E i 1 oni 49 and L N&i of Applicant: Address of Applicant Actual Inventor; ILAPAK RESEARCH fDEVELOPMENT S.A.

Via Granc.%4a, Zone Switzerland Industriale, CH-6011 Grancia-Lugano, Wolfgang KLINKEL and Dieter VITS Address for Service: Sheiston Waters, W8Clarence Street, \$'ydney Complete Specification for the Invention entitled: "METHOD AND APPARAT'US FOR FORM-FILL-SEAL PACKAGING OF ARTICLES" The following statement is a full description of this invention, lnc~adlng the be~st nothod of performing it k~nown to me/us:- 1 -6 13 THE CLAIMS DEFINTNG THE INVENTION ARE AS FOLLOWS: 1. method Zor form-fill-seal packaging of articles including i METHOD AND APPARATUS FOR FORM-FILL-SEAL PACKAGING OF ARTICLES The present invention relates to packaging -aterials in flexible bags, typically plastic bags, which are made as the product is being filled into the bags by supplying a web of plastic film to a former which shapes the web into a tube wich is then sealed longitudinally, filled, and sealed transversely.

Form-fill-seal packaging of articles is known; the usual way is to provide a film of plastic material, passing the film around a former to wrap the film longitudinally, for example SI.about a mandrel, tube or the like, to form a tubular structure w ith a vertical seal. The tubular structure is cross-sealed by a cross-sealing apparatus, for example by welding, sealing or the like, usually under heat, by passing the tube between S a pair of heated sealing jaws.

The tube is filled and the filled tube portion is closed.

The tube is servered, and the now sealed package can be discharged in a bin. Processes and apparatus to such form-fill-sealpackaging apparatus as previously known operate intermittently.

.1 2 In such system and apparatus, a web of film is drawn off a supply roll, the length of the web corresponding to the required length of the package. Upon forming the film .into a tube, the longitudinal and transverse seals are made, while a film portion which will form the package is stationary. Such intermittent operation places stress on the transport of the film which is moved, in steps. The film web is, thus, undesirably differntially stressed, the production output is limited and motor controlling and web guiding problems are existing.

It is an object to provide a form-fill-seal packaging apparatus and method which operates continuously, in other words, which permits continuous manufacture of sealed and filled packages which have higher output than previously known apparatus. Film is not stressed because of continuous speed and continuous web guiding. Ready change of the length of the packages is permitted and occurance of cumulative feed errors is avoided.

This is particularly important if the packages have printed information thereon so that, when the packages are finally supplied, the printed information or advertising material or the like will fall between the seamed ends, where it is desired.

e Briefly, spaced markers are placed on the film, ar.

the film is continuously positively fed to the t former.

A pulling force is continuou''y exerted on the tube which is longitudinally seamed. The spaced markers on the film are scanned, for example optically, and the length between the spaced markers is compared with a predetermined command length, for example by comparing the time between the occurance of Sspaced markers as the film is being fed with predetermined speed. The time intervals or time periods can readily be determined by counting of clock pulses, signals or impulses generated by a computer apparatus. The feeding speed of the film supply is then controlled, in synchronized relations, with the operation of the cross-sealing element, as well as with a sealing drive unit which, continuously, moves the sealing jaws downwardly as the form-fill-seal packaged articles is being moved under prior control of the film feeding element.

.1.

-3 By comparing the length increment, or time between markers with a command value, or command time, respectively, a deviation can be determined and the feeding speeds controlled to compensate for any deviation which may be found, so that the feeding speeds, sealing speeds and fi2'ing speeds can all be matched to each other.

The system and method has the advantage that all necessary operations, such as forming of a longitudinal film seal or overlap seal, filling of the product in the interior of the formed bag, generation of cross seams or seals, and severing of the filled packages can be carried out as a continuous process and during continuous supply of the film from a film supply, such as a film supply reel.

Further printed subject matter on the packages will always appear at the same relative position with respect to cross seals, and in accordance with the desired alignment.

Errors in positioning of the seals, for example with respect to printed subject matter, are readily avoided, and will not become cumulative.

Other objects, features and advantages will appear hereinafter as the description proceeds.

Fig. 1 is a general side view of the form-filling and sealing packaging machine, omitting elements not necessary for an understanding of the invention, and designed for vertical installation, for fill in downward direction; Fig. 2 is a front view of the apparatus, partly cut away; Fig. 3 is an enlarged fragmentary view of the drive for the film as it is being formed into a tube; Fig. 4 is a fragmentary, part-sectional view through the drive of the cross-sealing jaw; m i -a.

-4- Fig. 5 is a schematic drawing of the operation system of the machine, illustrating electrical connection; Fig. 6 is a block diagramm of the control system of the machine.

The form-fill-seal packaging apparatus see Figs. 1 and 2 is used, primarily, to fill a tubular bag formed from a flat, flexible film 2. The flat film 2 is, typically, a flat, flexible plastic foil web or film, for example heatsealable polypropylene, weldable polyethylene or the like. The film 2 is drawn off a supply reel 3. The supply reel 3 is located on a machine frame 4, on suitable bearings, to be supplied as needed. A dancer compensating roller arm 5, known as such, is pivotably supported on the frame to form a variable film supply loop. The film 2 is then guided over a plurality of deflection rollers 6 to a pair of drive rollers 7. The drive rollers 7 are driven by suitable sprocked chains or other .0 similar drives from a motor 10 which, preferably, is a servo S: motor or a stepping motor so that its speed can be accurately 6:6 controlled. The drive roller pair 7 thus draws the film web :0202 from the film reel 3 and supplies the film web 2 to the apparatus downstream, of the drive roller pair 7.

00 The film web 2 is guided over a former 12, of known and standard construction, to be formed into a longitudinally, vertically directed tube 20 surrounding a filling tube 13 on 0 the outside ther!>.,Qf. Preferably, the filling tube 13 is cylindrical and of circual cross section. The upper end of filling tube 13 is in, communication with a fill funnel 14. Products suh a powergranulat or chips introduced intotefnl 14 in the direction of the arrow B3 (Fig. 1) can be filled within packages to be formed; a predetermined quantity, by weight, volume, number or the like, in accordance with well known proportioning apparatus, will provide the charge of the products to be tilled into the respective packages. Frequently, the charge to be filled into the packages may be determined by ab -4 74 193/87 weight. Filling arrangements other than the fill funnel 14 as shown may be used.

A longitudinal seal jaw or apparatus 15 forms a longitudinal seal or weld 16. The longitudinal apparatus for welding or sealing is movable vertically as a unit. The sealing operation is carried out continuously during continuous feed of the web 2 and the then formed tube 20. The longitudinal sealing jaw or other sealing or welding apparatus 15 carries out a movement which is shown in patent application No. 67 403/87. During the sealing process in which a vertical, linear seal is generated the sealing element 15 moves continuously and with the same linear speed as tube 20 in accordance with the downwardly directed movement, see arrow R of Fig. 1. At the end of the stroke, and as the longitudinal seal 16 has been formed at the circumference of the tube 20, the jaw 15 is lifted off the tube 20, and returned upwardly while keeping some radial distance from the tube 20. The upward movement is about three times faster than the downward movement of the tube 20. Since the jaw 15 has a definite length dimension in longitudinal direction, a continuous seal can be formed. The vertical seals made by the jaw 15 overlap each other to form a continuous **o vertically seal. The overlapping area is preferably about Movement of the jaw 15 is preferably generated by a multiple bar linkage drive.

The longitudinal seal generated by the longitudinal sealing jaw 15 is shorter than the length of the packages.

Thus, the stroke per unit time or the rhythm or cadence of operation of the longitudinal jaw 15 must be substantially faster than the stroke time or cadence of operation of the transverse sealing jaw 40, 43.

S

The drive of the motor 10, wiiich is coupled to the drive roller pair 7 and 'o movement of the welding jaws 15, insures that the sealing jaw 14 and the feed of the film 2 and hence of the tube 20 will be in synchronism.

ILL~I iljl-.L- Ldi- C L_ it -6- Rather than using a multiple bar linkage it is also possible to use other arrangements, for example by moving the longitudinal jaw 15 by different drive elements, for example cams.

Two draw down rollers 25 are located diametrically opposite each other with respect to the fill tube 20 to provide for gentle draw down of the tube 20 over the former 12 and along the tube 13. The draw down rollers 25 are driven at a speed which is higher than that of the drive roller pair 7 provided from motor 10 to maintain the film taut.

Thus, some slippage will result. To accomodate the slippage, a slip coupling is interposed between the drive to the rollers 25 and the inside drive mechanism for the draw down rollers The rollers 25 have the tendency to rotate with higher circumferential speed than the feed of the tubes and, consequintly, slip will occur.

The rollers 25 are pressed radially inwardly to engage the tube 20. To provide for easy exchange or refeeding of film, the rollers 25 can be pivoted away from engagement with the fill tube 13.

*A cross-sealing apparatus is located downstream of the longitudinal sealing apparatus and beneath the range of movement 0 of the jaw 15. The cross-sealing apparatus is formed of two jaws 40, 43 (Fig. 4) which, simultaneously, form a bottom seal for a new bag, as well as a top seal for an a ready filled upper bag 54 (Fig. The upper top seal 17 (Fig. 1) thus S is formed simultaneously with the closing seal 21 for the previously filled and still open tube, so that the initially completed open tube is sealed twice by two parallel spaced seals. As best seen in Fig. 4, a severing knife 72 is provided to separate the material of the tube 20 between the two seals, t^ -7to therby separate the filled bag from the tube which has been supplied with a bottom seal.

In accordance with a feature of -the invention, and since the feed of the tube 20 is continuous, the welding ja-.ws 43 and all cooperating elements, such as the motor 62 and the knife 72, move continuously during the sealing process, and w-th the same feeding speed as the tube feed speed.

A ver-Lical system 56 (Pig. 4) is provided, supporLing the jaw 40, 43, and moving the jaws up and clown in accordance with the double arrow F (Fig. Drive motor 58 is coupled to a rack 59 which is driven by a pinion of the motor shaft 58, engaged with 4 vertical guide 60. Alternatively, the rack can be formed as a spindle on which a spindle nut is located.

Depending on the direction of rotation of motor 58, the system 56 is moved vertically upwardly or downwardly. The system 56 0 includes a motor 62 (Fig. 1, 4) which drives a cam disk 76 over a suitable reduction gearing 62a. The cam disk 76 is engaged by a cam follower 82 which controls the opening and closing movement of the jaw 43, Jaw 40 is moved in opposite direction in known manner by counter-operation members. The cam follower 82 engages the cam dis~k 76 which is coupled to a shaft 78. The cam follower 82 is coupled to the rod 80, at the end of which the welding jaw 43 is located. Upon rotation the cam disk 76, jaw 43 will move in the A.rection of the double arrow K of Fig. 1.

The two jaws 40, 43 have upper and lower portions -see Fig. 1 and 4 which are heated electrically to sealing or welding temperatures, respectively, and to form, simultaneously, with the upper portion of the jaw 43 a bottom seal of the tube 20 and, with the lower portion of the jaw 43, a top seal for the already filled bag 54. The tube portions c' the jaws 40, 43 are spaced from each other, so that the closing seal 17 (Fig. 1) of the already filled bag 54 is generated simultaneously with the bottom seal 21.

MW

-8- Sealing and severing structures are known, and may bc in accordance with any suitable construction. A prefered structure, which also piovides for control of the sealing pressure, is described in application No. 53 637/86.

In accordance with a feature of the invention, the tube is fed continuously. In synchronism therewith, the entire system 56 is fed at the same tube feed speed in the direction of the arrow R (Fig. 5) downwardly,. as the long seal is being made. The sealing jaws 40, 43 are closed at the upper end position of the system 56 see Fig. 1 and thus, during the sealing process, the closed sealing jaws 40, 43 move with the feed speed of the tube 20 downwardly. The welding stroke in vertical direction of the sealing jaws 40, 43 upon engagement with the film tube 20 is shorter than the vertical length of the bag 54. At the same time, the goods to be packaged are filled through the fill funnel 14 into the interior of the o fill tube 13, and, in measured quantity, are supplied to the tube 20 as it moves downwardly and along the fill tube 13.

*....Before the lower end position of the system 56 is reached, and during downward travel, severing knife 72 (LPig.4) will be operated, so that the finished and closed bag 54 will fall in the direction of the arrow R (Fig. 1) to be discharged.

The pulse to operate the severing knife 72 can be provided after the sealing jaws 40, 43 have closed, with some time delay, .*that is, based on timing of the operation of the s2aling jaws the seal itself, or as a function of the position of the system along the height of the apparatus. Admission of pressure fluid to operate the knife 72 can be controlled electrically or by a cam or the like, as desired.

When the system 56 has reached the bottom position, jaws 40, 43 open based on suitable rotation of the cam disk 76, or a crank of other control apparatus. The direction of rotation of the drive motor then is reversed and its upward speed is increased, so that the system 56 is again moved to starting position.

9- Rather than operation the jaws 40, 43 by a crank or by a cam disk 76, hydraulic or pneumatic cylinder-piston units can be used controlled, for example, by electromagnetic valves.

To compress contents within the tube 20 which may be of light weight, such as potato chips, and high bulk, it is desirable to shake the sides of the bag laterally by a shaker arm 51 which osciallates horizontally, as shown by the double arrow H (Fig. 1).

Sy'nchronized operation of the various elements of the overall feeding system is controlled by an electrical control system, shown in detail in Figs. 5 and 6, The drive roller pair 7 continuously removes the film 2 from the film reel 3. The motor 10, which is a servo motor *Gge or a stepping motor, is speed-controlled by a control unit 84, which controls motor controllers or control unit 88 associated with the individual motors. A motor power supply or power source 87 provides the necessary operating power.

The motor controller may be a driver circuit, A sensor 19 which, preferably, is a photo cell, for example a photo transistor or other photosensitive element, is located between the pair of drive rollers 7 and the former 12. Phe sensor 19 responds to differences in brightness or whether an element is transparent of opaque and, thus, responds to marks on the .'film 2. Rather than providing marks on a film web, perforations or other indicia of posit~on of a specific transverse portion of the film can be used. The space between twc markers 53 *.:correspond to a predetermined space associated with each other 0:090: of the bags 54; of course, a plurality of markers may correspond to any such length, and the number of markers which are to be used on any one bag can be varied, as desired. Upon change of the length of the package, it is a zimple matter to provide for match of the markers signals sensed by the sensor 19 to the requisite package length, by digitally processing the time interval between succeeding markers, in relation to a fixed clock or signal frequency, or in relation to the linear speed of the film web 2, which can be readily determined from the rotary speed of the drive roller pair 7 together with the diameter thereof.

The length increments of the film between two markers 53 correspond to a predetermined number of pulses, signals or rotary incremental steps or angular rotation carried out by motor 10. If motor 10 is a servo motor operation in analog mode, the length increments will control the rotary angle through which the servo motor will turn; if the motor 10 is a stepping motor, the length between two markers 53 will determine the number of steps or impulses in time unit, and hence the entire anqular rotation of the motor.

The step or pulse number which the motor should carry 6 out to ffeed the film to provide the packages of predetr'rmined length is calculated and/or computed by a computer 90 (Fig. 6) w ith the number of pulses which occur in the period of time 4 .0' between scanning of two adjacent markers by the photo cell 4 tv 19. Upon deviation of the scanned or actual pulse number from the command or present value, the motor controller 86 is controlled to either suppress pulses so that the motor will run slower, or increase the number of pulses to increase the motor speed. The corrected values are supplied to motors 58 and 62 as well as to servo motor 10, so that the motor will operate in synchronism. The term "synchronism" as used herein is to be understood that the motors operate in synchronous relationship with respect to each other; the individual spoed in revolutions or angular deflection of each motor, per unit '.time, need not be the same; rather "Synchronous rclationship" ~~means that if the speed of the motor 10 changes, the speed or angular rotation per unit time of the motors 58 and 62 changes in propor-tion.

A

11 The control system provides for synchronized, conjoint operation in vertical direction of the jaw 15, in cadence with feed of the film and hence of the tube 20, as well as for opening and closing movement of the jaws 40, 43 during the sealing and welding which, in turn, is in synchronism and cadence with the separating distance defining the length of the packages and, also with the spacing between sequential markers. Inaccuracies in feed of the film, for example due to slippage of the film, tolerances in film thickness and the like, thus cannot become additive, and are immediately corrected within the inertia of the system, which is small.

The motors 58, 62, each, have a motor controller 86 and a pulse generator 88 connected therto, the pulse generators 88 providing the operating pulses for the motors 58, 62.

The sealing jaws 15, 40, 43, shown only schematically in Fig. 6, are each supplied from a sealing jaw power supply unit 94 and their relative temperature are scanned and supplied to an analog/digital convertor 96. The output ij fed back digitally to the computer 90 to form a close lap.

o S 2Q" The input of control unit 84 and computer 90 proferably, are a microcomputer suitable progralmm~e, oc carry ouc the respective operating functions. A co and display uihi 65 provides for data nwous !'he t or ,o control unit 84, and display of. reasectiv(. -ca being into the input or cont ol unit 84 ar 4, t*hetirttr, continued display of operating oharactoristics of the unit, to provide for monitoring of the respective elements.

In one embodiment, the unit 84, is p.:'eorably an

C.

opto-isolated digital input unit, with analoq/4dital' conversion capability, and receiivs, among other i putp, the input from sensor 19. Clock pulses ate V iidled blf the computer 90 which can be in forim F control unit with its own clock source s conventional for the control unit. By rming control unit 84, 90, the speed of the jaw the sealing ~ar~r ;i 12 jaws 40, 43 and the timing thereof can be controlled in time relation to the vertical movement of the system 56.

The unit 84 and computer 90 controlled by the command panel can be programmed as well known in connection with timing sequences and comparison technology.

Rather than making heat seals, welding seals can be made on the packages, both in longitudinal as well as in transverse direction, depending on the material of the film to be used. The jaws 15, 40, 43, thus, can be adapted, 1Q as desired, to the material and may be either sealing jaws for heat sealable material or welding jaws for thermoplastic materials.

The connection between the respective pulse generators 88 and the motors 10, 58, 62 is illustrated merely in the form of five lines, although, of course, more or fewer numbers of lines can be used.

The motors 58, 62 are reversible-type motors to provide, respectively, for reciprocating vertical movement of the jaw 40, 43.

Various changes and modifications may be made, and features described in connection with any one of the embodiments may be used with any of the others, within the scope of the inventive concept.

*a 0* o•

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W e r i 1,

Claims (6)

1. Method for form-fill-seal packaging of articles including providing a continuous, flat, flexible film; passing the flat, flexible film around a former to deform and shape the flat film into tubular shape in which lateral edge portions of the film will be located adjacent eacn other; connecting the longitudinal edge portions of the film while in tubular shape, to form a closed tube with a longitudinal seal; forming two spaced cross seams across the closed tube by sealing or welding means; filling the tube after having been cross-sealed by one of said seals; severing the tube between the cross seals, OG0 characterised by continuously ?ositively feeding the flat film to the former by continuous, moving a feed drive; continuously positively exerting a drawing force on the tube by continuously drawing the tube over the former to maintain it taut; moving the longitudinal sealing means with the same speed of the tube as it is drawn from the former during continuously moving said tube; moving cross-sealing means in a vertical direction with the same continuous speed as the tube; scanning spaced markers on the film, as it is being continuously fed, by a scanning means; comparing increments of the film trinsport between two successive markers with a predetermined command reference value, adjusting deviations of the film transport in order to prevent accumulated feeding of the tube.

2. Form-fill-seal packaging apparatus having means for SR4 providing a continuous, flat, flexible film; a former receiving said flat, flexible film and deforming 14 C* CC f o s C. S 0 C 0. 0.0.. C said flat, flexible film into tubular shape, with lateral longitudinal edge portions of the flat film located adjacent each other; means for sealing or welding the longitudial edge portions of the film, while in tubular form, to form a longitudinal tube with a longitudinal seal, and moving the longitudinal sealing or welding means with the same speed of the film as it is drawn from the former during continuously moving; means for drawing said film over the former and maintaining it in taut condition; cross-sealing means for forming spaced cross seals across the tube; means for filling the tube after having been cross-sealed by one of said cross seals; means for severing a filled tube portion from the closed tube; characterised by the fact that said apparatus comprises continuously operating positive feeding means for continuous feeding the film to the former and pulling the then formed tube from the former; drive means for said longitudinal sealing or welding means for continuously moving said sealing or welding means as the film is being fed to the former; drive means for said cross-sealing means for moving longitudinally the cross-sealing mesans with the same velocity as the film upon closing of said cross-sealing means on the film tube, and for repetitively moving said cross-sealing means in a return path out-of-engagement with said tubing and counter the continuously feeding direction of said tube; a scanning means for scanning markers on the film as it is moved past the scanning means; and control means including comparator or computer means coupled to said scanning means and said continuous positive film feeding means, said sealing means drive means and controlling movement of all said connected means, as a function of comparison of the spacing of S. C I 15 sensed marker with respect to a predetermined reference.

3. The apparatus of claim 2, wherein said comparator or computer means compares the length increment of the film between said spaced marker by said sensing means, and a predetermined command value of impulses.

4. The apparatus of claim 2, wherein said control means includes a clock or computer providing a sequence of pulses; pulse-controlled motor means coupled to and forming part of said continuous film feeding means; pulse-controlled cross sealing motor means coupled to and operation the cross-sealing means; and pulse-controlled sealing drive motor means; and wherein said control means is connected to all said motor means, and respectively, controls the pulse rates of pulses applied to the respective motor means as a function of comparison of the senred spacing of markers or number of counts or impulses with said command reference.

5. The apparatus of claim 2, wherein the welding stroke in vertical direction of the sealing jaws upon engagement with the film is shorter than the vertical length of a bag.

6. A form-fill-seal packaging apparatus substantially as herein described with reference tothe accompanying drawings. DATED this 21st day of December, 1989. ILAPAK RESEARCH DEVELOPMENT S.A. Attorney: WILLIAM S. LLOYD Fellow Institute of Patent Attorneys of Australia *of SHELSTON WATERS T 0 nt$N 1 j I