Continuous motion drive mechanism for a form, fill, and seal machine

Abstract

The present invention provides a drive mechanism for a form, fill and seal machine for forming a tube out of a heat sealable sheet. The machine includes front and rear jaw assemblies arranged on opposite sides of the tube, which follow the movement of the tube during the sealing operation. The drive mechanism for each side of the jaw assemblies comprises a front drive gear and a real drive gear, which are driven in opposing directions. The front and rear drive gears are coupled to front and rear linkage bases, respectively, which in turn are coupled to the front and rear jaw assemblies, respectively, to cyclically bring the opposing jaw assemblies into contact to seal the tube. A slide bar may be disposed directly between the front and rear linkage bases, or alternatively, directly between the front and rear jaw assemblies, to help maintain the linkage bases and jaw assemblies in registry during their rotational cycles, thereby improving the sealing quality of the package being formed.

Description

TECHNICAL FIELD

The present invention relates to a packaging apparatus and a method of forming packages. More specifically, the invention relates to a vertical form, fill and seal machine in which the film material is fed downwardly and cross-sealing jaws move downwardly during the sealing operation and are synchronized with the film and the package being formed.

BACKGROUND INFORMATION

Machines for forming, filling and sealing packages from a continuous film are widely used in the packaging industry. Basic form, fill and seal (FFS) machines can be adapted to form packages of different shapes and sizes. A conventional machine may utilize a supply of packaging film, which is drawn over a forming means to achieve a tubular shape. The tubular film then may be sealed vertically using, a seam sealing machine. The contents are inserted into the package and the package may be closed using a sealing mechanism designed to seal upper and lower regions of the package. The filled and sealed package then is cut from the film roll.

The cross-sealing mechanism, which seals the top and bottom of each package, is a critical component of the FFS machine insofar as controlling the quality of the package. Various designs have been proposed for a cross-sealing mechanism, but many of the designs have drawbacks. For example, known cross-sealing mechanisms may not operate at a precise time in the package cycle, thereby yielding a reduced quality seal.

Further, many current cross-sealing mechanisms are complex and require significant monitoring and adjustment to assure the quality of the finished product. An intermittent or discontinuous movement of the Film and the tubular package formed therefrom introduces problems in maintaining control over the film and complicates the film feeding mechanism. For at least these reasons, there is a need for a cross-sealing mechanism that performs the sealing and cutting operations while moving vertically in time with the vertical movement of the package being formed.

One particular FFS machine in which the cross-sealing jaws move downwardly during the sealing operation is disclosed in U.S. Pat. No. 5.752,370 to Linkiewicz (“the '370 patent”), assigned to Triangle Package Machinery, Inc., the same assignee as for the present application. In the '370 patent, a drive mechanism for forming a tube out of a heat sealable sheet is disclosed. The FFS machine comprises first and second cyclically movable jaw assemblies arranged on opposite sides of the tube, which follow the movement of the tube during the sealing operation.

In the '370 patent, the drive mechanism for each side of the jaw assemblies comprises five gears, i.e., ten gears total are employed. On each side, a driver gear meshes with and drives an upper rear drive gear and a lower rear drive gear in counterclockwise directions. The upper rear drive gear and lower rear drive gear mesh with and drive an upper front drive gear and a lower front drive gear, respectively, in clockwise directions. The upper and lower rear drive gears are coupled to a rear linkage base, which in turn is coupled to the rear sealing jaw using two parallel links. This mechanism causes the rear sealing jaw to move in a counterclockwise direction. Similarly, the upper and lower front drive gears are coupled to the front sealing jaw, which rotates in a clockwise direction. As the tube is fed downwardly, the front and rear sealing jaws engage the tube for a portion of their cycle to seal the tube. A plurality of pressure devices, such as rubber torsion mounts, may be employed to bias the pair of cyclically movable jaw assemblies toward each other in arcuate paths to yield an improved seal.

Despite the advantages of the design in the '370 patent, there is a need for an improved FFS machine that is cost-effective, utilizes fewer components, is easy to maintain and service, and still provides high quality sealing capabilities in the finished product.

SUMMARY

The present invention provides a drive mechanism for a FFS machine for forming a tube Out of a heat sealable sheet. The FFS machine includes front and rear jaw assemblies arranged on opposite sides of the tube, which follow the movement of the tube during the sealing operation. The drive mechanism for each side of the jaw assemblies comprises a front drive gear and a rear drive gear, which are driven in opposing directions.

A front linkage base is operably coupled between the front drive gear and the front jaw assembly to rotate the front jaw assembly in the same direction as the front drive gear. Similarly, a rear linkage base is operably coupled between the rear drive gear and the rear jaw assembly to rotate the rear jaw assembly in the same direction as the rear drive gear. In effect, the front and rear sealing jaws are cyclically rotated in opposing directions and engage a tube in synchronous fashion to seal the tube.

In a preferred embodiment, four parallel links, each having upper and lower regions, are employed to couple the linkage bases to the jaw assemblies. Specifically, the lower regions of first and second parallel links are coupled to the front linkage base, while their upper regions are operably coupled to the front jaw assembly. Similarly, the lower regions of third and fourth parallel links are coupled to the rear linkage base, while their upper regions are operably coupled to the rear jaw assembly. The parallel links may employ mount members having pressure devices, which function to bias the front and rear jaw assemblies towards engagement, thereby enhancing the sealing capabilities of the FFS machine.

In a first embodiment, a slide bar is disposed between the front linkage base and the rear linkage base to keep these linkage bases in registry with one another, thereby improving the sealing quality of the package being formed. The front and rear linkage bases may be attached to front and rear linkage housings, each having bores disposed therethrough. The slide bar extends longitudinally through the bores of the front and real linkage housings to guide the linkage bases.

In an alternative embodiment, the slide bar is disposed directly between the front and rear jaw assemblies to keep the jaw assemblies in registry. The front and rear jaw assemblies preferably comprise bores disposed therethrough. The slide bar extends longitudinally through the bores to maintain the sealing jaws in registry throughout their rotational cycle. During the cycle, the slide bar may move vertically along a vertical rod, as necessary.

Other systems, methods, features and advantages of the invention will be, or will become, apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be within the scope of the invention, and be encompassed by the following claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be better understood with reference to tile following drawings and description. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like referenced numerals designate corresponding parts throughout the different views.

FIG. 1 is a left side schematic view of a sealing jaw mechanism provided in accordance with a first embodiment.

FIG. 2 is a schematic view that illustrates movement of a sealing jaw during a rotational cycle.

FIG. 3 is a perspective view of the sealing jaw mechanism of FIG. 1 as shown from the front upper right.

FIG. 4 is a top view of the sealing jaw mechanism of FIG. 3.

FIG. 5 is a front end view of the sealing jaw mechanism of FIG. 3.

FIG. 6 is a perspective view of an alternative sealing jaw mechanism as shown from the front upper right.

FIG. 7 is a top view of the sealing jaw mechanism of FIG. 6.

FIG. 8 is a front end view of the sealing jaw mechanism of FIG. 6.

FIG. 9 is a perspective view of the sealing jaw mechanism of FIG. 6 as shown from the front upper left.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention relates generally to a drive mechanism for a FFS machine. The FFS machine utilizes transverse sealing jaws to form sealed bags from a continuous film of packaging material. During operation, vacuum belts engage the packaging material and pull it off a mandrel. The film is fed to a seam sealing station and is sealed longitudinally by a stationary seam sealer. The film is thereby formed into a tube, which is next fed to a transverse sealing station. The transverse sealing station comprises a sealing jaw mechanism, which is described in greater detail below.

Generally speaking, the sealing jaw mechanism seals the upper and lower surfaces of the package to be formed. The sealing jaw mechanism comprises front and rear jaw assemblies arranged on opposite sides of the tube, which follow the movement of the tube during the sealing operation. As the tube is fed vertically through the sealing jaws, the front and rear jaws are rotated together in synchronous motion and come into contact for a portion of their cycle to seal the tube.

Referring now to FIGS. 1-5, a first embodiment of a drive mechanism for a FFS machine is shown. Sealing jaw mechanism 120 comprises left gear case 122 and right gear case 124, as shown in FIG. 3. Left gear case 122 includes driver gear 160, which is carried by input shaft 126 (see FIG. 1). Input shaft 126 is coupled to servo motor 132 by gear box 130, as shown in FIG. 3. The speed of driver gear 160 is identical to the speed of a driver gear (not shown) housed in right gear case 124 and coupled to servo motor 132 by input shaft 128. Therefore, as will be explained in greater detail below, the left and right portions of the drive assembly of sealing jaw mechanism 120 are synchronized.

It should be noted that left gear case 122 and right gear case 124, along with their respective components that are coupled to front and rear sealing jaws 140 and 150, are mirror images of each other. For this reason, reference will be made to FIGS. 1-5 for a detailed discussion of the drive from left gear case 122 to the various components on the left half of assembly 120 that are coupled to front and rear sealing jaws 140 and 150.

In FIG. 1, a schematic of the operation of sealing jaw mechanism 120 is shown. Driver gear 160 of left gear case 122 rotates in a clockwise direction. Driver gear 160 meshes with and drives rear drive gear 162 in a counterclockwise direction. Front drive gear 161 meshes with rear drive gear 162, and therefore front drive gear 161 is driven in a clockwise direction, as depicted in FIG. 1. Ultimately, as will be explained in greater detail below, the rotation of front drive gear 161 and rear drive gear 162 causes front sealing jaw assembly 142 to rotate in a clockwise direction and causes rear sealing jaw assembly 152 to rotate in a counterclockwise direction, thereby providing the sealing functionality of the FFS machine.

Front drive gear 161 is operably coupled to front linkage base 155 and causes rotation of front linkage base 155 in a clockwise direction. In a preferred embodiment, front drive gear 161 is attached to output shaft 171, which is coupled to crank arm 176a, which in turn is coupled to front linkage base 155 at pivot shaft 178a, as shown in FIG. 1.

Similarly, rear drive gear 162 is attached to Output shaft 172, which is coupled to crank arm 176b, which in turn is coupled to rear linkage base 156 at pivot shaft 178b. Therefore, rear drive gear 162 causes counter-clockwise rotation of rear linkage base 156.

Sealing jaw mechanism 120 preferably further comprises parallel links 181, 182, 183 and 184. First and second parallel links 181 and 182 couple front linkage base 155 to front jaw assembly 142, while third and fourth parallel links 183 and 184 couple rear linkage base 156 to rear jaw assembly 152, as depicted in FIG. 1. Specifically, the lower ends of first and second parallel links 181 and 182 are coupled to front linkage base 155 by mount members 191a and 192a, respectively, as shown in FIG. 1. Similarly, the lower ends of third and fourth parallel links 183 and 184 are coupled to rear linkage base 156 by mount member 193a and 194a, respectively.

The upper ends of first and second parallel links 181 and 182 are coupled to front jaw assembly 142, which carries front sealing jaw 140, by mount members 191b and 192b, respectively, as shown in FIG. 1. Similarly, the upper ends of third and fourth parallel links 183 and 183 are coupled to rear-jaw assembly 152, which carries rear sealing jaw 150, by mount members 193b and 194b, respectively.

The mount members used to couple both the upper and lower ends of parallel links 181-184 preferably have circular openings formed therein, within which pressure devices are mounted. More preferably, the pressure devices may include a plurality of elastic members or rubber torsion mounts 523, as explained with reference to FIGS. 29-30 of the '370 patent, which is hereby incorporated by reference in its entirety. Such pressure devices function to bias the front and rear jaw assemblies toward each other in arcuate paths. If employed, the sealing time in which front sealing jaw 140 engages rear sealing jaw 150 may be increased.

In the embodiment of FIGS. 1-5, left slide bar 135 is used to maintain the orientation of front linkage base 155 with rear linkage base 156. Similarly, right slide bar 136 is employed to maintain the orientation of symmetrical linkage bases driven through right gear case 124, as shown in FIGS. 4-5.

In a preferred embodiment, the upper end of front linkage base 155 is attached to front linkage housing 185, while the upper end of rear linkage base 156 is attached to rear linkage housing 186, as best shown in FIGS. 1, 3 and 5. Front and rear linkage housings 185 and 186 may be separate components that are welded to upper surfaces of front and rear linkage bases 155 and 156, respectively, or alternatively, may be integrally formed with the linkage bases during manufacture.

Front and rear linkage housings 185 and 186 each comprise a bore formed longitudinally therethrough. At least one bushing 195 preferably is disposed partially or fully within the bores, as shown in FIGS. 3 and 5. Left slide bar 135 preferably comprises an outer diameter that is slightly smaller than an inner diameter provided by bushings 195, thereby permitting front and rear linkage housings 185 and 186 to slide longitudinally over left slide bar 135.

Specifically, as front linkage base 155 and rear linkage base 156 are driven in clockwise and counterclockwise directions, respectively, front and rear linkage housings 185 and 186 may slide longitudinally over left slide bar 135, which may move vertically with the rotating components. Since left and right slide bars 135 and 136 maintain the front and rear linkage bases in registry, symmetrical rotation and front and rear sealing jaw assemblies 142 and 152 may be achieved.

It should be noted that, in the schematic of FIG. 1, the initial contact of front and rear sealing jaws 140 and 150 is depicted, while in the illustrations of FIGS. 3-5, front and rear sealing jaws 140 and 150 are not engaged.

The rotational motion of rear sealing jaws 150 is depicted in FIG. 2. During a cycle, initial contact between front and rear sealing jaws 140 and 150 occurs at point 146, which is about 54 degrees above horizontal, as shown in FIG. 2. Rear sealing jaw 150 moves vertically downwardly along cord 147 after initial contact with front sealing jaw 140 to point 148, which is about 54 degrees below horizontal. At point 148, rear sealing jaw 150 intersects the circular arc that it normally follows. As a result, front and rear sealing jaws 140 and 150 travel vertically downwardly for a total arc of about 108 degrees, which is about 30% of the total mechanical cycle.

Initial engagement of front and rear sealing jaws 140 and 150 commences as both sealing jaws are moving downwardly. If pressure devices Such as rubber torsion mounts are employed, as noted above, it may ensure that the sealing jaws remain engaged under pressure and move vertically downwardly during the entire sealing phase.

As will be apparent, the speed of servo motor 132 is set by a microprocessor controller during the sealing phase such that the downward movement of front and rear sealing jaws 140 and 150 is synchronized with the downward movement of the tubular container being formed. In operation, after the film is sealed longitudinally by the stationary seam sealer and formed into a tube, the tube is fed vertically through front and real sealing jaws 140 and 150. When front and rear sealing jaws 140 and 150 are brought into engagement for a portion of their cycle, the upper and lower surfaces of the package are sealed. A cutting knife (not shown) may be employed to cut the tipper and lower Surfaces of the package.

It will be appreciated that while four parallel links 181-184 are depicted in the embodiment of FIGS. 1-5, fewer links may be employed. For example, a first parallel link may be used to couple front linkage base 155 to front jaw assembly 142, while a second parallel link may be used to couple rear linkage base 156 to rear jaw assembly 152. If only one parallel link is employed for each linkage base, then the parallel links may be thicker or comprise a different configuration than shown in FIGS. 1-5. Alternatively, parallel links 181-184 may be omitted entirely and front and rear linkage bases 155 and 156 may be coupled directly to front and rear jaw assemblies 142 and 152, respectively.

Referring no to FIGS. 6-9, an alternative embodiment is described. In FIGS. 6-9, alternative sealing jaw mechanism 220 is similar to sealing jaw mechanism 120 of FIGS. 1-5, but comprises a different drive mechanism, as explained below.

Like the embodiment above, it should be noted that the components on the left half of sealing jaw mechanism 220, which are coupled to front and rear sealing jaws 240 and 250, are mirror images of the components on the right half of mechanism 220. Therefore, reference will only be made in FIGS. 6-9 to a detailed discussion of the various components on the left half of sealing jaw mechanism 220.

In FIG. 6, output shafts 271 and 272 are driven by front drive gear 261 and rear drive gear 262, respectively (see FIG. 9). Output shafts 271 and 272 are coupled to crank arms 276a and 276b, respectively. Crank arms 276a and 276b are coupled to front and rear linkage bases 255 and 256, respectively, at pivot shafts. In effect, clockwise rotation of front drive gear 261 causes clockwise rotation of front linkage base 255 through the output shaft and the crank arm. Similarly, counterclockwise rotation of rear drive gear 262 causes counterclockwise rotation of rear linkage base 256.

In a preferred embodiment, first and second parallel links 281 and 282 interconnect front linkage base 255 with front jaw assembly 242, while third and fourth parallel links 283 and 284 interconnect rear linkage base 256 with rear jaw assembly 252, as explained above with respect to the embodiment of FIGS. 1-5. Preferably, the upper and lower regions of parallel links 281-284 employ mount members, which may comprise pressure devices that function to bias the pair of jaw assemblies toward each other in arcuate paths.

In the embodiment of FIGS. 6-9. Left slide bar 235 is coupled directly between front jaw assembly 242 and rear jaw assembly 252. Preferably, left slide bar 235 comprises an outer diameter that is slightly smaller than an inner diameter of bores formed in front and rear jaw assemblies 242 and 252, as depicted in FIGS. 6-9, thereby permitting the jaw assemblies to slide longitudinally over left slide bar 235. Similarly, right slide bar 236 is employed so that the mirror-image components on the right side of front and rear jaw assemblies 242 and 252 may slide over right slide bar 236.

As shown in FIG. 9, left slide bar 235 is coupled to left vertical rod 265 by slidable bracket 267. Left slide bar 235 is attached to a front portion of slidable bracket 267. A rear portion of slidable bracket 267 comprises a bore formed therein. Left vertical rod 265 is disposed through the bore formed in slidable bracket 267 to permit the bracket to slide vertically along the rod. Left vertical rod 265 is attached to rigid frame 269, as shown in FIG. 9. Similarly, right vertical rod 266 is employed so that right slide bar 236 may move vertically over vertical rod 266 via slidable bracket 268.

In operation, as front sealing jaw 240 and rear sealing jaw 250 rotate clockwise and counterclockwise, respectively, front and rear jaw assemblies 242 and 252 slide longitudinally over left slide bar 235 and right slide bar 236 to maintain the sealing jaws in registry throughout their rotational cycle. During the cycle, slidable bracket 267 may move vertically along left vertical rod 265, while slidable bracket 268 may move vertically along right vertical rod 266, as necessary. It should be noted that the orientation of front and rear linkage bases 255 and 256 are maintained by the slide bars acting through front and rear jaw assemblies 242 and 252 and parallel links 281-284.

The bores formed in front and rear jaw assemblies 242 and 252 may comprise bushings 295, as depicted in FIGS. 6-7 and described above, or another type of guide means for facilitating longitudinal movement of the jaw assemblies along the slide bars.

It will be apparent that in the embodiment of FIGS. 6-9, fewer links may be employed. For example, as noted above with respect to the embodiment of FIGS. 1-5, only one parallel link may be used to couple each linkage base to its respective jaw assembly, or alternatively, each linkage base may be coupled directly to a front or rear portion of the jaw assembly.

While various embodiments of the invention have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the invention. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents.

Claims

1. A drive mechanism for a form, fill and seal machine for forming a tube out of a heat sealable sheet, of the type including first and second jaw assemblies arranged on opposite sides of the tube that follow the movement of the tube during the sealing operation, wherein the drive mechanism for each side of the jaw assemblies comprises:

a first sealing jaw mechanism having a first jaw assembly, a first drive gear and a first linkage base, wherein the first linkage base is adapted to be coupled between the first drive gear and the first jaw assembly;

a second sealing jaw mechanism having a second jaw assembly, a second drive gear and a second linkage base, wherein the second linkage base is adapted to be coupled between the second drive gear and the second jaw assembly; and

at least one slide bar adapted to be disposed between the first and second sealing jaw mechanisms to keep the jaw mechanisms in registry.

2. The drive mechanism of claim 1 wherein the slide bar is adapted to be disposed between the first jaw assembly and the second jaw assembly.

3. The drive mechanism of claim 1 wherein the slide bar is adapted to be disposed between the first linkage base and the second linkage base.

4. The drive mechanism of claim 1 further comprising:

a first linkage housing having a bore disposed therein; and

a second linkage housing having a bore disposed therein,

wherein the slide bar extends longitudinally through the bores of the first linkage housing and the second linkage housing.

5. The drive mechanism of claim 4 further comprising at least one bushing disposed in the first and second linkage housings, wherein the slide bar extends longitudinally through the bushings.

6. The drive mechanism of claim 1 further comprising:

a first output shaft driven by the first drive gear;

a crank arm operably coupled between the first output shaft and the first linkage base, wherein rotation of the crank arm effects rotation of the first linkage base in the same direction as the first drive gear;

a second output shaft driven by the second drive gear; and

a crank arm operably coupled between the second output shaft and the second linkage base, wherein rotation of the crank arm effects rotation of the second linkage base in the same direction as the second drive gear.

7. The drive mechanism of claim 1 further comprising:

a first parallel link having upper and lower regions; and

a second parallel link having upper and lower regions,

wherein the lower regions of the first and second parallel links are operably coupled to the first linkage base, and the upper regions of the first and second parallel links are operably coupled to the first jaw assembly.

8. The drive mechanism of claim 7 further comprising:

a third parallel link having upper and lower regions; and

a fourth parallel link having upper and lower regions,

wherein the lower regions of the third and fourth parallel links are operably coupled to the second linkage base, and the upper regions of the third and fourth parallel links are operably coupled to the second jaw assembly.

9. A drive mechanism for a form, fill and seal machine for forming a tube out of a heat sealable sheet, of the type including first and second jaw assemblies arranged on opposite sides of the tube that follow the movement of the tube during the sealing operation, wherein the drive mechanism for each side of the jaw assemblies comprises:

the first and the second jaw assemblies;

a first drive gear rotatable in a first driven direction and a second drive gear rotatable in a second driven direction opposite the first driven direction;

a first linkage base operably coupled between the first drive gear and the first jaw assembly;

a second linkage base operably coupled between the second drive gear and the second jaw assembly; and

at least one slide bar adapted to be disposed between the first and second jaw assemblies.

10. The drive mechanism of claim 9 wherein the first and second jaw assemblies each comprise bores formed therein, the slide bar being longitudinally disposed through the bores in the first and second jaw assemblies.

11. The drive mechanism of claim 10 further comprising at least one bushing disposed in the bores of the first and second jaw assemblies, wherein the slide bar extends longitudinally through the bushings.

12. The drive mechanism of claim 9 further comprising:

a vertical rod; and

a slidable bracket attached to a portion of the slide bar, wherein the slidable bracket is disposed for vertical movement along the vertical rod.

13. The drive mechanism of claim 9 further comprising:

a gear case located on one side of the tube;

an input drive shaft for the gear case; and

a driver gear journaled inthe gear case and carried by the input drive shaft, wherein the driver gear drives rotation of the second drive gear, which in turn drives rotation of the first drive gear.

14. The drive mechanism of claim 9 further comprising:

a first output shaft driven by the first drive gear;

a crank arm operably coupled between the first output shaft and the first linkage base, wherein rotation of the crank arm effects rotation of the first linkage base in the same direction as the first drive gear;

a second output shaft driven by the second drive gear; and

a crank arm operably coupled between the second output shaft and the second linkage base, wherein rotation of the crank arm effects rotation of the second linkage base in the same direction as the second drive gear.

15. The drive mechanism of claim 9 further comprising:

a first parallel link having upper and lower regions; and

a second parallel link having upper and lower regions,

wherein the lower regions of the first and second parallel links are operably coupled to the first linkage base, and the upper regions of the first and second parallel links are operably coupled to the first jaw assembly.

16. The drive mechanism of claim 15 further comprising:

a third parallel link having upper and lower regions; and

a fourth parallel link having upper and lower regions,

wherein the lower regions of the third and fourth parallel links are operably coupled to the second linkage base, and the upper regions of the third and fourth parallel links are operably coupled to the second jaw assembly.

17-23. (canceled)