Packaging machine for block bottom bags

Abstract

A rotary packaging machine (10) that receives tubular bag material and moves the tubular bag material in a direction (11). Product is delivered to the interior of the tubular bag material with the bag material then being sealed and cut to form bags of the product. The machine (10) has a jaw carriage (14) that is reciprocated while the jaws (29) are rotated.

Description

TECHNICAL FIELD

The present invention relates to packaging machines that form bags and more particularly but not exclusively to packaging machines that form bags to contain a product such as a food product.

BACKGROUND OF THE INVENTION

Packaging machines receive a strip of bag forming material and pass the material about a former so that the bag material assumes a tubular configuration. The material is longitudinally sealed, and product delivered to the interior of the tubular bag material through the former. The sealing jaws then engage the tubular bag material to transversely seal and cut the bag material so as to produce bags containing the product.

Described in U.S. Pat. No. 4,663,917 is a packaging machine that can form bags as discussed above. The particular machine of this USA patent has sealing jaws that are rotatably driven through repeated revolutions in opposite angular directions. Operatively associated with the sealing jaws are stripper bars and closer bars that strip the tubular bag material and close the tubular bag material to aid the jaws in forming the bags. The stripper bars move down the tubular bag material to aid in reducing the volume occupied by the product. The closer bars engage the tubular bag material above the stripper bars so as to provide a length of tubular bag material that is engaged by the jaws. This length of tubular bag material, by cooperation of the stripper bars and closer bars is free of any product thereby ensuring a good seal. The sealing jaws have a blade that transversely cuts the tubular bag material so as to form the bags.

The above discussed machines typically form bags that taper in depth at each end.

It is desirable with some products to produce bags that have a “block bottom”. That is a bag that has a longitudinal end formed so that the bag can stand on that longitudinal end on a shelf. These bags are not formed by a rotary machine as described in the abovementioned USA patent. These are formed by vertically reciprocating machines in which the jaws are reciprocated vertically along a linear path, and also reciprocated horizontally along a linear path, with the jaws approaching each other and engaging the tubular bag material to form the bag ends. To form a “block bottom” bag movement of the tubular bag material through the machine is haltered. These machines that are adapted to form block bottom bags have a number disadvantages including low production rates and complexity of the machinery since the jaws must be vertically and horizontally reciprocated. This horizontal and vertical reciprocation also makes the machines vulnerable to failure due to the accelerations imposed on the various components.

OBJECT OF THE INVENTION

It is the object of the present invention to overcome or substantially ameliorate at least one of the above disadvantages.

SUMMARY OF THE INVENTION

There is disclosed herein a packaging machine to form bags, containing a product, from tubular bag material into which the product is delivered, the tubular bag material being moved relative to the machine in a predetermined direction, said machine including:

a base;

a jaw carriage supported on the base for reciprocating movement generally parallel to said direction;

a pair of jaws mounted on the carriage and moved in unison to engage the tubular bag material to transversely seal the tubular bag material to form bags;

a pair of generally parallel shafts, each shaft being operatively associated with a respective one of the jaws to drive the jaws, the shafts having longitudinally axes that extend generally transverse of said direction;

a jaw drive assembly operatively associated with the shafts to drive the shafts through repeated revolutions in opposite angular directions so that the jaws engage the tubular bag material;

a carriage drive assembly operatively associated with the carriage to cause said reciprocating movement; and

a controller operatively associated with the drive assemblies to coordinate the assemblies.

Preferably, said machine includes a pair of cooperating stripper bars, each stripper bar being operatively associated with a respective one of the jaws to move therewith to strip the tubular bag material.

Preferably, said machine includes a pair of tube closer bars, each of the closer bars being operatively associated with a respective one of the jaws to engage the tubular bag material to close the tubular bag material.

Preferably, said jaw drive assembly is mounted on said carriage.

Preferably, said carriage drive assembly is a linear motor at least partly mounted on said base and at least partly mounted on said carriage, so that said carriage when reciprocated moves along a generally linear path.

Preferably, each jaw is attached to its respective shaft by a jaw support.

Preferably, each jaw support includes at least one arm extending generally radially relative to its respective shaft.

Preferably, each jaw is fixed relative to its respective support.

In an alternative preferred form, each jaw is attached to its respective shaft by a support, with each jaw being mounted on its respective support for angular movement relative thereto about an axis generally transverse of said direction.

Preferably, the jaws are attached by guides so that the jaws move in unison in opposite directions while facing each other.

Preferably, the jaws are mounted on their respective supports for movement relative thereto in a radial direction.

Preferably, said carriage includes a pair of generally parallel walls between which said shafts extend, and an end wall adjacent said base and including portion of said linear motor.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred forms of the present invention will now be described by way of example with reference to the accompanying drawings wherein:

FIG. 1 is a schematic isometric view of a packaging machine;

FIG. 2 is a schematic isometric view of the packaging machine of FIG. 1;

FIG. 3 is a schematic isometric view of a bottom isometric view of the packaging machine of FIGS. 1 and 2;

FIG. 4 is a schematic side elevation of the jaw mechanism of the packaging machine of FIG. 1;

FIG. 5 is a schematic end elevation of the jaw assembly of FIG. 4, with the jaws in various positions;

FIG. 6 is a schematic side elevation of the jaws of FIG. 5;

FIG. 7 is a schematic end elevation of an alternative jaw assembly to that of FIGS. 4 to 6;

FIG. 8 is a schematic side elevation of the jaw assembly of FIG. 7; and

FIG. 9 is a further schematic side elevation of the jaw assembly of FIG. 7, with the jaws in various positions.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIGS. 1 to 6 of the accompanying drawings there is schematically depicted a rotary packaging machine 10. The machine 10 would receive tubular bag material moving in the direction 11. The tubular bag material would be configured by a former (not illustrated). Product is delivered into the interior of the tubular bag material, and then delivered to the machine 10 to form bags. Typically the machine 10 would also have a film drive assembly that moves the tubular bag material through the machine 10. Typical film drive units are disclosed in U.S. Pat. No. 4,910,943 and U.S. patent application Ser. No. 11/178150 (lodged on 8 Jul. 2005). An example of a former assembly is described in U.S. Pat. No. 7,152,387.

The machine 10 has a base 12 providing a wall 13 that is generally vertically oriented. Mounted for vertical reciprocating movement adjacent the wall 13 is a jaw is carriage 14. The jaw carriage 14 it reciprocates in the direction 15, that is a direction generally parallel to the direction 11. In this embodiment the direction 15 is generally vertical.

The carriage 15 includes a pair of side walls 16 that are generally parallel and coextensive and spaced transversely of the direction 15. The side walls 16 are fixed to and supported by an end wall 17, the end wall 17 being generally vertically oriented and located adjacent the wall 13.

Mounted on the wall 13 and end wall 17 is a carriage drive assembly 18, the drive assembly 18 being an electric linear motor 19 including tracks 20. The tracks 20 are fixed to the wall 13 and engage bearings 21 fixed to the end wall 17. The tracks 20 and bearings 21 restrain the carriage 14 to reciprocate in the direction 15. Upon electric power being delivered to the motor 19, the carriage 14 is caused to reciprocate in a controlled manner. The carriage 14 has vertical limits in respect of its movement, at which limits limit switches or stops 21 are engaged. In this embodiment, as an example, attached to the wall 13 would be the “stator” of the motor 19, while attached to the wall 17 is the “rotor” 24. In this embodiment the motor 19 could be a “stepper” or “servo” motor or an induction motor.

Mounted in the carriage 14 is a jaw assembly 20. The jaw assembly 20 could typically be the jaw assembly described in U.S. Pat. No. 4,663,917 (European Patent 0165819).

The jaw assembly 20 includes a pair of shafts 25 that are rotatably supported in bearings mounted in the walls 16. Accordingly the shafts 25 extend generally transverse of the direction 11, and therefore in this embodiment extends generally horizontal. As the shafts 25 are generally parallel, the shafts have generally parallel longitudinal axes 26 that are also generally horizontally oriented. Fixed to each of the shafts 25 is a jaw support 27, which in this embodiment is an arm 28 that extends radially from its respective shaft 25. At the radially outer end of each arm 28 is a sealing jaw 29 that would typically incorporate a blade to cut the bags from the tubular bag material. The sealing jaws 29 heat the tubular bag material to form the transverse seals in the tubular bag material. As best seen in FIGS. 4 to 6, the shafts 25 are illustrated in three positions, A, B and C. As can be seen from the drawings, the shafts 25 reciprocate vertically as they are mounted in the carriage 14. The arms 28 are rotated in synchronism in opposite rotational directions 30 and 31, and are rotated through repeated revolutions in their respective directions.

As is best seen in FIGS. 4 and 5, in this embodiment the jaw assembly 22 is includes a pair of stripper bars 32 with which there is associated bag shields 33. The bars 32 and shields 33 are supported by pairs of levers 34, while tube closer bars 34 are supported by pairs of levers 36. This arrangement is disclosed in U.S. Pat. No. 7,159,376 (European Patent 72258450.2). The levers 34 and 36 are pivotally mounted on a bracket 43 fixed to a respective one of the shafts 25. As the arms 28 rotate about their respective axis 26, each jaw 29, relative to the carriage 14, follows a circular path about the respective axis 26. As the levers 34 and 36 are attached to the arms 28, the stripper bars 32 and closer bars 35 follow predetermined paths at least partly defined by the cam surfaces 37 and 38.

In FIG. 4, the arms 28 are illustrated being rotated with the carriage 14 being maintained stationary. Accordingly the motor 23 has been activated to retain the carriage 14 stationary at a desired position relative to the base 12. As the arms 28 rotate the stripper bars 32 engage the tubular bag material and move down the tubular bag material to move the product towards the previously formed seal. Thereafter the tube closer bars 35 engage the tubular bag material and prevent further product passing down the tubular bag material towards the stripper bars 32.

The stripper bars 32 and closer bars 35 separate so as to provide a strip of tubular bag material that is engaged by the sealing jaws 29 to form the transverse seal and to cut the formed bag from the tubular bag material. This arrangement with the carriage 14 generally stationary, produces a bag of reasonably conventional shape that is not necessarily a “block bottom” bag.

When the carriage 14 is vertically reciprocated at predetermined speeds, the jaw assembly 22 behaves as illustrated in FIGS. 5 and 6. In FIGS. 5 and 6 the shafts 25 are illustrated in three positions A, B and C. As is most easily seen in FIG. 6, as the arms 28 rotate in their respective directions 30 and 31, in combination with the vertical movement of the carriage 14, the jaws 22 can move along a desired path. Purely as an example, the jaws 29 could be moved along a linear path 39 by the appropriate positioning of the carriage 14, as well as the velocity of the carriage 14 and the acceleration of the carriage 14, in combination with rotational speed of the shaft 25.

It should be appreciated that the path 39 may be varied from a linear path again by proper coordination of the carriage 14 and the shafts 25. By having the carriage 14 moving vertically upward, as the jaws 29 approach, the bags being formed have an appropriate end seal area so that the bags have a “block bottom”. As best seen in FIG. 3, the machine 10 includes a jaw drive assembly 40 including an electric motor 41 that may be an induction stepper or servo motor. The motor 41 drives gears 42, which each of the gears 42 being drivingly connected to a respective one of the shafts 25 so that the shafts 25 are rotably driven through repeated revolutions in opposite directions.

The stripper bars 32 and closer bars 35 (as best seen in FIG. 5), can be moved along an appropriate path, such as a linear path by co-ordination of the drive assembly 18 and drive assembly 40. In this specific example, the path is a linear path approaching the tubular bag material.

The carriage drive assembly 18 and jaw drive assembly 40 are electrically connected to a controller 43 (incorporating a computer) that delivers electric power to and controls the operation and coordination of the motors 19 and 41 so that a desired bag configuration is produced. In this respect it should be appreciated the carriage 14 can be selectively maintained stationary or can be reciprocated at a desired rate, and the shafts 25 rotated at the desired rate to provide bags of desired configuration.

In FIGS. 7 to 9, there is schematically depicted a jaw assembly 50 that is a modification of the assembly 22. In this embodiment, again the shafts 25 are employed. However pivotally attached to the shafts 25 by means of supports 51 are jaw devices 52. The devices 52 each include a jaw base 54 pivotally attached to a support 51 by a pivot 53, so that each jaw base 54 is pivotally mounted on its associated shaft 25. As its shafts 25 rotate, the jaw bases 54 follow a circular path about their respective shafts 25, however their orientation remains unchanged since the jaw bases are linked by one or more bars 58 that are slidably associated with the jaw bases 54. Each bar 58 extends between the jaw bases 54. Accordingly as each shaft 25 rotates, each jaw base 54 rotates about its respective pivot 53.

Each jaw base 54 has a jaw 55 as well as a stripper 56 and a closer bar 57. The bars 56 and 57 are slidably located in their respective bases 54 so that they are movable between an extended position (as shown in FIG. 7) and a partly retracted position as shown in FIGS. 8 and 9.

As each shaft 25 is rotated through repeated revolutions in their respective direction 30 or 31, the bars 56 engage the tubular bag material to strip the bag material, while the bars 57 close the bag material to thereby provide an area that is engaged by the sealing jaws 55.

In FIG. 8 there is schematically depicted the assembly 50 in operation with the carriage 14 stationary. Accordingly the bases 54 follow a circular path. However in FIG. 9 there is schematically depicted the assembly 50 of FIG. 7, with the carriage 14 being reciprocated to vertically move the shafts 25 so that “block bottom” bags are is formed. The jaws 54 are shown in three positions, A, B and C. As can be seen in FIG. 9, movement of the carriage 14 can be governed and coordinated with rotation of the shafts 25 so that the jaws 55 move along a generally linear path when stripping and closing the tubular bag material and generally up until when the jaws 55 engage the tubular bag material to form a seal and separate the bag being formed.

In the above described preferred embodiments, when the carriage 14 is stationary, the jaws 29 or 55 follow generally circular paths relative to the base 12. However when “block bottom” bags are to be formed, the carriage 14 is reciprocated vertically in a coordinated manner with the rotation of the shafts 25, so that the jaws move along a linear path or a slightly curved path when approaching the tubular bag material to strip and seal the tubular bag material. The path along which the jaws 29 and 55 pass is determined by the controller 43 that is “programmed” by an operator.

Claims

1. A packaging machine to form bags, containing a product, from tubular bag material into which the product is delivered, the tubular bag material being moved relative to the machine in a predetermined direction, said machine including: a base;a jaw carriage supported on the base for reciprocating movement generally parallel to said direction;a pair of jaws mounted on the carriage and moved in unison to engage the tubular bag material to transversely seal the tubular bag material to form bags;a pair of generally parallel shafts, each shaft being operatively associated with a respective one of the jaws to drive the jaws, the shafts having longitudinally axes that extend generally transverse of said direction;a jaw drive assembly operatively associated with the shafts to drive the shafts through repeated revolutions in opposite angular directions so that the jaws engage the tubular bag material;a carriage drive assembly operatively associated with the carriage to cause said reciprocating movement; anda controller operatively associated with the drive assemblies to coordinate the assemblies.

2. The machine of claim 1, further including a pair of cooperating stripper bars, each stripper bar being operatively associated with a respective one of the jaws to move therewith to strip the tubular bag material.

3. The machine of claim 1, further including a pair of tube closer bars, each of the closer bars being operatively associated with a respective one of the jaws to engage the tubular bag material to close the tubular bag material.

4. The machine of claim 1, wherein said jaw drive assembly is mounted on said carriage.

5. The machine of claim 1, wherein said carriage drive assembly is a linear motor at least partly mounted on said base and at least partly mounted on said carriage, so that said carriage when reciprocated moves along a generally linear path.

6. The machine of claim 1, wherein each jaw is attached to its respective shaft by a jaw support.

7. The machine of claim 6, wherein each jaw support includes at least one arm extending generally radially relative to its respective shaft.

8. The machine of claim 6, wherein each jaw is fixed relative to its respective support.

9. The machine of claim 6, wherein each jaw is attached to its respective shaft by a support, with each jaw being mounted on its respective support for angular movement relative thereto about an axis generally transverse of said direction.

10. The machine of claim 9, wherein the jaws are attached by guides so that the jaws move in unison in opposite directions while facing each other.

11. The machine of claim 1, wherein the jaws are mounted on their respective supports for movement relative thereto in a radial direction.

12. The machine of claim 1, wherein said carriage includes a pair of generally parallel walls between which said shafts extend, and an end wall adjacent said base and including portion of said linear motor.