Seal bar assembly

BACKGROUND OF THE INVENTION

[0001] A. Field of the Invention

[0002] The present invention relates to a seal bar assembly for use in connection with vacuum packaging machines and more particularly, a seal bar that is actuated by an air bladder and that is mounted to floating guide shafts, which provide the primary electrical connection to the seal bar by using an electrical shaft connector.

[0003] B. Description of the Related Art

[0004] Manufacturers often desire to package their products in air-tight or shrink-wrapped bags. For example, a manufacturer may wish to seal a food product in an air-tight package to ensure its freshness or may wish to vacuum pack a compressible product in order to reduce the size of the packaging for shipping and handling. Also, it is sometimes either too expensive to package a product in a box or desirable to visibly display the product. In these cases, the manufacturer may shrink-wrap the product in a clear or colored plastic bag. This type of packaging allows the consumer in some instances, to see the product, protects the product during shipping and, in certain instances, when the content can be compressed through the vacuum packaging process, reduces the size of the package.

[0005] Currently, machinery is available for packaging products in air-tight bags. This machinery typically comprises a base member having an upstanding wall defining an internal cavity in which a bagged product may be placed. A lid is movable over the base, the lid having a perimeter sealing element for forming a seal against the top of the wall of the base.

[0006] A movable cutting element is connected to the lid for cutting the bar so that air can be removed from the bag. Means are provided for evacuating the air from the cavity. Additionally, a heated element is connected to the lid via a seal bar for sealing the bag after the air is evacuated from the bag.

[0007] Since the heating element of the seal bar must be heated to seal the package after the air is evacuated from the bag, all seal bars in vacuum packaging machines must have an electrical connection. Typically, each machine requires at least two (2) electrical connections which are made to the ends of the seal bars to provide power to the heating element.

[0008] Additionally, all seal bars have some type of linear motion actuation to extend the seal bar downwardly or upwardly to engage the sealing process after vacuum is reached in the machine. Linear actuation is generally accomplished in one of two ways: (1) an inflatable air bladder or (2) air/vacuum cylinders. Each of these actuating devices has advantages and disadvantages.

[0009] In the case of air/vacuum cylinders, the cylinders provide a smooth mechanical movement and the ability to make the electrical connections to the seal bar through the central cylinder shaft. Thus, an electrical connection directly to the seal bar is not necessary since there is no relative motion between the cylinders and the seal bar. Both the cylinders and the seal bar move together.

[0010] When using cylinders, an electrical shaft power connector is placed in the seal bar and the connection is made when the seal bar is slipped over the cylinder shaft, providing a clean wireless connection to the seal bar. By not having a direct electrical connection to the seal bar, the seal bar may be removed quickly for cleaning of the machine when used in a food environment. One disadvantage with cylinders are that the applied sealing force is limited and the cost is high.

[0011] In contrast, bladders provide a high sealing force at a very low cost. However, the bladders require a separate wire connection to the seal bar because the seal bar is typically moving over a guide shaft or pin so that an electrical connection cannot be maintained. Thus, while bladders provide high sealing force at a low cost as compared to cylinders, the use of bladders does not allow for the easy removal of the seal bar for cleaning since the electrical connection is made directly to the seal bar.

[0012] A need therefore exists for a seal bar that utilizes a bladder, but that provides for the easy removal of the seal bar for cleaning.

SUMMARY OF THE INVENTION

[0013] The present invention is a seal bar assembly for use in connection with a vacuum packaging machine. The seal bar assembly includes an elongated seal bar, having a heating wire extending across the seal bar and an air bladder to move the seal bar from its resting position to its extended position to seal the packaging bags. The seal bar is mounted to two floating guide shafts—one at each end of the seal bar. The seal bar is mounted onto the shaft by using spring loaded detent screws or thumb screws. The floating guide shafts are then mounted to the base of the container.

[0014] At the ends of the guide shafts that oppose the sealing bar are electrical connectors that serve as the wire connection for the seal bar assembly. Electrical wires extend from the wire connectors through the base, as determined by the machine design, to a power source for providing power to the sealing bar assembly to heat the heating wire.

[0015] In one embodiment of the present invention, a seal bar, of the type known in the art, is mounted to the lid of the vacuum packaging machine. A seal bar of the present invention is also mounted to the base of the machine to provide dual sealing action. Thus, after the air in the bag is evacuated, the seal bar mounted to the lid is heated to seal the packaging bag. At the same time, the seal bar mounted to the base is extended upwardly to contact and seal the packaging bag from its underside.

[0016] The seal bar of the present invention is preferably mounted to the base, although in alternative embodiments it may be mounted to the lid. In either case, the seal bar is moved, upward or downward, as the case may be, through the use of an air bladder, i.e., actuating device. When the air bladder is inflated, the seal bar is extended to contact and seal the bag. The air bladder is then deflated and the seal bar is returned to its resting position through the use of return springs which are mounted to each guide shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] A more complete appreciation of the invention and many of the advantages thereof will be readily obtained as the same becomes better understood by references to the detailed description when considered in connection with the accompanying drawings, wherein:

[0018]
FIG. 1 is a front view of a vacuum packaging machine utilizing a seal bar of one embodiment of the present invention with the lid and base for the machine partially cut away to show the seal bar positioned therein in its retracted position;

[0019]
FIG. 2 is a cross-sectional side view of the apparatus of FIG. 1 taken along line 2-2 thereof showing the seal bar in its retracted position;

[0020]
FIG. 3 is a side prospective view of the seal bar assembly of one embodiment of the present invention;

[0021]
FIG. 4 is a side exploded perspective view of the seal bar assembly illustrated in FIG. 5;

[0022]
FIG. 5 is a front view of a vacuum packaging machine utilizing a seal bar of one embodiment of the present invention with the lid and base for the machine partially cut away to show the seal bar positioned therein in its extended position; and

[0023]
FIG. 6 is a cross-sectional side view of the apparatus of FIG. 3 taken along line 3-3 thereof showing the seal bar in its extended position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0024] As illustrated by FIG. 1, the present invention is a seal bar assembly 10 for use in connection with a vacuum packaging machine 12 designed to vacuum pack products that are not subject to reduction, such as food products, as well as items that are subject to reduction through vacuum packaging, such as clothing, outdoor wear, sleeping bags, other fabric derived products and other flexible, resilient compressible materials.

[0025] As illustrated by FIG. 1, the vacuum packaging machine 12 of the present invention typically comprises a base 16 member having an upstanding wall defining an internal cavity 18 in which a bagged product may be placed. A lid 14 is movable over the base 16 and has a perimeter sealing element for forming a seal against the top of the wall of the base 16 when the lid 14 is closed over the base 16. The vacuum packaging machine 12 includes means (not shown) for evacuating the air from the internal cavity 18 of the vacuum packaging machine 12, as is well known in the art.

[0026] In one embodiment of the present invention, a seal bar 28, of the type known in the art, is mounted to the lid 14 of the vacuum packaging machine 12. A seal bar 10 of the present invention is also mounted to the base 16 of the machine to provide dual sealing action. Thus, after the air in the bag is evacuated, the seal bar 28 mounted to the lid 14 is heated. Similarly, the seal bar 10 of the present invention mounted to the base 16 is heated and extended upwardly to contact and seal the packaging bag from its underside.

[0027] While the seal bar 10 of the present invention is preferably mounted to the base 16, in alternative embodiments the seal bar 10 may be mounted to the lid 14. In either case, the seal bar assembly 10 is moved, upward or downward, as the case may be, through the use of an air bladder, i.e., actuating device.

[0028] As illustrated in FIG. 2, which is a side perspective view of the seal bar assembly 10 of one embodiment of the present invention, the seal bar 28, of the type known in the art, is mounted to the lid 14 of the vacuum packaging machine 12 and is used in conjunction with a combined cutting blade 20 and heat bar 22. The lid 14 mounted cutting blade 20 and heat bar 22 are connected to an actuating means, such as an expandable air bladder (not shown), for movement with respect to the lid 14.

[0029] The seal bar assembly 10 of the present invention is mounted to the base 16 of the vacuum packaging machine 12 and includes an elongated seal bar 30, preferably constructed of a lightweight resin material, or other like material, having a heating wire 32 extending across the seal bar 30 and a bar lift 34 for contact with the air bladder (not shown) to actuate the seal bar 30 and move the seal bar 30 from its resting position to its extended position to seal the packaging bags. The heating wire 32 is mounted to the seal bar 30. The heating wire 32 is generally constructed of metal, and has a rectangular cross-section and is secured to the seal bar 30 in a manner known in the art. The heating wire 32 typically has a cover 54, which extends over the heating wire 32 to prevent direct contact of the heating wire 32 with the packaging bag (not shown). The cover 54 is preferably a Teflon(tm) tape formed into a ‘U’-shape. The tape is connected to each side of the seal bar 30 and extends across the top edge 31 of the seal bar 30.

[0030] As best illustrated by FIGS. 3 & 4, the seal bar 10 is mounted to two floating guide shafts 40—one at each end of the seal bar 30. These guide shafts 40 act as the electrical conduit to make the power connection to the seal bar 30 and comprise a shaft type connector 46, a guide pin 48 and a nylon pin guide 50. The floating guide shafts 40 are secured to the seal bar 10 through the use of thumb screws 42 or spring loaded detent screws. The floating guide shafts 40 are then mounted to the base 16 of the vacuum packaging machine 12.

[0031] At the ends of the guide shafts 40 that oppose the sealing bar 30 are electrical connectors 44 that serve as the wire connection for the seal bar assembly 10. Electrical wires (not shown) extend from the wire connectors 44 through the base 14, as determined by the machine design, to a power source (not shown) for providing power to the sealing bar assembly 10 to heat the heating wire 32.

[0032] As illustrated by FIGS. 3 and 4, the floating guide shafts 40 also include return springs 52, which are located at the bottom of the floating guide shaft 40 assembly between the guide pin 48 and wire connector 44. The return springs 52 assist the seal bar assembly 10 in returning to its resting position after being extended to seal a package.

[0033] The actuating mechanism comprises a means for moving/actuating the seal bar 30 between a first (retracted) (FIG. 2) and a second (extended) (FIG. 6) position. Preferably, the actuating mechanism comprises an air bladder (not shown). The air bladder includes an inflatable element, such as a section of firehose or similar durable expandable material. The inflatable element is mounted just under bar lift 34 of the seal bar 30.

[0034] An air line extends through the base 16, and into the inflatable element of the air bladder. The air line is connected to a source of high and low pressure air for inflating and deflating the air bladder and thereby extending the seal bar 30 and allow for it to retract into its resting position.

[0035] While one embodiment to the present invention uses a heating bar 12 that is separately actuated from the cutting blade 10, which is mounted on a separate seal bar assembly on the lid 14 of the vacuum packaging machine 12, the present invention may also utilize a combination heating bar 12 and cutting blade 10, actuated by a single actuator 14, such as an air bladder 36. Furthermore, one skilled in the art can modify the arrangement of the cutting blade 10 and the heating bar 12 to be utilized in a chamberless vacuum packaging machine 18 or in other types of vacuum packing machines 18.

[0036] In operation, the user opens the lid 14 of the vacuum packaging machine 12 fitted with the seal bar assembly 10 of one embodiment of the present invention, as illustrated in FIGS. 1 and 2. The user positions an item to be sealed with a bag (not shown) and places the bag in the cavity 18 within the base 16 of the vacuum packaging machine 12, extending the open end of the bag outside of the machine 12.

[0037] The user then closes the lid 16, as illustrated in FIGS. 1 and 2. A seal on the lid 14 seals the lid 14 against the base 16. A slight vacuum is then drawn, evacuating some of the air from within the cavity 18. This partial vacuum is drawn in order to better seal the lid 14 to the base 16, and to prevent the lid 14 from raising when the cutting blade 20 is lowered and cuts the bag. Care is taken, however, not to draw an excessive vacuum, as such could have the effect of rupturing the bag, as the air within the bag at that time has no path of escape.

[0038] The combined cutting bar 20 and heat bar 22, which is mounted to the lid in one embodiment of the present invention, as illustrated by FIGS. 1 and 2 and FIGS. 5 and 6, is then lowered into the position illustrated in FIG. 6. In particular, air is forced through the air line into the inflatable element of the air bladder. Inflation of the air bladder 36 presses the seal bar 30 upward until it engages a stop, as illustrated in FIG. 6.

[0039] Most importantly, at this time the heat bar 22 of the seal bar 28 and heating wire 32 of the seal bar 30 are unheated during the initial cut. When in the extended position, the cutting blade 20 of the seal bar 28 cuts the bag, forming spaced slits therein. After the slits are cut, if air bladders are being used as the actuating means, air is then removed from the air bladders through the air line, the air bladder collapsing and the force of the return springs 52 generated by the springs 52 from the pressing of the mechanism upwardly or downwardly from the lid or base as illustrated in FIG. 6. At the same time, full vacuum is drawn within the vacuum packaging machine 12, drawing the remaining air from the cavity 18 and the bag. The air in the bag escapes through the slits cut in it by the cutting blade 20.

[0040] The heat wire 52 of the lower seal bar 30 and the heat bar 22 of the upper seal bar 28 are then heated. The upper seal bar 28 is then lowered to the position illustrated in FIG. 6 and the lower seal bar 30 is then extended upwardly as illustrated in FIG. 6. At this time, the heating wire 52 of lower seal bar 30 melts the bag from the bottom and the heat bar 22 of the upper seal bar 28 heats the bag from the top.

[0041] The lower seal bar 30 is then again lowered. Air is returned to the cavity 18, such as by venting to the outside atmosphere, and the user opens the lid. The user then removes the sealed bag.

[0042] The sequence of (1) pulling initial vacuum; (2) lowering the seal bar 28 to cut the bag; (3) raising the seal bar 28 and pulling full vacuum; (4) heating the heating bar 22 of the upper seal bar 28 and lowering to seal bar 28 to melt the bag; (5) simultaneously heating the heating wire 32 of the lower seal bar 30 and extending the seal bar 30 upward to melt the bag; and (6) raising the seal bars 20 and 30 is preferably accomplished with relays or the like so as to be automatic.

[0043] When used in the food packaging industry, the seal bar 30 may be easily removed for cleaning by loosening thumb screws 42. With the thumb screws 42 loosened, the seal bar 30 will slip off the guide shafts 40, with no wire attachments.

[0044] Further, the specific configuration of the heat bar could be changed substantially without falling from the scope of the invention. A wide variety of heating elements are well known in the art, and may be employed instead of the one described herein. In addition, a cutting blade as shown in the seal bar assembly mounted to the lid of the vacuum packaging machine may be added to or used in connection with the above invention.

[0045] It will be understood that the above described arrangements of apparatus and the method therefrom are merely illustrative of applications of the principles of this invention and many other embodiments and modifications may be made without departing from the spirit and scope of the invention as defined in the claims. For example, both the upper and the lower seal bars may utilize guide shafts having electrical wire connections and an air bladder for actuating the seal bar. Alternatively, only one seal bar may utilize the guide shafts of the present invention while the other seal bar utilizes more traditional actuating mechanisms, such as an air bladder and arm. Similarly, the seal bar of the present invention may be used on the top lid or the bottom lid (as described herein) with opposing seal bars, or opposing backup bars, i.e., a seal bar without a heating element.

Seal bar assembly

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