Sealing System for a Packaging Apparatus

Abstract

A sealing jaw apparatus for a film wrapping machine utilizes a continuous web of thermoplastic film. The sealing jaw apparatus includes a first jaw unit to one side of a film travel path. The first jaw unit includes spaced-apart clamp arms and a heated sealing bar located between the spaced-apart clamp arms. The heated sealing bar includes spaced-apart noses defining a slot therebetween. A second jaw unit is to an opposite side of the film travel path. The second jaw unit includes spaced-apart gripping surfaces that are engaged by the spaced-apart clamp arms for gripping the thermoplastic film. Spaced-apart sealing surfaces are engaged by the noses of the heated sealing bar for sealing the thermoplastic film at spaced-apart locations in a film running direction. A knife assembly severs the thermoplastic film between the spaced-apart locations.

Description

TECHNICAL FIELD

The present application relates to packaging apparatus and more particularly to a sealing system for a packaging apparatus.

BACKGROUND

Packaging apparatus have been provided that are used to seal product within wrapped film. Typically, a film sheet is formed into a tube or folded and product is placed in the tube or folded film. A sealing system is used to seal and sever the tube or folded film to form a bag with product located therein that is separated from the film sheet.

U.S. Pat. No. 5,131,213 provides a sealing jaw apparatus for a plastic film wrapping machine. The sealing jaw apparatus provides a heated sealing jaw with a reciprocal knife. The jaw operates against a heated elastomeric bed that has a slot to receive the knife during a cutting operation.

SUMMARY

In an aspect, a sealing jaw apparatus for a film wrapping machine utilizes a continuous web of thermoplastic film. The sealing jaw apparatus includes a first jaw unit to one side of a film travel path. The first jaw unit includes spaced-apart clamp arms and a heated sealing bar located between the spaced-apart clamp arms. The heated sealing bar includes spaced-apart noses defining a slot therebetween. A second jaw unit is to an opposite side of the film travel path. The second jaw unit includes spaced-apart gripping surfaces that are engaged by the spaced-apart clamp arms for gripping the thermoplastic film. Spaced-apart sealing surfaces are engaged by the noses of the heated sealing bar for sealing the thermoplastic film at spaced-apart locations in a film running direction. A knife assembly severs the thermoplastic film between the spaced-apart locations.

In another aspect, a method of sealing layers of plastic film from a continuous film web is provided. The method includes engaging the layers between a first jaw unit and a second jaw unit. The first jaw unit includes spaced-apart clamp arms that engage spaced-apart gripping surfaces of the second jaw unit. The layers are sealed at two seal locations that are spaced-apart in a web running direction using a heated sealing bar carried by the first jaw unit and located between the spaced-apart clamp arms. The sealing bar includes spaced-apart noses defining a slot therebetween. The spaced-apart noses engage spaced-apart sealing surfaces carried by the second jaw unit. The layers are severed between the first and second seal locations using a knife assembly carried by the second jaw unit.

In another aspect, a sealing jaw apparatus for a film wrapping machine utilizes a continuous web of thermoplastic film. The sealing jaw apparatus includes a first jaw unit to one side of a film travel path. The first jaw unit includes spaced-apart clamp arms and a heated sealing bar located between the spaced-apart clamp arms. The heated sealing bar includes spaced-apart noses defining a slot therebetween. A second jaw unit is to an opposite side of the film travel path. The second jaw unit includes spaced-apart gripping surfaces that are engaged by the spaced-apart clamp arms for gripping the thermoplastic film and spaced-apart sealing surfaces that are engaged by the noses of the heated sealing bar for sealing the thermoplastic film at spaced-apart locations in a film running direction. A knife assembly is provided for severing the thermoplastic film between the spaced-apart locations. The heated sealing bar moves relative to the knife assembly to bring the noses into contact with the spaced-apart sealing surfaces.

The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 1a are diagrammatic, side section views of an embodiment of a sealing system for use in a packaging apparatus; and

FIGS. 2-5 illustrate the sealing system of FIG. 1 in use.

DETAILED DESCRIPTION

Referring to FIGS. 1 and 1a, a sealing system 10 for use in a packaging apparatus includes a first sealing jaw 12 and a second, opposing sealing jaw 14. It should be noted that while the sealing jaws 12 and 14 are illustrated as being operated horizontally (i.e., to sever and seal vertically oriented film material), the sealing jaws may also be operated vertically (i.e., to sever and seal horizontally oriented film material). In addition, an L-shaped sealing system is also contemplated for simultaneously sealing film along two intersecting edges.

The first sealing jaw 12 includes outer, spaced-apart clamp arms 16 and 18. The clamp arms 16 and 18 have a respective gripping member 20 and 22 that is used to grip the film material. The gripping members 20 and 22 may be formed of a resilient material such as an elastomer or rubber and may be press fit or otherwise attached within grooves 24 and 26 in the clamp arms 16 and 18. The gripping members 20 and 22 may also include contoured gripping surfaces 28 and 30, for example, having two peaks separated by a valley as shown in FIG. 1.

Located between the spaced-apart clamp arms 16 and 18 is a heated sealing bar 32. The sealing bar 32 is heated by a heating element 34 located between sealing bar members 36 and 38. Each sealing arm member 36 and 38 includes a respective nose 40 and 42 separated from each other thereby defining a slot 44 therebetween. As will be described below, the sealing bar 32 is extendable and retractable relative to the spaced-apart clamp arms 16 and 18. The sealing bar 32 may be moveable using a linear actuator, such as a pneumatic cylinder. In some embodiments, the sealing bar 32 is biased (e.g., using a spring) toward the retracted position shown in FIG. 1.

The second sealing jaw 14 opposes the first sealing jaw 12. The second sealing jaw 14 includes support members 46 and 48 (e.g., formed of metal, such as aluminum or steel) that are arranged to engage with the gripping surfaces 28, 30 of the spaced-apart clamp arms 16 and 18. The support members 46 and 48 also provide support for sealing members 50 and 52, which are located within recesses 58 and 60 formed in the support members. The sealing members 50, 52 provide sealing surfaces 54 and 56 that engage the noses 40 and 42 of the heated sealing bar 32. In some embodiments, the sealing members 46 and 48 are formed of a resilient material, such as rubber.

A knife assembly 62 is carried by the second sealing jaw 14. The knife assembly 62 includes a blade 64 and a blade clamp 66. As shown in FIG. 1, the knife assembly 62 is in its retracted position with a cutting edge 68 of the blade 64 being recessed with respect to the sealing surfaces 54 and 56 within a slot 70 formed between the sealing surfaces of the sealing members 50 and 52. As will be described in greater detail below, the knife assembly 62 can be extended relative to the sealing members 50, 52 to position the cutting edge 68 beyond the sealing surfaces 54, 56 and into the slot 44 between the noses 40, 42 of the sealing bar 32. In some embodiments, the knife assembly 62 is extended and retracted using a pneumatic cylinder 71 capable of delivering pressurized air into a rear chamber 72 behind the knife assembly. Other configurations are contemplated for extending and retracting the knife assembly, such as a hydraulic cylinder. In some embodiments, the knife assembly may be connected to an output shaft of the cylinder.

Referring now to FIG. 2, a film sheet 74 including layers 75, 77 is located along a film path between the first sealing jaw 12 and the second sealing jaw 14. A product 76 may be located between sides 78 and 80 of the folded film sheet 74, below the sealing jaws 12 and 14.

Referring to FIG. 3, the first and second gripping jaws 12 and 14 come into contact and the spaced-apart clamp arms 16 and 18 with gripping members 20 and 22 engage the support members 46 and 48 thereby gripping the film layers therebetween at locations on opposite sides of the knife assembly 62, holding the folded film taught for sealing and cutting operations. In this regard, one or both of the jaws 12 and 14 may be moveable toward and away from the other jaw for this purpose.

Referring to FIG. 4, the sealing bar 32 is brought into engagement with the sealing members 50 and 52 with the noses 40 and 42 applying pressure against the film layers on either side of the knife assembly 62. In some embodiments, the noses 40 and 42 engage the sealing members within a central portion of the sealing members spaced from the side corners of the sealing members. The sealing bar 32 is heated and heat seals the film layers along two transversely extending lines that are spaced-apart from each other in the web running direction. The lower seal line is a top seal for portion 82 of the film 74 and the upper seal line is a bottom seal for the upper portion 83 of the film. As can be seen, the knife assembly 62 is in its retracted position with the cutting edge 68 recessed behind the sealing surfaces 54 and 56.

Referring to FIG. 5, the knife assembly 62 is actuated to extend the knife blade 64 into the slot 44 formed between the noses 40 and 42 of the sealing bar 32. This actuation severs the film layers between the upper and lower seal lines. Once the film 74 is severed, the sealing assembly 10 returns to its original position as shown by FIG. 2.

The above-described sealing system 10 can provide a low energy system operating at temperatures between about 180° F. and about 220° F. Advantageously, the knife assembly is located on the jaw opposite the heated sealing bar.

It is to be clearly understood that the above description is intended by way of illustration and example only and is not intended to be taken by way of limitation, and that changes and modifications are possible. Accordingly, other embodiments are within the scope of the following claims.

Claims

1. A sealing jaw apparatus for a film wrapping machine utilizing a continuous web of thermoplastic film, the sealing jaw apparatus comprising:

a first jaw unit to one side of a film travel path, the first jaw unit comprising spaced-apart clamp arms and a heated sealing bar located between the spaced-apart clamp arms, the heated sealing bar including spaced-apart noses defining a slot therebetween; and

a second jaw unit to an opposite side of the film travel path, the second jaw unit comprising spaced-apart gripping surfaces that are engaged by the spaced-apart clamp arms for gripping the thermoplastic film, spaced-apart sealing surfaces that are engaged by the noses of the heated sealing bar for sealing the thermoplastic film at spaced-apart locations in a film running direction, and a knife assembly for severing the thermoplastic film between the spaced-apart locations.

2. The sealing jaw apparatus of claim 1, wherein the knife assembly is moveable between a retracted position where a cutting edge of the knife assembly is recessed from the sealing surfaces within a slot defined therebetween and an extended position where the cutting edge is extended beyond the sealing surfaces and into the slot between the noses.

3. The sealing jaw apparatus of claim 2 further comprising an actuator carried by the second sealing jaw unit that extends the knife assembly.

4. The sealing jaw apparatus of claim 1 further comprising metal support members carried by the second jaw unit that define the gripping surfaces.

5. The sealing jaw apparatus of claim 4 further comprising sealing members connected to the metal support members, the sealing members formed of an elastic material and forming the sealing surfaces.

6. The sealing jaw apparatus of claim 4, wherein the sealing members are located within respective recesses formed in the metal support members.

7. The sealing jaw apparatus of claim 1, wherein the clamp arms each include a gripping member located at an end of the clamping arm, the gripping member including a contoured end surface that engages the gripping surface.

8. The sealing jaw apparatus of claim 3, wherein at least one of the first and second jaw units is moveable toward and away from the other of the first and second jaw units.

9. The sealing jaw apparatus of claim 8, wherein the apparatus operates such that the knife assembly is maintained in the retracted position until the noses engage the spaced-apart sealing surfaces.

10. A method of sealing layers of plastic film from a continuous film web, the method comprising:

engaging the layers between a first jaw unit and a second jaw unit, the first jaw unit comprising spaced-apart clamp arms that engage spaced-apart gripping surfaces of the second jaw unit;

sealing the layers at two seal locations that are spaced-apart in a web running direction using a heated sealing bar carried by the first jaw unit and located between the spaced-apart clamp arms, the sealing bar including spaced-apart noses defining a slot therebetween, the spaced-apart noses engaging spaced-apart sealing surfaces carried by the second jaw unit; and

severing the layers between the first and second seal locations using a knife assembly carried by the second jaw unit.

11. The method of claim 10, wherein the step of severing the layers includes extending the knife assembly from a retracted position where a cutting edge of the knife assembly is recessed from the sealing surfaces within a slot defined therebetween, beyond the sealing surfaces and into the slot between the noses.

12. The method of claim 11, wherein the step of severing the layers occurs after the step of sealing the layers.

13. The method of claim 11, wherein the knife assembly is extended using an actuator carried by the second jaw unit.

14. The method of claim 10, wherein the step of sealing the layers at two seal locations further includes, after the spaced-apart clamp arms engage the spaced-apart gripping surfaces of the second jaw unit, extending the heated sealing bar relative to the clamp arms until the spaced-apart noses engage spaced-apart sealing surfaces carried by the second jaw unit.

15. The method of claim 14, wherein the step of extending the heated sealing bar includes extending the heated sealing bar relative to the knife assembly.

16. A sealing jaw apparatus for a film wrapping machine utilizing a continuous web of thermoplastic film, the sealing jaw apparatus comprising:

a first jaw unit to one side of a film travel path, the first jaw unit comprising spaced-apart clamp arms and a heated sealing bar located between the spaced-apart clamp arms, the heated sealing bar including spaced-apart noses defining a slot therebetween; and

a second jaw unit to an opposite side of the film travel path, the second jaw unit comprising spaced-apart gripping surfaces that are engaged by the spaced-apart clamp arms for gripping the thermoplastic film and spaced-apart sealing surfaces that are engaged by the noses of the heated sealing bar for sealing the thermoplastic film at spaced-apart locations in a film running direction; and

a knife assembly for severing the thermoplastic film between the spaced-apart locations;

wherein the heated sealing bar moves relative to the knife assembly to bring the noses into contact with the spaced-apart sealing surfaces.

17. The sealing jaw apparatus of claim 16, wherein the knife assembly is carried by the second jaw and is moveable between a retracted position where a cutting edge of the knife assembly is recessed from the sealing surfaces within a slot defined therebetween and an extended position where the cutting edge is extended beyond the sealing surfaces and into the slot between the noses.

18. The sealing jaw apparatus of claim 17 further comprising an actuator carried by the second sealing jaw unit that extends the knife assembly.

19. The sealing jaw apparatus of claim 16, wherein the clamp arms each include a gripping member located at an end of the clamping arm, the gripping member including a contoured end surface that engages the gripping surface.

20. The sealing jaw apparatus of claim 16 further comprising metal support members carried by the second jaw unit that define the gripping surfaces.