TECHNICAL FIELD

The present invention relates to an apparatus for

sealing and creasing a fin of a gabled container.

Specifically, the invention relates to a sealing

configuration on the face of one or more sealing jaws

that both seals the fin and, further, forms a fin base

crease that assists in maintaining the integrity of the

fin shape and seal.

PACKgRQTTN Gable top cartons have been known for the better

part of the twentieth century. Their characteristic

simplicity and resealability have helped to sustain their popularity as cartons for traditional liquid food

products such as milk and juice, but in recent years

they have been used for products ranging from ammunition

to Epsom salts. Gable top cartons typically start out

as generally rectangular carton blanks made of creases

to facilitate folding and forming the blank into a

carton.

During decades of development, manufacturers o

packaging machines have devised a variety of ways t

form, fill, and seal gable top cartons. Today, the mos prevalent packaging machines for filling and sealin

gable top cartons are adapted to receive the carto

blank after it has been side sealed. The process o

side sealing involves sealing opposite vertical edges o

the carton blank together to form a polygonal (usuall

rectangular) sleeve. The sleeve is received on a

indexable mandrel wheel which rotates the sleeve int respective positions where the end of the sleev extending outwardly from the mandrel is folded an

sealed to form the bottom of the carton.

After the carton bottom has been formed, it i removed from the mandrel and transported to a fillin

station where the carton is filled with product. Onc

the carton has been filled, the top of the carton i

folded into the familiar gable top configuration and i heat sealed, thus completing the packaging process.

One example of a known packaging machine tha

operates generally in accordance with these principle is described in U.S. Patent No. 3,789,746 to Martensso et al. Other examples of such packaging machines ar

described in U.S. Patent No. 3,820,303 to Martensson et

al., U.S. Patent No. 4,759,171 to Bruveris et al. , and

U.S. Patent No. 4,790,123 to Ljungstrom et al. These patents are hereby incorporated by reference.

Various mechanisms are known for sealing the fin at

the gabled end of the gable top carton. One such

mechanism is disclosed in U.S. Patent No. 3,200,557 to Schwenk. In accordance with the teachings of that

patent, the upper flap panels that form the gabled

structure, including the fin, are first heated to allow

the polyethylene coating on the cartons to soften. The carton is then transported to a position between two

sealing jaws. The sealing jaws move toward one another and apply pressure to form and seal the fin. Fins that are sealed in accordance with the

teachings of the foregoing patents have a tendency to separate in the region below the principal horizontal

seal. Additionally, the process of heat sealing the fin of the gabled container can be time consuming and limits

the throughput of the packaging machine. An improved

sealing apparatus is therefore desirable.

SUMMARY OF THE INVENTION

A sealing device is set forth which assists in

overcoming the foregoing problems. The sealing device

includes a first sealing jaw for sealing a fin of the

gabled container. A second sealing jaw is disposed

opposite the first sealing jaw. Both the first and

second sealing jaws include a generally flat face

portion. The second sealing jaw further includes a

sealing bar extending from a raid-region of its generally

flat face portion lengthwise along at least a portion

thereof for sealing the fin of the gabled container

with, for example, ultrasonic energy. A ridge extends

respectively from each of the generally flat face

portions at a position to form a fin base crease at the

base of the fin, for example, over the existing weak

crease at the base of the fin. The fin base crease assists in preventing separation at the base of the fin

below the principal horizontal seal formed by the

sealing bar. The sealing bar may extend from the

generally flat face portion of the second jaw a distance

beyond the degree to which the ridges extend from their

respective face portions. The ridges thus may exert less

pressure on the fin than does the sealing bar.

In accordance with a further embodiment of the

sealing jaws, the sealing bar is replaced by a plurality of generally circular sealing extensions. By using a

plurality of generally circular sealing extensions, it

becomes possible to better regulate the amount of

ultrasonic energy transmitted to the fin, thereby

providing the ability to make the heat sealing process

more time and energy efficient.

In accordance with a still further embodiment of the sealing jaws, the degree to which the ridges and

circular extensions protrude from the generally flat face portions is reduced proximate the opening end of

the fin. This facilitates opening of the gabled container while ensuring proper fin sealing.

A method of using the sealing jaws and a gable top

configuration sealed with the sealing jaws are likewise contemplated. Other advantages of the present invention

will become apparent upon reference to the accompanying

detailed description in conjunction with the following

drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a first jaw.

FIG. 2 is a perspective view of a second jaw.

FIG. 3 is a side view of the first and second jaws

in an opened condition with a fin disposed therebetween.

FIG. 4 is a side view showing the jaws of FIG. 3 in

the closed position engaging the fin a of gabled

container.

FIG. 5 is a side view of a further embodiment of

the first and second jaws.

FIG. 6 and 7 illustrate a fin that has been sealed

using the disclosed sealing jaws.

FIG. 8 is a top plan view of the second jaw showing

the sealing extensions. FIG. 9 is a top plan view of the first jaw showing

the ridge extension.

FIG. 10 is a perspective view of an alternative

embodiment of the first and second jaws.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGs. 1 and 2 illustrate a first jaw 20 and a

second jaw 25 respectively. The first and second jaws

20, 25 may be used in an ultrasonic sealing mechanism

such as the one disclosed in U.S.S.N. 08/315,412

(Attorney Docket No. 10454US01; Corporate Docket No.

TRX-0082) , entitled "Ultrasonic Carton Sealer", filed on

even date herewith, and which is hereby incorporated by

reference. As illustrated, the first jaw 20 includes a

generally flat face portion 30. A ridge 35 extends

outwardly from the generally flat face portion 30 at a

lower region thereof.

The second jaw 25 likewise includes a generally

flat face portion 40. A ridge 35 extends outwardly from

the generally flat face portion 40 at a lower region

thereof. A plurality of generally circular sealing

extensions 45 extend outwardly from the generally flat

face portion 40 in a region disposed above the ridge 35.

The degree to which the sealing extensions 45 extend

from the face portion 40 is greater than the degree to

which the ridges 35 extend from their respective face

portions 30 and 40.

FIGs. 3 and 4 illustrate the relative position of the first jaw 20 and second jaw 25 in an open condition

with a fin 50 of a gabled container disposed

therebetween. As illustrated, the generally circular sealing extensions 45 are disposed proximate a mid-

region of the fin while the ridges 35, illustrated here

as having a generally curved cross-section, reach an

apex that is disposed proximate the base of the fin 50. The juxtaposed jaws 20 and 25 are movable toward one another in the directions illustrated by arrows 55 and away from one another in the direction illustrated by arrows 60.

FIG. 4 illustrates the jaws 20 and 25 in a closed

state. In this closed state, the jaw 25, which may, for

example, be an ultrasonic horn, transmits ultrasonic energy to the fin 50 for a predetermined period of time which causes the polyolefin barrier layers of juxtaposed

fin contacting surfaces 65 and 70 to soften so that the

surfaces may be joined together in the area of the generally circular extensions 45. Use of the plurality of generally circular sealing extensions, as opposed to

a single ridge, facilitates a high degree of control

over the amount of ultrasonic energy used to seal the

fin 50. Such control, further, reduces the amount of

time required to cool the fin 50 after the predetermined

period of time in which ultrasonic energy is applied.

At the same time that a seal is formed by the circular extensions 45, the ridges 35 engage the base of

the fin to form a crisp fin base crease, for example,

over the existing weak creases at the base of the fin .

Due to the difference in the degree to which the ridges

35 and sealing extensions 45 extend, the pressure

applied by the ridges 35 to form the crisp fin base crease is less than the pressure applied by the circular

extension 45. As such, the amount of ultrasonic energy

transmitted to the fin 50 in the base region is less

than the amount of ultrasonic energy transmitted to the fin in the sealing region.

FIG. 5 illustrates a further embodiment of the

first and second jaws 20 and 25. In this embodiment, the ridges 35 have a trapezoidal cross-section which

may, for example, provide a more defined crease than the

ridges 35 illustrated in FIGs. 3 and 4. As in the previous embodiment, the ridges do not extend to the same degree as the sealing extensions.

FIGs. 6 and 7 illustrate the gabled end 80 of a

container 85 wherein the fin 50 has been sealed with the

disclosed first and second sealing jaws 20 and 25. As

illustrated, the fin 50 extends lengthwise from an opening end 90 to a closed end 95. A plurality of

circular sealing regions 100 are disposed lengthwise along the mid-portion of the fin to form the primary

seal. The fin base crease 105 extends lengthwise along the base of the fin 50.

A uniform seal along the length of the fin may not

be desirable where, for example, the gabled top has an opening end and a closed end. Rather, it may be

desirable to provide a seal that is more easily opened

at the opening end 90 than the closed end 95. FIGs. 8 and 9 illustrate modifications to the circular extensions 45 and ridges 35 to accomplish this goal. As illustrated, the generally circular extensions taper to

a diminished degree of extension in region 110 while the

ridges 35 likewise taper to a diminished degree of extension in region 115. Regions 110 and 115 are

disposed proximate the opening end 90 of the fin when

the first and second jaws 20 and 25 are closed to seal

and crease the fin 50. Less ultrasonic energy will thus

be applied in the regions 110 and 115 thereby providing

a seal at the opening end 90 that is more readily broken

than the seal at the closed end 95.

An alternative embodiment of the first and second

jaws 120 and 130 is illustrated in FIG. 10. Both the

first and second jaws 120 and 130 include a generally flat face portion 125 and 135 respectively. A ridge 140

extends outwardly from the generally flat face portion

125 and 135. In lieu of the plurality of circular

sealing extensions, the second jaw 130 has a solid bar 145 extending outwardly from the generally flat face

portion 135 in a region disposed above the ridge 140.

To achieve the same goal of providing a seal that is

more easily opened at the opening end 90 than the closed end 95 of the gabled top, the solid bar 145 and the

ridges taper to a diminished degree of extension in the

regions 150 and 155.

Although the present invention has been described

with reference to specific embodiments, those of skill in the art will recognize that changes may be made

thereto without departing from the scope and spirit of the invention as set forth in the appended claims.