Package making – Progressively seamed cover web or web folds – With closing of web between package units
Reexamination Certificate
2002-02-01
2003-08-12
Sipos, John (Department: 3721)
Package making
Progressively seamed cover web or web folds
With closing of web between package units
C053S552000, C053S374600, C053S375400
Reexamination Certificate
active
06604343
ABSTRACT:
BACKGROUND OF THE INVENTION
A. Field of the Invention
The present invention relates to a latitudinal sealing mechanism for use in a bag-packaging machine. More specifically, the present invention relates to a latitudinal seal mechanism for use in a bag-packaging machine that fills articles to be packaged in a bag while packaging the bag by sealing tubular packaging material longitudinally and latitudinally. The present invention also relates to such bag-packaging machine.
B. Description of the Related Art
There has been a longitudinal bag-packaging machine that fills articles such as foods to be packaged in a bag while manufacturing and packaging the bag.
For instance, a longitudinal pillow packaging machine forms a packaging material which is a sheet-shaped film into tubular shape by using a former and a tube. Longitudinal seal means (heat sealing) seals longitudinal edges of the tubular packaging materials that are placed one on top of another, thereby making bags. The pillow packaging machine fills articles to be packaged into the tubular packaging materials through the tube. Latitudinal sealing mechanism below the tube seals the upper portion of a bag and the bottom portion of an following bag. Then the pillow packaging machine cuts the middle of the latitudinally sealed portion. In such pillow packaging machine, operations of making a bag and filling articles in the bag occur in a continuous manner.
An example of such bag packaging machine is disclosed in Japanese Laid-Open Patent Application 10-86910. In the packaging machine disclosed therein, the tubular packaging material is sealed latitudinally by heating and pressing a pair of seal portions called seal jaws against each other, with the pair of seal jaws opposing each other across the conveyance path of the tubular packaging material. In a structure where the seal jaws simply repeat linear back and forth movements, the packaging material is sealed only at a point (a line). Therefore, conveyance of the packaging material has to be stopped while the packaging material is being sealed in this structure. To avoid this problem, each seal jaw is controlled by two kinds of motors, such that each seal jaw moves drawing a locus that is in the shape of letter D. In this way, enough sealing time is secured while conveying the tubular packaging material continuously, by having the seal jaws follow the tubular packaging material. Motors used in this bag packaging machine for controlling each sealing jaw include, a rotational motor for rotating each seal jaw, and a horizontal motor for moving each seal jaw horizontally back and forth.
Some of such mechanisms utilize a cam having a groove formed thereon, so as to engage inner and outer sides of a cam follower. U.S. Pat. No. 5,031,386 discloses one of such mechanisms. In this mechanism, a cam follower that supports a seal jaw engages a cam having a groove that is formed in the shape of the letter D. The cam follower and the seal jaw are supported by an end of a drive member fixed to a shaft. As the shaft rotates, the cam follower and the seal jaw move along the groove on the cam. In this manner, the seal jaw moves drawing a locus in the shape of letter D.
Problem to be Solved by the Invention
Although the aforementioned mechanism allows the seal jaw to move drawing a locus in the shape of letter D, the seal jaw and the cam follower need to be able to slide against the drive member, since the seal jaw moves drawing a locus in the letter of D instead of a circle while the drive member rotates.
However, it is structurally difficult to configure a sliding mechanism having bearings in the portion where sliding needs to occur. Consequently, the seal jaw and the cam follower have to slide against the drive member by contacting and slipping against the drive member. Furthermore, if multiple cam followers are coupled to the cam to increase the processing speed of the bag packaging machine, the mechanism is subject to even more strict space constraint. Also, as the processing speed of the bag packaging machine increases, the slip-sliding by the cam follower and the seal jaw against the drive member may lead to a durability problem of the latitudinal sealing mechanism.
Further, packaging materials are becoming thinner recently. Accordingly, more pressure is required to seal the packaging material. This causes a greater reactionary force in the structure that supports each seal jaw. Especially in the structure disclosed in the aforementioned applications, reactionary force occurs in the horizontal motor that moves each seal jaw horizontally back and forth. Consequently, the horizontal motor has to be able to generate a torque that is large enough to be able to oppose the reactionary force. In other words, the horizontal motor is required of extra functions that would not be necessary if the horizontal motor were simply moving seal jaws horizontally. Also, the rotational motor has to rotate each seal jaw (in a downward direction) pushing the seal jaw against the reactionary force applied to each seal jaw. Therefore, the rotational motor also needs to be able to generate torque that is comparable to the torque of the horizontal motor.
In the structure where two kinds of motors rotate each seal jaw so as to draw a locus in the shape of letter D and thereby generate sealing pressure, the magnitude of sealing pressure can be easily adjusted by adjusting the horizontal motor. On the other hand, such structure requires a high-powered motor that can generate torque comparable with the sealing pressure, which leads to a higher cost of the bag packaging machine.
In view of the above, there exists a need for an improved latitudinal seal mechanism for a bag packaging machine which overcomes the above mentioned problems in the prior art. This invention addresses this need in the prior art as well as other needs, which will become apparent to those skilled in the art from this disclosure.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a latitudinal seal mechanism for use in a bag packaging machine that utilizes a cam, with the latitudinal seal mechanism allowing a seal portion to move drawing a locus in a shape other than a near circle having the shape of the letter D, without utilizing a structure in which the cam follower and the seal portion (seal jaw) slide against a coupling member (drive member) fixed to a rotational shaft (shaft).
In accordance with one aspect of the present invention, there is a latitudinal seal mechanism for use in a bag packaging mechanism that fills articles to be packaged while sealing a tubular packaging material in longitudinal and latitudinal directions. The latitudinal sealing mechanism includes a seal portion, a fixed cam, a cam follower, a rotational shaft, a coupling member, and a shaft support portion. The seal portion is adapted to be heated and move circularly, such that the seal portion abuts on and moves away from the tubular packaging material. The fixed cam has a shape that corresponds to a locus of the movement of the seal portion. The cam follower supports the seal portion and is adapted to move along the fixed cam. The rotational shaft relatively moves the cam follower circularly about a rotational center of the rotational shaft. The coupling member couples the rotational shaft and the cam follower. The shaft support portion supports the rotational shaft such that the rotational shaft can move in a direction that crosses with a direction of an axial core of the rotational shaft.
The latitudinal seal mechanism moves the heated seal portion circularly, such that the seal portion seals the tubular packaging material by heat when the seal portion abuts on the tubular packaging material. The fixed cam has a shape that corresponds to the locus of the movement of the seal portion such that sealing conditions such as sealing time are satisfied. The sealing portion is supported by the cam follower which moves along the fixed cam. The cam follower moves drawing a predetermined locus, thereby sealing the tubular packaging material.
The cam follo
Ishida Co. Ltd.
Shinjyu Global IP Counselors, LLP
Sipos John
LandOfFree
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