Adhesive bonding and miscellaneous chemical manufacture – Surface bonding means and/or assembly means therefor – With separate heating means for work
Reexamination Certificate
1998-11-02
2001-02-13
Sells, James (Department: 1734)
Adhesive bonding and miscellaneous chemical manufacture
Surface bonding means and/or assembly means therefor
With separate heating means for work
C156S544000, C156S555000, C156S579000
Reexamination Certificate
active
06186210
ABSTRACT:
The invention concerns a heat-sealing device for overlapping heat-sealing of film edges, having pressure rollers, for pressing the film edges together after they are heated, which sit on shafts of which at least one is movably guided in the direction of the other shaft and vice versa.
Heat-sealing devices of the kind described above are used in particular for heat-sealing of films in landfill construction. The purpose of the films is to seal the base of the landfill. In this context, stringent demands are made on the quality of the seal.
A heat-sealing device of this kind is known, for example, from DE 40 000 017 A1 and from DE 296 20 216.9. It has an infeed side over which the overlapping film edges are fed in one above another as the heat-sealing device is displaced, and are guided over a wedge-shaped heating element. This heating element is arranged horizontally, i.e. the two wedge surfaces which simultaneously also constitute the heating surfaces are located one above another. The heating element is oriented with its blunt end toward the infeed side. The top film edge is guided over the upper heating surface, and the bottom film edge over the lower heating surface. The two heating surfaces come together toward the discharge side in a linear wedge tip.
Pressure rollers lying one above another, which sit on shafts which extend horizontally and transverse to the defined passthrough direction of the film edges, are located directly behind the heating element. The film edges, heated and plasticized on the sides facing one another, are passed through between the pressure rollers and thereby pressed against one another in such a way that the plasticized surfaces melt into one another, and a heat-sealed join results after cooling.
The pressure rollers can be mounted in freely rotatable fashion on the shafts, or can rotate along with the shafts. In the latter case, there exists the possibility of driving one of the shafts, or even both of the shafts with the pressure rollers located thereon, in motorized fashion. In this case the pressure rollers also serve as feed rollers, i.e. they pull the film edges into the heat-sealing device and—since the film edges are usually designed to be stationary and thus are immovable—thus cause the heat-sealing device to be fed forward.
In the known heat-sealing devices, one of the shafts is usually mounted immovably on the unit and the other shaft is guided movably relative to the one shaft. Guidance occurs via one or two pivot arms, the pivot arms in the latter case running parallel to one another and being pivotable independently of one another. The shaft extends between the pivot arms, the pivot arm being movable, with the aid of an actuation device, toward and away from the other shaft.
Although the applied pressure acting between the pressure rollers can be adjusted, the heat-seal quality has occasionally not been satisfactory. Quality problems have occurred in particular when two heat-sealed seams were provided in order to form a testing channel between them, i.e. the heat-sealed seam have proven not to be sufficiently tight.
It is the object of the invention to configure a heat-sealing device of the kind cited initially in such a way that heat-sealed seams can be produced with greater reliability and quality.
According to the invention, this object is achieved in that at least one of the shafts can be aligned, via an adjustment device, parallel to the other shaft, and can be secured in that position.
This idea is based on the recognition, already part of the invention, that the position of the shafts carrying the pressure rollers has a substantial influence on the quality of the heat-sealed seam or seams. Even minor deviations from parallelism of the shafts means that the inherently provided width of the heat-sealed seam, and thus its strength, are not achieved. When two heat-sealed seams located spaced apart next to one another are being generated, lack of parallelism of the shafts can result in incomplete formation of one of the two heat-sealed seams. With the aid of the adjustment device according to the present invention, it is possible to set the two shafts exactly parallel to one another. This can advantageously be done in such a way that the pressure rollers are pressed toward one another with the aid of the actuation device, and then the one shaft is displaced by means of the adjustment device until the pressure rollers are in linear contact over their entire width. This can be checked, for example, with the aid of a piece of paper passed through the pressure rollers.
It has been found that adjustment of the shafts with the goal of setting them exactly parallel to one another results in perfect and reproducible heat-sealed seams. One reason for quality problems in the heat-sealed seams has thus been eliminated.
In a development of the invention, provision is made for the adjustment device to be associated with the movably guided shaft. Of course the adjustment device can also be arranged on the shaft mounted immovably on the unit, or both shafts can also be equipped with adjustment devices, although this is complex.
If the shaft is suspended at both ends, which is generally the case, there exists the possibility of providing the adjustment device in the region of one of the two shaft ends, so that this shaft end can be secured displaceably to the suspension mount there and its angular position can thereby be influenced. If the shaft is retained on two pivot arms, the adjustment device can be configured so that it connects the two pivot arms to one another and thus synchronizes their movement in such a way that the shaft extending between them runs exactly parallel to the shaft mounted immovably on the unit. In this case the adjustment device is advantageously configured as a bridge between the pivot arms which is attached detachably at least to one of the pivot arms, the attachment being displaceable. The attachment can, for example, be configured as a screw attachment. After loosening of the screws, the pivot arms can be set with respect to one another in such a way that the shaft retained by them ends up parallel to the other shaft. The screws can then be tightened again, and the position attained can thus be secured. The pivot arms can be joined to one another in such a way that the shaft guided by them runs parallel to the other.
REFERENCES:
patent: 4447288 (1984-05-01), Seaman
patent: 4744855 (1988-05-01), Ellenberger et al.
patent: 4923558 (1990-05-01), Ellenberger et al.
patent: 3443914 (1986-06-01), None
patent: 4000017 (1991-07-01), None
patent: 9110488 (1992-01-01), None
patent: 9110487 (1992-01-01), None
patent: 9114932 (1992-03-01), None
patent: 296 20 216 U (1997-04-01), None
Liniak, Berenato, Longacre & White LLC
Sells James
Wegener GmbH
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