Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1999-05-24
2001-11-13
Ball, Michael W. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S229000, C156S258000, C156S293000, C156S308400
Reexamination Certificate
active
06315849
ABSTRACT:
TECHNICAL FIELD
This invention relates to methods of joining flexible sheets to tubes.
BACKGROUND OF THE INVENTION
There are many articles of manufacture that have plastic tubes joined to flexible plastic sheets. For example, many products are packaged in plastic wrap which, because of the shapes of the products, dictate that the packages have tubular extensions. Other flexible containers are in the form of tubes with end flanges. Asbestos abatement containers fall in this category. For example, U.S. Pat. No. 4,852,687 illustrates a plastic enclosure for collecting asbestos as it is stripped from a ceiling. The enclosure has a funnel like enclosure from which a chute depends. Glove bags that are wrapped about asbestos clad pipes also have one or more tubes that depend from a shroud. Examples of these are shown in U.S. Pat. Nos. 5,553,933 and 5,632,846. Intravenous drip tubes used in medical facilities to meter fluids slowly into patients also have fitment tubes joined to pouches that are suspended from stands.
Plastic tubes can be and often are joined to plastic sheet materials with adhesives and with tapes. However, for speed and consistency, more often they are heat sealed which causes the plastics to fuse and provide a watertight or airtight joint. Heretofore this has commonly been done as shown in
FIGS. 1-5
of the drawing. A plastic tube
10
is inserted through a tubular mandrel or anvil
12
having an annular step
13
in one end as shown in FIG.
1
. An end of the tube is folded outwardly over the end of the mandrel as shown in
FIG. 2
to form an annular tube lip
14
. A plastic sheet
15
is positioned over the mandrel and tube lip as shown in
FIG. 4. A
sealing platen then presses the sheet against the tube lip
14
and the contiguous annular portion Of the tube that overlays the mandrel step. The platen is sometimes in the shape of a donut as shown at
17
in
FIG. 3
or other times it is a disc as shown at
18
in FIG.
4
. The sheet can have a precut hole or the hole can be formed in the sheet with an annular, electric cutting wire
19
affixed to the platen
18
as shown in FIG.
4
. The sheet is then fused to the tube lip with heat generated by unshown electric heating elements in the mandrel or platen. The bonded tube and sheet are then removed as shown in FIG.
5
.
A persistent problem with the just described method is that it produces pinholes in the seal that cause capillary leaks. This is due to the fact that the stretching of the tube end over the mandrel causes it to gather and wrinkle as indicated in
FIGS. 2-4
. Once these wrinkles are pressed against the flat sheet, radiating capillary channels are formed as the two layers are sealed.
Accordingly, it is seen that a need has long existed for a method of joining a plastic tube to a flexible plastic sheet in a manner that provides an air impervious annular seal that is substantially free of capillary leaks. It is to the provision of such therefore that the present invention is primarily directed.
SUMMARY OF THE INVENTION
In a preferred form of the invention, a plastic tube is joined to a flexible plastic sheet by mounting an end of the tube over a mandrel of a given size. A hole is cut in the sheet of a size less than the mandrel. The sheet is stretched over the mandrel bringing a portion of the sheet about the hole snugly over the tube end and mandrel. That portion of the sheet is then heat sealed to the tube end, and the joined sheet and tube removed from the mandrel.
If the plastic tube is substantially rigid it need not be mounted to a mandrel. In that case the sheet is stretched directly over the tube.
REFERENCES:
patent: 4852687 (1989-08-01), Hittler
patent: 5553933 (1996-09-01), Ross
patent: 5632846 (1997-05-01), Ross
patent: 5827598 (1998-10-01), Larsen et al.
Baker, Donelson Bearman & Caldwell
Ball Michael W.
Grayling Industries, Inc.
Haran John T.
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