Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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METHOD FOR MAKING PIPE FITTING COVERINGS ~;
BAC~GROUND OF THE INVENTION ~
The present invention relates in general to ; r
improved pipe fitting covers and more particularly to an ~-
improved method for making said covers.
It is desirable, and often essential, that pipe -
i fittings such as elbows, tees, valves, flanges, return bends, ;~
Y branches, reducing fittings, strainers, unions, and
various other fittings, be provided with a suitable covering
~ 10 to protect them from the elements and/or surrounding
;~ contaminants. Conventionally, pipe fittings have been
~, covered by, for example, wrapping of the pipe fitting with
an adhesive tape, molding of a plastic material about the
fitting, or enclosing the fitting in a metal or plastic
multi-piece cover.
U. S. Patent No. 3,495,629 to Botsolas et al,
issued February 17, 1970, describes an alternative techni~ue
which involves the use of a one-piece cover molded from a
flexible, resilient material. The covering is formed from
a sheet of resilient, thermoplastic material which has a
shape conforming to the shape of the pipe fitting to be
covered and overlapping portions that may be held in place
by cementing.
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In an alternative embodiment, Botsolas et al
teaches that the covering may be preformed in a shape other `
than the final configuration and then bent or folded into the
final configuration during installation. To illustrate the
; 5 alternative embodiment, an elbow covering is described which
comprises a trough having parallel side walls with semi-
circular end pieces and a downwardly extending central
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portion. During installation, the downw~rdly extending
~; central portion is fitted over the convex portion of the
` 10 elbow and the end pieces are folded inwardly in overlapping
position over the concave portion of the elbow. ~
::t'~' While the one-piece cover described in the r~, "
, Botsolas et al alternative embodiment, and similar
;, commercially available covers are superior in some respects
to other prior art pipe fit*ing covers, they have proven in
practice to be difficult to hold in place while being
sealed about the pipe fitting since they tend to spring back
into the shape of the preform.
One-piece covers having the shape of the final
configuration, as taught by the preferred embodiment of `
Botsolas et al, are difficult and expensive to manufacture by
prior art techniques, such as that of forming of two pieces
which are then cemented toge*her or of molding in a
single step process the final configuration.
OBJECTS OF THE INVENTION
It is therefore an object of the present invention
to provide an improved method for making a one-piece pipe
fitting cover marketed in the shape of the final configuration.
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It is another object of the present invention
to provide an economical method for manufacturing pipe - .
fitting covers.
Still another object is to provide an economical
method for manufacturing one-piece pipe fitting covers from
a resilient, thermoplastic material in a two-stage process.
Those objects are attained by the invention which
contemplates a method of forming a cover for a pipe
fitting having a complex configuration in the same complex
configuration as the pipe fitting to be covered, wherein
the cover includes an opening extending between the ends
of the cover whereby the cover may be spread apart and
placed in position surrounding the pipe fitting. The
method comprises the steps of forming a single piece of
thermoplastic material into a preform having an inter-
mediate non-planar configuration different from the
complex configuration of the fitting to be covered,
folding the preform into the final complex configuration
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of the fitting to be covered, heating the material while
retaining it in its final complex configuration, and cooling
the material to set it in its final complex configuration
while retaining the material in its final complex config-
uration.
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Other objects of the present invention, i not
specifically set forth herein, will be obvious to the skilled
artisan from a reading of the detailed description of the
invention taken in conjunction with the drawings.
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BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective view illustratin~
; elbow joint cover made in accordance with the present
invention, r '
; Figures 2 and 3 are perspective views illustrating
- 10 preforms useful in making the elbow cover shown in Figure l;
Figure 4 illustrates a Tee cover made in accordance
:~ with the present invention; and ~:
., Figure 5 illustrates a preform useful in making the
Tee cover shown in Figure 4.
DETAILED DESCRIPTION OF THE INVENTION
In accordance with the present invention, an
improved complex tubular shaped pipe fitting cover is made
by forming from resilient, thermoplastic polymeric sheet
material a non-tubular preform which is so shaped that it
may be folded or bent about a pipe fitting of complex tubular
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configuration such as an elbow to assume the desired
final configuration of the cover, as described in Botsolas
et al Patent 3,495,629. Next, according to the present
invention, the preform is folded into the desired final
complex tubular configuration corresponding to the complex
tubular conf,iguration of the pipe fitting it is intended to
cover, and the preform is heated to above the softening
temperature of the thermoplastic material while the preform
is maintained in the final configuration. Finally, the
preform is cooled below the softening temperature of -
the thermoplastic material while the preform is maintained
in the final complex tubular configuration.
The preform used in the present method may be
prepared from a thermoplastic polymeric material by one of
several conventional techniques including, but not limited to,
compression molding, injection molding, blow molding or
vacuum molding. In compression or injection molding, a
quantity of molten thermoplastic polymer is forced to take
the configuration of a mold cavity conforming to the shape
of the preform. In blow molding or vacuum molding, a softened -
sheet of thermoplastic polymer is blown or drawn against
a surface having the shape of the preform.
In describing the invention in greater detail,
specific reference will be made to the method for making
elbow joint and T-joint covers, although it is to be
realized that the description of these particular covers is
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intended only as illustrative of the invention, the ;~
manufacture of other covers in accordance with the present
method being obvious to one skilled in the art from an ~-
understanding of the method for ma~ing an elbow joint or `
T- j oint cover.
Elbow joint covers of the type illustrated in
Figure 1, are preferably formed by first fabricating from ~-
a sheet of resilient thermoplastic polymeric material a
complex non-tubular preform having the cGnfiguration shown
in Figure 2, which preform comprises a central domed portion
10 having a pair of integral flaps 12 spaced opposite each
other across domed portion 10 and extending outwardly from
the side walls thereof. Flaps 12 preferably have a semi-
elliptical cross-section and are substantially axially
aligned. The profile o domed portion 10 along a direction
transverse to the axis of alignment of flaps 12 preferably
approximates that of the elbow joint to be covered.
A complex non-tubular preform of the type shown
in Figure 3 and illustrated at Figure 6 in U. S. Patent No.
3,495,629 may also be used to form a complex tubular elbow
joint cover before being positioned about an elbow pipe
coupling. This preform is formed from a resilient sheet of
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thermoplastic material shaped into an elongated trough
having generally straight, longitudinal edqes 14 and ends 16
which are open-ended and preferably approximate a semi-
circular or parabolic section. Centrally located in the
trough is a central domed portion 18 which is expanded out-
wardly in a direction away from the longitudinal edges 14.
,. ..... .. .. .....
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Domed portion 18 is preferably expanded so as to have a
sinusoidal profile. Between domed portion 18 and ends 16
are flaps 20 which are subsequently folded toward each other
over domed portion 18. Flaps 20 correspond to flaps 12 of
the previously described preferred preform.
To form a T-joint cover as illustrated in Figure 4,
a preform of the type show~ in Figure 5 may be employed. This
preform comprises an arcuate-shapéd first trough 22 having
parallel side edges 24. The arc of trough 22 extends at
least 180 and preferably slightly greater than 180 to
provide an overlapping hem or marginal portion in the final
configuration. The cross-sectional radius is at least equal
to twice the radius of the pipe forming the crossbar of the
Tee to be covered.
Transecting first troug~. 22 at approximately its
central portion is a second trough 26 having parallel side
edges 28 adjoining and intersecting side edges 24 of first
trough 22. Second trough 26 also has an arcuate cross-
section of at least 180. The cross-sectional radius of second
trough 26 is at least equal to the radius of the upright of
the Tee to be covered, and preferably is slightly greater.
In practicing the present method, one of the preforms
fabricated according to the first stage of the process des-
cribed above is then folded, preferably about a suitable
support surface such as a mandrel or the like, corresponding
in shape to the fitting or coupling to be covered, or in a
correspondingly shaped mold, with the flaps being turned
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inwardly into contact with each other, and preferably into
overlapping position. The preform is then clamped or
otherwise held in place for the heating step as described
hereinafter.
The preform is then heated to such a temperature
to soften the thermoplastic material sufficiently to relieve
the stresses therein and reform the preform while the preform
is maintained in the complex tubular configuration. Heating
may be by way of radiant heat, immersion of the preform
into a heated water bath, heating of the support piece, or
the like. The actual heating conditions will vary depending
upon the polymeric material used and the thickness of the
preform. For example, a polyvinyl chloride preform having
a thickness of 15-30 mils is preferably heated to a temperature
of 175-200F. for at least 12-15 seconds.
After heating, the preform is maintained in its
complex tubular configuration while cooling it to below the
softening temperature of the polymer, and preferably to room
temperature. An external cooling medium such as a cooling
air or liquid may be applied in order to more rapidly reduce
the temperature.
After the thermoplastic material has been cooled to
at least below the softening temperature of the polymer,
it is to be observed that the complex non-tubular preform
has been transformed to a cover which will retain the final
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configuration corresponding to the complex tubular fitting -
or coupling with which it is to be used and, if the flaps
are spread apart and then released, the cover will immediately
return to that final configuration. ~;
The preform can be made from a variety of thermo~
plastic, polymeric materials including, but not limited to
vinyl resins, e.g., polyvinyl chloride; polypropylene;
polyethylene; acrylics; cellulose ethers and esters; and -
polyamides.
Normally, the preform and resultant covering
will preferably have a maximum thickness of from about 15 to 30
mils.
If desired, the insulating properties of the pipe
fitting covering may be enhanced by positioning an insulaticn
material inside the preform and folding the preform over the
insulation. The insulation may be permanently adhered to the
inside of the pipe fitting cover by coating the insulation or
interior of the preform with an adhesive prior to positioning
of the insulating materiai.
In utilizing the covers prepared in accordance with
the present invention, the side flaps are pulled apart and
the cover is slipped over the pipe fitting. The flaps are
then released, whereupon the cover takes on the final
configuration. The side flaps are then-adhered to each other
by way of, for example, a suitable adhesive, sealing tape, or
by heat sealing.
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It is to be understood that many modifications and :~
variations of the present invention may be made without
departing from the spirit and scope thereof.
