U.S. patent number 3,677,684 [Application Number 04/884,901] was granted by the patent office on 1972-07-18 for apparatus for enlarging an extremity of a plastic pipe.
This patent grant is currently assigned to National Distillers and Chemical Corporation. Invention is credited to Gerald M. Platz.
United States Patent |
3,677,684 |
Platz |
July 18, 1972 |
APPARATUS FOR ENLARGING AN EXTREMITY OF A PLASTIC PIPE
Abstract
This invention is directed to apparatus for enlarging or belling
an extremity of a plastic pipe so that the extremity of an adjacent
length of pipe may be received and retained therein. An expanding
mandrel is provided, and this mandrel includes expander jaws,
expander wedges, and expander wedge guides which engage a tapered
spindle. A continuous steel sheath surrounds the mandrel components
and longitudinal movement of the tapered spindle provides
progressive enlargement or reduction of the mandrel diameter.
Inventors: |
Platz; Gerald M. (Champaign,
IL) |
Assignee: |
National Distillers and Chemical
Corporation (New York, NY)
|
Family
ID: |
25385669 |
Appl.
No.: |
04/884,901 |
Filed: |
December 15, 1969 |
Current U.S.
Class: |
425/393; 425/469;
425/DIG.218 |
Current CPC
Class: |
B29C
57/04 (20130101); Y10S 425/218 (20130101) |
Current International
Class: |
B29C
57/04 (20060101); B29C 57/00 (20060101); B29c
017/00 () |
Field of
Search: |
;18/19TE,19TM,DIG.14,DIG.5,45R,45T ;72/393,178,392,399,452
;249/178-180,184,186,151-153 ;25/128K,128R |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Flint, Jr.; J. Howard
Claims
What is claimed is:
1. An expanding mandrel assembly comprising, in combination, a
plurality of radially disposed expander jaws and a plurality of
expander wedges, said expander wedges being located alternately
with respect to said expander jaws, each of said expander jaws
including an arcuate outer wall surface and angularly disposed
converging inner wall surfaces and each of said expander wedges
including an arcuate outer wall surface having a radius
complementary to that of the expander jaws and angularly disposed
diverging side walls having an angular relationship complementary
to that of the converging inner surfaces of the expander jaws;
a radially disposed wedge guide associated with each expander
wedge, the base of each expander wedge being provided with a
longitudinally disposed T-shaped slot for the reception of the
complementarily conformed upper extremity of the associated wedge
guide;
each of said expander jaws and expander wedges being provided with
a circumferential notch adjacent at least one extremity thereof and
a continuous coil spring received within said aligned
circumferential notches to bias said expander jaws and wedges
toward each other;
cam means located axially of said mandrel assembly and movable
laterally to increase selectively the diameter of said mandrel,
said cam means being constituted by a tapered spindle and each
wedge guide having a complementarily tapered inner surface which
engages said spindle, the peripheral surface of said spindle being
provided with a plurality of longitudinally disposed and uniformly
spaced wedge guide receiving slots within which the lower
extremities of said wedge guides are slidably received; expansible
spring means surrounding said mandrel assembly, said spring means
being operative to urge said expander jaws and expander wedges
inwardly toward a retracted position; and
inner and outer flanged end caps for said mandrel and spindle
assembly, said inner end cap including a vertically disposed wall
having a centrally located aperture to permit ready passage
therethrough of the axially located cam means, said outer end cap
being mounted upon the outer extremity of said cam means and
engaging with the outer extremity of said mandrel assembly in
surrounding relationship when said cam means approaches the limit
of its movement in the expanding direction.
2. An expanding mandrel as set forth in claim 1 where the
vertically disposed wall of the inner end cap is provided with a
plurality of radially spaced T-shaped slots and the inner extremity
of each wedge guide has a complementarily shaped vertical extremity
receivable within an associated slot whereby said wedge guides are
secured to said inner end cap.
3. Apparatus for enlarging an extremity of a length of a plastic
pipe so that the extremity of an adjacent length of plastic pipe
may be received and retained therein, said apparatus including a
mounting plate, a bracket including an internally threaded
handwheel mounted on one face of said mounting plate, and a
horizontally disposed threaded adjusting rod extending through said
bracket and mounting plate;
an expanding mandrel assembly comprising, in combination, a
plurality of radially disposed expander jaws and a plurality of
expander wedges, said expander wedges being located alternately
with respect to said expander jaws, each of said expander jaws
including an arcuate outer wall surface and angularly disposed
converging inner wall surfaces and each of said expander wedges
including an arcuate outer wall surface having a radius
complementary to that of the expander jaws and angularly disposed
diverging side walls having an angular relationship complementary
to that of the converging inner surfaces of the expander jaws;
a radially disposed wedge guide associated with each expander
wedge, the base of each expander wedge being provided with a
longitudinally disposed T-shaped slot for the reception of the
complementarily conformed upper extremity of the associated wedge
guide;
each of said expander jaws and expander wedges being provided with
a circumferential notch adjacent at least one extremity thereof and
a continuous coil spring received within said aligned
circumferential notches to bias said expander jaws and wedges
toward each other;
cam means located axially of said mandrel assembly and movable
laterally to increase selectively the diameter of said mandrel,
said cam means being constituted by a tapered spindle mounted upon
the inner extremity of said threaded adjusting rod and each wedge
guide having a complementarily tapered inner surface which engages
said spindle, the peripheral surface of said spindle being provided
with a plurality of longitudinally disposed and uniformly spaced
wedge guide receiving slots within which the lower extremities of
said wedge guides are slidably received; expansible spring means
surrounding said mandrel assembly, said spring means being
operative to urge said expander jaws and expander wedges inwardly
toward a retracted position; and
inner and outer flanged end caps for said mandrel and spindle
assembly, said inner end cap including a vertically disposed wall
having a centrally located aperture to permit ready passage
therethrough of the axially located cam means, said outer end cap
being mounted upon the outer extremity of said cam means and
engaging with the outer extremity of said mandrel assembly in
surrounding relationship when said cam means approaches the limit
of its movement in the expanding direction.
4. Apparatus as set forth in claim 3 where said adjustable mandrel
includes an inner flanged end cap having a centrally located
aperture through which the spindle extends, means being provided to
secure said inner flanged end cap to said mounting plate in spaced
relation with respect thereto the spacing between said mounting
plate and inner end cap being sufficiently great to receive that
portion of the spindle which passes through the mandrel when the
limit of enlargement will be reached.
5. An expanding mandrel as set forth in claim 1 where the
expansible spring means surrounding said mandrel assembly is a
stainless steel spring sheath having overlapping edges and
adjustable with said mandrel to provide a smooth peripheral surface
for at least a portion of the length of said expander jaws.
6. Apparatus for enlarging an extremity of a length of plastic pipe
as set forth in claim 3 where the expansible spring means
surrounding said mandrel assembly is a stainless steel spring
sheath having overlapping edges and adjustable with said mandrel to
provide a smooth peripheral surface for at least a portion of the
length of said expander jaws.
Description
This invention relates to apparatus for expanding or enlarging an
extremity of a length of flexible tubing or pipe to permit the
ready assembly of an adjacent length of such tubing or pipe. The
piping or tubing with which we here are concerned may be produced
by extrusion or related processes from such polyolefins as
polyethylene, polypropylene, polybutene, and the like, and are well
known in this art.
Difficulties have been experienced in connection with the joining
together of adjacent lengths of such pipe or tubing and prior art
practices which include the use of fusing operations, solvents, and
adhesives, have proven unsatisfactory. One particularly efficient
method for accomplishing the results desired is through the
enlargement, as by a belling operation, of one extremity of a pipe
length to an internal diameter complementary to the external
diameter of the adjacent pipe length, which then may be received
telescopically within said enlarged extremity.
Accordingly, it is a major object of the present invention to
provide novel apparatus for the ready expansion or enlargement of
an extremity of a flexible pipe produced from plastic material
whereby the extremity of an adjacent pipe length may be received
and retained therein with particular convenience.
It is a further object of the invention to provide a device of the
class set forth which may be utilized with pipe lengths of varying
interior diameters and will be adjustable from an inoperative to an
operative position, to fit within a pipe length and then be
expanded to enlarge the extremity of said pipe length to the
diameter or extent required.
It is still a further object of the present invention to provide a
novel method for joining adjacent lengths of flexible plastic pipe
by enlarging or belling an extremity of one length of such pipe to
an interior diameter complementary to the exterior diameter of the
next adjacent length of pipe which then may be received and
securely retained within said enlarged extremity.
Briefly stated, the invention comprises the utilization of an
expanding mandrel including a plurality of jaws or segments which
are slidably associated with a conical spindle, these jaws being
surrounded by an encompassing spring steel sheath to provide a
smooth peripheral surface. Lateral movement of the spindle in one
direction with respect to the jaws will result in the opening of
the jaws from a retracted to an operative position, thereby
increasing the diameter of the spring steel sheath and enlarging
the interior diameter of the extremity of a length of plastic pipe
within which the mandrel has been positioned. It will be understood
that the gap between adjacent segments or jaws will be increased in
direct relationship to the extent of movement of the segments upon
the spindle, and is a function of the number of jaws and/or the
expansion ratio. However, these gaps are bridged by the spring
steel sheath which increases in diameter as the jaws open and, at
all times, provides a smooth and continuous peripheral surface
which contacts the interior surface of the plastic pipe being
enlarged.
Further objects and advantages of the invention will be readily
apparent from the accompanying drawings and following description
wherein:
FIG. 1 is a side elevational view of a novel pipe enlarging or
expanding tool or apparatus constructed in accordance with the
present invention;
FIG. 2 is a longitudinal sectional view, on an enlarged scale,
taken on the line 2--2 of FIG. 3 through the novel expanding
mandrel, parts being broken away, the adjustable jaws being in
expanded or operative position;
FIG. 3 is a transverse sectional view through the expanding
mandrel, taken on the line 3--3 of FIG. 1 and also illustrating the
jaws in expanded position;
FIG. 4 is a transverse sectional view through the expanding
mandrel, similar to FIG. 3 and illustrating the jaws in fully
retracted position;
FIG. 5 is a side elevational view of the expanding mandrel and
spindle in retracted or inoperative position illustrating, in
section, the extremity of a length of plastic pipe positioned
thereupon;
FIG. 6 is a side elevational view, similar to FIG. 6, and
illustrating the spindle in operative position with the expanding
mandrel enlarged and the interior diameter of the length of plastic
pipe having been increased so as to be complementary to the
exterior diameter of the adjacent pipe length to be connected
thereto;
FIG. 7 is a side elevational view of the operative spindle per
se;
FIG. 8 is a transverse sectional view through the expanding mandrel
taken on the line 8--8 of FIG. 2 and looking in the direction of
the arrows;
FIG. 9 is a detail sectional view taken on the line 9--9 of FIG.
8;
FIG. 10 is a perspective view of an expanding guide which provides
operative association between each expanding wedge of the mandrel
and the spindle;
FIG. 11 is a perspective view of the preferred form of expander
wedge employed; and
FIG. 12 is a perspective view of one of the expander jaws.
As shown in the drawings, the novel apparatus of the present
invention includes a stand or base portion 10 including a
vertically disposed mounting plate 11, secured to standards or the
like 12, a spindle supporting U-shaped bracket 13 being attached to
one face of the mounting plate by any suitable means such as bolts
or the like 13a.
An internally threaded adjusting element or hand wheel 14 having a
hub portion 14a is rotatably received within a suitable aperture in
the bracket 13 and a longitudinally disposed threaded adjusting rod
15 extends through said handwheel and projects through the mounting
plate 11 which carries a tubular guide 11a through which the
adjusting rod 15 passes. A conical and outwardly tapered spindle or
expander 16 is mounted upon the reduced extremity 15a of the
adjusting rod 15, the peripheral surface of said spindle being
provided with a plurality of uniformly spaced expander guide
receiving slots 16a or cam surfaces (six such slots being
illustrated) for a purpose to be described more fully hereafter. It
will obvious that rotation of the handwheel 14 in one direction
(clockwise) will advance the adjusting rod 15 and the spindle or
expander 16 in a direction away from the mounting plate 11 and that
rotation of the handwheel in the opposite direction
(counter-clockwise) will move the adjusting rod and the spindle
toward the mounting plate 11.
The novel expanding mandrel of the present invention, as shown more
particularly in FIGS. 2 through 6 of the drawings, is constituted
by a plurality of expander jaws 17 and a similar number of expander
wedges 18, each of said expander wedges being mounted upon the
outer extremity of an expander wedge guide 19, the inner extremity
of each wedge guide being received within a slot 16a provided in
the peripheral surface of the spindle 16. These slots are uniformly
spaced and provide an assembled relationship whereby the expander
wedges are radially mounted upon said spindle, there being an
expander wedge between adjacent expander jaws.
In the embodiment of the invention illustrated, six expander jaws
17 and an identical number of expander wedges and wedge guides are
disclosed; however, a greater or lesser number can be utilized with
equal facility, it being understood that the greater the number of
jaws, the smaller the gap or span therebetween.
Each longitudinally disposed expander jaw 17 is preferably of
substantially triangular cross-sectional configuration, including
an arcuate outer wall surface 17a and angularly disposed converging
inner wall surfaces 17b with a flattened base 17c therebetween. The
curvature or radius of the outer wall surface should be lesser than
the minimum interior diameter of the plastic pipe to be worked upon
whereby the expanding mandrel, when in retracted position, may be
received readily within such plastic pipe. Desirably the outer
arcuate surface of each expander jaw is stepped down from its inner
end to its outer end, as shown at 17d, to assist in the insertion
of the mandrel within a pipe extremity.
Each expander wedge 18 includes an arcuate outer longitudinal
surface 18a, having a curvature complementary to that of the
expander jaws, angularly disposed and diverging side walls 18b, the
angular relationship thereof being complementary to that of the
converging inner wall surfaces of the expander jaws, and a
flattened base portion 18c. Each expander wedge 18 is provided with
a T-shaped longitudinally disposed and centrally located slot or
keyway 18d which extends the full length thereof and within which
the complementary T-shaped head 19a of a wedge guide 19 is
received, the association being such that the wedge guides 19 may
reciprocate freely within the slots 16a in the spindle 16 as the
expanding mandrel is adjusted from retracted to expanded position
and vice versa.
As shown more particularly in FIG. 10 of the drawings, each
expander wedge guide 19 is provided with a T-shaped head portion
19a and a tapered bottom edge 19b whereby the height of each wedge
guide decreases from the inner to the outer end thereof, the rate
of decrease being complementary to the taper of the spindle 16.
Thus, when a wedge guide 19 is received with a slot 16a, the outer
surface of the wedge guide, and the expander wedge supported
thereupon, will at all times lie in a plane parallel to the
longitudinal axis of the spindle.
With the spindle, wedge guides, expander wedges, and expander jaws
in assembled relationship as described hereabove, suitable means is
provided for maintaining the assembly against inadvertent
separation, and a preferred form of such means includes an inner
flanged end cap 20 mounted in fixed spaced relationship with
respect to the standard 12 and an outer flanged end cap 21, which
is mounted upon and movable with the reduced outer extremity of the
expander 16, as shown more particularly in FIG. 2 of the drawings,
the expander jaws 17 and expander wedges 18 being of a length to
fit snugly therebetween.
Desirably, the peripheral surfaces of the expander jaws, wedges and
wedge guides are circumferentially notched or recessed adjacent
each extremity for the reception of a continuous coil spring or the
like 22 whereby the several elements are urged inwardly toward each
other and the spindle upon which these components are
supported.
As shown more particularly in FIG. 1 of the drawings, the mandrel
assembly is mounted in fixed relationship with respect to the
mounting plate 11, suitable securing means, such as bolts or the
like 23, having one end attached to the inner end cap 20 as shown
at 23a and the other end secured to the mounting plate 11 as shown
at 23b being provided. It will be noted that the spacing between
the expanding mandrel and the mounting plate 11 must be
sufficiently great to receive that portion of the spindle which
passes through the mandrel when the limit of expansion or
enlargement will be approached.
To provide a more certain assembly between the expander wedges and
wedge guides and the inner end cap 20, each wedge guide 19
terminates at its inner extremity in a vertically disposed T-shaped
head portion 19c and the adjacent face or wall of the end cap 20 is
provided with a plurality of radially spaced and complementary
T-shaped slots 20a within which the head portions 19c of the wedge
guides are received.
To provide a continuous and smooth peripheral surface for the
expander jaws 17 which will be spread apart and thus have an
increasing gap between adjacent jaws as the operative diameter of
the mandrel is enlarged, a stainless steel spring sheath 24 is
provided. This sheath, which will have a longitudinal dimension in
accordance with the width of enlarged pipe extremity desired,
viewed transversely, is spiral with well-overlapping edges and
under continual inherent spring tension to urge the expander jaws
into firm engagement with the expander wedges. As the diameter of
the mandrel is enlarged, the overlapping edges of the sheath will
skip over each other to permit simultaneous enlargement of the
sheath. In like manner, as the mandrel diameter is decreased,
inherent spring tension or resiliency insures simultaneous
reduction in sheath diameter.
This sheath, which is produced from particularly thin sheet
material, bridges the gap between adjacent expander jaws and
insures uniform enlargement of the extremity of the plastic pipe or
tubing and, if desired, the floating end or both edges 24a of the
sheath may be feathered or tapered to a knife edge to eliminate any
line on the interior surface of the enlarged pipe extremity.
The method of operation of the apparatus discussed in detail
hereabove is particularly simple and the steps required in
connection therewith are detailed as follows.
It is necessary that the plastic pipe extremity to be enlarged be
preheated to facilitate the expansion or enlargement thereof and a
suitable heating chamber (not shown) is provided for such purposes.
Such units are well-known in this and related arts and are
available on the open market as closed-loop circulating air blowers
with electrical finned heating elements. Temperature elevation on
the order of from 250.degree. to 400.degree. F. is adequate for
present purposes. Temperatures on the order of 500.degree. F. or
higher may blister the plastic pipe and are to be avoided. It has
been found in practice that with the heating chamber temperature
controlled at 400.degree. F. approximately 1 minute and 20 seconds
is required to preheat an 8-inch diameter plastic sewer pipe to a
temperature on the order of 250.degree. F, this constituting a soft
"bell forming" condition.
The preheated plastic pipe extremity 25 is then placed upon the
collapsed mandrel, as shown in FIG. 5 of the drawings. The spindle
16 is then moved toward the mounting plate 11, by means of rotation
of the handwheel 14, thereby moving the wedge guides 19 outwardly
as the upwardly inclined slot or cam tracks 16a slide beneath the
bottom edges of said wedge guides. This results in the increase in
diameter of the expanding mandrel and encompassing spring sheath,
preferably produced from stainless steel with a highly polished
exterior surface, with the resultant enlargement of the interior
diameter of the plastic pipe to create the belled portion 25a. The
expanded pipe extremity is then permitted to cool, the mandrel is
closed by moving the spindle in a direction toward the interior of
the pipe length and the expanded or belled pipe length, or sleeve,
is slipped off or removed from the mandrel.
The degree of enlargement is readily controllable as by a gauge or
other indicating media or stop means (not shown) on the apparatus
and, in each instance, should be complementary to the exterior
diameter of the pipe length to be received therein.
It has been found in practice that a thin sheath or sheet of
stainless steel surrounding or encompassing the mandrel or
enlarging die adequately bridges any unsupported sections or gaps
between the expander jaws. The highly polished surface of this
sheath forces the plastic material to slide or flow uniformly with
respect to the specific locations of the expander jaws and produces
equal enlargement or stretch around the entire surface of the
belled extremity resulting in uniform interior and exterior
surfaces of the belled portion without substantial gauge
variation.
There has been described novel apparatus and method for the
enlargement of an extremity of a length of plastic pipe which may
be utilized with particular convenience and economy and which
includes a novel expanding mandrel having wide-spread utility in
the industrial arts.
It will be obvious to those skilled in this art that various
changes may be made in the invention without departing from the
spirit and scope thereof and reference therefore is had to the
claims for summaries of the essentials of the invention and of the
novel features of construction and novel combinations of parts, and
method of operation, for all of which protection is desired.
* * * * *