Note: Descriptions are shown in the official language in which they were submitted.
.~ 8
APPAR~TUS FOR FORMING AN ANNULAR GROOV~ IN
_
THE END OF CAST CONCRETE PIPE
_
The invention pertains to the manufacture of concrete
pipe and more particularly to that phase thereof that in-
cludes the finishing of the ends of the pipe for ma~ing with
like sections when assembled, as for use in conducting fluids,
such as water in drainage systems and the like. Opposite ends
of the pipe are conventionally formed as male and female ends,
respectively, and, for the purpose of improving the connection
between the male end of one pipe and the female end of its
neignbor, resort has been had heretofore to the provision in
the male end of an annular groove into which an appropriate
seal is fitted during installation of the pipes end to end.
In the past, the groove has been formed by a header ring of
clam shell character, each half containing one-half of the
groove-forming ring, and the halves were selectively opened
and closed during and after the casting operation. It was
also known to oscillate the clam shell to improve the groove.
The present invention provides an improvement in the form-
ing of the groove in that the header ring is continuous and
the groove-forming ring is removable from the interior of the
header ring, so as to remain with the pipe and in the formed
groove whèn the header ring is removed during or after strip-
ping of the form from the cast pipe. The groove-forming ring
is split in its circumference so as to be capable of being
"sprung" for ultimate removal from the groove. The header
and groove-forming ring are rotated in unison by a header rotor
and drive mechanism therefor. It is a further feature that the
rotor is connected to a pressure head for vertical movement
toward and away from the pipe section in process. rrhe rotor
has an annular row of teeth by means of which the rotor may
be sprocket-driven by a small motor, the rotation being uni-
directional and preferably at least a full revolution so as
to completely trowel the groove in the pipe end.
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In the Drawings:
Fig. 1 is an elevation, with parts omitted and partly in
cross section to better illustrate the construction.
FigO 2 is a plan as seen generally along the line 2-2 of
Fig. 1.
Fig. 3 is a bottom view of the rotor for turning the tongue
trowel.
Fig. 4 is an enlarged edge view of the chain drive for the
rotor.
Fig. 5 is an enlarged fragmentary section showing how the
chain is affixed to the rotor.
Fig. 6 is an elevation as seen along the line 6-6 of Fig. 5.
Fig. 7 is a fragmentar~ view showing the motor~sprocket-
chain drive for the rotor.
Fig. 8 is an enlarged fragmentary sectional view showing
the header ring and its groove-forming ring.
Fig. 9 is a reduced plan of the snap ring ~or the top header
ring.
-- 3 --
In Fig. l, the numeral 10 designates a floor or e~uivalent
support on which a casting mold or form unit 12 is supported,
being carried by its lower end. The form here is cylindrical and
its long axis is vertical. As i5 typical, the form includes an
inner core (not shown) surrounded by a steel jacket 14 having its
upper end encircled and reinforced by a steel band 16. The an-
nular space between the core and the jacket receives flowable con-
crete to form a section of pipe 18. ~ top or upper header ring
20 is placed on top of the upper end of the as-yet unset concrete
and this ring is shaped so as to give the upper end of the pipe a
somewhat annular tapered form of reduced diameter as respects the
basic diameter of the pipe. As is known in the art, this end is
the male end and fits into the female end of a neighboring pipe
section when the pipe is laid. The lower end of the pipe section
appearing here is formed as a bell or female end, the formation
following known design and processes.
The form is embraced from above by processing structure in-
cluding a pair of upright guide members 22 which are mounted on
the floor, rising at diametrically opposite sides of the form.
Each guide member slidably carries an upright slide 24 and these
slides are rigidly cross-connected by a transverse member spaced
above the form. A pressure head 26 of generally circular con-
figuration is interposed horizontally between the cross member
24 and the top of the form and is connected to a plurality o~
hydraulic or air cylinder and piston units 28, the connections
being effected as at 30 (Fig. 2). The cylinders of these units
are carried by the cross member 24 and retraction and extension
of the pistons causes raising and lowering of the pressure head.
The pressure head applies down pressure to the top header ring
20 and holds the ring in place during settling, etc., of the con-
crete, conventionally accomplished by vibrators or the like (not
shown~. Diametrically opposed portions of the pressure head are
controlled or guided by projections 32 cooperating with the slides
24 to maintain the attitude of the pressure head during its ver-
tical movement.
As best shown in Figs. 8 and 9, the top ring 20 carries aninternal groove-forming ring 34, having a radial split at 36 and
detachably secured within the top ring by a plurality of recessed
bi8
cap screws 38 via holes 39 in the ring 34 and tapped bores in the
ring 20. The purpose of this ring is to form an annular groove
in the top or male end of the pipe, as at 40 in Fig. 8. ~s will
be understood from this Figure, the ring 34 is released from the
header ring by removal of the cap screws, leaving the snap ring
in place in the pipe groove as the top ring is removed upwardly.
Because of the split at 36, the ring 34 can be easily removed
from the groove after the concrete has set, etc.
It is a feature of the invention that the top ring may be
rotated about the axis of the pipe section during the forming of
the section. For this purpose, there is journaled in and below
the pressure head, by a central bearing 42 of any suitable nature,
a circular rotor 44. This rotor has, rigid on its under side, a
plurality of radially elongated driving ribs 46 (Fig. 3). The
top ring 20 has a like plurality of upstanding lugs 48 rigid
thereon. In the present case, there are three lugs and three
ribs. The purpose of the elongated ribs is to enable the rotor
to accommodate rop rings of different diameters, it being clear
that smaller rings will have their lugs on a smaller circle than
larger top rings. This improves the versatility of the apparatus.
Clearly, when the rotor is turned, the ribs engage the lugs and
turn the top ring, thus troweling the male end of the pipe and
especially the groove 40 in that end. It is preferred that the
speed of rotation be relatively slow and the rotation unidirect-
ional for only a few revolutions, depending upon the diameter of
the pipe being cast.
Rotation of the rotor is accomplished in a novel manner as
follows: The periphery of the rotor has affixed thereto, as by
welding a circular band 50 to which is secured a link or roller
30 chain 52 (broken lines in Fig. 3; full lines in Figs. 5, 6, and
7), the length or circumference of the band 50 so that the chain
fits the band with little if any play. The chain is secured to
the band by a plurality of wings 54 welded to the chain links at
selected intervals, and these wings are in turn secured to the
band, as by any type of fastener, such as indicated at 56 (Fig.6). The pressure head has affixed thereto and is surrounded by
a depending annular shield 58 which encloses the chain from above
and about its circumference. The shield is interrupted at 60 to
provide for a supplementary enclosure 62 ~or a driving ~otor 64,
which may be air, electrically, etc., driven. As best seen in
Fig. 7, the motor carries and drives a relatively small driYer
in the form of a sprocket 66 that is in constant mesh with the
rotor chain 52. Obviously, the relative sizes of the sprockets
will determine the rpm of the motor, and these may be changed
according to the type or size of pipe being handled. It is pre-
ferred that the rpm be about two-and-one-hal~ revolutions per
minute and the amount of rotation be no more than one revolution.
Excess revolutions will erode the stripping medium normally used
between the concrete and the inner wall of the jacket.
Fig. 5 shows a further feature of the invention, residing in
a hardened-steel or the like internal wear/gap ring 68. Because
of the "activity" in this area of the jacket, resulting from ver-
tical and angular movement of the top ring, vibration of theconcrete, etc., small but abrasive particles of the mix find
their way past the periphery of the top ring and cause premature
wear on the interior of the jacket wall. By the interposition
of the wear/gap ring, premature wear of the entire jacket is
obviated, the wear ring being preferably welded in place.
The initial steps in the operation may follow those well
known in the art, at least up to the point at which the top ring
is positioned in place and down pressure applied by the pressure
head 26. Those skilled in the art are aware of the stage at which
pressure, vibration and rotation should occur. As already noted,
the down pressureon the pressure head and thus the top ring 20
is effected by the cylinder and piston units 24 and rotation of
the top ring is achieved via the motor 64, sprocket 66 and chain
52. At the appropriate time, rotation is halted, the pressure
head is raised and the form, together with the cast pipe section,
is moved to another area for further handling, such as removal of
the form, top and bottom rings and snap ring 34. It is common~
place to manufacture pipe via a process including several stations
at which the various steps are carried out. These details form no
immediate part of the present invention and hence are not illus-
trated and are described except only generally.
