Filament wound pipe coupling

The pipe coupling includes a hollow cylindrical body and pipe registering means projecting radially inward therefrom centrally thereof. The body has a pair of inner annular grooves respectively adjacent opposite ends for the reception of sealing rings. Both the body and the pipe registering means are formed of glass fiber reinforced thermosetting resin and each contains glass filament windings. A plastic film strip between the body and the pipe registering means maintains them separate as the resin of both is cured. Thereafter, any cracking of the pipe registering means will leave the body intact and a good pipe joint will be maintained.

This invention relates generally to pipe couplings, and more particularly 
to a filament wound glass fiber reinforced thermosetting resin pipe 
coupling for pipes of relatively large diameter.

With respect to the drawings, a cart 10 for making pipe couplings 
constructed in accordance with the invention is shown in FIGS. 1 to 3. The 
cart 10 includes a frame 11 supported by four caster wheels 12. As shown 
in FIG. 3, a housing 14 is mounted at an end of the frame 11 adjacent a 
drive mechanism 16. Within the housing 14 two spaced aligned bearings 18 
are mounted on upper portions of suitable framework. A drive shaft 20 is 
rotatably mounted in the bearings 18 and extends through the housing 14. 
An end portion of the shaft 20 adjacent the drive mechanism 16 is 
connectable to a drive shaft 22 of the mechanism 16, and the other end 
portion of the shaft 20 has a generally cylindrical mold half 24 mounted 
thereon. 
Adjacent the other end of the frame 11 a carriage 26 is reciprocably 
mounted on a pair of guide rods 28 each mounted respectively adjacent 
opposite ends in a pair of mounting blocks 30 secured to the frame 11. 
Each rod 28 has a pair of spaced bushing blocks 32 reciprocably mounted 
thereon and secured to lower portions of suitable framework of the 
carriage 26 within a housing 34 thereof. Two spaced aligned bearings 36 
are mounted on upper portions of the framework of the carriage 26. A 
driven shaft 38 is rotatably mounted in the bearings 36 and extends 
through the housing 34. A locking bracket 40 is secured to the end of the 
housing 34 farthest from the housing 14. A locking pin 42 is insertable 
through one end portion of the shaft 38 and through a flange of the 
bracket 40 when it is desired to prevent the shaft 38 from rotating at 
times when the drive shaft 20 is not connected to the drive shaft 22 of 
the driving mechanism 16. A generally cylindrical mold half 44 is mounted 
on the other end portion of the shaft 38. Each of the mold halves 24 and 
44 has a push ring 46 removably secured thereto on its outer periphery at 
an end portion thereof remote from the other mold half. Further, each mold 
half has a segmented groove mold ring 48 removably secured thereto on its 
outer periphery generally centrally thereof. 
The drive mechanism 16 includes a housing 50 and suitable framework therein 
for mounting a motor 52, gear reducing mechanism 54 having an output shaft 
56, and a pair of spaced aligned bearings 58 for the drive shaft 22. The 
shafts 22 and 56 are operatively connected by an endless belt or chain 60 
and suitable pulleys or sprockets. 
When the drive shaft 20 of the cart 10 is connected to the drive shaft 22 
of the drive mechanism 16 and the mold halves 24 and 44 are secured 
together, energization of the motor 52 rotates the mold halves for a 
filament winding process as schematically illustrated in FIG. 1 where a 
plurality of strands 62 of continuous glass filaments are fed over a 
pulley 64, gathered into a single strand 66, fed into a bucket 68 
containing liquid resin, under a roller (not shown) in the bucket, out of 
the bucket and between a pair of rolls 70 for squeezing off excess resin, 
through a guide eye 72 mounted on an arm 74, and around the rotating mold 
halves 22 and 24. The arm 74 is movable in a controlled pattern axially of 
the shafts 20 and 38, by control mechanism not shown, to build up a 
filament wound glass fiber reinforced thermosetting resin pipe coupling on 
the mold halves 22 and 24. 
FIG. 4 shows the mold half 24 and FIG. 7 shows the mold halves 24 and 44 
joined together. A cast mounting plate 76 having four gussets 76a spaced 
ninety degrees from each other is mounted on a reduced end portion of the 
shaft 20 and rigidly secured to the full diameter portion thereof by the 
welding of the gussets 76a thereto. A similar mounting plate 78 having 
gussets 78a is similarly mounted on the end portion of the shaft 38. The 
generally cylindrical mold halves 24 and 44 are closed at one end. A flat 
mounting portion 24a of the mold half 24 is clamped between the mounting 
plate 76 and a clamping plate 80 having an apertured central boss 80a 
mounted on the reduced end portion of the shaft 20 and having four drilled 
and tapped bosses 80b spaced ninety degrees apart from each other and 
recessed in the portion 24a. Four bolts 82 are threaded respectively into 
the bosses 80b to clamp the portion 24a between the plates 76 and 80. 
Similarly, a flat mounting portion 44a of the mold half 44 is clamped 
between the mounting plate 78 and a clamping plate 84 having an apertured 
central boss 84a mounted on the reduced end portion of the shaft 38 and 
having four drilled and tapped bosses 84b spaced ninety degrees apart from 
each other and recessed in the portion 44a. Four bolts 86 are threaded 
respectively into the bosses 84b to clamp the portion 44a between the 
plates 78 and 84. 
The plate 78 is provided on an outer side with a pair of drilled and tapped 
bosses 78b spaced one hundred eighty degrees apart. Two studs 88 each 
provided with a hand knob 88a are threaded respectively into the bosses 
78b to secure the mold halves 24 and 44 together. 
The cylindrical portion of each of the mold halves 24 and 44 is provided on 
the inside with three anchoring lugs 90 spaced one hundred twenty degrees 
apart, for the purpose of removing a formed pipe coupling from the mold 
halves as later explained. 
The push ring 46 of each mold half is removably secured on the outer 
periphery thereof and adjacent the open end thereof by four bolts 92 
spaced ninety degrees apart and provided respectively with nuts 94. 
One of the segmented groove mold rings 48 is shown in FIG. 5 and includes a 
short segment 48a and two larger segments 48b and 48c. The end faces of 
the segment 48a lie in parallel planes, enabling the segment 48a to be 
removed by being pulled radially inwardly. The segment 48a is provided on 
its inner periphery with two spaced tapped blind holes 48d and each of the 
segments 48b and 48c is provided with three such holes, one of which is 
best shown in FIG. 6. The ring segments are secured to the outer 
peripheries of the mold halves 24 and 44 by knurled-head screws 95 
threaded respectively into the holes 48d and provided with lock nuts 96. 
A pipe coupling 98 constructed in accordance with the invention is shown in 
FIG. 8 in use with two pipes 99 and 100. Sealing rings 101 and 102 of 
elastomeric material are provided in the grooves formed in the coupling 98 
by the groove mold rings 48. The coupling 98 includes a pipe registering 
means or center register portion 98a only partially bonded to the rest of 
the coupling due to the presence of a plastic film strip 104. A surface 
mat 106 and a non-woven mat 107 are provided adjacent the inner surface of 
the coupling 98 between the sealing rings 101 and 102. Further, a mat 108 
of woven glass fiber roving is provided in the coupling 98 intermediately 
of the wall thickness and extending substantially the full width of the 
coupling 98. The remainder of the coupling 98 is resin and glass filament 
windings. 
With the mold halves 24 and 44 secured together by the studs 88, the push 
rings 46 and groove mold rings 48 secured in position, the locking pin 42 
removed from the shaft 38, and the shaft 20 connected to the shaft 22, 
preferably by a universal joint, isothalic resin impregnated continuous 
glass filaments are wound into the groove at the junction of the mold 
halves to form the center register portion 98a of the pipe coupling 98. An 
operator then manually winds the plastic film strip 104, previously cut to 
length, over the filled groove. Next, he winds the surface mat 106 and the 
non-woven mat 107 on the mold halves, the mats having been previously cut 
to length and saturated with bisphenol resin. Continuous glass filaments, 
impregnated with isothalic resin from the bucket 68, are wound over the 
mat 107 and rings 48 and the portions of the mold halves between the rings 
48 and the push rings 46 in a controlled pattern to build up the coupling 
98 about half way. Then the woven roving mat 108, previously cut to length 
but without resin impregnation, is wound on the half-formed coupling. 
Finally, continuous glass filaments, impregnated with isothalic resin, are 
wound over the mat 108 in a controlled pattern to complete the forming of 
the coupling 98. The shafts 20 and 22 are then disconnected and the cart 
10 is moved from the filament winding station to a curing station at which 
an electric heater cures the resin of the coupling. The cart 10 is then 
moved to a product removal station wherein a cylinder of a pneumatic 
actuator (not shown) is pinned first to one of the anchor lugs 90 of the 
mold half 44. The studs 88 securing the mold halves together are removed, 
and the screws 95 and bolts 92 are removed from both mold halves. A piston 
of the pneumatic actuator is then forced against the push ring 46 on the 
mold half 44 to pull the mold half 44 from the coupling 98 as the carriage 
26 retracts along the guide rods 28. The cylinder of the pneumatic 
actuator is then pinned to one of the anchor lugs 90 of the mold half 24 
and the piston is forced against the push ring 46 on the mold half 24 to 
move the push ring and the coupling 98 along the mold 24 to loosen the 
coupling. The coupling 98 is then removed from the cart 10 and the screws 
95 are threaded back into the ring segments 48a, 48b, and 48c. By prying 
against the heads of the screws 95, the ring segments 48a are removed from 
the coupling, after which the segments 48b and segments 48c are more 
easily removed. The ring segments are then reassembled on the mold halves 
24 and 44 along with the push rings 46 and the mold halves are secured 
together again by the studs 88 with the knobs 88a. The cart 10 may then be 
moved back to the winding station and the shafts 20 and 22 connected for 
the production of another coupling 98. 
The film strip 104 prevents the center register portion 98a from fully 
bonding to the rest of the coupling. Then if cracking of the center 
register portion 98a happens to occur, the remainder of the coupling will 
be intact and a good joint will be provided. 
It would be within the scope of the invention to replace the segmented 
groove mold rings 48 with one-piece rings, of elastomeric material, which 
would not have to be held in place on the mold halves 24 and 44 by screws 
95. 
Various other modifications of the coupling, apparatus, and method shown 
and described may be made without departing from the spirit and scope of 
the invention.