Hydraulic chuck having ring collet

A hydraulic chuck for engagement of the outside of tubes. A set of ring collets are provided to grip the tube and hold it while the tube is tested, expanded, or otherwise worked on. Seals are provided to prevent fluid flow between the tube and the chuck. A piston is actuated to engage and release the ring collets, and to engage the seal when the collets are engaged.

BACKGROUND OF THE INVENTION 
Fluid pressure operated devices for radially expanding portions of tubing 
are known, such devices being disclosed in U.S. Pat. Nos. 1,448,457; 
2,479,702; 2,938,562; and 3,200,627. Structures of these patents include 
fluid conveying mandrels receivable within the tubes, means for expanding 
the mandrels to hold the tubing, and die elements against which portions 
of the tubes are flared or otherwise formed by fluid pressure. These 
expanding devices are customarily used to provide shapped bulges in tubing 
for coupling purposes and the like. In addition, they are used to expand 
tubing to fit fins and other apparatus connected to the outer surface of 
the tubing. 
Several hydraulic chucks have been developed which are suitable for tightly 
gripping one end of the elongated tube while simultaneously delivering a 
tube expanding fluid. Among these U.S. Pat. Nos. 3,505,846; 3,813,751; 
3,962,769; and 4,189,162. 
One of the problems which continuously has plagued those users of hydraulic 
chucks is the inability of such chucks to accomodate relatively large 
diameter tubes such as those having diameters of from about 2 inches up to 
about 7 or 8 inches or more. While many of the designs are suitable for 
gripping the tube satisfactorily, it has not been possible to adequately 
seal the device. On the other hand, where the sealing may be effective, 
the device is inadequate for gripping the tube to hold it in position 
under the substantially high pressure delivered by the hydraulic fluid. In 
addition, many difficulties with present hydraulic chucks are incurred 
because the piston which is driven by the fluid to cause activation of the 
gripping means such as radial collets, forces the piston against the tube. 
In large diameter operations, the force required to cause the collets to 
adequately grip the tube often times causes damage to the tube or relative 
movement of the tube with respect to the collets. In any event, the damage 
to the tube renders the operation substantially more expensive if the 
tubes can be salvaged. Repair, or the use of substantially lower pressures 
prevent wide acceptance of hydraulic chucks for larger diameter tubes. 
Accordingly, a hydraulic chuck would be highly desireable that could be 
employed with large diameter tubes of at least 2 to 8 inches in diameter 
or larger. The device must be capable of gripping the tube firmly to 
prevent relative movement thereof during application of hydraulic 
pressure, while simultaneously be capable of gripping the tube without 
damaging the tube. 
SUMMARY OF THE INVENTION 
The present invention relates to a hydraulic chuck, comprising a plurality 
of parts in interworking relationship which accomplish the objects of the 
present invention. Specifically, the invention includes a hydraulic chuck 
device which has a piston means having a central axis and an annular 
extension along the axis and has an inner diameter sized to receive a 
tube. A seal cone means is positioned adjacent to this extension of the 
piston means to cooperatively define a seal cavity adjacent the tube. Seal 
means are located in the seal cavity to prevent passage of fluid between 
the piston and the tube. 
Ring collet means are attached to the cone means and are positioned to 
engage the tube upon compression of the ring collets. Ring collets are 
generally ring shaped devices having a flat portion which engages the 
outer surface of a tube such that the inner surface is forced against the 
tube upon axial compression of the ring collet. 
Body means are slideably mounted on the piston means to permit movement of 
the piston with respect to the body along the axis. The body means has 
means for restraining axial movement of the tube in one axial direction. 
Nose cone means are fixedly mounted on the body and are also attached to 
the collet means such that movement of the body with respect to the piston 
operates the ring collet means. Finally, power means for moving the piston 
with respect to the body to activate the seal means and the ring collet 
means are provided. 
In a preferred embodiment, the ring collet means includes a ring having a 
first surface parallel to the axis and positioned to engage the tube. A 
second surface is provided and is inclined from the first surface and is 
cooperatively sized to engage a similar surface on the seal cone means. 
Axial movement of the seal cone means toward the ring collet means 
transmits force through the ring collet to force the collet ring against 
the tube. Similarly, it is preferred that the ring collet means have a 
third surface inclined from the first surface and cooperatively sized to 
engage a similar surface in the nose cone means, whereby axial movement of 
the piston toward the ring collet means with respect to the body forces 
the ring collet against the tube. 
In another embodiment, the device includes a tube seat means fixedly 
mounted on the body and slideably mounted on the piston, said tube seat 
means being positioned to contact the end of the tube to prevent axial 
movement of the tube in one axial direction. This tube seat means, in a 
preferred embodiment, includes a plurality of dowel means mounted in the 
body and slideably passing through the piston to contact the tube, whereby 
the piston is moveable independent from movement of the tube. 
Preferred embodiments, seal means are provided between the body and the 
piston to permit relative movement of the piston with respect to the body 
without passage of fluid therebetween. The power means which causes 
movement of the piston with respect to the body may, in a preferred 
embodiment, include a pneumatic piston and cylinder between the piston 
means and the body means to cause the relative movement therebetween.

DETAILED DESCRIPTION OF THE INVENTION 
As shown in the FIGURE, the chuck 10 is generally described. The chuck 
includes a piston 12 having a central axis 13 and a central passage. 
Annular extension 16 extends along the axis 13 of the piston 12. Tube 17 
is positioned inside the diameter of the annular extension 16. Associated 
with the annular extension 16 of the piston 12 is a seal cone 18 which is 
connected to the extension 16 via retractor 20. The seal cone 18 and 
annular extension 16 define a seal cavity 22 in which an o-ring seal 23 is 
provided. Movement of the piston 12 in the direction of the seal cone 18 
causes compression of the o-ring 23 and an effective seal between the tube 
17 and the piston extension 16. 
The body 24 is mounted to the nose cone 25 via threads 26. Collet ring 27 
is mounted on the nose cone 25 and the seal cone 18. Movement of the seal 
cone 18 toward the nose cone 25 causes compression of the collet rings 27, 
whereby the collet ring 27 grips the tube 17. Since the flat surface 27a 
of collet ring 27 is sized to generally fit the tube 17, compression of 
the collet 27 causes the collet surface 27a to grip the tube 17 without 
damaging the tube itself. 
Second surface 27b is inclined with respect to surface 27a of the ring 
collet 27 and is cooperatively matched with the seal cone 18 such that 
movement of the seal cone 18 toward the ring collet 27 forces the collet 
ring 27 against the tube 17. Similarly, third surface 27c is inclined with 
respect to surface 27a of the ring 27 such that movement of the piston 12 
through extension 16 and ring cone 18 forces the collet ring 27 against 
the tube 17. 
O-ring 28 and back-up ring 29 are provided to prevent passage of fluid 
between the piston 12 and the body 24. Similarly, o-ring 30 and back-up 
ring 31 are provided for the same purpose. 
A plurality of dowels 32, are mounted in the body 24 and positioned to form 
a tube engaging seat 33. This tube seat 33 of the dowel 32 is positioned 
to contact the end of the tube 17 to prevent movement of the tube in one 
axial direction. The dowel 32 is also slideably mounted in the piston 12 
so that the piston 12 may move with respect to the dowel 32. This permits 
movement of the piston 12 and the annular extension 16 without movement of 
the tube 17. Preferrably, at least 3 dowels 32 are provided equally spaced 
about the circumferance of the cavity which the tube 17 enters. 
To provide a power means for activating the movement of the piston 12 with 
respect to the body 24 and the tube 17, an air cap 34 is fitted with 
connection to a pneumatic air supply, not shown, so that piston 35 can be 
driven by the air. O-rings 36 prevent escape of the fluid and forces the 
air piston 35 and the piston 12 to move with respect to the body 24. Bolts 
37 fixedly mount the air cap 34 to the body 24. Test connect 39 allows 
hydraulic fluid to enter the system through the body 24 and the piston 12. 
Additional holes can be placed in the piston 12 equidistant from the holes 
which dowels 32 pass through. 
In operation, the tube 17 is inserted into the device against dowel 32. 
Operation of the air piston 35 to the air cap 34 causes movement of the 
piston 12 with respect to the body 24. Movement of the piston 12 causes 
the annular extension 16 to engage the seal cone 18 and close the seal 
cavity 22 causing seal 23 to be urged against the tube 17. Collet ring 27 
is compressed by force of the seal cone against surface 27b and the nose 
cone against surface 27c so that flat surface 27a is urged against the 
tube 17. Seal and back-up ring combinations 28 and 29 and 30 and 31 
prevent passage of fluid between the piston 12 and the body 24. The tube 
is gripped firmly in the collet ring 27 so that fluid may be passed 
through the test connect 39 to the various operations by which hydrostatic 
testing and expanding can be performed. As it can be seen, the collet ring 
27 is suitable for gripping large diameter tubes in a manner heretofore 
not disclosed. 
When the testing or expanding operation is completed, pressure is removed 
from test connect 39 and air pressure is removed from the air cap 34. Air 
pressure is then applied to the "open" port 40, and forces air piston 35 
and bolt 42 to the right, pulling piston 12, annular extension 16, 
retractor 20 and seal cone 18 away from the ring collet 27. At the same 
time, pressure entering port 40 causes body 24 to move nose cone 27 away 
from ring collet 27. Annular extension of nose cone 25 (25a) and of seal 
cone 18 (18a) are spaced such that both conical sections of 27 (27b & 27c) 
are positively released from the mating surfaces of nose cone 25 and seal 
cone 18.