Adjustable collet

An adjustable collet is shown which includes a collet body having an internal bore and integral collet arms. An adjustment ring is received within the bore of the collet body and has a depending portion which engages the collet arms. By adjusting the position of the ring within the collet body bore and varying the longitudinal position of the depending portion relative to the collet arms, the effective collet arm length can be varied.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to collets of the type having a collet body 
and a plurality of depending collet arms which flex inwardly and outwardly 
and to such collets having an adjustment feature for varying the effective 
collet arm length. 
2. Description of the Prior Art 
Collets are used in a variety of mechanical structures, including oil well 
tools and equipment. The collet has a metal ring shaped body and a 
plurality of integral collet arms depending therefrom. The collet arms 
flex radially inward and outward with respect to a longitudinal axis drawn 
through the center of the bore of the collet body. U.S. Pat. No. 4,513,822 
to Gilbert, issued Apr. 30, 1985, and entitled "Anchor Seal Assembly", 
shows a seal assembly of the type used to anchor tubing within the bore of 
a surrounding conduit. A threaded collet circumscribes a portion of the 
exterior of the tubing and is stabbed into a mating profile within the 
bore of the surrounding conduit for latching the tubing within the 
surrounding conduit. In this and similar applications, it is often an 
advantage to be able to easily adjust the effective collet arm length to 
thereby increase or decrease the loading of the collet. That is, a longer 
relative collet arm length is more flexible and can handle stresses more 
easily without bending of the collet arms. A short relative collet arm 
length provides greater loading strength. 
It is an object of the present invention to provide a collet with an 
adjustment feature for easily varying the effective collet arm length. 
SUMMARY OF THE INVENTION 
The adjustable collet of the invention includes a collet body having an 
internal bore and a plurality of integral collet arms. An adjustment ring 
is received within the internal bore of the collet body. The adjustment 
ring has a depending portion which is adapted to engage collet arms. 
Connecting means are provided for engaging the adjustment ring within the 
collet body bore and for varying the longitudinal position of the 
adjustment ring relative to the collet arms, whereby the position of the 
adjustment ring relative to the collet body changes the effective collet 
arm length. Preferably, the adjustment ring is externally threaded and is 
engaged on a mating internally threaded surface of the collet body. In 
this way, screw threaded adjustment of the adjustment ring relative to the 
collet body changes the effective collet arm length. 
Additional objects, features and advantages will be apparent in the written 
description which follows.

DETAILED DESCRIPTION OF THE INVENTION 
FIG. 1 shows an adjustable collet of the invention designated generally as 
11. The collet 11 includes a metal ring or body 13 which has an upper 
internally threaded bore 15 and a plurality of integral collet arms 17 
which depend downwardly from the body 13. Each of the collet arms 17 is 
spaced apart from the next adjacent arm by a longitudinal opening 19. In 
the embodiment shown, the collet 11 is preferably provided with six collet 
arms 17 evenly spaced apart in circumferential fashion by openings 19. The 
upper bore 15 of the collet 11 widens in internal diameter to form a lower 
threaded bore 21. In the example of FIG. 1, the collet arms 17 are also 
externally threaded to form a thread profile 23 for latching engagement 
with a circumscribing conduit, as will be explained. The collet body 13 
has at least one set screw 25 which is located within a bore 27 which 
passes radially through the collet body into the internal bore 21. 
An externally threaded adjustment ring 29 is engaged on the internally 
threaded surface 21 of the collet body 13. The adjustment ring 29 is 
generally cylindrically shape and widens in external diameter at the lower 
extent thereof to form a collar portion 31. Externally threaded surface 39 
matingly engages the internally threaded surface 21 up the collet body. In 
the position shown in FIG. 1, the upper extent of the adjustment ring 29 
abuts an internal shoulder 33 formed by the junction of the bores 15, 21. 
The collar portion 31 of the adjustment ring 29 circumscribes the interior 
surface 35 of each of the collet arms and thereby engages the collet arms 
17 at a point of contact. 
As shown in FIG. 2, screw threaded adjustment of the adjustment ring 29 
relative to the collet body 13 varies the point of contact between the 
ring depending portion 31 and the interior surface 35 of the collet arms 
to thereby vary the effective collet arm length. The longitudinal position 
of the adjustment ring 29 can be varied by causing the ring externally 
threaded surface to travel along the lower threaded internal bore 21 of 
the collet body. This can be accomplished by any convenient means. For 
instance, the internal surface of the adjustment ring 29 can be provided 
with a profile for engaging an adjustment tool, or the lips 41, 43 of the 
ring can be provided with notches or the like for engaging an adjustment 
wrench. By whatever means, the adjustment ring position can be varied by 
causing the threaded surface 39 to travel along the collet threaded 
surface 21 to vary the effective collet arm length. Thus, the retracted 
position of the adjustment ring shown in FIG. 1 provides the maximum 
effective collet arm length and therefore the greatest flexibility and 
ability to handle stress. In the fully retracted position shown in FIG. 1, 
the adjustment ring lip 43 is received entirely within the bore of the 
collet body and does not extend past the origin of the opening 19. An 
intermediate, extended position of the adjustment ring 29, as shown in 
FIG. 2, shortens the effective collet arm length and enables the collet to 
bear a heavier load. 
FIGS. 3a and FIG. 3b show a typical application of the adjustable collet 11 
of the invention. In FIG. 3a, the threaded bore 15 of the collet is 
engaged on a mating externally threaded surface 45 of tubing member 47. 
The collet arm external thread profile 23 has been stabbed in and latched 
into engagement with a mating profile 49 of a circumscribing conduit 51. A 
seal ring 53 of a suitable elastomer and upper and lower packings 55, 57 
are carried about the exterior of the tubing member 47 for sealing within 
the bore 59 of the circumscribing conduit 51. By providing a longer 
effective collet arm length, the collet arms 17 can be more easily 
ratcheted into engagement with the profile 49. By shortening the effectie 
collet arm length, a greater load can be carried by the latch assembly. As 
shown in FIG. 3a, the adjustment ring 29 has been located at an 
intermediate position to optimize the features of flexibility and load 
bearing strength. 
While the invention has been shown in only one of its forms, it is not thus 
limited but is susceptible to various changes and modifications without 
departing from the spirit thereof.