Swage coupling including disposable shape memory alloy actuator

United States Patent m

Kapgan et al.

US005662362A [li] Patent Number: [45] Date of Patent:

5,662,362 Sep. 2, 1997

4,455,041 6/1984 Martin .

4,469,357 9/1984 Martin.

4,489,964 12/1984 Kipp et al. .

4,509,517 4/1985 Zibelin.

4,544,988 10/1985 Hochstein .

4,561,683 12/1985 Lumsden et al. .

4,563,876 1/1986 Banks .

4,836,586 6/1989 Martin 285/381.3

4,872,713 10/1989 Kapgan 285/381.3

4,934,743 6/1990 Kapgan et al. .

4,951,978 8/1990 Martin.

5,058,936 10/1991 Kapgan et al. .

5,409,268 4/1995 Wagner 285/381.1

Primary Examiner—-Eric K. Nicholson

Attorney, Agent, or Firm—Burns, Doane, Swecker &

Mathis, L.L.P.

[57] ABSTRACT

A threadless self-swaging coupling for joining or capping pipe. The coupling includes a coupling member and an actuating member of a heat shrinkable polymer material or a shape memory alloy material which undergoes a change in shape when heated from a martensitic state to an austenitic state. The coupling includes an inner sleeve and an outer ring surrounding the inner sleeve. The outer ring is movable with respect to the inner sleeve such that the inner surface of the inner sleeve is deformed radially inwardly and swaged to a pipe fitted therein when the outer ring is moved with respect to the inner sleeve. The outer ring is engaged with the actuating member such that the outer ring can be rotated with respect to the inner sleeve when the actuating member is heated into the austenitic state. The actuating member can be left in place or removed from the coupling.

21 Claims, 2 Drawing Sheets

1

SWAGE COUPLING INCLUDING
DISPOSABLE SHAPE MEMORY ALLOY
ACTUATOR

FIELD OF THE INVENTION 5

The invention relates to a swage coupling for forming a connection with one or more members wherein a change in configuration of an actuator provides a motion to a coupling member to form a swage coupling.

10

BACKGROUND OF THE INVENTION

Couplings between pipes must frequently be made in environments where it is difficult to manipulate conventional tools, such as wrenches, used to engage the couplings. In such environments, a great advantage is provided by selfswaging couplings that can form swaged couplings without the use of conventional tools. By using shape memory alloys ("SMA") in couplings, pipes can be swaged together using heat to activate the couplings rather than conventional tools.

Shape memory alloys possess the useful characteristic of being capable of changing physical dimensions upon heating above a transition temperature, A^ between a soft martensite phase and a hard austenite phase of the alloys. An SMA object can be processed while in a high temperature auste- 25 nitic phase to take on a first shape. After cooling the SMA object below M^ in the martensite phase without change of physical dimensions to memorize the first shape, the SMA object can be mechanically deformed into a second shape. The SMA object will remain in this second shape until 3Q heated to a temperature above A^ at which time the SMA object will transform to austenite and revert to its memorized first shape. An SMA member can exert large forces on adjacent members during the heat activated transition from the second shape to the first shape. 35

Coupling members incorporating SMA elements are well known in the art. In many conventional SMA couplings, a cylindrical element of SMA material either contracts or expands at the transformation temperature, Ap to apply a radial swaging force. Examples of these conventional SMA 4Q couplings can be found in U.S. Pat. Nos. 5,508,936; 4,951, 978, 4,489.964; 4,469357; 4.455,041; 4,424,991; 4,379, 575; 4.314,718; 4310,183; 4283,079; 4,281,841; 4,226, 448; 4,198,081; 4,149,911; 4,135,743; 4,035,007; 3,913,444 and 3,872,573. 45

U.S. Pat. No. 5,508,936 ("Kapgan") discloses a tubular coupling having an SMA collar with two internal teeth, one of which is swaged onto a tube by heating the collar, while the other is mechanically deformed to cause it to bite into the tube by drawing a tapered sleeve axially over the tooth. 50 Screw threads provide the means for axial movement

In addition to ring-shaped SMA elements which decrease in diameter upon thermal activation to effect self-swage couplings, a length reduction in SMA rods upon thermal activation has also been used to effect a radial compression. 55 For example, U.S. Pat No. 4.489,964 ("Kipp") discloses a connector for joining pipe ends in which the linear contraction of SMA rods draws together wedges at the ends of the rods, and these wedges then radially compress a collar element Devices utilizing transformation of SMA material 60 to effect a linear force used to produce a rotational motion are disclosed in U.S. Pat. Nos. 4.563.876 ("Banks"); 4,544, 988 ("Hochstein") and 4,509,517 ("Zibelin"). U.S. Pat. No. 3,801,964 ("DorreE") discloses a ring element of SMA to lock the joint of an electrical connector. U.S. Pat No. 65 4,561,683 ("Lumsden") provides a pipe coupling of the screw-thread type.

2

Conventional SMA couplings suffer a number of limitations resulting from the presence of SMA material in the swaged couplings. For instance, a service and storage temperature limitation arises with conventional SMA couplings because cooling a swaged SMA coupling to a temperature below Mf causes the SMA material to revert to a soft martensite phase which can result in weakening of the swaged coupling. Mother disadvantage is the weight and cost limitations due to the relatively high weight and density of SMA material as compared to other materials used in mechanical couplings, and the requirement that conventional SMA couplings incorporate a large amount of expensive SMA material to generate a swaging force. A further disadvantage is that SMA materials can be difficult to machine into the shapes required by some conventional SMA coupling designs.

There is a need in the art for a coupling that overcomes the service and storage temperature restrictions, the relatively high weight the expense and the manufacturing difficulties associated with conventional SMA couplings, while preserving the major advantages of these couplings.

SUMMARY OF THE INVENTION

The invention provides a coupling device for forming a swaged joint with a member to be joined, the coupling device including a coupling member and an actuating member. The coupling member includes an inner sleeve and an outer ring surrounding the inner sleeve, the inner sleeve including an axially extending opening therein for receiving a member to be joined to the coupling member. The outer ring is movable such as by rotation with respect to the inner sleeve and an inner surface of the inner sleeve is deformed radially inwardly by moving the outer ring with respect to the inner sleeve. The actuating member is engaged with the outer ring so as to move the outer ring upon a temperature induced change in configuration of the actuating member. The actuating member comprises a piece of material such as a shape memory alloy or heat shrinkable polymer which undergoes the temperature induced change in configuration upon heating the actuating member from a first temperature at which the material is in a first configuration (e.g., the shape memory alloy is in a martensitic state) to a second temperature at which the material is in a second configuration (e.g., the shape memory alloy is in an austenitic state).

The coupling device can incorporate various features. For instance, the outer ring can comprise a first outer ring and the coupling device can further include a second outer ring surrounding the inner sleeve. The second outer ring is movable with respect to the inner sleeve when the actuating member undergoes the temperature induced change in configuration and an inner surface of the inner sleeve is deformed radially inwardly by moving the second outer ring with respect to the inner sleeve. The actuating member can extend helically around the inner sleeve between points of attachment on the first and second outer rings whereby the first and second outer rings are moved such as by rotation in opposite directions by heating the actuating member to the second temperature.

The inner sleeve can include at least one outwardly extending projection on an outer surface thereof and the outer ring can include at least one inwardly extending projection on an inner surface thereof, in which case the inwardly extending projection engages the outwardly extending projection and deforms the inner surface of the inner sleeve radially inwardly when the actuating member is heated to the second temperature. According to a preferred