JP2003526177A - Multifilament nickel-titanium alloy drawn superelastic wire - Google Patents

Abstract

Abstract: A highly flexible cable (100) includes two, preferably three or more strands, a nickel-titanium alloy wire (102, 104, 106). The wires pair to form a wire rope (108). The nickel-titanium alloy wire rope (108) is drawn through a continuous die (110) so that the outer surface of the cable (100) is substantially smooth, the cross section of the entire cable (100) is circular, and the wire is The overall diameter of the rope (108) is reduced by 20-50%. The cable (100) is then annealed to remove the effects of cold working. The resulting cable is found to have improved flexibility (i.e., lower modulus) as compared to single-strand nickel-titanium wires of the same diameter (102, 104, 106). ing.

Description

Detailed Description of the Invention

This application is related to US patent application 08/843, filed May 2, 1997.
405, partly continued application, US patent application 08 / 963,686, filed Nov. 4, 1997, partially continued application, PCT US 97 filed, Oct. 7, 1997 / 18057 is a partial continuation application, 1996
U.S. Patent No. 08 / 730,489 filed October 11, 2010 (currently abandoned)
And US patent application Ser. No. 08 / 856,571 (now abandoned) filed May 15, 1997, all of which are incorporated herein by reference in their entirety. It is included in the book.

[0002]

BACKGROUND OF THE INVENTION

[0003]

FIELD OF THE INVENTION

The present invention relates to wires having a low elastic modulus. More specifically, the present invention relates to improvements in nickel-titanium alloy wires. The present invention is applicable to many technologies, including some of the guide wire technology of that patent application, other electrical cable technologies of that patent application, and the like.

[0004]

[Current technology]

The wire is manufactured from the ingot using a rolling mill and a drawing bench. A preliminary heat treatment of the material to be manufactured into the wire is carried out in a rolling mill, in which the incandescent billet (square cross section ingot) is rolled into a round wire rod. The action of atmospheric oxygen forms a mill-scale coating on the hot surface of the rod which must be removed. This descaling uses various physical methods (
For example, shot blasting) or pickling, ie by immersing the wire rod in a bath of a mixture with dilute sulfuric acid or hydrochloric acid or hydrogen fluoride. After pickling, the wire rod is subjected to vibration heat treatment, and this heat treatment causes the scale loosened by the acid to fall off. The remaining acid is removed by immersing the wire rod in lime water.

The actual process of manufacturing the wire is called drawing and is performed on the metal in a cold state by a drawing bench. In the prior art FIG. 1, a simple drawing bench 10 is shown. The wire 12 has a number of holes of various sizes, such as
16 (die) is drawn through the drawing plate 14 provided. These dies have holes that taper from the diameter of the wire 12 entering the die to the smaller diameter of the wire 12 'exiting the die. The thick wire rod 12 is coiled on a vertical spool 18, called a swift, and a bevel gear 24.
Is drawn through the die by a rotating drum 20 mounted on a vertical shaft 22 driven by. The drum can be disengaged from the drive by a clutch 26. To thread the wire through the die, the end of the wire is sharpened to the tip and advanced through the die. The wire is held by the gripping device and quickly pulled through the die. This is facilitated by wire lubrication. Each time the die passes, the diameter of the wire shrinks by a certain degree. By successively passing the wire through successively smaller diameter dies, progressively thinner wires are produced. The dies used in the modern wire industry are usually precision manufactured tools made of tungsten carbide for thick dimensions or diamond for fine dimensions. The die design and construction is relatively complex, and the die may consist of single crystal natural or synthetic diamond, polycrystalline diamond, or tungsten and cobalt powders mixed together and cold pressed into the shape of nib carbide. It can be made of a wide variety of materials, including blends.

A sixteenth cross-sectional view is shown in prior art FIG. Overall, the die used for wire drawing includes an outer steel casing 30 and, as described above,
And an inner nib 32 which may be made of carbide or diamond. The die has a large diameter inlet 34, known as a bell, which
4 is shaped so that the wire entering the die draws lubricant with the wire. The shape of the bell increases the hydrostatic pressure and promotes lubricant flow into the die.
The area 36 of the die, where the diameter actually shrinks, is called the approach angle. This approach angle is one important parameter in die design.
The area 38 following the approach angle is referred to as the support area. This support area does not reduce the diameter, but creates a drag force on the wire. The primary function of this support area 38 is to allow the conical approach surface 36 to be refinished (to eliminate surface damage due to die wear) without changing the die exit. is there. The last area 40 of the die is referred to as the back relief. The back relief allows the metal wire to expand slightly as it leaves the die. This post relief also minimizes the potential for wear if the drawing process stops and the die becomes misaligned with the path of the wire.

Although wire drawing methods appear to be simple metal processing methods, one skilled in the art will appreciate that many different parameters affect the physical quality of drawn wires. Among these parameters, drawing stress and flow stress play one important role. If these parameters are not carefully considered, the drawn wire will have reduced tensile strength. For a description of the practical aspects of wire drawing, see Wire Journal, October 1979.
Journal) Light, Roger N. (Wright, Roger N.
), "Physical Analysis and Die Design (Mechanical Analysis)
is and Die Design), the complete disclosure content of which is incorporated herein by reference.

The wire manufacturing method described above can be used to manufacture different types of wires. Overall, various characteristics of the manufactured wire are of concern, depending on the technology in which the wire is used. These characteristics include, but are not limited to, electrical resistance, tensile strength and flexibility of the wire. While wire flexibility is important in other fields as well, wire flexibility is particularly important in the medical field, which utilizes wires for stents and guidewires. For this reason, medical technology has recently shown much interest in nickel-titanium (Nitinol), which exhibits superelastic characteristics.

[0009]

[Outline of the Invention]

Thus, one object of the present invention is to provide a nickel-titanium alloy cable with improved flexibility characteristics over prior art nickel-titanium alloy wires.

According to this purpose, which will be explained in detail below, the highly flexible cable of the invention comprises two strands of nickel-titanium alloy twisted to form a single wire rope, Preferably three or more are included. According to other embodiments, the wire rope is provided with a central core wire, while according to some embodiments the wire rope does not comprise a central core wire at all. The nickel-titanium alloy wire rope is drawn through a continuous die, the outer surface of the formed cable is substantially smooth, the cross section of the cable is substantially circular, and the overall diameter of the wire rope is 20-50. Reduce its diameter until it shrinks by%. The cable is then annealed to remove the effects of cold work and the cable / wire formed with or without the central core is a single strand nickel-titanium of the same diameter. It has been found to have improved flexibility (i.e., low modulus) as compared to wires.

Additional objects and advantages of the present invention will be apparent to those of ordinary skill in the art by reference to the detailed description of the accompanying drawings.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENT Twisted and pultruded cable without core wire . Referring to FIGS. 3-5, a highly flexible nickel-based nickel-
The titanium alloy cable 100 is manufactured by the following method. Three strands of nickel-titanium alloy (ie, Nitinol Nitinol) wires 102, 104, 106 are twisted together to form a nickel-titanium alloy wire rope 108 (without core wire). The wire rope 108 is drawn through the die 110 using known wire drawing methods and equipment, thereby reducing its diameter. The nickel-titanium alloy wire rope 108 is preferably continuously drawn through a diameter reducing die. During the drawing process, the wires 102, 10
4, 106 are plastically deformed. After the continuous drawing process is completed, the cable 1
00 has a generally circular cross section as shown in FIG. 5, but has increased flexibility for a single strand nickel-titanium alloy wire of the same cross sectional area, as described in more detail below. To do. If desired, the generally smooth surface of the cable 100 can be easily insulated with the extracted or co-extracted material.

According to a preferred embodiment of a stranded and drawn nickel-titanium cable without core wires, the wire rope 108 is continuously drawn through multiple dies of decreasing diameter. The resulting cable 100 is preferably about 25-50% smaller in diameter, preferably at least 30% smaller than the diameter of the wire rope 108. Example 1 A three-strand 0.254 mm diameter Nitinor wire is helically twisted with a lay length of about 2.032 mm to form a wire rope of about 0.533 mm diameter, 0.483 mm (0 0.019 inch), 0.457m
m (0.018 inch), 0.406 mm (0.016 inch), 0.356 m
It is fed through a continuous die of m (0.014 inch) and 0.330 mm (0.013 inch) diameter to form a Nitinor cable. It should be noted that after passing through each die, the Nitinol cable is rolled to a diameter slightly larger than the diameter of the die. Thus, after passing through the last die, the Nitinor cable has a diameter of 0.
． It was found to be 0.356 mm (0.014 inches) instead of 330 mm (0.013 inches). The Nitinol cable thus formed is then annealed at a temperature of about 500 ° C. for about 1 minute, and the effect of the cable on the cold process is affected.
Get rid of. The resulting twisted, drawn Nichinoru cable pieces were bend radius tested by wrapping the cable pieces around pins of different diameters and by sandwiching the cable with a pair of pliers, and Simulate a zero-diameter bend. Comparative test 0.356 mm (0.014 inch) Nitinol wire (single strand)
Was carried out. The results of the bending test are listed in Table 1 with the percent recovery calculated by the formula (180 ° -X °) / 180 °, where X ° is the wire or cable strain of the wire before bending. It is the angle from the longitudinal axis.

Table 1 Pin diameter (mm)% restored NiTi cable% restored NiTi wire 5.105 mm 100 100 (0.201 inch) 4.292 mm 100 98.3 (0.169 inch) 3.937 mm 100 98.0 ( 0.155 inch) 3.531 mm 100 94.4 (0.139 inch) 3.073 mm 99.1 93.8 (0.121 inch) 2.362 mm 98.8 92.7 (0.093 inch) 1. 981 mm 98.0 91.6 (0.078 inches) 0.991 mm 96.1 63.8 (0.039 inches) 0.864 mm 91.6 55.5 (0.034 inches) 0.686 mm 95.8 53 .6 (0.027 inch) 0 Diameter bend 38.8 6.6 From the results of the tests in Table 1, according to the invention. It can be seen that switch Knoll cable is significantly increased flexibility compared to the Nitinol wire of the same diameter. For example, a Nitinol cable can be twisted around a pin having a small diameter of about nine times the diameter of the cable without incurring residual set (ie, near 100% recovery), while , Nitinol wire exhibits residual pitting when twisted around a pin having a diameter of about 12 to 13 times that of the wire. In addition, Nitinol cables have 9 times when twisted around a pin that has a diameter of about twice the cable diameter.
Recover by 0% or more. Nitinol wire, on the other hand, bends about 90 degrees when similarly twisted. Therefore, it can be seen that the recoverable elastic strain of the Nitinol cable is significantly lower than the recoverable elastic strain of the Nitinol wire. Further, the Nitinol cable of the present invention exhibits high elastic properties before entering the stressed martensitic phase. Example 2 A three strand 0.152 mm (0.006 inch) diameter Nitinol wire is twisted with a twist length of about 2.032 mm (0.08 inch) to about 0.330 mm.
(0.013 inch) diameter rope and 0.279 mm (0.013 inch)
1 inch, 0.254 mm (0.010 inch), 0.229 mm (0.00
9 inches, 0.203 mm (0.008 inches) and 0.178 mm (0.0
Feed through a 07 inch diameter continuous die to form a Nitinol cable. After each die, the Nitinol cable was squeezed to a diameter slightly larger than the diameter of the die. Thus, after the last die, the Nitinol cable diameter is 0.
It was 0.203 mm (0.008 inch) rather than 178 mm (0.007 inch). The Nitinol cable molded in this way is about 1 ° C at about 500 ° C.
Annealed for minutes to remove cold forming effects from the cable. The piece of Nitinol cable so twisted and drawn out mimics a zero diameter bend by wrapping the cable piece around pins of different diameters and by fastening the back of the cable to itself with pliers. . Comparative test is 0.203
It was performed on mm (0.008 inch) diameter Nitinol wire (single strand). The results of the bend radius test are shown in Table 2 with the percent recovery calculated according to (180 ° -X °) / 180 °, where X ° is from the longitudinal axis of the wire before bending to the wire or cable. Is the angle of the residual strain received by.

Table 2 Pin Diameter (inch)% Recovery NiTi Cable% Recovery NiTi Wire 0.247 100 99.2 0.231 100 99.2 0.201 99.9 99.4 0.169 99.9 99.4 0.139 99.7 99.6 0.109 99.4 98.3 0.078 99.0 98.2 0.050 99.3 92.5 0.040 97.5 61.7 0.027 97. 255.60 Diameter Bend 93.3 47.2 From the test results in Table 2, it is clear that the Nichiroll cable of the present invention has significantly increased flexibility as compared to Nichiroll wire of the same diameter. . For example, Nitinol cables have been found to be 99% or more recoverable when twisted around a pin having a diameter of only about 6 times the diameter of the cable. Nichiroll wire, on the other hand, loses such properties at twice its diameter (12 times the diameter of a cable). Furthermore, Nitinol cables recover more than 93% when gripped by pliers to mimic a 0 diameter bend, while Nitinol wires undergo a residual strain of greater than 90 °. Example 3 Three strands of 0.005 inch diameter nickel-titanium alloy (50 percent-50 percent) wire have a lay length of about 0.042 inch.
length) to form a wire rope of about 0.011 inch diameter, from which 0.0100 inch, 0.0090 inch, 0.0080 inch, 0.0075 inch and 0.0070 inch diameter wire ropes are formed. It is threaded through a continuous die into a nickel-titanium cable. When passed through the last die, the nickel-titanium cable is approximately 0.0080 inches in diameter. The nickel-titanium cable thus formed is then annealed for about 1 minute at a temperature of about 500 ° C. to remove the effects of cold work from the cable. As a result, the cable has very favorable flexibility properties. Furthermore, since there is no core wire,
If desired, a 0.0080 inch diameter cable can be trimmed to reduce the diameter. For example, a portion of a 0.0080 inch diameter cable may be tapered such that the tip portion terminates at, for example, a 0.0040 inch diameter or a 0.0025 inch diameter or other dimensional diameter. Alternatively, a portion of the 0.0080 inch diameter cable may be trimmed without tapering to form a tip portion of the desired diameter. Example 4 Four strands of 0.006 inch diameter Nitinol wire are twisted with a twist length of about 0.082 inch to form a wire rope of about 0.015 inch diameter, and then 0.014 inch, 0.013 inch, 0.
Passed through 012 inch, 0.011 inch, 0.010 inch and 0.009 inch diameter continuous dies and made into Nitinol cables. When passed through the last die, the Nitinol cable has a diameter of approximately 0.010 inches. The Nitinol cable thus formed is then subjected to about 500 degrees C for about 90 seconds.
Annealed at the temperature to remove the effects of cold work from the cable. As a result, the cable has very favorable flexibility properties. Example 5 Three strands of 0.015 inch diameter nickel-titanium alloy (51 percent-49 percent) wire have a lay length of about 0.110 inches.
length) to form a wire rope of about 0.032 inch diameter,
Then 0.029 inch, 0.026 inch, 0.024 inch, 0.022
It is threaded through a continuous die of inch and 0.020 inch diameter into a nickel-titanium cable. When passing through the last die, the nickel-titanium cable is about 0
． It has a diameter of 021 inches. The nickel-titanium cable thus formed is then annealed for about 75 seconds at a temperature of about 500 ° C. to remove the effects of cold work from the cable. As a result, the cable has very favorable flexibility properties. Example 6 Two strands of 0.010 inch diameter Nitinol wire and 0.00
Two strands of 5 inch diameter Nitinol wire joined together (0.01
Place a 0.005 inch diameter strand between 0 inch diameter strands),
Twisted with a twist length of about 0.080 inch to form a wire rope of about 0.020 inch diameter and then 0.018 inch, 0.016 inch, 0.014 inch, 0.012 inch and 0. Passed through a 0.011 inch diameter continuous die and made into a Nitinol cable. When it passed the last die, the Nitinol cable
It has an angled cross-section with a diameter of about 0.012 inches. The Nitinol cable formed in this way then has a thickness of about 50 seconds for about 60 seconds.
Annealed at a temperature of 0 degrees C to remove the effects of cold work from the cable. As a result, the cable has very favorable flexibility properties. Example 7 Three strands of 0.028 inch diameter Nitinol wire are twisted with a twist length of about 0.240 inch to form a wire rope of about 0.057 inch diameter and then 0.053 inch, 0.049 inch, 0.0
Passed through 45-inch, 0.041-inch and 0.037-inch diameter continuous dies,
It is called Nitinol Cable. When passed through the last die, the Nitinol cable has a sharp cross-sectional profile with a diameter of approximately 0.039 inches. The Nitinol cable thus formed is then annealed at a temperature of about 500 ° C. for about 90 seconds to remove cold work effects from the cable. As a result, the cable has very favorable flexibility properties. Twisted and pultruded cable with core wire Referring to FIGS. 6-8, a highly flexible nickel-titanium alloy cable 200 with a central core wire according to the present invention is manufactured by the following method. Nickel-titanium alloy (eg, nitinol) wires 202, 204, 20
6, 208, 210 are closely tied together (twisted) around the core wire 212 to form a nickel-titanium alloy wire rope 214. The wire rope 214 is pulled through the die 216 using known pulling methods. During the drawing process, the wires 202, 204, 206, 208, 210, 2
12 is plastically deformed. After the continuous pulling process, the cable 200 is
It exhibits a generally circular cross section as shown in FIG. 8, but exhibits greater flexibility for single strand nickel-titanium alloy wires of the same cross section, as will be described in more detail below. If desired, the substantially smooth surface of the cable 200
It can be easily insulated by extrusion or coextrusion materials.

According to this preferred embodiment of a stranded and drawn nickel-titanium alloy cable with core wire, the wire rope 214 is drawn continuously through multiple dies of decreasing diameter. The resulting cable 200 has a diameter that is about 20% to 50%, preferably at least 30% smaller than the diameter of the wire rope 214. Example 8 As shown by FIGS. 7 and 8 above, a Nitinol wire consisting of five strands and having a diameter of 0.254 mm (0.010 inch) was prepared from a single strand and having a diameter of 0.254 mm ( A wire rope with a diameter of approximately 0.762 mm (0.030 inches) that is helically twisted around a 0.010 inch (Nitinol) core wire with a twist length of approximately 2.032 mm (0.080 inch). And has a diameter of 0.711 mm, 0.635 mm, 0.559 mm, 0.483 m.
m and 0.432 mm (0.028 inch, 0.025 inch, 0.022 inch, 0.019 inch and 0.017 inch) dies are fed through to form a Nitinol cable. After passing through each die, the Nitinol cable returns to a diameter slightly larger than the diameter of the die. Therefore, the diameter of the Nitinol cable after passing through the last die is 0.457 mm instead of 0.432 mm (0.017 inch).
mm (0.018 inch). The Nitinol cable thus formed is then annealed at a temperature of about 500 ° C. for about 1 minute to remove the cold working effect from the cable. The Nitinol cable of the present invention exhibits extremely high flexibility compared to Nitinol wire of the same diameter. The recoverable elastic deformation of a Nitinol cable is much greater than the recoverable elastic deformation of a Nitinol wire. Moreover, the Nitinol cable of the present invention exhibits high elasticity before entering the stress-induced martensitic phase. Example 9 Six strands of a 0.125 mm (0.006 inch) diameter nitinol wire are wound around a single strand of a 0.125 mm (0.006 inch) diameter nitinol core wire at about 0. The wire rope having a diameter of about 2.032 mm (0.018 inch) is helically twisted with a twist length of 457 mm (0.080 inch) to form a wire rope having a diameter of 0.432 mm, 0.381 mm, 0. 356 mm
, 0.330 mm and 0.305 mm (0.017 inch, 0.015 inch,
A series of 0.014 inch, 0.013 inch, and 0.012 inch) dies were driven into the Nitinol cable. After passing through each die, the Nitinol cable returned to a diameter slightly larger than the diameter of the die. Therefore, the diameter of the Nitinol cable after passing through the last die was 0.330 mm (0.013 inch) rather than 0.305 mm (0.012 inch). The Nitinol cable thus formed was then annealed at a temperature of about 500 ° C. for about 1 minute to remove the effects of cold working from the cable. The resulting cable exhibited very favorable flexibility. Example 10 Three strands of Nitinol wire with a diameter of 0.254 mm (0.010 inches) are wrapped around a single strand of Nitinol core wire with a diameter of 0.254 mm (0.010 inches) at about 0. A wire rope having a diameter of about 2.032 mm (0.028 inch) is spirally twisted with a twist length of 457 mm (0.080 inch) to form a diameter of 0.635 mm, 0.559 mm, 0. 483 mm
, 0.406 mm and 0.330 mm (0.025 inch, 0.022 inch,
0.019 inch, 0.016 inch and 0.013 inch) dies are fed through to form a Nitinol cable. After passing through each die, the Nitinol cable returns to a diameter slightly larger than the diameter of the die. Therefore, the diameter of the Nitinol cable after passing through the last die is 0.356 mm (0.014 inch) rather than 0.330 mm (0.013 inch). The Nitinol cable thus formed was then annealed at a temperature of about 500 ° C. for about 1 minute to remove the effects of cold work from the cable. The resulting cable exhibits very favorable flexibility. Example 11 A single strand of nickel-titanium alloy (50% -50%) having a diameter of 0.010 inches around a single strand of core wire of nickel-titanium alloy (50% -50%) having a diameter of 0.010 inches. Four strands of wire are twisted in a spiral shape so that the lay length is about 0.080 inch to form a wire rope with a diameter of about 0.030 inch. Feed to continuous dies with diameters 0.027 ", 0.024", 0.021 ", 0.018" and 0.015 "to form nickel-titanium cables. After passing through each die, the nickel-titanium cable rebounds to a diameter slightly larger than the diameter of that die. Therefore, after passing through the last die, the nickel-titanium cable has a diameter of 0.016 inches instead of 0.015 inches. The nickel-titanium cable thus formed is then about 500 ° C.
Anneal at about 1 minute to remove the effects of cold working from the cable. The cable obtained exhibits a very favorable flexibility. Example 12 A single strand of nickel-titanium alloy core wire having a diameter of 0.010 inches around a single strand of nickel-titanium alloy having a diameter of 0.010 inches (
51% -49%) 7 strands of wire with a twist length of about 0.0
The wire rope having a diameter of about 0.030 inch is twisted in a spiral shape so as to have a diameter of 80 inch, and the wire rope is wound with a diameter of 0.029 inch, 0.027 inch,
Feed to 0.024 inch, 0.021 inch and 0.019 inch continuous dies to form nickel-titanium cables. After passing through each die, the nickel-titanium cable rebounds to a diameter slightly larger than the diameter of that die. Thus, after passing through the last die, the nickel-titanium cable has a diameter of 0.020 inch instead of 0.019 inch. The nickel-titanium cable thus formed is then annealed at about 500 ° C. for about 1 minute to remove the cold work effect from the cable. The cable obtained exhibits a very favorable flexibility. Example 13 A single strand of Nitinol core wire having a diameter of 0.005 inches is wrapped around three strands of Nitinol wire having a diameter of 0.015 inches with a twist length of about 0.080 inches. To form a first wire rope having a diameter of about 0.025 inch, the wire rope being 0.023 inch, 0.020 inch, 0.017 inch,
Supply to 0.015 inch and 0.013 inch continuous dies with a diameter of about 0.0
Form a Nitinol cable that rebounds to 14 inches. The 0.014 inch diameter Nitinol cable thus formed was then about 7 ° C at about 500 ° C.
Anneal for 5 seconds to remove the cold working effect from the cable. The cable obtained exhibits a very favorable flexibility. Example 14 Eight strands of Nitinol wire having a diameter of 0.010 inches were wound around a single strand of Nitinol core wire having a diameter of 0.028 inches with a lay length of about 0. The first wire rope having a diameter of about 0.048 inch is helically twisted to form a wire rope having a diameter of 0.046 inch, 0.044 inch, 0.042 inch, and 0.04 inch. Feed 040 inch and 0.038 inch continuous dies to form a Nitinol cable that rebounds to a diameter of about 0.040 inch. The 0.040 inch diameter Nitinol cable formed in this way is then
Anneal at about 75 seconds to remove the effect of cold work from the cable. The cable obtained exhibits a very favorable flexibility. Example 15 Five strands of Nitinol wire having a diameter of 0.010 inches were wound around a single strand of Nitinol core wire having a diameter of 0.010 inches with a lay length of about 0. The first wire rope having a diameter of about 0.030 inch was twisted in a spiral shape to form a first wire rope having a diameter of about 0.030 inch, and the wire rope was fed to a continuous die, as shown in FIGS. A 0.018 inch diameter Nitinol cable 200 is formed as described in Example 8. The 0.018 inch diameter Nitinol cable is then preferably annealed. Referring to FIG. 9, a nitinol wire having a diameter of 0.010 inches is wrapped around a nitinol cable 200 having a diameter of 0.018 inches 8
Book strands 220,222,224,226,228,230,232,2
34 is helically twisted to form a new wire rope 236 having a diameter of about 0.039 inches with a twist length of about 0.080 inches. Referring to FIG. 10, the new wire rope 236 has a diameter of 0.037 inch, 0.035 inch, 0.
． Form a Nitinol cable 238 that is fed to 033 inch, 0.0315 inch and 0.030 inch continuous dies and rebounds to a diameter of about 0.032 inch. The Nitinol cable thus formed is then annealed at about 500 ° C. for about 75 seconds to remove the cold working effect from the cable. The cable obtained exhibits a very favorable flexibility. Example 16 Five strands of 0.25 mm (0.010 inch) diameter Nitinol wire are wound about 2.03 mm (0.008 inch) in diameter about one 2.03 mm (0.008 inch) nitinol core wire. 080 inches) is twisted in a spiral to form a first wire rope having a diameter of about 0.71 mm (0.028 inches), and 0.66, 0.61, 0. 53, 0.46, 0.38m
m (0.026, 0.024, 0.021, 0.018, 0.015 inch) diameter continuous die is passed through to obtain a 0.41 mm (0.016 inch) diameter (
Nitinol cable with (after recovery). 0.41 mm (0.01
A 6 inch Nitinol cable is preferably annealed. 0.18 mm (0.
Six strands of Nitinol wire with a diameter of 007 inches are 0.41 mm (0.
About 0.03 mm (0.08 mm) around a 016 inch diameter Nitinol cable
It is twisted in a spiral with a 0 "sideways length to form a new wire rope with a diameter of about 0.76 mm (0.032"). 0.76, 0.71, 0.66, 0
． 61, 0.56 mm (0.030, 0.028, 0.026, 0.024, 0
． Approximately 0.58 mm (0.0
Create a 23 inch diameter Nitinol cable that recovers. The so-formed Nitinol cable is annealed for about 75 seconds at a temperature of about 500 ° C. to remove cold work effects from the cable and the resulting cable exhibits highly desirable properties. Several examples of nickel-titanium alloy cables that exhibit highly favorable properties have been described and illustrated. While particular embodiments of the invention have been described, the invention should not be limited thereto in light of the claims and the specification. Thus, although a particular number of strands having a particular diameter has been disclosed, different numbers of strands (eg 5, 6, or more) and different diameters may be used. Further, although in some embodiments, the core wire was disclosed as a cable formed of a single nickel-titanium strand and multiple strands around the core wire, the core wire is described herein. The nickel-titanium cable formed by the method described above, and the core wire may have the same diameter or different diameters from the twisted wire. Also, although the strands have been shown to have helical twists and exceptional lateral lengths, other types of strand twists may be used and other lateral lengths may be utilized with similar success. . In fact, the lateral length is reduced, which makes the product cable more flexible. Moreover, although particular shapes have been disclosed with respect to the particular number of dies used and the particular reduction in rope diameter, other shapes may be used with a reduction of at least 20%, preferably 30%. Further, while annealing at constant temperature for a particular length of time has been described, other temperatures and times can be utilized to substantially maintain cold working of the cable. It will therefore be appreciated by those skilled in the art that other modifications can be made from the spirit of the invention and the description of the claims.

[Brief description of drawings]

[Figure 1]   It is a schematic perspective view of the wire drawing processing apparatus of a prior art.

[Fig. 2]   1 is a schematic cross-sectional view of a prior art drawing die.

FIG. 3 is a schematic view of a wire rope without a central core that is drawn through a die according to the present invention.

[Figure 4]   4 is a cross-sectional view taken along line 4-4 of FIG.

[Figure 5]   5 is a cross-sectional view taken along line 5-5 of FIG.

FIG. 6 is a schematic view of a wire rope having a central core that is drawn through a die according to the present invention.

[Figure 7]   7 is a cross-sectional view taken along line 7-7 of FIG.

[Figure 8]   FIG. 8 is a sectional view taken along line 8-8 of FIG. 6.

FIG. 9 is a sectional view of a wire rope according to another example before being drawn through a die according to the present invention.

[Figure 10]   FIG. 10 is a sectional view of a cable manufactured from the wire rope of FIG. 9.

─────────────────────────────────────────────────── ─── Continued front page    (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, I T, LU, MC, NL, PT, SE), OA (BF, BJ , CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, K E, LS, MW, SD, SL, SZ, UG, ZW), E A (AM, AZ, BY, KG, KZ, MD, RU, TJ , TM), AL, AM, AT, AU, AZ, BA, BB , BG, BR, BY, CA, CH, CN, CU, CZ, DE, DK, EE, ES, FI, GB, GE, GH, G M, HU, ID, IL, IN, IS, JP, KE, KG , KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MD, MG, MK, MN, MW, MX, N O, NZ, PL, PT, RO, RU, SD, SE, SG , SI, SK, SL, TJ, TM, TR, TT, UA, UG, US, UZ, VN, YU, ZW F-term (reference) 5G307 EA02 EA06 EF09                 5G325 BA08 BC02 BC03

Claims (29)

[Claims] 1. A nickel-titanium comprising at least two paired nickel-titanium wires that are drawn through at least one die to form a flexible cable having a substantially circular cross section. cable. 2. The nickel-titanium cable of claim 1, wherein the at least two paired nickel-titanium wires comprise at least three nickel-titanium wires. 3. The nickel-titanium cable of claim 2, wherein the cable has a cross-sectional diameter that is approximately 20% to 50% less than the diameter of the entire at least three paired nickel-titanium wires. -Titanium
cable. 4. The nickel-titanium cable of claim 2, wherein the at least three paired nickel-titanium wires are exactly three helically twisted nickel-titanium wires. cable. 5. The nickel-titanium cable of claim 1, wherein the at least one die comprises a plurality of dies with openings of progressively smaller diameter. 6. The nickel-titanium cable of claim 2, wherein the at least three paired nickel-titanium wires are 0.0127c.
A nickel-titanium cable having a diameter of m (0.005 inches) to 0.7112 cm (0.028 inches). 7. The nickel-titanium cable of claim 3, wherein the cable is 0.02032 cm (0.008 inch) to 0.9906.
A nickel-titanium cable having a substantially circular cross section with a cross sectional diameter of cm (0.39 inches). 8. The nickel-titanium cable of claim 1, wherein the at least two paired nickel-titanium wires have exactly four wires. 9. The nickel-titanium cable according to claim 8, wherein   A nickel-titanium cable, wherein each of the four wires has the same diameter. 10. The nickel-titanium cable according to claim 8, wherein among the four wires, the first two wires have a first diameter and the rest of the four wires. The second two wires of the nickel-titanium cable have a second diameter that is different from the first diameter. 11. The nickel-titanium cable of claim 1, wherein the at least two nickel-titanium wires are paired about a nickel-titanium core wire around the at least two nickel-titanium wires. And the core wire is drawn with at least one die to form a flexible cable having a substantially circular cross section. 12. The nickel-titanium cable of claim 11, wherein the core wire has a first diameter and at least one wire of the pair of wires has a first diameter. Nickel-titanium cables with different second diameters. 13. The nickel-titanium cable of claim 11, wherein the core wire is a flexible core cable having a substantially circular cross section, the flexible core cable being another nickel-titanium wire. A nickel-titanium cable comprising at least two additional nickel-titanium wires twisted around the core. 14. A method of making a nickel-titanium cable comprising: a) pairing at least two strands of nickel-titanium wire to form a single nickel-titanium wire rope; and b) said wire rope. Pulling through at least one die to form a cable having a substantially circular cross section. 15. The method of claim 14, wherein the at least two strands comprise at least three strands. 16. The method of claim 14, further comprising the step of: c) annealing the cable to remove cold work effects. 17. The method of claim 14, wherein the drawing step reduces the cross-sectional diameter of the entire wire rope by about 20-50%. 18. The method of claim 14, wherein the drawing step reduces the overall cross-sectional diameter of the wire rope by about 30-40%. 19. The method of claim 14, wherein the drawing step comprises performing continuous drawing through a plurality of dies of reduced diameter. 20. The method of claim 15, wherein the step of pairing the at least three strands comprises twisting exactly three strands in a spiral. 21. The method of claim 15, wherein the at least three strands comprise strands having a diameter of 0.0127 cm (0.005 inches) to 0.7112 cm (0.28 inches). Method. 22. The method of claim 14, wherein the cable is 0.02032 cm (0.008 inch) to 0.0006 inch.
A method having a cross section of cm (0.039 inch). 23. The method of claim 14, wherein the step of pairing the at least two strands comprises twisting exactly four strands in a spiral. 24. The method according to claim 23,   The method wherein each of the four strands has the same diameter. 25. The method of claim 23, wherein two of the four strands have a first diameter and the remaining two have a second diameter different from the first diameter. A method comprising: 26. The method of claim 14, wherein the step of twisting the strands of the at least two nickel-titanium wires is about the nickel-titanium core wire and at least two nickel-titanium wires around the core. A method comprising twisting the strands of. 27. The method of claim 26 further comprising: c) twisting at least two strands of nickel-titanium wire about the first cable around the second nickel-titanium wire. Forming a rope; and d) withdrawing the second wire rope through at least one die to form a second cable having a substantially circular cross-sectional shape. . 28. The method of claim 27, further comprising: e) forming the first cable and then annealing the first cable to remove the effects of cold working. how to. 29. The method of claim 28, further comprising: f) forming the second cable, then annealing the second cable to remove the effects of cold working. how to.