Wire accessory

Abstract

The swaged accessory may be secured to the strand while providing a desired shape and size, thereby avoiding the need for subsequent material removal. In one application, the swaged fitting is secured to a strand by a forging operation such that the securely secured fitting provides a straight side configuration once secured to the strand. After the forging operation and without further material removal, the straight side of the finished fitting is substantially parallel to the longitudinal axis of the strand and the end face of the fitting is substantially perpendicular to the longitudinal axis. This arrangement provides a secure and effective force transfer interface for, for example, an end effector in a medical instrument.

Description

[0001] This application is a divisional application of an invention patent application entering the Chinese national phase with an application date of March 30, 2020, application number 202080066866.6, international application number PCT / US2020 / 025753, and name “Wire Accessories”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims the benefit of U.S. Provisional Application Serial No. 62 / 904,264, filed on September 23, 2019, and entitled Wire Attachments, the entire disclosure of which is hereby expressly incorporated herein by reference. Technical Field

[0004] The present disclosure relates to an accessory designed to be secured to a wire, and more particularly to a crimping accessory for use with a multi-strand or deformable wire or cord. Background Art

[0005] Wires are multi-strand wire structures used in a variety of actuation and force transfer applications. In the medical device industry, small diameter wires are used to actuate end effectors in medical devices, such as robotic surgical instruments. Such applications require a low profile or narrow centerline spacing, such as four or more wire elements anchored circumferentially around a small cylindrical axis.

[0006] In some applications, the cord includes a fitting swaged onto the cord along its length. The fitting can be used to actuate the end effector in one of two directions by applying a pulling force at one of the ends of the cord. The swaged fitting is used to transfer the pulling force from the cord to the end effector.

[0007] Known swage fittings may be swaged onto the wire at the desired location and subsequently subjected to a material removal operation, such as grinding or an EDM process, to form the shape and size required for actuation.

[0008] The above situation needs to be improved. Summary of the invention

[0009] The present disclosure provides a swaged fitting that can be secured to a wire while providing a desired shape and size, thereby avoiding the need for subsequent material removal. In one application, the swaged fitting is secured to the wire by a swaging operation such that the securely secured fitting provides a straight-sided configuration once secured to the wire. After the swaging operation and without further material removal, the straight sides of the finished fitting are generally parallel to the longitudinal axis of the wire, while the end faces of the fitting are generally perpendicular to the longitudinal axis. This arrangement provides a secure and effective force transfer interface for an end effector, such as in a medical device.

[0010] In one form thereof, the present disclosure provides an actuator assembly including a cord including a plurality of wire elements and having a pair of opposing terminal ends, and an accessory fixed along the length of the cord and spaced apart from each of the pair of opposing terminal ends. The accessory includes a body having a straight lateral sidewall defining a longitudinal body axis, a hole formed through the straight lateral sidewall of the body, and a pair of end faces defining opposing longitudinal ends of the body, the hole defining a longitudinal hole axis substantially perpendicular to the body axis.

[0011] In another form thereof, the present disclosure provides a precursor fitting for a cord, the precursor comprising a straight-sided body defining a longitudinal body axis and a hole formed through the straight-sided body. The hole defines a longitudinal hole axis that is substantially perpendicular to the body axis and is sized to receive the cord such that a void is formed between the cord and an inner surface of the hole. The precursor fitting further comprises a pair of end faces on opposite ends of the straight-sided body, and a pair of bosses on the respective pair of end faces. The pair of bosses collectively define a volume equivalent to the volume of the void.

[0012] In yet another form thereof, the present disclosure provides a method of securing an accessory to a cord, the method comprising passing the cord through a hole formed in the accessory, the cord having a plurality of wire elements and the hole defining a bore axis. The method further comprises impacting an end face of the accessory to deform material into the hole and into contact with the cord, and forming a substantially flat end face of the accessory substantially parallel to the bore axis by the impacting step. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The above and other features and advantages of the present invention and the manner in which they are achieved will become more apparent, and the present invention itself will be better understood, by referring to the following description of the embodiments of the present invention in conjunction with the accompanying drawings, in which:

[0014] Figure 1 is a perspective view of an accessory manufactured in accordance with the present disclosure shown as an accessory blank prior to being combined with a cord;

[0015] Figure 2 yes Figure 1 a front view of the accessory shown;

[0016] Figure 3 yes Figure 1 a side view of the accessory shown;

[0017] Figure 4 yes Figure 1 a perspective view, drawn to scale, of the plurality of accessories shown as coupled to the string and compared to a United States penny having a diameter of 0.75 inches;

[0018] Figure 5 yes Figure 4 another perspective view of one of the accessories and cords shown; and

[0019] Figure 6 is used by Figure 1-3 Production of accessory blanks shown Figure 4 and 5 A perspective view of the mold assembly of the accessory is shown.

[0020] Corresponding reference numerals indicate corresponding parts throughout the several views.The examples set out herein illustrate embodiments of the invention, and the embodiments disclosed below are not intended to be exhaustive or to be construed as limiting the scope of the invention in any way. DETAILED DESCRIPTION

[0021] The present disclosure provides a wire rope 120 ( Figure 4 and 5 ) accessory 100, and a method and equipment for producing the accessory.

[0022] Figure 1-3 The accessory blank 10 is shown, which is manufactured to be assembled to the cable 120 ( Figure 4 and 5 ) and fixed thereto, as further described below. The fitting 10 has a substantially cylindrical outer sidewall 12 that defines a longitudinal axis A1, and the fitting 10 also has a hole 14 formed through the sidewall 12 that defines a longitudinal axis A2. The axis A1 of the sidewall 12 is substantially perpendicular to the axis A2 of the hole 14, and the two end faces 18 of the fitting 10 are substantially perpendicular to the axis A1 and substantially parallel to the axis A2. This arrangement enhances the fitment 100 ( Figure 4-5 )Connect the cable 120( Figure 4-5 ) to an end effector (not shown), as further described below.

[0023] Although the accessory 10 is shown as having a cylindrical sidewall 12, other straight-sided sidewall designs may be used, such as a rectangular parallelepiped shape, etc. In general, such straight sides define a plurality of tangent planes, all of which are parallel to and thereby define the axis A1. In the case of a cylindrical sidewall 12, there are an infinite number of such tangent planes around the circumference of the sidewall 12. In the case of a rectangular parallelepiped sidewall, the four straight sides define four planes to define the axis A1 that is substantially perpendicular to the axis A2. The remaining two sides of the rectangular parallelepiped will then form the end faces 18. Other shapes may also be used in accordance with the present disclosure, including uniform prisms such as triangular prisms, hexagonal prisms, octagonal prisms, etc., or other rounded shapes, such as shapes that are elliptical in cross-section. For the purposes of the present disclosure, "substantially perpendicular" means defining an angle between 88 and 92 degrees.

[0024] In an alternative embodiment, the straight side wall 12 may form a draft angle relative to the axis A1. For example, Figure 1-4 The cylindrical side wall 12 shown may have a slight taper. Such a surface is still a straight side because the surface is straight in a front view (e.g., a view in the plane of the axis A1, such as Figure 3 A linear profile is defined in the view).

[0025] The fitting 10 includes a boss 16 centered on each axial end face 18. Each boss 16 is located above its adjacent axial end face and is calculated to define and contain a volume that will completely fill the void between the cable 120 and the inner surface of the hole 14 when a forging force is applied to the boss 16, as described below. In addition, each boss 16 is formed into a frustoconical shape, which is calculated to displace substantially all of the volume of the boss 16 into the above-mentioned void by deforming the forging material, thereby making each final outer surface 118 ( Figure 4 ) are substantially flat and aligned with their respective original end faces 18 ( Figure 1 ). For the purposes of this disclosure, "substantially flat" means that a surface has minor variations from its nominally defined plane, e.g., the maximum variation of the surface is less than 5% of its diameter (or other maximum lateral extent in the case of a non-circular surface). For example, Figure 4 , it can be seen that the original circular profile of boss 16 is still visible as a small indentation in fitting 100. However, such indentation extends less than 5% into the flat surface 118 defined by fitting 100, so that the entire surface can be referred to as "substantially flat".

[0026] exist Figure 1-3In the forging process described in detail herein, a pair of bosses 16 are shown and described on respective end faces 18. However, it is also contemplated to use a single boss 16 on one of the end faces 18. In such a configuration, the other end face 18 may be flat and may maintain substantially the same flat configuration before and after the forging process described in detail herein.

[0027] For non-cylindrical shapes used in conjunction with fittings made according to the present disclosure, the bosses can have complementary shapes having angled surfaces corresponding to each straight side surface of the finished fitting. For example, a rectangular fitting can include four angled surfaces, each of which intersects the outer surface of the fitting along a line parallel to a corresponding adjacent straight side surface. Other shapes can have angled surfaces that are similarly complementary to their straight side surfaces.

[0028] Figure 6 An exemplary apparatus 200 for a forging operation is shown that transforms an accessory blank 10 into a finished accessory 100 assembled to a cord 120. In the illustrated embodiment, the cord 120 is made of a plurality of separate integral wire elements that are wound or braided together. These separate elements can directly form the finished cord 120, or can form a number of multi-element strands that are then wound or braided together to form the cord 120. For medical device applications, for example, the cord 120 can have a total diameter between 0.0015 inches and 0.187 inches, and can be formed by separate elements as small as 0.0005 inches and 0.040 inches. In addition, the cord 120 can be made of special materials suitable for small medical device applications, including, for example, stainless steel, Co-Cr alloys, titanium alloys, shape memory alloys including NiTi (Nitinol), and tungsten.

[0029] In an alternative embodiment, the cord 120 may be made of polymer fibers or threads or yarns.Exemplary materials for polymer-based components include high-strength polymers such as Kevlar and Vectran.

[0030] The cord 120 is initially loosely connected to the accessory 10 by passing the cord 120 through the aperture 14. The aperture 14 is sized to easily receive the cord 120 so that a gap is formed between the inner surface of the aperture 14 and the various opposing outer surfaces of the cord 120. The cord 120 has a length defined between two end portions thereof, and the accessory 10 can be positioned along the length of the cord 120 and spaced apart from each end portion.

[0031] The accessory 10 is then placed on the die 202 of the forging apparatus 200 with the rope 120 assembled thereon. The die 204 is lowered to impact the upper boss 16 of the accessory 10 and to move along the axis A1 ( Figure 3) while the lower boss 16 is simultaneously subjected to equal forces from its contact with the die 204. These forces displace the volume of the boss 16 into the aforementioned void between the wire 120 and the hole 14. This material deformation eliminates the boss 16, causing the outer surface 18 to transform into a substantially flat outer surface 118 within the confines of the newly formed finished accessory 100. At the same time, the outer shape (e.g., cylindricity) of the outer surface 12 of the accessory 10 is maintained by being constrained within the die 204. After forging, the cylindrical outer surface 112 ( Figure 4 ) may be substantially the same as surface 12 or may be slightly enlarged. In any case, as the material of boss 16 is deformed into hole 14, the size and configuration of outer surface 112 is precisely controlled by die 204, thereby producing a straight-sided outer surface 112 having the same overall configuration as surface 12 described in detail above.

[0032] The deformation of material from bosses 16 into holes 14 combined with the external constraints provided by die 204 cause the material to deform into the various valleys and voids between the various wire elements and / or strands that make up multifilament cord 120. This creates a complex, multi-faceted interface between the deformed interior surfaces of hole 14 and the adjacent exterior surfaces of cable 120, which in turn creates a secure and reliable fixed connection between accessory 100 and cable 120.

[0033] As described above, boss 16 is shown as a frustoconical feature designed to deform during the forging operation as described above. However, boss 16 may take any shape or size as needed or desired for a particular application in order to fill any particular void during the forging operation.

[0034] In an alternative embodiment, a multi-sided die may be used to encapsulate the outer surface 12 of the fitting 10 during the forging operation, such as for applications where additional dimensional stability around the outer surface 12 of the finished crimp fitting 100 is desired.

[0035] Advantageously, the present method and apparatus facilitate the production of finished cable / accessory assemblies using a single pressing operation while maintaining high dimensional accuracy and excellent breaking load specifications. In an exemplary embodiment, for example, the accessory blank 10 can have a nominal outer diameter of 0.065 inches with a tolerance of ±0.001 inches. Its total length between surfaces 18 can be 0.045 inches with a tolerance of ±0.002 inches. The nominal diameter of hole 14 can be 0.026 inches with tolerances of +0.001 inches and -0.000 inches. Depending on the size and configuration of the mating cord 120, bosses 16 can be 0.007-0.009 inches higher than their respective adjacent surfaces 18. In the illustrated embodiment, bosses 16 define a platform with a diameter of 0.022 inches at their outer surfaces, and the base of bosses 16 has a diameter of 0.045 inches at their respective junctions with surfaces 18. Thus, the angled surface of boss 16 defines an angle of between 32 and 42 degrees with surface 18 , depending on the distance of boss 16 from surface 18 .

[0036] The accessory blank 10 and the accessory 100 can be made of any suitable material, such as stainless steel, Co-Cr alloy or titanium alloy, as may be required or desired for a specific application such as a medical device. The diameter of the accessory blank and the accessory 100 can be between 0.020 inches and 0.250 inches, for example, for medical device applications. In general, the accessory blank 10 and the accessory 100 can be softer and / or more ductile than the cord 120 in which the cord 120 is made of a metallic material. For example, the accessory blank 10 can be annealed and most or all of the cold working can be removed before the forging operation, while the cord 120 can include retained cold working after final processing (e.g., cold drawing). In an embodiment in which the cord 120 is made of a polymer, the accessory blank 10 and the accessory 100 may be harder than the cord 120.

[0037] exist Figure 6 After the forging operation shown and described above, the finished fitting 100 may have the specifications shown in Table 1:

[0038] Table 1. Finished product specifications for exemplary accessories

[0039]

[0040] Cords assembled to fittings made in accordance with the present disclosure can be efficiently mass produced while maintaining high dimensional tolerances as shown in Table 1. In addition, dimensional control is enhanced using the present method and apparatus because the outer surface of the fitting 10 does not require further processing after conversion to the fitting 100. Instead, the outer surface 12 can remain "as machined" after being secured to the cable 120. That is, the fitting 100 is ready for use after the forging operation without any further processing of the outer surface 112 or the end face 118. This also avoids any contamination or debris formed during the EDM or grinding processes associated with existing cord fittings, thereby making the present process compatible with clean room operations.

[0041] In addition, the cord 120 with the accessory 100 attached thereto exhibits the ability to withstand high and repeatedly applied forces. In a typical application, the cord 120 is used in a "pull-pull" actuation mode, where either end of the cord 120 is subjected to a pulling force designed to rotate the accessory 100. As the accessory 100 rotates, a rotational torque is applied to one of the end faces 118, and this torque can be used to drive a load, such as actuation of an end effector of a surgical robot. In this type of application, the accessory 100 shown in Table 1, when paired with a cord 120 having a baseline tensile strength well in excess of 100 lbf, exhibits the ability to withstand peak forces of at least 75 lbf and in some cases in excess of 100 lbf.

[0042] The accessory 100 also exhibits a high force tolerance for slippage relative to the cord 120. For example, in the exemplary embodiment shown and described herein, the accessory 100 can withstand a pull force of 80 pounds relative to the cord 120 without slipping from its original swaged-in-place position. More generally, accessories and cords made in accordance with the present disclosure can achieve a slip tolerance for the accessory for at least 80% of the breaking load of the cable to which the accessory is attached. This is superior to prior art devices that typically experience slippage at or below 60% of the breaking load, and is an important metric for medical device applications where slippage may result in unexpected actuation characteristics of the device.

[0043] The present apparatus and method of producing the accessory 100 also maximizes the wall thickness at the thinnest portion of the accessory 100 while remaining within any size and / or volume constraints specific to the end-use application. This maximized thickness contributes to the high force transfer and holding capabilities described above. The presence of the boss 16 retains a greater final minimum thickness than that of accessories applied by hammering or indenting a portion of the accessory for cable attachment, which can contribute to a strong finished assembly. For example, testing of the exemplary cord 120 and accessory 100 shown in Table 1 has demonstrated that the breaking load force of the finished assembly exceeds 60% of the breaking load of the cord 120 without any accessories attached.

[0044] Additionally, the overall finished volume of the accessory 100 may be reduced compared to prior accessory designs, thereby enabling a smaller cord / accessory assembly and, therefore, a smaller end effector device without compromising device capabilities and force transfer characteristics.

[0045] The fitting 100 can be attached to the cable 120 in a pre-passivated form, since no post-attachment processing such as grinding as described above need be performed. Thus, the process can remain compatible with certain cable materials (eg, tungsten) for which passivation would be a barrier to production.

[0046] In one application, the process can be automated or otherwise integrated into the manufacture of a finished device. For example, a device component can be used as a mold into which the accessory 110 is placed, so that the forging operation couples the accessory 110 to the cord 120 while also coupling the accessory 110 to its mating device component.

[0047] While the present invention has been described as having exemplary designs, the present invention may be further modified within the spirit and scope of the present disclosure. Further, this application is intended to cover departures from the present disclosure that come within known or customary practice in the art to which the present invention pertains.

Claims

1. An actuator assembly comprising: a cord comprising a plurality of wire elements, the cord having a pair of opposed terminal ends; and a fitting affixed along the length of the cord and spaced apart from each of the pair of opposed terminal ends, the fitting comprising: a body having straight lateral sidewalls defining a longitudinal body axis; a bore formed through the straight lateral sidewall of the body, the bore defining a longitudinal bore axis substantially perpendicular to the body axis; and A pair of end surfaces define opposite longitudinal ends of the body, wherein each of the pair of end surfaces is substantially flat across the respective end surface.

2. The actuator assembly according to claim 1, wherein: Each of the pair of end surfaces is substantially parallel to the bore axis.

3. The actuator assembly according to claim 1, wherein: The body of the accessory is one of a cylinder, a cuboid and a prism.

4. The actuator assembly according to claim 1, wherein: The straight lateral sidewalls of the body define a linear profile in the plane of the body axis.

5. The actuator assembly according to claim 1, wherein: The aperture includes a deformed inner surface that forms a multi-faceted interface having valleys and gaps between the plurality of wire elements of the cord.

6. The actuator assembly according to claim 1, wherein: The diameter of the wire is between 0.0015 inches and 0.187 inches.

7. The actuator assembly according to claim 6, wherein: The wire rope is made of one of stainless steel, Co—Cr alloy, titanium alloy, shape memory alloy including NiTi, and tungsten.

8. The actuator assembly of claim 6, wherein: The outer diameter of the fitting is between 0.020 inches and 0.250 inches.

9. The actuator assembly of claim 6, wherein: The fitting is capable of withstanding a tensile force of at least 80% of the breaking load strength of the line without slipping relative to the line.

10. The actuator assembly of claim 6, wherein: The fitting is capable of withstanding a rotational moment of at least 75 lbf relative to the line.

11. The actuator assembly of claim 1, wherein: The body defines a maximum lateral extent extending transversely from the longitudinal body axis, the substantially planar end surface extending over 95% of the maximum lateral extent.

12. The actuator assembly of claim 1, wherein: Each of the pair of end surfaces occupies a region defined by the straight-sided sidewalls.

13. A component blank system, comprising: A cord comprising a plurality of wire elements; as well as A straight-sided body defining a longitudinal body axis, the body comprising: an aperture formed through the straight-sided body, the aperture defining a longitudinal aperture axis substantially perpendicular to the body axis and sized to receive the cord such that a void is formed between the cord and an interior surface of the aperture; a pair of opposite ends of the straight side body; as well as A pair of bosses are located on the corresponding pair of ends, and the pair of bosses together define a volume equivalent to the volume of the gap.

14. The accessory blank system according to claim 13, wherein: Each of the pair of bosses defines an angled surface that intersects an adjacent one of the pair of end surfaces.

15. The accessory blank system according to claim 14, wherein: The angled surface forms a frusto-conical shape.

16. The accessory blank system according to claim 14, wherein: The angled surface is one of a plurality of angled surfaces corresponding to a side of the straight-sided body.

17. The accessory blank system according to claim 13, wherein: The pair of bosses are sized and configured to form a pair of opposing end surfaces after deformation of the material into the hole, the pair of opposing end surfaces being substantially planar and extending the entirety of each of the pair of ends.

18. A method of securing an accessory to a cord, comprising: passing the cord through a hole formed in the accessory, the cord having a plurality of wire elements and the hole defining a hole axis; impacting an end face of the fitting to deform material into the hole and into contact with the cord; and The end face of the fitting is formed by the impacting step and is substantially flat over the entire end face and substantially parallel to the bore axis.

19. The method according to claim 18, wherein: The impacting step includes impacting a boss located on an end surface of the fitting.

20. The method according to claim 19, wherein: The step of impacting the boss includes deforming material into the hole, the volume of the hole being substantially equal to the volume of the boss.

21. The method according to claim 20, wherein: The impacting step includes deforming material into interstices between the plurality of wire elements of the cord.

22. The method of claim 18, further comprising: The accessory is placed in a mold prior to the impacting step, whereby an outer surface of the accessory conforms to the mold after the impacting step.

23. The method according to claim 18, wherein: The accessories are positioned along the length of the cord, spaced apart from each respective end of the cord.

24. The method according to claim 18, wherein: The step of forming the end face of the fitting includes forming the end face of the fitting to occupy an area bounded by straight lateral sidewalls.

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