Needle curving apparatus

Abstract: An apparatus for curving a needle (30) is provided which comprises at least two generally cylindrical members (20,22) rotatably connected to a frame (12). At least one anvil shaft (24) is positioned substantially between the cylindrical members (20,22) and is rotatably connected to the frame (12). A needle (30) is positionable between the anvil shaft (24) and the cylindrical members (20,22) such that the needle (30) is curvable about the anvil shaft (24). A driving assembly (28) rotates at least one of the cylindrical members (20,22) and the anvil shaft (24) such that the needle (30) is curved about the anvil shaft (24) by advancement between the anvil shaft (24) and the rotatable members (20,22), and then expelled from the apparatus.

Description: The present invention relates to needle curving devices and is applicable to surgical needle curving devices for curving a plurality of needles simultaneously. The invention also relates to a method of curving needles. Surgical needle manufacture is an extremely precise and time consuming process, particularly where individual needles are formed one at a time. Conventional surgical needle manufacturing typically begins with the step of cutting round wire stock to a predetermined length. One end of the stock is then tapered to provide a cutting edge while the opposite end may be manipulated or processed to attain a flattened or other predetermined shape. Later, typically after almost all of the processing is completed, the stock is cut to its final length and then prepared for suture attachment. The needle may then be subjected to further processing, i.e., further refinement such as grinding, polishing and/or hardening. Curved needles have advantages over other needle configurations in many surgical procedures for a variety of reasons including, uniformity of entry depth for multiple sutures, and proper "bite" of tissue surrounding the incision or wound. When providing curved needles for surgical procedures it is desirable for the needles to have a specified curvature, i.e., a predetermined radius of curvature. The predetermined radius of curvature for the needle may vary with specific applications. Configuration of a needle includes curving or forming the needle into predetermined shapes and may be accomplished by using conventional curving methods. Such conventional curving methods may include bending a needle around an anvil structure having a desired curving surface to curve a needle to a predetermined radius of curvature. Where a curved needle is to have a bore for receiving a suture, it is desirable for the curving procedure to precede boring the needle so that the hole is not deformed by the curving procedure. To attain the desired needle configuration, the anvil structure provides a shaping surface for deforming the needle. Typically, a needle is positioned for curving by manually placing the needle for engagement with an anvil structure. The needle may be held by hand or placed in a holding device which is manipulated manually. It is further known that because needles are made of steel or similar springy materials, the anvil or mandrel used should have a smaller radius than the radius desired in the final needle to allow for some springback after the bending operation. A disclosure of such features may be found in, for example, U.S. Patent No. 4,534,771 to McGregor et al. One disadvantage to conventional needle curving is that only one needle can be curved around an anvil structure at a time. Moreover, the needle is positioned for engagement about an anvil surface using manual means. Further, during the needle curving process the needle may be damaged. It would therefore be desirable to provide a needle curving device that is capable of simultaneously curving a multiplicity of needles. It would further be desirable to provide a needle curving device to cooperate with a needle holding structure for positioning one or a multiplicity of needles for curving. It would further be desirable for a needle curving device to substantially avert damaging needles. It would also be desirable for a needle curving device to entertain substantially continuous needle curving. I would further be desirable to provide a needle curving device to curve a multiplicity of needles in predetermined configurations. FR-A-2385462 discloses apparatus for forming a wire, tube or strip into a helix to facilitate chemical treatment of a workpiece of great length within a treatment chamber which is shorter than would otherwise be necessary to accommodate the workpiece. According to one aspect of the invention, there is provided an apparatus for curving needles which comprises: a needle holding structure for positioning a multiplicity of needled for curving; a frame; at least first and second rotatable generally cylindrical members positioned in said frame; at least one rotatable anvil shalt positioned substantially between said cylindrical members and having a diameter substantially smaller than the diameter of the cylindrical members; means for holding at least one needle against said rotatable anvil shaft such that the needle passes between said anvil shalt and a first cylindrical member and between said anvil shalt and a second cylindrical member while being curved about said anvil shalt; and means for driving said cylindrical members and said anvil shalt. In a particularly useful embodiment of the invention, the holding member of the needle curving apparatus comprises a belt that is routed as a continuous web over the rotatable members and the anvil shalt for holding one or a multiplicity of needles between the rotatable members and the anvil shalt and for urging the needle or needles around the anvil shalt. The belt may be caused to move by the drive means and may frictionally engage and rotate the rotatable members and anvil shaft. The belt is preferably made of an elastomeric material to positively grip the needle and to substantially avert damage to the needle during the curving process. The needle curving apparatus provided may also be configured and adapted for working in concert with a needle holding structure for positioning a multiplicity of needles for curving. A plurality of rotatable members may also be provided which are positioned in spaced relation to the anvil shaft for holding and curving a needle around the anvil shaft. According to another aspect of the invention, there is provided a method of curving needles in which: a needle is advanced into a first nip between a first generally cylindrical member and a rotatable anvil shaft having a diameter substantially smaller than that of said first cylindrical member; the needle is pressed against the curved surface of the anvil shaft over a portion of its circumference to impart curvature to the needle; and the needle is extracted through a second nip between a second generally cylindrical member and said anvil shaft whose diameter is also substantially smaller than that of said second cylindrical member. The foregoing features of the present invention will become more readily apparent and will be understood by referring to the following detailed description of preferred embodiments of the invention, which are described hereinbelow with reference to the drawings wherein: Fig. 1 is a perspective view illustrating a curving apparatus according to one embodiment of the present invention; Fig. 2 is a cross-sectional view taken longitudinally through the belt of the apparatus of Fig. 1 illustrating the rotatable members and anvil shaft; and Figs. 3, 4, and 5 are enlarged cross-sectional views illustrating a curving sequence for a needle using the curving apparatus of Fig. 1. Referring to the drawings, in which like reference numerals identify identical or similar elements, Figs. 1-5 illustrate a preferred embodiment of a curving apparatus 10 in accordance with the present invention. The curving apparatus 10 includes a frame 12 having a rotatably mounted drive shaft 14 in the rear area of the frame 12. A motor assembly 16 rotates the drive shaft 14 at a predetermined speed. Drive shaft 14 respectively engages and rotates a belt 28 as described below. The motor assembly 16 may be of any conventional design having a power output capable of rotating the drive shaft 14 to perform the function described herein. Rotatable members shown as lower and upper cylinders 20 and 22, are rotatably mounted to frame 12. Conventional bearings (not shown) provide smooth and free rotation of the cylinders 20, 22. The cylindrical members may be solid, partially solid or hollow in cross-section. An anvil shaft 24 is rotatably mounted to the frame 12 in a position between the upper and lower rotatable cylinders 20, 22, as described below. The anvil shaft 24 is preferably made of a steel or other material having a hardness substantially equivalent to the hardness of the needles being curved. Thus, the anvil may have a Rockwell hardness value between about 55C and about 57C to discourage unwanted shaping or scratching of the needles and/or anvil. The anvil shaft 24 preferably has a solid cross-section. An idler shaft 26 is rotatably mounted to the frame 12 in a position generally above the horizontal plane of the drive shaft 140. The idler shaft 26 assists in providing stability for rotating belt 28. Belt 28 is routed in a continuous web over the drive shaft 14, the idler shaft 26, and the upper and lower cylinders 20, 22, as well as the anvil shaft 24. The belt 28 thus forms a closed loop about the rotatable members and is frictionally driven, for example, in a clockwise direction by the drive shaft 14. Belt 28 is preferably composed of material that is flexible enough to wrap about the rotatable members 20 and 22, and strong enough to assist in bending the needle 30 about the anvil 24 without damaging the needle. Such material include elastomeric materials having a durometer value between about 80 and about 90. Suitable materials for the belt include Neoprene. The belt 28 may be adjusted to enhance the frictional contact between the surface of belt 28 and the anvil shaft 24, drive shaft 14, idler shaft 26 and rotatable members 20 and 22. Idler shaft 26 may be loosened and its position on the frame 12 adjusted to allow adjustment of the tension on belt 28 or to facilitate the substitution of belts of different thicknesses. In the embodiment shown, belt 28 is preferably routed about the front portions of upper and lower rotatable cylinders 20, 22 and to the rear of the anvil shaft 24. In cross-section, the belt 28 generally has an "S" shaped configuration, as shown in Fig. 2. This positioning permits the anvil shaft 24 to provide a tensioning effect to the belt 28 and forms a needle curving portion 25 for curving needles. The belt 28 is further positioned about the rear of the idler shaft 26 and the drive shaft 14. The elastomeric nature of the belt 28 allows the belt 28 to translate the driving force from the drive shaft 14 to rotate cylinders 20, 22. Further, the belt 28 acts as a holding means for positioning needles 30 between the anvil shaft 24 and the upper and lower rotatable cylinders 20, 22. It is envisioned that the belt may have a layered structure, with the outermost layer being of an elastomeric material. Belt 28 may be made from any material capable of the functions described herein. The anvil shaft 24, rotatable member 20 and belt 28 are configured and dimensioned to form a space 27 at which a needle can be received for curving. For example, a needle 30 can be positioned at a needle curving portion 25 between the anvil shaft 24 and the belt 28. The upper cylinder 20 provides pressure from above on the belt 28. The belt 28 is sufficiently strong to avoid puncturing by the needle 30 during operation. The positioning of the belt 28 about the anvil shaft 24 also provides positive guidance of the needle 30 between the belt 28 and the anvil 24 as it is curved about the anvil shaft 24. The lower rotatable cylinder 22 provides pressure to the belt 28 from below. As the needle 30 is curved about the anvil shaft 24 and expelled from the apparatus it retains its curved shape. The needle's radius of curvature is determined by the diameter of the anvil 24 as it is curved about the anvil shaft 24 and by the material of construction of the needle. For example, a larger diameter anvil shaft 24 will produce a larger radius of curvature of the needle 30, and a smaller diameter anvil shaft 24 will produce a smaller radius of curvature of the needle 30. Typically, to provide a suitable radius of curvature for surgical needles, the anvil shaft 24 will have a diameter between about .200" and about .500". Preferably, the anvil shaft is removably mounted on frame 12 such that anvils of different sizes can be readily substituted to accommodate different size needles. The upper and lower cylinders 20, 22 are positioned in relation to the anvil 24 such that a needle 30 may be curved around the anvil 24 while maintaining sequential contact with the upper and lower cylinders 20, 22. It is also contemplated that the belt 28, as described above, will hold a needle 30 in place about the anvil 24 independently of the upper and lower cylinders 20, 22. In some configurations and/or materials of construction a needle may have a certain amount of spring back properties, i.e., the tendency for a structure to return to its original shape after being deformed. In cases such as these, the needle 30 can be curved beyond the desired radius of curvature by a predetermined amount so that it will spring back to a desired radius. Thus, where spring back properties require, it is contemplated by the present invention that a needle 30 may be curved about an anvil shaft 24 having a smaller diameter than the desired final radius of curvature of the needle. Further, it is also contemplated that an anvil 24 may be designed having differently configured cross-sections to appropriately shape a needle 30, for example, an anvil shaft having an elliptical cross-section. Referring to Figs. 3-5, in operation a needle 30 is positioned in the needle curving portion 25 adjacent to the upper cylinder 20 between the rotatable anvil 24 and the belt 28. The needle 30 is held in position by the frictional force between the anvil 24 and the belt 28 provided by the upper cylinder 20, and the tension of the closed loop of the belt 28. As belt 28 is driven in the direction of Arrow A, the needle 30 will be drawn in the direction of Arrow B. The needle 30 will initially follow the path of belt 28 and begin to curve around the anvil shaft 24. As shown in Fig. 4, the needle 30 is held between the belt 28 and the anvil 24 such that the needle 30 travels around the outer surface of anvil shaft 24 and is thereby curved. The needle 30 is held between the belt 28 and the anvil 24 and makes indirect contact with the upper and lower cylinders 20, 22. As the needle 30 is curved around the anvil shaft 24, the distal end of the needle 30 continues to be positioned between the upper cylinder 20 and the anvil 24 while the proximal end of the needle 30 is between the lower cylinder 22 and the anvil 24. Referring to Fig. 5, the needle 30 continues to travel around the anvil shaft 24 until the distal end is between the lower cylinder 22 and the anvil shaft 24. Thereafter, the needle 30 is expelled from the curving apparatus 10 with a predetermined radius of curvature. Although the belt 28, driven by drive shaft 14 is coupled to a motor assembly 16, other motor assemblies or driving assemblies are contemplated such as, for example, a chain, or an endless web. In accordance with the present invention a multiplicity of needles may be simultaneously curved, particularly when used in cooperation with a needle holding structure. The invention also allows for continuous needle curving without damage to the needle. The claims which follow include embodiments additional to those illustrated and described in detail above.

Claims: An apparatus for curving needles which comprises: a needle holding structure for positioning a multiplicity of needles for curving; a frame (12); at least first and second rotatable generally cylindrical members (20, 22) positioned in said frame; at least one rotatable anvil shalt (24) positioned substantially between said cylindrical members and having a diameter substantially smaller than the diameters of the cylindrical members (20, 22); means (28) for holding at least one needle against said rotatable anvil shalt (24) such that the needle passes between said anvil shalt and a first cylindrical member (20) and between said anvil shalt and a second cylindrical member (22) while being curved about said anvil shalt; and means (16) for driving said cylindrical members and said anvil shalt. An apparatus according to Claim 1, wherein said anvil shalt is sufficiently elongate, that a multiplicity of needles can simultaneously be curved around said shaft. Apparatus as claimed in Claim 1 or 2 wherein the holding means comprises a belt (28) which wraps around part of the circumference of the anvil shalt (24). Apparatus as claimed in Claim 3 including means to drive the belt to advance forwardly around the anvil shaft. Apparatus according to Claim 3 or 4 wherein a single belt serves as both a driving belt and a holding belt. Apparatus according to any one of the preceding claims, wherein said anvil shaft has a diameter between 5 and 13mm (about .2" and about .5"). Apparatus according to any one of the preceding claims, wherein an elastomeric portion is provided on at least one of said rotatable members, said rotatable anvil shaft and said holding means. Apparatus according to claim 7, wherein said elastomeric material has a durometer value in a range of from 80 to 90. A method of curving needles in which: a needle is advanced into a first nip between a first generally cylindrical member (20) and a rotatable anvil shaft (24) having a diameter substantially smaller than that of said first cylindrical member; the needle is pressed against the curved surface of the anvil shaft over a portion of its circumference to impart curvature to the needle; and the needle is extracted through a second nip between a second generally cylindrical member (22) and said anvil shaft (24) whose diameter is also substantially smaller than that of said second cylindrical member (22). A method according to Claim 9 in which the pressing step is performed by a belt (28).

Inventors: BOGART MICHAEL W, BOGART, MICHAEL W.
Applicants: UNITED STATES SURGICAL CORP, UNITED STATES SURGICAL CORPORATION
Application year: 1993
Main classification: B21G1
IPC codes: B21G1, B21F1