Abstract:
A process for manufacturing a surgical needle incorporates at least one pressing operation which, preferably, in conjunction with a trimming and/or etching process, ultimately forms the sharpened needle end. The grinding operation in the preferred process does not produce the primary sharpened edges of the needle, but, rather is incorporated, in one instance, to reduce excess needle material prior to the pressing operation. Consequently, the amount of flash material generated during pressing is substantially reduced. This feature desirably enhances the subsequent trimming and etching operations, and produces a needle which is extremely sharp, durable and exhibits an improved retention of sharpness over periods of prolonged use.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   The present application claims priority of U.S. Provisional Patent Application Ser. No. 60/546,129, filed on Feb. 20, 2004. The priority of this prior application is expressly claimed and the disclosure of which are hereby incorporated by reference in its entirety 

   BACKGROUND 
   Background of Related Art 
   Suturing needles for applying sutures, or stitches, by hand in cutaneous and subcutaneous tissue are well known in the art. The suturing needles are typically used to close wounds or adjoin adjacent tissue, often at the conclusion of a surgical procedure. Suturing needles are usually made from a cut blank of material such as stainless steel. The cut blank is metal-worked using well known machining techniques to form the suturing needle. The needle generally includes a shaft, a rear end portion with an aperture or channel to secure a suture thread and a needle head at a front end portion for puncturing skin and for passing through tissue. The needle head typically incorporates a sharpened needle tip at its distal end and cutting edges. Alternatively, the needle tip may be of a tapered configuration. Straight and curved needles including multiple curved configurations are also known the art. 
   Conventional methods for needle manufacture include subjecting a needle blank to a series of grinding operations to form the desired needle edges and needle point. However, the grinding operations are often operator dependent thereby increasing the potential for needle defects. In addition, sharpened needle edges formed via conventional operations fail to retain their sharpness over extended use. 
   SUMMARY 
   Accordingly, the present disclosure is directed to a process for manufacturing a surgical needle and a surgical needle thereby produced. The preferred process incorporates at least one pressing operation which, preferably, in conjunction with a trimming and/or etching process, ultimately forms the sharpened needle end. The grinding operation in the preferred process does not produce the primary sharpened edges of the needle, but, rather is incorporated, in one instance, to reduce excess needle material prior to the pressing operation. Consequently, the amount of flash material generated during pressing is substantially reduced. This feature desirably enhances the subsequent trimming and etching operations, and produces a needle which is extremely sharp, durable and exhibits an improved retention of sharpness over periods of prolonged use. 
   In one preferred embodiment, the process for manufacturing a surgical needle includes the steps of providing a surgical needle blank of biocompatible material, removing needle material (e.g., through a grinding process) from a peripheral portion of one end of the needle blank to define a needle end having a reduced cross-sectional dimension, pressing the needle end to form at least three intersecting surfaces on the needle end and forming cutting edges adjacent areas of intersection of the at least three surfaces to define a plurality of cutting edges on the needle end. The process may also include the step of coining the needle blank prior to grinding to define a needle end having first, second and third sides. Preferably, the second and third sides are subjected to a grinding process to remove material adjacent the respective sides. 
   In a preferred embodiment, the step of pressing includes form pressing the first, second and third sides to produce the at least three surfaces of the needle end. A die mechanism having a die arrangement with a die concavity therein may be provided. The die concavity defines a tapered characteristic whereby the cross-sectioned area occupied by the concavity decreases from one end of the concavity to the other end of the concavity. The needle end is positioned within the die concavity to impart a tapered configuration to the needle end. Preferably, the die cavity of the die mechanism defines a general triangular configuration having first and second pressing surfaces. The needle blank is positioned within the concavity of the die mechanism to impart a generally triangular-shaped cross-section to the needle end. The die mechanism may include a die punch positioned in opposition of the die concavity. The die punch engages the first surface of the needle end upon relative movement of the die punch and the die mechanism. The die punch may have a radiused surface to impart an arcurate surface on the first surface of the needle end. 
   Excess needle flash material may be created adjacent areas of intersection of the first and second surfaces, and the first and third surfaces of the needle end during the pressing step. This excess flash material is removed through a trimming operation. The trimming step or trimming operation preferably includes forming a crease line along the areas of intersection of the first and second sides, and the first and third sides of the needle end. The needle blank may then be subjected to an etching process to remove excess flash material and/or sharpen the cutting edges. Heat treating the needle blank is also preferable. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and, together with a general description of the disclosure given above, and the detailed description of the embodiment(s) given below, serve to explain the principles of the disclosure, wherein: 
       FIG. 1  is a block diagram of a preferred embodiment of a process of manufacturing a surgical needle in accordance with the principles of the present disclosure; 
       FIG. 2A  is a plan view of the coining dies utilized in the coining operation of the process of  FIG. 1 ; 
       FIG. 2B  is an axial view of the needle end subsequent to the coining operation; 
       FIG. 3A  is a top schematic view of the relief grind mechanism used in the relief grind operation of the process of  FIG. 1 ; 
       FIG. 3B  is a side schematic view illustrating the arrangement of the collet and collet holder relative to the grind wheel of the relief grind mechanism; 
       FIG. 3C  is an axial schematic view illustrating the arrangement of the needle blank relative to the grind wheel of the relief grind mechanism; 
     FIG:  3 D is an axial end view of the needle blank subsequent to the relief grind operation; 
       FIG. 4A  is a plan view of the bayonet die configuration used in the press operation of the process of  FIG. 1 ; 
       FIG. 4B  is a cross sectional view of the needle end engaged by the upper press during the press operation; 
       FIG. 5A  is a perspective view of the lower dies used in the trim operation of the process of  FIG. 1 ; 
       FIG. 5B  is an end axial view of the needle end subsequent to the trim operation; 
       FIG. 6  is a side plan view of the needle end subsequent to the quick grind operation of the process of  FIG. 1 ; 
       FIG. 7A  is a side view of a pair of dies utilized in the flat press operation of the process of  FIG. 1 ; 
       FIG. 7B  is a top plan view of the needle end subsequent to the flat press operation; and 
       FIG. 7C  is a cross-sectional view taken along lines  7 C- 7 C of  FIG. 7B  illustrating the configuration of the main body of the needle. 
   

   DESCRIPTION OF PREFERRED EMBODIMENTS 
   Preferred embodiments(s) of the process for manufacturing a surgical needle of the present disclosure will now be described in detail with reference to the drawings wherein like reference numerals identify similar or like elements throughout the several views. 
   Referring now to the block diagram of  FIG. 1 , there is illustrated a preferred process for needle manufacture in accordance with the principles of the present disclosure. A needle blank in the form of a cylindrical rod having a desired or predetermined length is provided. The needle blank is to be eventually formed into a surgical needle. The needle blank may be cut from suitable biocompatible needle stock, including stainless steel, titanium or titanium alloys. The needle blank also preferably has a drilled recess (e.g., through laser drilling) in one end for receiving a surgical suture to attach the suture to the needle. It is also contemplated that the needle blank may have an open channel, an eye, etc. for receiving and attaching the suture as is known in the art. 
   With reference to  FIGS. 1 and 2A , the first step in the preferred process is a coining operation  100 . The coining operation imparts a desired cross-sectional configuration to needle blank  10 . The needle blank  10  is preferably placed within a collet (not shown in  FIG. 2A ). Any conventional collet adapted to secure a needle blank in fixed relation may be utilized. The collet may be indexed to determine and/or control orientation of the needle blank  10  relative to a collet holder employed in the remaining operative steps. The collet and needle blank  10  are mounted in relation to a die mechanism  102  of the coining operation. In one embodiment, the collet may be mounted within a collet holder (not shown) of the die mechanism. 
   The preferred die mechanism  102  includes two lower dies  104  and a planar upper die  106 . Lower dies  104  incorporate inclined swaging or coining surfaces  108  which extend at respective angles θ,−θ relative to transverse axis “r” of the dies  104 . Coining surfaces  108  define a concavity or recess  110  within lower dies  104 . Angles θ,−θ may be any oblique angle. Preferably, angles θ,−θ have an absolute value ranging from about 40° to about 70° relative to axis “r”. In one preferred embodiment, the absolute value of angles θ,−θ is about 58°. Other angular orientations are also envisioned. Dies  104 ,  106  are preferably formed of a carbide material although other materials are envisioned as well. 
   Needle blank  10  is positioned within concavity  110 . The die mechanism is actuated to advance upper die  106  toward lower dies  104  to swage or coin at least the needle end  12 . This coining operation  100  imparts a generally triangular shaped cross-section to the needle end  10 .  FIG. 2B  illustrates in axial view the configuration of the needle end  12  of the needle blank  10  subsequent to the coining operation. As appreciated, the end surface  14  of needle end  12  is substantially planar or flat. The three sides of needle end  12 , namely sides  1 ,  2  and  3 , generally define an equilateral triangle. For reference purposes, side  1  of needle end  12  is the surface directly engaged by upper die  106  and sides  2 ,  3  are the surfaces contacted by coining surfaces  108  of lower dies  104 . 
   With reference again to  FIG. 1 , the next step in the process is a relief grind operation  200 . The relief grind operation removes excess material from needle end  12  and, optionally, may provide a preliminary pointed configuration to the needle end  12 . The removal of needle material from needle end  12  greatly facilitates the subsequent pressing (e.g., bayonet forming), trimming and/or acid etching operations of the process. As best depicted in the top schematic view of  FIG. 3A , the relief grind mechanism  202  of the relief grind operation  200  includes grind wheel  204 . Grind wheel  204  is adapted to rotate about rotational axis “w”. Collet holder  206  secures collet  20  at a predetermined rotational or angular orientation relative to the axis of the collet holder  206  to selectively present any of the sides  1 ,  2 ,  3  to grind wheel  202 . The rotational or angular orientation may be determined by the indexing on the external surface of collet  20 . In addition, collet holder  206  may be arranged at a predetermined positive angle “c” or pitch ( FIG. 3B ) relative to the rotational axis “w” of grind wheel  204  to impart a tapered surface to any of the sides  1 , 2 , 3  of the needle end  12 . In a preferred arrangement, angle “c” ranges from about 50° to about 70°, and, preferably, is about 60° relative to horizontal or transverse plane “t” which intersects the rotational axis “w” of grind wheel  204 .  FIG. 3B  illustrates schematically this pitched arrangement of collet holder  206 , collet  20  and needle end  14  relative to grind wheel  204 . Collet holder  206  is further displaceable in the “x” direction toward grind wheel  204  of the relief grind mechanism. 
   Referring now to  FIG. 3C , collet  20  is initially arranged within collet holder  206  to present side  2  of needle end  12  to grind wheel  204 . In  FIG. 3C , the collet  20  and collet  206  are not shown for clarity purposes. As discussed above, indexing on collet  20  will facilitate obtaining the desired angular or rotational orientation within collet holder  206 . In a first preferred position, collet  20  is placed at an angle “α” to position side  2  in parallel relation (e.g., horizontal) with the rotational axis “w” of grind wheel  204 . For reference purposes, the zero ( 0 ) position of collet  20  corresponds to a horizontal or parallel arrangement of side  1  relative to the axis “w” of the grind wheel  204 . The mechanism  200  is actuated and collet holder  206  is advanced along direction “x” such that grind wheel  204  contacts side  2  of needle end  12 . The grind operation removes a desired amount of needle material from side  2 . Thereafter, collet  20  is arranged at a predetermined angular orientation “−α” (e.g., −60°) within collet holder  206  to present side  3  of needle end  102  to grind wheel  204 . Side  3  is also preferably arranged to be in parallel relation to the rotational axis “w” of grind wheel  202 . The mechanism  200  is actuated to remove a predetermined amount of material from side  3 .  FIG. 3D  depicts an axial view of the configuration of needle end  12  subsequent to the relief grind process. As shown, sides  2 ,  3  generally taper outwardly from end surface  14  towards the rear or main body of needle  10  to define a general pointed or tapered characteristic to needle end  12 . It is appreciated that more or less material may be removed from needle end  12  and that end surface  14  of the needle end  10  may be more or less pointed in configuration. This tapered configuration of needle end  12  is achieved by virtue of the inclined orientation or pitch “c” of collet holder  206  relative to the transverse plane “p” of grind wheel  202 . 
   With reference again to  FIG. 1 , the following step in the process is a press operation which involves forming a bayonet point on the needle end  12  (STEP  300 ). This operation incorporates a press having two lower dies formed to define a cavity for the press operation. With reference to  FIG. 4A , the lower dies, i.e., left and right dies,  302 ,  304  of the press or bayonet form mechanism, each include an angle cut  306  in their upper surfaces which when joined together define a tapered, preferably, triangular-shaped recess  308  in cross-section. Recess  308  gradually decreases in cross-section from front surfaces  302   a ,  304   a  of dies  302 ,  304  to the middle die area where it terminates in point  308   p . The press further includes upper punch  310  which moves to engage needle  10 . Upper punch  310  includes radiused surface  312  having a slight radius of curvature “m”. In one preferred embodiment, the radius of curvature “m” ranges from about 0.250 inches to about 0.500 inches. Preferably, the radius of curvature “m” is about 0.375 inches. 
   In operation, needle end  12  of needle blank  10  is placed within triangular-shaped recess  308  of left and right dies  302 ,  304  with side  1  of the needle end  12  directly opposing radiused surface  312 . With reference to  FIG. 4B , the press is actuated such that upper punch  310  advances to engage needle end  12  thereby swaging the needle end  12  to a general bayonet or triangular shape shown. Surface  1  assumes a slightly curved appearance through its swaging contact with radiused surface  312  of upper punch  310 . Preferably, radiused surface  312  of upper punch  310  contacts the center of the needle end  12  to cause the needle material to more readily splay within recess  308  of the left and right dies  302 ,  304 , i.e., by virtue of the contour of the radiused surface  312 , the radiused surface  312  enters more deeply within the center of recess  308  and into the needle end  12 , which causes the needle material to flow within the recess  308  in a uniform manner. The process, however, also creates an overflow flash “f” on each side of needle end  12  to thereby define the winged appearance shown in in  FIG. 4B . The flash “f” extends radially outwardly from the edges of the needle end  12  generally following the contour of radiused surface  312  of upper punch  310 . The flash material “f” has a thickness “t” adjacent to intersecting edges of sides  1 ,  2 ,  3  of about 0.002 inches. However, by virtue of the previous relief grind operation, the amount of flash “f” generated is substantially reduced as would normally be generated. As indicated hereinabove, this greatly facilitates the remaining operations of the preferred process by removing excess needle material which would otherwise require removal by the forming, trimming and etching operations. 
   Referring now to  FIGS. 5A-5B , the next step in the process is a trim operation (STEP  400 ). The trim operation  400  incorporates two lower dies  402  which are identical to the bayonet forming dies  302 ,  304  of  FIG. 4A . However, dies  402  also incorporate sharp raised protrusions  404  which extend along the perimeter of the recessed areas of each die and the flat remaining surfaces of the dies. The raised protrusion(s)  404  is preferably formed by an (electrode depositing machining EDM) process. The EDM process is coordinated to form a crease line or protrusion  404  adjacent the outer perimeter of the recess. Upon actuation of the press, the raised protrusion  404  forms a corresponding crease and/or perforation in the flash material adjacent location “p” ( FIG. 5B ) to trim the flash along the protrusions  404 . The crease lines eventually become peripheral edges which serve as cutting edges in needle end  12 . The thickness “t” adjacent each crease line is substantially reduced relative to corresponding thickness after the press operation  300 , and may only be about 0.0005 inches thick. As appreciated, excess flash material “f” generated during the press operation  300  may still be present. 
   Referring again to  FIG. 1 , the next step in the process is a second grind operation (step  500 ). The second grind involves lightly grinding the area (e.g., line) of intersection of sides  2 ,  3  of the needle end  12  to reduce some excess flash material which may be adjacent this area and to also form a second point on needle end  12 . The second grind operation may be performed with relief grind mechanism  202  of the relief grind operation  200  discussed hereinabove. In particular, needle blank  10  is arranged within collet holder  206  to present the area or edge connecting sides  2 ,  3  of needle end  14  to grind wheel  204 . The grind mechanism  202  is actuated to grind a minimal amount of needle material from the edge. 
     FIG. 6  depicts in side plan view the configuration of needle end  12  subsequent to the second grind operation  500 . This light grind step also forms a second needle point  18  on the needle end  12 . The second needle point  18  is displaced from the first or distalmost needle point  16  which is created during the press operation  300 . Second needle point  18  eventually defines secondary cutting edges extending from the second needle point  18  to main body  22  of needle blank  10 . The grind surface  24  (i.e., the surface interconnecting the two points  16 ,  18 ) is at a minimal angle “j” preferably about 3° relative to the axis “z” of needle  10 . Preferably, the removed material is only about a few tenths of a thousand of an inch. 
   Referring again to  FIG. 1 , the next step in the process is a flat process operation  600 . The flat press operation  600  includes a gear-activated flat press. The press includes a box die set  602  which is best depicted in  FIG. 7A . The box die is a two component die. One of the die components (e.g., the upper)  604  is movable while the second die component (e.g. the lower)  606  is stationary. The upper die  604  has a flat pressing surface  604   a . The lower die  606  includes a rectangular recess  606   a  having lower pressing surface  608 . Lower pressing surface  608  is arranged at a slight taper or angle to define an angulated punch. The angulated surface tapers upwardly from the front surface of the die set  602  to the rear surface. A preferred angle of taper ranges from about 1° to about 3°, and is preferably about 2°. This arrangement causes a greater or heavier swaging effect adjacent needle end  12  and a lighter swaging effect toward the back end of the needle  10 . Accordingly, the needle material adjacent the needle end  12  splays outwardly to cause a portion of the needle end  12  to be wider than the remaining body  22  of needle blank  10 . In this manner, the cutting edges  4 ,  5  at the intersections of sides  1 ,  2  and sides  1 ,  3  respectively are wider than main body  22  of needle blank  10  and taper back toward the body  22  to define a general spatula-head configuration. 
   In operation, needle blank  10  is placed within rectangular recess  606   a  with side  1  contacting lower surface  608  of lower die  606 . The press is activated. The opposing surfaces of the needle  10  are then pressed whereby the needle material flows to be captured within rectangular recess  606   a . Rectangular recess  606   a  thereby provides a uniform collective pool for the needle  100 . Due to the inclined orientation of lower pressing surface  608 , needle end  12  toward needle point  16  is pressed to a greater extent than the remaining portion or main body  22  of needle  10 . The result of this feature is the formation of a spatula head on the needle end as depicted in  FIG. 7B . The spatula head is characterized by having outer cutting edges  4 ,  5  defined along the respective lines of intersections of surfaces  1 ,  2 , and surfaces  1 ,  3 , which extend beyond the normal periphery of the needle  10  or beyond the edges of the needle body  22 . The main body  22  of needle  10  assumes the rectangular configuration of rectangular recess  606   a .  FIG. 7C  illustrates the cross section of the rectangular configuration of main body  22  of needle  10  after the flat press operation  600 . Preferably, the cross-sectional dimension or needle width “w 1 ” across one surface of the needle is less than the width “w 2 ” across the other surface of the needle. Other configurations are also envisioned. 
   Thus, the aforementioned operations of the preferred process produce a needle having a spatula head configuration as depicted in the views of  FIG. 5B  (with the flash “f” material removed),  FIG. 6 ,  FIG. 7B  and  FIG. 7C . 
   It is envisioned that the aforementioned operations may be adapted to form other needle configurations besides the bayonet or spatula configuration disclosed. These alternate designs may be achieved by appropriate alternate design to the bayonet point form press and/or the trimming/crease forming dies. 
   The next operation is to curve the needle. This step  700  may be formed by any conventional means. In one embodiment, a curving mechanism is utilized to curve the needle body preferably along side  1  of the needle end  12 . One suitable curving mechanism is disclosed in commonly assigned U.S. Pat. No. 5,626,043 to Bogart, the contents of which are incorporated by reference. The curving step  700  is optional. 
   It is envisioned that each of the above processing steps may be performed at one work station, i.e., that each work station or needle manufacturing apparatus may be adapted to perform each of the steps (including coining, grinding and pressing) required to manufacture a single needle in accordance with the preferred process. The parameters of manufacture may be programmed into the work station to control each operation based on needle type, size, etc. Computer programming, software etc., in conjunction with associated computer means, may be incorporated to coordinate the operation of the work station. 
   With reference again to  FIG. 1 , it is also contemplated that a heat treatment operation may be employed to treat the surgical needle to enhance the strength of the needle and its surgical cutting characteristics. The heat treatment operation  800  incorporates a conventional heat treatment oven. The needles are heated in the oven at a sufficient temperature for a sufficient period of time to effectively treat the needle blank(s). The temperature ranges and heating period are in conformance with the material of fabrication of the needle blank, and may be readily determined by one skilled in the art. 
   The next step in the process is a needle etching process  900 . The needle etching process incorporates the step of submerging the surgical needle in an acid bath. The first stage of the etching or acid bath process is a high energy step  1000  where a relatively high amperage current is introduced into the bath of approximately 5-6 amps for about 20-40 seconds, preferably, 30 seconds at 12V-DC. The high energy phase aggressively moves excess flash material from the needle. The second phase in this process is a low energy step  1100  and includes directing relatively low amperage current of approximately 1 amp into the acid bath for about five minutes. This phase produces a matte-like finish on the needle. The needle may then be coated with a suitable coating, e.g. a silicon coating, PTFE coating or Teflon®. 
   It will be understood that various modifications may be made to the embodiments disclosed herein. Therefore, the above description should not be constructed as limiting, but merely as exemplifications of preferred embodiments. Those skilled in the art will envision other modification within the scope and spirit of the claims appended hereto.