Abstract:
An apparatus for cutting a planar medical component having a first surface and a second surface, comprising a clamp for fixing the component and applying a tensile force, a support having a surface having a hole therein, the upper surface disposed proximate the second surface of the component, and a cutting device having a cutting head disposed proximate the support and facing the first surface, wherein the support is configured to move along the plane of the component relative to the clamp and the cutting device cutting head is configured to hold position relative to the support.

Description:
FIELD  
       [0001]     This invention pertains generally to processing flat medical components such as a stent precursor and more specifically to laser processing flat medical components using a support system.  
       BACKGROUND  
       [0002]     Processing of medical components such as stents by laser cutting is known in the art. In some cases, a thin walled tube is laser cut to the desired configuration. In other cases, a flat piece of material such as a metallic material is first cut and then formed into a tubular stent. Stents comprises an interconnected lattice of struts that can expand into a mesh support tube. Processing a stent requires precise, smooth cuts. The present invention provides an improved manufacturing process for manufacturing medical devices such as stents.  
       SUMMARY  
       [0003]     One embodiment pertains to a system for laser processing flat medical components such as stents. The system includes a component to tension the flat medical component such as clamps to hold material, which may be mounted on a linear slide such that tension may be applied to the workpiece, a tensioning device, a cutting nozzle and a center tower support. The center tower support is configured to be under the flat medical component to support it against the forces generated by the cutting nozzle. The center tower support has an upper surface support for supporting the workpiece and a center lumen. The center tower support may also be configured to be used with a fluid such as a lubrication fluid or a cooling fluid. In one such configuration, the center tower support includes an inner support tower having an annular upper surface and an outer support tower having an annular upper surface. The outer support tower and the inner support tower define a second, cylindrical lumen. Fluid may be provided either through the center lumen or the cylindrical lumen and may be evacuated through the other lumen or outwardly. The relative heights of the inner and outer support towers may be adjusted to control fluid flow direction and amount.  
         [0004]     Another embodiment pertains to a center tower support insert that is configured to provide a liquid bearing surface. The insert has an annular, crowned shape that include fluid lumens having exit orifices on the upper surface of the insert. When fluid is provided through these lumens, a liquid bearing surface may be created.  
         [0005]     Another embodiment pertains to an insert where a liquid bearing surface is created by the top surface of a weir in the insert. The weir is defined by an outer and inner wall, which capture the fluid and control the fluid flow direction. The top surface of the fluid in the weir may be used to support the workpiece.  
         [0006]     Another embodiment pertains to a system for laser processing flat medical components where the center tower support and the cutting nozzle are held stationary and the flat medical component is moved laterally along the x-axis and the y-axis.  
         [0007]     Another embodiment pertains to a system where the flat medical component is held stationary and the center tower support and the cutting nozzle are moved. The center tower support and the cutting nozzle may be mechanically synchronized by, for example, mounting them on separate arms of a cantilever.  
         [0008]     Another embodiment pertains to a method of positioning the flat medical component in the clamps. Slits are provided in the component in a direction perpendicular to the direction of the tension. The slits may be positioned at first and second ends of the area of the component to be made into the part.  
         [0009]     It is to be understood that both the foregoing general description and the following detailed description are exemplary, but not restrictive, of the invention. 
     
    
     DESCRIPTION OF DRAWINGS  
       [0010]     The invention is best understood from the following detailed description when read in connection with the accompanying drawing. It is emphasized that, according to common practice, the various features of the drawing are not to scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. Included in the drawing are the following figures:  
         [0011]      FIG. 1  is a plan view of a prior art support system for processing a flat stent.  
         [0012]      FIG. 2  is a plan view of a prior art support system for processing a flat stent with a partially processed stent therein.  
         [0013]      FIG. 3  is top view of a piece of material processed according to a prior art method.  
         [0014]      FIG. 4  is a top view of a piece of material processed according to an embodiment.  
         [0015]      FIG. 5  is an apparatus for processing material according to an embodiment.  
         [0016]      FIG. 6  is a cross-sectional plan view of a center tower support according to an embodiment.  
         [0017]      FIG. 7  is a diagram depicting a method of use of a center tower support.  
         [0018]      FIG. 8  is a diagram depicting a method of use of a center tower support.  
         [0019]      FIG. 9  is a diagram depicting a method of use of a center tower support.  
         [0020]      FIG. 10  is a diagram depicting a method of use of a center tower support.  
         [0021]      FIG. 11  is a cross-sectional view depicting a center tower support in use.  
         [0022]      FIG. 12  is a diagrammatic view depicting an apparatus for processing material.  
         [0023]      FIG. 13  is a cross-sectional view depicting an insert.  
         [0024]      FIG. 14  is a cross-sectional view depicting an insert.  
         [0025]      FIG. 15  is a top view depicting a method of processing material.  
     
    
     DETAILED DESCRIPTION  
       [0026]     The invention will next be illustrated with reference to the figures wherein the same numbers indicate similar elements in all figures. Such figures are intended to be illustrative rather than limiting and are included herewith to facilitate the explanation of the apparatus of the present invention.  
         [0027]      FIG. 1  is a diagrammatic plan view of a prior art support system  100  for processing a flat stent. Support system  100  fixes stent precursor  102  in place for processing. Support system  100  may be a pair of clamps. Processing the stent precursor by laser-cutting and stress relieving the stent precursor, for example, may distort the stent precursor.  FIG. 2 , which is a diagrammatic plan view of a prior art support system  100  with partially processed stent precursor  102  therein, illustrates one issue with this prior technique. The flat material may deflect during processing from the high tension forces of the support system and distort, creating an undesired bump  104 .  FIG. 3 , which is a partial top view of stent precursor  102 , illustrates another issue. The distortion created in the material causes the material to deflect laterally so that the laser does not create the desired geometry. For instance, kerf  106  does not match up with adjacent kerf  108  and the desired effect of removing window  110  is not reached. Further, the struts may be created with an (undesired) non-uniform geometry such as strut  112  being thinner than strut  114 .  
         [0028]     In contrast as illustrated in  FIG. 4 , which is a partial top view of a stent precursor  116  processed according to an embodiment, the struts have a uniform width and all windows have been cleanly removed.  
         [0029]      FIG. 5  is a diagrammatic perspective view of a center tower support system  120 . Workpiece  122 , illustrated in broken lines, is held in place by material holding component  124 . Material holding component may be a pair of clamps, as illustrated, or may be any other mechanism suitable for fixing the workpiece  122  in place. Workpiece  122  may be fixed in tension as desired.  
         [0030]     Center tower support  126  is disposed under the workpiece and includes an upper surface  128  for supporting the workpiece and a central lumen  130 . In this embodiment, the center tower support is disposed on a cantilever arm  132  that may be moved laterally (i.e. along the x-axis and the y-axis) as desired. Alternatively, the center tower support may be disposed on a bridge or other suitable mechanism.  
         [0031]     The center tower support provides several functions, several of which are illustrated here. The center tower support provides support to the workpiece against deflections that may be caused, for example, by gravity or by the cutting action of the cutting instrument. The center tower support may provide a datum that can be used during the cutting process. As discussed below in further detail, the center tower support may be used to provide cooling fluid to the workpiece and to evacuate scrap from the workpiece.  
         [0032]      FIG. 6  is a partial cross-sectional diagrammatic view of center tower support  126 , which consists of inner tower  134  and outer tower  136 . Both inner tower  134  and outer tower  136  are cylindrical and have annular upper surface  138  and  140 , respectively. In alternative embodiments, either or both of the inner and outer towers may have a different shape. For example, outer tower  136  may have an oblong or rectangular cross-sectional shape. In one contemplated embodiment, center tower support comprises a single tower having an annular upper surface. In the embodiment of  FIG. 6 , inner tower  134  defines center lumen  130  and inner tower  134  and outer tower  136  together define an annular lumen  142 . Center lumen  130  may be fluidly attached to a fluid source or an evacuation lumen through bottom lumen  144  or other suitable mechanism. Likewise, annular lumen  142  may be attached to a fluid source or an evacuation lumen through side lumen  146  or other suitable mechanism. Upper surfaces  138  and  140  may be raised or lowered relative to each other to change the profile of the upper support surface. This may be done, for example, to change the amount or direction of the fluid flow, as illustrated below. For example, inner tower  134  may be threadably inserted into support arm  148 , outer tower  136  may be raised or lowered by the insertion or removal of shims or washers, or other suitable mechanisms may be used.  
         [0033]      FIG. 7  is a partial cross-sectional diagrammatic view of center tower support  126  in a particular configuration. Upper surface  140  is positioned proximate to the workpiece  122  and upper surface  138  is positioned at a lower level. Fluid may then be introduced through lumen  146 , up through annular lumen  142  and evacuated down through center lumen  130  and out through lumen  144 , as illustrated by the arrows.  
         [0034]      FIG. 8  is a partial cross-sectional diagrammatic view of center tower support  126  in essentially the same relative configuration as in  FIG. 7 . However, here fluid is introduced through lumen  144  and up through the center lumen. The fluid is then evacuated through lumen  142  and out lumen  146 , as illustrated by the arrows.  
         [0035]      FIG. 9  is a partial cross-sectional diagrammatic view of center tower support  126  in another configuration. Upper surface  138  is positioned slightly away from workpiece  122  and upper surface  140  is positioned at a lower level. As illustrated by the arrows, fluid is introduced through lumen  144  and up through center lumen  130 . The fluid is then evacuated through two paths—down through annular lumen  142  and out lumen  146  and across upper surface  140 . This configuration is an example of a liquid bearing surface where only the liquid is in contact with the workpiece.  
         [0036]      FIG. 10  is a partial cross-sectional diagrammatic view of center tower support  126  in a configuration similar to that of  FIG. 9  but illustrating an alternative flowpath. Fluid is introduced through lumen  146  and up through annular lumen  142 . The fluid is then evacuated through center lumen  130  and outwardly across upper surface  140 . The configurations depicted in  FIGS. 7 through 10  are illustrative and other configurations may be used.  
         [0037]      FIG. 11  is a partial cross-sectional diagrammatic view of center tower support  126  supporting workpiece  122  against the forces from the assist gases from a cutting nozzle  150 . In this configuration, the center tower support permits only a slight bending during the cutting operation. In other configurations, the bending permitted could be lesser or greater. The bending permitted can be adjusted by adjusting the relative heights of inner tower  134  and outer tower  136 , by the presence or absence of fluid flow, and by the amount of fluid flow, for example.  
         [0038]      FIG. 12  is a diagrammatic plan view of a laser-processing system having a workpiece  122  disposed therein. In general operation, the laser cutting nozzle  150  and the center tower support  126  are fixed in position and workpiece  122  is moved during the processing operation. Cutting nozzle  150  is connected to laser source  152 . A center tower support  126  is disposed on a bridge  154 . Bridge  154  is fixed to a stationary object  156  that may be a granite or steel block for dimensional stability. Workpiece  122  is tensioned between clamps  158 , which are fixed to a carriage  160 . Carriage  160  provides for lateral movement along the x-axis and the y-axis. For example, carriage  160  may include a first linear actuator  162  that operates along the x-axis. Actuator  162  is mounted, in turn, on a second linear actuator  164  that operates along the y-axis. Other configurations are possible. For example, carriage  160  may include a rotary actuator as well as the two linear actuators or a rotary actuator and a single linear actuator. The center tower support may be as described above or may be an insert as described below.  
         [0039]     In an alternate embodiment, the laser-processing system may have a fixed workpiece and a movable cutting nozzle and center tower support. The cutting nozzle and center tower support may be mechanically fixed to each other or may merely be synchronized through the electronic controls system. For example, the cutting nozzle may be mounted on one tine of a cantilevered fork and the center tower support may be mounted on another such that the system can provide the nozzle on the opposite side of the workpiece from the center tower support while mechanically ensuring synchronicity.  
         [0040]      FIG. 13  is a partial diagrammatic cross-sectional view of an insert  164  according to the invention. Insert  164  is disposed on bridge  154  and supports a workpiece  122 . Insert  164  may be threadably fastened to bridge  154 . Insert  164  has an annular, crowned upper surface  166 . The cross-sectional profile of upper surface  166  is illustrative and upper surface  166  may have an alternate profile. For example, upper surface  166  may have a flatter profile or it may have a planar ring-shaped surface with rounded inner and outer edges. Insert  164  includes a plurality of fluid delivery lumens  168  that have exit orifices disposed at upper surface  166 . While only two lumens are illustrated in this cross-sectional view, it should be understood that lumens  168  are disposed at intervals about the insert. There may be, for example, 6, 8, 9, 12, or other suitable number of lumens disposed about the insert, each having a fluid exit orifice on upper surface  166 . These lumens may be disposed at regular intervals. When fluid is provided through these lumens, a fluid bearing surface is formed between the upper surface of the insert and the workpiece. The insert may thereby support the workpiece without actually touching it. The fluid is evacuated over the inner and outer edges of the insert. The insert includes a central lumen  130  sized to receive scrap cut from the workpiece. For applications such as cutting stent precursors, a lumen diameter of between about 1 and 5 mm may be desired. Of course, other diameters may be selected as well. The insert may be made from any suitable material, including ceramics, stainless steels, graphalloy, Derin AF, Teflon AF, or sintered ceramics or metals.  
         [0041]     An alternative insert configuration is depicted in  FIG. 14 , which is a partial diagrammatic cross-sectional view thereof. Insert  170  defines a weir  172  that is filled with fluid through lumen  174  to create a liquid bearing surface. Insert  170  includes a central lumen  130  through which scrap and/or fluid may be evacuated. The weir surface is defined by inner wall  176  and outer wall  178 , which may be adjustable or machinable to different heights to direct and optimize the fluid flow. In this configuration, inner wall  176  is slightly lower than outer wall  178  to direct the fluid flow to the center lumen. A needle valve (not depicted) or other suitable mechanism may be used to control the fluid flow and optimize back pressure.  
         [0042]      FIG. 15  is a top diagrammatic view of workpiece  122  in an alternate processing configuration. Workpiece  122  is tensioned between clamps  158  and includes two areas  180  to be formed into parts. Slits  182  are formed in the workpiece normal to the tension force prior to processing. Further, the direction of areas  180  is oriented relative to the tension to minimize deformation. For example, in this embodiment, the part areas are oriented so that the longer dimension is parallel to the tension forces. This processing configuration is suitable for use with any of the systems described herein.  
         [0043]     Those skilled in the art will recognize that the present invention may be manifested in a variety of forms other than the specific embodiments described and contemplated herein. Accordingly, departure in form and detail may be made without departing from the scope and spirit of the present invention as described in the appended claims.