Patent Publication Number: US-9901973-B2

Title: Method and apparatus for creating formed elements used to make wound stents

Description:
RELATED APPLICATIONS 
     This application is a Division of and claims the benefit of U.S. patent application Ser. No. 13/450,309 filed Apr. 18, 2012, now allowed. This disclosures of which are herein incorporated by reference in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention is generally related to an apparatus and method for forming a wave form for a stent. More particularly, the present invention is related to an apparatus and method for forming the wave form from a formable material, such as a wire or a strip of material. 
     Background of the Invention 
     A stent is typically a hollow, generally cylindrical device that is deployed in a body lumen from a radially contracted configuration into a radially expanded configuration, which allows it to contact and support a vessel wall. A plastically deformable stent can be implanted during an angioplasty procedure by using a balloon catheter bearing a compressed or “crimped” stent, which has been loaded onto the balloon. The stent radially expands as the balloon is inflated, forcing the stent into contact with the body lumen, thereby forming a support for the vessel wall. Deployment is effected after the stent has been introduced percutaneously, transported transluminally, and positioned at a desired location by means of the balloon catheter. 
     Stents may be formed from wire(s) or strip(s) of material, may be cut from a tube, or may be cut from a sheet of material and then rolled into a tube-like structure. While some stents may include a plurality of connected rings that are substantially parallel to each other and are oriented substantially perpendicular to a longitudinal axis of the stent, others may include a helical coil that is wrapped or wound around a mandrel aligned with the longitudinal axis at a non-perpendicular angle. 
     Stent designs that are comprised of wound materials generally have complex geometries so that the final stents may be precisely formed. The small size and complexity of some stent designs generally makes its formation difficult. Wound stents are formed such that when unsupported, they create the desired stent pattern and vessel support. This process generally involves winding a source material around a supporting structure such as a rod or mandrel and creating a helical or spring-like wrap pattern. To provide greater support, along this wrapped element, geometries are formed into the source material to better support the tissue in between each wrap, usually of sinusoidal nature. A potential down side to a wrapped stent is that the ends of the stent are generally not perpendicular to the longitudinal axis of the stent, but rather terminate at a pitch angle induced by the helical wrapping. 
     SUMMARY OF THE INVENTION 
     Embodiments of the present invention describe an apparatus and method for forming a wave form for a stent that provides formed geometries that can alter a pitch angle such that the wound stent terminates at a substantially perpendicular angle to the longitudinal axis of the stent. More specifically, the apparatus and method according to embodiments of the present invention allow for the amplitude and wavelength of any individual or half element of the wave form to be manipulated to provide the desired interwrap support. 
     According to an aspect of the present invention, there is provided a method for forming a wave form for a stent. The method includes providing a length of a formable material from a supply of the formable material in a feeder along an axis in a first direction in between a first forming member and a second forming member, the second forming member being positioned closer to the feeder than the first forming member, and moving a first forming portion of the first forming member across the axis in a second direction substantially perpendicular to the first direction to engage and deform the formable material while engaging the formable material with a first forming portion of the second forming member. The method also includes moving the first forming portion of the first forming member and the first forming portion of the second forming member across the axis in a third direction that is substantially opposite the second direction to draw and form the formable material over the first forming portion of the second forming member, disengaging the first forming member from the formable material, and moving the first forming member in a fourth direction substantially perpendicular to the first direction, the second direction, and the third direction. The method also includes moving the first forming member and the second forming member relative to each other so that the first forming member is positioned closer to the feeder than the second forming member, moving a second forming portion of the first forming member into engagement with the formable material, and moving the second forming portion of the first forming member and the first forming portion of the second forming member across the axis in the second direction to draw and form the formable material over the second forming portion of the first forming member. 
     According to an aspect of the present invention, there is provided a forming apparatus configured to form a wave form for a stent out of a formable material. The wave form includes a plurality of substantially straight portions and a plurality of curved portions. The apparatus includes a feeder constructed and arranged to receive a supply of the formable material and to provide the formable material along a feed axis, and a first forming member configured to be movable along three orthogonal axes. The first forming member comprises a first forming portion and a second forming portion having a shape different from the first forming portion. Each of the first forming portion and the second forming portion is configured to engage and deform the formable material. The apparatus also includes a second forming member positioned on an opposite side of the feed axis relative to the first forming member. The second forming member is configured to be movable along the three orthogonal axes and comprises a first forming portion configured to engage and deform the formable material. The apparatus also includes a controller in communication with the feeder, the first forming member, and the second forming member. The controller is configured to control movement of the first and second forming members along the three orthogonal axes to form the wave form. 
     According to an aspect of the present invention, there is provided a method for forming a wave form for a stent. The method includes providing a length of a formable material from a supply of the formable material in a feeder along a feed axis in a first direction in between a first forming member and a second forming member, the second forming member being positioned closer to the feeder than the first forming member, moving a first forming portion of the first forming member into contact with the formable material and across the feed axis in a second direction substantially perpendicular to the first direction, and folding the formable material over a first forming portion of the second forming member by moving the second forming member and the first forming member in a third direction substantially opposite the second direction and moving the second forming member and the first forming member in a fourth direction substantially opposite the first direction. The method also includes disengaging the first forming member from the formable material, moving the first forming member in a fifth direction substantially perpendicular to the first direction, the second direction, the third direction, and the fourth direction, and moving a second forming portion of the first forming member into engagement with the formable material at a position closer to the feeder than the second forming member. The method also includes drawing a length of the formable member from the feeder with the first forming member and the second forming member, and folding the formable material over the second forming portion of the first member by moving the first forming member and the second forming member in the second direction and moving the first forming member and the second forming member in the fourth direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which: 
         FIG. 1  is a schematic top view of an embodiment of a forming apparatus configured to deform a formable material into a desired wave form for a stent, with the formable material being provided in a first direction by a feeder; 
         FIG. 2A  is a schematic side view of an embodiment of a first forming member and a second forming member of the forming apparatus of  FIG. 1 , with the formable material therebetween; 
         FIG. 2B  is a schematic side view of an embodiment of a first forming member and a second forming member of the forming apparatus of  FIG. 1 , with the formable material therebetween; 
         FIG. 2C  is a schematic side view of an embodiment of a first forming member and a second forming member of the forming apparatus of  FIG. 1 , with the formable material therebetween; 
         FIG. 3  is a schematic view of the forming apparatus of  FIG. 1 , with the first forming member being moved in a second direction substantially perpendicular to the first direction to deform the formable material into a half element of the wave form; 
         FIG. 4  is a schematic view of the forming apparatus of  FIG. 3 , with the second forming member and the first forming member being moved in a third direction substantially opposite the second direction to deform the formable material into another half element of the wave form; 
         FIG. 5  is a schematic view of the forming apparatus of  FIG. 4 , with the first forming member being moved away from the formable material and towards the feeder; 
         FIG. 6  is a schematic view of the first forming member being moved upward in a direction perpendicular to a plane in which the first forming member moves in the first direction and the second direction; 
         FIG. 7  is a schematic view of the forming apparatus of  FIG. 5 , with the first forming member, after being moved in the direction illustrated in  FIG. 6 , being moved towards the formable material in the second direction; 
         FIG. 8  is a schematic view of the forming apparatus of  FIG. 7 , with the first forming member and the second forming member being moved in the second direction to deform the formable material into another half element of the wave form; 
         FIG. 9  is a schematic view of the forming apparatus of  FIG. 8 , with the second forming member being moved away from the formable material and towards the feeder; 
         FIG. 10  is a schematic view of the second forming member being moved upward in a direction perpendicular to the plane in which the second forming member moves in the first direction and the second direction; 
         FIG. 11  is a schematic view of the forming apparatus of  FIG. 9 , with the second forming member, after being moved in the direction illustrated in  FIG. 10 , being moved towards the formable material in the third direction; 
         FIG. 12  is a schematic view of the forming apparatus of  FIG. 11 , with the first forming member and the second forming member being moved in the third direction to deform the formable material into another half element of the wave form; 
         FIG. 13  is a schematic view of the forming apparatus of  FIG. 12 , with the first forming member being moved away from the formable material and towards the feeder; 
         FIG. 14  is a schematic view of the first forming member being moved upward in the direction perpendicular to the plane in which the first forming member moves in the first direction and the second direction; 
         FIG. 15  is a schematic view of the forming apparatus of  FIG. 13 , with the first forming member, after being moved in the direction illustrated in  FIG. 14 , being moved towards the formable material in the second direction; 
         FIG. 16  is a schematic view of the forming apparatus of  FIG. 15 , with the first forming member and the second forming member being moved in the second direction to deform the formable material into another half element of the wave form; 
         FIG. 17  is a schematic view of the forming apparatus of  FIG. 16 , with the second forming member being moved away from the formable material and towards the feeder; 
         FIG. 18  is a schematic view of the second forming member being moved upward in the direction perpendicular to the plane in which the second forming member moves in the first direction and the second direction; 
         FIG. 19  is a schematic view of the forming apparatus of  FIG. 17 , with the second forming member, after being moved in the direction illustrated in  FIG. 18 , being moved towards the formable material in the third direction; 
         FIG. 20  is a schematic view of the forming apparatus of  FIG. 19 , with the first forming member and the second forming member being moved in the third direction to deform the formable material into another half element of the wave form; 
         FIG. 21  is a schematic view of the forming apparatus of  FIG. 20 , with the first forming member being moved away from the formable material and towards the feeder; 
         FIG. 22  is a schematic view of the first forming member being moved downward in a direction perpendicular to the plane in which the first forming member moves in the first direction and the second direction; 
         FIG. 23  is a schematic view of the forming apparatus of  FIG. 21 , with the first forming member, after being moved in the direction illustrated in  FIG. 22 , being moved towards the formable material in the second direction; 
         FIG. 24  is a schematic view of the forming apparatus of  FIG. 23 , with the first forming member and the second forming member being moved in the second direction to deform the formable material into another half element of the wave form; 
         FIG. 25  is a schematic view of the forming apparatus of  FIG. 24 , with the second forming member being moved away from the formable material and towards the feeder; 
         FIG. 26  is a schematic view of the second forming member being moved downward in a direction perpendicular to the plane in which the second forming member moves in the first direction and the second direction; 
         FIG. 27  is a schematic view of the forming apparatus of  FIG. 25 , with the second forming member, after being moved in the direction illustrated in  FIG. 26 , being moved towards the formable material in the third direction; 
         FIG. 28  is a schematic view of the forming apparatus of  FIG. 27 , with the first forming member and the second forming member being moved in the third direction to deform the formable material into another half element of the wave form; 
         FIG. 29  is a schematic view of an embodiment of the forming apparatus of  FIG. 1 , with the formable material being provided in the first direction; 
         FIG. 30  is a schematic view of the forming apparatus of  FIG. 29 , with the first forming member being moved in the second direction to deform the formable material; 
         FIG. 31  is a schematic view of the forming apparatus of  FIG. 30 , with the formable material being drawn from the feeder in the first direction by movement of the first forming member and the second forming member; 
         FIG. 32  is a schematic view of the forming apparatus of  FIG. 31 , with the first forming member and the second forming member being moved in the third direction; 
         FIG. 33  is a schematic view of the forming apparatus of  FIG. 32 , with the first forming member and the second forming member being moved in a fourth direction, which is opposite the first direction; 
         FIG. 34  is a schematic view of the forming apparatus of  FIG. 33 , after the first forming member has been moved to a position in between the feeder and the second forming member; 
         FIG. 35  is a schematic view of the forming apparatus of  FIG. 34 , with the formable material being drawn in the first direction by movement of the first forming member and the second forming member; 
         FIG. 36  is a schematic view of the forming apparatus of  FIG. 35 , with the first forming member and the second forming member being moved in the second direction; 
         FIG. 37  is a schematic view of the forming apparatus of  FIG. 36 , with the first forming member and the second forming member being moved in the fourth direction; 
         FIG. 38  illustrates an embodiment of a wave form generated by the forming apparatus of  FIGS. 1-37 ; and 
         FIG. 39  illustrates an embodiment of a wave form generated by the forming apparatus of  FIGS. 1-37 . 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION 
     The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and use of the invention. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description. 
       FIG. 1  schematically illustrates a top view of an embodiment of a forming apparatus  10  that is configured to deform a formable material  12  into a desired shape, i.e. wave form, as discussed in further detail below. The forming apparatus  10  includes a feeder  14  that is constructed and arranged to receive a supply of the formable material and to provide the formable material  12  substantially along a feed axis AX in a first direction FD. The feeder  14  may be configured to actively feed the formable material  12  along the axis AX in the first direction, or may be configured to passively feed the formable material by allowing the formable material  12  to be drawn from the feeder  14 , as discussed in further detail below. The forming apparatus  10  also includes a controller  16  that is configured to communicate with the feeder  14 . The controller  16  may be programmed to provide signals to the feeder  14  so that the feeder  14  feeds the formable material  12  at a desired rate or velocity, and also stops feeding the formable material  12  when desired. 
     The forming apparatus  10  also includes a first forming member  20  and a second forming member  30 . As illustrated in  FIG. 2A , the first forming member  20  includes a first forming portion  22  that may be substantially cylindrical in shape to provide a first engaging surface  23 , a second forming portion  24  that may be substantially cylindrical in shape to provide a second engaging surface  25 , a third forming portion  26  that may be substantially cylindrical in shape to provide a third engaging surface  27 , and a fourth forming portion  28  that may be substantially cylindrical in shape to provide a fourth engaging surface  29 . In the illustrated embodiment, the first forming portion  22  has a diameter that is greater that a diameter of the second forming portion  24 , which is greater than a diameter of the third forming portion  26 , which is greater than a diameter of the fourth forming portion  28 . The different diameters of the forming portions  22 ,  24 ,  26 ,  28  provide the engaging surfaces  23 ,  25 ,  27 ,  29  with different radii of curvature, and are configured to engage the formable material  12  on one side thereof and deform the formable material  12  into a desired shape, as discussed in further detail below. 
     Similar to the first forming member  20 , the second forming member  30  includes a first forming portion  32  that is substantially cylindrical in shape to provide a first engaging surface  33 , a second forming portion  34  that is substantially cylindrical in shape to provide a second engaging surface  35 , a third forming portion  36  that is substantially cylindrical in shape to provide a third engaging surface  37 , and a fourth forming portion  38  that is substantially cylindrical in shape to provide a fourth engaging surface  39 . In the illustrated embodiment, the first forming portion  32  has a diameter that is greater that a diameter of the second forming portion  34 , which is greater than a diameter of the third forming portion  36 , which is greater than a diameter of the fourth forming portion  38 . The different diameters of the forming portions  32 ,  34 ,  36 ,  38  provide the engaging surfaces  33 ,  35 ,  37 ,  39  with different radii of curvature, and are configured to engage the formable material  12  on one side thereof and deform the formable material  12  into a desired shape, as discussed in further detail below. 
     The first engaging member  20  and the second engaging member  30  may include more or less engaging surfaces with different radii of curvatures than illustrated. In an embodiment, each of the first engaging member  20  and the second engaging member  30  may include engaging surfaces that have radii of curvatures. For example, the radius of curvature for each engaging surface described herein may be selected from the group consisting of 0.002″, 0.003″, 0.004″, 0.005″, and 0.006″, or any other desired radius of curvature. 
       FIG. 2B  illustrates an embodiment of a first forming member  20   a  and the second forming member  30   a . As illustrated, the first forming member  20   a  includes a first forming portion  22   a  that has a first engaging surface  23   a  at a distal end thereof, a second forming portion  24   a  that has a second engaging surface  25   a  at a distal end thereof, a third forming portion  26   a  that has a third engaging surface  27   a  at a distal end thereof, and a fourth forming portion  28   a  that has a fourth engaging surface  29   a  at a distal end thereof. The engaging surfaces  23   a ,  25   a ,  27   a ,  29   a  are configured to engage the formable material  12  on one side thereof and deform the formable material  12  into a desired shape, as discussed in further detail below. Each of the forming portions  22   a ,  24   a ,  26   a ,  28   a  may generally be elongated or finger-like in shape, as illustrated, but the illustrated embodiments should not be considered to be limiting in any way. For example, in an embodiment, the first forming member  20   a  may be a single piece of material that is shaped to provide the engaging surfaces  23   a ,  25   a ,  27   a ,  29   a  on one side thereof. Similar to the engaging surfaces  23 ,  25 ,  27 ,  29  illustrated in  FIG. 2A  and described above, each of the engaging surfaces  23   a ,  25   a ,  27   a ,  29   a  has a different radius of curvature. 
     Similarly, the second forming member  30   a  includes a first forming portion  32   a  that has a first engaging surface  33   a  at a distal end thereof, a second forming portion  34   a  that has a second engaging surface  35   a  at a distal end thereof, a third forming portion  36   a  that has a third engaging surface  37   a  at a distal end thereof, and a fourth forming portion  38   a  that has a fourth engaging surface  39   a  at a distal end thereof. The engaging surfaces  33   a ,  35   a ,  37   a ,  39   a  are configured to engage the formable material  12  on one side thereof and deform the formable material  12  into a desired shape, as discussed in further detail below. Each of the forming portions  32   a ,  34   a ,  36   a ,  38   a  may generally be elongated or finger-like in shape, as illustrated, but the illustrated embodiments should not be considered to be limiting in any way. For example, in an embodiment, the second forming member  30   a  may be a single piece of material that is shaped to provide the engaging surfaces  33   a ,  35   a ,  37   a ,  39   a  on one side thereof. Similar to the engaging surfaces  33 ,  35 ,  37 ,  39  illustrated in  FIG. 2A  and described above, each of the engaging surfaces  33   a ,  35   a ,  37   a ,  39   a  has a different radius of curvature. 
       FIG. 2C  illustrates an embodiment of a first forming member  20   b  and a second forming member  30   b  in which respective engaging portions  22   b ,  32   b  having tapered surfaces  23   b ,  33   b  that provide different radii. Other embodiments that provide surfaces having different radii are contemplated and the illustrated embodiment is not intended to be limiting in any way. By way of example only, the embodiment of the first forming member  20  and the second forming member illustrated in  FIG. 2A  will be used throughout the rest of the disclosure with the understanding that the embodiments of the first forming member  20   a ,  20   b , and the second forming member  30   a ,  30   b , which are illustrated in  FIGS. 2B and 2C , as well as other non-illustrated embodiments, may be used in place of the first forming member  20  and the second forming member  30 . 
     As illustrated in  FIG. 1 , the first forming member  20  and the second forming member  30  are positioned so that the second engaging surface  25  of the first forming member  20  and the second engaging surface  35  of the second forming member  30  generally face each other on opposite sides of the formable material  12 . 
     The first forming member  20  and the second forming member  30  may be moved relative to the feeder  14  in an X-Y plane by actuators  40 ,  50 , respectively, that are schematically illustrated in  FIG. 1 . Each of the actuators  40 ,  50  is in communication with the controller  16  so that the controller  16  may send signals to the actuators  40 ,  50  to control movement of the first and second forming members  20 ,  30 , respectively, within the X-Y plane. A suitable motor or actuator  42  that is in communication with the controller  16  may be used to move the first forming member  20  in a Z plane that is substantially perpendicular to the XY plane, and a suitable motor or actuator  52  that is in communication with the controller  16  may be used to move the second forming member  30  in an X-Z plane that is substantially perpendicular to the X-Y plane. In addition, the feeder  14  may be connected to an actuator (not shown) that is in communication with the controller  16  so that the controller may control movement of the feeder  14  relative to the first and second forming members  20 ,  30 . The illustrated embodiment is not intended to be limiting in any way. 
     In operation, the first forming member  20  is initially positioned on one side of the axis AX, and the second forming member  30  is initially positioned on the opposite side of the axis AX relative to the first forming member  20  such that one of the engaging surfaces  23 ,  25 ,  27 ,  29  of the first forming member  20  and one of the engaging surfaces  33 ,  35 ,  37 ,  39  of the second forming member  30  face each other. Although  FIG. 1  illustrates that the second engaging surface  25  of the first forming member  20  and the second engaging surface  35  of the second forming member are initially positioned in the same X-Y plane as the formable material  12 , any of the surfaces  23 ,  25 ,  27 ,  29  of the first forming member  20  and any of the forming surfaces  33 ,  35 ,  37 ,  39  of the second forming member  30  may be initially positioned in the same X-Y plane as the formable material  12 , depending on the desired radius of the first crown to be formed in the wave form. 
     In an embodiment, the controller  16  sends a signal to the feeder  14  to advance the formable material  12  by a predetermined amount or length in the first direction FD substantially along the axis AX. In an embodiment, the feeder  14  does not actively advance the formable material  12 , but instead allows the formable material  12  to be drawn by the first forming member  20  and/or the second forming member  30 , as understood by one of ordinary skill in the art. 
     As illustrated in  FIG. 3 , the first forming member  20  is moved in a second direction SD that is substantially perpendicular to the axis AX so that the second engaging surface  25  engages the formable material  12  and deforms the formable material  12  as the second engaging surface  25  passes over the axis AX. The second forming member  30  may hold its position relative to the axis AX until the first forming member  20  has completed its movement in the second direction SD. 
       FIG. 4  illustrates the second forming member  30  engaging the formable material  12  with the second engaging surface  35  and moving in a third direction TD that is substantially opposite the second direction SD and substantially perpendicular to the axis AX. At the same time or at about the same time, the first forming member  20  also moves with the second forming member  30  in the third direction TD while still engaging the formable material  12 , and the feeder  14  feeds an additional amount of formable material  12  in the first direction FD or the feeder  14  allows the additional amount of formable material  12  to be drawn in the first direction FD. Due to the movement of the first and second forming members  20 ,  30 , the formable material  12  folds over the top of the second elongated portion  34  of the second forming member  30 , as illustrated in  FIG. 4 , to form a half element (i.e., half wavelength) of the wave form. 
     As illustrated in  FIG. 5 , the first forming member  20  then disengages from the formable material  12  and moves away from the formable material  12  in the third direction TD. In addition, the first forming member  20  moves towards the feeder  14  in a direction that is substantially opposite the first direction FD. At the same time, or about the same time, the second forming member  30  moves in the first direction FD as the feeder  14  provides a small amount of formable material  12  in the first direction FD, desirably at about the same rate that the second forming member  30  moves in the first direction FD, to make room for the first forming member  20  in between the feeder  14  and the second forming member  30 . The formable material  12  may be drawn from the feeder  14  or the feeder  14  may actively feed the formable material  12 . 
       FIG. 6  illustrates the movement of the first forming member  20  generally along an axis FPX that is substantially perpendicular to the X-Y plane in which the first forming member  20  moves in the first direction FD, the second direction SD, and the third direction TD. In the illustrated embodiment, the first forming member  20  is moved upward so that another engaging surface, e.g. the third engaging surface  27 , is aligned with the X-Y plane containing the formable material  12 . In an embodiment, the first forming member  20  may be moved downward so that the first engaging surface  23  is substantially aligned with the plane containing the formable material  12 . In other words, the first forming member  20  may be moved in either direction within an X-Z plane that is perpendicular to the X-Y plane so that the engaging surface  23 ,  25 ,  27 ,  29  having the desired radius of curvature may be aligned in the same X-Y plane as the formable material  12 . The illustrated embodiment is not intended to be limiting in any way. 
     The first forming member  20  then moves in the second direction SD towards the formable material  12 , engages the formable material  12  with the third engaging surface  27 , as illustrated in  FIG. 7 , and continues to move in the second direction SD, as illustrated in  FIG. 8 . At the same time, or about the same time, that the third engaging surface  27  of the first forming member  20  moves across the axis AX and to the position illustrated in  FIG. 8 , an additional length of the formable material  12  is provided to accommodate for the distance traveled by the third engaging surface  27  relative to the axis AX, and the second forming member  30  moves at substantially the same speed as the first forming member  20 , in the second direction SD. The additional length may be drawn from the feeder  14  or may be fed by the feeder  14 , as discussed above. 
     Similar to the movement of the first forming member  20  that is represented in  FIG. 5 , the second forming member  30  then moves away from the formable material  12  and away from the axis AX in the second direction SD, and also moves towards the feeder  14  in a direction substantially opposite the first direction, as illustrated in  FIG. 9 . At the same time, or about the same time, the first forming member  20  may move substantially in the first direction FD as a small amount of formable material is provided in the first direction along the axis AX so as to make room for the second forming member  30  in between the feeder  14  and the first forming member  20 . 
       FIG. 10  illustrates the movement of the second forming member  30  generally along an axis SPX that is in an X-Z plane and substantially perpendicular to the X-Y plane in which the second forming member  30  moves in the first direction FD, the second direction SD, and the third direction TD. In the illustrated embodiment, the second forming member  30  is moved upward so that another engaging surface, e.g. the third engaging surface  37 , is aligned with the X-Y plane containing the formable material  12 . In an embodiment, the second forming member  30  may be moved downward so that the first engaging surface  33  is substantially aligned with the X-Y plane containing the formable material  12 . In other words, the second forming member  30  may be moved in either direction within an X-Z plane that is perpendicular to the X-Y plane so that the engaging surface  33 ,  35 ,  37 ,  39  having the desired radius of curvature may be aligned in the same X-Y plane as the formable material  12 . The illustrated embodiment is not intended to be limiting in any way. 
     The second forming member  30  then moves in the third direction TD towards the formable material  12 , as illustrated in  FIG. 11 , engages the formable material  12  with the third engaging surface  37 , and continues to move in the third direction TD, as illustrated in  FIG. 12 . At the same time, or about the same time, that the third engaging surface  37  of the second forming member  30  moves across the axis AX and to the position illustrated in  FIG. 12 , a suitable length of the formable material  12  is provided (i.e. drawn or fed) to accommodate for the distance traveled by the third engaging surface  37  relative to the axis AX. 
     Similar to the movement of the first forming member  20  illustrated in  FIG. 5 , the first forming member  20  then disengages from the formable material  12  and moves away from the formable material in the third direction TD, as illustrated in  FIG. 13 . In addition, the first forming member  20  moves towards the feeder  14  in a direction that is substantially opposite the first direction FD. At the same time, or about the same time, the second forming member  30  may move in the first direction FD as a small amount of formable material  12  is provided in the first direction FD, desirably at about the same rate that the second forming member  30  moves in the first direction FD, to make room for the first forming member  20  in between the feeder  14  and the second forming member  30 . 
       FIG. 14  illustrates movement of the first forming member  20  generally along the axis FPX in an X-Z plane that is substantially perpendicular to the X-Y plane in which the first forming member  20  moves in the first direction FD, the second direction SD, and the third direction TD. In the illustrated embodiment, the first forming member  20  is moved upward so that another engaging surface, e.g. the fourth engaging surface  29 , is aligned with the X-Y plane containing the formable material  12 . In an embodiment, the first forming member  20  may be moved downward so that the first engaging surface  23  or the second engaging surface  25  is substantially aligned with the X-Y plane containing the formable material  12 . In other words, the first forming member  20  may be moved along the axis FPX so that any of the engaging surfaces  23 ,  25 ,  27 ,  29  is aligned in the same X-Y plane as the formable material  12 . The illustrated embodiment is not intended to be limiting in any way. 
     The first forming member  20  then moves in the second direction SD towards the formable material  12 , as illustrated in  FIG. 15 , engages the formable material  12  with the fourth engaging surface  29 , and continues to move in the second direction SD, as illustrated in  FIG. 16 . At the same time, or about the same time, that the fourth engaging surface  29  of the first forming member  20  moves across the axis AX and to the position illustrated in  FIG. 16 , a suitable length of the formable material  12  is provided to accommodate for the distance traveled by the fourth engaging surface  29  relative to the axis AX. 
     Similar to the movement of the second forming member  30  that is represented in  FIG. 9 , the second forming member  30  then moves away from the formable material  12  and away from the axis AX in the second direction SD, and also moves towards the feeder  14  in a direction substantially opposite the first direction FD, as illustrated in  FIG. 17 . At the same time, or about the same time, the first forming member  20  may move substantially in the first direction FD and a small amount of formable material may be provided in the first direction along the axis AX so as to make room for the second forming member  30  in between the feeder  14  and the first forming member  20 . 
       FIG. 18  illustrates the movement of the second forming member  30  generally along the axis SPX. In the illustrated embodiment, the second forming member  30  is moved upward so that another engaging surface, e.g. the fourth engaging surface  39 , is aligned with the X-Y plane containing the formable material  12 . In an embodiment, the second forming member  30  may be moved downward so that the first engaging surface  33  or the second engaging surface  35  is substantially aligned with the X-Y plane containing the formable material  12 . In other words, the second forming member  30  may be moved in either direction along the axis SPX so that any of the engaging surfaces  33 ,  35 ,  37 ,  39  is aligned in the same plane as the formable material  12 . The illustrated embodiment is not intended to be limiting in any way. 
     The second forming member  30  then moves in the third direction TD towards the formable material  12 , as illustrated in  FIG. 19 , engages the formable material  12  with the fourth engaging surface  39 , and continues to move in the third direction TD, as illustrated in  FIG. 20 . At the same time, or about the same time, that the fourth engaging surface  39  of the first forming member  30  moves across the axis AX and to the position illustrated in  FIG. 20 , the feeder  14  feeds a suitable length of the formable material  12  to accommodate for the distance traveled by the fourth engaging surface  39  relative to the axis AX. 
     Similar to the movement of the first forming member  20  illustrated in  FIG. 5 , the first forming member  20  then disengages from the formable material  12  and moves away from the formable material in the third direction TD, as illustrated in  FIG. 21 . In addition, the first forming member  20  moves towards the feeder  14  in a direction that is substantially opposite the first direction FD. At the same time, or about the same time, the second forming member  30  moves in the first direction FD as a small amount of formable material  12  is provided in the first direction, desirably at about the same rate that the second forming member  30  moves in the first direction FD, to make room for the first forming member  20  in between the feeder  14  and the second forming member  30 . 
       FIG. 22  illustrates the movement of the first forming member  20  generally along the axis FPX. In the illustrated embodiment, the first forming member  20  is moved downward so that another engaging surface, e.g. the first engaging surface  23 , is aligned with the X-Y plane containing the formable material  12 . In an embodiment, the first forming member  20  may be moved so that the second engaging surface  25  or the third engaging surface  27  is substantially aligned with the X-Y plane containing the formable material  12 . In other words, the first forming member  20  may be moved in so that any of the engaging surfaces  23 ,  25 ,  27 ,  29  is aligned in the same X-Y plane as the formable material  12 . The illustrated embodiment is not intended to be limiting in any way. 
     The first forming member  20  then moves in the second direction SD towards the formable material  12 , as illustrated in  FIG. 23 , engages the formable material  12  with the first engaging surface  23 , and continues to move in the second direction SD, as illustrated in  FIG. 24 . At the same time, or about the same time, that the first engaging surface  23  of the first forming member  20  moves across the axis AX and to the position illustrated in  FIG. 24 , a suitable length of the formable material  12  is provided to accommodate for the distance traveled by the first engaging surface  23  relative to the axis AX. 
     Similar to the movement of the second forming member  30  that is represented in  FIG. 8 , the second forming member  30  then moves away from the formable material  12  and away from the axis AX in the second direction SD, and also moves towards the feeder  14  in a direction substantially opposite the first direction, as illustrated in  FIG. 25 . At the same time, or about the same time, the first forming member  20  may move substantially in the first direction FD and a small amount of formable material is provided in the first direction along the axis AX so as to make room for the second forming member  30  in between the feeder  14  and the first forming member  20 . 
       FIG. 26  illustrates the movement of the second forming member  30  generally along the axis SPX. In the illustrated embodiment, the second forming member  30  is moved downward so that another engaging surface, e.g. the first engaging surface  33 , is aligned with the X-Y plane containing the formable material  12 . In an embodiment, the second forming member  30  may be moved so that the second engaging surface  35  or the third engaging surface  37  is substantially aligned with the X-Y plane containing the formable material  12 . In other words, the second forming member  30  may be moved so that any of the engaging surfaces  33 ,  35 ,  37 ,  39  is aligned in the same X-Y plane as the formable material  12 . The illustrated embodiment is not intended to be limiting in any way. 
     The second forming member  30  then moves in the third direction TD towards the formable material  12 , as illustrated in  FIG. 27 , engages the formable material  12  with the first engaging surface  33 , and continues to move in the third direction TD, as illustrated in  FIG. 28 . At the same time, or about the same time, that the first engaging surface  33  of the first forming member  30  moves across the axis AX and to the position illustrated in  FIG. 28 , the feeder  14  feeds a suitable length of the formable material  12  to accommodate for the distance traveled by the first engaging surface  33  relative to the axis AX. 
       FIGS. 29-37  illustrate another embodiment of a method of forming a wave form in accordance with another embodiment of the present invention. As illustrated in  FIG. 29 , the method starts with providing a length of the formable material  12  in between the first forming member  20  and the second forming member  30  in the first direction FD.  FIG. 30  illustrates the first forming member  20  being moved in the second direction SD so that the first engaging surface  23  engages the formable material  12  and deforms the formable material  12  while the second forming member  30  remains stationary. 
     As illustrated in  FIG. 31 , the first forming member  20  and the second forming member  30  are moved in the first direction FD so that a length L of the formable material may be drawn out of the feeder  14 . The length L should be greater than or equal to the desired length of next strut of the wave form. As illustrated in  FIG. 32 , the first forming member  20  and the second forming member  30  are moved in the third direction TD as the first engaging surfaces  23 ,  33  engage the formable material  12 . The first forming member  20  and the second forming member  30  are also moved in a fourth direction QD that is opposite the first direction, as illustrated in  FIG. 33 . In an embodiment, rather than the first forming member  20  and the second forming member  30  being moved in the second direction SD and the fourth direction QD sequentially, the first forming member  20  and the second forming member  30  may be moved along an arc or trajectory, as indicated by the dashed line TQD in  FIG. 33 . 
     After the portion of the wave form has been formed, as illustrated in  FIG. 33 , the first forming member  20  is moved in the fourth direction QD to a position that is in between the second forming member  30  and the feeder  14 , as illustrated in  FIG. 34 . In addition, the first forming member  20  may be moved along the axis FPX that is perpendicular to the X-Y plane that contains the formable material  12  so that another engaging surface, such as the second engaging surface  25 , may be positioned in the same X-Y plane as the formable material  12 , as illustrated in  FIG. 6 . With the first forming member  20  in this position, the first forming member  20  and the second forming member  30  may be moved in the first direction FD so that the formable material  12  may be drawn in the first direction by a length L, as illustrated in  FIG. 35 . As before, the length L is greater than or equal to the desired length of the next strut of the wave form. 
       FIG. 36  illustrates the first forming member  20  engaging the formable material  12  with the second engaging surface  25  as the first forming member  20  and the second forming member  30  are moved in the second direction SD. At the same time, or after the first forming member  20  and the second forming member  30  have been moved in the second direction SD, the first forming member  20  and the second forming member  30  are moved in the fourth direction QD, as illustrated in  FIG. 37 .  FIG. 37  also illustrates an arc or trajectory, represented by the line SQD that the first forming member  20  and the second forming member  30  may take instead of the sequential linear movements in the second direction SD and the fourth direction QD. The second forming member  30  may be moved in the fourth direction QD to a position in between the first forming member  20  and the feeder  14 , and the method depicted by  FIGS. 31-37  may be repeated until the desired wave form is formed. 
     The first forming member  20  and the second forming member  30  may be moved away from the wave form being created at any time and moved as illustrated in, for example,  FIGS. 6, 10, 14, 18, 22, and 26 , so that crowns of different radii may be formed. The illustrated embodiments are not intended to be limiting in any way. 
     It has been found that the method of creating the wave form that is illustrated in  FIGS. 31-37  forms struts that may be perfectly straight, or very close to being perfectly straight, and the struts may be formed without being drawn over one of the engaging surfaces. Drawing the formable material over one of the engaging surfaces may create struts in the wave form that may be slightly curved. 
     The steps illustrated in the embodiment of  FIGS. 3-28  may be mixed in with the steps illustrated in the embodiment of  FIGS. 29-37 , as appropriate, in order to achieve the desired wave form. 
     After the apparatus has completed the methods illustrated by  FIGS. 3-28  and  FIGS. 29-37 , a wave form  100  having a plurality of waves including crowns, or curved portions, and substantially straight segments is formed, as illustrated in  FIG. 38 . As illustrated, the wave form includes two crowns  62  that have a first radius, as defined by the first engaging surfaces  23 ,  33 , two crowns  64  that have a second radius, as defined by the second engaging surfaces  25 ,  35 , two crowns  66  that have a third radius, as defined by the third engaging surfaces  27 ,  37 , and two crowns  68  that have a fourth radius, as defined by the fourth engaging surfaces  29 ,  39 . By having forming members  20 ,  30  with engaging portions having engaging surfaces defined by different radii, the radii of the crowns within the wave form  100  may be varied. 
     Although the wave form  100  illustrated in  FIG. 38  includes two crowns having the same radius next to each other along the wave form  100 , the apparatus  10  may be controlled to provide any desired wave form  100  that includes crowns  62 ,  64 ,  66 ,  68  in any order. Also, although four engaging surfaces are illustrated for each forming member, more or less engaging surfaces may be provided. In addition, the lengths of the substantially straight segments may be varied by controlling the movement of the first and second forming members  20 ,  30  in directions perpendicular to the axis AX and/or by providing engaging portions  22 ,  24 ,  26 ,  28 ,  32 ,  34 ,  36 ,  38  having different lengths. For example,  FIG. 39  illustrates a wave form  200  that may be formed by the apparatus  10 . As illustrated, crowns of different radii  62 ,  64 ,  66 ,  68  are more random along the wave form  200 , and the lengths of the substantially straight segments between the crowns are also more random, as compared to the wave form  100  illustrated in  FIG. 38 . 
     The controller  16  may be programmed with the desired wave form and corresponding signals may be communicated to the feeder  14  and the actuators  40 ,  50  that move the first and second forming members  20 ,  30 , so that the first and second forming members  20 ,  30  are moved relative to the feeder  14  and the formable member  12  accordingly. The forming apparatus  10  uses multi-axis motions to deform the formable material  12  and create a specific wave form or stent pattern that creates a stent having substantially perpendicular ends when wound about mandrel or other suitable structure. In an embodiment, the forming apparatus uses a multi-slide to create the multi-axis motions, but it is not necessary to use a multi-slide to create such motions. Other arrangements are contemplated to be within the scope of the invention. In addition, the controller  16  may send corresponding signals to the motors or actuators that provide movement to the first and second forming members  20 ,  30  to change the radii of the crowns and/or the length of the substantially straight segments. 
     The formable material  12  may be a wire or strip material that plastically deforms when deformed by the first and second forming members  20 ,  30  so that the wave form generally holds its shape after being formed. By adjusting the shape and size of the first and second forming members  20 ,  30 , the relative motions of the first and second forming members  20 ,  30  in relation to each other, the formable material  12 , and the feed rate or draw rate and/or movement of the feeder  14 , various amplitudes, periods, and shapes may be created within the wave form to form the overall desired shape for the stent. 
     Embodiments of the stents made using the method and apparatus discussed above may be formed from a wire or a strip of suitable material. In certain embodiments, the stents may be formed, i.e., etched or cut, from a thin tube of suitable material, or from a thin plate of suitable material and rolled into a tube. Suitable materials for the stent include but are not limited to stainless steel, iridium, platinum, gold, tungsten, tantalum, palladium, silver, niobium, zirconium, aluminum, copper, indium, ruthenium, molybdenum, niobium, tin, cobalt, nickel, zinc, iron, gallium, manganese, chromium, titanium, aluminum, vanadium, carbon, and magnesium, as well as combinations, alloys, and/or laminations thereof. For example, the stent may be formed from a cobalt alloy, such as L605 or MP35N®, Nitinol (nickel-titanium shape memory alloy), ABI (palladium-silver alloy), Elgiloy® (cobalt-chromium-nickel alloy), etc. It is also contemplated that the stent may be formed from two or more materials that are laminated together, such as tantalum that is laminated with MP35N® alloy. The stents may also be formed from wires having concentric layers of different metals, alloys, or other materials. Embodiments of the stent may also be formed from hollow tubes, or tubes that have been filled with other materials. The aforementioned materials and laminations are intended to be examples and are not intended to be limiting in any way. 
     While at least one exemplary embodiment has been presented in the foregoing detailed description of the invention, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient roadmap for implementing an exemplary embodiment of the invention, it being understood that various changes may be made in the function and arrangement of members described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims.