Abstract:
A coating apparatus and method for flimsy elongate members has at least one elongate funnel tube with an inlet, an outlet, and an intermediate portion, the inlet in a basin, a fluid circulating system suitable connecting the outlet to provide flow into the inlet. Each inlet receives an elongate flimsy component and utilizes the circulating fluid to pull the flimsy elongate member into the funnel tube whereby the coating of the flimsy elongate member is accomplished. The invention also includes the method for coating such a flimsy elongate member utilizing the coating apparatus.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Application Ser. No. 60/784,181, filed Mar. 21, 2006 and U.S. Provisional Application Ser. No. 60/784,173, filed Mar. 21, 2006. Both of these applications are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to coating equipment, more precisely the invention relates to a method and apparatus for providing coatings on elongate flimsy members that are manufactured into medical devices such as catheters and guide wires. 
       BACKGROUND OF THE INVENTION 
       [0003]    Many medical devices utilize elongate flimsy members that are advantageously coated with various coating including biological coatings. Examples of one of these could be either guide wires or catheters. These items are often up to 100 inches in length and may have a diameter of less than 0.030 inches in diameter. A simple way to coat these flimsy elongate members is to dip them into a solution and then draw them out at a controlled rate. Often, especially for biological coatings, the coating material is so expensive and has such a limited pot life that mixing a large tank of material to dip the device into is cost prohibitive. The standard industry practice is to fill funnel tube with the coating material that is not much larger in diameter than the item to be coated to minimize the volume of fluid. A common funnel tube has an inner diameter of 0.375 inches. A “flimsy” elongate member can, for example, be defined as a member that cannot resist a force of 0.1 pound applied upwardly to the bottom of the member. The flimsy member will buckle rather than resist the force. 
         [0004]    There are two basic problems that come up when you try to dip these flimsy elongate members into a funnel tube of coating material. The first problem is the initial insertion of the flimsy elongate member into the funnel tube. The surface tension and the viscosity of the fluid apply oppose the insertion force which can initiate a buckling of the flimsy elongate member. If the buckling is excessive the flexible elongate component will not be urged into the tube and/or the flexible elongate component could be damaged. It is very common for the coating materials to be very viscous(&gt;50 centipose) and have a high surface tension. The most common way to get around this issue is to insert the flimsy elongate member into the funnel tube at a very slow rate (&lt;2 inches/sec) that may allow some level of buckling while the tubing is being inserted. The problem with a very slow dipping rate is that it is slows down the production of these devices to such a slow rate that it is not practical to do this. The problem with allowing some buckling is that it is not very consistent from device to device making it very hard to automate and requiring human intervention. 
         [0005]    When inserting these flimsy elongate members into the funnel tube filled with viscous fluid, it is common for the flimsy elongate member to come into contact with the sides of the funnel tube. When the inserted flimsy elongate member does contact the side of the tubing it&#39;d resistance to being inserted into the funnel tube may increase making it more likely to buckle the flimsy elongate member. 
       SUMMARY OF THE INVENTION 
       [0006]    In certain embodiments, a coating apparatus for flimsy elongate members has an elongate coating tube with a funnel shaped inlet portion, an outlet portion, and an intermediate portion, the inlet extending upwardly in a basin, a fluid circulating system connecting the outlet to the basin whereby fluid from the basin flows into the inlet. The inlet also receives the elongate flimsy component and utilizes the circulating fluid to pull the flimsy elongate member into the intermediate portion of the funnel tube whereby the coating of the flimsy elongate member is accomplished. In certain embodiments, a vortex may be created at the inlet portion. Multiple funnel tubes by be utilized the method for coating such a flimsy elongate member utilizing the coating apparatus. 
         [0007]    An advantage and feature of certain embodiments of the invention is that the reliability and speed that an automated coating system can process these components is increased. The insertion speed of the elongate flimsy component into the funnel tube is greatly increased. 
         [0008]    Another advantage of certain embodiments of the invention is that it allows the flimsy elongate members to be inserted into a small diameter tube filled with fluid without buckling or at much greater rate of insertion without buckling. 
         [0009]    Another advantage and feature of certain embodiments is that the feeding mechanism of the elongate flimsy components is simplified and reduced by minimizing the handling difficulty and complexity of the handling mechanisms above the funnel tube. Additional handling apparatus would generally be needed for the insertion motion where the fluid assist is not present. 
         [0010]    Another advantage and feature of certain embodiments of the invention is that a plurality or multiplicity of the funnel tubes can be utilized in the basin with the single fluid circulation system providing for batch processing of a large number of elongate flimsy members at one time. This invention allows a medical company manufacturing the devices to maximize its throughput and minimize their costs for coating these devices 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a schematic illustration of an embodiment of the apparatus. 
           [0012]      FIG. 2  is a perspective-schematic view of an embodiment illustrating a basin according to the invention herein. 
           [0013]      FIG. 3  is a perspective-schematic view of an embodiment illustrating a basin according to the invention herein. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0014]      FIG. 1  shows an example of the flow directed feeding system  100  for a single funnel tube. A suspension system  106  having support structure  108 , a carriage  110  vertically movable with respect to the support structure, and a drive system  120  for moving the carriage. The carriage has a securement portion  130  configured as a clamping device, for example a collet, for securing a first end  136  of the elongate flimsy member  140 . A second end  142  and an intermediate portion  144  of the secured elongate flimsy member dangle downwardly therefrom. The carriage moves vertically, as indicated by the arrow  143  for lowering and withdrawing the flimsy elongate member  140  with respect to the fluid circulating system  145  and more specifically the coating tube  160  configured as a funnel tube. The fluid circulating system has the basin  166  or shallow tank with coating fluid F therein. The coating tube  160  has an inlet portion  170  configured as a funnel disposed in the basin and preferably facing upward. The funnel portion has an upper lip  171  over which the fluid in the basin will flow. The coating tube  160  also has an outlet portion  191  with an intermediate portion  192 . The funnel tube outlet portion connects to an adjustable flow control valve  193  and leads to a reservoir  195 . A circulating pump  197  pumps fluid from the reservoir into the basin. An over flow tube  199  may be utilized to keep the fluid in the basin at a desired level. 
         [0015]    When used herein, “portion” can be a discrete part, a combination of a plurality of discrete parts assembled, or an integral portion of a component to which it is part. “Connected”, “connecting”, and the like do not require direct connection or contact and can have intermediate linking components. 
         [0016]    The apparatus operates as follows. First, sufficient fluid in put in the fluid circulating system for plenishing the reservoir, the funnel tube and basin to a desired level. The pump  197  pumps the fluid F from the lower reservoir  195  into the upper reservoir or basin  166 . When the fluid level  205  is above the top of the funnel tube  160  it begins to flow down the funnel tube. The flow rate of the pump  197  is preferably greater than the flow down the funnel tube  160  so the level in the upper reservoir  166  increases until it reaches the overflow tube  199  at which point the fluid levels. The flow control value  193  is adjusted to (manually or automatically) to get the fluid to flow down the funnel tube with the right velocity, preferably creating a small vortex  208  at the inlet portion  170  to the funnel tube  160 . With the fluid now flowing into the coating tubing  160 , a flimsy elongate member can be drawn down and pulled by the fluid into the tube filled with liquid. Once the flimsy elongate member  140  is completely inserted into the tube  160 , the flow control valve  193  can be closed and/or the pump shut down. Then the flimsy elongate member  140  will be drawn out of the fluid by the carriage  110  at a controlled suitable rate. This allows the flimsy elongate member  140  to be uniformly coated by the fluid. The level of the liquid in the basin could be controlled by other techniques other than an overflow tube. 
         [0017]    Referring to  FIG. 2 , an example of multiple fluid flow arrangement includes a basin  220  with a plurality of funnel tube inlets  224  that connect to a fluid reservoir  231  through funnel tube outlet lines  233 . A pump  227  circulates fluid back to the basin through inlet lines  240  into basin inlets  242 . Control valves  244  may be placed in the inlet lines for regulating flow into the basin. Such valve may be adjustable to provide suitable flow into the individual funnel tube inlets. Similarly, further control valves  250  may be placed in the funnel tube outlet lines  233 . Fluid conditioning equipment such as agitators  252 , heaters  254 , filters  256 , and the like may be incorporated as appropriate. A control processor  262  may be utilized to operate the valves and pump and conditioning equipment as well as monitoring the process through various sensors. 
         [0018]    Referring to  FIG. 3 , an alternative arrangement is illustrated where individual flow lines  366  for each funnel tube inlet are provided with valve controls  344 . In this embodiment, the basin may not be required or may be used as an overflow collection basin. 
         [0019]    Referring to  FIGS. 2 and 3 , means for adjusting the inlet flow of the fluid into the funnel tube inlets for creating suitable inlet flow, such as vortexes, includes the control valves  250 ,  344 . Additionally, barriers  256  can be installed, preferably removable, in the basin for tweaking individual inlet flows. Such means for adjusting inlet flow into the funnel tubes can provide the adjustment needed when different coating fluids are utilized with the basin. Such different coating fluids will typically have different flow characteristics requiring some adjustment to obtain ideal fluid flow, such as vortexes in the funnel tube inlets. Various methods can be come with to control the flow of the liquid through the system as part of the means for adjusting the inlet flow including multiple and variable flow pumps. The fluid circulation can have provisions for circulating, for example sequentially, different fluids for step coating of the elongate flimsy member. Also, the fluid utilized during the initial circulation when the elongate flimsy member is drawn into the coating tube does not have to be the ultimate coating fluid utilized for coating the drawn-in elongate flimsy member. 
         [0020]    The carriage or controlled motion axis can be made out of any number of computer controlled devices (pc, PLC, motion card, amplifier, power supply, servo motor, stepper, etc.) and the actual motion can be made by many types of drives  120  (belt drive, ball screw, linear motor, etc.). 
         [0021]    This invention provides coating of flimsy elongate members in large batches, insertion of the members into a fluid reservoir at a high rate of speed and with great reliability. Typically, the devices being coated are used in the medical industry and are components commonly referred to as guide wires, and catheters. 
         [0022]    The above embodiments are intended to be illustrative and not limiting. Additional embodiments are within the claims. Although the present invention has been described with reference to particular embodiments, workers skilled in the art will recognize that changes may be made in form in detail with departing from the spirit and scope of the invention.