MXPA98000180A - Procedure of molding and cut of tip of cate - Google Patents

Abstract

The present invention relates to a method for forming an intravenous catheter, characterized in that it comprises the steps of: a) mounting a tubular catheter on a mandrel, with the mandrel extending beyond a distal end of the catheter, b) heating a mold having a tapered internal mold surface that includes an area defining a desired catheter tip, c) inserting the catheter and mandrel into the mold to couple the catheter to the internal mold surface, d) allowing the catheter to soften and conform to the internal mold surface in said area to form the tip of the catheter and form a burr that extends beyond the tip of the catheter of the mold, e) remove the catheter with the tip of the catheter and burr, and the mandrel of the mold and the mandrel of catheter, f) then inserting the catheter into a guide having a cutting surface defining an opening, so that the burr extends through the opening beyond the opening of the catheter. cutting) g) moving a cutter along said cutting surface to cut the burr extending beyond said cutting surface of the catheter, to form a cut-off catheter having a tip, h) removing the trimmed catheter the gu

Description

MOLDING PROCEDURE AND CUTTING OF CATHETER FIELD OF THE INVENTION The invention relates to a method for forming medical devices and to a method for forming catheters with a tapered tip.

BACKGROUND OF THE INVENTION It has long been known to smoke the tip of a catheter- / in particular an intravenous catheter peripherally inserted to facilitate the insertion process. It has also been found, and many products currently have it, a double bevel formed at the tip of the catheter. The first bevel is a taper of approximately 3rd and the second bevel is an abatement of approximately 27 °. These tips can be formed, for example, by cutting with l, as shown in the patent of E.U.fl. No. 5,425,903 or by molding as shown in the U.S. Patent. No. 4,661,300 from Daugherty. The Daugherty patent shows a molding process in which a one-step orientation is used to form and hold the catheter. That is, the catheter is placed on a mandrel with the catheter material extending beyond the mandrel and this assembly then inserted into a heated rim for forming the outer surface of the catheter. The mandrel is advanced to a point where it engages the surface of the rnolde to hold the burr of the catheter in a single pass. However, the one-step process has significant disadvantages in that it provides a short tool life since the tool and the mandrel are used as cutting devices and therefore must be coupled and wear each other out. That means that, during use, the outer surface formed on the catheter varies as the con + act between the mandrel and the die wears the internal surface of the die. In addition, the tool must be replaced to maintain a sharp edge on the mandrel to provide proper cutting action.

BRIEF DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a tip on an intravenous catheter including the steps of mounting a tubular catheter on a mandrel, said mandrel extending beyond the end of the catheter or proposed tip area. A rnolde having a tapered internal rnolde surface that is complemented with the desired outer surface of the finished catheter is heated and the catheter-carrying mandrel is inserted into the mold to couple the catheter material with the internal surface of the mold. The coupling of the catheter material with the inner surface of the head makes the catheter material soften and conform to the inner surface of the head and form a burr extending beyond the desired catheter tip. The catheter and mandrel are removed from the mold after the material has had a chance to cool and then the mandrel is removed from the catheter. Alternatively, this can be done as a single step by removing the mandrel from the catheter and then removing the catheter from the hub. In a second operation, the catheter with attached burr is inserted into a guide having a cutting surface defining an opening. The insertion of the catheter into the guide allows the burr to extend through the opening beyond the cutting surface. A cutter moves along the cutting surface and cuts the burr that extends above the surface and separates that burr from the rest of the catheter. This forms a cut catheter that is subsequently removed from the guide for further processing. The guide can be formed to define a passage that ends at the desired opening. The passage may be complementary to the outer surface of the catheter for ease of placement of the catheter with the burr extending at an appropriate distance. The cutter can be a single blade or double blade such as a razor blade in a manual operation. The blade may preferably be around the. 0076 crn to approximately. 025 cm thick and the catheter may be formed of a material such as a polyethylene (PTFE) or polyurethane.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described with reference to the accompanying drawings in which: Figure 1 is an illustration of the molding process of the present invention; and Figure 2 is an illustration of the cutting guide and cutting procedure of the present invention.

DESCRIPTION OF THE PREFERRED MODALITIES The present invention refers to a simplified and precise method for forming catheter tips. In particular, in the formation of tapered catheter tips it is necessary to form the taper and remove any burrs that may form. In the present method, a tubular catheter 1 made, for example, of either polytetrafluoroethylene or polyurethane is placed on a concentric mandrel 2. The mandrel 2 is received within the internal hole 3 of the catheter cannula and extends beyond the catheter. end 5 of the catheter. A rnolde 6 is provided having a tapered inner surface 7 which is complementary to the desired external surface of the final catheter. For example, it may be preferred that a shallow taper of about 3o along a certain length of the catheter is provided and a more acute bevel is provided at the tip of the catheter for example 27 ° to stretch the surface of the catheter to where it will find a needle cannula that passes through the internal hole of the catheter. The rnolde is heated to an appropriate temperature to soften the catheter material. For example, for a 20 gauge polytetrafluoroethylene catheter (ie, .114 crn in diameter) this temperature is around 343.3 ° C to about 398.8 ° C. The catheter 1 and the mandrel 2 are inserted into the hub 6 in a known manner to couple the catheter material to the surface of the heated rnolde. The catheter material heats up and softens and begins to flow into the space within the rim that surrounds the mandrel. A portion of the catheter material flows out of the desired ridge area to form a burr tip 8. It should be noted that the mandrel 2 of the present procedure passes beyond the tip of the burr to support it in such a manner that the cooling a cylindrical piece of burr 0 extends beyond the desired tip of the catheter. This burr 8 will subsequently be removed and extended in such a way that it will provide consistent filling of the mold as well as a consistent portion that must be removed by the secondary cutting procedure.

The roller 6 and the catheter 1 are allowed to cool, after which the catheter 1 and the mandrel 2 are removed from the internal mold passage. The mandrel is removed after the inside of the catheter and the catheter is inserted into the female guide 9 (Figure 2). The female guide 9 has a defined opening 10 through which it complements the desired external surface of the final catheter. This opening 10 terminates in an upper cutting surface 11 which is located with respect to the opening precisely where it is desired to cut the catheter. fll insert the catheter 1 into this opening, the burr 8 extends beyond the cutting surface 11 and is exposed outside the guide. A cutting blade subsequently runs along the cutting surface 11 to cut the burr 8 and remove it from the end of the catheter tube. The cutting blade 11 should be as thin as consistent with sufficient strength to cut the catheter material in order to avoid squashing the catheter on it even during the cutting procedure. It will easily be seen that a thick or heavy cutting edge over the passage along the cutting surface would tend to crush the initial side with which the blade contacts the opposite side thereby deforming the catheter and the last cut. The burr is thus removed from the tip of the catheter 1 and the catheter is removed from guide 9 for further processing. The invention has been described in connection with the accompanying drawings and their preferred embodiments. Minor changes can be made to the invention without exceeding the scope of the invention contemplated.

Claims (7)

NOVELTY OF THE INVENTION CLAIMS

1. A method for forming a tip on an intravenous catheter comprising the steps of: a) mounting a tubular catheter on a mandrel with the mandrel extending beyond the catheter; b) heating a mold having a tapered internal mold surface; c) Insert the catheter and mandrel into the hub to attach the catheter material to the inner surface of the hub; d) allowing the catheter material to soften and conform to the inner surface of the head forming a flash that extends beyond the desired catheter tip; e) remove the catheter and the mandrel from the rnolde and the catheter mandrel; f) inserting the catheter into a guide having a cutting surface defining an opening such that the burr extends through the opening beyond the cutting surface; g) moving a cutter along said cutting surface to cut the burr extending above said surface of the rest of the catheter to form a cut catheter; and h) remove the cut catheter from the guide.

2. The method according to claim 1, further characterized in that said guide defines a passage that is in the opening, said passage complementing the outer surface of the catheter to precisely locate the catheter to cut it.

3. The method according to claim 1, further characterized in that the cutter is a single or multiple blade.

4. The process according to claim 3, further characterized in that the blade is about .0076 crn to about .025 crn in thickness.

5. The method according to claim 1, further characterized in that said cutter comprises a shaving hoe which is manually continued along the surface to cut the burr.

6. The method according to claim 1, further characterized in that the catheter is made of polytetrafluoroethylene material and the rnolde is heated from about 343.3 ° C to 398.8 ° C. ? . - The method according to claim 1, further characterized in that the catheter is formed of polyurethane material and said rnolde is heated from about 232.2 ° C to 287.7 ° C.