DESCRIPTION
PROFILING DIE
Technical Field
This invention relates to a profiling die which is useful to finish or size a profile extruded tubular plastic material, such as a tubular length for use in a catheter.
Background of the Invention
This invention is of a mold or die for use in finishing tubular material of plastic and, by way of particular example, tube lengths for use as angio- graphic catheters. It will be appreciated that it is important that such tubular lengths have resistance to torsion so that the distal end responds as closely as possible to rotation at the proximal end. Further, it is important to have a catheter which is capable of delivering a relatively large volume, that is, one which has as thin a wall as possible so as to present a lumen of maximum diameter which is strong and smooth on the interior and yet which has the other qualities herein discussed. -It is further important that such a tubular length do not promote clotting within the time of a normal medical procedure. As is appreciated, in use catheters are inserted axially into a tubular shaped zone of the body and a catheter should, therefore, be sufficiently stiff so as not to buckle under axial pressure and also be characterized by what is often termed as lubriscity. Additionally, the"catheter "when deformed "should have a memory capacity so as to return to the correct shape after being straightened by a guide wire during positioning of the catheter. Also, a low coefficient of friction between the inside of the catheter and the guide wire as well as between the outside surface of the catheter at the entrance site and the body, termed lubriscity, is important. Generally speaking in making tube
lengths for angiographic catheters, as well as other type tube lengths, it is desirable to have a smoothly finished accurately made product.
This invention is of a mold or die for use in making a catheter with such characteristics including a high tensil flexible plastic such as one of a material from the nylon family which may be covered by another biocompatible like urethanes properly treated to decrease the high coefficient of friction. The present invention provides a die or mold whereby
10 a substantially larger lumen for a tube length may be produced without sacrificing the other characteris¬ tics set forth above. It will be understood by those in the art that this tool is useful in extruding such materials as are used in the art for such catheters , _- which may have a radial opaque ingredient.
Summary of the Invention:
Generally speaking, this invention is of a die for making catheters, or tubular lengths for cathe-
20 ters, having improved surface finish characteristics, i.e., lubriscity, and wherein the size thereof can be controlled in a manufacturing process of extruding
•-'•;."-'-' thermopl sti'c'-round."shapes.: "Therinvention" is of "a "~" die preferably made of brass which in use is heated
- - to an appropriate "temperature below the melting point of the plastic being treated and above the deforma¬ tion temperature and wherein there is a through passageway with a stepped cylindrical cavity with an intermediate conical section in which a piece of
30 Teflon material of predetermined form and which is of " 'integral" molded form is disposed".' '■' The: die preferably includes a plug so that it can be used directly in front of the extruder. The instant invention while : described in. one embodiment. can.be used for forming. .
35 different profiles for catheter tubes which will give a better surface than grinding and using solvents and other coatings and also has the added advantage of being more economical and more manipulative in use.
OM WIP
The invention is for use in a process of forming inside and outside profiles for catheter lengths and includes the forming die with an interior cavity with the outside profile desired covered by a preformed Teflon shrink tubing with the required heat and tip desired and a stainless steel portion. The procedure is to insert a mandrel into the cavity as is well known in the art so that plastic may be passed through the die and the mandrel may be withdrawn from the other side of the die. It will be seen that upon axial movement into the larger bore, the leading end of the tubular length of slightly less diameter will be guided by the Teflon lined tapered or conical surface to the diameter of the Teflon lined smaller bore size, i.e., the outside diameter of the tube being formed will be intercepted by the annular face of the conical Teflon portion presented to it and, in the process described of using the die, after passage through the heated zone of the die, which includes the Teflon lined zone, including the cylindrical length to which it is constrained and constricted, the outside diameter of the tube will be somewhat smaller after passage from one end of the forming die to the other end. --' ....... -........-..-
Objects of the Invention:
It is, accordingly, an object of this invention to provide an improved tool for use in making tubular lengths of plastic material.
In accordance with this principal object, and other principal objects, the instant invention will how be"described'with "reference tb-'the accompanying drawings, in which:
Description of the Drawings: Figure 1 is the end view of a mold constructed in accordance with the instant invention;
Figure 2 is a view in cross section taken on the plane indicated by the line 2-2 of Figure 1 and
looking in the direction of the arrows.
Description of the Preferred Embodiment:
Referring to the drawings wherein like reference characters designate like or corresponding parts throughout the several views, and referring parti¬ cularly to Figure 2, there is shown a mold 14 having a body 20 with an end face 18 and an opposite end face and an axially extending annular surface 16 which is jacketed by a conventional heater means 15,
10 such as an electrical resistance coil. In the mold body there is a first axial bore 22 of predetermined size extending from one end face and from the other end face 18 a second coaxial threaded bore of a larger diameter than that of the first mentioned
15 bore. Between the inner end of these two bores there is a coaxial tapered section 24. Preferably, within the bore 26 in the end face 18, a threaded plug 28 is provided with a tapered inner end. As shown, the tapered section has an outwardly flared shoulder at
20 the plug bore; and this seats the tapered inner end 30 of the plug. This annular outer face of the plug may be provided with a cutout 28' for a screwdriver - or the.like
it to captivate the Teflon ' insert.
^t- Within the passageway thus defined, a molded
Teflon member which is integral is inserted; and its end 36 is .captivated in place as shown by the plug in the preferred embodiment. Teflon is the trademark of a well known commercially available product of the
3Q E.I. duPont de Nemenours Company of Wilmington, .': Delaware":' ~ This" eflo "insert has a "tapered end zone indicated by the numeral 38 to line along the tapered section 24 and an outwardly flared terminal end zone . . . 36 to.dwell.oh the. shoulder, to be held by the end
35 face 30 of the plug 28. The member has an axially extending zone 32 terminating at a tip 34, which is exterior of the die as shown; and the tip 34 is outwardly flared somewhat to smoothly or gradually
OMP WIP
break away from or depart from a plastic length on a mandrel being pulled axially from the right side of Figure 2 to and out the left side of Figure 2.
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