DE2223603A1 - Joining two plastics components of a medical device - - using intermediate metal part between components and then melt form - Google Patents

Abstract

Process for joining two separate components of a medical device (e.g. a catheter) consisting of similar plastics material, is characterised by shaping the components to be joined in such a way that they fit in to each other; placing a metal part between the fitted components; placing the whole into an induction heating device; applying heat of induction to the ends of the components and the metal part so as to heat same and soften the overlapping ends; removing the components from the heating device; and cooling so as to effect a medically acceptable joint.

Description

Method and arrangement for joining two plastic parts of a medical device The invention relates to a fixed connection between two Parts of a medical device made of similar plastic and a method for Establishing such a connection. This is achieved by inserting a corresponding metal part between nested or overlapping End sections of the plastic parts. The area of the connection you want will be then used in an induction generator, in which by applying electricity the metal part generates so much heat that the surrounding plastic softens will. A results in slight pressure in the connection area when cooling a permanent connection. According to a modification, the metal part is made of plastic covered, of a contrasting color and a higher melting point than that Has parts made of similar Kunstatoff, so that the induction heat the plastic of the parts but not the plastic cover of the metal part melts, and after as the parts are connected to each other, the color of the metal part increases Identification purposes (color coding) but shines through.

In the field of medicine, those of members of this profession must The instruments used meet the highest possible requirements. This is particular then the case when instruments are used for inspection or inspection during surgery of body fluids, in the postoperative drainage of fluids and the like.

be used as when an instrument is critical during this Process fails, part of the instrument remains in the patient's body, so that the patient may be lost, or significant complications occur in recovery.

In particular, plastic catheters are being used on a large scale at used all kinds of prevention, healing and diagnosis by patients. These Catheters are often designed in two parts, which are firmly connected to one another Need to become. Failure of this connection leads to the occurrence of complications. For example, in one type of catheter, the elongated body of the catheter is included connected to a plastic hub, which has a Baåonettenverriegelung for releasable connection an external source of suction or a source of liquid, e.g. blood plasma or the like. Contains. A failure of the connection can cause the main part of the catheter remains in the patient or usable fluid is lost.

Until now, different types of adhesives, solvents, Pressure welding, ultrasound, metal clamping bands or the like. Used around the plastic parts of medical devices to connect to each other, but these connections are either not one hundred percent secure, or they are very expensive, or both.

Recently, there has been a method using induction heating a plastic insert tested, which contains powdered metal particles, where the Insert was inserted between the two parts, and although there was a very favorable connection, it was medically unacceptable, because flakes of the powdered metal came out into the surface of the catheter and contaminated the catheter and made it unusable.

It is accordingly the underlying object of the invention, this To avoid shortcomings of the known connecting arrangements that are used to connect two parts of a medical device were used and a good, cheap one and medically sound connection and a method for using it hu create in medical devices.

According to a preferred white embodiment of the invention, a medical Device, e.g. a catheter, a body and a hub, both of which are similar to one another Consist of plastic material, with the sections to be connected to form are that they are inside or on top of each other. A solid metal insert, e.g.

a ring, with ferromagnetic and / or heat induction properties is inserted between the nested or overlapping parts and the the insert part containing area of the device is turned into a controlled Beld used an induction heating generator, whereupon the nested or overlapping plastic parts are softened to the melting point. The melted Parts flow into each other and after being removed from the generator field they cool down Part and form a solid connection that is acceptable for medical purposes is.

The invention is illustrated below with reference to the drawings Exemplary embodiments explained in more detail: In the drawings: FIG. 1 shows a side view a medical device which has a plastic hub and a cannula that According to the invention, FIG. 2 shows a needle for use in the device according to Fig. 1, Fig. 3 on an enlarged scale a longitudinal section through the overlapping Parts and the connection established between them, Fig. 4 a disassembled view of the parts according to FIG. 3, FIG. 5 shows a view of another embodiment of the interlocking parts that form a field winding of an induction heating generator 6 is a view of the shape of the interlocking parts according to FIG. 5, the parts being firmly connected to one another, and FIG. 7 a longitudinal part by another medical device using the improved compound according to the invention.

In the preferred embodiments shown in the drawings the same reference characters are used for the same parts in all views, in particular Fig. 1 to 4 inclusive, which show a medical device, i.e. showing a catheter 10 comprising an elongated cannula 12 of medical grade permissible plastic material, e.g. polypropylene, which has a connecting hub 14 made of the same or a comparable material, e.g. polypropylene is. The cannula 12 and the hub 14 are at the overlapping, to connecting ends 16 and 18 connected to one another. A needle 20 with a hub, as shown in FIG. 2, it can be inserted through the catheter 10. the The needle has a sharpened point 22 at its front end which is slightly above the conical end 24 of cannula 12 protrudes when the front of the hub of the needle in the rearward part of the hub 14 of the catheter 10 according to FIG.

The end 18 of the hub 14 is stepped (Figs. 3 and 4) so that a Shoulder 26 is formed with a radial wall 28 which axially away from the hub is directed.

The hub 14 is usually made of an appropriate medical grade permitted plastic material, such as polypropylene. An insert or ring part 30 made of an electrically conductive material with good ferromagnetic or induction heating properties has a size that it slides over the shoulder 26 and rests against the radial wall 28. The outer diameter of the ring 30 is smaller than the outer diameter of the intermediate shoulder 32 of the hub 14.

The cannula 12 is preferably an extruded part and can travel on the machine assembly and be manufactured by the method as described in the U.S. Patent 2,940,126 to Sheridan entitled ~ Making Conical medical-surgical tubes with controlled wall thickness by extrusion " is described. By the extrusion process according to US Pat. No. 2,940,126 it is possible, the base or end portion 16 of the cannula with an enlarged diameter to manufacture. The inner diameter of the end portion 16 is essentially that same as the outer diameter of the shoulder 26 so that it rests against the ring 30. The outside diameter of the end section 16 is approximately the same as the outside diameter the intermediate shoulder 32 and is therefore slightly larger than the outer diameter of the Ring 30.

The overlap connection of the end sections 16 and 16 to be connected 18 of the cannula 12 and the hub 14 and the interposed ring 30 are then in the field winding 34 of a corresponding induction heating generator is inserted and after power is applied to the generator, the ring 30 is heated and bonded the hub 14 and the plastic cannula 12 are permanently connected to one another.

There are a number of high frequency induction heating generators available for practicing the invention and these generators form no part the invention. A typical generator is a 1-K.W. model L-4-D the ~ Reeve Electronic Induction Unit. The generator includes a high voltage transformer and a rectifier which converts high voltage direct current to a self-exciting Vacuum tube oscillator gives up. A control circuit is designed so that it has a current regulation of the generator and protects the system from damage. A load winding, which surrounds the parts to be connected is cooled by a cooling water supply.

Under the influence of the induction heating system, hysteresis is used and eddy current losses generate heat in the metal ring 30. Eddy currents become generated by the effect of a transformer in a conductive metal part.

When a changing magnetic field on a conductive metal part is applied, there are eddy currents, which generate heat in cause the Xetallteil.

The induction heating generator generates a changing magnetic Field that generates the heat in the metal part.

Hysteresis heating occurs when the polarity of one is rapidly reversed Magnetic field, which acts on a metallic material.

By changing the intensity and speed of the magnetic field and the inversions, the amount of heating generated can be controlled.

A modified form of the invention is shown in Figs. 5 and 6, one part 40 having an undercut recess 42 and a protruding one Has sleeve 44. A metal ring 46 is over the sleeve 44 in the recess 42 inserted. There. second part 48 slides over sleeve 44 and rests against the ring 46 at. The nature of the materials of the first and second parts 40 and 48, respectively, are comparable and of a type which involves welding the parts together by deposition makes a corresponding amount of heat possible.

The parts to be connected or overlapped 40 and 48 are combined into one. Heating generator used, which is represented by the windings 34 and after the application of current, so much heat is generated in the ring 46 that the surrounding material of parts 40 and 48 melts. A minor one Pressure on parts 40 and 48 against one another when removed from generator 34 holds the parts when the material solidifies and creates a firm connection between the two.

Figure 7 shows another connection made using the invention is trained. A Y-shaped hub 50 is provided with Zwaiglinien 52, 54 and one Nozzle 56 is provided. The nozzle 56 has a sleeve 58 with a reduced diameter, over which a metal ring 60 is pushed. A cannula 62 from one with the The material comparable to the hub 50 has an enlarged end portion 64 which is pushed over the sleeve 58 and rests on the ring 60. The connection is made in an induction heating generator is used, whereupon the application of heat the cannula 62 is welded to the hub 50.

According to a modification of the invention, the ring is, for example, the ring 60 according to FIG. 7, with a differently colored plastic material 61 with a higher Melting point than the comparable materials of the parts to be connected 62 and 50 coated. The coating 61 can be made of Teflon or nylon, while the cannula 62 and hub 50 are made of polypropylene. Both Teflon as Nylon have higher melting points than the melting point of polypropylene, so that, when the superimposed parts 64 and 56 with the inserted ring 60 in the Induction heating generator are inserted, the heat generated in the ring so is controlled so that it is sufficient to cover the overlapping portions of the parts 64 and 56 to melt but not high enough to make the nylon or teflon of the ring to melt. The parts are taken out of the generator and can harden, whereupon the color of the notice 61 of the ring due to the overlying material the cannula 62 shines through. This allows instruments to be identified by color will.

The invention has particular application in any field in which the absence of contamination of the device and the total usability of the connection are critical, especially in the medical field, where any contamination that caused by the material used for the connection, or any inclination the connection to damage, can be fatal. The manufactured according to the invention Compound is completely operational and non-toxic. The nature of the connection pollutes the device or instruments are not, is extremely reliable and relative cheap.

Claims (8)

Claims XVerfatLren to do joining two separate parts of a medical Device made of similar plastic, characterized by the design of the to be connected Ends of the parts in such a way that they lie one inside the other, inserting a metallic arrangement between the nested ends, inserting the nested ends and applying the metallic arrangement in an induction heating device from induction heaters to the ends and the metallic arrangement, to this metallic To heat the arrangement and thereby soften the overlapping ends, remove of the parts from the heating device and cooling of the nested parts to create a medically acceptable 11 connection. 2. Ver £ a1irei # nacli claim 1, characterized in that during As the parts cool down, pressure is exerted on these plastic parts to press against each other. 3. The method according to claim 1, characterized in that the metallic Arrangement with a material of contrasting color and with a higher melting point Coated from similar plastic than the melting point of the two separate parts is and that the heating to below the melting point of the ßeschichtung, however is controlled above the melting point of the separate plastic parts, so that the parts are joined together without the coating of the metallic Arrangement melts. 4. Medical device with two separate parts from comparable Plastic and arrangements for connecting the imide parts to one another, marked by a metal ring (30, 46, 60) and an induction heating device (34), which causes in the ring a certain amount of heat is generated urid in the surrounding Plastic surfaces are released which are sufficient to melt the plastic, in such a way that the two plastic parts (12, 14; 40, 48; 5 (); 62) are welded to one another when induction heating is abKec3c # ic1itet 5. Device according to claim 4, characterized in that the plastic parts (12, 14; 40, 48; 50, 62) lie one inside the other and the metallic ring (30, 46, 60) is inserted between the two st. 6. Medical device with at least two separate plastic parts, each of which is made of one material identical to that of the other are comparable, characterized in that the end sections of the parts (12, 14; 40, 48; 50, 56) are superimposed with connecting sections, a metallic one Arrangement (30, 46, 60) is inserted between the nested parts and a connection between the two parts by mixing the material of the nested Parts is formed, mixing by generating heat through induction heating is effected in the metal assembly. 7. Medical device according to claim 6, characterized in that the metallic arrangement (60) has a contrasting color (61) on the outer surface has, which by the overlying sections of the plastic parts for identification shines through. 8. Medical device according to claim 6, characterized in that the metallic arrangement is a solid metal ring (30, 46, 60).