Method for producing a hollow needle

Abstract

Method for producing a hollow needle (1), wherein the hollow needle (1) comprises a hollow needle section (2) and a connecting section (3), wherein the hollow needle section (2) comprises a hollow needle functional region (7) and has a fastening region (6), wherein the fastening region (6) and the hollow needle functional region (7) are spaced apart in a longitudinal direction, wherein at least two radially opposite indentations (8) with accompanying plastic bulges (9) are introduced into the fastening region (6) by means of a forming tool, wherein the connecting section (3) is connected to the hollow needle section (2) in the fastening region (6) in a form-fitting and force-fitting manner, wherein the forming does not result in any significant narrowing or widening of the cross-sectional area and no significant reduction in the tube wall thickness, and the flow cross-section of the hollow needle remains approximately constant.

Description

Prior ArtThe invention relates to a metallic hollow needle (cannula) of a syringe or a connection piece, e.g. in the form of a Luer system, for use in medicine or as a pharmaceutical primary packaging.A syringe is a medical instrument which is used for administering medicaments, nutrient and infusion solutions, for removing body fluids or tissue, and for rinsing.A syringe, such as the needle syringe, the luer-cone syringe or the luer-lock syringe, consists of a cylindrical cavity, a plunger movable therein and a cone or cylindrical nozzle or with a screw thread on the nozzle. A hollow needle can be integrated into the syringe body, a hose or a connection piece in the form of a Luer system can be connected. The syringe bodies are predominantly made of a suitable material of plastic or glass.The focus in the design of the hollow needles is focused on the tube dimensions and in this case in particular on the ground-on design for the hollow needle tip. The design of the opposite end region of the hollow needle plays no significant role for the design. In order to improve the adhesion between the syringe body and the hollow needle, however, a partial region of the surface of the hollow needle can be modified by sandblasting or by introducing a general surface texturing by means of a laser beam.Hollow needles and production methods are known, for example, from the publications DE 10 2006 015 520 A1, EP 2 979 717 A1 and EP 3 471 799 B1. Further information on hollow needles and their production methods is given in the publications DE 17 24 115 U, U.S. Pat. No. 3,186,408 A and U.S. Pat. No. 3,470,604 A.The laid-open specification DE 10 2016 121 414 A1, for example, describes a method for processing a hollow needle, comprising the steps of: providing a hollow needle; modifying a region of a surface of the hollow needle by at least one laser beam; and connecting the hollow needle to at least one further component in the modified region; wherein the at least one laser beam is a pulsed laser beam having a pulse duration below 30 ps.When manufacturing syringes from plastic, the hollow needle can be directly injection molded or manufactured with a Luer system with an integrated hollow needle. By direct injection molding of the hollow needle, the sticking of the hollow needle can be omitted.Syringes made of glass can be produced with a Luer system with an integrated hollow needle or by direct adhesion of the hollow needle into the syringe body, for example with a UV-curing adhesive.Object and Disclosure of the InventionAccording to the invention, a method for producing a hollow needle having the features of claim 1 is proposed. Furthermore, a hollow needle, in particular obtained with the method, is proposed. Preferred or advantageous embodiments of the invention are evident from the dependent claims, the following description and / or the appended figures.Important criteria for the integration of the hollow needle into the syringe body or into a Luer system are the hermetic sealing effect and the pull-out resistance. When overmolding the hollow needle or when gluing the hollow needle, the bond between the two materials is based on a force-fit or material-to-material bond or a combination of the two types of connections. Particularly challenging aspects result from the fact that the properties of the produced compounds can be adjusted in a targeted manner by the selection of the material combinations, the geometry and in particular the injection molding parameters and by supplementary method steps.A positive-locking connection is formed by the meshing of at least two connection partners by means of a suitable configuration of the boundary surface geometry. In the context of the functionality, a distinction is made between a macroscopic, such as e.g. geometric notch, and microscopic, such as e.g. surface roughness, form of the form fit. This is achieved by injection molding through apertures or undercuts in the insert part or in a previously injected component during the injection molding of the subsequent component. The positive bond strength depends on the type of load, on the materials used, the dimensions and the cross-sectional geometry of the positive-locking element. Thus, both a fixed connection can be realized and a movable composite can be realized in the case of specific non-adhesion.Frictional engagement is produced by the application of force, which is generated by suitable tension. These include, for example, pressure or friction forces which transmit forces or torques determined by suitable clearance or press fits. For this purpose, the different shrinkage of the individual materials is used in a targeted manner during the production of the composites. By means of a suitable material pairing and an adapted manufacturing process, the criteria, such as material incompatibility, process compatibility and tribological properties, such as friction and wear, can be influenced.In order to realize a cohesive connection between two components, compatibility of the two joining partners must be ensured. Originally incompatible materials can be joined by chemical modification (e.g. copolymerization) or by physical surface treatment (e.g. plasma) in a materially integral manner. Important process parameters in an injection molding process, such as, for example, temperature of the compound, holding pressure or injection speed, significantly influence the adhesion. During bonding, the quality is predominantly determined by the needle positioning, the adhesive dosage, the curing of the adhesive, the material used and the design.By a mutual radial stress of a metallic hollow needle (cannula) with a forming tool, a targeted low plastic indentation (forming) with an accompanying lateral plastic bulge is produced. The resulting and permanent deformation serves as a macroscopic form-fitting connection during the assembly of the hollow needle with the syringe body by injection molding with plastic or by molding in glass or by adhesive bonding into a syringe body made of plastic or glass. As a result, the pull-out resistance of the hollow needle is significantly increased and the axial and rotational movement of the hollow needle in the syringe body is prevented. For the reinforcing effect of the positive fit, this forming can be applied not only once but several times with the option of an angular offset in the circumferential direction. In the case of glass syringes, there is also the great advantage that the complicated hollow needle adhesion with a possibly harmful adhesive is dispensed with and the hollow needle can be formed directly into the syringe cone within the scope of the classic production process. This possibility for creating the positive connection can also be used with metallic lancets.The present invention is characterized in that the low plastic and permanent radial deformation with accompanying lateral plastic bulges serves as a macroscopic positive connection between the hollow needle and the syringe body or a connecting piece, e.g. in the form of a Luer system. As a result, the pull-out resistance of the hollow needle is significantly increased and the axial and rotational movement of the cannula in the syringe body is prevented. For the reinforcing effect of the positive fit, this forming can be applied not only once but several times with the option of an angular offset in the circumferential direction.In hollow needles, no substantial narrowing or widening of the cross-sectional area occurs after the forming, no substantial reduction in the tube wall thickness occurs and the flow cross-section of the hollow needle remains approximately constant.In the case of glass syringes, there is also the great advantage that the complicated hollow needle adhesion with potentially harmful adhesive is dispensed with and the hollow needle can be formed directly into the syringe cone within the scope of the classic production process with an adapted process control as a result of the different shrinkage behavior of the individual materials. This possibility for creating a positive fit in the form of a radial plastic deformation with an accompanying lateral plastic bulge can also be applied to metallic lancets.From the present disclosure, further application examples are obvious to the expert in which a hollow needle or hollow tube or solid needle or solid body processed according to the invention can be advantageously used.Further features, advantages and effects of the invention will become apparent from the following description of preferred exemplary embodiments of the invention. The following are shown: FIG. 1 shows a schematic sectional view of the front syringe body with hollow needle, FIGS. 2a, b show a schematic of the hollow needle.Corresponding or identical parts are each provided with the same reference numerals in the figures.FIG. 1 shows a schematic sectional view of a front syringe body. The front part of the syringe body is formed with a hollow needle 1. The syringe body comprises a hollow needle section 2 and a connection section 3. the connection section 3 is formed from a plastic or glass and has a rear section 4 for coupling to the syringe body and a front section 5, wherein the hollow needle section 2 is connected in the front section 5 in a positive fit and force fit manner to the connection section 3.The hollow needle 1 is formed of a metal or an alloy. The hollow needle 1 has a fastening region 6 and a hollow needle functional region 7. The hollow needle functional region 7 is, for example, beveled, pointed and / or sharp-edged. The fastening region 6 has radially opposite indentations 8.The indentations 8 are introduced by means of a forming tool, wherein the indentations 8 are accompanied by bulges 9 (FIG. 2 ). The hollow needle 1 is connected in a form-fitting and force-fitting manner to the connection section in the fastening region 6, for example by injection molding with plastic or by molding in glass, wherein the indentations 8 and bulges 9 bring about particularly good retention and / or connection of hollow needle section 2 and connection section.FIG. 2 ashows schematically the hollow needle section 2 with the hollow needle functional region 7 and the fastening region 6. the indentations 8 and the bulges 9 resulting during the forming are arranged in the fastening region 6. The embodiment provides a plurality of mutually opposite depressions 8 which are spaced apart in the longitudinal direction of the hollow needle portion 2. Preferably, the indentations 8 spaced apart in the longitudinal direction are rotated and / or displaced in the circumferential direction.FIG. 2 bshows a cross section through the hollow needle section 2 from FIG. two, wherein the plurality of indentations 8 and bulges 9 and the arrangement offset in the circumferential direction can be seen.List of reference characters1 Hollow needle 2 Hollow needle section 3 Connecting section 4 Rear section 5 Front section 6 Fastening region 7 Hollow needle functional region 8 Depression 9 Bulge

Claims

Method for producing a hollow needle (1), wherein the hollow needle (1) comprises a hollow needle section (2) and a connection section (3), wherein the hollow needle section (2) comprises a hollow needle functional region (7) and has a fastening region (6), wherein the fastening region (6) and the hollow needle functional region (7) are spaced apart in a longitudinal direction, wherein at least two radially opposite indentations (8) with accompanying plastic bulges (9) are introduced in the fastening region (6) by means of a forming tool, wherein the connection section (3) is connected to the hollow needle section (2) in the fastening region (6) in a positive-locking and non-positive-locking manner, wherein no substantial narrowing or widening of the cross-sectional area and no substantial reduction in tube wall thickness occurs as a result of the forming and the flow cross section of the hollow needle remains approximately constant.Method according to claim 1, characterised in that a plurality of indentations (8) and plastic bulges (9) lying opposite one another in pairs are introduced.Method according to claim 1 or 2, characterised in that the connection section (3) is connected to the hollow needle section (2) in a form-fitting and force-fitting manner by injection moulding with plastic.Method according to claim 1 or 2, characterised in that the connection section (3) is connected to the hollow needle section (2) in a form-fitting and force-fitting manner by being formed into glass.Hollow needle (1) with a hollow needle section (2) and a connection section (3), wherein the hollow needle section (2) has a fastening region (6) and a hollow needle functional region (7), wherein the fastening region has radially opposite depressions (8) and plastic bulges (9) in pairs, wherein the hollow needle section (2) is connected to the connection section (3) in the fastening region (6) in a form-fitting and force-fitting manner, wherein no substantial narrowing or widening of the cross-sectional area and no substantial reduction in tube wall thickness occur as a result of the forming and the flow cross section of the hollow needle remains approximately constant.

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