Method for chemical etching of a needle cannula

Patent metadata

Field	Value
Publication number	US-9822455-B2
Application number	US-201013497472-A
Country	US
Kind code	B2
Filing date	Sep 20, 2010
Priority date	Sep 21, 2009
Publication date	Nov 21, 2017
Grant date	Nov 21, 2017

Abstract

A regular metallic, cylindrical tubular needle cannula ( 1 ) is subjected to a metal etching liquid ( 21 ) in the inside lumen ( 4 ) thereby increasing the inside diameter and enhancing the flow properties while maintaining the outside appearance. The inside diameter is only increased over a controlled length ( 7 ) of the full length of the needle cannula ( 1 ) leaving sufficient length and wall thickness to also taper the outside diameter.

First claim

The invention claimed is:

1. A method of manufacturing needle cannulas comprising:
providing a plurality of metallic needle cannulas ( 1 ) having a back end ( 2 ) and a front end ( 3 ) and an oblong inside lumen ( 4 ) there between,
providing a protection on at least a part of the outside surface ( 8 ) of at least one of the plurality of needle cannulas ( 1 ),
providing a pressurized metal etching liquid ( 21 ),
the needle cannula comprises a part ( 7 ) having a length less than the full axial length of the needle, and a remaining part having a length corresponding to the full axial length minus the length of the part ( 7 ),
transferring the pressurized metal etching liquid ( 21 ) into a part ( 7 ) of the oblong inside lumen ( 4 ) of the metallic needle cannula ( 1 ), wherein the protected part of the outside surface ( 8 ) is commensurate with the part ( 7 ), thereby the etching increases a diameter of the part ( 7 ) of the inside lumen ( 4 ) without decreasing the outer diameter of the needle cannulas ( 1 ) in the areas where the protection of the outside surface of the at least one of the plurality of needle cannulas is provided, and thereby obtaining at least one needle cannula having a reduced wall thickness at the back end ( 2 ) at a length corresponding to the axial part ( 7 ), and an unchanged wall thickness at the front end ( 3 ) corresponding to the remaining part.

2. A method of manufacturing needle cannulas according to claim 1 further comprising:
exposing the metal etching liquid ( 21 ) to a centrifugal force, thereby building up pressure in the metal etching liquid ( 21 ).

3. A method of manufacturing needle cannulas according to claim 1 , where the diameter of the part ( 7 ) of the inside lumen ( 4 ) is increased by controlling how far the metal etching liquid ( 21 ) travels inside the lumen ( 4 ) of the needle cannula ( 1 ).

4. A method of manufacturing needle cannulas according to claim 1 , wherein the protection on at least a part of the outside surface of at least one of the plurality of needle cannulas comprises a coating, or a sacrificial anode placed in contact with the etching liquid.

5. A method of manufacturing needle cannulas according to claim 1 further comprising:
pumping the metal etching liquid ( 21 ) into the part ( 7 ) of the inside lumen ( 4 ) of the metallic needle cannulas ( 1 ) thereby building up pressure in the metal etching liquid ( 21 ).

6. A method of manufacturing needle cannulas according to claim 5 further comprising:
cathodic protecting the individual needle cannulas ( 1 ) by providing a sacrificial anode ( 31 ) in contact with the metal etching liquid ( 21 ) and in electrical contact with each individual needle cannula ( 1 ).

7. A tool ( 40 ) for supporting the plurality of needle cannulas ( 1 ) when subjected to the method of claim 2 , the tool ( 40 ) comprising a plurality of flexible parts ( 44 ) which each seals an area of the outside surface of each needle cannula ( 1 ) from being in contact with the metal etching liquid ( 21 ) during the execution of the method.

8. A method of manufacturing needle cannulas according to claim 7 further comprising:
moving the metallic needle cannulas ( 1 ) and the metal etching liquid ( 21 ) relatively to each other such that the etching liquid flows into a part ( 7 ) of the inside lumen ( 4 ).

9. A method of manufacturing needle cannulas according to claim 8 wherein the metallic needle cannulas ( 1 ) are moved relatively to metal etching liquid ( 21 ).

10. A method of manufacturing needle cannulas according to claim 8 wherein the metal etching liquid ( 21 ) is moved relatively to the metallic needle cannulas ( 1 ).

Assignees

• Larsen Andre
• Christoffersen Lasse Wengel
• Andersen Mikael
• Preuthun Jan Harald
• Novo Nordisk As

Inventors

• Larsen Andre
• Christoffersen Lasse Wengel
• Andersen Mikael
• Preuthun Jan Harald

Classifications

• C23F1/04 Primary

  Chemical milling · CPC title

• A61M5/32

  Needles; Details of needles pertaining to their connection with syringe or hub (infusion needles A61M5/158); Accessories for bringing the needle into, or holding the needle on, the body {(A61M5/42, A61M5/46 take precedence; guide needles for catheters A61M25/065)}; Devices for protection of needles {(apparatus specially adapted for cleaning or sterilising needles A61M5/001)} · CPC title

• A61B2017/00526

  Methods of manufacturing · CPC title

• A61M2207/00

  Methods of manufacture, assembly or production · CPC title

• B21G1/006

  Special treatments of pins or needles, e.g. annealing, straightening · CPC title