Adhesive bonding and miscellaneous chemical manufacture – Delaminating processes adapted for specified product – Delaminating in preparation for post processing recycling step
Patent
1992-07-06
1994-03-29
Powell, William
Adhesive bonding and miscellaneous chemical manufacture
Delaminating processes adapted for specified product
Delaminating in preparation for post processing recycling step
156643, 156644, 1566591, 156668, 156345, 20412965, B44C 122, B29C 3700, C23F 100
Patent
active
052981150
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to the production of prostheses such as are used in orthopaedic and trauma surgery for pinning broken bones.
BACKGROUND ART
Conventionally, such prostheses are selected by the surgeon from a set or kit of standard sizes and shapes of plates or strips having pre-drilled holes for screws. These may be capable of some limited bending and/or cropping to adapt a specific size of strip or shape to more closely suit the circumferences of any particular fracture. Generally speaking, however, the type of pinning possible using these conventional prostheses is limited in scope because of their 2-dimensional configuration which is often unsatisfactory from both a surgical and mechanical strength point of view.
The difficulties involved in bending have led to proposals for mechanical aids to bending so-called osteosynthetic plates during surgery, such proposals being contained in DE-OS-37 24 479 and DE-OS-29 20 223. However, these aids do not facilitate anything like the full range of prosthetic shapes necessary and even so require still a considerable inventory of shapes and sizes of osteosynthetic plates.
A wider range of prosthetic shapes would facilitate different and better pinning techniques, but the prefabrication of a complete range would be a near-impossible task and the maintenance of a comprehensive inventory to cover all eventualities prohibitively expensive, to say nothing of the difficulty of selecting a shape and size from such a plethora of possibilities.
The custom-production of prostheses precisely adapted to a particular fracture has to date been substantially ruled out because of the time required to produce such prostheses by conventional production techniques and the lack, in any event, of workshop facilities close to the operating theater.
SUMMARY OF THE INVENTION
The present invention provides methods and apparatus for the production of articles that inter alia facilitate the rapid, on-site production of medically supervised custom-made prostheses.
The invention comprises a method for the rapid, one-off or small batch production of a shaped article such as a surgical prosthesis characterized by comprising the steps of of the predetermined shape or a processed blank from which an article of the predetermined shape may be made by bending the blank, and electrochemical machining) process in which resist is removed by a computer aided design/manufacturing method.
Usually, the material will be 18/8 type stainless steel, but the development of other medically suitable materials such as titanium or plastics cannot be ruled out.
The blank may be prepared with fold lines which may be made by etching or, more rapidly, by electrochemical machining (ECM). Features other than fold lines may also be etched such for example as apertures as for screws and pins and the required perimeter of the prosthesis.
Although removing the resist layer could be done by the usual photographic methods, these are seen as unacceptably slow, as currently practiced. So the acid resist layer, which may comprise a wax, collodial gel or plastic or rubber adhesive film coating, may be removed mechanically as by a blade, a rotary tool or an ultrasonic tool, or by vaporization as by an electric discharge or laser. The resist layer may also be removed by selectively applying a chemical reagent or solvent as by an airbrush or jet printer. The resist may also, of course, be selectively applied, rather than applied overall and then removed selectively.
The blank may be etched concurrently on both faces, especially for the production of screw and/or pin apertures and the perimeter, but also for producing oppositely-directed curved regions. Etching of such features can leave sharp ridges or burrs, which can be removed by electropolishing. Screw and/or pin apertures or holes may also be produced by a drill or punch or other purely mechanical means where convenient.
The blank may be processed using numerically-controlled tool means, such as a blade or rotary tool, laser or an airbrush or jet print
REFERENCES:
patent: 3325319 (1967-06-01), Frantzen
patent: 3420142 (1969-01-01), Gale
patent: 3508108 (1970-04-01), Salisbury
patent: 4466858 (1984-08-01), Poler
Production Engineer, Jun. 1987, pp. 14-16, "High Production Chemical Milling".
Patent Abstracts of Japan, vol. 13, No. 121 (E-732)(3469), JP-A-63-289990, Nov. 28, 1988, Tasuku Fujii, et al., "Manufacture of Printed Wiring Board".
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