Braun Aktiengesellschaft

Friedrich Blume

Lutz Voigtmann

A method for producing a shear element having protrusions on the skin contacting surface thereof, including the steps of coating an electrically conductive surface with a photoresist, exposing the photoresist to a hold pattern and developing the photoresist to produce a grid pattern wherein the electrically conducting surface is exposed, the grid pattern defining hole areas wherein the electrically conductive surface is covered by islands of photoresist of a predetermined thickness, introducing irregularities into the surface elevation of the exposed grid, the surface irregularities being of lesser dimension of the thickness of the photoresist islands, depositing an intermediate foil onto the exposed grid overlying the introduced surface irregularities, the intermediate foil being of sufficient thickness to extend above the photoresist islands when deposited, depositing a shear foil overlying the intermediate foil, and removing the shear foil from the intermediate foil, thus producing a shear foil having protrusions on the skin contacting surface thereof but having relatively smooth surface in the regions surrounding shear openings corresponding to the locations of the photoresist islands.

Shear foil having protrusions on its skin-contacting surface thereof

A shear foil and method of making the same includes providing a surface of a matrix element with a grid of depressions, and overfilling the depressions with a metallic molding substance so as to form a plurality of metallic inserts each of which overlaps a narrow annular region of the surface which bounds a respective depression filled by the respective insert. A layer of metallic screen-forming substance is thereupon deposited over the metallic inserts so as to form a screen having a plurality of openings which extend to the surface intermediate respectively adjacent inserts. The screen also has a face comprised of annular face portions each of which surrounds one of the inserts and which is juxtaposed with the surface of the matrix element. The deposition of a layer of sealing material over the surface of said screen which faces away from said surface of said matrix element, follows. The matrix element is thereupon separated from the screen and the inserts so as to expose the latter and said face. A layer of wear-resistant substance, such as chromium, is then deposited over the exposed face and inserts. The portion of the wear-resistant layer which is deposited on the inserts and thereupon removed from the screen while the remaining portion of the wear-resistant layer on the annular face portions by separating the inserts from the screen. An additional layer of hydrogen-impermeable substance may also be deposited intermediate the matrix element and the screen.

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Schwalbach, Germany

Friedrich Blume