Method for producing abrasive particles
AssigneeTyrolit Schleifmittelwerke Swarovski K.G.
InventorMartin HIRSCHMANN
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Abstract
A method for producing abrasive particles includes: i) providing a starting mixture which contains at least aluminum hydroxide and which can be converted at least into aluminum oxide by a heat treatment, ii) extruding the starting mixture in order to form an extrudate, iii) separating the extrudate into intermediate particles, and iv) heat-treating the intermediate particles. The intermediate particles are converted into abrasive particles which contain aluminum oxide, and the starting mixture is pressed through at least one nozzle element with a plurality of substantially parallel nozzle channels. The nozzle channels are preferably arranged in a mutually spaced manner over the course of the extrusion process, and the extrudate has a spiral or hollow cylindrical shape at least in some sections.
Claims15
A method of producing abrasive particles having the following method steps:
- i. providing a starting mixture which contains at least aluminum hydroxide and which can be converted at least into aluminum oxide by heat treatment,
- ii. extrusion of the starting mixture to form an extrudate,
- iii. separating the extrudate into intermediate particles, and
- iv. heat treatment of the intermediate particles, wherein the intermediate particles are converted into abrasive particles which contain aluminum oxide,
- wherein in the course of extrusion the starting mixture is pressed through at least one nozzle body having a plurality of nozzle passages which extend substantially parallel and which are preferably mutually spaced, wherein the extrudate is at least portion-wise of a spiral or hollow-cylindrical configuration,
- wherein the nozzle passages of the at least one nozzle body respectively have a preferably circular or ellipsoidal inlet opening through which the starting mixture passes into the nozzle passages and a respective outlet opening which is preferably rectangular, square, triangular or star-shaped and/or has at least one convex side or at least one concave side and by way of which the extrudate issues from the nozzle passages,
- wherein a part of the nozzle passages, preferably all nozzle passages, have a portion which adjoins the outlet opening and which is in the form of a twisted prism whereby the starting mixture is converted into a spiral shape, and/or
- that a part of the nozzle passages, preferably all nozzle passages, have a portion which adjoins the outlet opening and in which at least one interference body is arranged whereby the starting mixture to be extruded is converted into a hollow geometry, preferably wherein the at least one interference body is connected to an inside wall of the nozzle passages by way of at least one bar, preferably precisely three bars, and/or wherein the at least one interference body is arranged substantially centrally in the nozzle passages and/or wherein the at least one interference body has a torpedo-shaped tip facing towards the inlet opening, and/or
- that the extrudate leaving the at least one nozzle body is deflected by at least one baffle body, preferably on to a spiral path, preferably wherein the at least one baffle body is arranged directly adjacent to the at least one nozzle body and/or has at least one baffle surface arranged inclinedly relative to the at least one nozzle body and/or has at least one shovel-shaped baffle surface.
The abrasive particles as set forth in claim 12, wherein the abrasive particles are of a length of 0.5 mm to 4 mm, preferably between 1 mm and 2 mm, and/or
- that the abrasive particles are of a width of 200 μm to 800 μm, preferably between 500 μm and 700 μm, and/or
- that the abrasive particles are of a thickness of 50 μm to 400 μm, preferably 150 μm to 250 μm and/or
- that the abrasive particles have a twist angle between 0° and 360°, preferably between 180° and 360°.
Dependencies are inferred from the claim text.