Patent DE-10062106-A1 (DE)
Title: Aerostatic thrust bearing, for the free end of an open-end spinning rotor shaft with an air gap, has a choke in the air feed to the gap formed by structured micro-pore holes
Inventor: BOCK ERICH
IPC: F16C32/06
Filed: 2000-12-13
Abstract: The thrust bearing (1) for the free end of a rotor shaft, at an open-end spinner, is an aerostatic bearing with an air gap. The air is fed into the gap through a choke (2), with a number of micro-pore holes (4) to set the volume of air fed into the gap.  The air choke, for the air gap at an aerostatic thrust bearing for the free end of an open-end spinning rotor shaft, has micro-pore holes distributed over a surface, in a matrix layout, or in spirals or stream paths away from each other, in path/stream curves against the direction of shaft rotation. The micro-pore holes can also be arranged in concentric circles. The micro-pore holes have a cross section which increases towards the outlet side, forming a cone at the outlet side, and also expand towards the inlet side forming an inlet cone. The inlet side of the micro-pore holes is connected to an air reservoir, held within the pores of a porous material. The micro-pore holes are drilled by laser beams, electron or ion beams, or they are etched e.g. anisotropic etching in a crystalline material. The micro-pore holes can be formed in a thin film or disk. Recesses can be formed at the inlet and/or outlet sides of the choke, with a larger cross section than the micro-pore holes, linked to them at the outer side(s). A number of micro-pore holes can be linked to one recess, and have a larger diameter at their outlet sides. The choke and the bearing are of the same materials, while the bearing and the end of the rotor shaft are of low-friction paired materials. The bearing surface (7) of the bearing is a plastics with a high heat resistance. In the paired materials, the first is graphite or carbon, or a metal. The second material of the pair is a hard material e.g. ceramic and preferably silicon carbide or boron nitride. One and/or both of the materials in the pair can have a low-friction additive. The bearing has a recess (8) to monitor wear, as a blind drilling. The facing surfaces of the bearing and the rotor shaft have a trough shape, and preferably in a cone or a dome. A particle filter is in front of the choke, of a porous material in one piece with the choke.  An Independent claim is included for the production of a rotor shaft bearing, at the open-end spinner, where the choke is in one piece in front of the bearing surface and forms part of the bearing surface. Preferred Features: A pulsed laser beam is used to drill the micro-pore holes, with a short laser beam wavelength  <= 300 nm. During drilling, the gap is shortened or kept constant between the laser optical system and the choke. A single laser beam is divided by a lens system into a number of part-beams, to drill a number of micro-pore holes simultaneously. The micro-pore holes can also be etched using a mask produced by photolithography. The etching can also be using wet chemicals or in a dry process, and especially plasma etching. Or the micro-pore holes can be in a crystalline material with anisotropic etching. The holes can also be drilled by electron or ion beams. The micro-pore hole structure can be in a thin film or disk fitted to the choke before or after drilling.