Abstract: According to a prior art method for producing a cylindrical component comprised of silica glass, a cylinder comprised of a softened silica glass mass is drawn in a predetermined drawing direction along a drawing axis by means of a drawing device which acts upon said cylinder. The aim of the invention is to provide a method which prevents, to the greatest possible extent, warping of the drawn cylinder and other deviations from the ideal cylinder dimensions and to prevent, to the greatest possible extent, the outer surface of the drawn cylinder from being touched. To these ends, the invention provides that the drawing device comprises a plurality of guide elements which are arranged one behind the other along the drawing axis, and which can be displaced independently of one another in a drawing direction and in a direction opposite thereto.

Abstract: The invention concerns a device (1) for sintering of a porous mold body (2) in a gas-tight chamber (3), with the mold body (2) hanging loose from a link chain (7) so that it can be fed continuously to a heating zone (5). In the area of the upper boiler (10), the traction direction of the link chain (7) is reversed by a deviation wheel (11). The tensile force is transmitted via a traction rope (13) that can be taken up on a take-up reel (14), such take-up reel (14) being driven by a drive (16) arranged outside the chamber (3). A drive shaft (15) for the take-up reel (14) provides for easy sealing of the duct (18) towards the chamber (3), because only a rotation and not a simultaneous axial displacement is required for the hoisting movement, and moreover, because the duct (18) is arranged at a spatial distance from the heating zone (5).

Abstract: The invention concerns a device (1) for sintering of a porous mold body (2) in a gas-tight chamber (3), with the mold body (2) hanging loose from a link chain (7) so that it can be fed continuously to a heating zone (5). In the area of the upper boiler (10), the traction direction of the link chain (7) is reversed by a deviation wheel (11). The tensile force is transmitted via a traction rope (13) that can be taken up on a take-up reel (14), such take-up reel (14) being driven by a drive (16) arranged outside the chamber (3). A drive shaft (15) for the take-up reel (14) provides for easy sealing of the duct (18) towards the chamber (3), because only a rotation and not a simultaneous axial displacement is required for the hoisting movement, and moreover, because the duct (18) is arranged at a spatial distance from the heating zone (5).

Abstract: In a known procedure for manufacture of a quartz glass body, a glass starting material and fuel gas are fed to a rotationally symmetrical deposition burner (1) having several annular gap nozzles (7-9) and being formed by coaxial arrangement of a number of quartz glass tubes (2-5), such glass starting material in a burner flame forming SiO2 particles which, under back and forth motion of the deposition burner (1) along the longitudinal axis of a rotating mandrel (12), are deposited on such rotating mandrel under formation of an essentially cylindrical porous blank. To enable replacement of such deposition burner without major efforts in terms of work and costs, the procedure of the inventioin proposes to use a deposition burner (1) the annular gap nozzles (7- 9) of which have gap widths with a maximum dimensional deviation of 0.

Abstract: In a known procedure for manufacture of a quartz glass body, a glass starting material and fuel gas are fed to a rotationally symmetrical deposition burner (1) having several annular gap nozzles (7-9) and being formed by coaxial arrangement of a number of quartz glass tubes (2-5), such glass starting material in a burner flame forming SiO2 particles which, under back and forth motion of the deposition burner (1) along the longitudinal axis of a rotating mandrel (12), are deposited on such rotating mandrel under formation of an essentially cylindrical porous blank. To enable replacement of such deposition burner without major efforts in terms of work and costs, the procedure of the invention proposes to use a deposition burner (1) the annular gap nozzles (7-9) of which have gap widths with a maximum dimensional deviation of 0.

Abstract: The invention concerns a drilling device (1) for brittle materials with a drill head (2) detachably fixed to a drilling rod (3) by means of a positive-lock connection for transmission of the drilling torque. For its exact relative positioning, the drill head (2) has a conical shape (10) which in the represented operating state engages centrally into a corresponding recess (11) of the drilling rod (3). As a protection against any axial loosening, a fixing device or arrest (15; 20) designed as a hollow nut is provided engaging into a thread (16) of the drill head (2) and into a thread (17) of the drilling rod (3), the threads (16, 17) having countercurrent pitches. By rotating the arrest (15), the drill head (2) and the drilling rod (3) can thus be simply braced against each other or pulled away from each other, the connection enclosed by the arrest (15) having optimum protection from external influences at the same time.

Abstract: A hollow cylinder is held in a vertical orientation and sent continuously through a heating zone for sintering. In a first phase of the sintering operation, the hollow cylinder stands on a support while the upper end (12) of the cylinder is being sintered. In a second phase the cylinder hangs from a hanging element while its lower end (10) is sintered. A vertical rod is fixed to the base on which the lower end is supported, and extends through the hollow cylinder. A retaining ring is fixed inside the upper end of the hollow cylinder. During the first phase, the upper end vitrifies and contracts so that the retaining ring engages the vertical rod. Longitudinal contraction causes the lower end to lift off the base so that the cylinder is suspended during the second phase.

Abstract: A layer of quartz glass soot is deposited continuously on a substrate consisting of quartz glass grains with a lower degree of sintering activity than the quartz glass soot and the soot is sintered by passing it continuously through a heating zone to form a quartz glass strip which is severed to form plates. Apparatus for implementing the process includes a conveyor suitable for the transport of quartz glass grains; a loading device for the deposition of the quartz glass grains onto the conveyor; nozzles for depositing a layer of synthetic quartz glass soot on the quartz glass grains; and a heating unit to heat the layer.

Abstract: The mold wall forms the boundary of a cavity provided with a filling opening and is divided vertically into several segments, which are connected to each other in such a way that they can separate under the action of a force acting outward from the cavity. At least one pretensioned elastic element is installed outside the cavity, which is in effective contact with at least one segment, so that, because of the pretension, an elastic force acts on the segment in the direction toward the cavity. A tensioning element is provided to pretension the elastic element, this tensioning element being installed outside the mold wall to serve as an abutment for the elastic element, and that the elastic element be made of a creep-resistant material.

Abstract: A hollow cylinder is held in a vertical orientation and sent continuously through a heating zone for sintering. In a first phase of the sintering operation, the hollow cylinder stands on a support while the upper end (12) of the cylinder is being sintered. In a second phase the cylinder hangs from a hanging element while its lower end (10) is sintered. A vertical rod is fixed to the base on which the lower end is supported, and extends through the hollow cylinder. A retaining ring is fixed inside the upper end of the hollow cylinder. During the first phase, the upper end vitrifies and contracts so that the retaining ring engages the vertical rod. Longitudinal contraction causes the lower end to lift off the base so that the cylinder is suspended during the second phase.

Abstract: A drill head carries a plurality of coaxially mounted drill crowns beginning with a first crown and followed by additional drill crowns which, upon rotation, describe concentric envelope circles of successively larger diameters. The first drill crown has cutting elements with a diamond coating with an average particle size of 200-1,000 .mu.m, and the additional drill crowns have cutting elements with a diamond coating with an average particle size of 200-300 .mu.m. The difference in diameter of succeeding drill crowns is successively small. Alignment of the drill crowns in a pilot hole is achieved by guide elements mounted behind the drill crowns and describing an inner envelope circle which is smaller than the outer envelope circle described by the largest drill crown, thereby defining a radial safety gap into which fluid is fed to form a cushion during rotation.

Abstract: A vertical drying chamber, for the continuous drying of finely divided solids at temperatures in the range of 800.degree. to 1000.degree. C. by the evaporation of moisture adhering thereto, is formed by the interstice between an inner tube and an outer tube. The outer tube is surrounded by a heat source (electrical resistance heating, infrared radiator) and is composed of a plurality of tube sections plugged one into the other, each tube having a funnel-shaped upper end into which the bottom, plain end of the tube section above it extends. Between the interconnected tube ends spacers are provided. The tube sections are made of a material that is permeable to infrared radiation.

Abstract: Disclosed is a method for the axial building up, in a vertical arrangement, of a hollow cylindrical soot body having no internal support and consisting substantially of silicon dioxide by means of at least one flame hydrolysis build-up burner serving for the soot production. In this method the soot is deposited at the beginning of the build-up onto an auxiliary body, and during the build-up the build-up burner and the growing soot body are rotated relative to one another, and the burner is at the same time held at an unvarying distance from the growing end of the hollow cylinder and centrally above the predetermined cross section of the upwardly growing end of the cylinder wall. The penetration of soot into the interior of the cylinder is prevented by means of a directed gas stream.

Abstract: The lightweight mirror has a special core construction. The core consists of flat and/or tubular pieces which are joined together by means of a sintering composition. The sintering composition has open pores. In the production of the core, the sintering composition is poured into interstices between pairs of adjacent flat and/or tubular pieces and heated to the sintering temperature in a nonoxidizing atmosphere together with the flat and/or tubular pieces. A layer of sintering composition can be provided on the faces of the front and/or back plate of the lightweight mirror which confront the core. Stiffening rods can be embedded in the sintering composition.

Abstract: A light-weight mirror for astronomical purposes is disclosed. The mirror consists of a mirror plate, a back plate and a supporting framework disposed between them and consisting of a plurality of rows of tubes. The rows of tubes are staggered one from the other. Each tube in a row has a line or strip of contact with two adjacently disposed tubes of the next row. The tubes are welded together along the contact line or strip. The thickness of the tube wall is reduced in the area of the contact line or strip.

Abstract: A light-weight mirror comprising a fused-silica mirror plate and a cellular or honeycombed supporting structure made of fused silica or a quartzose material. As it is being welded or fused to the supporting structure, the mirror plate is supported by supporting elements comprising seating members which at elevated temperature do not react with fusted silica. The surface of the seating members facing the mirror plate may be plane or curved or domed. The seating members are made of graphite or zirconium oxide. The supporting elements may also be made entirely of graphite. After the supporting structure and the mirror plate have been welded together, the supporting elements are removed.