Methods or machines specially adapted for the production of tubular articles

BPERFORMING OPERATIONS TRANSPORTING B28Stoneworking B28BSHAPING CLAY OR OTHER CERAMIC COMPOSITIONS, SLAG, OR MIXTURES CONTAINING CEMENTITIOUS MATERIAL

B28B21/00Methods or machines specially adapted for the production of tubular articles

B28B21/02by casting into moulds B28B21/04by simple casting, the material being neither positively compacted nor forcibly fed B28B21/06into moulds having sliding parts B28B21/08by slip-casting Moulds therefor B28B21/10using compacting means B28B21/12tamping or ramming the material or the mould elements B28B21/14vibrating B28B21/16one or more mould elements B28B21/18using expansible or retractable mould or core elements B28B21/20using inflatable cores B28B21/205having a rigid frame inside the inflatable part of the core B28B21/22using rotatable mould or core parts B28B21/24using compacting heads, rollers, or the like B28B21/242the working diameter of the compacting mechanism being adjustable B28B21/245using a horizontal compacting roller in a horizontally rotatable mould B28B21/247the rollers of the compaction head being driven B28B21/26with a packer head serving as a sliding mould or provided with guiding means for feeding the material B28B21/28combined with vibration means B28B21/30Centrifugal moulding B28B21/305Moulding machines with vertical rotation axis B28B21/32Feeding the material into the moulds B28B21/34combined with vibrating or other additional compacting means B28B21/36applying fluid pressure or vacuum to the material B28B21/38introducing the material wholly or partly under pressure; Injection-moulding machines B28B21/40by evacuating one or more of the mould parts; Vacuum machines B28B21/42by shaping on or against mandrels or like moulding surfaces B28B21/44by projecting B28B21/46by dipping B28B21/48by wrapping B28B21/50Details of compression or compacting means B28B21/52by extruding B28B21/54Mouthpieces for shaping sockets, bends, or like peculiarly-shaped tubular articles B28B21/56incorporating reinforcements or inserts B28B21/563Gaskets B28B21/566Climbing elements B28B21/58Steel tubes B28B21/60prestressed reinforcements B28B21/62circumferential laterally tensioned B28B21/64Winding arrangements B28B21/66Reinforcing mats B28B21/68and applying centrifugal forces B28B21/70by building-up from preformed elements B28B21/72Producing multilayer tubes B28B21/74Producing pipe bends, sockets, sleeves Moulds therefor B28B21/76Moulds B28B21/765Top or bottom rings B28B21/78with heating or cooling means B28B21/80adapted to centrifugal or rotational moulding B28B21/82built-up from several parts Multiple moulds Moulds with adjustable parts B28B21/84Moulds with one or more pivotable parts B28B21/86Cores B28B21/88adjustable, collapsible or expansible B28B21/90Methods or apparatus for demoulding or discharging after shaping B28B21/905Removing from a mandrel B28B21/92Methods or apparatus for treating or reshaping B28B21/925for wrapping B28B21/94for impregnating or coating by applying liquids or semi-liquids B28B21/96for smoothing, roughening, corrugating or for removing burr B28B21/965for grooving or corrugating B28B21/98for reshaping