DOUBLE LAYER ELBOW PRODUCTION METHOD AND APPARATUS

A double layer elbow production apparatus according to the invention is characterized by comprising: a main body having a receptacle defined therein; a pressing guide, which is disposed inside the receptacle of the main body and has a plurality of pressure pieces arranged along a circumference direction, the pressure pieces being formed in a way to make a synchronized sliding movement with neighbouring pressure pieces, respectively, so as to approach one another in a radiation direction; a plurality of springs, which is installed between the pressure pieces of the pressing guide to provide the elastic force in a direction in which the pressure pieces move away from one another; a split mould, which has a plurality of mould elements, each being disposed on a radially outer side of a respective one of the pressure pieces of the pressing guide, inner circumferential surfaces of the mould elements forming the peripheral geometry of an elbow tube bent on a curved path as the pressure pieces of the pressing guide move forwards in the radial direction to bring the mould elements into contact with one another; and a cylinder, which is installed inside the receptacle of the main body and has a cylinder rod for applying an external force to at least one of the pressure pieces of the pressing guide by making a forward/backward movement with respect to the pressing guide. Further, the double layer elbow production method according to the invention is characterized by comprising the steps of: inserting into an outer elbow tube an inner elbow tube made out of heat-treated, wear-resistant steel; and pressurizing the outer elbow tube being bent on a curved path by a plurality of mould elements arranged along a circumference direction so as to adhere the inner circumferential surface of the outer elbow tube onto the outer circumferential surface of the inner elbow tube. Un appareil de production de coude double couche selon l'invention est caractérisé en ce qu'il comprend: un corps principal présentant un réceptacle défini à l'intérieur; un guide de pression, qui est disposé dans le réceptacle du corps principal et présente une pluralité d'éléments de pression agencée le long d'une circonférence, les éléments de pression étant formés de manière à décrire un mouvement de coulissement synchronisé avec des éléments de pression voisins, respectivement, de manière à se rapprocher les uns des autres dans une direction de rayonnement; une pluralité de ressorts, qui est installée