Abstract: One end-closed ceramic double wall-structural tubes are disclosed, which each include inner and outer tube members, and plural supporting portions integrating the outer and inner tube members. One end of the outer tube member only is sealed. A process for producing such tubes is also disclosed, which includes the steps of extruding a green ceramic double wall-structural tube comprising inner and outer tube members, and a plurality of supporting portions integrating the outer and inner tube members; drying the green ceramic tube; grinding off the inner tube member and the supporting portions in a given depth from an end face of the dried tube, inserting a porous member made of an organic material into the ground-off portion of the tube inside the outer tube member; pouring and depositing a slurry into the tube on an axially outer side of the porous member; and drying and firing the thus one end-sealed ceramic tube.

Abstract: A method for producing a sleeve having a closed end by extruding a forming material from a mouthpiece. A core member is arranged in position in the mouthpiece and has a piston member detachably provided in a tip end of the core member. The piston member has an air communication aperture. On the other hand, an outer die is arranged in the mouthpiece for forming an outer configuration of the closed end. As a result, an annular space is formed by the mouthpiece, core member and outer die. The forming material is then supplied into the annular space and extruded to form the closed end of the sleeve. After the outer die has been removed from the mouthpiece, the piston member is caused to slide relative to the mouthpiece and at the same time the air is blown into an inside of the closed end through the air communication aperture of the piston, while the forming material is further supplied and extruded from the mouthpiece to form the closed end sleeve.

Abstract: One end-closed ceramic double wall-structural tubes are disclosed, which each include inner and outer tube members, and plural supporting portions integrating the outer and inner tube members. One end of the outer tube member only is sealed. A process for producing such tubes is also disclosed, which include the steps of extruding a green ceramic double wall-structural tube comprising inner and outer tube members, and a plurality of supporting portions integrating the outer and inner tube members; drying the green ceramic tube; grinding off the inner tube member and the supporting portions in a given depth from an end face of the dried tube, inserting a porous member made of an organic material into the ground-off portion of the tube inside the outer tube member; pouring and depositing a slurry into the tube on an axially outer side of the porous member; and drying and firing the thus one end-sealed ceramic tube.

Abstract: A breathing apparatus includes: a vessel member having a mouth piece and internal influx chamber; a tubular communication member having opposite ends connected respectively to the intake and outgo ports of the vessel member in such a manner that the vessel member and the communication member define a circular passage for a respirable gas; an oxygen-supplying mechanism for supplying the circular passage with the respirable gas; a pair of check valves, disposed respectively at the intake and outgo ports of the vessel member, for limiting the flow of the respirable gas in the circular passage to a single direction so that, when the person breathes into the influx chamber, the respirable gas in the influx chamber is introduced into the communication member through the outgo port and, when the person inhales through the mouth piece, the respirable gas in the communication member is recycled into the influx chamber through the intake port; and an outlet port for discharging excess respirable gas out of the circular

Abstract: A process for sealing an end face of a ceramic tube is disclosed. The process includes the steps of inserting a porous member made of an organic material into one end of the ceramic tube after the ceramic tube is dried, and pouring and depositing a slurry into the ceramic tube on an axially outer side of the porous member, followed by drying and firing. The porous member is shaped to meet an inner shape of an end of the ceramic tube to be sealed. The slurry exhibits the same coefficient of thermal expansion as that of the ceramic tube during firing.

Abstract: A ceramic cylindrical body just after extrusion-molding is held on a porous support at a floating state by air pressure and dried while supplying air to the inside of the ceramic cylindrical body.

Abstract: A ceramic body is continuously extruded through a die of an extruder and held on a porous support at a slightly floating state by air pressure jetted from pores of the support.