Abstract: Pulsatory burner which is mounted in the water room (12) of a hot water boiler comprising a combustion chamber (14) with a neck (17) provided as an air inlet, and a nonreturn valve (18) controlling the air flow through the air inlet to the combustion chamber. An outlet (40, 41) for hot water from the water room (12) is provided around the neck (17) for the cooling thereof.

Abstract: An object is manufactured of a powdered material by isostatic pressing of a body (10), preformed from the powdered material, whereby the preformed body is surrounded by a casing (16) which at least for the main part is transferred to molten phase, before the isostatic pressing is carried out while sintering the powder. As material in the casing there is used glass or a material forming glass when being heated and containing 48-52 percent by weight B.sub.2 O.sub.3, 46-50 percent by weight SiO.sub.2 and 1.5-2.5 percent by weight Al.sub.2 O.sub.3. It can be removed from the finished object by water or water vapor and has a low coefficient of thermal expansion at temperatures below the melting temperature of the glass. To counteract the penetration of molten glass from the casing into the preformed body, a barrier layer (18) may be arranged on the preformed body inside the casing. (FIG.

Abstract: When manufacturing an object of powdered material by isostatic pressing of a body (10), preformed from the powdered material, with a gaseous pressure medium, the preformed body is provided with a casing (19) of glass which is made gas-impermeable by heating before carrying out the isostatic pressing. Inside the glass casing there is arranged on the preformed body a barrier layer (11) which counteracts the penetration of melted glass from the enclosure in the preformed body. The barrier layer is built up of at least two layers, of which one layer (12) at least substantially consists of powdered boron nitride and one layer (13) of a mixture of powdered boron nitride and a powdered material with the ability, upon contact with glass from the casing in melted form, to make a layer containing boron nitride tighter.

Abstract: A casting (e.g. of aluminum or aluminum alloy) is made at least approximately free from pores by being subjected, in heated state, to isostatic compression in a liquid pressure medium. A rapid pressing operation of under one minute can be achieved if the casting is placed in a container, the container and the casting are heated to the required compression temperature before they are thereafter placed in a press chamber of a fast-acting press. When liquid pressure medium is fed to the press chamber and the necessary pressure is applied thereto, the pressure medium flows into the interior of the container via a number of channels in its wall and is simultaneously heated to the necessary temperature, prior to its contacting the casting.

Abstract: In the manufacture of an article of ceramic material, for example a bladed turbine wheel of silicon nitride, there is first formed a plurality of article parts, at least one of which is a shaped powder body formed from powder of ceramic material mixed with a plasticizer, after which the plasticizer is driven off by a suitable heating operation. The article parts are then assembled together into a configuration conforming to that of the article to be manufactured, and the assembled article parts are surrounded with a gas-impermeable layer, for example a layer of glass. Finally, the assembled parts are isostatically pressed at elevated temperature to form the assembled article parts into a dense, homogeneous article.

Abstract: An object is manufactured from a powdered material by isostatic pressing of a body, preformed from the powdered material, with a pressure medium, whereby the preformed body, in which at least the surface layer consists of a ceramic material in the form of a nitride, is surrounded by a casing which is rendered impenetrable to the pressure medium, before the isostatic pressing is carried out and the powder sintered. As the material in the casing there is used boron oxide or a glass containing boron oxide or a material forming glass while being heated, in which the content of boron oxide is sufficiently high for the glass--or the glass formed during heating--to be removable by water. The preformed body surrounded by the casing is subjected to a heat treatment for the formation of boron nitride on the surface of the preformed body, before the isostatic pressing is carried out. The casing is removed from the finished product by means of water or water vapor.

Abstract: Disclosed is a method for manufacturing an object of silicon nitride. In the method, a body preformed from silicon nitride is surrounded with a casing which is permeable to gas. Upon heating, the casing is transformed into a layer which is impermeable to a pressure medium which is used during isostatic pressing of the preformed body while a pressure outside the casing is maintained which is at least as high as the pressure of the gas which is present in the pores of the preformed product. After the casing has been made impermeable to the pressure medium and the preformed body has been enclosed therein, the isostatic pressing is carried out while the body is simultaneously sintered.

Abstract: An object of ceramic or metallic material is manufactured by isostatic pressing of a body preformed from a powder of the metallic or ceramic material, the preformed body (10) then being embedded in glass, for example in a mass of glass particles (16) in a vessel (15) which is resistant to the temperature at which the sintering of the metallic or ceramic material is carried out, the material embedding the preformed body being transferred to a melt having a surface limited by the walls of the vessel, below which surface the preformed body is located, and a pressure necessary for the isostatic pressing of the preformed body then being applied on the melt by a gaseous pressure medium.

Abstract: An object of ceramic or metallic material is manufactured by isostatic pressing of a body preformed from a powder of the metallic or ceramic material, the preformed body (10) then being embedded in glass, for example in a mass of glass particles (16) in a vessel (15) which is resistant to the temperature at which the sintering of the metallic or ceramic material is carried out, the material embedding the preformed body being transferred to a melt having a surface limited by the walls of the vessel, below which surface the preformed body is located, and a pressure necessary for the isostatic pressing of the preformed body then being applied on the melt by a gaseous pressure medium.

Abstract: Disclosed is an improved method for manufacturing an object of silicon nitride. In the method, a body preformed from silicon nitride powder and enclosed in a casing of glass is isostatically pressed with a gaseous pressure medium in a pressure vessel at a temperature required for sintering of silicon nitride. After pressing and sintering are completed, the pressure and the temperature in the pressure vessel are adjusted such that the temperature maintains the glass in a plastic state and the pressure in the pressure vessel is below the partial pressure of nitrogen gas for silicon nitride at that temperature so that the glass casing is blown up around the body and the body is freed from or can easily be freed from the glass casing.

Abstract: Disclosed is a mandrel for a high pressure tube extrusion press. The mandrel comprises a tip member providing a tip adapted to be positioned in the die opening of the press to present an annular gap for tube extrusion, and a carrier for the tip member. The carrier has a threaded central tip member receiving bore for threadably receiving a threaded segment of the tip member therein. A divided ring shaped element is disposed between a flange on the tip member and the carrier in an annular space provided at the mouth of the bore to facilitate the assembly and disassembly of the mandrel and prevent inadvertent separation of the tip member from the carrier.

Abstract: Method and apparatus for plastically de-forming material in a high pressure cylinder, the material being pre-formed into a mandrel billet with an attachment portion and a piston at respective opposite ends thereof and interconnected by an intermediate portion having a smaller cross section than the piston. Holder structure releasably mounted within the high pressure cylinder adjacent the pressure chamber retains the mandrel billet and includes securing means at one end for retaining the attachment portion and engagement means at the other end for slidably engaging the piston. Pressurization of the pressure chamber generates an increase in the pressure medium which acts on the transition surface between the intermediate portion and the piston to cause an elongation of the intermediate portion of the mandrel billet.

Abstract: A press for the hydrostatic extrusion of metallic billets to form tubes and other profiles includes a hollow high pressure cylinder having a removable liner which forms the inner wall thereof and which encloses the internal pressure chamber. To protect the removable liner from fatigue breakdown, the inner wall of the liner is coated with a protective coating of an organic polymer and a metallic tube is located adjacent the protective coating and concentric therewith, between the protective coating and the internal pressure chamber.

Abstract: In the hydrostatic extrusion of tubes in a press which has a pressure chamber containing a high pressure cylinder, a pressure generating portion insertable into the cylinder, a die arranged in the cylinder and a mandrel axially fixed in relation to the die and composed of a carrier portion and a tip, and in which the tip forms with the opening in the die a gap in which a tubular billet is shaped into a tube by hydrostatic extrusion, in connection with the insertion of the tubular billet, a seal is produced initially between the mandrel and the hole in the billet at a point between the front part of the mandrel carrier and the hollow wall of the billet. This may be done by producing a constriction of the front end of the hole in the billet before the mandrel is inserted therein or by upsetting the billet against the die.

Abstract: A press for hydrostatic extrusion includes a pressure chamber for enclosing a pressure medium which is formed of a high pressure cylinder, a pressure generating piston, a die and a die support and seals. The die support includes an exchangeable support ring which engages the end surface of the liner and bridges the gap between the liner and the die. A metallic sealing ring is arranged within the liner in engagement therewith, forming a gap between the inner surface of the sealing ring and the outer surface of the die or die support. The die support has a groove in its upper surface which contains a sealing member against which the edge of the metallic sealing ring engages. The lower outer corner of the metallic sealing ring is bevelled to form a space which communicates with the outside of the press.

Abstract: An electrical generator for projectiles and the like comprises a piezoelectric element housed in a cavity through which air is forced by missile movement. A reed-like tongue in the cavity has one end captive, its other end near a ram air inlet that terminates in a nozzle outlet which is aligned with the tongue and is so configured as to enable the ram air to impart vigorous vibration to the tongue. The piezoelectric element has a vibration transmitting connection with the tongue, near the captive end of the latter.

Abstract: A press for hydrostatic extrusion of tubes includes a die with an opening and a mandrel which together with the opening forms a gap in which a tubular billet is shaped into a tube. The mandrel is formed of a carrier with a bore therein and a tip which is attached in the bore and projects into the die opening. A plate is positioned between the inner end of the tip and the bottom of the bore and is made of a material with at least substantially the same E-modulus as the material of the carrier. The innermost end of the mandrel has an enlargement thereon forming a shoulder and the material of the character is compressed against the tip beneath the shoulder so as to prevent axial movement of the tip.

Abstract: For detecting leakage past a high pressure seal which seals a space in which a high pressure exists, there is arranged outside the high pressure seal a collection space for pressure medium which leaks into the space and a device is provided connected with the space to detect changes in the pressure or temperature therein and to produce a signal or to stop the press. The detecting device may be an insulated cable which seals the space on the side remote from the high pressure seal and which may be broken by pressure within the space, thereby interrupting an electrical circuit.

Abstract: A press for hydrostatic extrusion of tubes includes a high pressure cylinder axially displaceable in a press stand with a die insertable into the cylinder and a pressure generating punch insertable into the cylinder to generate the pressure for extrusion. A mandrel is carried by a rod which passes through the pressure generating punch. Seals are provided between the mandrel and the pressure generating punch and between the pressure generating punch and the pressure cylinder. These seals are so located that during the actual extrusion they are arranged in the same transverse plane.