Abstract: A microwave circuit includes at least one inductive portion and at least one capacitive portion and having a resonance frequency, the microwave circuit including a material which acts as a dielectric for the capacitive portion, characterized in that the material acting as a dielectric includes an active region that is an electrically pumped semiconductor heterostructure having at least two energy levels whose energy separation is close to the resonance frequency of the microwave circuit.

Abstract: A microwave circuit includes at least one inductive portion and at least one capacitive portion and having a resonance frequency, the microwave circuit including a material which acts as a dielectric for the capacitive portion, characterized in that the material acting as a dielectric includes an active region that is an electrically pumped semiconductor heterostructure having at least two energy levels whose energy separation is close to the resonance frequency of the microwave circuit.

Abstract: The invention relates to a guide-bar tube for an automatic lather. The guide-bar tube includes a centering traveler comprising balls distributed in two parallel planes in a manner which allows the centering traveler to be locked either to the guide-bar tube or to the rod of a feed piston. This arrangement allows the displacement of the feed piston both for advancing the bar stock towards the lather and for retraction of the piston towards the rear of the device by vacuum. The presence of the traveller, which is normally mounted on the rod of the feed piston, eliminates buckling and floating of the bar stock and of the feeder rod in the guide-bar tube. This structure results in a considerable increase in the number of turns of the bar and a great reduction of noise.

Abstract: The device comprises essentially a body or shaped piece of cylindrical form and of a circular or polygonal cross section, comprising tubular cavities of different diameters for receiving the bars to be machined of different diameters. The tubular cavities can comprise longitudinal distribution channels for feeding oil under pressure to the bar to be machined. The cylindrical body further comprises indexing grooves at its external periphery, means of distribution of oil at the rear part of the device, an oil collector located at the front part of the device and cavities permitting the return of the oil to a hydraulic group. Reinforcing ribs are provided between the tubular cavities and between the latter and a mantle of the cylindrical body so that the latter has a great moment of inertia which ensures a good stability of the device. The tubular cavities may comprise tubes aligned along the longitudinal axis of the cavities and rotating freely with play in these tubular cavities.

Abstract: The device comprises essentially a body or shaped piece of cylindrical form and of a circular or polygonal cross section, comprising tubular cavities of different diameters for receiving the bars to be machined of different diameters. The tubular cavities can comprise longitudinal distribution channels for feeding oil under pressure to the bar to be machined. The cylindrical body further comprises indexing grooves at its external periphery, means of distribution of oil at the rear part of the device, an oil collector located at the front part of the device and cavities permitting the return of the oil to a hydraulic group. Reinforcing ribs are provided between the tubular cavities and between the latter and a mantle of the cylindrical body so that the latter has a great moment of inertia which ensures a good stability of the device. The tubular cavities may comprise tubes aligned along the longitudinal axis of the cavities and rotating freely with play in these tubular cavities.

Abstract: The device comprises a sectional carrier of closed cross section with a circular bed, a base and channels of distribution and return of oil. A guiding element comprising at least one guiding tube enclosing a bar stock to be machined and a push-piston is removably secured on the bed. The distribution channel communicates through radial openings with the guiding element for delivering to the latter oil under pressure which creates a hydrodynamic bearing supporting the bar stock when the latter is set into rotation by the head stock of the lathe. The sectional carrier has a great rigidity and stability which permits very high speeds of rotation of the bar stock to be machined. The return of oil by closed channels of the sectional carrier is protected against external contamination by impurities or dust.

Abstract: Guide-bar device for a multi-spindle lathe having a barrel indexed by the lathe at each machining operation and secured to a rear part of the lathe. The barrel comprises a central shaft and a plurality of guiding tubes removably supported by a means of disks provided on the central shaft, each guiding tube enclosing a bar to be machined. The bar rotates within the guiding tube in a fluid and is supported by and advanced under the influence of a piston which bears against the rear part of the bar. A fluid distributor is secured to the multi-spindle lathe at the rear part of the barrel. The fluid distributor is connected to at least one source of hydraulic pressure for distributing fluid under pressure into distributing grooves which are connected to a rear part of the guiding tubes for causing the piston to advance in said guiding tube and to a plurality of pipes connected to said guiding tubes for causing a radial injection of the fluid between said bar to be machined and the guiding tube thereof.

Abstract: A process for loading a lathe in which a new bar to be machined is introduced laterally into a guide-bar device in form of a tube during the machining of a last piece at the end of a preceding bar. The new bar causes the ejection of the remnant of the preceding bar by pushing against the rear of the preceding bar. A device for loading a lathe with bars to be machined comprises a guide-bar device in form of a tube having two parts which can be opened for laterally introducing a new bar to be machined into the tube. The bar in the tube is fed by a hydraulically controlled push-piston. Pressure pistons press the two parts of the tube against each other in order to ensure a fluid tight seal. Return pistons are utilized radially move the upper part of the tube at the time of loading.

Abstract: The device comprises a barrel which is indexed by a multi-spindle lathe at each machining operation. The barrel comprises guiding tubes for the bars to be machined which are in rotation in a fluid delivered between the guiding tube and the bar by pipes connected by tubular shafts to a fluid distributor having inlets connected to different sources of pressure. The feed of the bar is controlled exclusively by a feeding piston under the action of the pressure of the fluid delivered by extension tubes located at the rear of the guiding tubes and maintained in alignment with the latter by sliding rings which ensure the tightness between the tubes.

Abstract: A bar stock guiding device for use with automatic lathes comprises two cushions which have the shape of semicylindrical annuli. The cushions are applied against each other in a recess of a freely rotatable sleeve. This sleeve is located between the lathe and a tube of the guiding device which contains the bar of stock fed to the lathe. The sleeve normally rotates with the bar of stock, because the opening appearing between the cushions is adjusted with minimal small free play only to avoid whipping of the bar in the cushions and the propagation of vibrations to the stock bar part extending in the working area of the tools. When the pusher passes through the sleeve, it ejects the cushions out of the sleeve recess. Before this ejection occurs, a braking mechanism reduces the speed of rotation of the sleeve to a substantial extent.

Abstract: Each guiding tube of the equipment provided to guide the different stock bars which can be machined in a given automatic lathe carries collars and a cap member. The collars and cap members of all the tubes of the equipment have the same outer diameter so that any one of these tubes can be secured by means of removable yoking beams on the semi-cylindrical seats of brackets rigidly fixed to one and the same prismatic canal which confers a great stiffness to the guiding tube fixed thereto. Owing to a pin on said cap members entering a bracket notch, bores of the collars and tube mounted in said canal automatically come to lie opposite openings of oil supply conduits to control the pusher feeding the bar to the lathe and to form an oil cushion around that bar.