Abstract: In the production of an electrode for an arc furnace from a hardenable electrode paste and in which the arc current is fed to the electrode via a current supply unit, an electrode heater is arranged, in the direction of feeding down of the electrode into the furnace upstream of the current supply unit, said electrode heater supplying thermal energy to the electrode paste for the purpose of baking the latter, the formation of the electrode from the paste taking place in a casing which is not consumed in the arcing.

Abstract: A semiconductor device comprises a semiconductor circuit of CMOS type and an overvoltage protective circuit integrated therewith. The CMOS circuit and the overvoltage protective circuit are formed in one and the same substrate. The device has a contact electrically connected to the substrate. The CMOS circuit has a plurality of inputs. Between each input and the contact connected to the substrate, there is formed and connected in antiparallel a thyristor and a diode. Each thyristor has a firing circuit for ignition of the thyristor at a voltage level which is internally predetermined by the overvoltage protective circuit. In this way, an overvoltage occurring between an arbitrary pair of inputs will cause ignition of the thyristors of the overvoltage protective circuit and short-circuit of the inputs, which efficiently protects the CMOS circuit against overvoltages.

Abstract: The invention relates to a method and to an installation for fitting nuts to a sheet-metal workpiece, by punching the nuts thereinto. In order to provide a rational and flexible nut punching system which can be readily adapted to serve mutually different workpieces, it is proposed in accordance with the invention that the workpiece is securely positioned in a fixture; that a portable nut punching tool is fitted to a tool attachment provided on the wrist of an industrial robot; that the robot positions the nut punching tool sequentially in pre-determined locations on the workpiece to which nuts are to be fitted; and that the nut punching tool is activated in such locations so as to punch nuts securely into the sheet-metal workpiece.

Abstract: A wrist for an industrial robot with a large orientation capacity comprising first, second , third and fourth turnable wrist parts arranged in series with each other. The first wrist part is rotatable about a first axis. The second wrist part is journalled in the first wrist part and is rotatable about a second axis which intersects the first axis. The third wrist part is journalled in the second wrist part and is rotatable about a third axis which intersects the second axis. A tool attachment is rotatably journalled in the third wrist part about a fourth axis which intersects the third axis.

Abstract: A system for HVDC transmission comprises a conductor, stressed by d.c. voltage, which is insulated from a surrounded grounded casing by pressurized SF.sub.6 gas and along part of its length by at least one solid insulator supporting the conductor in the casing and in contact with the gas. By designing the solid insulator as a core of solid insulating material and a coating, provided thereon, with a high surface resistance, it is possible considerably to reduce the dimensions of the casing. The coating consists of a resinous binder containing a powdered filler in the form of chromium oxide or iron oxide, or a mixture of these substances. The coating preferably has a surface resistance between 10.sup.12 and 10.sup.18 ohm/.quadrature. at an electric field strength of 1 kV/mm.

Abstract: A method for controlling the combustion and reduction processes in a black liquor (B.L.) boiler of a paper pulp plant by influencing the feeding of black liquor to the B.L. recovery boiler by means of a B.L. gun. Characteristic of the method is that the average thickness of the layer of the B.L. flow, immediately after the black liquor has left the B.L. gun, is controlled to have a desired magnitude. The thickness of the B.L. layer is obtained in the form of an indirect measure which is defined as the droplet index (=DIX) and is constituted by a relationship between the viscosity, the density and the feed rate of the black liquor and by at least the shape and the opening area, of the B.L. gun.

Abstract: A melt-transfer device for the protected tapping of molten metal from one vessel to another has a tiltable, cylindrical container with a lid, which is at least partially located in a first end wall in the container. The container is also provided with a melt-tapping pipe which is directed substantially tangentially to the container close to the first-mentioned end wall. In the bottom of the container, in a second end wall, a baffle can be arranged to provide a pocket for a magnesium-containing powder fed into the container through the lid when the container is held in a vertical position.

Abstract: A press of pressure cell type comprises a press stand with two opposing force-absorbing elements between which a space is formed. In this space there is located a plate with a recess in which an elastic diaphragm is arranged. The diaphragm forms, together with the plate, a pressure cell. Elongated side supports for the diaphragm are provided at the sides of the said space. A tray insertable into the space forms, together with the plate and the diaphragm, a closed press space. The pressure cell is connected to a pressure medium source. Each side support is formed with an elongated recess, in which there is arranged an expansible membr of elastic material. Each expansible member forms a side support for a press tool located in the tray.

Abstract: A method and apparatus in the production of metallic castings in which metal in molten state is fed from a heated container to a mold or a smaller container via a pressure pipe, a pressure-generating means and a suction pipe. The temperature of the metal, which is present in the suction pipe, in the pressure-generating means and in the pressure pipe, is controlled by heat-generating means in order to keep the metal at a temperature corresponding to or exceeding its melting point, so that the metal is present in molten state during its passage through the pipes and the pressure-generating means.

Abstract: An HVDC power transmission plant with a rectifier station and an inverter station interconnected by a d.c. power transmission line is disclosed. The plant has a communication link for transmitting control information between the stations, at least one of which having at least two parallel-connected converters. If protective blocking of a faulty converter is made in a faulty station during a period when the communication link is not available, the line voltage and line current are temporarily reduced to zero in the rectifier station. In the faultless station, this state is detected and the minimum value of the control angle of the converters of the faultless station is temporarily increased. After output from the rectifier station has been restored, the line current is measured and the current order in the faultless station is set at the measured value, taking account of the current margin.

Abstract: A welding robot having a robot arm which is servo-controlled in a multiplicity of degrees of freedom. At least one servo-system for one of the degrees of freedom is capable of disengaging a part of its feedback network, this part being an integrating circuit, whereby the adjustment from PI-type passes to P-type. The arm then becomes sprung in a direction away for a set-point value with respect to this freedom of movement. When used for welding, the welding gun used and attached to the robot arm is provided with a holding-off or fender arrangement, such as wheels, and is drawn by the servo-system towards a set-point value which it is unable to attain because of the shape of the workpiece, whereupon the wheel is caused to press against the workpiece with spring force, and to follow the shape of a weld joint as it is made, irrespective of whether the joint is uneven or not.

Abstract: A stopper means to prevent melt leaving a metallurgical container, comprises at least one stopper rod and a corresponding tapping nozzle having a tap hole for the melt, a plunger being arranged substantially centrally in the stopper rod and being movable up and down through the tapping nozzle in order to prevent blockage of the tap hole. The device is characterized in that the plunger is movable into the tap hole from a normal position, in which the plunger is positioned completely above the maximum level of melt in the container.

Abstract: A press comprising a press stand, a pressure cell arranged in the press stand with an elastic diaphragm and a tray-shaped tool-carrying member, insertable into the press, in which a forming tool and a workpiece are located. In the inserted position of the tool-carrying member in the press, a closed working space is formed between the pressure cell and the tool-carrying member. The diaphragm is placed in a recess in a press plate. The seal between the diaphragm and the press plate consists of a U-shaped sealing ring having flanges directed inwards towards the center of the pressure cell.

Abstract: The stator winding of a synchronous machine is made as a lap winding or as a wave winding and comprises a plurality of coils, each of which being composed of a top coil half (107) and a bottom coil half (105), the two coil halves, which are series-connected, to each other by means of a connecting device (106), being of identical shape.

Abstract: A robot installation for performing a plurality of assembling or machining operations at a work or assembly station comprises a robot with a rotatable tool support, e.g. a ring or disc, carrying a number of tools. The turning and positioning of the tool support are controlled by control equipment of the robot. The tools are adjustably positioned on the tool support.

Abstract: A series capacitor bank for connection into an electric power supply network is provided with overvoltage protective equipment having two branches connected in parallel with the capacitor bank. The first branch comprises a first zinc oxide varistor in series with a linear resistor and the second branch comprises a varistor with a higher "knee" voltage than the first zinc oxide varistor. The resistance of the linear resistor is preferably of the same order of magnitude as the absolute value of the impedance of the capacitor bank at the operating frequency of the power supply network. The "knee" voltage of the second varistor is at least 1.15 times (and preferably not more than 2.0 times) the "knee" voltage of the first varistor.

Abstract: A fiber-optic sensor for sensing dynamic acceleration is arranged so that the acceleration gives rise to changes in angle between at least one body and the optical axis of at least one lens of graded index type (GRIN lens). At least one optical fiber is arranged to transmit optical energy to and from one end surface of the lens. The optical energy reflected back into the fiber is dependent on the angle and essentially independent of the distance between the body and the lens, and the sensor comprises at least one photoluminescent material so that a part of the optical output signal from the sensor includes a photoluminescent signal.

Abstract: A method for phase-locked sampling measurement of a periodically varying quantity. The samples are designated g(I) . . . g(I-n) and may comprise one complete period or a half of one period. The method involves adapting the sampling frequency and the sample position in relation to the quantity to be measured such that phase locking is attained, and this is done by controlling the time interval between sampling. Whether the sampling frequency needs to be increased, left unchanged or be decreased, depends on a number of decisions depending on the values of samples g(I) and g(I)-g(I-n). A device for carrying out the method is also described.

Abstract: A method for measuring cloud height, in which a train of light pulses is sent from a transmitter into the investigated air space. From each of a number of different height intervals, signals reflected towards a receiver are integrated and measured. The time, the pulse number, the pulse frequency and/or the pulse energy for each height interval are controlled with respect to the energy reflected and received in the receiver from underlying measuring intervals, thus obtaining compensation for losses in the energy of the light pulses in reaching the respective level.

Abstract: A fiber-optic measuring device for measuring physical quantities, comprising a transducer unit and an electronic unit which are interconnected by means of at least one optic fiber. The measuring transducer unit comprises at least two photoluminescent elements, of which at least one is positioned in the ray path of light from the fiber, at least partly behind another element. The physical quantities to be measured are arranged to influence the light transmission between the photo-luminescent elements. The electronic unit includes at least two light sources having different emission spectra which are so chosen in relation to the absorption and transmission spectra of the photo-luminescent elements that one light source is arranged to excite substantially one of the photo-luminescent elements whereas the other light sources at least partly excite the other element or elements.