Abstract: A power limiting device for an electric heating system electronically controlled by a modulating thermostat includes a bistable trigger circuit having an auxiliary temperature sensor preferably comprising a temperature dependent resistor. The trigger circuit controls the modulating thermostat to change the on/off ratio of the heating system as a function of a second temperature parameter to which the auxiliary temperature sensor responds.

Abstract: Noise, fuels and potentially dangerous light emissions generated by a plasma-arc cutting operation are suppressed by carrying out the operation with a solid layer of water surrounding the space between the hot effluent discharge of the torch and the workpiece. To localize the layer of water immediately under the discharge nozzle of the torch, a jacket is provided around the lower end of the torch which continually is receiving and discharging water through a skirt guidance member depending from the jacket thus providing a contained volume of moving water around the space involved which immerses the end of the nozzle. A water layer is also provided under the workpiece which receives water leaking around the skirt member and through the kerf created by the torch under its nozzle. Water from under the workpiece is circulated through a separator to remove unwanted materials introduced by the cutting operation.

Abstract: A system for controlling the temperature of the heater element of a heating apparatus by controlling the resistance of the heater element. In a preferred embodiment, the control system monitors a sensing excitation voltage at the heater element for comparison with a reference voltage, preferably at or near the zero-crossings of the heater power source cycle, and thereupon operates so that power to the heater element is always applied and terminated at zero-crossings of power cycle. In a preferred embodiment, the controller is arranged to permit only integral cycles of power to be applied to the heater element to avoid a DC bias buildup and undesirable loading of the power line.

Abstract: Control of a heating system by means of modulating electronic thermostats. Two thermostats are coupled by an opto-electronic device in order to meet the requirements with respect to the "bi-junction" heating system. A double power-limiting device moreover allows the ratio of the maxiumum power dissipated by the two resistors with which the heating convector is equipped to be varied.

Abstract: Disclosure is made of an electron beam welding gun, wherein an anode unit is connected to a cathode unit having a sealed housing, in which there is arranged a cathode assembly. Said cathode assembly comprises a high voltage tubular insulator, whereupon there are mounted sealed leads. The inside of said sealed housing is filled with a liquid dielectric and cooled by a cooler. At least part of the outer surface of the high-voltage tubular insulator is part of the surface of the sealed housing's internal cavity.

Abstract: An electrical current limiting fuse having longitudinally spaced support members for fuse elements. The support members comprise a central portion having radial arms supported thereon. Coiled fuse elements are disposed between complementary radial arms of the longitudinally spaced support members. The fuse elements are not coiled around each support member as a whole to completely peripherally encompass it but merely are held at one position on the periphery.

Abstract: Disclosure is made of a cathode assembly of an electron beam welding gun, wherein in a holder's sleeve, which is mounted an a current lead, there is arranged a disc cathode. Arranged in the cavity of said current lead, coaxially therewith, are two more current leads. The latter two current leads are concentric to each other; in said current leads there is secured a flat coil with a central end bent at a perpendicular to the coil's plane. Said central end, bent at a perpendicular to the coil's plane, is corrugated along its axis and installed in a current lead constructed as a rod having a stepped cavity extending along the rod's axis. The outer turn of said coil is arranged in another current lead which envelops the above-mentioned current lead and is constructed as a tube with an internal annular recess at its end, which receives the outer turn of said coil.

Abstract: Disclosure is made of a cathode assembly of an electron beam welding gun, comprising a current lead, wherein there is arranged a heating cathode which is coaxial with said current lead. Next to said heating cathode and coaxially with it, in a holder's sleeve there is arranged a disc cathode. The holder's sleeve is provided with a central orifice in its bottom to receive the disc cathode. On the internal surface of said sleeve, on the side opposite to the bottom, there is provided a cone-shaped recess widening towards the disc cathode, which recess receives a split ring of a refractory material, intended to press said disc cathode against the bottom of the holder's sleeve.

Abstract: A thermionic heater cathode assembly for an electron-beam gun, comprising a disc cathode made of a highly-emissive material and disposed near a metal ribbon filament the thermionic portion whereof has a W shape, the distance between two apices of said thermionic portion being 0.6 to 0.8 of the disc cathode diameter and the depth of the valley between the apices constituting 0.5 to 0.6 of said diameter.

Abstract: The heater shutdown circuit is connected between an electric current source and a heating element in an electric heater and is operable to shut off the flow of current to the heating element when the heating element reaches a predetermined temperature and to maintain the flow of current shut off after the heating element cools to a temperature below the predetermined temperature. The heater shutdown circuit will maintain the electric current shut off until the heater shutdown circuit is disconnected from the current source for a predetermined period of time after which the heater shutdown circuit can be re-energized. The heater shutdown circuit includes a control circuit connected to the current source, a switching circuit coupled between the control circuit and the heating element, and a current sensing circuit coupled between the heating element and the junction between the control circuit and the switching circuit.

Abstract: A metallized substrate is flexed to conform to the surface of a segment of a right circular cylinder. The metallized substrate is arcuately rotated and a planar apertured mask is simultaneously moved linearly in spaced tangential relationship to the flexed substrate. A laser beam is directed through the apertured mask to traverse a line formed by the intersection of a plane parallel to the planar apertured mask and tangent to the flexed metallized substrate. As the metallized substrate and the apertured mask are moved, the laser beam is continuously reciprocated along the line to raster scan the metallized substrate through the apertured mask to remove metal therefrom in a desired pattern.

Abstract: Electron beam machining apparatus of the dynamic seal type, characterized by upper and lower fixed plates for fixedly clamping a workpiece therebetween, which plates define upper and lower vacuum chambers; a movable plate disposed on said upper fixed plate so as to be movable in the working direction, said plate defining a movable chamber which communicates with said upper vacuum chamber, said upper and lower vacuum chambers and the movable chamber providing a working chamber of the apparatus; inflatable seal members for said upper and lower vacuum chambers; said upper and lower plates defining auxiliary vacuum chambers located outwardly of and encircling their respective fixed vacuum chambers, an upper wall of said upper vacuum chamber defining an opening in the form of a V-shaped groove which extends in the working direction of V-belt seal, and by a belt seal guide tube mounted on said movable plate and extending in the working direction, to enclose the electron gun, said V-belt fitting into said groove in

Abstract: Apparatus for externally welding a seam along abutting lengths of pipe with the pipe being supported on site in position, e.g., on the ground, the apparatus having laser transmitting means which includes optically coupled individual reflectors supported for orbital movement about the seam, the optically coupled individual reflectors serving to provide a folded multiple reflection path to the seam for transmitting a focused laser beam onto the seam along a predetermined section thereof below the pipe axis.

Abstract: The laser light emitted from a laser generator is cast on two prisms which have the same angle of deflection and are supported rotatably by support members so as to be rotated about the optical axis of the laser light in the opposite directions at the same speed. The laser beam scanned through the rotations of the two prisms is focussed on a work piece by a convergence lens so that the work piece is linearly scanned for laser-working. Moreover, there are provided a pair of scanning sections, each comprising such a pair of prisms as described above, the scanning sections being so arranged that the directions of scanning the laser beam by the respective sections may be perpendicular to each other. The rotational speeds of the prisms of each scanning section is so controlled as to subject the spot of the laser beam to two-dimensional scanning for laser-working a work piece.

Abstract: A process for deep micro-engraving of a material includes the steps of superpositioning a plurality of elementary layers of respectively alternating indices on the material. Each of the layers is individually transparent to a predetermined wavelength in vacuum, and has an optical thickness equal to one quarter of the predetermined wavelength. The process further includes forming a plurality of openings in the elementary layers; the openings correspond to regions to be engraved on the material, and uncover selected portions of the material. The material is then illuminated by a laser beam of sufficient power to engrave, by sublimation, the uncovered material portions. The laser has the predetermined wavelength, and the plurality of layers form a mirror for the laser beam, which have a relatively high threshold of damage from the laser, and absorb substantially no power from the laser beam.

Abstract: Electric process heating control includes a combination of (1) pyrometric temperature controller providing a DC control signal wherein the ratio of "on" time to "off" time is proportional to the deviation of temperature from set-point value and to the duration of such deviation, (2) phase-angle-fired power controller, and (3) current limiter for altering the phase angle firing of the power controller.

Abstract: A semi-automatic feed laser apparatus includes a laser beam focused on a workpiece affixed to a pattern template which is urged by the operator against rotatable guide means rotating at a predetermined rate to feed the workpiece smoothly under the laser yet permit manual override of the feeding operation to accommodate irregularities or surface non-uniformities in the workpiece. Advantageously, the guide means include a hollow cylinder-like member and drive means operably connected thereto for rotating the guide cylinder. As preferably embodied, one end of the guide cylinder is adapted to contact the template while its other end is coupled to an exhaust system for removing debris and combustion particles immediately from the work area. Moreover, the axis of the cylinder may be generally aligned with the laser beam to allow harmless defocusing of the laser radiation.

Abstract: An electrical furnace has a plurality of electrical heaters and a control unit carried by a frame. A rigid lead unit is carried by the frame and has rigid lead means directly and electrically interconnected to terminals of the heaters and terminals of the control unit, the rigid lead unit itself having terminals for electrically interconnecting the rigid lead means to power source leads whereby the power source leads are directly and electrically interconnected to the terminals of the heater and the control unit by the rigid lead means without the need for auxiliary wiring. The control unit includes an electrical sequencing switch construction having a plurality of electrical switches for sequentially operating the heaters, the switch construction having a temperature sensing unit operatively interconnected to the switches for moving and holding the same in open conditions thereof when the temperature sensing unit senses a high temperature condition of the heaters.

Abstract: Process and apparatus for simultaneously pressurizing a fuel rod having a plug in one end, welding a plug in the other end and sealing a gas pressurizing orifice therein in a single operation. A weld chamber is provided which accommodates one end of a seal rod having a plug fixed in the rod end by a friction fit. A mechanism pushes the fuel rod into the weld chamber which is then pressurized to force gas through a plug orifice into the fuel rod. During subsequent rotation of the rod, an electrode in the weld chamber forms a weld puddle which bridges the end plug-fuel rod interface and the plug orifice to thereby weld the plug in the rod and seal the plug orifice in a single operation.

Abstract: In a chromatography system of the type including an oven for the chromatographic column, and an electric heater for controllably heating the oven, an improved system is disclosed for controllably opening and closing the oven door to enable a fully controlled heat leak, thereby to stabilize the oven temperature at a desired set point. A signal, which is indicative by first or second conditions of an oven temperature above or below the set point, is generated. A heater power control responsive to one of the signal conditions can effect heating of the oven. A bi-directional door motor and actuator means is provided for opening and closing the oven door over a prescribed operating range, and this means is enabled to operate for a predetermined period upon the signal in its first or second condition departing from preset threshold values for a predetermined period, in consequence of which the opening or closing of the oven door is effected in incremental steps.