Showing papers on "Arc welding published in 1974"

Anode Phenomena in Vacuum and Atmospheric Pressure Arcs

Abstract: This paper summarizes recent experimental data related to anode phenomena in both vacuum and atmospheric pressure arcs. Currents in the range 10A to 3OkA are discussed, and particular emphasis is placed on the effect of plasma flow from the cathode. For vacuum arcs this plasma flow is the directed motion of metal ions from the cathode spots. These ions reduce the anode voltage drop, and maintain a diffuse anode termination. At atmospheric pressure the ion flow is impeded by gas-atom collisions. However, a plasma flow towards the anode can result from magnetic pinch forces at the constricted cathode termination. In the absence of plasma flow, the anode termination constricts to a vigorously evaporating anode spot. For a typical non-refractory electrode such as copper, the spot operates at a temperature close to the boiling point irrespective of the gas pressure. The spot temperature is dictated by the balance between electrical input power and evaporative losses. These anode phenomena are discussed in relation to vacuum switchgear, arc welding and arc furnaces.

Welding system provided with wire feed and arc control

Abstract: In the process of arc welding with electrode wire feed there are many parameters which influence the quality of the welded joint. The welding system proposed provides considerable quality improvement, particularly in short-circuiting arc welding, reduces the dependence of the welding process upon the skill of the welder and greatly simplifies setting of the apparatus. A characteristic regulating parameter of the welding process is regulated so that the mean arc power remains substantially constant. Embodiments given by way of example illustrate ways of measuring and controlling the mean arc power, which, according to the insight on which the invention is based, is the factor which determines quality.

Method and apparatus for non-consumable electrode type automatic arc welding

Abstract: A method and an apparatus for non-consumable electrode type automatic arc welding in which the length of an arc produced between a non-consumable electrode and a workpiece which is being welded, is automatically controlled to an optimum value by means of an electric drive motor for driving an electrode according to a signal obtained by proportionally integrating or multiplying the voltage difference between the arc voltage detected by using an integrating element and the set reference voltage.

Automatic fixed position pipe welding

Abstract: Automatic fixed position pipe welding is carried out by gas-shielded electric arc welding with a novel flux-cored electrode wire having a low-carbon sheel sheath containing a core filling of, by weight, 16-17 percent ferro manganese, 10-11 percent ferro silicon, 1-4 percent manganous oxide, 1/2-1 percent potassium aluminum fluoride, and the balance rutile. The wire exterior is shiny and metallic-appearing, and the wire is configured to have folded-in edges.

Arc welding torch

Abstract: An improved arc welding torch is provided wherein the welding torch comprises in combination a body portion having at one end an inlet for the introduction of inert gas; a head portion attached to the body portion at the end remote from the inlet for the introduction of inert gas and having at the opposite end an outlet for the discharge of inert gas, the head portion being in electrical contact with the body portion; a first conduit through the body portion for passage of the inert gas therethrough and a second conduit in the head portion for the passage of inert gas therethrough, the first and second conduits being in fluid communication; means for passing electric current through the body portion and head portion; and electrode means in electrical contact with the head portion, the improvement wherein the body portion includes a plurality of co-axial ball and socket joints and means associated with the same to maintain the ball and socket joints in any configuration to which the plurality of coaxial ball and socket joints are deformed. This allows the arc welding torch, and the electrode in particular to have access to portions of the workpiece which would be normally inaccessible.

Multiple arc welding device and method

Abstract: Apparatus and method for welding girth joints in pipelines and similar structures, of the general type described and claimed in U.S. Pat. No. 3,806,694, is improved by adding to the normal or conventional head, on its frame, a second or supplemental welding head with its own independent wire electrode, electric power and shielding gas supply. The second head is mounted on an adjustable support for accommodating work pieces of different radius or for varying arc positions. Oscillating means for spreading the molten metal across the width of the joint, as normally provided for the single welding head in the patent mentioned, are adapted to operate the second head as well and to vary its amplitude of movement. Separate means are provided for adjusting the spacing between each head and the work and also for lateral adjustment to align the heads with the plane of the joint. By these means, the number of stations required for a multiple pass operation, on thick wall pipe, for example, may be reduced. By operating two welding heads on each of two or more carriages, welding equipment requirements may be cut nearly in half, with beneficial effects on the weld, due to improved thermal effects. Either head may precede the other; cantilever means provide stability for the head mounted most remotely from the frame.

Apparatus for underwater arc welding

Abstract: A housing chamber for use in underwater arc welding is constructed in the form of a portable hollow cylinder open at one end and having a side opening in which is movably mounted a welding gun for effecting a welding operation on a workpiece through the open end. The interior of the housing chamber is illuminated and a viewing plate slanted relative to the axis of the cylinder closes the other end. The chamber is provided with means for introducing gas under pressure to purge the chamber of water. An L-shaped vent tube adjacent the viewing facilitates purging the housing chamber of water. The vent tube is rotatably adjustable relative to the housing chamber to control the amount of gas discharged. A porous rubber gasket member is provided between the workpiece and the open end of the cylinder to permit escape of gas therethrough to facilitate relative movement between the cylinder and the workpiece.

Voltage sensor circuit for an arc welding wire feed control

Abstract: A sensor circuit coupled to an arc welding system and responsive to the arc welding voltage including an oscillator and means for varying the frequency thereof in response to the arc voltage, light emitting means responsive to the oscillator frequency, and detecting circuit means responsive to the light emitting means for providing a DC voltage proportional to the arc voltage.

Nuclear fuel elements sealed by electric welding

Abstract: A nuclear-fuel assembly has an end plug and is sealed except for a small diameter axial bore in the plug. A welding electrode of the same material as the plug has an end ground to a point. The tapered end is then inserted into the bore. Before the bore is sealed the assembly is filled with an inert-gas at high pressure. An electric welding current is then directed through the electrode and the plug to seal the bore.

Beam carriage type automatic arc welding apparatus with welding head tracking mechanism

Abstract: Automatic arc welding apparatus in accordance with the present invention comprises a welding carriage movably supported by a horizontal guide beam, which carriage supports a plurality of arc welding heads for forming welds on a generally horizontally disposed work piece, wherein the welds may be of compound curvature. The welding head mechanisms are supported by compound connection apparatus that defines three interrelated axes that are cooperatively related to enable an electrode support to which welding wire electrode is automatically fed to precisely follow a joint of compound configuration that is established between angularly related portions of the work piece. Additionally, the welding head mechanisms are movable both vertically and laterally to facilitate proper positioning thereof to the work piece being welded.

Process and apparatus for the performance of arc welding and overlaying, preferably submerged arc

Abstract: Arc welding and overlaying, particularly with strip electrodes, and particularly for overlaying by the submerged arc welding process with strip electrodes, can be regulated as to the distribution of arc energy by using strip electrodes which are run through male and female gears so that the current input of the electrodes is adjusted as to uniformity across the width of the overlay path.

Plasma-MIG arc welding

Abstract: A plasma-MIG welding method and device in which a stream of oxidizing gas, such as argon plus 2% oxygen, is introduced into the plasma arc in the region of the plasma nozzle orifice. This improves the stability of the MIG arc, and higher welding currents can be used, especially with negative polarity on the electrodes and the plasma and MIG arcs.

Flux-coated arc welding electrode

Abstract: Nickel-chromium-silicon steel electrode for arc welding provides maraging stainless steel weld deposits having desirable strength, toughness and corrosion resistance in age-hardened condition. Electrode arc can be shielded with inert gas or with lime-cryolite-titania flux containing specially controlled proportions of manganese.

Method of underwater welding

Abstract: The invention relates to a welding torch for welding underwater and to a method of underwater welding using the welding torch. A high speed stream of water is directed from a nozzle on the welding torch obliquely onto a member or members to be welded to form a flared-out curtain of water. Gas is injected into the volume enclosed by the curtain of water to create a gaseous atmosphere and welding is carried out in the gaseous atmosphere.

Electrode composition and welding method for arc welding steel

Abstract: A wire electrode for use in arc welding comprising a metal to be deposited on a substrate and further comprising a flux, said flux comprising:

Pulsed arc welding apparatus

Abstract: A pulsed arc welding system is disclosed in which improved performance is obtained through the use of positive switch control in the welding transformer secondary winding. The switch means is programed through solid-state gate drivers which are in turn controlled for controlled rectification on each half cycle by a phase control, the operation of which is initiated by sensing the secondary winding voltage. Thus, it is possible to accurately control a high current interval and a low current interval with precision to obtain optimum welding and weld control. The time intervals for high level and low level welding current are also precisely controlled through digital counting techniques which permit a full range of control from zero to one hundred per cent high current mode of operation and a high current period as well as a low current period varying from 1/60 to 1-4/5 seconds.

Relation between mechanical properties and microstructure in CRE Type 308 weldments

Abstract: A shielded metal arc (SMA) Type 308 stainless steel pressure vessel test weld with the controlled residual elements (CRE) boron, titanium, and phosphorus was tensile tested and creep tested at temperatures to 650/sup 0/C (1200/sup 0/F). Improved ductility in tests lasting several thousands of hours, compared to that of standard welds, is associated with the absence of interphase separation. Systematic variations in microstructure and mechanical properties throughout the weld and in the heat-affected zone are due to thermal and mechanical cycling during the welding process. Anisotropic deformation, that is related to local substructure and preferred crystallographic orientation, occurs.

Rotating arc welding method and apparatus

Abstract: Apparatus for welding parts, such as pipes, end to end by means of an electric arc which is caused to rotate along the adjacent edges of the pipes. Two separate magnetic fields are used to cause the arc to follow a spiral path along the edges so that pipes having a wall thickness greater than one quarter of an inch may be welded.

Arc welding process and apparatus

Abstract: An arc welding process and apparatus utilising an electrode and a counter-electrode between which a column of plasma forms. A first unidirectional current source is located between the electrode and the counter-electrode, and a second unidirectional current source is located between the counter-electrode and the member to be welded. These two sources simultaneously pass the two unidirectional currents.

Welding machine supply system - using transistorized frequency changer and transformer or/and rectifier

Abstract: An electric welding appts. includes a frequency change which converts the mains a.c. supply voltage from a 50 Hz frequency to a frequency of up to 25000 Hz. A transformer produces from the supply voltage (380 V) a voltage for arc welding (15-40 V) or for resistance welding (2-20V) or, by an added rectifier, to a d.c. voltage. This results in an appts. of small weight (5-15 Kg) if fully transistorised. The equipment is easy to handle and has a universal application.

Weld fill height regulating system for arc welding apparatus

Abstract: Means are provided for maintaining a uniform height of deposited weld material in an electrical arc welding apparatus of the kind having a welding head driven by a travel motor along a juncture between two workpieces which are to be joined. A first signal, indicating departure from a desired fill depth, is produced by sensing variation of the welding current from a predetermined normal magnitude. The first signal is applied to summing junction together with a predetermined selectable reference signal of opposite polarity so that the two signals cancel out as long as the desired weld fill height is being maintained. Upon a departure from the desired weld fill height an output signal from the summing junction activates a servomotor which adjusts the speed of the travel motor as necessary to maintain the uniform weld depth. Means are further provided for assuring continuance of the welding head movement in the event that the melt should be lost because of proximity to an edge of the workpiece or because of an opening therein.

Flux-cored welding wire for gas-shielded electric arc welding

Abstract: A novel flux-cored welding wire for gas-shielded electric arc welding is described characterized by a shiny, metallic-appearing surface on a low carbon steel sheath and containing within its core as essential flux ingredients 6-20% ferro manganese, 6-20% ferro silicon, 1-20% manganous oxide, 1/2-5% of a flouride compound, and the balance rutile. The wire is especially useful in out-of-position welding to produce sound welds combining good strength and high notch toughness at subzero temperatures.

Process for welding aluminum and aluminum alloys in horizontal welding position

Abstract: Aluminum and aluminum alloys are welded in a horizontal welding position in which the base metals to be welded are vertically disposed in abutting relationship with the welding groove opened sidewise by oscillating the tip of the welding electrode in the widthwise direction of the abutted base metals and welding the base metals while maintaining the angle formed by the surface of the molten pool and the electrode on the advancing side thereof greater than 90°. The surface of the molten pool as used herein is defined as one which is parallel to the crater surface of the weld which results upon termination of welding by extinction of the welding arc.

Arc welding rig for tubular articles - has excitation coils producing circular arc revolving in annular chamber filled with inert gas

Abstract: Annular workpieces (rings, tubes) are arc welded without any addition of filler metal or of electrodes by an arc which moves on a closed circular track inside a closed chamber. The two pieces of the chamber contain two excitation coils and have a seal ring at their sliding joint. Inert gas is introduced tangentially into the annular chamber.

Arc-welding power source

Abstract: A multi-phase SCR-rectifier controlled arc welding power source having improved operating and internal protection characteristics. The transformer has an improved core and winding design having a built-in internal reactance and a core arrangement which is scrapless and very compact. The output has an adjustable, drooping, volt-ampere curve such that the welding current may be readily preset or adjusted to any desired value. The power source includes an unusually high inductance for a three phase source so as to give a very stable arc with a control circuit having provisions to properly control the conduction angle of the SCR's so as to overcome the disadvantages of such a large choke on starting or short circuiting so as to give optimum welding characteristics. Further the ratio of short circuit current to welding current is controlled and decreases with an increase in the welding current. Protection against damage of the power source is provided in the event of extended short circuit or overload. Compensation for line voltage variation is also provided.

Grounding device for electric welding

Abstract: A grounding device designed to fit into the weld groove between two adjacent work pieces, such as lengths of pipe, is held in place by having one end anchored under a firm holder in form of a tight band surrounding one of the work pieces and annularly spaced therefrom Contact at the joint is maintained by use of a selectively movable eccentric which can be released to break the contact and for shifting the ground to another location The grounding contacts (a plurality are preferred) is shaped to fit the surface of the welding grove accurately, minimizing resistance at the points of contact and avoiding pitting due to arcing

Resistance welding parameter profile for spot welding aluminum

Abstract: As tip force is increased, there is a larger tolerance in the variation of the other welding parameters, i.e., current and weld duration where good weld quality is obtained. Longer weld current duration reduces the tendency to have cracks appearing in the sheet under the electrodes. There is a near linear correlation between welding current and shear strength which is independent of the number of weld cycles and tip force used.

Electron beam, laser beam and plasma arc welding studies

Abstract: This program was undertaken as an initial step in establishing an evaluation framework which would permit a priori selection of advanced welding processes for specific applications. To this end, a direct comparison of laser beam, electron beam and arc welding of Ti-6Al-4V alloy was undertaken. Ti-6Al-4V was selected for use in view of its established welding characteristics and its importance in aerospace applications.

Magnetically-moved-arc welding appts. - with individual magnets in welding plane and surrounding workpieces

Abstract: The same poles, pref. south poles, of the magnets surround the closed weld path and are pref. united in a closed path by connection to a radially split ring. The magnets may be electromagnets and individual magnets may be supplied with different currents. The appts is esp. for welding tube ends and rings and produces a strong field concn. even when welding small components.