Showing papers on "Electric resistance welding published in 1982"

Process for the production of a composite metal part and products thus obtained

Abstract: The present invention relates to the production of metal parts whose core and surface must have different characteristics. Its subject comprises firstly a process for the production of a composite metal part by coating or hard-surfacing a metal core of low-alloy structural steel with a harder metal layer composed of a high-speed chromium-tungsten or chromium-molybdenum steel or a high-speed steel containing chromium associated at the same time with a plurality of elements such as tungsten, molybdenum, vanadium, and cobalt, this process being at the same time characterized in that this high-speed steel has a hardness higher than 57 Rockwell C, in that the low-alloy steel which constitutes the metal core is selected to be compatible with the said high-speed steel, in that the said high-speed steel is applied exclusively in the form of a prealloyed powder, and in that the coating or hard-surfacing of the core with this powder is effected with the aid of one of the welding processes of the follow-group: welding by means of a transferred or semi-transferred arc plasma torch, or welding by means of a laser torch, the operation of coating or hard-surfacing by welding being followed by heat treatment. Another subject of the invention comprises the products obtained by the abovedescribed process. It is particularly applicable to the production of rolls for cold rolling mills, rolling or forming rollers, shear blades, wear plates, and armor plates.

Apparatus and method of phase control for resistance welding and other resistive-inductive loads

Abstract: A computer-controlled welding apparatus includes a phase-controlled resistance welding circuit (A) for selectively conducting pulses of a welding current to a workpiece (B) and a control circuit (C) for controlling the conduction of the welding current. The control circuit includes a line clock generator (30) for determining the beginning of each voltage half line cycle and a conduction sensor (34) for determining whether or not a contactor (14) is conducting current to the workpiece. A microcomputer (40) is preprogrammed with a plurality of power factor correction curves, each of which represents weld current vs. firing angle for a fixed hangover angle. The computer is programmed to select one of the power factor correction curves. If the preceding half line cycle was conductive, the program selects the curve which corresponds to the hangover angle of the preceding half line cycle. If the present half cycle is the first conductive half cycle in a weld, the program selects the curve corresponding to a hangover angle of about 87°. During pulsation welding, the curve is selected based upon the hangover angle of the most recent conductive half cycle and the number of nonconductive half cycles therebetween. During each half cycle, the present angle (duration since the beginning of the half cycle) periodically addresses the curve and a corresponding weld current is retrieved. The retrieved weld current represents the weld current which would be produced if the container were rendered conductive at the present time, i.e., the present weld current. A comparator (86) compares a preselected weld current for the present half cycle with the present weld current. When the present weld current becomes coincident with the preselected weld current, the contactor is rendered conductive.

Method for welding with the help of ion implantation

Abstract: The invention is a method for welding together two parts with the help of ion implantation. The method comprises weakening the chemical and atomic bonds of the surface and near surface atoms of at least one of the surfaces to be welded together by ion implantation techniques. The ion implanted surface may then be cold or diffusion welded to the surface of the other part using conventional methods. The method is particularly applicable to welding together parts of dissimilar metals normally difficult to affect a satisfactory weld.

Method and apparatus for controlling resistance welding

Abstract: Method of controlling resistance welding to obtain high quality welds in which the pressure between the electrodes (2a, 2b) holding the materials (1a, 1b) to be welded is controlled so that the resistance value between the two electrodes (2a, 2b) is a predetermined value, and the welding current is regulated so that the voltage between the electrodes is a predetermined value, and the time during which the welding current flows is controlled to a fixed period.

A new approach to the weldability of nickel-base As-cast and power metallurgy superalloys

Abstract: The repair of nickel-base superalloys such as those used in the first and second stages of the rotating sections of a gas turbine is examined. Welding is affected by stress and temperature levels of the blade, wall thickness, and material composition. Steps to achieve crack-free welds include preheating above 600C (1112F) for GTA and plasma arc welding and above 900C (1652F) for EB welding. It is concluded that crack formation can be prevented by controlling the cooling rate during welding; that hardness measurements provide useful results for crack-free welding using GTA, plasma, friction, and electron beams; and that small differences in chemical composition and homogeneity can have a decisive effect on weld behavior.

Method of welding titanium alloy parts with titanium insert

Abstract: A method of welding opposite end surfaces of two titanium alloy parts kept in alignment by a high energy-density welding process such as electron beam welding, laser beam welding or TIG arc welding, characterized by closely interposing an insert member of either practically pure titanium or Ti-Al binary alloy containing up to 3 Wt % of Al. Owing to thorough alloying of the inserted titanium with the constituents of the fused base metal, the weld metal in a weld joint obtained by this method is sufficiently high in both strength and toughness. By an optional postwelding heat treatment, the strength of the weld metal can further be enhanced.

Tubular composite arc welding electrode for vertical up welding of stainless steel and nickel-base alloys

Abstract: In a tubular composite electrode for depositing stainless steel or nickel-base alloy weld metal, satisfactory performance in vertical up welding is achieved through the inclusion in the electrode core of a slag mix comprising 15 to 60% weight percent zirconium dioxide.

Consumable electrode type arc welding device

Abstract: PURPOSE:To provide a titled welding device which improves welding performance and the efficiency in welding work by the constitution wherein the waveform of welding current is pulsed to form a spray arc and a separate filler wire is fed under electrical heating into the arc. CONSTITUTION:Welding current is flowed from a power source 24 through a tip 16 to a consumable electrode 10, which is fed by a roll 12 driven by a motor 14, to generate an arc 20 between the electrode and a base material 60. The adequate pulse waveform corresponding to the feed speed of the electrode 10 is formed in the welding current by a frequency setter 46, a pulse width setter 48 and a switching element 34 to make the droplet from the electrode 10 into a spray. A filler wire 26 is at the same time fed into the arc 20 while it is heated by part of the welding current supplied from a power feeder 32 to adjust the penetration rate of the molten metal. The heating current for the wire 26 is controlled by a frequency setter 46, a pulse width setter 50, a current comparator 59, a switching element 36, etc. so that said current is kept at <=1/2 of the welding current and is made zero during the quiescent period of the pulse.

Resistance welding with pressure control in response to deviation between welding voltage and time varying reference values therefor

Abstract: A system for resistance welding in which the welding voltage between the electrodes is controlled by changing the pressure applied to the electrodes or the firing phase angle of the welding current in accordance with a reference voltage curve or a reference voltage integration curve. The system comprises a voltage sensor, a reference voltage generator, a differential amplifier, and a pressure control device, or a calculating unit for determining an appropriate firing phase angle of the welding current. The system thus improved can ensure a stable, good welding quality, since the welding voltage is always controlled by a series of optimum welding voltages, during the welding process, in accordance with a reference voltage curve with respect to time, preferably in terms of cycles of the welding current.

Development and Application of Dabber Gas Tungsten Arc Welding for Repair of Aircraft Engine, Seal Teeth

Abstract: Dabber TIG welding can be defined as a modification of an automatic TIG welding system. Modifications, both mechanical and electronic, combine to cause an intermittent filler wire feed to the molten weld puddle. This interrupted action allows for momentary cooling of the weld puddle. Energy input, as heat, for a given time span is reduced by this action. In addition the interruption allows solidification of the puddle with resultant narrow, uniform bead. This weld mode is characterized by shallow heat affected zones and precise weld build up configurations. This paper describes the application of this procedure to Gas Turbine Seals.Copyright © 1982 by ASME

Method of an apparatus for welding together metal components

Abstract: In having a method of welding together metal components (A,B) a high restraint geometry (as defined in the Specification) the components are urged into abutment and a high energy density weld is effected at a location in said abutment by means such as a focussed laser beam (L). In order to compensate for the high restraint geometry of the components which prevents them from deformation such as to accommodate welding stresses, an additional force (J) is applied, for example by a roller (K), to urge the components together adjacent to the position at which the weld is effected. The method is advantageously employed to form a continuous elongate weld between a plateform and web of a brake shoe.

Electro-slag welding process for irregular sections

Abstract: An electro-slag welding method and apparatus has been developed for butt-joint welding of steel rails or other metallic pieces having irregular cross section, in which the head and the web of the rail is surrounded with a conventional water cooled copper mold and the flange area is surrounded by a ceramic lined crucible. In addition to the conventional single central welding electrode, two or more electrodes are inserted through the lids of the ceramic crucible adjacent the outer ends of the rail flange so as to reduce the total welding current required to produce a complete flange weld and spread the welding energy, thereby reducing excess power and overheating at the central electrode, resulting in better metallurgical quality welds.

Manufacture of high toughness electric welded steel pipe

Abstract: PURPOSE:To manufacture an electric welded steel pipe whose weld zone has superior toughness in the manufacture of an electric welded steel pipe by electric resistance welding, by heating and cooling the weld zone under specified conditions, and tempering the whole pipe CONSTITUTION:An electric welded steel pipe is manufactured by a conventional method The weld zone of the pipe formed by electric resistance welding is heated to a temp in the temp range from the Ac3 transformation point preferably to about a temperature 200 degC higher than the Ac3 transformation point, and it is cooled at 15-30 degC/sec cooling rate from >=800 degC-<=500 degC The whole pipe is then tempered at 450 degC - the Ac1 transformation point Thus, an electric welded steel pipe having superior toughness at the weld zone as well as the base metal is manufactured with high work efficiency at a low cost

Arc welding robot control system

Abstract: An arc welding robot control system includes a control console where a plurality of points on a workpiece taught by a teaching box and a welding voltage, a welding current and a welding speed set by a key board to be specified to each of the taught points are stored in a central control unit and displayed on a cathode ray tube, and a welding electric source for selectively delivering two sets of a welding voltage and a welding current which are specified for a pulsed and a short arc welding process respectively. With the pulsed arc welding process displayed, a set of normally open contacts disposed within the central control unit is closed to cause an electromagnetic contactor disposed within the welding source to operate the source with the that process. Otherwise the contact set is maintained open to operate the source with the short arc welding process.

Method and apparatus for shaping beads of welded steel section

Abstract: In manufacturing steel sections by high-frequency resistance welding, weld beads are produced along the weld line of the material. However, rolls disposed in the neighborhood of the welding end point squeeze the red-hot weld beads into a uniform shape.

Method and apparatus for making an electric resistance welded tube

Abstract: A conductor is installed along a Vee-angle part of a tube to be welded for producing an electric welded tube by high frequency resistance or induction welding. The conductor is set closely above the Vee-angle part. A high-frequency current having about the same phase as a phase of a high-frequency current for welding is supplied to the conductor. This controls the distribution of the current density on mating surfaces of Vee-angle part so that the welding current does not concentrate in the upper and lower edges of the tube, thus making uniform the current density and heating in the Vee-angle part.

Control device for resistance welding machine

Abstract: PURPOSE:To prevent the flow of eddy current in remaining circuits despite disconnection of one of secondary circuits by subjecting the output voltage of a delay circuit to A/D conversion as the waveform resembling to that of the current of load. CONSTITUTION:The voltage applied to the primary side of a welding transformer 3 is conducted to an A/D converter 6 through a primary delay circuit 10 and phase regulating circuit 10' of RC, and a gain regulating circuit 11. It is digitally converted there and is fed back to a microprocessor 7. In the microprocessor 7, the target value of the current programmed in a program box 8 and the fed back current value are compared, and calculated, and the firing angle of a thyristor 2 is controlled in such a way that the fed back current value goes equal to the target current value. Since the waveform of the voltage at both ends of the capacitor C is not affected by the disconnection of the secondary circuit of a welding transformer 3, the flow of eddy current in remaining circuits despite disconnection of one of the secondary circuits is obviated.

Aluminum alloy for butt resistance welding with superior stress corrosion cracking resistance at joint

Abstract: PURPOSE:To provide an Al-Mg alloy having high stress corrosion cracking resistance at a joint formed especially by butt resistance welding and consisting of a prescribed percentage each of Mg and Cu and the balance essentially Al. CONSTITUTION:Said Al-Mg alloy consists of, by weight, 3.0-5.0% Mg, 0.05- 1.00%, especially 0.10-0.50% Cu and the balance Al with inevitable impurities. This alloy is semiconductinously cast and hot rolled as usual, and it is optionally cold rolled and subjected to final annealing to obtain a soft rolled plate. The resulting plate has superior strength, high formability and high stress corrosion cracking resistance at a joint formed especially by flash butt welding. Accordingly, this alloy is most suitable for use as a structural material for a 2-piece wheel for a car, and it is preferably applied to a seam welded pipe, machine parts, etc. each having a butt resistance weld zone.

Precise positioning for a welding electrode which follows a three dimensional weld path

Abstract: A welding apparatus which includes a welding electrode and a filler wire assembly. The welding electrode and the filler wire assembly are fixed together and are to move along a weld path on a workpiece. The weld path may either take a regular or an irregular shape. The welding electrode is mounted on a welding electrode bracket which is rotatably mounted on a rotational axis upon a housing. The rotational axis of the filler wire assembly in respect to the welding electrode is precisely controlled so that just the tip of the filler wire is continuously located just forward (along the weld path) of the tip of the welding electrode regardless of the direction of movement of the welding electrode along the weld path. Three dimensional, preprogrammed movement along an X-axis, a Y-axis and a Z-axis can occur between the welding electrode and the workpiece. The welding electrode is also permitted an additional amount of limited movement along the Z-axis which is not programmed. This limited movement is to maintain the electrode at a constant distance from the workpiece within the weld path. This is obtained through an automatic voltage control system which is to hold the arc voltage constant.

Hot wire type arc welding system

Abstract: In a welding apparatus employing a switching element between a power source and a filler wire, a protection circuit operates to discontinue the function of the switching element when a short-circuit is detected between, for example, the filler wire and a welding electrode, so that the switching element is protected from damage due to an overcurrent.

Butt welding method of high purity ferritic stainless clad steel

Abstract: PURPOSE:To obtain a welded joint part which is excellent in both corrosion resistance and a mechanical property, by welding a base metal part of clad steel with a same metal, subsequently, performing butt-welding on a cladding member by a build up welding according to a low dilution welding method by use of a welding rod having the same composition as a cladding material. CONSTITUTION:In case of welding of clad steel whose cladding material is high purity ferritic stainless steel containing 16-21wt% Cr and 0.75-3.5wt% Mo, the same metal welding of a base metal part is completed, and thereafter, a cladding member is butt-welded by building up to >=2 layers in accordance with a low dilution welding method by use of a welding rod having the same composition as the cladding material. As for welding of said cladding material, if necessary, the first layer is welded by a ferritic stainless steel welding rod containing 25-33wt% Cr and 0.75-3.5wt% Mo, and the residual part is welded with a same material or the first layer is welded by a welding rod having the same component as the cladding material, and therefore, said welding can be executed, as well.

Process for welding coated plates

Abstract: Interposing a coating-compatible strip material between a coated plate to be welded and a welding electrode that contacts that plate during the welding operation so that a coating-compatible film is applied to the plate during the welding process to prevent the removal of the protective coating of the plate. A device for performing the process includes support means for supporting a supply of strip material and guides for interposing the strip material between the plate and the welding electrode that contacts that plate during the welding operation. The strip material may be contained in a cassette which is adapted to be attached to the device.

Method for controlling welding current

Abstract: A method for controlling a welding current in a resistance welder which phase-controls an A.C. power supply voltage by a thyristor to control the welding current to a target value. Prior to supplying the welding current, a test current is supplied to measure a power-factor angle of a load. A plurality of curves representing relations between the welding currents and control voltages to a phase-shift pulse generator for a plurality of power-factor angles of the load are presets and one of the curves is selected in accordance with the selected power-factor angle of the load. A variation of the A.C. power supply voltage is measured. A period of a pulse generated by the phase-shift pulse generator is controlled based on a value determined in accordance with the selected curve and the measured variation of the A.C. power supply voltage to control a firing angle of the thyristor.

Compact tool for automatic MAG spot welding

Abstract: In a compact tool for automatic MAG spot welding, all of the elements are located close to the welding zone and a single set of props both support the articles to be welded and provide a negative electrical current contact A welding head is slidably supported upon a base which is connected to a robot arm by quick release couplings The base further supports a welding wire reel and brake while the head supports the torch and a welding wire drive device Props on either side of the welding zone press the article to be welded and provide negative electrical current contact

Method and apparatus for observing welding strength in spot welding

Abstract: PURPOSE:To detect strength of spot welding at high accuracy by taking out only true component of voltage between electrodes that acts as an effective component in spot welding. CONSTITUTION:Voltage generated by a zinc plating layer is detected from voltage between electrodes impressed between two poles of an electrode of a welding gun. Induction noise component and welding gun electrode resistance component are removed from the voltage and detected voltage, and remaining component is integrated. The integrated value of effective component is obtained by subtracting a value obtained by integrating minimum voltage during conducting time from this value. This is compared with a preset reference voltage value, and welding strength is observed by the result of comparison.

Multielectrode submerged arc welding method

Abstract: PURPOSE:To form a weld bead of deep penetration at low heat input and to improve the shape of the bead, by providing a suitable back step angle to a preceding welding core wire and a succeeding welding core wire and supplying a filler wire into a molten pool from the final succeeding welding core wire. CONSTITUTION:Welding core wires 1, 2, 3 into which electrode tips are inserted are supplied into the powdery flux F which is sprayed beforehand on a base material A, while the wires are disposed in tandem. 10-30 deg. back step angle alpha is given to the preceding wire 1 among the wires 1-3, 3-20 deg. back step angle beta is given to the succeeding wire 2 and further, a forward angle gamma is given to the succeeding wire 3. Arcs are generated between the forward ends of the wires 1, 2, 3 and the material A, and the material A is moved in the arrow direction whereby the material A is melted successively and a molten pool C is made. The molten pool is solidified successively to form a molten metal B, by which a weld bead is obtained. The intrusion of the molten metal increased by the melting of a filler wire 4 into the part right under the arcs is prevented and the disturbance of the melting of the material A by the molten metal is thus prevented. The decrease in the penetration depth is obviated even if the wire 4 is supplied from backward.

Welding method for laminated plate

Abstract: PURPOSE:To perform projection welding easily by providing a projection to the joining place of one member and conducting electricity under pressure in welding laminated plates consisting of an inside layer of a thermoplastic resin and both outside layers of metallic foils and a metallic member. CONSTITUTION:Laminated plates consist of an inside layer 1 of a thermoplastic resin and both outside layers 2, 3 of metallic sheets. A projection 5 is provided to a metallic member 4 of the place to be joined. The joining parts of the laminated plates and the metallic member are pressed with an electrode 6 and a pressure receiving plate 8, and the metallic foil 2 of the laminated plates is pressed with an electrode 7. In this state, electric current is flowed between the electrodes 6, 7, whereby resistance welding is accomplished.

Ultrasonic welding process and apparatus

Abstract: In the ultrasonic welding process according to the invention, an additional element 3, besides the ultrasonic welding probe (2), is used as a holding-down device which vibrates at the same ultrasonic frequency as the ultrasonic welding probe 2 but with reduced amplitude, is in contact with areas outside the bearing surface of the ultrasonic welding probe 2 and dampens these externally located surfaces or parts or masses which are in contact with the ultrasonic welding probe itself or lie directly next to the bearing surface of the ultrasonic welding probe 2. Thus areas or parts of the object to be welded which protrude and/or have a relatively large mass and/or areas with a small wall thickness are prevented from fracturing or breaking off or the object to be welded is prevented from being detrimentally affected during the welding operation. Furthermore, an apparatus for carrying out the process according to the invention is specified, the additional element 3 being arranged in the interior of a hollow ultrasonic welding probe 2. The disadvantages with regard to the vibration behaviour of the ultrasonic welding probe which occur when bores are formed in the wall of the ultrasonic welding probe are avoided by the bores being sawn from the welding surface or towards the welding surface and by the welding surface of the welding probe being split up into welding-surface segments.

Iron-based alloy for welding spheroidal graphite cast iron workpieces.

Abstract: To produce welds on workpieces which are made at least partly of spheroidal graphite iron, a welding-material alloy is to be created which can be processed to form welding rods or the like and which permits welding under normal conditions. In the process, a readily machineable weld is to be obtained which has adequately high extension and toughness at high strength. An alloy on an iron basis for use in the autogenous and electric fusion welding of workpieces made of spheroidal graphite iron is proposed which consists of a low-manganese, low-carbon silicon steel as a base material, the manganese content of which is set at <0.2% and the carbon content of which is set at <3.0%. Apart from silicon with a proportion of 2.5 to 3.2%, copper up to 1.0% as well as molybdenum up to 0.5% are also added to it. An alloy with a manganese content of <0.1% and a silicon content of 2.8 to 2.9% is preferred. The drawing properties of wire material can be improved by an aluminium addition of 0.1 to 2.0%.