Showing papers on "Welding published in 1979"

Modern Welding Technology

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Thermoplastic welding sleeve

Abstract: A body sleeve (4) obtained by widening of a pipe is arranged on a mandrel on which spaced spirals (7) of a resistance wire (6) are wound. By heating the body sleeve (4), it is fixed onto the winding. An electric current circulating in the resistance wire causes the thermoplastic to melt and flow around the spirals for enclosing the latter completely by expansion. Further, the material forms projecting sections (8, 9) next to the winding. Hence, the spirals (7) are protected against accidentals shocks and the recessed end parts (5) of the inner wall which have been deformed inwards during manufacture require no further forming.

Austenitic solidification mode in austenitic stainless steel welds

Abstract: The micro- and macrostructures of about 50 different stainless welds of the AISI/AWS 300 series are analyzed. The results indicate that in welding condition corresponding to a typical SMA welding those and only those welds in which the ratio Creq/Nieq≲1.48, where Nieq and Creq are the nickel and chromium equivalents on the Schaeffler diagram, solidify with the austenite as the primary or leading phase and the delta ferrite, if any, formed from the rest melt between growing cells or cellular dendrites of the austenite. At room temperature these welds are characterized by a regular general microstructure, soft forms of the ferrite and relatively large compositional differences mainly caused by solidification.

Welding helmet lens assembly

Abstract: A protective welding lens assembly for use as the eyepiece of a welding helmet in which the lens assembly can be changed from a light-transmitting condition to an essentially opaque condition of very small light transmission, and vice versa, in response to an electrical signal and wherein the electrical signal for changing the light-transmitting characteristics of the lens assembly is controlled by energy emanating from the mouth of the user of the welding helmet. Preferably, the lens assembly comprises a liquid crystal light shutter; however any lens assembly can be used which can be electrically actuated to change its light-transmitting characteristics. A transducer is disposed within the welding helmet so as to be in front of the mouth of the welder when the helmet is positioned over his face. The transducer can comprise either a microphone responsive to sound from the welder's mouth or a pressure transducer responsive to blowing from the welder's mouth. An electrical signal generated by the transducer is then used to control the light-transmitting characteristics of the lens assembly.

Simple theory of free-burning arcs

Abstract: Analytic formulae are derived from the controlling physical equations to give the principal characteristics of free burning arcs. Predictions of arc radius, voltage, central temperature, electric field and centre plasma velocity are in reasonable agreement with published experimental results for arcs in air from 1 A to 20,000 A at a pressure of 1 atmosphere and an electrode spacing of 1 cm. The theory enables useful predictions to be made for applications of arcs in welding, switchgear and arc furnaces.

Method for welding hard metal

Abstract: Disclosed is a method for welding wear-resisting hard metals directly to iron base members which are slide or wear members of machinery. Hard metals comprising a tungsten carbide and a binder consisting of 15 to 30% by weight of Ni and/or Co is employed as said hard metals. A Ni alloy metal containing no Cr is used as a filler metal.

Method and apparatus for automatically controlling arc welding

Abstract: Disclosed is a method and apparatus for automatically controlling arc welding, wherein pieces of optical information provided by at least two bands of different wavelengths of light radiated from a weld area being arc-welded under predetermined welding conditions are alternately picked up by an optical device to extract various weld factors representing the actual status of the weld area from these pieces of optical information, and the extracted weld factors representing the actual status of the weld area are compared with the desired values of the weld factors representing the desired status of the weld area to compute the error or errors of the welding conditions, so that the welding conditions can be corrected on the basis of the detected error or errors of the welding conditions, whereby the weld factors can be controlled to the desired values.

Apparatus for machining material

Abstract: The gaussian energy distribution common to all laser beams is a serious handicap in most laser beam applications for machining material, such as for drilling, welding and the like. This is especially true in welding extremely thin metal sheets, as in the manufacture and assembly of the transducers of modern magnetic disk files. According to the subject invention, a laser beam is directed to a glass cone or axicon which converts the gaussian energy distribution of the laser beam to one more uniform in cross-section. Depending on the distance of the workpiece from the exit side of the axicon, the energy distribution of the radiation impinging onto the workpiece will be either uniform, saddle shaped or annular cross-section. It has been discovered that saddle shaped or annular energy distributions are optimal for welding very thin metal sheets by a laser beam since the heat dissipation in the center of a welding spot is a minimum and that at the periphery of the laser beam depends on the material, size and shape of the workpiece, which parameters can be matched by adjusting the distance between the axicon and the workpiece.

The Effect of Autogenous Welding on Chloride Pitting Corrosion in Austenitic Stainless Steels

Abstract: Potentiostatic and isothermal immersion tests have been used to investigate pitting corrosion in the weld metal of low carbon (<0.03%C) austenitic stainless steels. The experiments were co...

Method and apparatus for arc welding of metal plates from one side only

Abstract: An apparatus for arc welding of a pair of spaced steel plates from one side only using a grooved back-up plate which gives a good weld bead shape on the under side, gives high linear welding speeds, and avoids contamination of the deposited weld metal by the metal from the back-up plate. A pair of consumable electrodes connected in electrical series between the output terminals of the power source and with one connected by an independent connection to the workpiece are advanced into the weld gap on lines of movement which intersect at a point above the lower surfaces of the plates so that an arc is maintained between the electrodes spaced from the base of the back-up plate groove. A separately energized electrode trails the first two electrodes and deposits a weld bead on the first deposited weld metal while it is still hot.

Effects of fume particles from stainless steel welding on sister chromatid exchanges and chromosome aberrations in cultured chinese hamster cells

Abstract: The frequencies of sister chromatid exchanges (SCE) and chromosome aberra-tions were examined in cultured Chinese hamster cells (Don) exposed to two sorts of fume particles collected from different procedures of stainless steel weldingIt was confirmed that the frequencies of SCE and chromosome aberrations in the cells treated with these fume particles increased with increasing fume doses within the range of the fume concentration tested The fume partticles collected from manual metal arc (MMA) welding were more powerful than those from metal inert gas (MIG) welding In order to cause the same increase in SCE frequency the fume particles from MIG welding needed to be about 100 times as much as those from MMA welding The fume particles from MMA welding showed a higher so-lubility of Cr than those from MIG welding The amount of dissolved Cr from the former was about 60 times as much as that from the latter when culture medium was used as a solvent Small amounts of Mn, Ni, Fe and Mg were also detected in the supernatants of both fume suspensions There were no significant differences in the amounts of these metals as was found with Cr when comparing MMA weld-ing with MIG welding The frequencies of SCE and chromosome aberrations were also increased by the addition of the supernatants of these suspensionsFrom these results, it was assumed that dissolved hexavalent Cr may be involved in the cytogenetic effect of the fume particles from stainless steel welding

Laser/ultrasonic welding technique

Abstract: A non-contact laser/ultrasonic welding technique for strengthening the con laser weld by the addition of ultrasonic cavitation and cleaning. A high powered laser applies heat to a weld joint to produce a melt. The output of the laser, or a second laser, is amplitude modulated to generate acoustic waves in the melt. The improved interdiffusion of the melt and the homogeneity of the weld joint result in an improved quality laser weld.

Vibratory welding of battery components

Abstract: Thermoplastic battery cover and container piece parts are fused together using vibratory energy, particularly ultrasonic welding, in which the horn has a depending skirt extending along an outer wall of the container and which serves to maintain the cover and container in mutual alignment and simultaneously contain the flow of the melt (flash). In another aspect, a particular interference joint between the components is described featuring a continuous ramp of 50-70 degrees and producing an interference fit for an improved weld. The invention is also directed to a cell or battery formed according to the method of the invention, as well as the horn.

Production and Applications of Microwave Surface Wave Plasma at Atmospheric Pressure

Abstract: Surface wave microwave excitation structures can be used to produce relatively long plasma columns at atmospheric pressure. Characteristics of this new versatile plasma are given. Applications such as trace gas analysis by optical emission spectroscopy, production of flames of various compositions, welding, and spectral lamps are presented.

Automatic presettable welding system

Abstract: An automatic presettable welding system which enables the user to preset the arc voltage and wire feed speed to precise predetermined values without either energizing the wire with arc voltage or initiating the wire feed. A meter (A) is supplied with an appropriate signal so the readout corresponds to the desired wire feed speed or the desired arc voltage and these same signals are supplied to wire feed speed or arc voltage comparative circuits (C, E) which then function to energize a wire feed motor (B) or an arc welding power source (H) to the precise wire feed speed or arc voltage indicated on the meter. Means are provided for controlling the acceleration of the wire feed drive motor and a controlled initiation of the arc voltage at the beginning of each weld. Overload, overvoltage and undervoltage or over or under wire feed speed and other protective circuits (G, F) are provided with appropriate delays in the functioning thereof to ensure fully automatic and satisfactory welding.

Apparatus for the remote control of mains operated DC and AC welding machines

Abstract: Apparatus for the remote control of mains operated DC and AC welding machines without any additional cable to the working place, comprising a portable regulating device adapted to be connected into the welding current circuit between the electrode or the electrode holder and the workpiece or a clamp therefor. This device selectively generates different control signals in the welding cables when receiving a current supply through the welding cables, and a regulating circuit in the welding machine is adapted to receive these control signals through the welding cables from the regulating device and to cause regulation of functions in the welding machine or in association therewith in response to the control signals. The regulating circuit comprises a decoding circuit which in response to the pulse-shaped control signals in the welding cables, is adapted to produce regulating signals for the welding machine depending upon the number of pulses or the code of pulses being provided by the regulating device, and a blocking circuit which prevents the formation of regulating signals in the decoding circuit when currents of the same order of magnitude as the welding current flow in the welding cables.

Apparatus and method for refinishing turbine blade airseals

Abstract: A method and apparatus for restoring airseals on gas turbine blades and vanes. A worn or damaged airseal is removed by abrasive belt grinding perpendicular to its length to create a stub. Then a piece of material is joined to the stub, as by welding. Next the airseal weldment is contoured using abrasive belting, perpendicular to the weldment length. The invention is particularly advantageous for the repair of components having two airseals of different dimensions. A single two-position fixture is usable to remove old airseals and to refinish airseal weldments. Refinishing is accomplished with a contoured belt; the contour is chosen to be intermediate, but within the tolerance of, the contours of the first and second airseals. As a result, airseals are economically restored in short runs.

Method of ensuring the maintenance of constant quality of spot welds

Abstract: A method of improving the reproducibility of the welds in an electric spot welding machine comprises prior to the initiation of a welding operation passing a preheating current of lower magnitude than the welding current through the parts to be welded. When either the total electrical workpiece resistance of the parts to be welded has fallen below a given limit or when its rate of decrease is slower than a predetermined limit the changeover from preheating current to welding current is effected.

Hand-operated remote control unit and mounting structure for an arc welding machine

Abstract: A hand-operated remote control unit has a housing containing a rotary potentiometer whose shaft carries a pinion which is driven by a rack having a spring loaded push button attached thereto. An eccentric cam is mounted on the potentiometer shaft adjacent a microswitch in which the cam surface is in contact with the switch when the push button is in its unactuated position. When the push button is actuated, the cam rotates releasing the switch, and the rack and pinion varies the resistance of the potentiometer to vary the welding current. A plurality of hat section holders are positioned on different surfaces of the housing for mounting an adjustable ring-shaped clamp having bayonet extensions thereon which fit into the hat section holders. The adjustable ring-shaped clamp which has a set screw therein is adapted to be adjustably mounted on the handle of the welding torch. The adjustable clamp may be moved up and down to a desired position on the welding torch and the welding torch may be rotated 360° therein. The plurality of hat section mounts into which the clamp fits permits further adjustment and placement of the welding torch to adapt it to reach difficult places and at the same time permit operation of the push button with various digits of the hands. Accordingly, finger tip control of the welding current is achieved without the necessity of moving the torch even while wearing bulky insulating gloves.

Apparatus for forming bags of thermoplastic material

Abstract: In an apparatus for forming and separating the side edges of plastic bags of the type which have opposed interlocking closure strips, an intermittent transport device transports a half-tube of thermoplastic sheeting to a welding device. The sheeting is stopped while welding is performed. At a milling station upstream of the welding device, a milling apparatus is actuated while the half-tube is stopped to mill off a short length of each of the opposed closure strips at a position which coincides with the position at which welding will later be performed.

Automatic voltage compensation for digital welder control system

Abstract: An automatic voltage compensation control for a microprocessor controlled resistance welder system includes a digital voltmeter for measuring the line voltage cycle by cycle and associated circuitry to compensate the welding current in response to the measured line voltage in a manner which tends to hold the welding current constant and independent of line voltage variations. The digital voltmeter consists of a voltage-to-frequency converter coupled to a counter. The output of the voltage-to-frequency converter which is proportional to the line voltage is accumulated for the period of one cycle of the line frequency. This produces in the counter at the end of each measurement interval, a number of counts proportional to the average line voltage. The microprocessor using the count obtained adjusts the welding current by altering the timing of the firing points of the SCR contactors used to control the welding current.

Arc welding pipe apparatus

Abstract: Pipe welding clamp apparatus, including a pair of clamp assemblies, one being of conventional design and the other being of a special design permitting access to the axial space between the clamp assemblies so that internal welding assemblies may be disposed partly within said axial space and partly at a location opposite said special clamp assembly from said axial space. Each welding assembly includes a relatively large welding electrode reel and an electrode feeder at said location, communicated with a torch assembly in said axial space through a flexible tube. Each torch assembly includes means for torch position adjustments angularly and radially, and includes novel means for oscillating the torch so that a wider root weld is formed which will bridge the welding gap between adjacent pipe ends in spite of torch position misalignment and in spite of irregularities in pipe alignment and welding gap width. Novel clamp locator means and wheel support means are also disclosed.

Cored type welding electrode

Abstract: A cored type welding electrode which enables good penetration, has an improved range of welding voltages, produces low smoke and provides a weld deposit having good impact properties. The flux contains larger than normal quantities of basic oxides, controlled maximum amounts of acidic or amphoteric oxides and deoxidizers, and a very carefully controlled maximum and minimum amount of combined fluorine in the form of a fluoride.

Welding sleeve of thermoplastic material.

Abstract: The welding sleeve used for connecting pipes (1, 2) of thermoplastic material comprises a body (3) provided on its inner wall (14) of a winding drilling a wire resistor (10). The body (3) of the sleeve comprises a central portion (4) provided with grooves (8) in which is wound the yarn resistance (10). Projections at the bottom of the grooves cause the formation of inflection points in the turns of the coil. The central part (4) is surrounded by an outer part (5). During welding of the sleeve, the turns (12) is elongate and, in the absence of these inflection points (16), they would separate from the inner wall. Through these inflection points (16) the wire resistance (10) is deformed only for such places and turns keep their position. For manufacturing a sleeve body into a piece the yarn is wound a resistance of a molded part provided with projections, on which the body (3) of the sleeve and wherein the body is injection molded (3) is removed after cooling.

Method of resistance welding

Abstract: An improved method for resistance welding two metallic articles, made of dissimilar metals which form brittle intermetallic compounds when melted together A first one of the metallic articles is provided with a tapered, flat-topped projection which is pressed against the other metallic article The first article preferably is composed of the metal most difficult to melt, as determined by the four parameters of melting point, electrical resistance, heat conductivity and specific heat The projection is formed with a predetermined relation between height, top width, and angle of taper such that a preselected extremely high welding current passed for a very short time will establish a maximum temperature near the top of the projection sufficient to melt the contacting surfaces of the two metallic articles and a temperature gradient such that an intermediate portion of the projection becomes markedly plastic while the adjacent base portion of the projection remains undeformable under extremely high welding pressure Impurities and intermetallic compounds in the molten metal at the top of the projection are squeezed out to the periphery of the surfaces to be welded, and the weld joint is made between plastic but unmelted metal of the projection and the other article