Showing papers on "Welding published in 1977"

Heat treating and melting material with a scanning laser or electron beam

Abstract: A thermal analysis for laser heating and melting materials is derived for a Gaussian source moving at a constant velocity. The resulting temperature distribution, cooling rate distribution, and depth of melting are related to the laser spot size, velocity, and power level. As the power is increased to heat the liquid above the boiling point, a transition to deep penetration welding is described. Calculations are presented for 304‐stainless steel which are in agreement with experiment.

The Ultrasonic Welding Mechanism as Applied to Aluminum-and Gold-Wire Bonding in Microelectronics

Abstract: This paper represents a review as well as an extension of previous work concerned with the mechanism of microelectronic ultrasonic welding for both aluminum and gold wires. A series of experiments was carried out to determine the mechanism of gold-to-gold ultrasonic bonding. These experiments, including lift-off pattern studies, clamped-wire studies, and bond deformation versus ultrasonic vibration amplitude studies, indicate that gold ultrasonic bonding takes place primarily by means of a deformation mechanism as opposed to a heating or sliding mechanism. This is substantially the same result previously obtained from studies on the aluminum ultrasonic bonding mechanism. Further, it is shown that a deformation mechanism also holds for other forms of solid phase microelectronic bonding. Specific examples are taken from electric discharge "tweezer welds" and from thermocompression bonds. The role of contaminant removal and certain reliability aspects of ultrasonic bonding are also discussed.

Car body welding assembly system

Abstract: A body assembly system for welding different stamped sheet metal vehicle bodies at successive framing and finish welding stations including means for accurately locating different underbody, side and top components in required accurate geometric relation at a framing station with programmable welding means for producing different initial retention welds at the framing station as well as finishing welds at successive "respot" welding stations as required for the different bodies. The system includes means for rapidly positioning locating tooling for body components at the framing station as required for different bodies as well as means to minimize and facilitate change of special tooling for model changeover.

Device for teaching and evaluating a person's skill as a welder

Abstract: An apparatus for simulating an arc welding operation, for training welders and for evaluating a welder's performance including a target representing a simulated weld to be made, mechanism for imparting predetermined motion to the target, a simulated welding tool including a simulated welding rod and a holder for the rod, the rod having a free end with an element adjacent thereto having properties capable of being sensed magnetically, a magnetic sensor assembly located adjacent to the target for movement therewith and including members capable of responding to the presence of the magnetic field produced by the magnetic element on the rod for producing responses depending upon the position of the simulated welding rod relative thereto and the distance of the rod therefrom, the magnetic sensor assembly including angularly related pairs of opposed sensor members arranged to produce responses to represent the position of the simulated welding rod relative thereto in two different angularly related directions, each of the sensor members being capable of producing a response when in the field of the magnetic element, an electric circuit connected to the sensor members of the aforesaid pairs including circuitry for combining the responses produced by selected ones of the sensor members to produce electric signals representative of the position of the free end of the rod relative to the sensor members and representative of the distance between the rod and the sensor assembly, and a sensor element located on the rod holder, the sensor element being constructed and positioned to respond to the angular orientation of the simulated welding rod relative to the target. The present apparatus also includes an electric circuit for producing audible responses and/or visual indications to simulate an arcing condition and to indicate and record errors that an operator makes in following the target during a simulated welding operation.

Welding simulator spot designator system

Abstract: A source of light is located within the movable target of the welding simulator. The electrode holder mounts a welding rod with a reflective surface. Light from the light source is reflected by the reflective surface onto a spot designator surface. The spot designator surface is white so that the light is re-reflected as a spot to provide a visual cue as to the proper spacial relationship between the welding rod and target.

Mutagenicity of fume particles from stainless steel welding.

Abstract: Welding fume particles collected from different welding procedures were tested for mutagenicity in Escherichia coli, with the inhibition zone in pol A- as compared to pol A+, and in Salmonella typhimurium, TA 100 strain. While no mutagenicity was found with mild steel welding, a mutagenic effect was established with samples from stainless steel welding. This mutagenicity was particularly associated with manual metal arc (MMA) welding, and less so with metal inert-gas welding. A decrease in or an elimination of the effect occurred with a liver microsomal metabolizing system (S-9 mix). The MMA samples produced the strongest mutagenic effect. More-detailed investigations on these samples showed that the mutagenic agent(s) is water soluble. An increased mutagenicity, which also revealed the induction of frame shift mutations, was found with TA 98. The same welding fume sample was used for a mutagenicity test (resistance to 6-thioguanine) with V 79 hamster cells. Because of the high toxicity of these welding fume particles on the cells, only very low concentrations could be tested, but the increase of mutations, when compared to the negative control, was significant. It is suggested that hexavalent chromium may be involved in the mutagenic effect of the welding fumes.

Method of applying printed labels to flexible envelopes using corona discharge treatment

Abstract: Plastics bags are formed by welding a continuous tube or a pair of continuous films or a continuous folded film, and the finished bags are marked by attachment of pre-printed panels of plastics material using adhesion by corona-discharge irradiation of both the bag material and the printed panel material.

Urinary chromium as an indicator of the exposure of welders to chromium.

Abstract: Five welders working with high alloy Cr-Ni steel and one working with mild steel were followed during one work week. The chromium concentration in air was measured concomitantly with urinary chromium determinations. The water-soluble chromium concentrations in air exceeded 0.05 mg/m3 during welding with coated electrodes, but metal inert-gas (MIG) welding produced much lower concentrations. The proportion of water-soluble hexavalent chromium in the air was usually more than 50% of the total chromium concentration during welding with coated electrodes, whereas less than 10% of the chromium produced during MIG welding was in a water-soluble. Since water-soluble chromium (hexavalent) is the more important biologically, the determination of both water-soluble and water-insoluble chromium concentrations is emphasized instead of the measurement of the total concentration. The urinary chromium concentration proved to be a good indicator of short-term exposure to water-soluble chromium when exposure was above the current threshold limit value of 0.05 mg/m3, concentrations of more than 30 microgram/g of creatinine representing an exposure level higher than the threshold limit value.

Processes and materials of manufacture

Abstract: 1. The Manufacturing Engineer. 2. Classification and Fabricating Characteristics of Metal and Composites. 3. Numerical Control (NC) and Computer Steps to the Automated Factory. 4. Metrology and Quality Control. 5. Metal Cutting Theory and Practice. 6. Turning and Related Operations. 7. Holemaking and Related Operations. 8. Milling, Broaching, and Sawing. 9. Grinding and Related Abrasive-Finishing Processes. 10. Metal Casting Processes. 11. Plastics and Adhesives. 12. Power Metallurgy. 13. Metal Stamping and Forming. 14. Bulk Deformation of Metals. 15. Welding Principles and Arc Welding. 16. Gas Welding, Brazing, Cutting Systems, and Weld Testing. 17. Resistance, Specialized, and Solid State Welding. 18. Non Traditional Machining. 19. Process Planning.

Comparative Distortion in Three-Unit Fixed Prostheses Joined by Laser Welding, Conventional Soldering, or Casting in One Piece

Abstract: This study was conducted to evaluate objectively the relative distortion in three-unit bridges joined by laser welding, soldering, or one-piece casting techniques, Each procedure was replicated five times. Laser welding and one-piece castings of three units were found to be significantly superior to soldering. The laser welding was most reliable.

Laser beam welding

Abstract: Laser beam welding apparatus comprising a body with a passage through which the laser beam is directed and focused to a position outside the body closely adjacent to a terminal portion of the passage. A second passage opens into the first to direct a transverse jet of shielding gas to sweep away the plasma formed during welding through an aperture in the opposite wall of the first passage. Since the welding zone is virtually enclosed by the body the incidence of air entrainment by the transverse jet of shielding gas is minimized.

Method of coupling plastic pipes by welding and a connection piece for coupling same

Abstract: The coupling of two tubular elements is achieved by welding them together by energization of an electrical resistance element, the one element comprising a male end, the other a socket end. The coupling operation is carried out by means of a composite connecting piece comprising two rings which are fitted on one another, one acting as a support for a bifilar electrical resistance element and the other as a sheath. The electrical resistance element is thus uniformly coated in plastic material and is accurately centered, thereby ensuring uniform heating and welding. This coupling method is for use in coupling discharge pipelines for waste water and rain water and for conduits for industrial fluids.

Method for controlling an automatic pipe welder

Abstract: Method for controlling an automatic pipe welder is disclosed. In the automatic welder which requires remote control, welding conditions for butt welding pipes are stored and an actual joint geometry or groove shape is sensed. From signals relating to the stored welding conditions and the sensed groove shape, a control command signal in actual welding is produced to effect welding under an optimum condition. On the other hand, an arc condition at an actual welding point and a melting condition of a metal are monitored and displayed to modify the welding conditions in accordance with the monitored condition to control the automatic pipe welder.

Welding Process Technology

Abstract: Preface 1. Properties and classification of welding processes 2. The welding arc 3. Flux-shielded arc welding 4. Gas-shielded arc welding 5. Unshielded and short-time arc welding 6. Resistance welding 7. Thermochemical welding 8. Radiant-energy welding 9. Solid-phase welding 10. The selection of welding processes 11. Automatic welding 12. Economic considerations Index.

Installation for surfacing using plasma-arc welding

Abstract: The invention relates to an installation for surfacing by plasma-arc welding including in particular a plasma torch and a control and power supply device for the formation of a transferred arc between the electrode of the torch and the workpiece to be surfaced and of a non-transferred arc between the said electrode and the nozzle of the torch, the control and power supply device comprising a single d.c. source one terminal of which is connected to the electrode of the torch and the other terminal of which is connected, on the one hand, to the workpiece to be surfaced and on the other hand to the nozzle of the torch via a resistance. The plasma torch has at least two cooling systems supplied by a distribution device which is controlled as a function of the cooling water temperature and/or the electrical power consumption of the torch.

Melting Phenomena in Solid State Welding Processes

Abstract: Different aluminum and copper alloys with a well defined microstructure are joined by ultra­ sonic, explosion and friction welding. Transmission electron microscopy is used to study the microstructure with­ in the bonding area of the welded joints. From the change in microstruc­ ture, as compared to the material in its original state, conclusions are drawn on the bonding mechanism of these welding processes. In ultrasonic welding, bonding occurs predominantly by a short time melting of a narrow surface layer (less than 1 fim thick) followed by rapid cooling. In explosion welding, melting phenomena are not only found in the well known melt pockets of wavy interfaces; even plane interfaces of similar alloy welds show evidence of melting within a 0.5 to 4 /am thick zone. During the friction welding of two dissimilar aluminum alloys used in this investigation, the temperature exceeds the melting point only within isolated areas along the interface up to 15 fim in size.

Process and apparatus for monitoring the quality of weld spots produced by resistance spot welding

Abstract: The invention relates to a method and apparatus for monitoring the quality of weld spots produced by resistance spot welding according to which a weld spot which has just been made is observed by means of a video camera sensitive to infrared radiation at a well determined instant of its cooling, with a view to comparing it with a reference weld spot observed previously under the same conditions; the value and passage of the welding current is controlled by means of the video signal and the synchronization signals coming from said camera, which signals are exploited to make an image reconnaissance by counting scanning lines or dots defined along the lines by a clock, when this video signal becomes greater than an electrical voltage representative of the level of emission of infrared radiation of the periphery of the reference weld spot.

Method of and device for plasma MIG welding

Abstract: Plasma-MIG welding involving the use of two parallel consumable electrodes axially introduced into a plasma arc initiated by a non-consumable electrode and out through a nozzle. All three electrodes are maintained at a positive polarity whereby a substantial increase of the deposition rate is achieved, without rotation of the MIG-arcs and without exceeding the critical current intensity.

Ultrasonic welding of thermoplastic fabrics

Abstract: Method and apparatus for patching or seaming thermoplastic mesh fabrics, such as used in the papermaking industry by means of an ultrasonic welding tool. The tool is provided with one or more tips having raised surface portions or projections adapted for contacting the plastic mesh at a plurality of spaced points whereby ultrasonic welding is accomplished without substantial disruption or dimunition of the generally uniform porosity inherent to the mesh fabric. The method modifications involve the use of templates for guiding the positioning and movement of the ultrasonic welding tips for both butt seaming and overlap seaming of the opposed edges of thermoplastic mesh fabric. In the butt seaming technique, the outermost weft filaments of the opposed edges of the plastic fabric are replaced by one heat stabilized filament and the picket ends of the fabric are interdigitated about this stable filament preparatory to the welding step.

Two-layer surfacing process by fusion welding

Abstract: A fushion welded surfacing process for use with crack prone substrates is described The process involves the application of an intermediate layer of crack resistant alloy by fusion welding followed by the application of the desired final surfacing alloy by fusion welding The intermediate layer is an age hardenable nickel superalloy to which intentional additions of manganese have been made The final surfacing alloy may be of the hardfacing type or may be of a type which imparts corrosion and oxidation resistance to the underlying article

Mounting for ceramic turbine rotor on metal shaft - uses shrink or friction fit or friction welding at end faces

Abstract: The mounting for a ceramic rotor (1) esp. a turbine wheel on a metallic shaft (2) comprises a frictional connection, formed by making the rotor a shrink fit on the shaft. Alternatively the shaft and the rotor may be pressed together axially by a screw through both. The rotor could instead be welded or soldered to the shaft. Welding is esp. by friction welding at the end faces of the two components. Diffusion welding may be used at other conical surfaces. The shaft may be a molybdenum-titanium alloy.

Flux cored wire for welding Ni-Cr-Fe alloys

Abstract: A self-shielding, flux cored arc welding electrode for joining Ni-Cr-Fe alloys and overlaying dissimilar metals. The wire has a nickel-chromium containing alloy sheath and a flux core containing special proportions of carbonates, fluorides, metal oxides, and powdered metals. Sound welds can be prepared without the use of a supplemental inert shielding gas. Welded joints provide essentially the same properties as those of the Ni-Cr-Fe base alloy.

Automatic pipe welding apparatus and method

Abstract: A TIG pipe welding method which employs two sets of machine guide surfaces on the pipe ends. First radially inner guide surfaces cooperate with a sensor coupled to the welding torch to continuously monitor the arc gap between the welding electrode and the weld puddle as the welding electrode moves around the circumference of the pipe. The second set of radially outer surfaces cooperate with a welding carriage to guide the carriage and welding modules around the pipe joint. The carriage is constructed to provide a sealed welding chamber surrounding the electrode. An additional flow of shielding gas is provided around the torch electrode of a TIG or hot wire TIG welding module to augment the normal gas shield. The augmented shield provides a gas flow in opposition to pressurized air flowing through the welding chamber to prevent exposure of the weld nugget to the pressurized air flow being maintained in the welding chamber while permitting the pressure forces to be transmitted through this shield to the weld nugget, creating a "puddle pushing" effect. The transfer of forces through the gas shield, while preventing contaminating air from entering the weld zone itself, provides a positive force for pushing the molten weld puddle through the joint to the interior surfaces of the joined pipe ends. The pressurized air further flows outwardly between the seals of the welding carriage and the pipe surfaces to create an air cushion between the pipes and the carriage. An internal weld backup and pipe alignment ring is also provided.

Remote control portable wirefeed arc welding system

Abstract: A remote control unit for closing a normally open contactor in response to closing of a normally open gun switch in a portable wirefeed arc welding system having a power source including the contactor, a portable wirefeed unit, a welding gun, a ground cable interconnecting the power source and the work, an electrode power cable interconnecting the power source and the wirefeed unit and gun, and control leads interconnecting the wirefeed unit with the work and the gun; wherein a capacitor in the control unit is operable to place an override current on the ground and electrode power cables in response to closing of the gun switch, and sensing means comprising a sense relay are operable in response to such override current to effect closing of a normally open cycle hold delay relay and the contactor. The cycle hold delay relay, in turn, closes a fourth or rearming delay relay which opens the circuit to the sense relay. So long as welding current is drawn, the first control relay remains closed to hold the cycle hold delay relay closed. An interruption of welding current for two seconds causes the cycle hold delay relay to time out to open the rearming delay relay and the contactor.

Welding shield and plasma suppressor apparatus

Abstract: A welding device capable of providing a blanket of nonreactive gas to isolate atmospheric gases from a weld zone to prevent weld contamination and capable of providing a stream of suppression gas across the path of a welding beam to suppress the formation of a beam absorbing plasma is disclosed. The device comprises a housing having a welding beam entrance port, a structure wall cooperating with the housing to form a first cavity therein and having an exit port aligned with the entrance port, means for supplying suppression gas to the first cavity, means for exhausting the suppression gas from the first cavity, a base cooperating with the housing and the structure wall to form a second cavity within the housing, means for providing a nonreactive gas to the second cavity, and means for passing the nonreactive gas from the second cavity to the weld zone.

Effects of residual stresses on the ductile strength of plane welded grillages and of ring stiffened cylinders

Abstract: Structural engineers have for a long time accepted the importance of residual stresses when considering fracture modes of failure. It is only in the last quarter-century that attention has been focused on their adverse effect on ductile modes of failure and, in particular, on buckling collapse. The last decade has seen increased research activity, spurred on by recent failures in box-girder bridges.The nature and distributions of locked-in-stresses during hot and cold forming and during welding are outlined. The effect these have on inelastic buckling collapse of flat plated grillages and ring-stiffened cylinders is examined for all likely modes of failure. Experimental data are scarce, but they confirm that both forming and welding stresses can reduce the stiffness and strength of both types of structure very significantly. This is caused by a direct reduction in buckling stresses (as usually supposed), but equally important is the loss in stiffness due to early yield and other effects. In partic...

Apparatus for welding pipes

Abstract: A welding apparatus for pipes which provides for a guide means which is to be fixedly secured to the pipe adjacent the welding area, a first carriage and a second carriage is movably supported upon the guide means with each of the carriages supporting a pair of spaced apart welding heads. Attached to the guide means is a driving chain. Mounted on each of the carriages are motor means which, in turn, operate through the driving chain to move the carriages in a prescribed manner with respect to the guide means. The welding heads of each of the carriages move within the same plane but each are movable in a separate one hundred and eighty degree arc thereby forming a continuous circle. Associated with each welding head is a weld groove tracking system which automatically maintains each welding head correctly aligned within the welding groove. The entire apparatus of this invention, when combined with appropriate electronic computer equipment, automatically welds an adjoined pair of piping sections.

Ultrasonic paper welding

Abstract: This invention provides a method and aparatus for welding together paper sheets, more especially for, but not limited to, bookbinding. The sheets are held in a desired relation with one another, and the portions to be connected are held together while subject to ultrasonic vibration which fuses ingredients of the paper so as to weld the fused areas together. A folded sheet can be welded across a midportion thereof and then folded along the weld or parallel to the weld to make a signature for a book; or stacked sheets can be bound together along their rearward edge portions by the ultrasonic vibrations.

Control apparatus for an automatic pipe welder

Abstract: Disclosed is a control apparatus for an automatic pipe welder, for controlling the automatic pipe welder which continuously butt welds pipes while it is running along a welding line on the periphery of a pipe, in accordance with predetermined welding conditions for each of a plurality of welding areas sectioned along the welding line. All of the welding conditions for the welding areas are stored in a digital storage device while welding conditions on an area currently being welded are stored in another storage device. The contents of the second-mentioned digital storage device are converted by a digital-analog converter to analog signals, which are then held respectively in corresponding sample and hold circuits. Outputs of the sample and hold circuits are supplied as control commands to respective control units which control the welder in accordance with the welding conditions. In this manner, the construction of the control apparatus and a control panel thereof is simplified.

Beam welding apparatus and method

Abstract: An apparatus and method are provided for welding portions of members disposed in edgewise abutment or overlapping relationship by means of a high intensity beam of radiation such as a laser beam or an electron beam generated by an electron gun. In one form, the two members are sheets of weldable material such as metal or plastic which are driven between aligned rolls or wheels into edgewise or overlapping abutment while one or more beams of radiations intersect either or both the members immediately in advance of or adjacent to the rolls or wheels. The combined effects of the force applied by the wheels and the heat of the beam serve to provide portions of the members welded together.