Showing papers on "Butt welding published in 1975"

Analysis of Thermal Stresses and Metal Movement During Welding—Part I: Analytical Study

Abstract: This is the first part of a study of thermal stresses and metal movement during welding. This part discusses analysis of two-dimensional thermal stresses and metal movement during bead-on-plate and butt welding. A finite-element formulation has been derived, based on the variational principle. The formulation includes temperature dependence of material properties as well as the yield criterion.

Analysis of Thermal Stresses and Metal Movement During Welding—Part II: Comparison of Experimental Data and Analytical Results

Abstract: This is the second part of a study of thermal stresses and metal movement during welding. Part I described the finite-element analysis of two-dimensional thermal stresses and metal movement during bead-on-plate and butt welding. Part II presents results of experiments on bead-on-plate and butt welds in 6061-T6 aluminum alloy. Measurements were made of changes of temperature, thermal strains, and metal movement during welding. The paper then compares experimental data with analytical results. Good agreements were obtained between experimental and analytical results.

Butt-welding device

Abstract: A butt welding device wherein the trailing edge of a first or preceding strip and the leading edge of a second or succeeding strip are clamped in position, simultaneously cut off, and joined together by flash butt welding and thereafter the flash and upset are removed by machining.

Device for removing flash after resistance butt welding of rails

Abstract: A device for removing flash from rails after resistance butt welding, mounted on a welding machine case and split along the vertical axis of the rail, comprising three cutters embracing the rail along the entire cross-sectional perimeter thereof and coupled with a hydraulic cylinder drive, one of said cutters is pivotally mounted on said case, split along the vertical axis thereof and contacts the rail rolling surface, while the two side cutters which embrace the sides of the rail head, the web and the base flange of the rail are arranged symmetrically relative to the vertical axis of the case and hinged thereto, the top portions of said side cutters being linked by an articulated rod.

Butt welding process and apparatus for effecting same

Abstract: Disclosure is made of a butt welding process, whereby butt ends of articles to be welded together are placed one opposite the other in a chamber containing a shielding medium. The butt ends are then heated until a layer of molten metal is formed on their surfaces, and upset in order to effect their plastic deformation and produce a weld joint. According to the invention, the heating and flashing-off of the butt ends are effected by a low-pressure arc uniformly distributed over the entire butt end surfaces of the articles being welded. The proposed method is effected through the use of an apparatus which, apart from a welding transformer whose secondary winding terminals are connected to articles being welded, comprises, in accordance with the invention, an auxiliary transformer that serves to initiate a low-pressure arc, or, successively, a glow discharge and a low-pressure arc between the butt ends of the articles being welded, as well as to stabilize said low-pressure arc, the secondary winding terminals of the auxiliary transformer being connected to the articles being welded via a valve-type breaker intended for controlling the low-pressure arc. The proposed process and apparatus for effecting this process make it possible to weld articles with different cross-sectional configurations, while making use of small deformations of articles in order to produce a weld joint. The process and apparatus of the present invention also account for a stable welding process.

Method and apparatus for controlling flashing speed during resistance butt welding

Abstract: A method for controlling flashing speed during resistance butt welding comprises measuring values of current density for at least two joints between parts being welded, converting them into d-c. voltages, detecting a maximum voltage value, comparing it to a preset d-c. voltage, the resultant difference value being used as flashing speed control parameter. An apparatus for carrying out the method comprises electric circuits whose number is equal to the number of joints being welded. Each circuit comprises a welding transformer and a circuit for conversion of flashing current density into d-c. voltage. A maximum signal detector comprises circuits for conversion of current density into d-c. voltages, whose number is equal to the number of joints being welded. The detector output is connected to the circuit for comparing a current voltage value to the preset one. The apparatus according to the invention may be used mainly for controlling flashing speed during concurrent resistance butt welding of several joints of large and different respective cross-sectional areas.

Machine for the resistance butt welding of pipes by fusion

Abstract: The machine disclosed is provided with a manipulator which aligns and moves pipes in course of welding and incorporates a hollow rod for the movement of the manipulator relatively to the pipe joints. The rod is immovably attached to the body of the manipulator and is provided with a partition subdividing the rod bore into two spaces. One of the spaces is intended to be filled with a working fluid and the other accommodates on the partition a hydraulic system for feeding and controlling both actuators of pipeholding clamps and a means for moving the pipes in the course of welding, the means comprising hydraulic cylinders whose bodies are immovably attached to the body of a movable aligning unit between hydraulic cylinders which are mounted on the unit to actuate the clamps holding fast one of the pipes being welded whereas piston rods of the hydraulic cylinders that move the pipes are immovably attached to the body of the manipulator insulated electrically from an immovable aligning unit. It is expedient to use the machine disclosed for welding bigbore pipes into a continuous pipeline. The layout of said machine provides for quick withdrawal and replacement of hydraulic actuating cylinders without taking apart the welding manipulator. This feature adds to the number of purposes the machine can serve, promotes its serviceability and repairability.

Method of non-destructively testing aluminum-to-copper welds

Abstract: Discloses a method of non-destructively testing an aluminum-to-copper butt weld in a bar comprising an aluminum section and a copper section joined together by said weld. Forces are applied to the bar in such a manner that the weld is subjected to total stresses that are at least 80 percent, and preferably at least 90 percent, shear stresses. An acoustic emission signal is produced by the stresses at the weld, and this signal is sensed by a suitable transducer to provide an indication of weld quality.

Process for obtaining skeins of wire rod of a weight which is a multiple of that of a wirebar

Abstract: A process for obtaining skeins of wire rod of indefinite length comprising butt welding under axial pressure two successive wirebars already rough shaped and having their ends cropped with shears or another device, and then hot rolling until the final required wire rod size is obtained.

Heat exchanger construction with butt welded end plates - uses expansion joint on outer casing and temporary tube elongation

Abstract: The assembly method allows the use of both end plates with holes of the same dia. as the bore of the pipes and using butt welding exclusively. Pipes, stretcher and holding rods are first fitted and welded to one end plate. The outer cylinder is then fitted and the expansion joint is opened by several millimetres. The second end plate is positioned on the cylinder. Plugs are fitted into the tube ends and the tubes are filled with inert gas after centering rods are placed. The rods incorporate mechanical or thermal units which cause an elongation of the pipes until they touch the seatings in the second end plate. These ends are now butt welded and after removal of the tools the expansion joint is contracted.

External tool welding bead for formation prevention - in butt welding of plastics profiles with undercuts

Abstract: The external tool comprises >=2 separable parts which when moved close together, snugly surround the profile. Near the undercuts (which are hollowed out perpendicularly to the direction of sepn) an element is provided which fits into, and fills, the undercut and which is retractable at the start of the sepn. movement but is extended when the separable parts are brought together again. The elements are pivotably placed, before the start of the sepn. movement, at right angles to the sepn. direction or on a circular arc which runs at right angles to the sepn. movement. The elements may be pivoted from the undercut by means of a special adjusting dev ice, and/or swung back again.

Prevention of end cracking in one-side automatic welding

Abstract: Recently one-side automatic welding has widely prevailed in the assembly stage of Japanese shipyards. As one of the problems of welding procedure, as well as any other welding technique, cracking which sometimes occurs near the end of weld has become an important problem. As regards the prevention of end cracking in one-side automatic welding, a new preventing method is proposed. In the process of welding hydraulic jack should be used to control the opening displacement of the plates at the end of weld and furthermore specimen should be used with no bead placed extended over 2000mm from the specimen end. Experimentally it is comfirmed that end cracking could be prevented almost perfectly where the new preventing method is applied. In order to analyze this preventing method the authors have proposed a new calculation technique in the seam welding. The most significant feature of this technique differing from ordinary welding thermal stress analysis is that the conditions of calculation are simulated to be those of more realistic welding procedures. The following assumptions are imposed in order to calculate stress and strain during welding. 1) Before welding, two plates are connected with only tack welds and welding groove is free edge. 2) Stresses are always assumed to be elastic except in metal beyond 700 deg C in which stiffness is taken as zero, so molten pool near the arc is free from stress. 3) When the arc reaches to a tack weld, the tack weld is melted away and redistribution of the forces takes place. 4) As the arc proceeds, the temperature of deposit metal decreases at a certain portion, then melted metal is solidified and the metal at the portion now becomes stiff, so the portion should be changed to supported edge from free grooved edge beforehand. This calculation method is carried out by using the finite element method and it proves to be very effective for a time-depending welding phenomena. The following results are obtained. 1) End cracking in one-side automatic welding is greatly influenced by the displacement and its rate to which weld metal is subjected. 2) Cracking can be completely prevented by use of dynamical method whereby the end is externally restrained by a hydraulic jack and in addition by the method improving the bead shape and increasing hot ductibility of weld metal by using of multiple electrodes welding process. 3) To analyze transient phenomena in one layered butt joint welding, a new numerical calculation technique by using the finite element method is proposed. This method proves to be very effective for such a time-depending welding phenomena. 4) It is comfirmed that the posibility of occurrence of end cracking in 20Y specimen seems to be seldom, according to the calculated results by using this numerical method. 5) When weld length is about 6,000mm, changes in groove opening caused by the welding heat source are almost the same as those for welding actually done in shops.

Universal welding set for alternating or direct current - suitable for plasma-arc or tungsten-inert gas welding

Abstract: A power-supply unit with transformer and rectifier, plus controls for the current, inert-gas and coolant, has switches used to isolate the D.C. supply and switch in a second, continuously-adjustable, A.C. transformer which is pref. housed in a separate box. The advantage is that a D.C. welding set can be rapidly converted for use with a.C. by means of simple switches and the typa of A.C. transformer readily available in most workshops, so that the inert-gas and coolant controls on the D.C. set can be used in A.C. welding.

Resistance butt welding machine for chain links - with automatic switch off if link mal-alignment occurs

Abstract: The parent patent described a machine for the resistance butt welding of joined, C-shaped chain links, using a saddle for the link being welded and supports for the two adjoining links, plus an upsetting device for squeezing the two joint surface of the link being welded together, the squeezing device being actuated by a curved disc on a control shaft used in conjunction with a double-armed lever. In the present invention, the curved disc used for power operation of the double-arm lever is a cam in contact with a roller mounted on one arm of the lever and the piston of a pneumatic cylinder is attached to the other arm of the lever and presses it towars a limit switch. If the link being welded is mal-aligned, the limit switch operates a warning signal and/or switches off the machine to prevent damage.

Well casing butt welding clamp - with jaws on hollow rod cones for insertion inside casing bore

Abstract: A lifting and lowering clamp for the string of a well casing for butt-welding operations of one length to another consists of two coaxial systems which are both inserted inside the casing. The butt welding machine at the wellhead has housings which surround the casing and need not be shifted as casing and clamp can pass through their bore. The butt welding machine need not be moved which increases the productivity. A machine without split housings produces a better quality of weld.

Tube mfr by seam welding formed strip - using induction coil for pre-heating, to increase the welding speed

Abstract: In butt welding the edges of slit tubes in tube mfr. by longitudinal or spiral seam welding, the pre-formed tube travels continuously at a prescribed speed through an aligning device which closes the gap between the longitudinal edges prior to welding, and an induction heater is located ahead of the welding unit for pre-heating the gap. A ring-shaped induction coil is located round the slit tube, ahead of the aligning device, for generating an alternating field along the tube axis, and an electrical insulator is used to hold the two edges apart until they reach the aligning device. The leads carrying the current to the induction coil do not run along the seam so that inconsistent pre-heating does not occur.