Showing papers on "Butt welding published in 1976"

Review of the present state-of-the-art in explosive welding

Abstract: A brief review of the history and simplified mechanism of explosive welding is presented. Consideration is then given to the present state of understanding of the parameters which control the explosive-welding process, and the implications of these parameters in relation to thin- and thick-plate cladding. The problem of cladding large thick plate is then considered and experimental data are reported which support the welding parameters proposed, and which allow definite conclusions to be drawn of the set-up required to achieve welding over the whole plate and close to the edges of the parent plate. Applications of explosive welding to cylindrical surfaces are reported including tube-to-tube welding, plugging of heat exchangers, welding of collars to tubes, etc. In particular, the problem of ligament distortion in tube-to-tubeplate welding and plugging is considered. The alternative possibility of placing bungs in the holes adjoining that in which a tube is being welded is examined. Other applicati...

A major advance in high-power electron-beam welding in air

Abstract: A major extension of the capabilities of nonvacuum electron‐beam welding follows from the development of a machine with higher beam power. Tests with a new atmospheric electron gun operating at 60 kW have shown that the advantages of nonvacuum electron‐beam welding must be reevaluated. Gas heating produced by the beam itself becomes very pronounced, so that electron scattering is reduced causing the high‐power density of the beam to be retained over larger working distances. Single‐pass butt welds with a depth‐to‐width ratio of 4 : 1 can be made in 3.8‐cm‐thick steel at a speed of 0.77 cm/sec, while the ultimate welding depth exceeds 5 cm. Medium thick material, e.g., 1.3‐cm steel, can be welded at a 5‐cm work distance, with a depth‐to‐width ratio of 3 : 1. The large work distance permits access to more complex structures and interior corners such at T sections, which can now be fabricated from a plate, 1.3 cm thick, at a speed of 2–3 cm/sec, making a full through weld from one side. Also, seam welds of two 3‐mm‐thick hot‐rolled steel sheets can be produced at speeds of up to 15 cm/sec. High‐power machines need not be significantly larger or costlier than low‐power guns, and the present 60 kW does not represent any technical limit. Welding efficiency improves with higher power; when welding steel of 2 cm thickness or more the energy efficiency of the process at 60 kW is better than 50%, while at 40 kW it is merely 30%. In addition, the high power permits greater welding speed. These developments translate directly into improved cost justification for electron‐beam welding and a broad expansion of its possible applications.

Finite - element analyses of some joints with the welds transverse to the direction of stress

Abstract: It is know that the geometrical shape of welded joints leads to the formation of stress concentrations both at the weld toe and, in the case of load-carrying fillet welds, at the weld root. The result is that fatigue cracks are liable to form in service. The rate of growth of a fatigue crack can be related to the range of stress-intensity factor at the crack tip. Since it is not known to what extent the stress concentration act on the propagating crack, it is difficult to carry out a crack-propagation anaysis for a welded joint or to assess the influence of a defect from the point of view of brittle fracture. The Author describes some finite-element analyses that have been carried out. Three main types of joint have been studied, namely transverse non-load-carrying fillet welds, transverse load-carrying fillet welds, and K butt welds. In addition, in the case of the non-load-carrying fillet welds the influence of biaxial, as opposed to uniaxial, loading has been investigated. For comparative purposes, a limited investigation was also made of the influence of weld shape in transverse butt welds.

Welding of aluminum and magnesium alloys

Abstract: This invention generally relates to a method for butt welding high strength aluminum and magnesium alloys. More particularly this invention pertains to a novel technique for welding (a) high strength aluminum alloys to each other, (b) high strength magnesium alloys to each other, and (c) high strength aluminum alloys to high strength magnesium alloys, under a combination of controlled pressure, temperature and time conditions.

Experiences with haz cold cracking tests on a c-mn structural steel

Abstract: The heat-affected zone cold cracking tendency of a C-Mn structural steel was evaluated using controlled thermal severity (CTS) and Tekken Y-groove specimens. This permitted a comparison of the performance of the single-pass fillet weld test and the single-pass butt weld test and the development of improved understanding of the performance of the latter. No cracking occurred in the CTS tests, but severe weld or heat-affected zone cracking was encountered in the Y-groove tests under conditions which had been expected to be less likely to produce cracking than the conditions employed in the CTS tests. It was shown that special procedures are necessary in order to control the critical root opening in the Y-groove specimen. A preferred method is to employ a two-piece specimen which has wide root faces in the restraint portions. When these faces are in contact, the correct root opening is maintained in the test weld portion after welding the restraint portions.

Prevention of hot cracking of butt welds in steel panels by controlled additional heating of the panels

Abstract: A procedure is presented for controlled additional heating during and after welding in modern panel production lines prefabricating hull and bottom sections, the object being to prevent end cracking. The search for the optimal distribution and minimal amount of thermal energy needed for the additional heating is formulated as a mathematical programming problem. Two-sided irradiation is suggested as a feasible way of transmitting the thermal energy into the panel. A case for application in a Swedish panel production line is studied, and a formula for calculating the required additional heating is suggested. A preliminary study indicated that suitable controlled additional heating might possibly generate additional thermal stresses which might neutralise the existing crack-inducing thermal tensile stresses across the welded joint. The paper describes the systematic search for the distribution of additional heating over the plates of the panel such that the detrimental tensile stresses would be eliminated and at the same time the additional thermal energy supplied to the plates would be kept as small as possible.

Thermocompression welding device

Abstract: A thermocompression welding device including a welding head having two tools for automatically and simultaneously effecting welds between a connecting wire and a pair of contact areas, one on a semiconductor chip and one on a housing for the chip. The weld head is transversed between consecutive weld positions using an X-Y table. The apparatus provides automatic adjustment of connecting wire length, and matched automatic adjustment of weld head separation, corresponding to different contact area spacings and automatic orientation of the welding head to correspond to different orientations of the pairs of contact areas. Preprogrammed lengths of wire are fed to the welding head from a continuous coil and bent into position for simultaneous engagement by both welding tools, the wire being severed adjacent one of the welds immediately following each welding operation.

Arc time indicating apparatus for stud welding utilizing a capacitive power source

Abstract: Apparatus is provided for measuring and indicating the length of time a welding arc exists in a stud welding cycle utilizing a capacitive power source. Heretofore, the arc time of stud welding apparatus employing capacitors for the power source has only been measured in the laboratory with an oscilloscope. The new indicating and measuring apparatus for the arc time is usable with conventional stud welding, contact stud welding, and gap stud welding employing capacitive power sources. The apparatus produces a number on a visual indicator in the form of a meter or a digital read-out device and the operator can note the number when the ultimate weld is produced. The operator can then subsequently adjust the equipment to repeat that number on the indicator to always be assured of optimum weld quality without the necessity of repeating a number of test welds.

Inert gas butt welding of pipes - using inflatable balloons to form gas chamber inside pipes

Abstract: Auxiliary device for welding operations, esp. for butt welding of pipes using an inert gas or reforming gas to protect the weld, the novelty being that the device consists of two expandable sealing bodies, located in the pipes on each side of the joint leaving a distance so they are not unduly exposed to heat, and forming a chamber connected by pipes to a source of reforming gas and also to the open air. The bodies pref. consist of two inflatable balloons made e.g. of heat-resistant rubber and which can be filled with compressed air. Provides reliable protection of the weld from oxidn. without excessive and costly use of a protective gas.

Tensile properties of a514 steel butt joints containing cluster porosity

Abstract: The effects of cluster porosity on the tensile properties of A514 steel butt weldments were assessed. Cluster porosity was measured both in terms of the actual total area of pores and of the area of the cluster (including metal ligaments, or webs, that connect pores). Results showed that the tensile strength of the welded metal is not significantly reduced if the area of pores and the cluster area are below critical sizes; however, ductility is rapidly reduced until these sizes are reached. Consideration of the implications of tensile test data on both working stress design and limit stress design indicates that relaxation of welding codes may be considered for certain tensile loading applications if the codes are based on working stress design. This would be beneficial in terms of reduced project costs for weld rework. Relaxation of codes based on limit stress design should not be considered for the conditions of porosity covered in this study.

Stress concentrations in double welded partial joint penetration butt welds

Abstract: Results are presented for photoelastic analyses of stress concentrations in square butt welds that contain a centrally located unwelded area or discontinuity. The discontinuity may be intentional, as in a butt joint design that specifies a partial joint penetration weld, or it may be a defect such as inadequate joint penetration. Two kinds of loading are considered, namely, pure tension and pure bending. In pure tension the stress concentration based on mean plate stress is independent of the depth of the discontinuity when the depth is small and increases very rapidly for depths larger than one-fifth of the plate thickness. A basis is suggested for plotting fatigue test data which should reduce the scatter normally found in such tests. In pure bending the critical stress remains at the toe of the weld reinforcement for all but the largest discontinuities.

Butt welding plastics components in clamping frames - with adjustment both axially and perpendicularly to abutting faces

Abstract: A device for butt-welding plastics member comprises guide rails (6a,6b) which grip the members and are mounted on slides and are provided with end strips (7) which extend parallel to the butt surfaces, a heating blade being introduced between the plastics surfaces to melt them and then removed before they are brought together. The improvement resides in rails (6a,6b) being adjustable along their axes which coincide with those of the plastics members, whereas the end strips (7) are adjustable perpendicularly to the butt surfaces to be joined. Preferably, the longitudinal adjustment of the bars (6a,6b) is obtained by a tension screw (19) and two compression screws (17,18) at the ends remote from the joint. The end strips (7) are pref. adjusted by screws (12).

Apparatus for making seam welded tubing

Abstract: Apparatus for making seam welded tubing of the type comprising a first butt welding machine for joining together by submerged arc welding the adjacent ends of successive lengths of strip to form a continuous strip, a strip storing device for storing the continuous strip and a tube forming and welding machine is provided with a series of roll stands with the roll axes of successive stands offset from each other so that as the strip passes through the stands, it is turned over laterally. A second butt welding machine is then provided after the roll stands and before the strip is fed into the tube forming and welding machine so that the successive lengths of strip are first butt welded together along the joint on one face of the strip and then second welds are made on the other face of the strip so that no further welding is necessary after the tube has been formed and seam welded in the tube forming and welding machine.

Sliding-Seal Electron-Beam Welding.

Abstract: : A selected aerospace structure (f-14 wing beam) was successfully SSEB welded, thus demonstrating equipment capability to fabricate production parts. Tensile, fatigue and fracture toughness results are presented for a welded wing beam. Recommendations for further improvement or refinement of the SSEB welding equipment are included. A recommended industry equipment and a welding specification for aluminum, titanium and steel alloys are also included.

Device for holding two members in abutment for butt welding

Abstract: An apparatus or "coupler" for use in welding two lengths of pipe to be butt-welded, particularly suitable for welding a section of pipe to the end of a pipeline section being laid on the sea bottom, comprising an elongate body having a first portion and a second portion, which can be attached to respective pipes by means of respective attachment means and sliding means cooperating with the attachment means in order to move the first and second pipes towards each other, whereby, during the welding, not only the two pipes on internally changed to the said portions with their axes aligned, but are also drawn and held together, even when one of the pipes undergoes a longitudinal reciprocating movement.

High productivity one-sided mig-welding technique

Abstract: To overcome embrittlement problems associated with one-sided, submerged arc welding processes, the paper recommends the use of high current, one-sided MIG-welding with large diameter filler wires for the butt joints of ships' main hulls. The technique provides nearly the same productivity as that obtained by one-sided submerged-arc welding, and at the same time gives satisfactorily high levels of notch toughness at the weld fusion boundary as well as in the heat-affected zone. The paper indicates the recommended welding conditions for various services including the high strength D/E grades and low temperature service.

Electron-beam suction cup for linear welding large sheets

Abstract: The paper discusses the development of a special machine of the suction cup type, called the "Ventouse", which is capable of welding bulky parts without having to place them in a vacuum chamber. It describes the operating principle and the technology of the machine. Some laboratory examples of welding plates of steel and aluminium used in shipbuilding are presented. Results obtained in the laboratory show that the technology could be extrapolated to bigger machines which can be used for welding very large plates in shipbuilding.

Pipeline butt welding device - with seals forming chamber around butt joint filled with inert gas

Abstract: An auxiliary device for butt welding operations, esp. for pipelines, consists of two sealing elements which are introduced to both sides of an intended butt weld seam and form a sealed chamber around the weld. Inert gas is introduced to this chamber through a sealing element at one end and it escapes to atmosphere through a tube in the other element or through the butt joint. This prevents oxidn. and results in welds of higher quality without having to fill the complete pipeline with inert gas. The inert gas consumption is much less and it can be controlled for optimum weld quality.

Butt weld for flat plates - grinding wheel cuts groove along rear of initial weld

Abstract: A groove is cut along the back side of a butt held seam between two melting metal plates using a grinding disc which can be pivoted about a swivel pin and be moved along its axis of rotation. Mechanisms press the grinding disc against the weld seam so that while moving along the weld seam, the grinding disc grinds a groove (22) of regular cross section. The disc and the drive motor are arranged on a holder mounted on a slide carried by an arm, which has a slide guide and can pivot about the swivel pins. A support roller is tilted to a further lever arm which is pivoted to adjust the spacing between the grinding disc axis and the parallel support roller axis relative to the first arm.

Welding machine spacer plate with sensors

Abstract: A spacer plate construction for use in selective spacing between the head end and tail end of strips to be welded end-to-end by a welding machine. Sensors in the form of spring biased pivotal (or otherwise moveable) elements are mounted in longitudinally spaced cavities in the spacer plate to assure that the strip ends are held flush against the spacer plate before clamping for subsequent flash or butt welding. It is only when the sensor elements are moved inwardly to the sides of the spacer plate sufficiently to actuate a proximity switch mounted within the sensor plate that a circuit for initiating clamping of the head end and tail end of the strips can be initiated for subsequent welding.

Cold butt welding machine for aluminium and copper - has moving shears to clean joint-surfaces before welding

Abstract: Machine for cold butt welding semifinished metal products is fitted with a power-driven upsetting mechanism, guides, and two clamps for the parts being welded. The clamp housings are mounted on the guides so one housing is stationary while the other moves in the upsetting direction. Between the clamp housings are shear-knives with a vertical drive unit at 90 degree to the upsetting direction, for cleaning the joint-surfaces; and each clamp has two jaws and a separate drive unit. On the stationary clamp housing is a support which can move along the upsetting direction, the shears being mounted on this support, and the guides float in mountings on the upsetting mechanism, which is located on a pivot so it can move at 90 degrees to the axis of upsetting. Used for cold butt welding of Al to Al; Cu to Cu; and Al to Cu, e.g. the coil ends of large power transformers or for the mfr. of endless, i.e. very long, wires.