Showing papers on "Butt welding published in 1993"

Prediction of Residual Stresses in Butt Welded Plates Using Inherent Strains

Abstract: The source of residual stresses in the vicinity of a weld may be expressed in terms of inherent strains. The characteristics of the inherent strain distributions in butt welds are investigated. It is found that the patterns vary little with changes in the welding conditions and sizes of the welded plates. With some assumptions, simple formulas are derived for the distribution and magnitude of inherent strain in a butt weld. A method of predicting the residual stress in a butt-welded plate using the characteristics of inherent strain distributions is presented. The validity of the method is confirmed by thermal elasto-plastic analysis using the finite element method (FEM).

Method of butt-welding two plastic parts with an identifying code, using an automatically controlled electro-welding machine

Abstract: The invention is concerned with a method of butt-welding two plastic parts each equipped with an identifying code, using an automatically controlled electro-welding machine. A device for performing a welding program is associated with said machine, said program being implemented as a function of the data contained within the identification codes. The data are defined on the basis of a welding law or standard to be applied as a function of various values for parameters relating at least to the thickness and diameter (or cross section) of the part considered at its abutment end, to the temperatures, lengths of time and welding pressure to be employed, the type of material constituting the part and the index or range of indices of fluidity of said material therefore defining the dynamic viscosity so that it would be possible to butt-weld tube parts if the codes of the parts are recognized as being compatible per se. In addition, it is necessary to be able to prohibit welding if the codes are recognized as being incompatible. Application to the welding of polyethylene tubes in particular.

Prediction of Residual Stresses and Distortions in Welded Structures

Abstract: A good knowledge of the welding residual stress field and the corresponding distortion is needed when the interaction between manufacturing stresses and future (mechanical and/or thermal) design loads is studied, for example, with respect to possible crack initiation and growth in the HAZ, and also with respect to buckling. It is proposed here that a qualitatively good estimate of the welding residual stresses can be obtained by using FEM without following the temperature history during welding and cooling in detail. The procedure proposed is applied to two different problems: multi-pass butt welding of pipes, and spot welding of box beams. For the case of multi-pass butt welding of pipes, experimental results are available and a good agreement with these results is observed.

Laser welding of wire strands to an electrode pin

Abstract: Method and apparatus for butt welding a stranded wire (62) to an electrode pin (50) in close proximity to igniter material using laser beams (66). The wire (62) and electrode pin (50) are preferably part of an initiator assembly used in an airbag system. In a preferred embodiment, the wire (62) is made of copper and the electrode pin (50) is made of a steel alloy. The wire (62) and pin (50) are vertically aligned in contact with each other, without any external force or pressure applied to them. A plurality of beams (66) contact portions of both materials at the same time, causing them to melt, substantially without any melted material extending beyond the width or diameter of the wire.

Method for butt welding at least two metal sheets

Abstract: The subject of the invention is a method for butt welding at least two metal sheets of different thicknesses, by means of a laser beam. The method consists in bringing the metal sheets into contact at their lateral faces to be butt jointed, in directing the laser beam towards the thicker metal sheet so that the vertical axis X--X passing through the focal point P of the laser beam on the said metal sheet is at a defined distance from the joint plane of the metal sheets and in making a welded joint at the butt jointed lateral faces by local melting of the said metal sheets by means of a laser beam.

In-process monitoring in laser welding of automotive parts

Abstract: Spectral study was carried out to characterize laser induced plasma plume in terms of temperature and electron density in CO2 laser welding of mild steel sheet (0.8 mm thickness). The size and local properties of the plasma plume were determined by means of the Abel inversion technique and CCD camera observation. It was found that the height of the hot plasma core was very small, less than 0.5 mm. The maximum electron density in the plasma plume was approximately 1017/cm3 where the absorption loss of CO2 laser beam via inverse Bremsstrahlung was negligible in the plasma plume. In-process monitoring system using multi photo sensors with different aiming angles was developed to monitor CO2 laser welding of automotive parts, and effects of welding parameters including laser power, welding speed, flow rate of shielding gas and focal position were determined on the light intensity emitted from the welding zone. It was demonstrated that weld defects such as underfill and pits in lap and butt weld joints for automotive parts can be successfully detected by the on-line monitoring system.Spectral study was carried out to characterize laser induced plasma plume in terms of temperature and electron density in CO2 laser welding of mild steel sheet (0.8 mm thickness). The size and local properties of the plasma plume were determined by means of the Abel inversion technique and CCD camera observation. It was found that the height of the hot plasma core was very small, less than 0.5 mm. The maximum electron density in the plasma plume was approximately 1017/cm3 where the absorption loss of CO2 laser beam via inverse Bremsstrahlung was negligible in the plasma plume. In-process monitoring system using multi photo sensors with different aiming angles was developed to monitor CO2 laser welding of automotive parts, and effects of welding parameters including laser power, welding speed, flow rate of shielding gas and focal position were determined on the light intensity emitted from the welding zone. It was demonstrated that weld defects such as underfill and pits in lap and butt weld joints for aut...

Method for laser beam welding of multi-layered clad steel sheet

Abstract: PURPOSE:To provide the method where end surfaces of iron/aluminum multi- layered clad steel sheets are welded by the laser beam without forming the brittle metallic compound and the weld zone. CONSTITUTION:In the butt welding of the end surfaces of iron/aluminum double layered clad steel sheets or iron/aluminum/iron triple layered clad steel sheets, the ferrous metallic layer 1 or the aluminum metallic layer 2 and filler wires 6a, 6b of same metal are placed at the butt part, and are irradiated with the laser beam 4 from the top to execute the welding. The irradiation of the laser beam is intermittently executed to control the heat input, preventing the formation of the compound at the weld zone. This constitution increases the width of the multi-layered clad steel sheet. The forming of the joined multi-layered clad steel sheets becomes possible.

Simulation of Welding Deformation for Accurate Ship Assembling (Report II) : Influence of Initial Geometrical Imperfection on Butt Welded Plate(Mechanics, Strength & Structural Design)

Abstract: In this research, a 3-D thermal-elastic-plastic FEM is developed to simulate the out-of-plane deformation caused by one-sided automatic submerged arc welding. Efforts have been made to improve the reliability and accuracy of the FEM calculation. To prevent the phenomenon of transverse-shear-locking, which is observed as overestimation of the stiffness of a plate for a bending problem when solid elements are used, reduced integration method is employed and proven to be effective. A special type of spring-element is utilized to deal with the contact problem between the plate and the working table.Using the 3-D FEM, the effects of various factors, such as gravity, the method of supporting, magnetic constraint and force from the backing near the welding line have been investigated. The results from the numerical simulation can reasonably explain the phenomena observed from the real situation in shipyards. In the case of FCB automatic submerged arc welding which has the feature of large heat input, out-of-plane welding deformation is mainly affected by constraint condition. The gravity of the plate and the backing force have great influences on the shape of angular distortion. Magnetic constraint can reduce the welding deformation effectively.

Butt welding method for clad tubes

Abstract: PURPOSE:To obviate tempering treatment after welding when the clad tubes whose outer layers and inner layers are formed of carbon steel or low alloy steel and stainless steel or high alloy steel, respectively are subjected to butt welding at a setting field. CONSTITUTION:Before butt welding at the laying field, cladding by welding is performed on at least the end faces of the outer layers 1 to form cladding parts 3 by using a stainless steel or high alloy steel electrode and tempering treatment is carried out on base metal outer layer parts which are heat-affected and hardened by welding. At the setting field, the cladding parts 3 of the stainless steel or the high alloy steel are abutted on each other to perform welding.

Multiple spot resistance welding machine for welding wire grids

Abstract: A multiple spot resistance welding machine for the welding of wire grids by direct current comprises several contact electrodes (4.1.1, 4.2.1, 4.1.2, 4.2.2, . . . ) contacting a respectively associated grid point from both sides. The switching arrangement for the simultaneous application of welding current to all contacted grid points exhibits, for each contact electrode pair (4.1.1/4.2.1, . . . , 4.1.5/4.2.5), a welding transformer. Juxtaposed welding electrode pairs are floating with respect to potential in accordance with this invention so that the sole transverse connection is constituted by the transverse wire (1). A separate contact electrode pair is provided for each grid point.

Device for positioning sheet blanks in an installation for the continuous butt welding of said sheet blanks

Abstract: The invention provides a device for positioning sheet blanks (2, 3) in an installation for the continuous butt welding of the sheet blanks (2, 3) by means of a laser beam. The device comprises, on one hand, a conveyor table formed by an alternating arrangement of rails (11) having balls and bands (12) provided with projecting studs (13) evenly spaced apart and, on the other hand, friction means (15) adapted to be applied on the upper face of the sheet blanks (2, 3) and impart to the sheet blanks a movement in translation which is substantially perpendicular to the direction of feed of the sheet blanks (2, 3).

Ultrasonic Butt Welding of Large Metal Plates by Shifting Welding Tip Driving Position

Abstract: Ultrasonic butt welding of large metal plates by means of shifting the welding tip driving position at regular intervals is studied. The ultrasonic vibration source used has eight 15 kHz bolt-clamped Langevin-type lead-zircon-titanate (PZT) transducers of 60 mm diameter and is driven by a 50 kW static induction thyristor power amplifier. Aluminum plate specimens of 6 mm thickness and 100 mm to 400 mm width are joined successfully end-to-end with almost equal weld strength along the weldment. The input power required for aluminum plates is about 2.2 kW/cm2. The power required by one welding process for aluminum and copper plate specimens of 40 mm width is 4 kW/cm2.

Method and device for assembling automobile body

Abstract: PURPOSE: To assemble an automobile body with excellent precision, to facilitate the change of a jig by miniaturization and weight reduction of a welding jig, and to reduce the cost for facility. CONSTITUTION: A plurality of parts constituting an automobile body such as side panel W1, a floor W2, a roof W3 or the like are mutually positioned to a welding jig 3 arranged on each side of an assembly station and held to assemble an automobile body W by mutually welding these parts at a plurality of tack welded parts. A first welding gun 9 to weld a part of the tack welded parts is mounted on the welding jig 3, a welding robot is arranged outside the part where the welding jig 3 is arranged, and a second welding gun 12 is mounted on the robot. The first welding gun 9 consists of an indirect power supply type gun having a power supply terminal 9a which is extended outside, and the power is supplied to the first welding gun 9 by holding the power supply terminal 9a by the second welding gun 1 2. After the welding is executed by the first welding gun 9, the rest of the tack welded parts are welded by the second welding gun 12. COPYRIGHT: (C)1995,JPO

Fatigue life enhancement of butt welds using a thermo-mechanical technique

Abstract: Previous investigations have shown that the introduction of a compressive residual stress at critical locations enhances the fatigue life of welds. In the present study a combination of heat and applied stress is used to induce a compressive residual stress at critical locations such as the weld toe. The theory of the technique is discussed and an experimental study is carried out to investigate the effect of the technique on the fatigue behaviour of transverse butt welded specimens made from C-Mn steel.

Metal-ceramic joining by laser

Abstract: Within the scope of increase in cutting tools efficiency, a CW CO 2 laser beam has been used for butt welding sintered tips containing cobalt and tungsten carbide to a medium carbon steel core After optimization of the laser processing conditions, full penetrating, sound and homogeneous welds are observed Hardness is found to be nearly constant across the entire weld bead cross-section Micrographic observations in the same area show a fine dendritic microstructure; microanalysis (EDS) as well as X-ray diffraction experiments reveal that dendrites contain mainly iron and cobalt, while tungsten has segregated in the interdendritic zone where complex (Fe-Co-W) rich carbides are likely to form

New methods of ultrasonic metal welding

Abstract: New methods of ultrasonic metal welding and characteristics of the welded specimens are studied. For welding of small specimens such as thin wire bonding, the bonding equipments designed using higher vibration frequency and complex vibration welding tips of 90, 120 and 190 kHz are significantly effective. For medium size welding specimens, complex vibration welding tips are also very effective, and one-dimensional complex vibration systems are developed to simplify the complex vibration systems. For welding of large specimens, ultrasonic butt welding methods joining thick metal specimens end to end are effective. Using the methods and large capacity vibration sources and power amplifiers of 5 to 50, 100 kW, thick and large various metal plate specimens are successfully welded. Ultrasonic welding methods using two vibration systems are also very effective, but not mentioned here

Pressure welding quantity detector for high-frequency resistance welding process

Abstract: PURPOSE:To provide the pressure welding quantity detector in the high-frequency resistance welding process capable of detecting accurately and rapidly the pressure welding quantity during welding. CONSTITUTION:An image sensor 2 picks up an image in the vicinity of a welding starting point WS where the molten edge end faces E of an open pipe OP start to come into contact with each other. An image processor 4 obtain the distance L between the welding starting point WS and a welding finishing point WE and an angle theta formed between the edge and faces E based on the image and calculates an approximate value UA of the pressure welding quantity based on the axithmetic expression UA=2Ltan(theta/2).

Method for mounting heating pipe in load oil tank

Abstract: PURPOSE:To provide a method for mounting a heating pipe in a load oil tank wherein connection of the heating pipe by butt welding is facilitated to substantially reduce mounting labor CONSTITUTION:A method for mounting a heating pipe in a load oil tack is characterized by performing unit work for butt welding of the heating pipe 1 of its linear pipe part 2 and U-shaped curved pipe part 3 and for integrally forming the heating pipe 1 with an erection supporting material 4 on a land surface plate to weld a worked unit onto a bottom plate in the load oil tank

Recent M.I.T. Research on Residual Stresses and Distortion in Welded Structures

Abstract: The paper presents a summary of efforts by the Welding Research Group at the Department of Ocean Engineering, M.I.T. The major thrust of the efforts has been to develop technologies of reducing residual stresses and distortion through in-process control. Part 1 discusses reduction of longitudinal bending distortion of built-up beams, reduction of radial distortion and residual stresses in girthwelded pipes, reduction of forces acting on tack welds during butt welding, and reduction of residual stresses and distortion in high-strength steel weldments. Part 2 presents a brief summary of other research studies, including the forming of steel plates by line heating with a high-power laser beam, an intelligent system for flame straightening of panel structures, and the development of a knowledge-based system for minimizing out-of-plane distortion of welded structures.

High strength hot plate pressure butt welding of plastics profiles - by pinching molten flash after welding with blunt blades and forming upset material back on either side of the weld

Abstract: Plastics profiles are first welded by thrusting together the heated ends with free displacement of material to form flash. After a time delay, but before the flash solidifies, blunt knife-like blades are forced together, close to the outer surface of the profiles, leaving a small gap (m) for the flash, and forcing back the `upset' material either side of the weld flush with the original surface contour. This operation is completed during the time in which the material viscosity in the centre of the weld is less than that towards the inner surface,, so that the latter part supports the material displaced by the blades. The inner, unseen, surface is undistrubed. ADVANTAGE - Improves compaction of weld material. Increases weld strength but with min. finishing. Improves weld appearance and avoids sink marks

Butt welding metal foil - by precoating seam area with flux to prevent oxide film formation

Abstract: Foil or metal workpieces (21, 22) are butt-welded together by coating the area of the seam with a flux (25) prior to heating. The welding is effected by a laser beam (26). The flux can be coated on by spraying or painting etc.. USE/ADVANTAGE - Esp. for foil used to cover a roller in a printing machine. The flux prevents an oxide coating developing over the joint which would cause recesses (17) and protrusions (19).

Localised repair of heat exchanger tubes - uses neutral atmos. during welding of replacement section to prevent oxidn. in weld

Abstract: A process is claimed for repairing local deterioration in a heat exchanger tube (20) incorporating at least one damaged part close to one end of the tube fixed in a perforation (32) of a plate of tubes, consisting of:- cutting the tube beyond the damaged part; extracting via the perforation a section of the tube containing the damaged part and its end; introducing via the perforation a replacement section of tube (21); butt welding the replacement section of tube (21) to the remaining tube (20), inside the tube and under a neutral gas atmosphere. Before welding the tube, a confining component (30) for the neutral gas is introduced via the perforation and placed around the region to be welded. USE/ADVANTAGE - The process is used for repairing local damage in heat exchanger tubes, notably those associated with a nuclear reactor which are in particularly corrosive environments and thus subject to local deterioration such as cracking, notably in the zone immediately adjacent to the part of the tubes fixed to the tube plate. The use of a neutral atmosphere during the welding operation eliminates the risk of oxidn. in the weld without the need for intervention in the secondary part of the steam generator and ensures a good quality weld.

Production of special shaped tube excellent in shape property

Abstract: PURPOSE: To obtain a special shaped tube whose dimensions of corner parts are smaller and which is excellent in flatness in planar parts. CONSTITUTION: By rolling using a grooving roll and grinding, Vgrooves G 1 -G 8 which are extended in the longitudinal direction are formed on a strip material S. The strip material S is bent in the width direction taking the V-grooves G 1 -G 8 as valley bending lines, butt welding J or lap welding H is executed in both end parts in the width direction. Then, the V-grooves G 1 -G 8 are preferentially crooked at the time of bending, so the dimensions of the corner parts are smaller and straight-line-like corner parts C 1 -C 8 along the longitudinal direction of the strip material S is obtained. And, since bending stresses that act on the planar parts P 1 -P 8 are mitigated, the planar parts P 1 -P 8 after bending have higher flatness, groove shape or overlapping state is unified and welding condition is stabilized. COPYRIGHT: (C)1995,JPO

Work fixing jig for laser beam welding

Abstract: PURPOSE:To fix works in a short time and to prevent a gap between the end faces of those from widening by positioning and fixing the works by only a few actions quickly carried out after mounting the works on the work receiving surfaces and further, sufficiently abutting the works on each other. CONSTITUTION:This jig is provided with a wedge-shaped stopper members 13 which are moved vertically by springs 12 and push rods 23 at the butt welding position A, two work receiving bases 14 which are supported pivotally on the position in the vicinity of the work receiving surfaces of ends near to the stopper members 13 so that the work receiving surfaces 14a for holding the works 3 on both sides of the stopper members 13 are made oscillatable between a horizontal state and an inclined state to come down toward the stopper members 13 and are always energized by springs so as to proceed to the inclined state and pads 20 which are arranged above those and lowered and moved next to the stopper members 13 by cylinders 18.

Static behaviour of i-beam to box column connections with external stiffeners

Abstract: This paper is concerned with experimental investigations carried out to study the ultimate load behaviour of I-beam to box-column connections stiffened externally. Eight specimens were tested to failure under monotonically increasing load. Different types of stiffener (i.e. external T-stiffeners and angle stiffeners and internal continuity plate stiffeners) were considered in the studies. The connections in all cases were made by butt welding. Ultimate loadcarrying capacity and load-deflection characteristics of these specimens obtained experimentally are compared with the corresponding results obtained by using a non- linear finite element model. Comparisons are also made between the results for different types of stiffener. Different modes of failure for these specimens were observed. T-stiffeners are found to be the most efficient form (A)

Laser welding method for dumping steel plate

Abstract: PURPOSE:To obtain a good bead by butt welding two dumping steel plates holding a thermosetting resin between them with a specific laser welding speed. CONSTITUTION:When dumping steel plates 1 and 2 are integrally formed holding the thermosetting resin 3 between two steel plates and butt welded, the welding speed is determined so as to the width of the bead 5 is about a half of total thickness of the steel plates 1 and 2. The width of the bead means that W on the upper surface of the upper steel plate which is irradiated with a laser beam 6, the welding speed is determined according to the laser output and when the laser output is high, the welding speed is rapid. Thus, the generation of blowhole in the bead 5 is prevented and the good bead 5 is obtained.

Resistance welding method for al-li alloy

Abstract: PURPOSE: To execute the resistance spot welding of Al-Li alloy having less defect of blowhole, undeposited part, etc., by strenghtening welding pressure in the course of applying electricity for spot welding. CONSTITUTION: Al-Li alloy material with Li content of 1-4% is spot welded. Applying electricity is executed as soon as applying the first welding pressure, successively, applying electricity is continued with applying the second welding pressure stronger than that of the first. For example, to keep pressure and time constant and to change electric current, but the welding pressure is 1200kgf for the first welding pressure and 1800kgf for the second squeezing pressure, the time is a welding of 5 cycles and post heating of 8 cycles. By this method, defects of blow hole, undeposited part, etc., remained by the first pressure are vanished by pressing to conduct electricity, eliminating defected parts, a sound nugget is obtained. COPYRIGHT: (C)1994,JPO&Japio

Experimentally Determined Deformations and Stresses in Narrow-Gap and Single-U Multi-Pass Butt-Welded Pipes

Abstract: This paper describes a study of the multi-pass butt-welding of thick-walled pipes. Two different groove shapes were used: single-U and narrow-gap grooves. Strains were measured on both the pipe outer and inner surfaces during and after welding. Residual stresses and radial deflections were measured on the outer surface after welding. Measured parameters of the two different groove shapes are compared and discussed. Residual stresses at the weld center and radial deflections in the narrow-gap pipe were somewhat larger than those in the single-U pipe. The residual stress fields of both types of groove were found to be rotationally nonsymmetrical. The experimentally obtained residual stresses and radial deflections are compared with corresponding analytical and empirical results based on methods described in the literature and with numerical results for the same pipe from a separate study. Deviations between the measurements presented in this study and published results are discussed.

Post-heating device of butt welding machine

Abstract: PURPOSE:To make the time required for a plate seaming constant concerning welding and post-heating processes in the case of allowing sheet metals of various material to flow on the same manufacturing line, and also, to shorten the time. CONSTITUTION:On a truck 20 moving synchronously with a welding torch 32, a rotary type backing member 10 and a heater 13 are mounted, and also, the welding torch 32 and the backing member 10 are opposed across a butt part of a sheet metal 30, and at the time of welding, backing of a welding part is executed successively by the backing member 10, and immediately after the movement of the backing member 10, the welding part concerned is subjected to local post-heating by the heater 13.

Lap and butt joints of dissimilar stainless steels welded by CO2 laser

Abstract: This work concerns the lap welding of dissimilar (AISI 304 - 430, AISI 430 - 304, AISI 316 - 430, and AISI 430 - 316) stainless steels and the butt welding of dissimilar (AISI 304 - 316 and AISI 304 - 430) ones using a fast axial flow 2 kW cw CO2 laser (B.O.C. Laser Ltd.). Two covering gases, He and N2, are used fed coaxially to the laser beam through a 12 mm outlet diameter nozzle at a flow rate varying from 1.67 to 1.87 X 10-3)m3/s. The influence of the process parameters, such as power level, covering gas, and speed on the quality of the welded joints is examined. In the second part of the work laser lap and butt welds of dissimilar stainless steels are characterized by macro and micro graphic investigations to enable structural evaluations. Fillet weld morphology and quality of the same specimens is examined for the two different covering gases, He and N2. Moreover, the different structural aspects of the melted zones obtained with laser welds of the same pair of stainless steels, but with the beam impinging first on the austenitic stainless steel (e.g., AISI 304 - 430) and then the ferritic one (e.g., AISI 430 - 304), or vice versa, are also studied and evaluated.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.