Showing papers on "Welding published in 1980"

Metallurgy of Welding

Abstract: The effect of surface forces on the bonding of materials. Solid-phase welding and adhesive joining. Soldering and brazing. The joining of ceramics: microjoining. Fusion welding: processes. Fusion welding: mass and heat flow. Metallurgical effects of the weld thermal cycle. Carbon and ferritic alloy steels. Austenitic and high-alloy steels. Non-ferrous metals. The behaviour of welds in service.

Method and apparatus for manipulator welding apparatus with vision correction for workpiece sensing

Abstract: Control apparatus for manipulator welding apparatus is provided that includes a vision correction system for workpiece sensing. During an initial teach mode, the manipulator is taught the desired welding path on a workpiece by the appropriate recording of data representing the welding path as an operator controls movement of the manipulator. In addition to the data representing the taught welding path, data representing a reference image or template is also recorded in the teach mode. The reference image or template data is provided by a vision system including a camera carried by the manipulator arm. As successive workpieces are presented to the manipulator for performing the desired welding path, in a repeat work cycle mode the manipulator is controlled to move in accordance with the recorded taught data in a first repeat pass wherein images of the welding seam region are detected at successive points. The vision system utilizing an image processor detects the deviation between the taught welding path and the actual welding path of the workpiece. The control apparatus in response to the deviation data provided by the image processor in the first repeat pass corrects the recorded taught data to provide corrected welding path data for the particular workpiece orientation and geometry encountered by the manipulator. During a second repeat pass of the repeat work cycle mode, welding of the actual workpiece seam is performed in accordance with the corrected welding path data obtained in the first repeat pass.

Occupational asthma due to stainless steel welding fumes.

Abstract: Summary Seven patients with respiratory symptoms after welding were examined. Five had occupational asthma caused by fumes from manual metal are stainless steel welding. The detailed clinical results of two patients with repeated challenge tests are reported. One patient was nonatopic and had earlier had contact dermatitis due to chromium. He experienced a non-immediate type of asthmatic reaction after welding stainless steel. The other patient was atopic and showed an immediate-type reaction. Both reactions were repeated in the second provocation lest after about 2 years. In addition both disodium cromoglycate and beclomethasone pretreatments inhibited the reaction of the two patients, but a placebo medication did not. A remarkable amount of chromium and nickel are detected in the fumes released during stainless steel welding but not in the fumes from mild steel welding, with which all provocation tests were negative. The chromium or the nickel in welding fumes might be the aetiological factor of the reaction.

A mathematical model for fluid flow in a weld pool at high currents

Abstract: In order to determine the heat transfer inside a TIG (tungsten/inert gas) weld pool, it is necessary to have a good understanding of the flow patterns of the liquid metal. The principal force driving the fluid motion is the electromagnetic j × B force due to the current from the welding arc and its self-magnetic field. In this paper we consider the flow of a viscous incompressible conducting fluid in a hemispherical container due to various distributions of the electric current. The problem is posed as a time-dependent problem and is solved numerically using the Du Fort–Frankel leap-frog method. Results are presented for currents of 100 A flowing through the weld pool. This is a typical current for TIG welding, and corresponds to a Reynolds number in the range 200 < Re < 600. Previous solutions of the problem were restricted to low Reynolds numbers, i.e. low currents.

Controller for spot welding

Abstract: A controller for a spot-welding machine compares the temperature evolution at a site at which a spot weld is being made to a standard thermal history stored in a digital read/write memory in controlling the welding current for the weld. Standard thermal histories can be generated and written into the memory as needed by an operator of the welding machine to take into account changes in operating conditions. The temperature evolution of the spot-welding operation is monitored by detecting radiant energy whose intensity provides a measure of a temperature of the weld. Phosphorescent radiation from a thermographic phosphor located in a welding tip of the welding machine and thermal infrared radiation are preferred for monitoring the temperature evolution of the spot-welding operation.

Principles of Welding Technology

Abstract: The 3rd edition of this textbook, which has been updated to take into account the new developments in welding technology, changes in safety requirements, and changes arising from the harmonisation of British and international standards.

Hot plate welding of plastics: Factors affecting weld strength

Abstract: Welded joints were made under a range of conditions in polypropylene, glass fiber reinforced polypropylene and poly (methylmethacrylate) bars. Melt flow in the weld was investigated by microscopy and by contact microradiography, and weld strengths were measured by tensile tests. The fracture toughness of the weld zone was determined by tests on double edge notched specimens. The study shows that weld strength is strongly affected by hot plate temperature, heating time and melt flow during welding. Insufficient heating or melt flow results in incomplete bonding. Excessive melt flow produces strong transverse orientation. Both reduce strength, but in different ways, which can be distinguished by fracture mechanics tests.

Gas metal arc welding system

Abstract: Power delivered to the welding arc from a constant current rapid response power supply is controllable to maximize arc stability particularly in out-of-position welding operations. A first control modulates the output current from the power supply between a high value close to the maximum output value and a minimum value just sufficient to maintain the welding arc. The modulation is effected at a given frequency appropriately adjusted in accordance with the electrode material and diameter to maintain optimum spray metal transfer in the welding arc. A further control is effected by pulse width modulating the output from the power supply in accord with a set-in current programmed signal which is compared with a current feedback signal or, alternatively, a set in voltage programmed signal which is compared with a voltage feedback signal. This latter control provides for operation of the power supply in a constant current control mode or alternatively, a constant voltage control mode. Still further control of the power in the welding arc is effected by pulsing the current between base and peak levels at a relatively low frequency which enables control of the weld puddle in out-of-weld positions.

Position regulation of a charge carrier beam

Abstract: In a charge carrier beam machine, as an electron beam welding machine, a system for establishing the relative position of a beam impingement spot on a workpiece surface and a machine reference position, as a beam gun axis, comprises an X-ray sensor defining at least one measuring field boundary intersecting the workpiece surface at a line of intersection spaced from the gun axis. During repetitive measuring periods, the beam is deflected from the normal working position along a measuring path, which crosses the line of intersection, and a signal functionally related to the period of time the beam needs to travel from a reference position along the measuring path to the line of intersection is produced. This signal comprises the desired information about the relative position and can be used in a regulating apparatus for maintaining a desired relationship. Two sensors having differently oriented measuring field boundaries can be used to detect any deviations of the workpiece surface from a desired plane and the output signals of these detectors are useful for maintaining a desired positional relationship between a welding site and a filler wire supplied to the welding site. The shape of the cross-section of the beam may be altered during the measuring period to improve the accuracy of the measurement.

Method for producing clad steel pipes

Abstract: Title of the Invention Method for producing clad steel pipes A long length clad steel pipe which is in the extremely superior metallurgically bonded state and having good qualities can be manufactured easily in an inexpensive cost by using as a base metal, a carbon steel including a low alloyed steel and as a cladding metal, a stainless steel, nickel or a nickel alloy and by the steps comprising welding at least one end part of double pipes consisting of a base metal and a cladding metal, and subjecting the processed double pipes to hot rolling at a temperature between 850.degree.C to 1300.degree.C with a reduction ratio of at least 15% in the first step rolling.

Composite wire for gas shielded arc welding

Abstract: PURPOSE: To execute vertical up welding with high efficiency and to obtain the composite wire which has the good migratability of droplets and decreases the amt. of the spatters to be generated by specifying the grain size constitution, incorporating TiO 2 at a specific ratio into the wire and incorporating specific components at specific ratios therein. CONSTITUTION: A flux is filled in the sheath made of a steel. The grain size constitution is so specified that the particles having the grain size exceeding 149μ are incorporated into the wire at 10wt.% and the particles having 44μ grain size or below at ≤30wt.%. The TiO 2 is incorporated into the wire at 3.5W7.0wt.% of the total weight of the wire. Further, contains 0.4W1.0wt.% ZrO 2 , 0.1W1.0wt.% Al 2 O 3 , 0.3W1.0wt.% Si, 1.2W3.2wt.% Mn, 0.1W0.6wt.% Al, 0.03W0.3wt.% total of 1 or 2 kinds of Na, K:Na, K, and 0.01W0.2wt.% F. The vertical up welding is thereby executed with high efficiency and the amt. of the spatters to be generated is decreased; in addition, the working efficiency of welding is improved. COPYRIGHT: (C)1989,JPO&Japio

Liquation cracking during the welding of austenitic stainless steels and nickel alloys

Abstract: Liquation cracking can occur during fabrication by welding in either the heat affected zone in the parent material, or in previously deposited weld metal during a subsequent run. It results from localized melting at grain or other boundaries, combined with the thermal strains associated with welding. This review paper opens with brief descriptions of the classification, identification and mechanisms of liquation cracking. Following an outline of the material classes and circumstances in which it is most likely to occur, compositional influences in austenitic stainless steels and nickel alloys are considered in more detail. It is emphasized that although residual elements such as S, P or B may have an important role in causing or enhancing liquation effects, much liquation cracking is associated with intentional minor alloying additions, such as Nb. The influence of deliberate alloying additions, and compositional balance, in limiting the influence of residuals will be considered. In conclusion the detection, significance and avoidance of liquation cracking are discussed briefly.

Electrical contact material

Abstract: PURPOSE: To obtain an electrical contact material having a superior consumption resistance and superior welding resistance by adding a specified percentage of Ni to Ag and by dispersing a specified percentage of a transition metallic carbide. CONSTITUTION: To Ag is added 10W60wt% Ni, and 0.0001W0.5wt% in total of 1 or ≥2 kinds of transition metallic carbides is dispersed. By adding Ni, welding resistance and low contact resistance are provided. By dispersing transition metallic carbides, when electrical contacts are brought into contact with each other and separated, the compounds are allowed to precursively generate arc. Accordingly, arc is dispersed over the whole surfaces of the contacts without causing concentration on a point, and the contacts can be uniformly consumed little by little. COPYRIGHT: (C)1983,JPO&Japio

Frictional welding method

Abstract: A wide element(4) with a short length is joined by friction welding to a narrow element(3) with a long length, where one element is rotated against the other(4) to produce frictional heat; the rotation is then stopped & the press increased to make the weld The novelty is that prior to the process, element is provided with a round hole(5) possessing a smaller dia than the lateral dimension of element(4) The welding press required is reduced only one third that of conventional process

Resistance welding sequence cycle control

Abstract: A method and apparatus are shown for controlling the cycle of a resistance welding device by providing compensation for variations in the effective weld area and the primary input electric power variations through a composite correction applied to the length of the squeeze time cycle portion prior to the weld cycle portion when weld current is activated. Compensation is made for secondary weld current variations by altering the length of the hold cycle, during which electrode contact is maintained with the work subsequent to the weld cycle portion, to change the amount of heat quenched from the weld zone. Further by sensing the condition wherein either the electrical input or the motive power that drives the movable electrode is beyond correctable limits, the welding cycle is aborted when suitable quality welds cannot be made.

Method of jointing pipes by friction welding

Abstract: A method for jointing two pipes such as an aluminum pipe and a copper pipe by friction welding. The aluminum pipe is inserted into a bore of a ring made of a heat resistant material, the bore having a straight section and a tapered section continuous from the straight section. The copper pipe has a tapered end peripheral surface. The copper pipe is pressed at its tapered end, in a rotating state, against the end of the aluminum pipe so as to expand the latter. As a result, an ironing is effected on the aluminum pipe by the straight section of the bore of the ring, such that the aluminum pipe overlies the straight section of the copper pipe in close contact with the latter. Consequently, the tapered surface of the copper pipe is friction welded to corresponding portion of the aluminum pipe while the latter is being backed up by the tapered section of the bore of the ring.

Low resistance electric joint between conductive members, at least one member having an insulation coating thereon, and the method of making such joint

Abstract: A sound, low resistance joint is provided between two electrically conductive members, at least one having a bonded insulation coating thereon. In one form of the method of the present invention, a continuous metallic penetrator having sharp edges or burrs, such as a brass screen, is interwoven about at least two bonded insulation coated conductive members. The coated conductive members and interwoven penetrator are placed in a conductive connector member having chamfered holes therein. Welding electrodes subject the connector member to heat and pressure with welding current flowing between the welding electrodes. At least some of the welding current flows through the continuous metallic penetrator before the penetrator makes electrical contact to the insulation coated conductive members. The penetrator becomes heated by thermal heat from the welding electroides and resistance heat as the welding current passes therethrough. Heat from the interwoven penetrator melts the bonded insulation from the surface of the coated conductive members, causing the insulation to vaporize. A metallurgical bond is formed between the conductive members, the connector member, and the interwoven penetrator. Excess metal from the conductive members and the metallic penetrator flows through the chamfered holes, forming rivets. Other embodiments are disclosed.

Automatic welding position control method, and device

Abstract: A welding method in which a pair of base metals are welded together by swinging the welding torch right and left, and a device for practicing the method. In the method, the arc current is continuously detected, and sampling pulses are formed in time slots provided by the swinging motion of the torch. The arc welding currents are sampled and held with the aid of the sampling pulses, whereby the peak values of arc currents flowing when the torch is swung right and left are detected, and the position of the torch is correctively shifted right or left according to the difference between these peak values.

Automatic welding robot

Abstract: PURPOSE:To make the general works such as cylindrical shapes and three-dimensional shapes automatically weldable by making any of respectively turnable 1st and 2nd arms and torch mounting means movable axially around the three parallel shafts of an equal inter-shaft distance. CONSTITUTION:The position of the torch T welding point is aligned to the weld line of the works by making the distance L between shafts 15 and 18 equal to the distance between the shafts 18 and 21, positioning the weld point position of the torch T on the centerline of the shaft 21 and controlling an actuator 13, motors 16, 19, 22 with a control unit of a known PTP system. Hence, if an arm 17 is positioned below an arm 14 by driving the motor 19, the shaft 15 and the shaft 21 position on the same straight line, and the torch T welding point positions on said straight line as well. In addition, if the arm 17 is turned 180 deg., the distance between the shaft 15 and the shaft 21 becomes 2L like the alternate long and two short dashes lines. Hence, the moving range of the torch T becomes the range formed within the plane circle of a radius 2L centering at the shaft 15 and general cylindrical and three- dimensional works may be placed within this range and automatically welded.

Apparatus and methods for use in welding

Abstract: Apparatus and methods for use in aligning and welding in end-to-end relation a pair of members such as pipe sections or a cylindrical vessel and closure wall and wherein one of the members is subjected to a clamping force adjacent the end to be welded to produce a predetermined configuration at that end. The other member is supported with that end to be welded confronting the adjacent end of the first member. A clamping force then may be applied to the second member so as to conform its configuration to one corresponding to that of the end of the first member. While maintaining the two members clamped, their positions are adjusted relatively to one another to locate their adjacent ends in a predetermined manner, following which the two members are moved relatively in a direction toward one another to a welding position in which the welding operation may be completed.

Method and apparatus for monitoring and controlling a resistance welding operation

Abstract: A resistance welding controller for dynamically controlling both weld current and weld time in order to achieve a desired ΔR value. The resistance across the weld electrodes is monitored by the controller during the heat-up phase of the weld and compared to target values for minimum resistance (Rmin) and rate of resistance change (dR/dt). If the observed values for Rmim and dR/dt bear a predetermined relationship to the target values, a dynamic correction is made in the percentage heat control setting. The weld is then continued at the revised weld current level until the desired ΔR value is satisfied. If upon weld termination, the observed weld time is greater than the target weld time, an additional correction in weld current is made in preparation for the next weld. In addition, the controller is also adapted to detect newly dressed weld electrodes and automatically respond by reverting to the original weld schedule.

Hot Cracking Resistance of Austenitic Stainless Steel Weld Metals Increasing Mn and Mo content and avoiding multiple thermal cycles on weld metal HAZ can reduce hot cracking tendency of fully austenitic stainless steel weld metals

Abstract: The fissure bend test origi­ nally developed and evaluated for determining the cracking resistance of SMA deposited austenitic weld metals has been extended to evaluate GTA and GMA deposited filler metals. Fis­ sure bend tests were run on several commercial fully austenitic and ferrite- containing stainless welds deposited by GTA, SMA and GMA welding pro­ cesses. The fully austenitic filler metals are basically AISI Type 310 or 316 com­ position with a difference in the alloy­ ing elements Mn, Mo, and C. The effect of nitrogen additions to the shielding gas, in the GTA process, on the ferrite content of the deposited weld metal has been defined. The nitrogen addition technique shows that it is an effective way of reducing and/or controlling ferrite content. Further, that nitrogen additions have relatively little effect on fissuring ten­ dency in the materials evaluated. In fact, it was possible to reduce the ferrite content from 5 FN to 0.5 FN and maintain fissuring resistance. The nature and morphology of the fissuring in fully austenitic stainless steel weld metals is similar to that of the partially ferritic weld metals. The location, extent and magnitude of the cracking is dependent upon procedure characteristics as well as composition. The weld metal heat-affected zone thermal history plays an important role in controlling fissuring tendency in the fully austenitic weld metals. This effect has been evaluated using a multiple thermal cycle technique in the fissure bend test.

Friction welded transition joint

Abstract: A transition joint is disclosed for joining together tubular pieces formed respectively from a low alloy or carbon steel and a high temperature alloy composition having substantially different characteristics such as coefficient of thermal expansion, the transition joint including a plurality of tubular parts interconnected with each other by means of friction weld joints formed at an angle of 90° to the axis of the transition joint, the tubular parts at opposite ends of the transition joint being selected to facilitate in situ welding to the low alloy or carbon steel and high temperature alloy respectively.

Nickel-base welding alloy

Abstract: A welding alloy particularly directed to use as a wrought filler metal and contains selected percentages of chromium, molybdenum, manganese, columbium, magnesium, a number of trace elements and the balance essentially nickel.

Welded structrue having improved mechanical strength and process for making same

Abstract: A welded structure and a method for making same wherein a plurality of weld metals, such as martensitic steel and austenitic steel, differing in coefficient of thermal expansion from each other are deposited in a plurality of layers thicknesswise of the welded structure in a gap defined by structural members to be welded in such a manner that a layer of the weld metal of higher coefficient of thermal expansion is covered by a layer of the weld metal of lower coefficient of thermal expansion in a weld formed, to improve brittle fracture strength, fatigue strength and stress corrosion cracking resistance of the weld. By subjecting the welded structure to stress relief annealing treatment, it is possible to produce compressive stress on the surface of the layer of the weld metal of lower coefficient of thermal expansion.

Panel welding system

Abstract: An integrated welding torch and work positioning roller head assembly is mounted for controlled movement on a cross travelling gantry carriage overlying a vacuum hold-down bed that supports a workpiece panel. The torch and roller head assembly has two related configurations, one for forming a butt weld along a seam joining edgewise abutting sections of flat stock to form a relatively larger unitary panel, and another head configuration for subsequently positioning and fillet welding stiffener webs to one face of the panel. Each of the head assembly configurations is provided with a cofunctioning arrangement of a welding torch (or torches) and seam tracker (or seam trackers) for positioning the torch (or torches) relative to the head assembly as the assembly is automatically guided by the gantry carriage along the intended seam, and a plurality of workpiece positioning and holding rollers which cofunction with the vacuum hold-down bed to form distortion-free panels, having consistently uniform welds along the seams, without the need of preliminary tack welding and without requiring special purpose jigs and tooling for each different panel and stiffener shape.

Bi-metallic thermo-barrier material and method of welding

Abstract: The manufacturing of multi-layer bi-metallic thermo-barrier material utilizing combined brazing and difussion bonding methods of joining together the components of the barrier material.

Method of welding several optical fibers end to end in layers and a device for welding in accordance with said method

Abstract: A method of welding several optical fibers end to end in layers in a common welding plane. Each fiber (31) includes a bared portion and a covered portion. The method is applied by a device including: (a) a microplasma welding torch (40) with a vertical axis movable in said weld plane; (b) a supporting block (39) with: parallel positioning grooves for positioning the bared portions of the fibers; an opening (42) in the neighborhood of the weld plane; and a chamber (43) for slowing down the gases of the plasma disposed below said opening and connected thereto; and (c) components for gripping the covered portions of the fibers said gripping components being constituted by supports (11, 12) provided with parallel optical fiber positioning grooves. A positive pressure difference is set up between the upper portion and the lower portion of the fibers. The fibers are translated parallel to the axes of the optical fibers.

Membrane type low temperature tank

Abstract: PURPOSE:To improve the characteristic by specifying the material and the fixing method of side membrane. CONSTITUTION:On the inside surface of the heat insulating material layer 2, being attached in layers on the side wall of the ferro-concrete body 1, side membranes 3 are established being consisted of the material whose linear expansion coefficient is so small as to be neglected such as 30% Ni steel plate. Both sides of each steel plate are bent inwardly forming flanges 3a extending vertically toward the bottom of the tank, while the adjoining steel plate pieces are connected by flanges 3a each other respectively. Bottom end of each steel plate 3 is fixed to the corner angle 4 and ring member 5 by welding which is anchored to the concrete body 1 thru anchor members. In addition, each steel plate is fixed by welding to the intermediate anchors 8 which are disposed as necessary along the wall toward the direction of the tank bottom. Under this constitution, wedling work for the purpose of restricting the deformation of side membrane 3 which occurs due to the temp. stress is unnecessitated, while the number of support spans against the back pressure is decreased, and in addition, strength against the back pressure is increased, and the deformation to occur at the top edge of the plate is restrained to the minimum.

Hard nickel-base alloy resistant to wear and corrosion

Abstract: Disclosed is a hard wear resistant nickel based alloy including a carbide-former, preferably niobium, and essentially cobalt free but which has similar properties to cobalt, chromium, tungsten, carbon alloys. Typically the alloy has a composition, in parts by weight, Cr-34 C-1.2, Mo-10, Fe-3, Si-1, Nb-3, Ni-balance. The alloys of the invention are suitable for surface or welding consumables, and as articles for making hardfacing depositions.