Method of arc welding
(57) Abstract:Usage: the invention relates to the field of arc welding and can be used in industry, which uses welding seams in different spatial positions. The inventive when implementing the method on the arc and the metal molten weld pool impose external longitudinal industrial frequency (50 Hz) magnetic field. For generating a magnetic field using a simple, reliable in operation and inexpensive equipment. Arc welding perform a constant current of either polarity. The magnitude of induction of the alternating electromagnetic field of industrial frequency is determined from the expression:
< / BR>where Loand L are the length of the molten metal weld pool without magnetic field and when welding in a magnetic field; K - coefficient of proportionality. 3 table. The invention relates to the field of arc welding and can be used in industry, which uses welding seams in different spatial positions and other structures having annular seams (e.g., pipelines).There is a method of welding of girth joints of pipes of small diameter, in which the water of reduced diameter (Akulov A. I. Belchak, A. Demyanovich VP Technology and equipment for fusion welding.- M Engineering. 1977. 432 C.). However, the use of such modes reduces the productivity of welding. In addition, increases the probability of formation of defects such as incomplete fusion, reduced depth of penetration, etc.A known method of controlling the formation of a seam using pulse welding (Erokhin, A. A. fundamentals of fusion welding. M. engineering, 1973, 448 C. ), wherein due to the periodic cooling and fractional crystallization of the melt bath creates conditions that prevent runoff of liquid metal.However, when pulse welding experience significant dynamic effects on the metal melt in the momentum, and there is a risk of disruption in the formation of a seam. In addition, for pulse welding requires a special power supply of the welding arc, which are expensive and require specially trained personnel to maintain and work on them.Known also closest in the combination of features of the method of arc welding of aluminum alloys.with. USSR N 1703325, CL 23 To 9/167, 1989), including welding TIG electroelectronic field served at the moment of the polarity of the half cycles of the welding current.However, in the known method perform welding only aluminum alloys non-consumable electrode, which limits its technological capabilities. In addition to the implementation of the welding method, you must use a special sophisticated equipment generators to negotiate electromagnetic pulses with straight polarity welding current. The known method does not effectively act on the regulation of the length of the weld pool, which limits its wide use in welding seams in different spatial positions of the structures of ferrous and non-ferrous metals and alloys.The task to be solved by the invention is the ability to ensure effective regulation of the length of the weld pool in arc welding in various positions of metals and alloys and the use to implement conventional industrial equipment for welding consumable and non-consumable electrodes.In the method of arc welding with arc and metal weld pool effect longitudinal alternating electee field of industrial frequency imposed regardless of the polarity of the welding current, the magnitude of the magnetic induction (B) the electromagnetic field is determined from the expression
< / BR>where Loand L the length of the molten metal weld pool when welding without magnetic field and magnetic field, respectively;
To the coefficient of proportionality.It is known that in arc welding of heat and mass transfer in metal molten weld pool depends on the direction and intensity of convective flows, which determine, in particular, the geometrical dimensions of the weld pool (length, width, depth).Convection is mainly the result of mechanical action of the arc flow (dynamic forces) and three-dimensional electromagnetic force (Lorentz force) resulting from the expansion of the flow field in the liquid metal.When exposed to the welding zone of the outer longitudinal industrial frequency (50 Hz) magnetic field changes in the character of motion of the liquid molten metal weld pool and the arc column.Such changes caused by the emergence of additional surround the electromagnetic force (F), which is defined by the expression
< / BR>where j is the current vector;
In the range of complete vector is of the form (consumable or non-consumable) and the brand of the electrode material or product, and is determined only by the magnitude and direction of the current density in the electrode and the magnetic induction vector. When changing the polarity of direct current on the welding current changes only the direction of the force. When welding with direct current of a given polarity, the direction of the force F will be determined by the direction of the vector of magnetic induction, the frequency of change of direction is equal to the frequency of the magnetic field (50 Hz).In the electromagnetic effects in the melt occurs vibration associated with periodic changes in the direction of the force F. however, due to the relatively large inertia of the liquid metal melt, appreciable reverse flow in the weld pool is not observed.Such vibration, first, reduces the intensity of the natural axial flows from the head to the tail of the welding bath; second, it allows disperse heat flux, to reduce the temperature gradient in the volume of the bath, to cool the metal, to reduce the degree of fluidity and, therefore, reduce the length of the bath.In addition, the magnetic field influences the shape and motion of the pole of an electric welding arc. Arc is almost instantaneous pravah this leads to a spatial change in position of the arc and the dispersal of heating spot on the surface of the product. This reduces the length of the molten metal weld pool.In the proposed method for generating the electromagnetic field of industrial frequency (50 Hz) does not require special frequency converters, which significantly increases the economic efficiency of the method compared to the prototype. The use of a constant (in magnitude and direction) of the welding current can impose a magnetic field on the arc and the metal of the weld pool during the whole cycle, not according to its direction, frequency, and pulse duration of the welding current, and greatly simplifies the implementation of the method.When implementing the method used the following equipment and materials:
welding automat ADP-1002
the power source of the welding arc BKSM-1000
the power supply of the electromagnet TD-300
a tungsten electrode with a diameter of 3 mm VL
electrode wire SV-A
shielding gas argon
Submerged arc welding with consumable electrode was carried out on plates of low-alloy 10HSND and stainless HTM steels with thicknesses of 20 and 10 mm, respectively. Welding with a consumable tungsten electrode in argon were performed on plates of became nawiliwili the feed speed of the electrode, the speed of welding current and arc voltage. Was napravlyali seam and not armored crater was determined by the length of the weld pool. After complete cooling plate repeated the surfacing of the same modes, but using an external longitudinal magnetic field at different inductions and measured the length of the bath.Modes of welding, and electromagnetic welding processing baths in the table.Notes. 1. The length of the liquid molten metal weld pool was determined according to five independent measurements. 2. Increased induction of more than 100 MT in some cases led to the disruption of stable protection of the weld metal.Based on the experimental data (see tab. 1), it is easy to determine the equation of the length of the bath (PL. 2), for each experiment, respectively.As follows from the obtained experimental results, the length of the weld pool in a magnetic field, with increasing induction decreases linearly and is described by the equation L=Lo-kB. Constant coefficient (k) depends on the parameters of the welding mode.The length of the bath (Lo), the corresponding welding without magnetic field, you can determine experimentally (as in our the ke. M. the motor cycle", 1951 296 S.).Was welded pipes with a diameter of 100 mm with a wall thickness of 2 mm of steel HTM. Swivel ring butt joints in the underlying technology performed a tungsten electrode with a diameter of 3 mm in argon filler wire diameter 1.2 mm HAS on the modes presented in table 3. For welding used the following equipment: rectifier VD-306, welding head STS-220.Note. The argon consumption for all modes of welding 8 10 l/minThus, to reduce the length of the liquid bath, to keep it from draining when welding in various positions, including welding circumferential seams, you can not only due to changes in thermal power of the arc, but due to overlay on a metal melt of the external longitudinal magnetic field of industrial frequency (50 Hz). Method of arc welding with arc and metal weld pool effect longitudinal alternating electromagnetic field, characterized in that the welding are at a constant current of either polarity and use the electromagnetic field of industrial frequency, the value of B induction electromagnetic fields are selected according to the formula
< / BR>where Lis responsible;
K is the proportionality coefficient.
FIELD: restoration of parts cast of aluminum alloys with use of fusion welding.
SUBSTANCE: method comprises steps of cutting out flaw containing portion spaced equidistantly by distance (3 - 8)n from boundary of flaw; making insert of deformed aluminum alloy welded with casting alloy of restored part at relation of coefficients of percentage elongation Gd/Gc = 9 - 25, where Gd and Gc coefficients of percentage elongation respectively of deformed and casting aluminum alloys, n - thickness of cast part in restoration zone.
EFFECT: lowered labor consumption at restoring parts of aluminum alloys.
3 dwg, 1 tbl
FIELD: processes for making large-size thick-sheet orthotropic plates of carbon low-alloy steels in different branches of industry, particularly for bridge building.
SUBSTANCE: method comprises steps of relative orienting members of orthotropic plates; tack welding oriented members by means of non-consumable tungsten electrode in mixture of shield gases Ar (95 - 97)% + (3 - 5%) CO2 ; performing automatic continuous-seam welding and then trimming surface of welded seam. It allows simplify method for making welded large-size thick-sheet orthotropic plates of carbon low-alloy steels.
EFFECT: lowered labor consumption, shortened time cycle for making enhanced-quality plates, improved reliability of welded structures.
6 dwg, 1 ex
FIELD: electric arc welding of materials by means of non-melting electrode, namely methods for automatic argon-arc pulse welding of steel tubes.
SUBSTANCE: method comprises steps of preliminarily dressing tube butts and forming annular chamfers on inner surfaces of butts; abutting tubes; moving welded edges relative to electrode by step axial rotation of abutted tubes at revolution number 1 -1.5 rev/min; igniting arc 2 - 5 s before starting rotation of tube in order to heat welded seam zone; performing welding by means of torch inclined to tube axis by angle 60 - 85° relative to vertical line; sustaining electric current intensity in range 110 - 155 A for pulse duration 0.7 - 0.9 s; keeping electric current at pause period in range 10 - 30 A for pulse duration 0.5 - 0.7 s. Overlapping value of welded seam is in range 10 - 25 mm. It allows eliminate cracking of welded seam of tubes at bending samples by angle exceeding 160°.
EFFECT: enhanced quality of welded seam of tubes.
3 dwg, 1 tbl
FIELD: automatic welding increased-thickness joints of titanium alloys in inert gas by means of submerged tungsten electrode.
SUBSTANCE: method comprises steps of forming in welded edges cutout which is in the form of П-shaped dressing of edges at welding parts with slit gap; keeping relation of depth of dressing to its width less than 1; rounding acute angles of dressing; before welding introducing granulated additive material into slit gap and performing first pass at minimally admissible value of shape factor of fusion. In order to provide guaranteed fusion of walls, second and third passes are realized in the same mode. Electrode is placed in such a way that it is shifted relative to butt axis. At double-side welding passes are realized according to next order: first and second passes, then third, fourth and fifth passes.
EFFECT: enlarged manufacturing possibilities of method due to increased limit thickness of welded parts.
3 cl, 5 dwg
FIELD: machine engineering, possibly gas-shield electric arc welding by means of non-consumable electrode.
SUBSTANCE: method comprises steps of alternatively feeding several gases or their mixtures by pulses; at each next pulse feed using gases (gas mixtures) having ionization potentials different in comparison with those of gases or gas mixtures of previous pulse feed; periodically changing electric arc gap simultaneously with gas feed pulses; setting basic voltage of electric arc equal to optimal voltage in medium of gas or gas mixture with minimum ionization potential; setting difference between maximum and minimum voltage values of arc at periods of previous and next pulse feed of gases or gas mixtures in range 1 - 7 V.
EFFECT: enhanced quality of welded joints, possibility for adjusting fusion depth.
1 tbl, 1 ex
FIELD: gas-shield welding process with use of non-consumable electrode, namely torches for such welding.
SUBSTANCE: torch includes body of collet chuck holder. Said body has cylindrical surface near its working end and it is welded to electrically conducting gas conduit. Collet chuck is mounted in body for securing non-consumable electrode. Nozzle has cylindrical surface passing to cone surface and then again passing to cylindrical surface near its working end. Asbestos-cement insulator is arranged on surface of body of collet chuck holder; brass sleeve is put onto said insulator. Insulator is fixed to body by means of pressure ring-splitter having cylindrical surface passing to cone surface with radial openings.
EFFECT: possibility for making small-size torch for welding butts of metallic structures in hard-to-reach places of installation zone.
FIELD: plastic working of metals, namely processes for forming butt welded seams on tubes at making tube studs of U-shaped tube bundles using effect of localized hot plastic deforming of welded seam and near-seam zones.
SUBSTANCE: method comprises steps of preliminarily working tube ends by expanding them from cylinder to cylinder; assembling tubes with use of mandrel and placing intermediate member of additive material between joined end surfaces of end portions of tubes sized by expansion and end surfaces of step ring. Welded seams are formed by argon-arc welding due to melting material of intermediate member at its both sides adjacent to tube ends. The intermediate member is heated up and it is subjected to hot radial squeezing while concentrating its initial deformation in surface layers according to position of ring steps, welded seams and near-seam zones on mandrel for providing size of their outer diameter equal to initial outer diameter of tubes.
EFFECT: improved quality of welded seams.
FIELD: mechanical engineering; argon-arc welding.
SUBSTANCE: invention relates to methods of automatic argon-arc welding of austenitic steel pipes in manufacture of important constructions, such as high-pressure pipes used at nuclear power stations. Proposed method includes mechanical preparation of welding surface zone, veeing edges to miter of 3.0-3.5 mm and subsequent multiple-pass welding with nonconsumable negative electrode using filler wire. Welding edges are veed to miter of 2.7-3.0 mm. Welding at first pass is carried out with heat input of 0.35-0.55 MJ/m by impulse current. Welding at second pass is done with heat input of 0.6-0.86 MJ/m by impulse current at cross oscillations of electrode. Welding at third and subsequent passes is carried out with heat input of 0.62-1.16 MJ/m by steady current with cross oscillations of electrode.
EFFECT: increased capacity art welding and quality of weld joint owing to reduction of intercrystalline cracking of weld joint.
FIELD: mechanical engineering; welding.
SUBSTANCE: invention relates to design of torches for gas-shielded arc-welding by nonconsumable electrode. Proposed head of torch contains chuck with hole for electrode secured in body and gas fed channels, nozzle and partition arranged inside nozzle and formed by pack of gauzes. Gauze partition is made convex relative to welding arc flame. Head is furnished additionally with partition made of pack of gauzes arranged between chuck and gauze convex partition and made concave relative to flame of welding arc. Packs of gauzes are made of stainless steel of 3 to 5 layers. Gauze mesh is 0.3-0.5 mm.
EFFECT: provision of high quality of welding at relatively simple design.
5 cl, 2 dwg
FIELD: technological processes.
SUBSTANCE: invention concerns electric arc welding, particularly method of automatic argon arc welding of overlapping joints of steel pipes by non-melting electrode. The method involves preliminary pipe edge preparation and welding by tilted electrode with pipes rotating against electrode to form weld seam. Axial rotation speed of welded pipes is 0.1-0.8 rpm. Electrode is tilted in two planes: by 50-70 degrees against the article axis and by 60-85 degrees against weld seam plane.
EFFECT: improved quality of weld seams in overlapping joints of steel pipes, reduced hopping during rotation of long-length welded article, reduced cost of welded product.
3 cl, 3 dwg, 1 tbl