A kind of submerged welding process
Technical field
The present invention relates to the butt welding process that thickness of slab is not more than the plate of 14mm.
Background technology
In the shipbuilding process, when the plate of thickness of slab below 14mm carried out butt welding, general shipyard mainly adopts following two kinds of methods: one, the semi-automatic CO2 protection of employing weldering, the method divides the welding of four roads to finish, four roads all weld with semi-automatic CO2 protection with semi-automatic CO2 protection weldering or front twice, rear twice submerged-arc welding, advantage is that the weld seam terminal seldom cracks, shortcoming is that welding sequence is complicated, production efficiency is low, and because electric arc can not heat on groove sidewall both sides all the time, arc energy is not enough, causes deposition rate low; They are two years old, adopt FCB high-efficiency welding method (i.e. the two molten bath submerged-arc weldings of two arcs), in the method welding process without arc light, few flue dust, production efficiency is high, but it must use dual power supply, and current ratio is larger, the increase of electric current and the insulation effect of solder flux cause heat input to increase (heat input=electric current * voltage/speed of welding), and then the swelling stress of weld seam is increased, finally cause the weld seam terminal easily to crack, and for the plate of thickness of slab 14mm, because the length of electric arc is generally 3mm, can't once arrive the entire depth (14mm) of weld seam, so the method adopts four layers of weldering, divide four layers of butt welded seam to weld to reach welding effect, the significantly increase of power consumption also can cause the raising of production cost in addition, and this is disadvantageous to shipyard.
Summary of the invention
The present invention aims to provide a kind of submerged welding process, enhances productivity, improves the purpose that deposition rate, reduction cost and weld seam terminal are difficult for cracking to reach.
A kind of submerged welding process of the present invention comprises the step of following order:
A, left and right two plates position to be welded is processed, form groove;
B, with the docking of left and right two plates, check the fit-up gap of left and right two plates, make the fit-up gap of left and right two plates meet required precision;
C, at the left and right two plate joint back sides liner is set, and liner is fixed;
D, use Lincoln weld dolly weld, in the welding process, this dolly moves with uniform velocity along weld seam, welding wire on the dolly is when moving with uniform velocity with dolly, the control welding wire is done backward at the uniform velocity reciprocally swinging with respect to dolly along bead direction, and the amplitude of control wire oscillation, the swinging arc of welding wire is in the scope of molten bath all the time; And adjust the welding wire height, when guaranteeing that welding wire is positioned at the front point of swinging arc, electric arc can directly act on the groove root.
Submerged welding process of the present invention is not more than the plate of 14mm for thickness of slab.In the welding process, when welding wire was positioned at the lowest part of swinging arc, also namely the most front some the time, arc energy directly acted on the groove root, makes the fusing of groove root, formed the bottom weld seam with the scolder of fusing; Along with welding wire swings along bead direction backward, this moment, welding wire was done retarded motion with respect to plate, the welding wire bottom is the camber line lifting gradually, also improve gradually along swinging arc in electric arc and molten bath, the metal molten that the groove higher part is divided, form new weld seam with the scolder of fusing, be filled on the weld seam of bottom, thereby increase the weld seam packed height.Welding wire is in the process that swings backward, the relative plate retarded motion of welding wire, molten metal and scolder have the possibility that tumbles forward in the molten bath, however the electric arc that swings backward has very strong digging force, under the effect of strong digging force, it can avoid molten metal and scolder to sidewinder forward; Thereby also contact the groove root and form the first weld seam because molten metal and scolder tumble forward the very first time with regard to having avoided, because the weld seam that this situation forms can be crossed low poor quality because of formation temperature, crack easily.In addition, when welding wire swings forward, do accelerated motion with respect to plate, deposite metal and scolder be because effect of inertia can be stayed the rear side in molten bath, and welding wire can arrive point before the molten bath prior to the deposite metal, can guarantee that arc energy directly acts on the groove root, make the fusing of groove root, form the bottom weld seam.This welding manner has not only significantly improved the mining ability of electric arc to the molten bath, the welding of whole weld seam can be finished by welding together, simplified welding sequence, improved production efficiency, and welding arc to the molten bath forward and backward 2 in turn effect so that in butt-welding process electric arc continue groove sidewall both sides are heated, solved the problem of arc energy deficiency in the semi-automatic CO2 protection weldering, deposition rate is higher; With respect to the FCB high-efficiency welding method, the needed welding current of this technique is about its half, when other conditions are constant, heat input also is reduced to half thereupon, and then the swelling stress of weld seam declines to a great extent, and the weld seam terminal is difficult for cracking, and the required electric current of this technique is smaller and use single supply simultaneously, the electric energy that consumes reduces, and production cost reduces.
The gap distance from bottom of left and right plate is 2-4mm, and when plate gap distance from bottom during less than 2mm, welding wire is along weld seam swing difficult, and welding wire and electric arc do not arrive default application point, can't carry out useful effect to the forward and backward point in molten bath; When plate gap distance from bottom during greater than 4mm, the molten bath is unstable when causing welding easily, finally causes negative shape bad, and the simultaneously use of wlding increases the rising that also can cause production cost.
The specific embodiment
Embodiment one
Two plates position to be welded is processed, form 15 ° groove; Two plates dock, and check the fit-up gap of two plates, and the gap distance from bottom is 2mm; Refer to liner at the joint back side, and liner is fixed; Use the Lincoln weld dolly to weld, in the welding process, this dolly moves with uniform velocity along weld seam, welding wire on the dolly is when moving with uniform velocity with dolly, the control welding wire is done backward at the uniform velocity reciprocally swinging with respect to dolly along bead direction, and the amplitude of control wire oscillation, the swinging arc of welding wire is in the scope of molten bath all the time; And adjust the welding wire height, and when guaranteeing that welding wire is positioned at the front point of swinging arc, electric arc can directly act on the groove root, and the hunting frequency of welding wire is set to 100 beats/mins.
The common bevel angle of FCB high-efficiency welding method is 50 °, plate gap distance from bottom is 6mm, the present embodiment bevel angle is 15 °, plate gap distance from bottom is 2mm, by contrast, the weld seam volume that needs to fill reduces, and needed wlding reduces accordingly, has further reduced production cost; When bevel angle less than 15 °, plate gap distance from bottom is less than 2mm, welding wire is along weld seam swing difficult, welding wire and electric arc do not arrive default application point, can't to molten bath forward and backward some effect, affect welding quality.
The pass of the swing linear velocity V of wire oscillation frequency f and welding wire is V=2 Π R*f, R is the pendulum radius of welding wire, R is definite value: during the welding wire swing, if the frequency that swings is excessively slow, then the swing linear velocity of welding wire reduces, and the number of times of the forward and backward point in arcing molten bath reduces in the unit interval, and the received heat of forward and backward some unit interval of molten bath reduces, the time lengthening that needs welding, production efficiency reduces; If the frequency that swings is too fast, then the swing linear velocity of welding wire increases, although the heating times of the forward and backward point in molten bath increases in the unit interval, but the too fast electric arc that causes of frequency is unstable, effectively heating times can reduce on the contrary, and the heating of the forward and backward point in molten bath can not get equally ensureing, affects welding quality.Show that through test of many times the set of frequency of swing is 100 beats/mins, can guarantee the stability of electric arc, can obtain higher production efficiency again.
Embodiment two
The angle of groove is set to 30 °, and the distance of bottom, plate gap is 4mm; Other are identical with embodiment one.
Than the FCB high-efficiency welding method, present embodiment bevel angle and plate gap distance from bottom are still less, and the weld seam volume that needs to fill reduces, and needed wlding reduces accordingly, has reduced production cost; When bevel angle greater than 30 °, plate gap distance from bottom is during greater than 4mm, the molten bath is unstable when causing welding easily, finally causes negative shape bad, the simultaneously use of wlding increases the rising that also can cause production cost.
Except above embodiment, satisfying under the stable prerequisite of electric arc, can adjust by cycle of oscillator on the dolly is set the hunting frequency of welding wire, it is shorter that cycle oscillator arranges, the hunting frequency of welding wire is faster, and the linear velocity of wire oscillation is larger, helps the raising of welding efficiency; Otherwise, when electric arc is unstable, with cycle oscillator arrange longer, then the hunting frequency of welding wire is slack-off, the linear velocity of wire oscillation is also slack-off, makes electric arc get back to stable state.The stability of electric arc can characterize by the domain of walker of weldingvoltage, and in welding process, when weldingvoltage floated in the 1V scope in the difference of maximum and minimum of a value, electric arc was stable, and the numerical value of weldingvoltage can read by the voltmeter of dolly.