Unclear Root Welding Process of I-shaped Groove with Unequal Gap in Medium and Heavy Plate

Abstract

The invention discloses a process of welding without back gouging at an I-shaped groove with unequal gaps of a medium plate. The process comprises the steps as follows: an assembling step before welding: the medium plate is assembled, the I-shaped groove with unequal gaps is formed, the groove faces upwards, a root gap of the groove is 0 mm-3 mm, and a front gap of the groove is 0 mm-5 mm; backing welding: backing welding is performed on the front surface of the groove in a small-current swing welding manner, and molten metal doesn't flow downwards during the backing welding; front surface submerged-arc welding: submerged-arc welding is performed on the front surface of the groove with a small current, welding seams of backing welding are not burned through during the front surface submerged-arc welding; and back surface submerged-arc welding: submerged-arc welding is performed directly on the back surface of the groove without carbon arc air gouging; and a current for the back surface submerged-arc welding is determined according to the thickness of the medium plate and the root gap of the groove, the back surface submerged-arc welding realizes complete penetration in a small gap area at the root part of the groove, and the front surface at the root part of the groove is not burned through.

Description

technical field [0001] The invention relates to the field of steel structure manufacturing, more specifically, to the technical field of medium-thick plate welding. Background technique [0002] The medium-thick plate structure is widely used in ship plates and shells, port machinery box girders, and cross-sea bridge decks. Tailored welding of medium and thick plates accounts for a very large proportion in the production of structural parts. The traditional method of tailor welding of medium and thick plates adopts V-shaped grooves, front welding, back root cleaning, and then welding. The welding production efficiency is low and energy consumption is low. High, serious environmental pollution, high cost. Therefore, there is an urgent need for a new high-efficiency, low-carbon I-groove welding process without clearing the root, that is, a welding method that does not open a V-shaped groove and does not clear the root. [0003] At present, double-sided single-pass submerged ...

AI Technical Summary

Problems solved by technology

However, in actual production, since plasma cutting is three times more efficient than flame cutting, it is widely used. However, the quality of the plasma cutting groove is poor, and the verticality of the cutting surface is not high, resulting in a certain groove angle of 5-10° during tailor welding. It is difficult to ensure that the clearance is within 1mm during assembly, and the assembly clearance is inconsistent. Generally, the root clearance is 0mm-3mm, and the groove surface clearance is 0-5mm.

Using the traditional I-type groove submerged arc welding SAW, because the parameters of submerged arc welding are fixed, for the case of unequal gap assembly, when the assembly gap is large, burn-through will occur, and when the assembly gap is small, it is easy to appear incomplete penetration, Pores and other defects, therefore, when the assembly gap is inconsistent, its welding quality is unstable, resulting in the I-type groove welding method cannot be applied

For this reason, in the case of unequal gap assembly of I-type grooves, in order to avoid welding defects, flame cutting or mechanical processing of jigsaw grooves is generally used to control the assembly gap within 1mm to achieve I-type groove welding, but flame cutting Or machined grooves will cause a serious drop in welding production efficiency

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