阅读说明：本技术 一种等离子环缝焊接收孔工艺方法 (Plasma girth welding hole receiving process method ) 是由 李延杰 林全福 翟鹏飞 李光枚 杨凤娟 张波 于 2019-12-25 设计创作，主要内容包括：本发明涉及一种等离子环缝焊接收孔工艺方法,属于等离子焊接技术领域。本发明对等离子环缝焊接起始区段、焊接区段、收尾区段的焊接电流、离子气流、送丝速度进行了研究,焊接区段采用等速缓降电流,减少热输入的方法,有效解决现有电流恒定不变的规范中,末段焊缝热输入累积后造成的焊缝接头组织粗大、外观成形不良的问题,焊缝外观合格率达100%；环缝收尾区段采用焊接电流先升后降、离子气保持先维持再下降的方法,彻底解决由于环缝起弧接头焊缝高、熔不透,而导致背面成形不良、未焊透的老大难问题。焊缝X射线探伤合格率、正反面外观合格率均达100%,易于推广应用。(The invention relates to a plasma girth welding hole receiving process method, and belongs to the technical field of plasma welding. The invention researches the welding current, the ion airflow and the wire feeding speed of the plasma girth welding starting section, the welding section and the ending section, the welding section adopts the constant-speed slow-decreasing current and reduces the heat input method, the problems of thick welding joint structure and poor appearance forming caused by accumulated heat input of the welding line at the end section in the existing specification with constant and unchangeable current are effectively solved, and the appearance qualification rate of the welding line reaches 100 percent; the method that the welding current rises first and then falls and the ion gas is kept first and then falls is adopted in the circular seam ending section, so that the old and difficult problems that the back surface is badly formed and not welded through due to high welding seam and incomplete fusion of the circular seam arcing joint are thoroughly solved. The qualification rate of X-ray flaw detection of the welding seam and the qualification rate of the front and back appearance reach 100 percent, and the method is easy to popularize and apply.)

1. A plasma girth welding hole process method is characterized by comprising the following steps:

step (1), a circular seam starting section:

(1.1) the protective gas is supplied for 5-10 seconds in advance.

(1.2) starting the welding current, the ion gas and the weldment rotation at the same time, rising the welding current and the ion gas, perforating the weldment, forming a pinhole effect in a molten pool, and starting wire feeding;

(1.3) continuously increasing the welding current, the ion gas and the wire feeding speed to reach the normal welding current of 100-350A, the ion gas flow of 0.5-2.8 scfh and the wire feeding speed of 800-2800 mm/min, starting normal welding, and entering a welding section;

step (2), girth welding the section:

(2.1) the welding current of the normal welding section is in a slow-decreasing uniform-speed trend, and the total decreasing amplitude of the current from the beginning of welding to the end of welding of the circular seam welding section is 5-30%;

(2.2) keeping the speeds of the ion gas and the wire feeding constant;

step (3), a circular seam ending section:

(3.1) ring seam tail closing area ascending section: the welding current rises at a constant speed, the total rising amplitude of the current is 5 to 30 percent after the welding is started from the rising section of the circular seam tail-closing area and the welding is finished, the ion gas is kept unchanged, and the wire feeding speed drops at a constant speed; the welding length of the ascending section of the circular seam tail closing area is 30-80 mm;

(3.2) circular seam tail closing area descending section: the welding current is reduced at a constant speed, and the total reduction amplitude of the current is 30 to 70 percent after the welding is started from the descending section of the circular seam tail-closing area to the end; the ion gas descends at a constant speed, the total descending amplitude of the ion gas is 50% -80% after the ion gas descends from the descending section of the circular seam tail closing area by welding, the wire feeding speed descends to zero at a constant speed, and the small hole closing of a molten pool is completed; the welding length of a descending section of the circular seam tail closing area is 60-120 mm;

(3.3) abrupt descending section of the circular seam ending region: the welding current drops to zero at a constant speed, the ion gas drops to zero at a constant speed, the welding receiving arc is completed, the rotation of the weldment is stopped, the gas supply is stopped after the shielding gas lags for at least 10 seconds, and the circular seam welding is finished; the welding length of the steep descending section of the circular seam tail closing area is 30-80 mm;

wherein, the wire feeding speed reduction speeds in the steps (3.1) and (3.2) are the same; and (3.2) and (3.3) the descending speed of the ion gas is the same.

Technical Field

The invention belongs to the technical field of plasma welding, and particularly relates to a plasma girth welding hole receiving process method.

Background

Plasma welding is one of three high-energy beam welding methods which are combined with laser welding and electron beam welding, and is widely applied to various industrial production by the characteristics of high weld joint quality, high efficiency, small welding deformation and high technical maturity. The plasma welding method backing welding or one-time penetration forming process generally adopts a small hole method welding mode to ensure the back forming of a welding seam, so that the welding quality problem exists in a welding seam ending region, the welding defect of the welding seam ending region can be removed by a mode of 'small hole side leading' or arc plate leading-out and the like in longitudinal seam welding, and the small hole can only be closed by a hole closing process method in girth welding. The hole closing process generally adopts a mode of decreasing current and plasma gas to close the small hole, the process method is not mastered properly, and welding defects such as incomplete penetration, air holes, burnthrough, poor forming and the like can be generated in a small hole closing tail area, so that the process becomes a key difficulty of the plasma girth welding process. Many factors such as materials, weldment structures, welding equipment, weldment heat dissipation conditions, welding environments and the like have great influence on the hole closing process specification, so that the problem of welding defects in the plasma circular seam ending region is a hot spot of controversial research by welding technicians. A universal plasma circular seam hole closing process method is found through a welding test, and the method is the most effective way for solving the problems.

Disclosure of Invention

The invention aims to solve the defects of the prior art and provide a plasma girth welding receiving hole process method, which solves the problems of incomplete welding, air holes, burning-through, poor forming and other welding defects of a small hole tail area of a plasma girth through the decreasing slope of three sections of different hole closing currents in welding process parameters and the attenuation of ion gas and wire feeding speed, and can ensure the quality requirement of a high-quality welding joint.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a plasma girth welding receiving hole process method comprises the following steps:

step (1), a circular seam starting section:

(1.1) the protective gas is supplied for 5-10 seconds in advance.

(1.2) starting the welding current, the ion gas and the weldment rotation at the same time, rising the welding current and the ion gas, perforating the weldment, forming a pinhole effect in a molten pool, and starting wire feeding;

(1.3) continuously increasing the welding current, the ion gas and the wire feeding speed to reach the normal welding current of 100-350A, the ion gas flow of 0.5-2.8 scfh and the wire feeding speed of 800-2800 mm/min, starting normal welding, and entering a welding section;

step (2), girth welding the section:

(2.1) the welding current of the normal welding section is in a slow-decreasing uniform-speed trend, the total decreasing amplitude of the current from the beginning of welding to the end of welding of the circular seam welding section is 5% -30%, and the current can be properly adjusted according to the actual circular seam length;

(2.2) the ion gas and the wire feeding speed are constant, and fine adjustment can be carried out according to the actual welding condition;

step (3), a circular seam ending section:

(3.1) ring seam tail closing area ascending section: the welding current rises at a constant speed, the total rising amplitude of the current is 5 to 30 percent after the welding is started from the rising section of the circular seam tail-closing area and the welding is finished, the ion gas is kept unchanged, and the wire feeding speed drops at a constant speed; the welding length of the ascending section of the circular seam tail closing area is 30-80 mm;

(3.2) circular seam tail closing area descending section: the welding current is reduced at a constant speed, and the total reduction amplitude of the current is 30 to 70 percent after the welding is started from the descending section of the circular seam tail-closing area to the end; the ion gas descends at a constant speed, the total descending amplitude of the ion gas is 50% -80% after the ion gas descends from the descending section of the circular seam tail closing area by welding, the wire feeding speed descends to zero at a constant speed, and the small hole closing of a molten pool is completed; the welding length of a descending section of the circular seam tail closing area is 60-120 mm;

(3.3) abrupt descending section of the circular seam ending region: the welding current drops to zero at a constant speed, the ion gas drops to zero at a constant speed, the welding receiving arc is completed, the rotation of the weldment is stopped, the gas supply is stopped after the shielding gas lags for at least 10 seconds, and the circular seam welding is finished; the welding length of the steep descending section of the circular seam tail closing area is 30-80 mm;

wherein, the wire feeding speed reduction speeds in the steps (3.1) and (3.2) are the same; and (3.2) and (3.3) the descending speed of the ion gas is the same.

The invention has no limit on the welding length of the circular seam starting section and the circular seam ending section, and can be adjusted according to the prior art and the actual situation.

Compared with the prior art, the invention has the beneficial effects that:

a) the method for reducing heat input by slowly reducing current at constant speed in the welding section effectively solves the problems of thick welding seam joint structure and poor appearance forming caused by accumulated heat input of the welding seam at the tail section in the existing standard with constant and unchangeable current, and the qualified rate of the welding seam appearance reaches 100 percent.

b) The existing specification of the circular seam ending section is that welding current and ion gas are reduced at constant speed, the invention adopts the method that the welding current is firstly increased and then reduced, and the ion gas is kept and is firstly maintained and then reduced, thus thoroughly solving the old and difficult problems that the back surface is badly formed and not welded because the circular seam arcing joint has high welding seam and is not melted completely. The qualification rate of X-ray flaw detection of the welding seam and the qualification rate of appearance of the front side and the back side reach 100 percent.

The invention successfully solves the technical problem of plasma girth welding hole receiving, avoids the welding defects of incomplete penetration, air holes, burning-through, poor forming and the like in the girth ending area, can ensure the high-quality requirement of a girth welding joint, and obtains very good application effect.

Drawings

FIG. 1 is a schematic view of a plasma girth welding current routine of the present invention;

FIG. 2 is a schematic view of a plasma gas process for plasma girth welding according to the present invention;

FIG. 3 is a schematic diagram of a wire feed speed process for plasma girth welding according to the present invention.

Detailed Description

The present invention will be described in further detail with reference to examples.

It will be appreciated by those skilled in the art that the following examples are illustrative of the invention only and should not be taken as limiting the scope of the invention. The examples do not specify particular techniques or conditions, and are performed according to the techniques or conditions described in the literature in the art or according to the product specifications. The materials or equipment used are not indicated by manufacturers, and all are conventional products available by purchase.