RU2522670C2 - Electron-beam welding - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to electron-beam welding. Proposed method comprises applying of local magnetic field to parts butt, directing of electron beam to said butt to form penetration channel and electron-beam welding of parts at bottom position with part-through penetration. Applied is magnetic field its direction being perpendicular to butt plane. Electron beam is directed at acute angle to the interface selected to make electron beam enter the penetration channel at 90°±15°, to form beam curvilinear path and to direct electron beam nearby penetration channel bottom at 0÷30°.

EFFECT: higher quality of weld joint.

1 dwg

Description

The invention relates to the field of engineering, in particular to a welding method, and may find application in the production of various welded structures for critical purposes.

A known method of welding with an electron beam in the lower position (Mamutov E.L., Electron beam welding of large thickness parts, Moscow, Mashinostroyenie, 1992, 125 pp.) Comprising an electron beam gun, welded parts, an electron beam, a weld pool, a penetration channel and weld. However, during deep-penetration electron beam welding, the beam is periodically shielded by metal vapors and the moving liquid metal of the weld pool, which leads to periodic beam defocusing and the instability of the electron beam at the melting front and at the root of the seam.

However, with this welding method, root defects are formed, such as inconsistencies in the penetration depth, the presence of cavities and non-fusion in the root peaks, which leads to a decrease in the quality of welded joints.

There is a welding method in which the joint of the welded parts is simultaneously melted by an electron beam and an arc discharge coaxially located with it, which is formed by a hollow cathode. The electron beam is directed from the front side of the junction through the plasma of the arc discharge and create a magnetic field of the arc discharge in the same direction with the magnetic field of the electron beam, forming the desired geometry of the electron beam and the penetration channel into which the arc discharge energy is supplied, and the electron beam is rejected by the thickness of the parts in the required direction by a given value (RF patent No. 2174067, IPC B23K 15/00).

The disadvantage of this method is the significant complication of the equipment due to the introduction of a hollow cathode into the welding area, in addition, the magnetic field of the arc discharge currents spreading over the part is not enough for a significant deviation of the electron beam.

Closest to the technical nature of the present invention is a method of electron beam welding in the lower position, including the formation of a plane of the welded joint, the application of a local magnetic field to at least part of the welded joint, and this magnetic field is perpendicular to the axis of the electron beam, and parallel to the plane of the welded joint of parts, the direction of the electron beam to the welded joint for electron beam welding of parts, and obtaining a welded joint. Moreover, the specified local magnetic field controls the electron beam as it passes through the interface (RF patent No. 2346795, IPC B23K 15/00).

However, in this method, the main thing is to solve the problem of the curvature of the electron beam at the bottom of the weld in the direction of one of the parts when welding dissimilar metals. In this case, a decrease in the quality of welded joints due to the formation of root defects.

An object of the invention is to improve the quality of welded joints.

The technical result consists in reducing root defects that arise due to fluctuations in the depth of penetration during electron beam welding without through penetration in the lower position and is achieved by the fact that in the known method, including the formation of the joint plane of the parts to be welded, application of a local magnetic field to the part of the welded joint, perpendicular to the axis of the electron beam, the direction of the electron beam to the joint for electron beam welding of parts, welding is carried out in the lower position with a straight through phenomenon, and the lines of the magnetic field directed perpendicular to the joint plane, the electron beam is directed at an acute angle to the surface of the welded components.

The invention is illustrated by a diagram that implements a welding method. The scheme for implementing the method comprises an electron beam gun 1, welded parts 2, an electron beam 3, a mechanism for moving parts 4, table 5, a weld pool 6, a penetration channel 7, a weld 8.

The essence of the ELS method is as follows.

, движущаяся в магнитном поле $$\overrightarrow{B}$$

, испытывает воздействие силы $$\overrightarrow{\text{F}}$$

, называемой силой Лоренца. Эта сила действует перпендикулярно векторам $$\overrightarrow{\text{B}}$$

и $$\overrightarrow{\text{v}}$$

. Величина и направление этой силы определяются векторным произведением $$\overrightarrow{F}=q=\left[\overrightarrow{v},\overrightarrow{B}\right]$$

. Данная сила задает траекторию движения электронов луча по дуге окружности. Периодическое экранирование луча парами металла и перемещающимся жидким металлом сварной ванны, не будут оказывать существенного влияния на макроструктуру сварного шва, а именно - на образование пиков проплавления в корне шва, так как вблизи дна канала проплавления электронный луч будет находиться под углом γ=(0…30°) относительно направления сварки. Основополагающим является отклонение луча в локально именно в корне шва для уменьшения амплитуды возникающих в процессе сварки корневых швов. Величина начального наклона электроннолучевой пушки α зависит от расстояния между пушкой и поверхностью свариваемых деталей, распределения индукции магнитного поля и выбирается таким образом, чтобы электронный пучок входил в канал проплавления под углом $$\beta =\left({90}^{\circ }\mp {15}^{\circ }\right)$$

относительно лицевой плоскости свариваемых деталей, что сократит длину пути электронного луча в канале проплавления, и, соответственно, потери энергии пучка электронов, вызванные его рассеиванием парами металлов.They create a magnetic field whose induction lines are directed perpendicular to the electron beam and the plane of the welded joint and pass through the welded joint of the parts. The welding process is carried out in a vertical beam in the lower position with a through penetration. Under the vertical beam welding in the lower position, it is generally accepted to understand that the penetration depth is combined with the depth of the weld pool (direction of gravity); under welding with a horizontal beam on a vertical wall - the depth of the weld pool (direction of gravity) is combined with the width of the seam (horizontal seam). It is known that a particle with charge q and velocity $$\overrightarrow{\text{v}}$$

moving in a magnetic field $$\overrightarrow{B}$$

experiencing force $$\overrightarrow{\text{F}}$$

called the Lorentz force. This force acts perpendicular to the vectors $$\overrightarrow{\text{B}}$$

and $$\overrightarrow{\text{v}}$$

. The magnitude and direction of this force are determined by the vector product $$\overrightarrow{F}=q=\left[\overrightarrow{v},\overrightarrow{B}\right]$$

. This force sets the trajectory of the electron beam along the arc of a circle. Periodic screening of the beam by metal vapor and the moving liquid metal of the weld pool will not have a significant effect on the macrostructure of the weld, namely, on the formation of penetration peaks in the root of the weld, since the electron beam will be at an angle γ = (0 ... near the bottom of the penetration channel 30 °) relative to the direction of welding. It is fundamental that the beam is deflected locally precisely at the root of the seam to reduce the amplitude of root welds arising during welding. The initial slope of the electron beam gun α depends on the distance between the gun and the surface of the parts to be welded, the distribution of the magnetic field induction, and is chosen so that the electron beam enters the penetration channel at an angle $$\beta =\left({90}^{\circ }\mp {\mathrm{fifteen}}^{\circ }\right)$$

relative to the front plane of the welded parts, which will reduce the path length of the electron beam in the penetration channel, and, accordingly, the energy loss of the electron beam caused by its scattering by metal vapor.

The rotation angle of the velocity vector of an electron moving in a uniform magnetic field acting within the welded joint perpendicular to its plane is determined by the following expression:

, $$tg\left(\gamma \right)=\mathrm{one}-\frac{eB}{m}tg\left(\alpha \right)t$$

,

where e is the electron charge, B is the induction of the magnetic field, m is the mass of the electron, t is the time the electron moves from the surface of the product to the bottom of the channel.

относительно лицевой плоскости свариваемых деталей, причем электроны имеют криволинейную траекторию по всему своему пути. Затем, посредством механизма перемещения 4, перемещают стол 5 с расположенными на нем свариваемыми деталями 2 со скоростью сварки и проводят сварку без сквозного проплавления свариваемых деталей. В результате расплавления основного металла свариваемых деталей 2 образуется общая сварочная ванна 6, окружающая криволинейный канал проплавления 7, которая затем кристаллизуется с образованием сварного шва 8. Величина индукции магнитного поля выбирается исходя из требуемой глубины проплавления, ускоряющего напряжения электроннолучевой пушки и угла наклона электроннолучевой пушки к плоскости свариваемых деталей.The scheme for implementing the ELS method works as follows. They create a magnetic field whose induction lines are perpendicular to the edges to be welded. The electron beam gun 1 is installed vertically at an angle α to the front plane of the welded parts 2, selected from the condition 0 ° <α <90 °. The electron beam 3 from the electron gun 1 directs the welded joint 2 so that the beam entered the penetration channel at an angle $$\beta =\left({90}^{\circ }\mp {\mathrm{fifteen}}^{\circ }\right)$$

relative to the front plane of the parts to be welded, and the electrons have a curved path along their entire path. Then, by means of the moving mechanism 4, the table 5 is moved with the welded parts 2 located on it with a welding speed and welding is performed without through penetration of the welded parts. As a result of the melting of the base metal of the parts to be welded 2, a common weld pool 6 is formed, surrounding the curvilinear penetration channel 7, which then crystallizes to form a weld 8. The magnitude of the magnetic field induction is selected based on the required penetration depth, accelerating voltage of the electron beam gun and the angle of inclination of the electron beam gun to the plane of the welded parts.

Using the proposed welding method provides welded joints without the formation of root defects such as penetration peaks, instability of the penetration depth.

Claims (1)

A method of electron beam welding of parts, including applying a local magnetic field to the junction plane of the parts to be welded, directing the electron beam to the joint with the formation of a penetration channel and electron beam welding of parts in the lower position, characterized in that the welding is carried out without penetration, while applying a magnetic field, direction which is perpendicular to the joint plane, and the electron beam is directed at an acute angle to the surface of the welded parts, which is chosen from the condition of providing of the electron beam in the entrance channel penetration at 90 ° ± 15 °, formation of the curved beam path and ensure the electron beam direction near the bottom of the channel at an angle of penetration of 0 ÷ 30 °.