RU2570270C2 - Method of electron beam welding of nonmagnetic metals and alloys - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to machine building, particularly, to electron beam welding. Claimed process comprises part-through penetration of the parts (4) butt (3) by electron beam (2) and induction of constant magnetic field inside welding parts of maximum magnitude in the weld root. Beam (2) and penetration channel tip (11) are deflected along the butt or in opposite direction.

EFFECT: higher quality of nonmagnetic metals and alloys welds, enhanced performances.

4 dwg, 1 ex

Description

The invention relates to the field of engineering, in particular to a method for electron beam welding of non-magnetic metals and alloys in vacuum. It can be used in various branches of mechanical engineering when performing critical welded joints.

The prototype selected the closest in technical essence to the proposed invention the method of electron beam welding of non-magnetic metals and alloys described in the patent of the Russian Federation No. 2433024, B23K 15/00, B23K 28/02, published November 10, 2011. This patent proposes electronic penetration of the joint beam, the creation of an alternating magnetic field inside the parts to be welded and the formation of a given geometry of the electron beam and the penetration channel by deflecting the electron beam perpendicular to the junction plane.

The same result is achieved by the welding method described in RF patent No. 2433023, B23K 15/00, B23K 28/02, published November 10, 2011, where, in contrast to the above patent, it is proposed to create a magnetic field deflecting the electron beam across to the seam plane, conducting electric current directly through the welded parts. Electric current is connected to the parts to be welded using special current leads.

Another welding method is known from RF patent No. 2346795, B23K 15/00, published on February 20, 2009, in which the deflection of the melt channel perpendicular to the butt plane when welding parts of dissimilar metals and alloys is compensated by a local magnetic field created by a set of coils through which electric current is passed. This method allows you to weld the joint of the welded parts, having an arched shape.

All of these patents create a local magnetic field directed parallel to the joint plane of the welded parts in the direction of movement of the seam or in the opposite direction. In this case, the deflection of the melt channel occurs in a direction perpendicular to the plane of the junction of the welded parts.

An object of the present invention is to improve the quality of a deep weld in a non-through penetration by improving the formation of the root part of the seam and expanding the technological capabilities of electron beam welding. The solution to this problem is achieved by deflecting the electron beam in the seam root zone, the focus of which is located inside the welded part, and the beam focus position along the thickness of the welded part is kept constant.

Unlike the prototype, the deflection of the melt channel in the weld root area is made in the joint plane in the direction of the weld movement or in the opposite direction with a local magnetic field directed perpendicular to the joint plane of the parts to be welded.

During deep penetration by an electron beam, the end of the penetration channel in the zone of the weld root converges conically to a point, forming a tip, where the most intense formation of metal vapor and metal melting take place. These highly unsteady processes cause fluctuations in the depth of penetration, which causes the formation of so-called spice and weld defects, causing a decrease in the quality of the weld.

The method of electron beam welding consists in the fact that a non-uniform local magnetic field created in the weld root area, perpendicular to the joint plane, deflects the tip at the end of the melt channel in the joint plane of the welded parts in the direction of weld movement or in the opposite direction, deflecting the tip from the weld root channel penetration, which improves the formation of the root of the seam. Moreover, to obtain the same penetration depth as when welding without a magnetic field, increase the welding current.

The invention is shown in figure 1, figure 2, figure 3 and figure 4.

The electron-optical column 1 forms a narrowly focused electron beam 2, which is directed to the joint 3 of the welded parts 4. An inhomogeneous constant local magnetic field B is created in the region of the weld root with magnet 5, perpendicular to the joint 3. The absolute value of the magnetic field as it approaches the entrance side joint 3 of the electron beam 2 to the root of the seam increases. Welded parts 4 move the movement mechanism 6.

As shown in FIG. 2, magnet 5 consists of magnetic cores 7 and 8 made of a soft magnetic ferromagnet and a permanent magnet 9 of a hard alloy based on rare earth elements. Magnet 5 can be replaced by an electromagnet, where instead of a permanent magnet, a solenoid with a core made of a soft magnetic ferromagnet is placed. In this case, the magnitude of the local magnetic field and its direction can be changed.

и индукции магнитного поля B (фиг.1). В нашем случае $$V_e^{-}$$

и B перпендикулярны друг другу, поэтому абсолютная величина силы Лоренца:As is known, the Lorentz force proportional to the electron charge and the vector product of the electron velocity acts on an electron moving in a magnetic field $$V_e^{-}$$

and magnetic field induction B (FIG. 1). In our case $$V_e^{-}$$

and B are perpendicular to each other, therefore the absolute value of the Lorentz force:

, где $$I_e^{-}$$

- ток электронного луча (фиг.2). $$\left|F\right|=\left|I_e^{-}\right|\times \left|B\right|$$

where $$I_e^{-}$$

- current of the electron beam (figure 2).

, то отогнутый большой палец покажет направление силы Лоренца, то есть направление отклонения электронного луча и вместе с ним направление отклонения канала 11 проплавления стыка.The direction of the Lorentz force is determined by the rule of the left hand - if the palm of the left hand is placed so that B is directed to the open hand, and the four fingers extended are directed in the direction $$I_e^{-}$$

, then the bent thumb will show the direction of the Lorentz force, that is, the direction of deviation of the electron beam and with it the direction of deviation of the joint penetration channel 11.

Example. Samples of stainless steel 12X18H10T with a thickness of 10 mm were welded by electron beam welding in two different modes. In the first mode: U = 60 kV, I = 70 mA, V _St. = 10 ^-2 m / s, where V _St. - welding speed, and without a constant magnetic field; in the second mode, the same parameters, but in the initial section of the weld, the welding proceeds without a constant magnetic field, and in the second half of the length of the weld, a constant magnetic field of several kilos Oersted is created in the zone of the root of the weld transverse to the joint.

The produced longitudinal macro sections showed that when welding without a magnetic field, the depth of the penetration channel 10 sharply fluctuates, forming a serrated root structure of the weld, and when welding with a magnetic field there are no sharp depth fluctuations (gear structure). In the first case, the average penetration depth is 8 mm, and in the second case, with an increase in the magnetic field, the penetration depth decreases from 8 mm to 5 mm. If the beam is deflected in the direction of the seam movement, then the seam ends with a tip protruding towards the deflection of the beam in a depth of 4 mm, if the beam is deflected against the course of the seam, then the seam ends with rounding. On the thin sections it can be seen that the desired effect can be achieved with lower values of the magnetic field, while an increase in the penetration depth with a decrease in the magnetic field is observed. This shows that to achieve the same penetration depth as when welding without a magnetic field, increase the welding current.

Claims (1)

A method of electron beam welding of non-magnetic metals and alloys, including through penetration of the junction of the parts to be welded by an electron beam, the focus of which is located inside the part to be welded, and the creation of a local constant magnetic field inside the parts to be welded, the magnitude of which increases with approaching the weld root zone, characterized in that the point of the penetration channel in the weld root zone is deflected by a magnetic field in the junction plane, while the magnetic field is created by a constant Ithomi while moving the workpiece.

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