RU2510315C1 - Method of butt fusion welding - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention can be used for but fusion welding of parts from similar or difference materials. Shim is arranged between faces of parts and has cross-section area S_{f p}. Shim material is selected with allowance for part material liquidus temperature T°_l. Cross-section area of shim part in contact with welded parts is smaller than that of remaining part. End faces of parts are heated by shim current while parts are upset in two steps. Preliminary upsetting is performed by not over 0.5 mm for every part at the temperature of end faces of parts T°_{f p}=0.8 T°_l. Said part material liquidus temperature reached, final upsetting is performed by force P_up=0.9σ_0.2·S_{f p}.

EFFECT: simplified welding, reliable seam at minimised heating influence on part structure.

3 cl, 3 dwg

Description

The invention relates to the field of welding production and can be used in butt welding processes by fusion of parts from the same or different materials.

There is a known method of butt welding, in which current leads connected to a current source are fixed on the parts being welded, the ends of the parts to be welded are brought into contact, which are then heated to a certain temperature by passing current through the parts, after which the parts are precipitated and then cooled to obtain a welded joint ( JP 56-165568, B23K 11/24, 1981).

The disadvantage of this method is to change the structure of the parts to be welded, since when the welding current passes through them, in addition to the ends of the parts, the parts themselves undergo significant heating. In addition, with this method, welding of parts from various materials is very problematic.

There is a known method of joining by welding dissimilar elements, in which an intermediate gasket of the corresponding material is used, which is first welded to one of the elements to be joined, and then another element is welded here, after which heat treatment is carried out by diffusion annealing (EP 0467881, B23K 11/20, 1992) .

The disadvantage of this method is the complexity of the welding process.

There is also known a method of butt welding by continuous melting, adopted as a prototype, which consists in placing the parts to be welded in the clamps of the welding machine, installing current leads on the parts, bringing the parts in contact with each other and turning on the welding machine according to the established program for changing the welding current parameters , reflow and precipitation. When the ends of the parts are melted and the set temperature is reached on them, the parts are settled by the required amount, then the welded parts are cooled (SU 737156, V23K 11/04, 1980).

The disadvantages of the prototype are the same as those listed above for the above analogues.

The objective of the invention is to obtain a reliable welded joint while minimizing the influence of the welding process on the structure of parts, which can be from the same or different materials, as well as simplifying the welding process.

The solution to this problem is achieved by the fact that in the flash butt welding method, which includes heating the ends of the parts to be welded using electric current until they are fused, the parts are upset to the required amount when the specified temperature is reached at the ends of the parts and subsequent cooling of the parts, welding of parts made from one or different materials, carried out in a protective gas environment, and between the ends of the parts place a gasket made of a material with a liquidus temperature:

T ⁰ _{l prokl.} ≥T ⁰ _{L children max} + 100 ° C,

where T ⁰ _{l prokl.} - liquidus temperature of the gasket material,

T ⁰ _{l det max} - the liquidus temperature of the material of the parts or the maximum of the two, if the material of the parts is different,

The cross-sectional area of that part of the gasket that is not in contact with the parts to be welded is larger than the cross-sectional area of that part of the gasket that is in contact with the parts. The end faces of the parts are heated by bringing them into contact with the gasket and passing current through it, and the parts are upset in two stages - first, preliminary upsetting by a value of not more than 0.5 mm for each part when the end temperature of the parts reaches T ⁰ _end = 0, 8 T ⁰ _{l children max} , and then, when the temperature of the part of the gasket that is in contact with the welded parts is reached, the liquidus temperature of the gasket material is the final draft with a force F _ocad = 0.9 σ _0.2max S _{end face} ,

where σ _0,2max is the conditional yield strength of the material of the parts (the maximum of the two, if the material of the parts is different),

S _{butt face} - the area of the _butt ends of the parts,

until a burr is formed, which is then removed mechanically after the parts have completely cooled.

The invention is illustrated by drawings, where:

figure 1 shows a diagram of the implementation of welding;

figure 2 shows the gasket placed between the parts;

figure 3 shows the resulting welded joint parts.

The method is as follows.

The parts to be welded 1 are placed in an appropriate device that provides the necessary details for the parts (conditionally not shown). Between the parts 1, which can be made from one or from different materials, a gasket 2 is installed. The material of the gasket 2 is selected from the condition:

T ⁰ _{l prokl.} ≥T ⁰ _{L children max} + 100 ° C,

where T ⁰ _{l prokl.} - liquidus temperature of the gasket material, I

T ⁰ _{l det max} - the liquidus temperature of the material of the parts or the maximum of the two, if the material of the parts is different.

Moreover, the cross-sectional area of that part of the gasket 2 that is not in contact with the parts to be welded 1 is larger than the cross-sectional area of that part of the gasket that is in contact with the parts. This is necessary to concentrate the heating of the strip while passing an electric current through it in the area of the ends of the parts, since the heating of the conductor is inversely proportional to its cross-sectional area. After that, the ends of the parts 1 are brought into contact with the gasket 2, through which a current is passed, for which special current leads 3 are made along its outer edges, for example, from copper. In this case, the gasket 2 is heated and, accordingly, the ends of the parts 1 are heated. The welding process is conducted in a shielding gas environment. The heating process when passing current through the gasket can be performed according to a given program (for example, by appropriate changes in current parameters). When the temperature of the ends of the parts T ⁰ _end = 0.8 T ⁰ _{l children max} , a preliminary settlement of the parts 1 is carried out by an amount of not more than 0.5 mm for each part, while the ends of the parts are embedded into the gasket by the specified value, which contributes to the intensification of the further process heating and melting the ends of the parts. Further, when the temperature of the portion of the napkin 2, which is in contact with the welded parts 1, the liquidus temperature of the gasket material produce final parts with precipitate force F _siege = 0,9 σ _0,2max S _{facer children,}

where σ _0,2max is the conditional yield strength of the material of the parts (the maximum of the two, if the material of the parts is different),

S _{butt face} - the area of the _butt ends of the parts.

In the process of final precipitation, molten gasket material is squeezed between the ends of the parts 1, which are in the molten state and are pressed together to form a burr 4, which is then removed mechanically after the parts have completely cooled. Temperature control during the welding process can be carried out, for example, using a thermal imager.

In order to obtain a high-quality welded joint in case the material of the molten gasket partially remains between the parts after the final settlement and mixes with their material, it is desirable to select the gasket material, in addition to the above conditions, with the possibility of formation of solid solutions of the material of the parts and gasket material during welding.

The proposed method allows to simplify the process of flash butt welding and to obtain a reliable welded joint while minimizing the influence of the welding process on the structure of parts.

Claims (3)

1. The method of butt welding of parts by reflow, including heating their ends with electric current before reflowing, depositing the parts by the required amount when the specified temperature is reached at the ends of the parts and cooling the parts, followed by removal of the weld, characterized in that the welding is carried out in a protective gas environment, at the same time, a gasket is placed between the ends of the parts, the cross-sectional area of the part of which in contact with the parts being welded is less than the cross-sectional area of the rest, and the material l which is selected from the condition:
T ° _{l procl.} ≥T ° _{L det} + 100 ° C,
where T ° _{l procl.} - liquidus temperature of the gasket material,
T ° _{l det} - the liquidus temperature of the material of one of the parts,
the heating of the ends of the parts to be welded is carried out after bringing them into contact with the gasket by passing current through it, and the parts are precipitated in two stages, and first, preliminary precipitation is carried out by no more than 0.5 mm for each part when the temperature of the ends of the parts T ° _{end face} = 0.8 T ° _{L det} , and then, when the part of the gasket in contact with the welded parts reaches the liquidus temperature of its material, the final _settlement is performed with a force F _ocad = 0.9σ _0.2 · S _{end face} ,
where σ _0,2 is the conditional yield strength of the material of one of the parts,
S _{butt face} - the area of the _butt ends of the parts. 2. The method according to claim 1, characterized in that the gasket material is selected from the conditions of formation with the materials of the parts after welding of solid solutions. 3. The method according to claim 1, characterized in that when welding parts made of different materials, choose T ° _{L det} corresponding to the maximum liquidus temperature of the material of one of the parts, and σ _0.2 - corresponding to the maximum conditional yield strength of the material of one of details.

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