RU2399467C1 - Machine for butt-seam flash welding and further thermal treatment of strips - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to welding engineering, namely to devices for contact butt-seam flash welding and further thermal treatment of strips that operate in continuous metallurgical plants, for instance in etching lines or longitudinal cutting plants, processing mainly high-carbon steel strips. Machine comprises fixed and movable bed plates with clamps having upper and lower grips, welding transformer with current contact jaw to lower pressing grips and closed system of lower pressing grips cooling. Cooling system consists of grips arranged on two lateral sides for supply and drain longitudinal channels connected to each other at each side by three transverse channels with pressure controllers and valve of cooling liquid supply. Second and third transverse channels comprises controllers of longitudinal supply channels length, arranged in the form of stop needles.

EFFECT: simplified design of machine and improved quality of welding joint due to its even heating along length in process of thermal treatment.

2 dwg

Description

The invention relates to welding production, and in particular to devices for flash butt welding of strips operating in continuous metallurgical units, for example, in pickling lines or slitting units, processing mainly strips of high carbon steels.

The welded joints of strips of high carbon steels, due to high cooling rates after welding, are intensively hardened, become brittle and unsuitable for transportation through the unit, and often collapse immediately at the exit of the welding machine. Therefore, in welding machines, heat treatment of welded joints is provided immediately after welding, directly in the lips of the welding machine, by heating with current from the welding transformer. However, due to the irregular cross-section of the strips (for example, concavity obtained during hot rolling), as well as due to the displacement of the passing current to the edges of the strips, the side edges of the joints overheat upon heating and their quality after heat treatment is uneven in length.

A known machine for butt welding of the ends of the strip reflow / ed. testimonial. SU No. 1152746 A1, MKI V23K 11/04, 04/30/1985 /, containing a welding transformer, beds with clamping jaws placed in them, having electrodes mounted with busbars, equipped with busbars, and also equipped with current-distributing inserts of electrically conductive material installed between electrodes and busbars made in the form of comb plates or trapezoidal plates.

The disadvantage of such a machine is that current-distributing plates limit the flow of current not only during heat treatment, but also during welding, since both during welding and during heat treatment the strips are clamped by the same electrodes under which the current supply limiting length along the plate junction is constantly installed, therefore, the edges of the joints during reflow may not be sufficiently heated and not prepared for sediment. The trapezoidal inserts installed under the base lower electrodes, with the upper clamping of the strips, can lead to a displacement in the extreme sections of the joints in height during upsetting, since from the edges the electrodes have no support when clamped.

A known method of heating strips with a weld during heat treatment in the electrodes of a butt welding machine / ed. testimonial. SU No. 1266689 A1, MKI V23K 11/02, 11/04, 30X1986 /, in which an electric current is passed through the weld zone, and the specific clamping pressure of the strips in the electrodes of the welding machine is reduced by 1.5 ... 2, along the length of the weld 0 times from its middle to the edges.

The disadvantage of this method is that for its implementation it is required to have at least three clamping cylinders arranged along the width of the strips in the welding machine on each bed, since the pressure of clamping the strips is reduced by reducing the pressure in the extreme cylinders. On middle-class machines for welding strips up to 800 mm wide with one or two clamping cylinders this method is not applicable.

The closest to the proposed invention by technical nature and the achieved result is a device for automatic welding and subsequent heat treatment of welds described in SU No. 1269945 A2, IPC V23K 11/04, 11/24, 11/15/1986, containing a fixed and movable frame with clamps equipped with upper and lower clamping jaws, a welding transformer with contact current supply to the lower jaws, into which temperature meters, comparison units, relays, valves for supplying a cooling medium (for example, compressed air) are required seam portion along the edges.

The main disadvantage of this method is the need to provide reliable protection of optical non-contact temperature sensors from particles of molten metal during welding by continuous fusion or to create a complex system for introducing sensors into the space between the beds after welding and removing them after heat treatment, while losing control of the joint temperature at the time of sensor input and the overall system performance is reduced. In addition, when changing the width of the welded strips, it is necessary to adjust the extreme sensors and the coolant supply system.

The technical result of the proposed solution is to improve the quality of the welded joint by ensuring uniform heating of the welded joint along the length during heat treatment while simplifying the design of the machine.

The technical result with the achievement of the above effect is ensured by the fact that the machine for butt welding of strips of fusion, containing a fixed and movable bed with clamps equipped with upper and lower clamping jaws, a welding transformer with contact current supply to the lower clamping jaws, is equipped with a closed cooling system of the lower clamping jaws, consisting of sponges of inlet and outlet longitudinal channels made on two sides of the lips, interconnected on each side by three transverse channels and with pressure regulators and a coolant supply valve, while in the second and third transverse channels, length regulators of the longitudinal supply channels are made in the form of locking needles.

The inventive machine for butt welding of fusion strips is illustrated by drawings, where

- figure 1 schematically shows the inventive butt welding machine (with a cut along the axis) and a strip passing through it;

- figure 2 schematically shows a top view of a current-carrying sponge with a cut along the longitudinal and transverse cooling channels.

The machine for butt fusion of strips contains a fixed 1 and a movable 2 bed with clamps 3 and 4, equipped with upper 5 and lower 6 clamping jaws, a welding transformer 7 with contact current supply 8 to the lower clamping jaws 6, a cooling system for jaws 9 of a closed cycle with pressure regulators 10 and the coolant supply valve 11. The two lower current-carrying jaws 6 have inlet 12 and outlet 13 longitudinal channels for coolant on two sides, which are interconnected by transverse channels 14. Transverse e channels are made with the installation of length regulators of the longitudinal supply channels 12 in the form of locking needles 15, while length regulators are installed in the second and third transverse channels 14 on each of the sides of the jaw 6.

Machine for flash butt welding of strips works as follows.

After welding the strips, clamps 3 and 4 are lifted together with the upper clamping jaws 5 and the movable bed 2 is withdrawn to the distance necessary for heating during heat treatment. Then, clamps 3 and 4 are lowered and the strips are pressed to the lower current-carrying jaws 6. These operations are carried out on the machine in automatic mode at the highest possible speed to maintain the joint heating obtained during reflow, then turn on the coolant supply valve 11 and, at the same time, the welding transformer 7, and in this case, the electric current from the welding transformer through current leads 8 and lower current-carrying jaws 6 is supplied to the welded strips and then passes through the joint, heating it along its entire length. The heated metal of the joint has an increased electrical resistance and therefore quickly heats up, and due to heat transfer, the bands adjacent to the joint are also heated. However, due to the effect of crowding out the passing current at the edges of the strips, the extreme sections of the joint overheat, the current-carrying lower lips 6 cooled from the sides, due to the intensive heat removal, prevent overheating and promote uniform heating of the joint along the length. After passing the heating cycle and delayed cooling, the welding transformer is turned off, the coolant supply is turned off and clamps 3 and 4 are lifted, and the movable bed 2 is returned to its original position before welding. After switching to welding strips of a different width or thickness when heating the first joint, the temperature of the edge sections is visually controlled and, if necessary, the length of the longitudinal channel supplying the cooling medium to the channel 12 is adjusted by locking the transverse holes with needles 15, thereby cutting off the supply of coolant through the transverse channels to the sections of the longitudinal channels, closest to the middle of the jaws 6. In this case, the maximum heat removal is carried out from the edges of the strips and decreases towards the center, which correlates with the real unevenness of heating, since narrower bands this unevenness is lower. The presence of locking needles 15 in the transverse channels 14 also eliminates uneven heating on both sides of the strip caused by the unilateral arrangement of the transformer, as it makes it possible to reduce the forced cooling of the jaws 6 on either side, thereby avoiding excessive energy losses.

Thus, the proposed adjustable cooling of the lateral edges of the clamping jaws along the length of the longitudinal supply channels allows them to be used for welding and heat treatment of the entire range of strip widths, as well as for single and double-sided arrangement of current leads and transformers.

Thus, the proposed machine for butt welding of fusion strips, comprising a fixed and movable bed with clamps equipped with upper and lower clamping jaws, a welding transformer with contact current supply to the lower clamping jaws, and also equipped with a closed jaw cooling system, including transverse and interconnected longitudinal channels, with pressure regulators and a coolant supply valve, in each transverse channel, except for the extremes on both sides of the jaws, length length regulators are installed ial supply channels made in the form of locking needles, you can:

- improve the quality of the weld by ensuring uniform heating of the weld along the length when re-heated in a heat treatment cycle and controlled cooling;

- abandon two edge temperature meters and thereby simplify the design of the machine;

- it is most effective to use such welding machines in units for processing strips of high-carbon and alloy steels, the welded joints of which after welding and rapid cooling in air are hardened and become unsuitable for transportation and processing in the line.

Claims (1)

A machine for flash butt welding and subsequent heat treatment of strips, comprising a fixed and movable bed with clamps provided with upper and lower clamping jaws, a welding transformer with contact current supply to the lower clamping jaws, characterized in that it is equipped with a closed cooling system of the lower clamping jaws, consisting of made from two sides of the lips of the inlet and outlet longitudinal channels, interconnected on each side by three transverse channels with pressure regulators and to apani coolant, while the second and third set of transverse ducts regulators length of the longitudinal feeding channels formed in the form of a latch needle.

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