GB1584651A - Fabrication of cored welding wire - Google Patents

Description

(54) FABRICATION OF CORED WELDING (71) We, ACRES REUNES DE BUR BACH-EICH-DUDELANGE S.A., ARBED, of Avenue de la Liberte, Luxembourg, a society anonyme organised under the laws of Luxembourg, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention concerns the production of cored welding wires, i.e. welding wires having a metal sheathing enclosing a core of powder. Such wires can for example be used for the automatic or semi-automatic welding of metal pieces by arc with or without shield gas or under flux.

Known cored welding wires generally have a cylindrical exterior sheathing of steel, alloyed or not, of a diameter between 0.5 and 4 mm.

The core of powder is of mineral or metal products such as, most importantly, slag, fluxes, deoxidants, denitrants and/or alloys, and its quantity generally varies between 10 and 70% of the total weight of the welding wire. Ready for use these cored wires are wound on spools holding lengths of about 100 m.

Our U.K. Patent Specification No. 1,485, 571 describes and claims a process of manufacturing a welding wire having a core of powder and a tubular metallic member enclosing the core, the process including forming from a metal band an open channel having a pair of lateral flanks with upper end edges extending longitudinally of the channel, partially filling the channel over its length with the powder, cover the powder in the channel with a strip which extends partially around the powder and holds it at the bottom of the channel to keep it away from the said upper end edges of said flanks, closing the channel by bringing said end edges into abutment with each other, and welding the said upper end edges to each other. The cored welding wires thus obtained are of circular section.

The present invention provides a process of manufacturing a welding wire having a core of powder and a tubular metallic member enclosing the core, the process including forming from a metal band an open channel having a pair of lateral flanks with upper end edges extending longitudinally of the channel, partially filling the channel over its length with tin powder, covering the powder in the channel over at least a portion of its length with a strip which extends partially around the powder and holds it at the bottom of the channel to keep it away from the said upper end edges of said flanks, closing the channel by bringing said end edges into abutment with each other and welding them to each other, and working the result.

ing preform to a cored wire of a cross-section having a width greater than its thickness, (e.g.

an oblong), e.g. by drawing and/or flattening.

The preform may first be drawn to yield a wire of substantially circular or oval section am the latter flattened to yield the finished cored wire of oblong section.

The apparatus illustrated in U.K. Patent Specification No. 1,485,571 is suitable for carrying out the method according to the present invention, provided that the shaping roller and the dies are adapted or added to, as need arises.

The preform initially formed in accordance with the invention has a watertight envelope whose thickness and rigidity can be uniform over its whole circumference. It thus follows that the reduction in diameter and profiling of the preform can be carried out without difficulty and that it is possible to obtain finished cored wires in which the ratio of the width to the thickness is very high, e.g. at least 5, while the thickness can be very low but preferably at least 0.3 mm, e.g. 0.5 mm.

Moreover, as the wall thickness of these preforms can be varied between some tenths of millimetres and several millimetres, it is possible to produce cored flat wires in which the ratio of weight of powder to weight of the envelope can be very high or very low according to requirements. The core, uniformly distributed across the profile, is formed of mineral or metallic powders which are in particular slags, fluxes deoxidants, denitrants or alloys.

The amount of powder enclosed in the envelope is usually between 10 or 20% and 70% of the total weight of the cored wire and it is uniformly distributed along the length of the wire. The composition of the powder and that of the metallic envelope are chosen in known manner according to the uses and performances of the filled wires to be produced.

The cored wires are watertight when produced and they remain so during subsequent treatments. Also they can be rolled up, unrolled, treated in gaseous or liquid media and stored without fear of alteration or contamination of the powder core. The envelope of these cored wires can be given a metallic coating, e.g.

of copper.

The cored flat wires produced in accordance with the invention are particularly well suited to the preparation of wide welds in the processes of assembling with or without support, or replenishing and coating metal pieces by arc welding with or without protective gas or with flux.

Cored wires produced in accordance with the invention are particularly well suited for replenishing and coating pieces with nonoxidisable steels, steels resistant to wear and to impact, martensitic chromium steels, austenitic manganese steels, chromium-manganese tempering steels and high-speed steels.

The following is one example of the method according to the invention: EXAMPLE A strip of soft steel of a width of 32 mm and a thickness of 1.8 mm is shaped after lubrication by means of two sets of horizontal rollers into a section having substantially the form of a trough, deeper than it is wide.

Some welding powder is continuously poured in proportioned quantity into the trough as it moves past under a receptacle supplying the powder. The powder is covered over with a thin sheet bent into an arc of a circle so that the turned-down edges of the sheet touch the sides of the trough and isolate the powder at the bottom of the trough.

The trough, partially filled with a continuous line of powder, is pulled through a die in which the extremities of the U-section are turned in so that they engage one another.

The unclosed casing thus obtained is cleaned by flame and brought to a welding station where the joint of the casing is closed.

At the exit of the welding station the resulting welded cored preform is lubricated and passes through at least one die to obtain a minimal gripping of the powder.

A more intense diameter reduction to obtain a wire with substantially oval section is effected by drawing. The final oblong form is obtained by flattening of this oval section wire. The final cored wire produced is a strip having a width of 8 mm and a thickness of 0.5 mm.

WHAT WE CLAIM IS: 1. A process of manufacturing a welding wire having a core of powder and a tubular metallic member enclosing the core, the process including forming from a metal band an open channel having a pair of lateral flanks with upper end edges extending longitudinally of the channel, partially filling the channel over its length with the powder, covering the powder in the channel over at least a portion of its length with a strip which extends partially around the powder and holds it at the bottom of the channel to keep it away from the said upper end edges of said flanks, closing the channel by bringing said end edges into abutment with each other and welding them to each other, and working the resulting preform to a cored wire of a cross-section having a width greater than its thickness.

2. A method according to claim 1 wherein the finished cored wire is of oblong crosssection.

3. A method according to claim 2 wherein the preform is drawn to yield a cored wire of substantially circular or oval section and the latter is flattened to yield the finished cored wire.

4. A method according to claim 1 or 2 wherein the preform is worked by drawing and/or flattening to yield the finished cored wire.

5. A method according to any of claims 1 to 4 wherein the finished cored wire has a crosssection of a width at least five times its thickness.

6. A cored welding wire obtained by a method according to any of claims 1 to 5.

7. A cored welding wire according to claim 6 in which the powder constitutes between 10 and 70 wt.% of the cored wire.

8. A cored welding wire according to claim 7 in which the powder constitutes between 20 and 70 wt.% of the cored wire.

9. A cored welding wire according to claim 6, 7 or 8 which is at least 0.3 mm thick.

10. A cored welding wire according to any of claims 6 to 9 having a metal coating.

11. A method of making a cored welding wire, the method being substantially as described in the Example.

12. A cored welding wire substantially as described in the Example.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (12)

**WARNING** start of CLMS field may overlap end of DESC **. The amount of powder enclosed in the envelope is usually between 10 or 20% and 70% of the total weight of the cored wire and it is uniformly distributed along the length of the wire. The composition of the powder and that of the metallic envelope are chosen in known manner according to the uses and performances of the filled wires to be produced. The cored wires are watertight when produced and they remain so during subsequent treatments. Also they can be rolled up, unrolled, treated in gaseous or liquid media and stored without fear of alteration or contamination of the powder core. The envelope of these cored wires can be given a metallic coating, e.g. of copper. The cored flat wires produced in accordance with the invention are particularly well suited to the preparation of wide welds in the processes of assembling with or without support, or replenishing and coating metal pieces by arc welding with or without protective gas or with flux. Cored wires produced in accordance with the invention are particularly well suited for replenishing and coating pieces with nonoxidisable steels, steels resistant to wear and to impact, martensitic chromium steels, austenitic manganese steels, chromium-manganese tempering steels and high-speed steels. The following is one example of the method according to the invention: EXAMPLE A strip of soft steel of a width of 32 mm and a thickness of 1.8 mm is shaped after lubrication by means of two sets of horizontal rollers into a section having substantially the form of a trough, deeper than it is wide. Some welding powder is continuously poured in proportioned quantity into the trough as it moves past under a receptacle supplying the powder. The powder is covered over with a thin sheet bent into an arc of a circle so that the turned-down edges of the sheet touch the sides of the trough and isolate the powder at the bottom of the trough. The trough, partially filled with a continuous line of powder, is pulled through a die in which the extremities of the U-section are turned in so that they engage one another. The unclosed casing thus obtained is cleaned by flame and brought to a welding station where the joint of the casing is closed. At the exit of the welding station the resulting welded cored preform is lubricated and passes through at least one die to obtain a minimal gripping of the powder. A more intense diameter reduction to obtain a wire with substantially oval section is effected by drawing. The final oblong form is obtained by flattening of this oval section wire. The final cored wire produced is a strip having a width of 8 mm and a thickness of 0.5 mm. WHAT WE CLAIM IS:

1. A process of manufacturing a welding wire having a core of powder and a tubular metallic member enclosing the core, the process including forming from a metal band an open channel having a pair of lateral flanks with upper end edges extending longitudinally of the channel, partially filling the channel over its length with the powder, covering the powder in the channel over at least a portion of its length with a strip which extends partially around the powder and holds it at the bottom of the channel to keep it away from the said upper end edges of said flanks, closing the channel by bringing said end edges into abutment with each other and welding them to each other, and working the resulting preform to a cored wire of a cross-section having a width greater than its thickness.

2. A method according to claim 1 wherein the finished cored wire is of oblong crosssection.

3. A method according to claim 2 wherein the preform is drawn to yield a cored wire of substantially circular or oval section and the latter is flattened to yield the finished cored wire.

4. A method according to claim 1 or 2 wherein the preform is worked by drawing and/or flattening to yield the finished cored wire.

5. A method according to any of claims 1 to 4 wherein the finished cored wire has a crosssection of a width at least five times its thickness.

6. A cored welding wire obtained by a method according to any of claims 1 to 5.

7. A cored welding wire according to claim 6 in which the powder constitutes between 10 and 70 wt.% of the cored wire.

8. A cored welding wire according to claim 7 in which the powder constitutes between 20 and 70 wt.% of the cored wire.

9. A cored welding wire according to claim 6, 7 or 8 which is at least 0.3 mm thick.

10. A cored welding wire according to any of claims 6 to 9 having a metal coating.

11. A method of making a cored welding wire, the method being substantially as described in the Example.

12. A cored welding wire substantially as described in the Example.