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SOME APPLICATIONS OF EXPLOSIVE

METALWORKING FOR ALUMINUM INDUSTRY

A.Z.Bogunov, A.A.Kuzovnikov

JSC « Pulse technologies »660036, Krasnoyarsk, Russia, POB 26780,

e-mail: limom1@yandex.ru

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JSC «Pulse technologies»

• Fabrication of the steel-aluminum transition inserts for anode holder of aluminum electrolyzer.

• Developed technology of explosive welding with dovetail type bond of connection.

• About 120 000 steel-aluminum inserts were manufactured and delivered for aluminum industry.

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Objectives for explosive metalworking

Decrease of voltage drop

Treatment of cathode bar for

recycling

Cooling of Shell

Detachable Contact joint

Connection of bus bar

Bimetallic inserts

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Removal the cast-iron coating from cathode bar 1

Сathode bar casting by melting cast iron at blocks

Used cathode bar with cast iron coating

Сathode bar with coating

White cast iron, thickness 10-15 mm

Cast iron, thickness 20-25 mm

Welding at the casting place

Cast-iron

Steel

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Removing cast iron coating from cathode bar for recycling 2

Recycling cathode bar

1.Chipping cast iron at the side and at the bottom, HE charge 1,6 kg/m2.Partial removal from casting side, HE charge 1 kg/m3.Milling welding patch

Packaged ammonite№6

Base cathode bar

•High economic efficiency•There are problems with nonflat geometry of used cathode bar

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Iron cathode- descent detachable connections

1 – copper aluminum contact; 2 – contact copper layer; 3 – flexible multilayer descent; 4 – cathode bus bar; 5 – cathode bar;6 – hardware.

Contact 1Copper 5mm, aluminum 50mm

Contact 2Copper 2mm, aluminum 40mm

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Anode descents for electrolizer with

side current leads

Option1:Aluminum with thickness 30 – 40 mm was welded at the end of copper strip with thickness 10 mm

Option2:Aluminum with thickness 10 – 20 mm was welded overlapping at the 1/3 copper strip with thickness 10 mm

Connection Cu – Al is made by explosive welding instead of fusion welding:• High reliability of connection• Substantial reduction of copper consumption

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Split connection anode rod – anode bus bar

Contact copper-aluminum plates are mounted on anode

bus bar , copper 2mm

Copper coating at the side surface of the anode rod,

copper 2mm

Contact Al – Al was changed by contact Cu - Cu

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Bimetal contacts with riffled surface 1

Different types of copper surface asperities on aluminum base, size 2

mm

Titanium surface asperities on the

aluminum base, size 0,35mm

•Surface asperities are made from more hard material than base•Asperities are penetrated into the opposite surface and cut through the oxide films • Eliminating of the state of the contact surface (non-flatness, roughness, contamination) influence

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Bimetal contacts with riffled surface 2

Processing concept of contact with riffled

surface

Voltage drop-contact pressure dependence

30x30mm, current 100А Flat surface

Riffled surface, asperities 2 mm

SS-AlNi-Al

Р, KPa

U, mV

U decrease in 20 – 50 times for pure contact and in 50 -100 times for contamination contactU has inverse proportionality asperities size•At the small loading U for pyramid type asperities in 2 times smaller than for stripe asperities

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Bimetal cooling ribs of pot shell

•Working temperature 4000С •Life time – more than 5 years

Option 1:Explosive welding fabricated rib

Stimulation of electrolysis process of aluminum production

(pat.RF 2322682)

Option 2:Transition pieces Al 10 mm – Ti 0,5mm – steel 20mm, dovetail connection

Steel-aluminum cooling ribs

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Bridge connections aluminum bus bar 1

•The works must de done at the shop conditions •Minimal HE charge •Explosive localizer is a part of charge construction.

Cutoffs of detonation cord 10 g/m, diam.5

mm

Explosive welding on a base of detonation

cord

Tensile strength 80-110 МРа, waveless bond

HE consumption :Al 5mm (2 plate) – 0,05 g/сm2

Al 15mm – 0,1 g/сm2

Stationary detonation D ≈ 3,5 кm/s

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Aluminum thickness

mm

Inclination angle, grade

Tamping Result

5 0 yes welding

6 0 no/yes No/ weldin

g

10 0 no/yes No

10 5 yes welding

10 7,5 yes welding

10 10 yes welding

15 11 yes welding

Bridge connections aluminum bus bar 2

Bridge bus bar butt connection, 2 bridges with thickness 15 mm

Overlapping connection bus bar, 2 bridges with thickness 15 mm

L – likes connection , thickness of bridge 10 mm

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Butt connection thick aluminum bus bar

•Works must be done at the shop conditions•Minimal HE charge •Bus bar thickness– 80 mm•Not overlapping connection

Standoff

Busbar Busbar

Insert with bore filled by HE

Wave bond (Ammonite №6)

D

HE consumption :Detonation cord - 0,25 g/сm2

Ammonite №6 – (0,1-0,13) g/сm2

Average tensile strength 40 MРаBore (5,5 – 6) mmStandoff (0,5 - 1) mm

Welding region

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Conclusion

1. Used cathode bars mounted in a block by pouring cast iron may be cleaned by the explosion for recycling.

2. Bimetallic contacts with the riffled surface can provide a significant reduction in the voltage drop in high-current connections.

3. Different versions of bimetallic cooling ribs of pot shell were developed for intensification of aluminum electrolysis.

4. Explosive charges on the basis of detonation cord provide welding of thick aluminum up to 15 mm for the bridge connection of aluminum bus bar.

5. The technology for the butt connections of thick aluminum bus bar was developed.

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Thank for your

attention