EPNM 2012 Strasbourg France New Explosive Welding Technique

EPNM -2012 Strasbourg, France New Explosive Welding Technique for Production of Bimetal Plane Bearings B. S. Zlobin 1, V. V. Sil’vestrov 2, A. A. Shtertser 1*, A. V. Plastinin 2 1 Design & Technology Branch of Lavrentyev Institute of Hydrodynamics SB RAS 2 Lavrentyev Institute of Hydrodynamics SB RAS Novosibirsk, Russia *asterzer@mail. ru

Bimetal Plane Bearings in Internal Combustion Engine 1 - cylinder and piston, 2 - crankshaft, 2 3 - flywheel There are crankshaft main bearings and connectingrod bearings in the engine. Bearing works under forcefeed lubrication and reduces friction between shaft journal and conrod or engine case. 1 3 Bimetal Plane Bearings are the important elements of engine, affecting its lifetime between capital repairs.

Bearing Production Bimetal plane bearings are produced by different technologies, mostly by rolling and lining. Since 1990 -es explosive welding is employed in commercial production of crankshaft plane bearings for heavy diesel engines in Russia [1]. Plane bearing workpiece in a form of bimetal plate is made by explosive welding, where flyer plate is made from aluminum/tin antifriction alloy, and base plate from low carbon steel. 1 B. S. Zlobin, Commercial production of bimetal plane bearings by explosive welding in Russia, Proceed. EXPLOMET’ 95 Intern. Conf. (El Paso, TX, August 1995) - Elsevier Science B. V. 1995, pp. 917 -921.

EXPLOSIVE WELDING LAYOUT 5 4 3 2 D h 1 6 1 - base plate, 2 - flyer plate, 3 - explosive charge, 4 - detonation front, 5 - detonation products, 6 - ground (anvil), D - detonation velocity, - collision angle, h - gap. Important welding parameter: R = mass of explosive / flyer plate mass.

Flyer Plate Design Aluminum foil, t 0. 15 mm 2. 2 Antifriction alloy (Al. Sn 20 Cu 1*, Al. Sn 10 Pb 2 etc). *Glyco 74 Antifriction alloy is made by rolling technique and is supplied in aluminum cover

Explosive Chamber KV-7 Technical parameters: - explosive charge mass 7 kg (trotyl equivalent); - mass 35 ton; - overall dimensions: length 4640 mm, width 2800 mm, height 4300 mm (open); - shell internal diameter 2200 mm; - shell thickness 60 mm; - worktable diameter 1000 mm. Designed and Produced at the Design &Technology Branch of Lavrentyev Institute of Hydrodynamics SB RAS

EXPLOSIVE WELDING Explosive welding (cladding): steel (base) plates are placed on the worktable. Plates are made from low carbon steel sheet by cutting, milling and grinding.

EXPLOSIVE WELDING Explosive welding (cladding): - antifriction alloy plates (flyer plates) are placed over steel plates with a certain air-gap; - explosive charge is placed onto flyer plates.

EXPLOSIVE WELDING Explosive welding (cladding): bimetal plates after explosion.

PRESS FORMING OPERATION punch spacer bimetal workpiece die After explosive welding, lining, and machining, bimetal goes through forming operation

BIMETAL HALF-FINISHED PLAIN BEARING LINERS Half-finished item has a semi-ring shape. Commercially produced products have steel layer thickness in the range from 3 to 20 mm, and antifriction layer thickness 2. 0 – 2. 2 mm. Semi-ring diameter varies from 90 to 260 mm.

Bimetal Plane Bearing Liner Bimetal Plane Bearing consists of two liners (upper and lower), which are made from pressed semi-rings by final machining. Connecting-rod bearing liners of locomotive diesel engine 5 D 49

Optimal Technology and Existing Technology Experiments show that high-quality explosive welding can be achieved at projection parameter R = 0. 8 – 1. 0. Antifriction layer thickness in completed bearing usually equals to 0. 6 – 1. 2 mm, so the flyer plate can have a thickness of 1. 5 mm. Therefore in optimal technology explosive charge with a thickness of not greater than 6 mm can be used for cladding. In existing technology ANFO (Ammonium Nitrate + Fuel Oil) explosive is used. Explosive charge thickness is 12 -14 mm, flyer plate thickness is 2. 2 mm. Projection parameter R = 1. 5 – 1. 7, and excessive energy is driven into produced bimetal.

Shortcomings of Existing Technology 1) Excessive energy driven into produced bimetal results in: - excessive and non-uniform deformation of bimetal steel layer, which create difficulties when finishing mechanical treatment of workpiece is performed; -high level of residual stresses in bimetal, which can result in loss of liner profile tolerances after manufacturing. 2) Use of 2. 2 mm thick flyer plate, instead of 1. 5 mm thick band, results in excessive production cost, as aluminum/tin antifriction alloy is rather expensive To change the technology from existing to optimal one parameter R and flyer plate thickness should be reduced. The problem: ANFO (Ammonium Nitrate + Fuel Oil) explosive has a critical layer thickness about 12 mm. To employ optimal technology another industrial explosive with lower critical layer thickness and detonation velocity D = 2 – 3 km/s should be developed.

Emulsion Explosive Last years in Lavrentyev Institute of Hydrodynamics SB RAS emulsion explosive (EE), detonating in low thickness layer with low detonation velocity was developed. Hollow glass microballoons are included in composition of this explosive with the aim to increase its detonation sensitivity. Laboratory experiments have shown that EE can be successfully employed in explosive cladding with flyer plate thickness less than 1 mm [1, 2]. EE density is 0. 62 0. 01 g/cm 3. Detonation velocity has weak dependence on layer thickness and changes from 2. 3 to 2. 6 km/s when thickness changes from 3. 5 to 25 mm. Critical thickness of flat charge in polyethylene casing (t 0. 5 mm) is less than 3. 5 mm. EE contains water solution of ammonium and sodium nitrate (oxidizer), paraffin (fuel), special emulsifying agent, and hollow glass microballoons. EE oxygen balance is close to zero. Emulsion density is 1. 41 0. 01 g/cm 3, oxidizer drop size is not greater than 2 µm. Microballoon average diameter is 58 µm, green density ~ 0. 15 g/cm 3. 1 V. V. Sil’vestrov and A. V. Plastinin, Investigation of Low Detonation Velocity Emulsion Explosives, Combustion, Explosion, and Shock Waves, 2009, Vol. 45, No. 5, pp. 618– 626 2 Silvestrov V. V. , Plastinin A. V. , and Rafejchik S. I. , Application of emulsion explosives for explosion welding, The Paton Welding Journal, 2009, N 11, p. 61 -64.

Welding using Emulsion Explosive Steel base plate was clad with 1. 4 mm thick antifriction band at R=0. 8 (EE charge thickness 6 mm). Specific mass of explosive was 36 g/dm 2, which is substantially lower than ANFO specific mass used in existing technology (about 100 g/dm 2). Microstructure of bonding zone (electron microscope LEO 420) – not wavy interface. Bond tensile strength is 85 -105 MPa (test machine ZDM-2. 5)

Welding using ANFO Steel base plate was clad with 2. 2 mm thick antifriction band at R=1. 5 Microstructure of bonding zone (electron microscope LEO 420) – wavy interface. Bond tensile strength is 104 MPa (test machine ZDM-2. 5)

Measurement of Residual Deformations Two steel plates with a size 8 x 110 x 275 mm were clad with Al. Sn 20 Cu 1 alloy using two technologies: 1) Explosive – ANFO, flyer plate thickness – 2. 2 mm, R = 1. 5; 2) Explosive – EE, flyer plate thickness – 1. 5 mm, R = 0. 8 To determine residual deformations, lines were scratched on the back surface of steel plate, and distance between scratches before and after explosive welding was measured. Results: Residual deformations are in 3 – 5 times greater if to use the technology (1). Residual deformations in the center and in the edges of steel base are very different in case of technology (1), and they are almost uniform in case of technology (2).

Measurement of Residual Deformations 1 2 Distribution of residual deformations, arising in the steel substrate: 1 – explosive welding using ANFO, 2 - explosive welding using emulsion explosive

Summary • Use of Emulsion Explosive, containing hollow microballoons, makes it possible to decrease substantially the explosive charge and flyer plate mass; • Use of reduced explosive charge permits to diminish residual deformations in manufactured workpiece. Residual stresses were not measured, but they evidently are diminished as well; • Development of new technology based on use of Emulsion Explosive will result in cutting of production costs.

In conclusion a few words about Waves in Nature What is the difference? Zebra has a wavy drawing on skin. Zoologists assert that zebra baby can recognize its mother by her individual skin pattern

Waves in Nature: bonding zone looks like zebra skin Plan view of titanium / steel welding zone. Wavy interface - specific feature of explosive welding.