TAILOR WELDED BLANKSJithesh.E04107

Fuel conservation policySafety mandatesEnvironmental concerns

What are Tailor Welded Blanks?

What are Tailor welded blanks?Combining various steel options into a welded blank to enable product and manufacturing engineers to tailor the blank so that steels best properties were located precisely within the part where they were needed.

Steps InvolvedDifferent blanks are blanked out from sheet metal.Nesting of blanks.Laser welding.Forming

Pre-welding considerations Blanking and notching Handling Stacking Shipping

Blank production Processes for Tailor Welded Blanks Before welding, most blanks will be produced in two ways: As rough blanks from shear line processing. As pattern blanks from die and press processing.

Types of welding considered for TWB Laser Beam Resistance Mash Seam High-Frequency Induction Electron Beam (non-vacuum)

The most prevalent welding processes in use today are the laser beam butt-welding and resistance mash seam lap welding.

Types of laser welding involvedLaser welding with fixed opticsLaser welding with moving optics (X axis or X and Y axes) Laser welding with filler wireLaser beam weaving

Laser Welding of Blanks

Normal cut edge not possible for laser beam welding

With low carbon content filler wire, it is possible to decrease the hardness of the welded bead

Beam Weaving

Which welding when?

Potential Benefits of Tailor Welded Blanks Fewer partsFewer diesFewer spot welds Reduced design and development time Lower manufacturing costs Less material input, better utilization of steel Weight reduction Improved dimensional accuracy Improved structural integrity Improved safety Increased offal utilization and reduced scrap

Just guess how many TWB are being used in a passenger car?

A Pillar ReinforcementWind Shield FrameMotorCompartment railBumper ReinforcementFloor panFrame RailFront door innerRear door innerBody side FrameWheel house panelDeck lidCenter Pillar

Product design ConsiderationsPart integration and tooling cost reductionImproved material yieldWeight reductionImproved structure

Part integration and tooling cost reductionBy integrating sheets of different strengths and thicknesses into a tailor welded blank, many separate parts and reinforcements can be eliminated. This has a significant impact on tooling investment and operational costs Toyota reports the elimination of 38 dies by using tailor welded blanks with different strength components for the same application in a Lexus model

Improved structureIn addition to improved cost benefits, tailor welded blanks can provide on increase in structural stiffness resulting from the reinforcements being integrated into the structure and the structure itself having continuous weld joints rather than the components being attached with localized spot welds

Improved material yieldParts which are rectangular or trapezoidal in shape (such as roof panels or hood outers) will have a higher yield than parts that require irregular pattern shaped blanks. Yield rates as low as 29 percent have been documented for irregular parts.

Statistics

Weight ReductionA weight reduction of 19.7 pounds achieved on the Ford Taurus if tailor welded blanks were used for as few as 10 parts.

Other salient features

CorrosionThe corrosion resistance of a part made from a tailor welded blank will be greatly influenced by sheet steel and weld surface conditions, including paint adhesion. The corrosion performance ultimately is also a function of the width of the weld and heat-affected zone

SealingAn often overlooked benefit of tailor welded blanks is the fact that no sealing compounds are needed at these weld joints. The weld is continuous, as opposed to resistance spot welds, which are intermittent. Savings result from the elimination of sealing investment costs and sealing operations. In addition, weight savings and environmental benefits also may be achieved

Location of weldingIt is advisable to avoid placing the weld directly in stretch flange areas (e.g., corners of window or door openings.)

Nesting of blanks

Preferred designs for Welding

How it a TWB fails?Blank outlineDraw die/Punch lineWeld lineAfter drawWeld line Before draw

Formability checkingThe formability of welds for tailor welded blanks has been measured with tensile tests, limiting dome height and other simulative tests, hydraulic bulge tests and hole expansion tests.

Failure Modes for Tailor-Welded Blanks

Variations of Total Tensile Elongation with Weld Speed for Various Welds

Schematic of the Tooling for the Formability Test

What demands for TWB?Its greatest potential lies in the area of with different thicknesses, coatings and material grades. Pressure for tailor-welded blanks comes largely from the demands for lighter, stronger, more complicated vehicle designs planned for future yearsReduced Weight in VehicleImproved Assembly (Hemming)

Growth!20 million tailor-welded blanks in 1999 to more than 90 million in 2005, GM has one of the largest tailor-welded blank volume applications anywhere -- the GMT 800 light-truck platform that uses these specialty blanks for the side frames Audi's new Lamborghini Gallardo with the world's first production ready aluminum tailor welded blank designed to further reduce vehicle body weight and assembly costs

Growth (Contd)Vehicle manufacturers are today increasingly turning to tailor welded blanks to help increase structural integrity while reducing vehicle component weight for lower fuel consumption and CO2 emissions

Thank You

Resistance Mash Seam Welding Resistance mash seam tailor welded blanks have an overlap seam joint that is 10-50 percent thicker than the thicker of the materials and a heat-affected zone approximately twice the width of the weld. The reduction of thickness at the joint is limited by the necessity to avoid weld current shunting, depending on the gauge of the materials.

The thickened joint can be reduced to about 10 percent more than the heavier gauge material by post-weld planishing. The planishing process involves compressing the weld joint between steel rollers. This can be done immediately after welding at a temperature above recrystallization (about 550C/1000F for sheet steel) as hot planishing or after the weld has cooled as cold planishing. Hot planishing has better formability characteristics, but coated sheet steels can be a problem for this process due to coating pick-up on the planishing rollers. ()

Laser Beam Welding The laser beam tailor welded blank has a butt-welded joint with a slight concavity at the joint with a narrower (about 1.0 mm/0.04 inch) heat-affected zone. Minimizing concavity of the weld joint is critical to good formability and mechanical properties. Minimum concavity in the weld joint is usually achieved by precision shearing the blank edges to be welded. A good fit up prior to welding and a laser beam alignment with respect to the joint are important for a good laser weld.()

When welding speed is reduced!

High-Frequency Induction Welding This type of weld, developed for tailor welded blanks by Elva Induction and Volvo, is a butt-upset joint process that has a thickening at the joint and a heat-affected zone similar in width to the resistance mash seam weld. Grinding the joint can remove the thickened growth to improve fit up in assemblies. Induction welding has a faster cycle time and lower operating costs than laser beam or resistance mash seam welding processes, according to Volvo, co-developed of the process. Volvo personnel indicate these factors could make this type of weld joint a viable alternative to some resistance mash seam and laser beam welding applications in the future ()

Frame Rail()

Bumper reinforcement

Front inner panel

Motor compartment()

BibliographyTailor welded blanks manufacturing manual.www.autosteel.org