Material Stock Selection for Stretch Forming

The Stretch Forming cost model selects stock for a part based on the following:

• Blank thickness

• Length and width of the stretch-direction-aligned bounding rectangle of the flattened part (that is, length and width of the smallest rectangle with one side aligned with the stretch direction and an interior that contains the entire outline of the flattened part)

• Length and width addendum values (providing additional material for the machine jaws to grip), specified by cost model variables

The cost model finds the actual stock with both the following:

• Thickness that is within 0.5mm of the blank thickness

• One of the following:

o Smallest length greater than or equal to the part’s minimum required stock length, and smallest width greater than or equal to the part’s minimum required stock width

o Smallest length greater than or equal to the part’s minimum required stock width, and smallest width greater than or equal to the part’s minimum required stock length

The part’s minimum required stock length is the given by the following:

Minimum Required Stock Length =

Xsection-aligned SER Length + (Length Addendum * 2)

where

• Xsection-aligned SER length is the value of the property Curve Length Extended Aligned for the Xsection aligned with the stretching direction (that is, for the transverse Xsection if the current routing includes Stretch Form—Transverse, and for the longitudinal Xsection if the current routing includes Stretch Form—Longitudinal--see Stretch Form Process Feasibility).

• Length addendum is the value of the cost model variable stretchFormAlignedMaterialAddendum (500mm in starting point VPEs).

The part’s minimum required stock width is the given by the following:

Minimum Required Stock Width =

Xsection-aligned SER Width + (Width Addendum * 2)

where

• Xsection-aligned SER width is the value of the property Curve Length Extended Orthogonal for the Xsection aligned with the stretching direction (that is, for the transverse Xsection if the current routing includes Stretch Form—Transverse, and for the longitudinal Xsection if the current routing includes Stretch Form—Longitudinal--see Stretch Form Process Feasibility).

• Addendum is the value of the cost model variable stretchFormOrthogonalMaterialAddendum (50mm in starting point VPEs).

If no suitable actual stock is found, aPriori selects virtual stock with the required dimensions.

The cost model currently assumes only one part is made per stock unit.