LIES_NEAR Relation

The LIES_NEAR relation is used to determine feasibility for various operations, for example, for waterjet cutting on perimeter GCDs (waterjet cutting cannot be performed on a perimeter that lies too close to a hole). Feasibility is defined in terms of the ratio of minimum wall thickness to part thickness, and minimum wall thickness is defined by the distance property of the LIES_NEAR relation between the GCD on which the operation is to be performed and the GCD closest to it.

Geometry extracts a LIES_NEAR relation for sufficiently close pairs of GCDs of the following types:

• Perimeter/perimeter pairs

• Perimeter/simple hole pairs

• Perimeter/multistep hole pairs

provided the perimeters have isHeightDirection = true and the holes are not blind and have axes parallel to the height direction.

With the site variables listed below, you can control what counts as sufficiently close:

• maxRelatedDistanceMm (6.0 in aPriori starting point VPEs)

• maxRelatedThickness (6.0 in aPriori starting point VPEs)

• relatedPerimeterCoeff (0.1 in aPriori starting point VPEs)

• relatedPerimeterIntercept (101.6 in aPriori starting point VPEs),

• relatedPerimeterMaxMm (10.0 in aPriori starting point VPEs),

• relatedPerimeterMaxMmCutoff (12.7 in aPriori starting point VPEs)

A perimeter/hole pair is sufficiently close if the distance between them is less than or equal to the following quantity:

GeneralDistance = max (maxRelatedThickness * Blank Thickness, maxRelatedDistanceMm)

A perimeter/perimeter pair is sufficiently close if the distance between them is less than or equal to the following quantity:

min(relatedPerimeterMaxMmCutoff, max (GeneralDistance, PerimeterLineFormula))

where

PerimeterLineFormula = relatedPerimeterMaxMm + relatedPerimeterCoeff *

[(min (perimeter1.serLength, perimeter2.serLength)) - relatedPerimeterIntercept]