Computer implemented method and system for generating slope synchronized tool paths for incremental sheet forming

A computer implemented method for generating a series of slope synchronized tool paths for incremental sheet forming of an aircraft contoured part, the computer implemented method comprising the steps of:

• providing a computer system comprising a computer having a processor device, and comprising a modeling application and a slope synchronized tool path application, each implemented by a computer readable software program and each executed by the computer;
• performing, with the computer and the modeling application, a surface discretization of a three-dimensional geometry of the aircraft contoured part, to produce a surface mesh of polygons that approximates the three-dimensional geometry of the aircraft contoured part;
• performing, with the computer and the slope synchronized tool path application, a slope synchronized tool path application execution comprising the substeps of:
• defining a plurality of horizontal planes equally spaced apart at a plurality of Z values along a Z-axis, where each of the plurality of horizontal planes intersects the surface mesh of polygons that approximates the three-dimensional geometry of the aircraft contoured part;
• determining, for each of the plurality of horizontal planes, a slope factor based on a maximal Z-axis component of a normal vector for each polygon intersecting each of the plurality of horizontal planes, to define a lookup table of Z values and slope factor values that correspond to the Z values;
• and
• setting an initial Z coordinate corresponding to a starting portion of the surface mesh, as a current Z coordinate;
• the slope synchronized tool path application execution then iteratively:
• calculating a stepdown as a sum of a minimum stepdown and a percentage of a maximum stepdown less the minimum stepdown, to obtain a calculated stepdown, the percentage based on a current slope factor for the current Z coordinate, that is calculated based on the lookup table of the Z values and the slope factor values that correspond to the Z values;
• decrementing the current Z coordinate by the calculated stepdown;
• and
• determining an intersection of the surface mesh with a current horizontal plane at the current Z coordinate, to define a collection of vectors in the current horizontal plane, and sorting the collection of vectors in a tip-to-tail arrangement, to produce a contour tool path loop for the current Z coordinate, wherein the slope synchronized tool path application creates a plurality of contour tool path loops that are each respectively spaced apart by slope synchronized stepdowns, to obtain the series of slope synchronized tool paths;
• and
• sending an output file, using the computer, to a numerically controlled incremental sheet forming (ISF) machine, which causes the numerically controlled incremental sheet forming (ISF) machine to direct an incremental sheet forming (ISF) tool along the series of slope synchronized tool paths comprising the plurality of contour tool path loops spaced apart by the slope synchronized stepdowns, to incrementally form the aircraft contoured part.

A computer implemented system for generating a series of slope synchronized tool paths for incremental sheet forming (ISF) of a contoured part, the computer implemented system comprising:

• a computer having a processor device and a modeling application implemented by a first computer readable software program and executed by the computer, the modeling application adapted to perform a surface discretization of a three-dimensional geometry of the contoured part, to produce a surface mesh of polygons that approximates the three-dimensional geometry of the contoured part;
• and
• a slope synchronized tool path application implemented by a second computer readable software program and executed by the computer, the slope synchronized tool path application adapted to:
• define a plurality of equally spaced apart Z values along a Z-axis, where each of the plurality of equally spaced apart Z values intersects the surface mesh of polygons that approximates the three-dimensional geometry of the contoured part;
• determine, for each of the plurality of equally spaced apart Z values, a slope factor based on a maximal Z-axis component of a normal vector, for each polygon intersecting each of the plurality of equally spaced apart Z values, to define an array of Z values and slope factor values that correspond to the Z values;
• and
• set an initial Z coordinate corresponding to a starting portion of the surface mesh, as a current Z coordinate;
• the slope synchronized tool path application then adapted to iteratively:
• calculate a stepdown as a sum of a minimum stepdown and a percentage of a maximum stepdown less the minimum stepdown, to obtain a calculated stepdown, the percentage based on a current slope factor for the current Z coordinate, that is calculated based on the array of the Z values and the slope factor values that correspond to the Z values;
• decrement the current Z coordinate by the calculated stepdown;
• and
• determine an intersection of the surface mesh with a horizontal plane at the current Z coordinate, to define a collection of vectors in the horizontal plane, to produce a contour tool path loop for the current Z coordinate, wherein the slope synchronized tool path application creates a plurality of contour tool path loops that are each respectively spaced apart by slope synchronized stepdowns, to obtain the series of slope synchronized tool paths,
• wherein the computer sends an output file to a numerically controlled incremental sheet forming machine, which causes the numerically controlled incremental sheet forming machine to direct an incremental sheet forming tool along the series of slope synchronized tool paths comprising the plurality of contour tool path loops spaced apart by the slope synchronized stepdowns, to incrementally form the contoured part.