COMPUTERIZED TOOL PATH GENERATION

REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. Patent Application No. 13/916,918, filed June 13, 2013, which is a divisional of U.S. Patent Application No. 13/036,726, filed February 28, 2011, published on August 30, 2012 as U.S. Published Patent Application No. 2012/0221140, now U.S. Patent No. 8,489,224, the disclosure of which is hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to systems and methodologies for automated tool path design and computer controlled machining and products produced thereby.

BACKGROUND OF THE INVENTION

Various systems and methodologies are known for automated tool path design and computer controlled machining.

SUMMARY OF THE INVENTION

The present invention seeks to provide improved systems and methodologies for automated tool path design and computer controlled machining and products produced thereby.

There is thus provided in accordance with a preferred embodiment of the present invention an automated computer-implemented method for generating commands for controlling a computer numerically controlled milling machine to fabricate a machined object from a workpiece having a Z-axis, the machined object being configured to facilitate subsequent finishing into a finished object, the method including defining a surface of the finished object, defining an offset surface, the offset surface being outside the surface of the finished object and separated therefrom by an offset distance, the offset surface defining an inner limiting surface of the machined object, defining a scallop surface, the scallop surface being outside the offset surface and separated therefrom by a scallop distance, the scallop surface defining an outer limiting surface of the machined object and calculating a tool path for the computer numerically controlled milling machine which produces multiple step-up cuts in the workpiece at multiple heights along the Z-axis, the multiple step up cuts in the workpiece resulting in the machined object, wherein surfaces of the machined object produced by the multiple step-up cuts all lie between the inner limiting surface defined by the offset surface and the outer limiting surface defined by the scallop surface and the number of multiple step-up cuts in the workpiece at multiple heights along the Z-axis and the areas cut in each of the multiple step-up cuts are selected so as to generally minimize the amount of workpiece material that is removed from the workpiece during the cuts while ensuring that the surfaces of the machined object produced by the multiple step-up cuts all lie between the inner limiting surface defined by the offset surface and the outer limiting surface defined by the scallop surface.

There is also provided in accordance with another preferred embodiment of the present invention an automated computer-implemented method for generating commands for controlling a computer numerically controlled milling machine to fabricate a machined object from a workpiece having a Z-axis, the machined object

being configured to facilitate subsequent finishing into a finished object, the method including defining a surface of the finished object, defining an offset surface, the offset surface being outside the surface of the finished object and separated therefrom by an offset distance, the offset surface defining an inner limiting surface of the machined object, defining a scallop surface, the scallop surface being outside the offset surface and separated therefrom by a scallop distance, the scallop surface defining an outer limiting surface of the machined object and calculating a tool path for the computer numerically controlled milling machine which produces multiple step-up cuts in the workpiece at multiple heights along the Z-axis, the multiple step up cuts in the workpiece resulting in the machined object, wherein surfaces of the machined object produced by the multiple step-up cuts all lie between the inner limiting surface defined by the offset surface and the outer limiting surface defined by the scallop surface and a decision of whether or not to cut the workpiece at a given location at each height of each of the multiple step-up cuts is a function of the required non-vertical slope of the finished object at the given location.

There is further provided in accordance with yet another preferred em.bodim.ent of the present invention an automated computer-implemented method for generating commands for controlling a computer numerically controlled milling machine to fabricate a machined object from a workpiece having a Z-axis, the machined object being configured to facilitate subsequent finishing into a finished object, the method including defining a surface of the finished object, defining an offset surface, the offset surface being outside the surface of the finished object and separated therefrom by an offset distance, the offset surface defining an inner limiting surface of the machined object, defining a scallop surface, the scallop surface being outside the offset surface and separated therefrom by a scallop distance, the scallop surface defining an outer limiting surface of the machined object and calculating a tool path for the computer numerically controlled milling machine which produces multiple step-up cuts in the workpiece at multiple heights along the Z-axis, the multiple step up cuts in the workpiece resulting in the machined object, wherein surfaces of the machined object produced by the multiple step-up cuts all lie between the inner limiting surface defined by the offset surface and the outer limiting surface defined by the scallop surface; and a decision as to at which height each of the multiple step-up cuts is made is a function of the required non-vertical slope of the finished object at the given height at various locations on the finished object.

Preferably, the function is a function of the smallest slope of the finished object at the given height.

There is also provided in accordance with another preferred embodiment of the present invention a method for machining a workpiece having a Z-axis, employing a computer numerically controlled milling machine, to fabricate a machined object from the workpiece, the machined object being configured to facilitate subsequent finishing into a finished object, the method including defining a surface of the finished object, defining an offset surface, the offset surface being outside the surface of the finished object and separated therefrom by an offset distance, the offset surface defining an inner limiting surface of the machined object, defining a scallop surface, the scallop surface being outside the offset surface and separated therefrom by a scallop distance, the scallop surface defining an outer limiting surface of the machined object, calculating a tool path for the computer numerically controlled milling machine which produces multiple step-up cuts in the workpiece at multiple heights along the Z-axis, the multiple step up cuts in the workpiece resulting in the machined object, wherein surfaces of the machined object produced by the multiple step-up cuts all lie between the inner limiting surface defined by the offset surface and the outer limiting surface defined by the scallop surface and the number of multiple step-up cuts in the workpiece at multiple heights along the Z-axis and the areas cut in each of the multiple step-up cuts are selected so as to generally minimize the amount of workpiece material that is removed from the workpiece during the cuts while ensuring that the surfaces of the machined object produced by the multiple step-up cuts all lie between the inner limiting surface defined by the offset surface and the outer limiting surface defined by the scallop surface and directing a computer controlled machine tool along the tool path.

There is further provided in accordance with yet another preferred embodiment of the present invention a method for machining a workpiece having a Z-axis, employing a computer numerically controlled milling machine, to fabricate a machined object from the workpiece, the machined object being configured to facilitate subsequent finishing into a finished object, the method including defining a surface of the finished object, defining an offset surface, the offset surface being outside the surface of the finished object and separated therefrom by an offset distance, the offset surface defining an inner limiting surface of the machined object, defining a scallop surface, the scallop surface being outside the offset surface and separated therefrom by a scallop distance, the scallop surface defining an outer limiting surface of the machined object, calculating a tool path for the computer numerically controlled milling machine which produces multiple step-up cuts in the workpiece at multiple heights along the Z-axis, the multiple step up cuts in the workpiece resulting in the machined object, wherein surfaces of the machined object produced by the multiple step-up cuts all lie between the inner limiting surface defined by the offset surface and the outer limiting surface defined by the scallop surface and a decision of whether or not to cut the workpiece at a given location at each height of each of the multiple step-up cuts is a function of the required non-vertical slope of the finished object at the given location and directing a computer controlled machine tool along the tool path.

There is even further provided in accordance with still another preferred embodiment of the present invention a method for machining a workpiece having a Z-axis, employing a computer numerically controlled milling machine, to fabricate a machined object from the workpiece, the machined object being configured to facilitate subsequent finishing into a finished object, the method including defining a surface of the finished object, defining an offset surface, the offset surface being outside the surface of the finished object and separated therefrom by an offset distance, the offset surface defining an inner limiting surface of the machined object, defining a scallop surface, the scallop surface being outside the offset surface and separated therefrom by a scallop distance, the scallop surface defining an outer limiting surface of the machined object, calculating a tool path for the computer numerically controlled milling machine which produces multiple step-up cuts in the workpiece at multiple heights along the Z-axis, the multiple step up cuts in the workpiece resulting in the machined object, wherein surfaces of the machined object produced by the multiple step-up cuts all lie between the inner limiting surface defined by the offset surface and the outer limiting surface defined by the scallop surface and a decision as to at which height each of the multiple step-up cuts is made is a function of the required non-vertical slope of the finished object at the given height at various locations on the finished object and directing a computer controlled machine tool along the tool path.

Preferably, the function is a function of the smallest slope of the finished object at the given height.

In accordance with a preferred embodiment of the present invention the calculating the tool path includes selecting the height of each of the multiple step-up cuts to be the maximum height which ensures that each of the surfaces that are cut at that height lie between the inner limiting surface defined by the offset surface and the outer limiting surface defined by the scallop surface.

Preferably, the calculating the tool path includes selecting whether or not to cut the workpiece at a given location at each height of each of the multiple step-up cuts. Additionally or alternatively, the calculating the tool path includes selecting the width of the cut at a given location at each height of each of the multiple step-up cuts.

in accordance with a preferred embodiment of the present, invention the tool path includes at least an initial tool path portion which defines an initial cut having vertical walls followed by at least one tool path portion which further machines the vertical walls of the initial cut into a plurality of stepwise vertical walls which together define the vertical slopes at each of the plurality of surface portions which lie adjacent the initial cut and correspond to the multiple step-up cuts.

Preferably, the calculating the tool path for the computer numerically controlled milling machine includes calculating the height of a step for a collection of mutually azimuthally separated points densely distributed all along a curve representing the intersection of a step forward edge wall with a lower step floor surface.

Additionally, the calculating the height of a step for a collection of mutually azimuthally separated points includes for each one of the collection of points, drawing an imaginary vertical line, parallel to the Z-axis to extend through the point and intersect at a scallop curve intersection point with the scallop surface, ascertaining the lowest height of a scallop curve intersection point corresponding to any of the collection of mutually azimuthally separated points and selecting the height for the step as being the lowest height of a scallop curve intersection point corresponding to any of the collection of mutually azimuthally separated points.

In accordance with a preferred embodiment of the present invention the automated computer-implemented method for generating commands for controlling a computer numerically controlled milling machine also includes taking an imaginary

slice through the workpiece perpendicular to the Z-axis at the height for the step, ascertaining a normal distance between the a point on the imaginary vertical line at the height and the scallop surface and if the normal distance for the one of the collection of points is less than a predetermined scallop tolerance, designating the one of the collection of points as a "good to cut" point.

There is even further provided in accordance with still another preferred embodiment of the present invention an automated computer-implemented method for generating commands for controlling a computer numerically controlled milling machine to fabricate an object from a workpiece, the method including ascertaining the available spindle power of the computer numerically controlled milling machine, automatically selecting, using a computer, a maximum depth and width of cut, which are a function at least of the available spindle power of the computer numerically controlled milling machine and configuring a tool path for a tool relative to the workpiece in which the tool path includes a plurality of tool path layers whose maximum thickness and width of cut correspond to the maximum depth and width of cut.

There is still further provided in accordance with yet another preferred embodiment of the present invention a method for machining a workpiece employing a computer numerically controlled milling machine, the method including ascertaining the available spindle power of the computer numerically controlled milling machine, automatically selecting, using a computer, a maximum depth and width of cut, which are a function at least of the available spindle power of the computer numerically controlled milling machine, configuring a tool path for a tool relative to the workpiece in which the tool path includes a plurality of tool path layers whose maximum thickness and width of cut correspond to the maximum depth and width of cut and directing a computer controlled machine tool along the tool path.

Preferably, the method also includes varying at least one additional parameter of the milling machine as a function of the available spindle power. Additionally, the at least one additional parameter of the milling machine is at least one of feed speed and rpm.

There is still further provided in accordance with yet a further preferred embodiment of the present invention an automated computer-implemented method for

generating commands for controlling a computer numerically controlled milling machine to fabricate an object having a relatively thin wall from a workpiece, the method including automatically selecting, using a computer, a tool path having the following characteristics: initially machining the workpiece at first maximum values of cutting depth, cutting width, cutting speed and cutting feed to have a relatively thick wall at the location of an intended relatively thin wall, reducing the height of the relatively thick wall to the intended height of the intended relatively thin wall and thereafter reducing the thickness of the thick wall by machining the workpiece at second maximum values of cutting depth, cutting width, cutting speed and cutting feed, at least one of the second maximum values being less than a corresponding one of the first maximum values.

There is also provided in accordance with another preferred embodiment of the present invention a method for machining a workpiece employing a computer numerically controlled milling machine to fabricate an object having a relatively thin wall from the workpiece, the method including automatically selecting, using a computer, a tool path having the following characteristics: initially machining the workpiece at first maximum values of cutting depth, cutting width, cutting speed and cutting feed to have a relatively thick wall at the location of an intended relatively thin wall, reducing the height of the relatively thick wall to the intended height of the intended relatively thin wall and thereafter reducing the thickness of the thick wall by machining the workpiece at second maximum values of cutting depth, cutting width, cutting speed and cutting feed, at least one of the second maximum values being less than a corresponding one of the first maximum values and directing a computer controlled machine tool along the tool path.

There is also provided in accordance with another preferred embodiment of the present invention an automated computer-implemented method for generating commands for controlling a computer numerically controlled milling machine to fabricate an object, the method including ascertaining the extent of tool overhang of a tool being used in the computer numerically controlled milling machine, automatically selecting, using a computer, a tool path which is a function of the tool overhang, the tool path having the following characteristics: for a first tool overhang selecting a tool path having first maximum values of cutting depth, cutting width, cutting speed and cutting feed and for a second tool overhang which is greater than the first tool overhang, selecting a tool path having second maximum values of cutting depth, cutting width, cutting speed and cutting feed, at least one of the second maximum values being less than a corresponding one of the first maximum values.

There is even further provided in accordance with still another preferred embodiment of the present invention a method for machining a workpiece employing a computer numerically controlled milling machine, the method including ascertaining the extent of tool overhang of a tool being used in the computer numerically controlled milling machine, automatically selecting, using a computer, a tool path which is a function of the tool overhang, the tool path having the following characteristics: for a first tool overhang selecting a tool path having first maximum values of cutting depth, cutting width, cutting speed and cutting feed and for a second tool overhang which is greater than the first tool overhang, selecting a tool path having second maximum values of cutting depth, cutting width, cutting speed and cutting feed, at least one of the second maximum values being less than a corresponding one of the first maximum values and directing the tool along the tool path.

There is further provided in accordance with yet another preferred embodiment of the present invention an automated computer-implemented method for generating commands for controlling a computer numerically controlled milling machine to fabricate an object having a semi-open region, the method including estimating, using a computer, a first machining time for machining the semi-open region using a generally trichoidal type tool path, estimating, using a computer, a second machining time for machining the semi-open region using a generally spiral type tool path and automatically selecting, using a computer, a tool path type having a shorter machining time.

There is further provided in accordance with yet another preferred embodiment of the present invention a method for machining a workpiece using a computer numerically controlled milling machine to fabricate an object having a semi-open region, the method including estimating, using a computer, a first machining time for machining the semi-open region using a generally trichoidal type tool path, estimating, using a computer, a second machining time for machining the semi-open region using a generally spiral type tool path, automatically selecting, using a computer, a tool path type having a shorter machining time and directing a computer controlled machine tool along the tool path type having a shorter machining time.

Preferably, the generally spiral type tool path is characterized in that it includes: an initial spiral type tool path portion characteristic of machining a closed region, included within the semi-open region and having a relatively thick wall separating at least one side thereof from an open edge of the semi-open region and a plurality of tool paths suitable for removal of the relatively thick wall.

In accordance with a preferred embodiment of the present invent on the plurality of tool paths are suitable for cutting mutually spaced relatively narrow channels in the thick wall, thereby defining a plurality of thick wall segments and thereafter removing the plurality of thick wall segments. Additionally, the plurality of tool paths include spiral tool paths suitable for removing the plurality of thick wall segments.

There is even further provided in accordance with still another preferred embodiment of the present invention an automated computer-implemented method for generating commands for controlling a computer numerically controlled milling machine to fabricate an object having a channel open at both its ends and including an intermediate narrowest portion, the method including automatically selecting, using a computer, a tool path type having first and second tool path portions, each starting at a different open end of the channel, the first and second tool path portions meeting at the intermediate narrowest portion.

There is also provided in accordance with another preferred embodiment of the present invention a method for machining a workpiece using a computer numerically controlled milling machine to fabricate an object having a channel open at both its ends and including an intermediate narrowest portion, the method including automatically selecting, using a computer, a tool path type having first and second tool path portions, each starting at a different open end of the channel, the first and second tool path portions meeting at the intermediate narrowest portion and directing a computer controlled machine tool along the first and second tool path portions.

There is yet further provided in accordance with still another preferred embodiment of the present invention an automated computer-implemented method for generating commands for controlling a computer numerically controlled milling

machine to fabricate an object which fabrication involves cutting a workpiece at at least first and second different maximum depths of cut, wherein the first maximum depth of cut is greater than the second maximum depth of cut the method including automatically selecting, using a computer, at least first and second tool paths having corresponding first and second maximum values of cutting width, cutting speed and cutting feed, at least one of the second maximum values being greater than a corresponding one of the first maximum values.

There is even further provided in accordance with yet another preferred embodiment of the present invention a method for machining a workpiece using a computer numerically controlled milling machine to fabricate an object which fabrication involves cutting a workpiece at at least first and second different maximum depths of cut, wherein the first maximum depth of cut is greater than the second maximum depth of cut, the method including automatically selecting, using a computer, at least first and second tool paths having corresponding first and second maximum values of cutting width, cutting speed and cutting feed, at least one of the second maximum values being greater than a corresponding one of the first maximum values and directing a computer controlled machine tool along the at least first and second tool paths.

Preferably, the automatically selecting includes adjusting the first and second maximum values of cutting width, cutting speed and cutting feed to ensure that the mechanical load experienced by a milling tool is at a generally constant optimized value.

There is still further provided in accordance with yet a further preferred embodiment of the present invention an automated computer-implemented method for generating commands for controlling a computer numerically controlled milling machine to fabricate an object, wherein fabrication of the object involves calculating multiple tool paths requiring tool repositioning therebetween along a selectable repositioning path, the method including estimating, using a computer, a first repositioning time for a first repositioning path which includes travel in a clearance plane above a workpiece, estimating, using a computer, a second repositioning time for a second repositioning path which does not include tool travel in the clearance plane and automatically selecting, using a computer, a repositioning path having a shortest repositioning time.

There is further provided in accordance with another preferred embodiment of the present invention a method for machining a workpiece using a computer numerically controlled milling machine to fabricate an object, wherein fabrication of the object involves calculating multiple tool paths requiring tool repositioning therebetween along a selectable repositioning path, the method including estimating, using a computer, a first repositioning time for a first repositioning path which includes travel in a clearance plane above a workpiece, estimating, using a computer, a second repositioning time for a second repositioning path which does not include tool travel in the clearance plane, automatically selecting, using a computer, a repositioning path having a shortest repositioning time and directing a computer controlled machine tool along the repositioning path having the shortest repositioning time.

In accordance with yet another preferred embodiment of the present invention the second repositioning path is automatically selected by the computer from among possible multiple repositioning paths which do not include tool travel in the clearance plane on the basis of shortest repositioning time. Additionally, the multiple repositioning paths include repositioning paths which require raising of the tool and repositioning paths which do not require raising of the tool.

There is also provided in accordance with another preferred embodiment of the present invention an automated computer-implemented apparatus for generating commands for controlling a computer numerically controlled milling machine to fabricate a machined object from a workpiece having a Z-axis, the machined object being configured to facilitate subsequent finishing into a finished object, the apparatus including a tool path configuration engine operative for defining a surface of the finished object, defining an offset surface, the offset surface being outside the surface of the finished object and separated therefrom by an offset distance, the offset surface defining an inner limiting surface of the machined object, defining a scallop surface, the scallop surface being outside the offset surface and separated therefrom by a scallop distance, the scallop surface defining an outer limiting surface of the machined object and calculating a tool path for the computer numerically controlled milling machine

which produces multiple step-up cuts in the workpiece at multiple heights along the Z-axis, the multiple step up cuts in the workpiece resulting in the machined object, wherein surfaces of the machined object produced by the multiple step-up cuts all lie between the inner limiting surface defined by the offset surface and the outer limiting surface defined by the scallop surface and the number of multiple step-up cuts in the workpiece at multiple heights along the Z-axis and the areas cut in each of the multiple step-up cuts are selected so as to generally minimize the amount of workpiece material that is removed from the workpiece during the cuts while ensuring that the surfaces of the machined object produced by the multiple step-up cuts all lie between the inner limiting surface defined by the offset surface and the outer limiting surface defined by the scallop surface.

There is further provided in accordance with yet another preferred embodiment of the present invention an automated computer-implemented apparatus for generating commands for controlling a computer numerically controlled milling machine to fabricate a machined object from a workpiece having a Z-axis, the machined object being configured to facilitate subsequent finishing into a finished object, the apparatus including a tool path configuration engine operative for defining a surface of the finished object, defining an offset surface, the offset surface being outside the surface of the finished object and separated therefrom by an offset distance, the offset surface defining an inner limiting surface of the machined object, defining a scallop surface, the scallop surface being outside the offset surface and separated therefrom by a scallop distance, the scallop surface defining an outer limiting surface of the machined object and calculating a tool path for the computer numerically controlled milling machine which produces multiple step-up cuts in the workpiece at multiple heights along the Z-axis, the multiple step up cuts in the workpiece resulting in the machined object, wherein surfaces of the machined object produced by the multiple step-up cuts all lie between the inner limiting surface defined by the offset surface and the outer limiting surface defined by the scallop surface and a decision of whether or not to cut the workpiece at a given location at each height of each of the multiple step-up cuts is a function of the required non-vertical slope of the finished object at the given location.

There is even further provided in accordance with still another preferred embodiment of the present invention an automated computer-implemented apparatus for

generating commands for controlling a computer numerically controlled milling machine to fabricate a machined object from a workpiece having a Z-axis, the machined object being configured to facilitate subsequent finishing into a finished object, the apparatus including a tool path configuration engine operative for defining a surface of the finished object, defining an offset surface, the offset surface being outside the surface of the finished object and separated therefrom by an offset distance, the offset surface defining an inner limiting surface of the machined object, defining a scallop surface, the scallop surface being outside the offset surface and separated therefrom by a scallop distance, the scallop surface defining an outer limiting surface of the machined object and calculating a tool path for the computer numerically controlled milling machine which produces multiple step-up cuts in the workpiece at multiple heights along the Z-axis, the multiple step up cuts in the workpiece resulting in the machined object, wherein surfaces of the machined object produced by the multiple step-up cuts all lie between the inner limiting surface defined by the offset surface and the outer limiting surface defined by the scallop surface and a decision as to at which height each of the multiple step-up cuts is made is a function of the required non-vertical slope of the finished object at the given height at various locations on the finished object.

Preferably, the function is a function of the smallest slope of the finished object at the given height.

There is further provided in accordance with another preferred em.bodim.ent of the present invention a computer numerically controlled milling machine for fabricating a machined object from a workpiece having a Z-axis, the machined object being configured to facilitate subsequent finishing into a finished object, the computer numerically controlled milling machine including a controller operative for defining a surface of the finished object, defining an offset surface, the offset surface being outside the surface of the finished object and separated therefrom by an offset distance, the offset surface defining an inner limiting surface of the machined object, defining a scallop surface, the scallop surface being outside the offset surface and separated therefrom by a scallop distance, the scallop surface defining an outer limiting surface of the machined object, calculating a tool path for the computer numerically controlled milling machine which produces multiple step-up cuts in the workpiece at multiple heights along the Z-axis, the multiple step up cuts in the

workpiece resulting in the machined object, wherein surfaces of the machined object produced by the multiple step-up cuts all lie between the inner limiting surface defined by the offset surface and the outer limiting surface defined by the scallop surface and the number of multiple step-up cuts in the workpiece at multiple heights along the Z-axis and the areas cut in each of the multiple step-up cuts are selected so as to generally minimize the amount of workpiece material that is removed from the workpiece during the cuts while ensuring that the surfaces of the machined object produced by the multiple step-up cuts all lie between the inner limiting surface defined by the offset surface and the outer limiting surface defined by the scallop surface and directing a computer controlled machine tool along the tool path.

There is still further provided in accordance with yet another preferred em.bodim.ent of the present invention a computer numerically controlled milling machine for fabricating a machined object from a workpiece having a Z-axis, the machined object being configured to facilitate subsequent finishing into a finished object, the computer numerically controlled milling machine including a controller operative for defining a surface of the finished object, defining an offset surface, the offset surface being outside the surface of the finished object and separated therefrom by an offset distance, the offset surface defining an inner limiting surface of the machined object, defining a scallop surface, the scallop surface being outside the offset surface and separated therefrom by a scallop distance, the scallop surface defining an outer limiting surface of the machined object, calculating a tool path for the computer numerically controlled milling machine which produces multiple step-up cuts in the workpiece at multiple heights along the Z-axis, the multiple step up cuts in the workpiece resulting in the machined object, wherein surfaces of the machined object produced by the multiple step-up cuts all lie between the inner limiting surface defined by the offset surface and the outer limiting surface defined by the scallop surface and a decision of whether or not to cut the workpiece at a given location at each height of each of the multiple step-up cuts is a function of the required non-vertical slope of the finished object at the given location and directing a computer controlled machine tool along the tool path.

There is even further provided in accordance with still another preferred embodiment of the present invention a computer numerically controlled milling

machine for fabricating a machined object from a workpiece having a Z-axis, the machined object being configured to facilitate subsequent finishing into a finished object, the computer numerically controlled milling machine including a controller operative for defining a surface of the finished object, defining an offset surface, the offset surface being outside the surface of the finished object and separated therefrom by an offset distance, the offset surface defining an inner limiting surface of the machined object, defining a scallop surface, the scallop surface being outside the offset surface and separated therefrom by a scallop distance, the scallop surface defining an outer limiting surface of the machined object, calculating a tool path for the computer numerically controlled milling machine which produces multiple step-up cuts in the workpiece at multiple heights along the Z-axis, the multiple step up cuts in the workpiece resulting in the machined object, wherein surfaces of the machined object produced by the multiple step-up cuts all lie between the inner limiting surface defined by the offset surface and the outer limiting surface defined by the scallop surface and a decision as to at which height each of the multiple step-up cuts is made is a function of the required non-vertical slope of the finished object at the given height at various locations on the finished object and directing a computer controlled machine tool along the tool path.

Preferably, the function is a function of the smallest slope of the finished object at the given height.

in accordance with a preferred embodiment of the present invention the calculating the tool path includes selecting the height of each of the multiple step-up cuts to be the maximum height which ensures that each of the surfaces that are cut at that height lie between the inner limiting surface defined by the offset surface and the outer limiting surface defined by the scallop surface.

Preferably, the calculating the tool path includes selecting whether or not to cut the workpiece at a given location at each height of each of the multiple step-up cuts. Additionally or alternatively, the calculating the tool path includes selecting the width of the cut at a given location at each height of each of the multiple step-up cuts.

in accordance with a preferred embodiment of the present invention the tool path includes at least an initial tool path portion which defines an initial cut having vertical walls followed by at least one tool path portion which further machines the

vertical walls of the initial cut into a plurality of stepwise vertical walls which together define the vertical slopes at each of the plurality of surface portions which lie adjacent the initial cut and correspond to the multiple step-up cuts.

Preferably, the calculating the tool path for the computer numerically controlled milling machine includes calculating the height of a step for a collection of mutually azimuthally separated points densely distributed all along a curve representing the intersection of a step forward edge wall with a lower step floor surface. Additionally, the calculating the height of a step for a collection of mutually azimuthally separated points includes for each one of the collection of points, drawing an imaginary vertical line, parallel to the Z-axis to extend through the point and intersect at a scallop curve intersection point with the scallop surface, ascertaining the lowest height of a scallop curve intersection point corresponding to any of the collection of mutually azimuthally separated points and selecting the height for the step as being the lowest height of a scallop curve intersection point corresponding to any of the collection of mutually azimuthally separated points.

In accordance with a preferred embodiment of the present invention the calculating the tool path for the computer numerically controlled milling machine also includes taking an imaginary slice through the workpiece perpendicular to the Z-axis at the height for the step, ascertaining a normal distance between the a point on the imaginary vertical line at the height and the scallop surface and if the normal distance for the one of the collection of points is less than a predetermined scallop tolerance, designating the one of the collection of points as a "good to cut" point.

There is even further provided in accordance with still another preferred embodiment of the present invention an automated computer-implemented apparatus for generating commands for controlling a computer numerically controlled milling machine to fabricate an object from a workpiece, the apparatus including a tool path configuration engine operative for ascertaining the available spindle power of the computer numerically controlled milling machine, automatically selecting, using a computer, a maximum depth and width of cut, which are a function at least of the available spindle power of the computer numerically controlled milling machine and configuring a tool path for a tool relative to the workpiece in which the tool path

includes a plurality of tool path layers whose maximum thickness and width of cut correspond to the maximum depth and width of cut.

There is also provided in accordance with another preferred embodiment of the present in vention a computer numerically controlled milling machine including a controller operative for ascertaining the available spindle power of the computer numerically controlled milling machine, automatically selecting a maximum depth and width of cut, which are a function at least of the available spindle power of the computer numerically controlled milling machine, configuring a tool path for a tool relative to a workpiece in which the tool path includes a plurality of tool path layers whose maximum thickness and width of cut correspond to the maximum depth and width of cut and directing a computer controlled machine tool along the tool path.

Preferably, the automatically selecting also includes varying at least one additional parameter of the milling machine as a function of the available spindle power. Additionally, the at least one additional parameter of the milling machine is at least one of feed speed and rpm.

There is still further provided in accordance with yet a further preferred embodiment of the present invention an automated computer-implemented apparatus for generating commands for controlling a computer numerically controlled milling machine to fabricate an object having a relatively thin wall from a workpiece, the apparatus including a tool path configuration engine operative for automatically selecting, using a computer, a tool path having the following characteristics: initially machining the workpiece at first maximum values of cutting depth, cutting width, cutting speed and cutting feed to have a relatively thick wall at the location of an intended relatively thin wall, reducing the height of the relatively thick wall to the intended height of the intended relatively thin wall; and thereafter reducing the thickness of the thick wall by machining the workpiece at second maximum values of cutting depth, cutting width, cutting speed and cutting feed, at least one of the second maximum values being less than a corresponding one of the first maximum values.

There is further provided in accordance with yet another preferred embodiment of the present invention a computer numerically controlled milling machine for fabricating an object having a relatively thin wall from a workpiece, the computer numerically controlled milling machine including a controller operative for automatically selecting a tool path having the following characteristics: initially machining the workpiece at first maximum values of cutting depth, cutting width, cutting speed and cutting feed to have a relatively thick wall at the location of an intended relatively thin wall, reducing the height of the relatively thick wall to the intended height of the intended relatively thin wall and thereafter reducing the thickness of the thick wall by machining the workpiece at second maximum values of cutting depth, cutting width, cutting speed and cutting feed, at least one of the second maximum values being less than a corresponding one of the first maximum values and directing a computer controlled machine tool along the tool path.

There is also provided in accordance with another preferred embodiment of the present invention an automated computer-implemented apparatus for generating commands for controlling a computer numerically controlled milling machine to fabricate an object, the apparatus including a tool path configuration engine operative for ascertaining the extent of tool overhang of a tool being used in the computer numerically controlled milling machine, automatically selecting, using a computer, a tool path which is a function of the tool overhang, the tool path having the following characteristics: for a first tool overhang selecting a tool path having first maximum values of cutting depth, cutting width, cutting speed and cutting feed and for a second tool overhang which is greater than the first tool overhang, selecting a tool path having second maximum values of cutting depth, cutting width, cutting speed and cutting feed, at least one of the second maximum values being less than a corresponding one of the first maximum values.

There is further provided in accordance with yet another preferred embodiment of the present invention a computer numerically controlled milling machine for machining a workpiece, the computer numerically controlled milling machine including a controller operative for ascertaining the extent of tool overhang of a tool being used in the computer numerically controlled milling machine, automatically selecting a tool path which is a function of the tool overhang, the tool path having the following characteristics: for a first tool overhang selecting a tool path having first maximum values of cutting depth, cutting width, cutting speed and cutting feed, for a second tool overhang which is greater than the first tool overhang, selecting a tool path having second maximum values of cutting depth, cutting width, cutting speed and

cutting feed, at least one of the second maximum values being less than a corresponding one of the first maximum values and directing the tool along the tool path.

There is further provided in accordance with yet another preferred embodiment of the present invention an automated computer-implemented apparatus for generating commands for controlling a computer numerically controlled milling machine to fabricate an object having a semi-open region, the apparatus including a tool path configuration engine operative for estimating, using a computer, a first machining time for machining the semi-open region using a generally trichoidal type tool path, estimating, using a computer, a second machining time for machining the semi-open region using a generally spiral type tool path and automatically selecting, using a computer, a tool path type having a shorter machining time.

There is still further provided in accordance with yet a further preferred embodiment of the present invention a computer numerically controlled milling machine for fabricating an object having a semi-open region from a workpiece, the computer numerically controlled milling machine including a controller operative for estimating a first machining time for machining the semi-open region using a generally trichoidal type tool path, estimating a second machining time for machining the semi-open region using a generally spiral type tool path, automatically selecting a tool path type having a shorter machining time and directing a computer controlled machine tool along the tool path type having a shorter machining time.

Preferably, the generally spiral type tool path is characterized in that it includes: an initial spiral type tool path portion characteristic of machining a closed region, included within the semi-open region and having a relatively thick wall separating at least one side thereof from an open edge of the semi-open region and a plurality of tool paths suitable for removal of the relatively thick wall.

In accordance with a preferred embodiment of the present invention the plurality of tool paths are suitable for cutting mutually spaced relatively narrow channels in the thick wall, thereby defining a plurality of thick wall segments and thereafter removing the plurality of thick wall segments. Additionally, the plurality of tool paths include spiral tool paths suitable for removing the plurality of thick wall segments.

CLAIMS

1. An automated computer- implemented method for generating commands for controlling a computer numerically controlled milling machine to fabricate a machined object from a workpiece having a Z-axis, said machined object being configured to facilitate subsequent finishing into a finished object, the method comprising:

defining a surface of said finished object;

defining an offset surface, said offset surface being outside said surface of said finished object and separated therefrom by an offset distance, said offset surface defining an inner limiting surface of said machined object;

defining a scallop surface, said scallop surface being outside said offset surface and separated therefrom by a scallop distance, said scallop surface defining an outer limiting surface of said machined object; and

calculating a tool path for said computer numerically controlled milling machine which produces multiple step-up cuts in said workpiece at multiple heights along said Z-axis, said multiple step up cuts in said workpiece resulting in said machined object, wherein:

surfaces of said machined object produced by said multiple step-up cuts all lie between said inner limiting surface defined by said offset surface and said outer limiting surface defined by said scallop surface; and

the number of multiple step -up cuts in said workpiece at multiple heights along said Z-axis and the areas cut in each of said multiple step-up cuts are selected so as to generally minimize the amount of workpiece material that is removed from said workpiece during said cuts while ensuring that said surfaces of said machined object produced by said multiple step-up cuts all lie between said inner limiting surface defined by said offset surface and said outer limiting surface defined by said scallop surface.

2. An automated computer-implemented method for generating commands for controlling a computer numerically controlled milling machine according to claim 1 and wherein said calculating said tool path includes selecting the height of each of said multiple step-up cuts to be the maximum height which ensures that each of the surfaces that are cut at that height lie between said inner limiting surface defined by said offset surface and said outer limiting surface defined by said scallop surface.

3. An automated computer- implemented method for generating commands for controlling a computer numerically controlled milling machine according to claim 1 and wherein said calculating said tool path includes selecting whether or not to cut said workpiece at a given location at each height of each of said multiple step-up cuts.

4. An automated computer- implemented method for generating commands for controlling a computer numerically controlled milling machine according to claim 1 and wherein said calculating said tool path includes selecting the width of the cut at a given location at each height of each of said multiple step-up cuts.

5. An automated computer- implemented method for generating commands for controlling a computer numerically controlled milling machine according to claim 1 and wherein said tool path includes at least an initial tool path portion which defines an initial cut having vertical walls followed by at least one tool path portion which further machines said vertical walls of said initial cut into a plurality of stepwise vertical walls which together define said vertical slopes at each of said plurality of surface portions which lie adjacent said initial cut and correspond to said multiple step-up cuts.

6. An automated computer- implemented method for generating commands for controlling a computer numerically controlled milling machine according to claim 1 and wherein said calculating said tool path for said computer numerically controlled milling machine comprises calculating the height of a step for a collection of mutually azimuthally separated points densely distributed all along a curve representing the intersection of a step forward edge wall with a lower step floor surface.

7. An automated computer- implemented method for generating commands for controlling a computer numerically controlled milling machine according to claim 6 and wherein said calculating the height of a step for a collection of mutually azimuthally separated points includes:

for each one of said collection of points, drawing an imaginary vertical line, parallel to said Z-axis to extend through said point and intersect at a scallop curve intersection point with said scallop surface;

ascertaining the lowest height of a scallop curve intersection point corresponding to any of said collection of mutually azimuthally separated points; and selecting said height for said step as being said lowest height of a scallop curve intersection point corresponding to any of said collection of mutually azimuthally separated points.

8. An automated computer- implemented method for generating commands for controlling a computer numerically controlled milling machine according to claim 7 and also comprising:

taking an imaginary slice through said workpiece perpendicular to said Z-axis at said height for said step;

ascertaining a normal distance between the a point on said imaginary vertical line at said height and said scallop surface; and

if said normal distance for said one of said collection of points is less than a predetermined scallop tolerance, designating said one of said collection of points as a "good to cut" point.

9. An automated computer- implemented method for generating commands for controlling a computer numerically controlled milling machine to fabricate a machined object from a workpiece having a Z-axis, said machined object being configured to facilitate subsequent finishing into a finished object, the method comprising:

defining a surface of said finished object;

defining an offset surface, said offset surface being outside said surface of said finished object and separated therefrom by an offset distance, said offset surface defining an inner limiting surface of said machined object;

defining a scallop surface, said scallop surface being outside said offset surface and separated therefrom by a scallop distance, said scallop surface defining an outer limiting surface of said machined object; and

calculating a tool path for said computer numerically controlled milling machine which produces multiple step-up cuts in said workpiece at multiple heights along said Z-axis, said multiple step up cuts in said workpiece resulting in said machined object, wherein:

surfaces of said machined object produced by said multiple step-up cuts all lie between said inner limiting surface defined by said offset surface and said outer limiting surface defined by said scallop surface; and

a decision of whether or not to cut said workpiece at a given location at each height of each of said multiple step-up cuts is a function of the required non-vertical slope of said finished object at said given location.

10. An automated computer-implemented method for generating commands for controlling a computer numerically controlled milling machine according to claim 9 and wherein said calculating said tool path includes selecting the height of each of said multiple step-up cuts to be the maximum height which ensures that each of the surfaces that are cut at that height lie between said inner limiting surface defined by said offset surface and said outer limiting surface defined by said scallop surface.

11. An automated computer- implemented method for generating commands for controlling a computer numerically controlled milling machine according to claim 9 and wherein said calculating said tool path includes selecting whether or not to cut said workpiece at a given location at each height of each of said multiple step-up cuts.

12. An automated computer-implemented method for generating commands for controlling a computer numerically controlled milling machine according to claim 9 and wherein said calculating said tool path includes selecting the width of the cut at a given location at each height of each of said multiple step-up cuts.

13. An automated computer- implemented method for generating commands for controlling a computer numerically controlled milling machine according to claim 9 and wherein said tool path includes at least an initial tool path portion which defines an initial cut having vertical walls followed by at least one tool path portion which further machines said vertical walls of said initial cut into a plurality of stepwise vertical walls which together define said vertical slopes at each of said plurality of surface portions which lie adjacent said initial cut and correspond to said multiple step-up cuts.

14. An automated computer- implemented method for generating commands for controlling a computer numerically controlled milling machine according to claim 9 and wherein said calculating said tool path for said computer numerically controlled milling machine comprises calculating the height of a step for a collection of mutually azimuthally separated points densely distributed all along a curve representing the intersection of a step forward edge wall with a lower step floor surface.

15. An automated computer- implemented method for generating commands for controlling a computer numerically controlled milling machine according to claim

14 and wherein said calculating the height of a step for a collection of mutually azimuthally separated points includes:

for each one of said collection of points, drawing an imaginary vertical line, parallel to said Z-axis to extend through said point and intersect at a scallop curve intersection point with said scallop surface;

ascertaining the lowest height of a scallop curve intersection point corresponding to any of said collection of mutually azimuthally separated points; and selecting said height for said step as being said lowest height of a scallop curve intersection point corresponding to any of said collection of mutually azimuthally separated points.

16. An automated computer- implemented method for generating commands for controlling a computer numerically controlled milling machine according to claim

15 and also comprising:

taking an imaginary slice through said workpiece perpendicular to said Z-axis at said height for said step;

ascertaining a normal distance between the a point on said imaginary vertical line at said height and said scallop surface; and

if said normal distance for said one of said collection of points is less than a predetermined scallop tolerance, designating said one of said collection of points as a "good to cut" point.

17. An automated computer- implemented method for generating commands for controlling a computer numerically controlled milling machine to fabricate a machined object from a workpiece having a Z-axis, said machined object being configured to facilitate subsequent finishing into a finished object, the method comprising:

defining a surface of said finished object;

defining an offset surface, said offset surface being outside said surface of said finished object and separated therefrom by an offset distance, said offset surface defining an inner limiting surface of said machined object;

defining a scallop surface, said scallop surface being outside said offset surface and separated therefrom by a scallop distance, said scallop surface defining an outer limiting surface of said machined object; and

calculating a tool path for said computer numerically controlled milling machine which produces multiple step-up cuts in said workpiece at multiple heights along said Z-axis, said multiple step up cuts in said workpiece resulting in said machined object, wherein:

surfaces of said machined object produced by said multiple step-up cuts all lie between said inner limiting surface defined by said offset surface and said outer limiting surface defined by said scallop surface; and

a decision as to at which height each of said multiple step -up cuts is made is a function of the required non-vertical slope of said finished object at said given height at various locations on said finished object.

18. An automated computer- implemented method for generating commands for controlling a computer numerically controlled milling machine according to claim 17 and wherein said function is a function of the smallest slope of said finished object at said given height.

19. An automated computer- implemented method for generating commands for controlling a computer numerically controlled milling machine according to claim 17 and wherein said calculating said tool path includes selecting the height of each of said multiple step-up cuts to be the maximum height which ensures that each of the surfaces that are cut at that height lie between said inner limiting surface defined by said offset surface and said outer limiting surface defined by said scallop surface.

20. An automated computer-implemented method for generating commands for controlling a computer numerically controlled milling machine according to claim 17 and wherein said calculating said tool path includes selecting whether or not to cut said workpiece at a given location at each height of each of said multiple step-up cuts.

21. An automated computer- implemented method for generating commands for controlling a computer numerically controlled milling machine according to claim 17 and wherein said calculating said tool path includes selecting the width of the cut at a given location at each height of each of said multiple step-up cuts.

22. An automated computer-implemented method for generating commands for controlling a computer numerically controlled milling machine according to claim 17 and wherein said tool path includes at least an initial tool path portion which defines an initial cut having vertical walls followed by at least one tool path portion which further machines said vertical walls of said initial cut into a plurality of stepwise vertical walls which together define said vertical slopes at each of said plurality of surface portions which lie adjacent said initial cut and correspond to said multiple step-up cuts.

23. An automated computer- implemented method for generating commands for controlling a computer numerically controlled milling machine according to claim

17 and wherein said calculating said tool path for said computer numerically controlled milling machine comprises calculating the height of a step for a collection of mutually azimuthally separated points densely distributed all along a curve representing the intersection of a step forward edge wall with a lower step floor surface.

24. An automated computer- implemented method for generating commands for controlling a computer numerically controlled milling machine according to claim

23 and wherein said calculating the height of a step for a collection of mutually azimuthally separated points includes:

for each one of said collection of points, drawing an imaginary vertical line, parallel to said Z-axis to extend through said point and intersect at a scallop curve intersection point with said scallop surface;

ascertaining the lowest height of a scallop curve intersection point corresponding to any of said collection of mutually azimuthally separated points; and selecting said height for said step as being said lowest height of a scallop curve intersection point corresponding to any of said collection of mutually azimuthally separated points.

25. An automated computer- implemented method for generating commands for controlling a computer numerically controlled milling machine according to claim

24 and also comprising:

taking an imaginary slice through said workpiece perpendicular to said Z-axis at said height for said step;

ascertaining a normal distance between the a point on said imaginary vertical line at said height and said scallop surface; and

if said normal distance for said one of said collection of points is less than a predetermined scallop tolerance, designating said one of said collection of points as a "good to cut" point.

26. An automated computer-implemented method for generating commands for controlling a computer numerically controlled milling machine to fabricate an object from a workpiece, the method comprising:

ascertaining the available spindle power of said computer numerically controlled milling machine;

automatically selecting, using a computer, a maximum depth and width of cut, which are a function at least of said available spindle power of said computer numerically controlled milling machine; and

configuring a tool path for a tool relative to said workpiece in which said tool path comprises a plurality of tool path layers whose maximum thickness and width of cut correspond to said maximum depth and width of cut.

27. An automated computer- implemented method for generating commands for controlling a computer numerically controlled milling machine according to claim

26 and also comprising varying at least one additional parameter of said milling machine as a function of said available spindle power.

28. An automated computer- implemented method for generating commands for controlling a computer numerically controlled milling machine according to claim

27 and wherein said at least one additional parameter of said milling machine is at least one of feed speed and rpm.

29. An automated computer- implemented method for generating commands for controlling a computer numerically controlled milling machine to fabricate an object having a relatively thin wall from a workpiece, the method comprising:

automatically selecting, using a computer, a tool path having the following characteristics:

initially machining said workpiece at first maximum values of cutting depth, cutting width, cutting speed and cutting feed to have a relatively thick wall at the location of an intended relatively thin wall;

reducing the height of the relatively thick wall to the intended height of the intended relatively thin wall; and thereafter

reducing the thickness of the thick wall by machining said workpiece at second maximum values of cutting depth, cutting width, cutting speed and cutting feed, at least one of said second maximum values being less than a corresponding one of said first maximum values.

30. An automated computer-implemented method for generating commands for controlling a computer numerically controlled milling machine to fabricate an object, the method comprising:

ascertaining the extent of tool overhang of a tool being used in said computer numerically controlled milling machine;

automatically selecting, using a computer, a tool path which is a function of said tool overhang, said tool path having the following characteristics:

for a first tool overhang selecting a tool path having first maximum values of cutting depth, cutting width, cutting speed and cutting feed; and

for a second tool overhang which is greater than said first tool overhang, selecting a tool path having second maximum values of cutting depth, cutting width, cutting speed and cutting feed, at least one of said second maximum values being less than a corresponding one of said first maximum values.

31. An automated computer- implemented method for generating commands for controlling a computer numerically controlled milling machine to fabricate an object having a semi-open region, the method comprising:

estimating, using a computer, a first machining time for machining said semi-open region using a generally trichoidal type tool path;

estimating, using a computer, a second machining time for machining said semi-open region using a generally spiral type tool path; and

automatically selecting, using a computer, a tool path type having a shorter machining time.

32. An automated computer-implemented method for generating commands for controlling a computer numerically controlled milling machine to fabricate an object having a semi-open region according to claim 31 and wherein said generally spiral type tool path is characterized in that it includes:

an initial spiral type tool path portion characteristic of machining a closed region, included within said semi-open region and having a relatively thick wall separating at least one side thereof from an open edge of said semi-open region; and a plurality of tool paths suitable for removal of said relatively thick wall.

33. An automated computer- implemented method for generating commands for controlling a computer numerically controlled milling machine to fabricate an object having a semi-open region according to claim 32 and wherein said plurality of tool paths are suitable for cutting mutually spaced relatively narrow channels in said thick wall, thereby defining a plurality of thick wall segments and thereafter removing the plurality of thick wall segments.

34. An automated computer-implemented method for generating commands for controlling a computer numerically controlled milling machine to fabricate an object having a semi-open region according to claim 33 and wherein said plurality of tool paths include spiral tool paths suitable for removing the plurality of thick wall segments.

35. An automated computer- implemented method for generating commands for controlling a computer numerically controlled milling machine to fabricate an object having a channel open at both its ends and including an intermediate narrowest portion, the method including automatically selecting, using a computer, a tool path type having first and second tool path portions, each starting at a different open end of said channel, said first and second tool path portions meeting at said intermediate narrowest portion.

36. An automated computer- implemented method for generating commands for controlling a computer numerically controlled milling machine to fabricate an object which fabrication involves cutting a workpiece at at least first and second different maximum depths of cut, wherein said first maximum depth of cut is greater than said second maximum depth of cut the method including automatically selecting, using a computer, at least first and second tool paths having corresponding first and second maximum values of cutting width, cutting speed and cutting feed, at least one of said second maximum values being greater than a corresponding one of said first maximum values.

37. An automated computer- implemented method for generating commands for controlling a computer numerically controlled milling machine according to claim

36 and wherein said automatically selecting comprises adjusting said first and second maximum values of cutting width, cutting speed and cutting feed to ensure that the mechanical load experienced by a milling tool is at a generally constant optimized value.

38. An automated computer- implemented method for generating commands for controlling a computer numerically controlled milling machine to fabricate an object, wherein fabrication of the object involves calculating multiple tool paths requiring tool repositioning therebetween along a selectable repositioning path, the method comprising:

estimating, using a computer, a first repositioning time for a first repositioning path which includes travel in a clearance plane above a workpiece;

estimating, using a computer, a second repositioning time for a second repositioning path which does not include tool travel in said clearance plane; and

automatically selecting, using a computer, a repositioning path having a shortest repositioning time.

39. An automated computer- implemented method for generating commands for controlling a computer numerically controlled milling machine to fabricate an object according to claim 38 and wherein said second repositioning path is automatically selected by said computer from among possible multiple repositioning paths which do not include tool travel in said clearance plane on the basis of shortest repositioning time.

40. An automated computer-implemented method for generating commands for controlling a computer numerically controlled milling machine to fabricate an object according to claim 39 and wherein said multiple repositioning paths include

repositioning paths which require raising of said tool and repositioning paths which do not require raising of said tool.

41. An automated computer- implemented apparatus for generating commands for controlling a computer numerically controlled milling machine to fabricate a machined object from a workpiece having a Z-axis, said machined object being configured to facilitate subsequent finishing into a finished object, the apparatus comprising a tool path configuration engine operative for:

defining a surface of said finished object;

defining an offset surface, said offset surface being outside said surface of said finished object and separated therefrom by an offset distance, said offset surface defining an inner limiting surface of said machined object;

defining a scallop surface, said scallop surface being outside said offset surface and separated therefrom by a scallop distance, said scallop surface defining an outer limiting surface of said machined object; and

calculating a tool path for said computer numerically controlled milling machine which produces multiple step-up cuts in said workpiece at multiple heights along said Z-axis, said multiple step up cuts in said workpiece resulting in said machined object, wherein:

surfaces of said machined object produced by said multiple step-up cuts all lie between said inner limiting surface defined by said offset surface and said outer limiting surface defined by said scallop surface; and

the number of multiple step -up cuts in said workpiece at multiple heights along said Z-axis and the areas cut in each of said multiple step-up cuts are selected so as to generally minimize the amount of workpiece material that is removed from said workpiece during said cuts while ensuring that said surfaces of said machined object produced by said multiple step-up cuts all lie between said inner limiting surface defined by said offset surface and said outer limiting surface defined by said scallop surface.

42. An automated computer-implemented apparatus for generating commands for controlling a computer numerically controlled milling machine to

fabricate a machined object from a workpiece having a Z-axis, said machined object being configured to facilitate subsequent finishing into a finished object, the apparatus comprising a tool path configuration engine operative for:

defining a surface of said finished object;

defining an offset surface, said offset surface being outside said surface of said finished object and separated therefrom by an offset distance, said offset surface defining an inner limiting surface of said machined object;

defining a scallop surface, said scallop surface being outside said offset surface and separated therefrom by a scallop distance, said scallop surface defining an outer limiting surface of said machined object; and

calculating a tool path for said computer numerically controlled milling machine which produces multiple step-up cuts in said workpiece at multiple heights along said Z-axis, said multiple step up cuts in said workpiece resulting in said machined object, wherein:

surfaces of said machined object produced by said multiple step-up cuts all lie between said inner limiting surface defined by said offset surface and said outer limiting surface defined by said scallop surface; and

a decision of whether or not to cut said workpiece at a given location at each height of each of said multiple step-up cuts is a function of the required non-vertical slope of said finished object at said given location.

43. An automated computer- implemented apparatus for generating commands for controlling a computer numerically controlled milling machine to fabricate a machined object from a workpiece having a Z-axis, said machined object being configured to facilitate subsequent finishing into a finished object, the apparatus comprising a tool path configuration engine operative for:

defining a surface of said finished object;

defining an offset surface, said offset surface being outside said surface of said finished object and separated therefrom by an offset distance, said offset surface defining an inner limiting surface of said machined object;

defining a scallop surface, said scallop surface being outside said offset surface and separated therefrom by a scallop distance, said scallop surface defining an outer limiting surface of said machined object; and

calculating a tool path for said computer numerically controlled milling machine which produces multiple step-up cuts in said workpiece at multiple heights along said Z-axis, said multiple step up cuts in said workpiece resulting in said machined object, wherein:

surfaces of said machined object produced by said multiple step-up cuts all lie between said inner limiting surface defined by said offset surface and said outer limiting surface defined by said scallop surface; and

a decision as to at which height each of said multiple step -up cuts is made is a function of the required non-vertical slope of said finished object at said given height at various locations on said finished object.

44. A machined object fabricated from a workpiece having a Z-axis, said machined object being configured to facilitate subsequent finishing into a finished object, using a computer numerically controlled milling machine by:

defining a surface of said finished object;

defining an offset surface, said offset surface being outside said surface of said finished object and separated therefrom by an offset distance, said offset surface defining an inner limiting surface of said machined object;

defining a scallop surface, said scallop surface being outside said offset surface and separated therefrom by a scallop distance, said scallop surface defining an outer limiting surface of said machined object;

calculating a tool path for said computer numerically controlled milling machine which produces multiple step-up cuts in said workpiece at multiple heights along said Z-axis, said multiple step up cuts in said workpiece resulting in said machined object, wherein:

surfaces of said machined object produced by said multiple step-up cuts all lie between said inner limiting surface defined by said offset surface and said outer limiting surface defined by said scallop surface; and

the number of multiple step-up cuts in said workpiece at multiple heights along said Z-axis and the areas cut in each of said multiple step-up cuts are selected so as to generally minimize the amount of workpiece material that is removed from said workpiece during said cuts while ensuring that said surfaces of said machined object produced by said multiple step-up cuts all lie between said inner limiting surface defined by said offset surface and said outer limiting surface defined by said scallop surface; and

directing a computer controlled machine tool along said tool path.

45. A machined object according to claim 44 and wherein said calculating said tool path includes selecting the height of each of said multiple step-up cuts to be the maximum height which ensures that each of the surfaces that are cut at that height lie between said inner limiting surface defined by said offset surface and said outer limiting surface defined by said scallop surface.

46. A machined object according to claim 44 and wherein said calculating said tool path includes selecting whether or not to cut said workpiece at a given location at each height of each of said multiple step-up cuts.

47. A machined object according to claim 44 and wherein said calculating said tool path includes selecting the width of the cut at a given location at each height of each of said multiple step -up cuts.

48. A machined object according to claim 44 and wherein said tool path includes at least an initial tool path portion which defines an initial cut having vertical walls followed by at least one tool path portion which further machines said vertical walls of said initial cut into a plurality of stepwise vertical walls which together define said vertical slopes at each of said plurality of surface portions which lie adjacent said initial cut and correspond to said multiple step-up cuts.

49. A machined object according to claim 44 and wherein said calculating said tool path for said computer numerically controlled milling machine comprises

calculating the height of a step for a collection of mutually azimuthally separated points densely distributed all along a curve representing the intersection of a step forward edge wall with a lower step floor surface.

50. A machined object according to claim 49 and wherein said calculating the height of a step for a collection of mutually azimuthally separated points includes:

for each one of said collection of points, drawing an imaginary vertical line, parallel to said Z-axis to extend through said point and intersect at a scallop curve intersection point with said scallop surface;

ascertaining the lowest height of a scallop curve intersection point corresponding to any of said collection of mutually azimuthally separated points; and selecting said height for said step as being said lowest height of a scallop curve intersection point corresponding to any of said collection of mutually azimuthally separated points.

51. A machined object according to claim 50 and said calculating said tool path also comprises:

taking an imaginary slice through said workpiece perpendicular to said Z-axis at said height for said step;

ascertaining a normal distance between the a point on said imaginary vertical line at said height and said scallop surface; and

if said normal distance for said one of said collection of points is less than a predetermined scallop tolerance, designating said one of said collection of points as a "good to cut" point.

52. A machined object fabricated from a workpiece having a Z-axis, said machined object being configured to facilitate subsequent finishing into a finished object, using a computer numerically controlled milling machine by:

defining a surface of said finished object;

defining an offset surface, said offset surface being outside said surface of said finished object and separated therefrom by an offset distance, said offset surface defining an inner limiting surface of said machined object;

defining a scallop surface, said scallop surface being outside said offset surface and separated therefrom by a scallop distance, said scallop surface defining an outer limiting surface of said machined object;

calculating a tool path for said computer numerically controlled milling machine which produces multiple step-up cuts in said workpiece at multiple heights along said Z-axis, said multiple step up cuts in said workpiece resulting in said machined object, wherein:

surfaces of said machined object produced by said multiple step-up cuts all lie between said inner limiting surface defined by said offset surface and said outer limiting surface defined by said scallop surface; and

a decision of whether or not to cut said workpiece at a given location at each height of each of said multiple step-up cuts is a function of the required non-vertical slope of said finished object at said given location; and

directing a computer controlled machine tool along said tool path.

53. A machined object according to claim 52 and wherein said calculating said tool path includes selecting the height of each of said multiple step-up cuts to be the maximum height which ensures that each of the surfaces that are cut at that height lie between said inner limiting surface defined by said offset surface and said outer limiting surface defined by said scallop surface.

54. A machined object according to claim 52 and wherein said calculating said tool path includes selecting whether or not to cut said workpiece at a given location at each height of each of said multiple step-up cuts.

55. A machined object according to claim 52 and wherein said calculating said tool path includes selecting the width of the cut at a given location at each height of each of said multiple step -up cuts.

56. A machined object according to claim 52 and wherein said tool path includes at least an initial tool path portion which defines an initial cut having vertical walls followed by at least one tool path portion which further machines said vertical

walls of said initial cut into a plurality of stepwise vertical walls which together define said vertical slopes at each of said plurality of surface portions which lie adjacent said initial cut and correspond to said multiple step-up cuts.

57. A machined object according to claim 52 and wherein said calculating said tool path for said computer numerically controlled milling machine comprises calculating the height of a step for a collection of mutually azimuthally separated points densely distributed all along a curve representing the intersection of a step forward edge wall with a lower step floor surface.

58. A machined object according to claim 52 and wherein said calculating the height of a step for a collection of mutually azimuthally separated points includes:

for each one of said collection of points, drawing an imaginary vertical line, parallel to said Z-axis to extend through said point and intersect at a scallop curve intersection point with said scallop surface;

ascertaining the lowest height of a scallop curve intersection point corresponding to any of said collection of mutually azimuthally separated points; and selecting said height for said step as being said lowest height of a scallop curve intersection point corresponding to any of said collection of mutually azimuthally separated points.

59. A machined object according to claim 58 and wherein said calculating said tool path also comprises:

taking an imaginary slice through said workpiece perpendicular to said Z-axis at said height for said step;

ascertaining a normal distance between the a point on said imaginary vertical line at said height and said scallop surface; and

if said normal distance for said one of said collection of points is less than a predetermined scallop tolerance, designating said one of said collection of points as a "good to cut" point.

60. A machined object fabricated from a workpiece having a Z-axis, said machined object being configured to facilitate subsequent finishing into a finished object, using a computer numerically controlled milling machine by:

defining a surface of said finished object;

defining an offset surface, said offset surface being outside said surface of said finished object and separated therefrom by an offset distance, said offset surface defining an inner limiting surface of said machined object;

defining a scallop surface, said scallop surface being outside said offset surface and separated therefrom by a scallop distance, said scallop surface defining an outer limiting surface of said machined object;

calculating a tool path for said computer numerically controlled milling machine which produces multiple step-up cuts in said workpiece at multiple heights along said Z-axis, said multiple step up cuts in said workpiece resulting in said machined object, wherein:

surfaces of said machined object produced by said multiple step-up cuts all lie between said inner limiting surface defined by said offset surface and said outer limiting surface defined by said scallop surface; and

a decision as to at which height each of said multiple step -up cuts is made is a function of the required non-vertical slope of said finished object at said given height at various locations on said finished object; and

directing a computer controlled machine tool along said tool path.

61. A machined object according to claim 60 and wherein said function is a function of the smallest slope of said finished object at said given height.

62. A machined object according to claim 60 and wherein said calculating said tool path includes selecting the height of each of said multiple step-up cuts to be the maximum height which ensures that each of the surfaces that are cut at that height lie between said inner limiting surface defined by said offset surface and said outer limiting surface defined by said scallop surface.

63. A machined object according to claim 60 and wherein said calculating said tool path includes selecting whether or not to cut said workpiece at a given location at each height of each of said multiple step-up cuts.

64. A machined object according to claim 60 and wherein said calculating said tool path includes selecting the width of the cut at a given location at each height of each of said multiple step -up cuts.

65. A machined object according to claim 60 and wherein said tool path includes at least an initial tool path portion which defines an initial cut having vertical walls followed by at least one tool path portion which further machines said vertical walls of said initial cut into a plurality of stepwise vertical walls which together define said vertical slopes at each of said plurality of surface portions which lie adjacent said initial cut and correspond to said multiple step-up cuts.

66. A machined object according to claim 60 and wherein said calculating said tool path for said computer numerically controlled milling machine comprises calculating the height of a step for a collection of mutually azimuthally separated points densely distributed all along a curve representing the intersection of a step forward edge wall with a lower step floor surface.

67. A machined object according to claim 66 and wherein said calculating the height of a step for a collection of mutually azimuthally separated points includes:

for each one of said collection of points, drawing an imaginary vertical line, parallel to said Z-axis to extend through said point and intersect at a scallop curve intersection point with said scallop surface;

ascertaining the lowest height of a scallop curve intersection point corresponding to any of said collection of mutually azimuthally separated points; and selecting said height for said step as being said lowest height of a scallop curve intersection point corresponding to any of said collection of mutually azimuthally separated points.

68. A machined object according to claim 67 and said calculating said tool path also comprises:

taking an imaginary slice through said workpiece perpendicular to said Z-axis at said height for said step;

ascertaining a normal distance between the a point on said imaginary vertical line at said height and said scallop surface; and

if said normal distance for said one of said collection of points is less than a predetermined scallop tolerance, designating said one of said collection of points as a "good to cut" point.

69. A machined object having a relatively thin wall fabricated from a workpiece using a computer numerically controlled milling machine by:

automatically selecting a tool path having the following characteristics: initially machining said workpiece at first maximum values of cutting depth, cutting width, cutting speed and cutting feed to have a relatively thick wall at the location of an intended relatively thin wall;

reducing the height of the relatively thick wall to the intended height of the intended relatively thin wall; and thereafter

reducing the thickness of the thick wall by machining said workpiece at second maximum values of cutting depth, cutting width, cutting speed and cutting feed, at least one of said second maximum values being less than a corresponding one of said first maximum values; and

directing a computer controlled machine tool along said tool path.

70. A machined object machined from a workpiece using a computer numerically controlled milling machine by:

ascertaining the extent of tool overhang of a tool being used in said computer numerically controlled milling machine;

automatically selecting a tool path which is a function of said tool overhang, said tool path having the following characteristics:

for a first tool overhang selecting a tool path having first maximum values of cutting depth, cutting width, cutting speed and cutting feed; and

for a second tool overhang which is greater than said first tool overhang, selecting a tool path having second maximum values of cutting depth, cutting width, cutting speed and cutting feed, at least one of said second maximum values being less than a corresponding one of said first maximum values; and

directing said tool along said tool path.

71. A machined object having a semi-open region fabricated from a workpiece using a computer numerically controlled milling machine by:

estimating a first machining time for machining said semi-open region using a generally trichoidal type tool path;

estimating a second machining time for machining said semi-open region using a generally spiral type tool path;

automatically selecting a tool path type having a shorter machining time; and

directing a computer controlled machine tool along said tool path type having a shorter machining time.

72. A machined object having a channel open at both its ends and including an intermediate narrowest portion fabricated using a computer numerically controlled milling machine by:

automatically selecting a tool path type having first and second tool path portions, each starting at a different open end of said channel, said first and second tool path portions meeting at said intermediate narrowest portion; and

directing a computer controlled machine tool along said first and second tool path portions.

73. A machined object, the fabrication of which involves cutting a workpiece at at least first and second different maximum depths of cut, wherein said first maximum depth of cut is greater than said second maximum depth of cut, fabricated using a computer numerically controlled milling machine by:

automatically selecting at least first and second tool paths having corresponding first and second maximum values of cutting width, cutting speed and

cutting feed, at least one of said second maximum values being greater than a corresponding one of said first maximum values; and

directing a computer controlled machine tool along said at least first and second tool paths.