CAD/CAM system and method of generating machining paths for the same

A CAD/CAM system comprises a removal shape extraction section for extracting removal shape data from the defined finish shape data and work shape data, and a machining step generation section for generating a machining step for each machining surface Z height of the removal shape extracted by the removal shape extraction section.

FIELD OF THE INVENTION 
This invention relates to a CAD/CAM system and method of generating 
machining paths for generating machining paths (hereinafter referred to as 
"paths"). More particularly, the invention relates to a CAD/CAM system and 
method of generating machining paths which can generate paths of a 
machining center when a machine tool is moved in radial direction and Z 
direction to define a three-dimensional shape. 
BACKGROUND OF THE INVENTION 
FIG. 23 is a block diagram outlining a conventional CAD/CAM system. The 
system comprises a central processing unit (hereinafter referred to as 
CPU) 1a, which includes a central processor 11 for executing control 
operations for controlling the entire system, a drawing definition section 
12 for defining drawings for removal shape generation, a removal shape 
definition section 13a for defining removal shapes for path generation, a 
machining step definition section 14a for defining machining conditions, 
such as the specifications for coarse and finish machining, cutting extent 
and feed speed of the tool, from defined removal shape data, and a path 
generation section 15 for generating paths according to defined machining 
step data. Also, included is an input unit 2 for inputting force data and 
command data to the CPU, a display unit 3 for graphically displaying 
drawing data, shape data and paths according to the results of operation 
in the CPU, a storage unit 4 for storing program data and results of 
operations in the CPU 1a, and an output unit 5 for outputting the contents 
displayed on the display unit 3 to a printer or the like. 
Now, a method of obtaining a finish shape shown in FIG. 9A by generating 
paths shown in FIGS. 10A-10D to 12A-12C on a work shape shown in FIG. 9B 
with the conventional CAD/CAM system, will be described with reference to 
a drawing element status view of FIG. 13A, a curve status view of FIG. 
13B, removal shape Z direction division status views of FIGS. 14A and 14B, 
removal shape status views of FIGS. 15A-15H, 16A-16H and to 17A-17F, 
initial hole removal shape status views of FIGS. 18A and 18B, a Z 
direction cut extent uniformization status view of FIG. 19, and a flow 
chart of FIG. 23. A longitudinal line area in FIGS. 15A-15H and FIGS. 18A 
and 18B show removed portions, a heavy line area in FIGS. 15A-15H and 
FIGS. 18A and 18B show finish shape portions. 
First, with reference to FIGS. 13A, 13B and 23, lines a1 to a7 shown in 
FIG. 13A are defined by inputting commands for defining the lines a1 to a7 
together with X-Y coordinates of end points t1 to t6 of the lines a1 to 
a7, X-Y coordinates of center points t7 and t8 of the lines a6 and a7 and 
radii r1 and r2 of the lines a6 and a7 from the input unit 2. Also, 
"curves" C0 to C4 shown in FIG. 13B are defined by inputting a command for 
extracting the curve C1 from the lines a1 to a4, a command for extracting 
the curve C2 from the lines a1, a2, a4 and a5, a command for extracting 
the curve C4 from the line a7 and a command for extracting the curve C0 
from the lines a1 to a3 and a5 from the input unit 2 (step S51: drawing 
definition in FIG. 24). 
Then, a removal shape V11 shown in FIG. 15A is defined by inputting a 
command for defining the removal shape V11 from the input unit 2. The 
command would be for performing machining from a machining surface height 
Z0 shown in FIG. 14A to the machining surface height Z1 plus Z direction 
finish margin Cz1, together with the machining surface height Z1 and Z 
direction finish margin Cz1. Also, like the removal shape V11, removal 
shapes V12 to V14 shown in FIGS. 15C-15H, shapes V21 to V24 shown in FIGS. 
16A-16H and shape V31 to V33 shown in FIGS. 17A-17F are defined by 
inputting data of the curves C1 to C4, machining surface heights Z2 to Z4 
and Z direction finish margins Cz2 t Cr3 (step S52: removal shape 
definition in FIG. 4). 
Further, a machining step K11 shown in FIG. 21 is defined by inputting 
several lines from the input unit 2. The input are command for defining 
the machining step K11, a helical or parallel line machining pattern of 
path P11 shown in FIG. 10A generated for the removal shape V11, a radial 
direction cut extent Pr11 shown in FIG. 10A, a Z direction cut extent Pz1 
and radial direction finish margin Cr1 shown in FIG. 19, a Z direction 
finish margin Cz1 shown in FIGS. 14A and 14B and a machining directions 
d11 of the path P11 shown in FIG. 10A. 
Like the machining step K11, machining steps K12 to K14, K22 to K24 and K31 
to K33 are defined by inputting machining patterns of paths P12 to P14 
shown in FIGS. 10A-10D and paths P21 to P24 shown in FIGS. 11A-11D, radial 
direction cut extents Pr12 to Pr14 and Pr21 to Pr24, radial direction 
finish margins Cr2 and Cr3 and machining directions d12 and d13 shown in 
FIGS. 10A-10D and s22 to d24 shown in FIGS. 11A-11D. 
With respect to the coarse machining removal shape V14 shown in FIG. 15G, a 
machining step K1 shown in FIG. 21 is further defined by inputting the X 
and Y coordinates of the machining position H1 of the initial hole removal 
shape I1 shown in FIGS. 18A and 18B, the machining surface height Z2 plus 
Z direction finish margin Cz3 shown in FIG. 15G as the machining surface 
height Z and the machining surface height Z2 plus Z direction finish 
margin Cz2 as the machining surface height Z (step S53: machining step 
definition). 
Then, machining path generation commands for generating the paths P11 to 
P14, P21 to P24 and P31 to P33 from the machining steps K11, K12, K1, K13, 
K14, K21 to K24 and K31 to K33, defined in the step S4a, are input from 
the input unit 2 (step S54: machining path generation commanding). 
The path generation section 15, receiving the above machining path 
generation commands, generates the path P11 for the machining step K11 
according to the radial direction cut extent Pr11, Z direction cut extent 
Pz1 and machining direction d11, designated in the step S4a. Likewise, the 
section 15 successively generates the paths P12, P1, P13, P14, P21 to P24 
and P31 to P33. When it has generated the paths up to the lowest surface Z 
height Z4, it ends the process (step S55: path generation). 
With the conventional CAD/CAM system having the above construction, 
however, it is necessary to define the removal shape by dividing the work 
shape in the radial and Z directions for each machining step. In addition, 
it is necessary for each removal shape to input the radial and Z direction 
cutting extents and finish margins, helical, parallel line or like path 
pattern, machining direction data concerning the path, Z direction 
machining surface height and machining depth concerning the initial hole, 
and offset direction and offset amount of the removal shape contour curve. 
It is time-consuming to input the above shape data and machining data. In 
addition, the optimum input value determination and machining step design 
require skill and thus lead to inferior operation efficiency. 
SUMMARY OF THE INVENTION 
It is an object to provide a CAD/CAM system and a method of generating 
machining paths for the same, in which the work shape is divided according 
to defined work shape data and finish shape data for each of a plurality 
of machining surface Z heights, and removal shapes for machining path 
generation are automatically extracted by effecting a check as to the 
inclusion of machining surface in the radial direction, thus automatically 
generating a machining path for each removal shape and permitting 
operation efficiency improvement. 
According to the invention, there is provided a CAD/CAM system, in which 
each machining path is defined continuously according to defined finish 
shape data, and which comprises removal shape extraction means for 
extracting removal shape data from the defined finish shape data and also 
from work shape data, and machining step generation means for generating 
each machining step for the Z height of the machining surface of reach 
removal shape extracted by the removal shape extraction means. 
The removal shape extraction means includes Z direction division means for 
dividing the work shape in a Z height direction thereof for each machining 
surface Z height of the finish shape between the highest and lowest height 
Z heights in the Z height direction, and contour curve inclusion judgment 
means for specifying a removal shape for each machining surface Z height 
by judging whether the finish shape contour curve corresponding to the 
work shape after the division is included therein in the radial direction. 
The machining step generation means includes machining direction 
determining means for determining a machining direction by removal shape 
division for each of coarse and finish machining steps, machining 
condition determining means for determining machining conditions such as 
cutting extents, feed speed and rpm of tool for each machining step, 
offset direction determining means for determining each finish shape 
contour curve offset direction for each machining step, offset amount 
determining means for determining the contour curve offset amount for each 
machining step, and initial hole determining means for determining the 
position of an initial hole in the machining step. 
The Z direction division means includes extraction division means for 
extracting, in case of a curved finish shape, a horizontal portion of a 
curve representing a section of the removal shape, and dividing the 
removal shape in the Z height direction at the Z height of the horizontal 
portion. 
The machining direction determining means includes determining means for 
effecting machining path direction determination such that if the finish 
shape contour corresponding to a machining step is pond-like, the 
machining path direction is along the finish shape contour, if the contour 
is island-like, the direction is parallel to the longitudinal direction of 
the contour, and if the contour has pond- and island-like portions, the 
direction is along the island-like portion of the contour. 
The offset direction determining means includes determining means for 
automatically determining the offset direction such that if the finish 
shape contour corresponding to the work shape after division is pond-like, 
the offset direction of the contour is directed inwardly of the contour, 
if the contour is island-like, the offset direction is directed outwardly 
of said contour, and if the contour has both pond- and island-like 
portions, the offset direction is directed inwardly of the contour with 
respect to the pond-like portion and inwardly of the contour with respect 
to the island-like portion. 
The offset amount determining means includes determining means for 
determining the amount of tool diameter offsetting of the finish shape 
contour for a machining step such that if the contour is pond-like, the 
offset amount is the sum of the tool diameter and the finish margin, if 
the contour is island-like, the offset amount is the difference between 
the tool diameter and an amount of protruding of the tool, and if the 
contour has pond- and island-like portions, the offset amount is the sum 
of the tool diameter and the finish margin with respect to the pond-like 
portion and the difference between the tool diameter and the amount of 
protruding of the tool with respect to the island-like portion. 
The machining condition determining means determines the machining path 
pattern such that if the finish shape contour corresponding to the 
machining path is pond-like, the machining path is helical, if the contour 
is island-like, the pattern consists of parallel lines, and if the contour 
has pond- and island-like portions, the pattern continuously offsets the 
island-like portion. 
The machining condition determining means includes first uniformizing means 
for uniformizing the Z direction cut extent in each machining step, and 
second uniformizing means for uniformizing the radial direction cut extent 
in each machining step. 
The machining condition determining means includes setting means for 
calling machining conditions, such as the radial and Z direction cut 
extents, radial and Z direction feed speeds and rpm of tool, from an 
optimum machining condition data base registered for each tool according 
to the input tool name or tool identification No. and setting the called 
machining conditions for the pertinent machining step. 
The initial hole determining means includes control means for generating an 
initial hole machining step if the finish shape contour corresponding to 
the machining step is pond-like and not generating any initial hole 
machining step if the contour has pond- and island-like portions. 
According to the invention, there is also provided a method of generating 
machining paths for the CAD/CAM system, which comprises the steps of 
executing drawing definition by executing drawing definition, curve 
definition, finish shape definition and work shape definition, executing 
shape extraction by executing shape division in the Z direction and 
contour curve inclusion check for each removal shape, executing machining 
step generation by executing machining direction determination, machining 
condition determination and initial hole determination, and subsequently 
executing machining path generation. 
In the removal shape extraction means according to the invention, the Z 
direction division means divides the work shape in a Z height direction 
thereof for each machining surface Z height of the finish shape between 
the highest and lowest Z heights in the Z height direction, and the 
contour curve inclusion judgment means judges for each machining surface Z 
height whether the finish shape contour curve corresponding to the work 
shape after the division is included therein in the radial direction. 
In the machining step generation means according to the invention, the 
machining direction determination means a machining direction by effecting 
removal shape division for each of coarse and finish machining steps, the 
machining condition determining means determines machining conditions such 
as cut extents, feed speeds and rpm of tool for each machining step, 
offset direction determining means determines each finish shape contour 
curve offset direction for each machining step, the offset amount 
determining means determines the contour curve offset amount for each 
machining step, and the initial hole determining means determines the 
position of the initial hole in the machining step. 
In the Z direction division means according to the invention, the 
extraction division means extracts, in case of a curved finish shape, a 
horizontal portion in a curve representing a section of the pertinent 
removal shape, and divides the removal shape in the Z height direction at 
the Z height of the horizontal portion. 
The machining direction determining means according to the invention 
effects machining path direction determination such that if the finish 
shape contour corresponding to a machining step is pond-like, the 
machining path direction is along the finish shape contour, if the contour 
is island-like, the direction is parallel to the longitudinal direction of 
the contour, and if the contour has island-like with wall, the direction 
is along the pond-like portion of the contour. 
The offset direction determining means according to the invention 
automatically determines the offset direction such that if the finish 
shape contour corresponding to the work shape after the division is 
pond-like, the offset direction of the contour is directed inwardly of the 
contour, if the contour is island-like, the offset direction is directed 
outwardly of the contour, and if the contour has island-like with wall, 
the offset direction is directed inwardly of the contour with respect to 
the pond-like portion and outwardly of the contour with respect to the 
island-like portion. 
The offset amount determining means according to the invention determines 
the amount of tool diameter offsetting of the finish shape contour for a 
machining step such that if the contour is pond-like, the offset amount is 
the sum of the tool diameter and the finish margin, if the contour is 
island-like, the offset amount is the difference between the tool diameter 
and an amount of protruding of the tool, and if the contour has 
island-like with wall, the offset amount is the sum of the tool diameter 
and the finish margin with respect to the pond-like portion and is the 
difference between the tool diameter and the amount of protruding of the 
tool with respect to the island-like portion. 
The machining condition determining means according to the invention 
determines the machining path pattern such that if the finish shape 
contour corresponding to a machining path is pond-like, the machining path 
pattern is helical, if the contour is island-like, the pattern consists of 
parallel lines, and if the contour has island-like with wall, the pattern 
continuously offset for the island-like portion. 
The machining condition determining means also uniformizes the Z direction 
cut extent in each machining step and also uniformizes the radial 
direction cut extent in each machining step. 
The machining condition determining means further calls machining 
conditions, such as the radial and Z direction cut extents, radial and Z 
direction feed speeds and rpm of tool, from an optimum machining condition 
data base registered for each tool according to the input tool name or 
tool identification No. and sets the called machining conditions for the 
pertinent machining step. 
The initial hole determining means according to the inventions generates an 
initial hole machining step if the finish shape contour corresponding to 
the machining step is pond-like and does not generate any initial hole 
machining step if the contour has pond- and island-like portions. 
As has been described in the foregoing, according to the invention removal 
shapes are generated automatically through division of a given work shape 
at finish surface Z heights of the finish shape. Thus, it is possible to 
dispense with an operation of inputting the removal shapes, which is 
cumbersome and constitutes double operation with respect to the finish 
shape input. In addition, the patterns and directions of paths are 
automatically determined from the generated removal shapes, and also 
optimum machining conditions are determined automatically from machining 
condition data bases. Thus, it is possible to permit easy determination of 
the patterns and directions of paths as well as machining conditions 
without need of any skill unlike the conventional operation of this type. 
Further, with the removal shape extraction means according to the 
invention, the Z direction division means divides the work shape in the Z 
height direction at each machining surface Z height between the top and 
bottom H heights, and the contour curve inclusion judgment means specifies 
the removal shape by checking the radial direction inclusion of the finish 
shape contour curve corresponding to the work shape after the division. 
Thus, it is possible to dispense with the cumbersome operation of 
inputting removal shape obtained by dividing the work shape. 
Further, with the machining step generation means according to the 
invention, the machining direction determining means determines the 
machining direction by dividing the removal shape for each of coarse and 
finish machining steps. Thus, it is possible to save the labor of the 
operation of dividing the removal shape for each of the coarse and finish 
machining steps. In addition, the machining condition determining means 
determines machining conditions such as the cut extent, feed speed and rpm 
of tool for each machining step. Thus, it is possible to determine the 
machining conditions without need of skill. Further, the offset direction 
determining means determines the offset direction of the finish shape 
contour curve for each machining step, while the offset amount determining 
means determines the offset amount with respect to the curve for each 
machining step. It is thus possible to save the labor of inputting the 
offset direction and offset amount with respect to a curve. Further, the 
initial hole determining means automatically determines the initial hole 
position in the machining step. It is thus possible to case the labor of 
calculating and inputting the initial hole machining surface H height as 
the initial hole machining position. 
Further, with the Z direction division means according to the invention, in 
case of a curved finish surface a horizontal portion in a curve 
representing a section of the removal shape is extracted, and the removal 
shape is divided in the Z height direction at the Z height of the 
horizontal portion. It is thus possible to dispense with the cumbersome 
operation of dividing a curved removal shape in the Z height direction for 
each horizontal portion of the curve representing a section of the removal 
shape. 
Further, with the machining direction determining means according to the 
invention, if the finish shape contour corresponding to each machining 
step is pond-like, the direction of the machining path is determined to be 
along the contour, if the contour is island-like, the direction is 
determined to be parallel in the longitudinal direction of the contour, 
and if the contour has pond- and island-like portions, the direction is 
determined to be along the island-like portion of the contour. It is thus 
possible to save the labor of determining and inputting the machining 
direction by judging the character or feature of the finish shape as to 
whether the shape is pond- and/or island-like. 
Further, the offset direction determining means according to the invention 
automatically determines the offset direction for the finish shape contour 
corresponding to the work shape after the division such that if the 
contour is pond-like, the offset direction is inwardly of the contour, if 
the contour is island-like, the offset direction is outwardly of the 
contour, and if the contour has pond- and island-like portions, the offset 
direction is inwardly of the contour with respect to the pond-like portion 
and outwardly of the contour with respect to the island-like portion. It 
is thus possible to save the labor of determining and inputting the offset 
direction by judging the character or feature of the finish shape as to 
whether the shape is pond- and/or island-like. 
Further, with the offset amount determining means according to the 
invention, to tool diameter offset the finish shape contour in each 
machining step, if the contour is pond-like, the offset amount is set to 
be the sum of the tool diameter and the finish margin, if the contour is 
island-like, the offset amount is set to be the difference between the 
protruding extent of the tool and the tool diameter, and if the contour 
has pond- and island-like portions, the offset amount is set to the sum of 
the tool diameter and the finish margin for the pond-like portion and the 
difference between the protruding extent of the tool and the tool diameter 
for the island-like portion. It is thus possible to save the labor of 
determining an inputting the offset amount by judging the character or 
feature of the finish shape as to whether the shape is pond- and/or 
island-like. 
Further, the machining condition determining means according to the 
invention determines the machining path pattern such that if the finish 
shape contour in each machining step is pond-like, the pattern is helical, 
if the contour is island-like, the pattern consists of parallel lines, and 
if the contour has pond- and island-like portions, the pattern is one 
obtained by continuously offsetting the island-like portion. It is thus 
possible to save the labor of determining and inputting the machining path 
pattern by judging the character or feature of the finish shape as to 
whether the shape is pond- and/or island-like. 
Further, with the machining condition determining means according to the 
invention the radial and Z direction cut extents are uniformized for each 
machining step. It is thus possible to dispense with the cumbersome 
operation inputting values of uniformized radial and Z direction cut 
extents. 
Further, with the machining condition determining means according to the 
invention machining conditions such as radial and Z direction cut extents, 
radial and Z direction feed speeds, rpm of tool, are called from the 
optimum machining condition data base registered for each tool according 
to the input tool name or tool identification No. and are set for the 
machining step. It is thus possible to simplify the cumbersome operation 
of skillfully determining and inputting the machining conditions such as 
the Z direction cut extent, radial and Z direction feed speeds and rpm of 
the tool from the tool used for the machining. 
Further, with the initial hole determining means according to the invention 
an initial hole machining step is generated if the finish shape contour in 
the machining step is pond-like and is not generated if the contour is 
island-like or has pond- and island-like portions. It is thus possible to 
save the labor of determining and inputting data as to whether the initial 
hole machining step is to be generated by judging the character or feature 
of the finish shape as to whether the shape is pond- and/or island-like. 
Other objects and features of this invention will become understood from 
the following description with reference to the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A first embodiment of the invention may be described. FIG. 1 is a block 
diagram outlining the embodiment of the CAD/CAM system. The illustrated 
CAD/CAM system Comprises a CPU 1, which includes a central processor 11 
for executing operations of controlling the entire system, a drawing 
definition section 12 for defining drawings for removal shape generation, 
a removal shape extraction section 13 for generating removal shapes for 
path generation, a machining step generation section 14 for designating 
coarse and finish machining, tool and machining conditions such as cut 
extents, feed speeds and rpm of the tool according to generated removal 
shape data and optimum machining condition data base, and a path 
generation section 15 for generating paths according to generated 
machining steps. The system also comprises an input unit 2 for inputting 
drawing element data, shape data and other input data and also path 
generation command data and other command data to the CPU 1, a display 
unit 3 for graphically displaying drawing element data, shape data and 
paths based on the results of operations in the CPU 1, a storage unit 4 
for storing operation program data and operation results in the CPU 1, and 
an output unit 5 for outputting the contents displayed on the display unit 
to a printer or the like. 
The term "pond-like" and "island-like" are defined as follows. Namely, a 
form with a top surface finished as shown in FIG. 22A is defined as 
"island-like" form, a form with a bottom face finished as shown in FIG. 
22B is defined as "pond-like" form, and furthermore a form with a top face 
finished as shown in FIG. 22C, in which a portion of the contour is a wall 
as shown in the shadowed section w, is defined as island-like with wall. 
FIG. 2 is a block diagram outlining the drawing definition section 12. The 
section 12 includes a drawing element definition section 121, a curve 
definition section 122, and a shape definition section 123. FIG. 3 is a 
block diagram outlining the removal shape extraction section 13. The 
section 13 comprises a Z direction division section 131 and a contour 
curve inclusion judgment section 132. FIG. 4 is a block diagram outlining 
the machining step generation section 14. The section 14 includes a 
machining step division section 141, a machining step direction 
determination section 142, an offset amount determination section 143, an 
offset direction determination section 144, a machining condition 
determination section 145 and an initial hole determination section 146. 
Now, the operation of the embodiment having the above construction will be 
described in connection with a method of obtaining a finish shape shown in 
FIG. 9A by generating paths shown in FIGS. 10A-10D to 12A-12C with 
reference to the drawing element status view of FIG. 13A, curve status 
view of FIG. 13B, the removal shape Z direction division status view of 
FIG. 14A, removal shape status views of FIGS. 15A-15H to 17A-17H, Z 
direction cut extent uniformization status shown in FIG. 19 and flow 
charts of FIGS. 5 to 8. 
First, commands for defining the two dimensional drawings of the finish 
shape are input (step S1 in FIG. 5) as lines a1 to a7 shown in FIG. 13A, 
X-Y coordinates (i.e., horizontal coordinates) of the end points t1 to t6 
of the lines a1 to a5, X-Y coordinates of the center points of the lines 
a6 and a7 and the radii r1 and r2 of the lines and a7. These are input 
from the input unit 2 to the lines element definition section 12 to cause 
the central processor to generate the lines a1 to a7 and store the 
generated lines a1 to a7 in the storage unit 4 (step S11: drawing 
definition of FIG. 6). 
Then, a command for extracting a curve shown in FIG. 13B from the lines a1 
to a4, a command for extracting a curve C2 from the lines a1 to a4, a 
command for extracting a curve C4 from the line a7 and a command for 
extracting a curve C0 from the lines al to a3 and a5 are input from the 
input unit 2 to the curve definition section 12a to cause the central 
processor 11 to generate the curves C0 to C4 and store the generated 
curves C0 to C4 in the storage unit 4 (step S12: curve definition). 
Further, with respect to the Z direction (i.e., vertical direction) shown 
in FIGS. 14A and 14B, the top and bottom Z heights (vertical coordinates) 
Z3 and Z5 of the curve C1, the top and bottom Z heights Z2 and Z5 of the 
curve C2, the top and bottom Z heights Z1 and Z3 of the curve C3, the top 
and bottom Z heights of Z1 and Z3 of the curve C3, and the top and bottom 
heights Z2 and Z4 of the curve C4 are input together with 
island-like-characteristic data indicating that the finish shape defined 
by the curves C1 to C3 is island-like and pond-like-characteristic data 
indicating that the finish shape defined by the curve C4 is pond-like from 
the input unit 2 to the shape definition section 123 to cause the central 
processor 11 to generate the finish shape V1 shown in FIG. 9A and store 
the generated finish shape V1 in the storage unit 4 (step S13: finish 
shape definition). 
Further, with respect to the Z direction in FIG. 14A, the top and bottom Z 
heights Z0 and Z5 of the curve C0 are input from the input unit 2 to the 
shape definition section 123 to cause the central processor 11 to generate 
the work shape V0 shown in FIG. 9B and store the generated work shape V0 
in the storage unit 4 (step S14: work shape definition). Through the steps 
S11 to S14, drawing definition is completed (step S1: drawing definition 
in FIG. 5). 
Subsequently, a path generation command and a command designating the work 
and finish shapes V0 and V1 shown in FIGS. 9A and 9B as a subject of 
machining are input together with the tool name or tool identification No. 
for each of coarse and finish machining purposes from the input unit 2 and 
restored in the storage Unit 4 (step S2: machining path generation command 
input in FIG. 5). 
According to the above path generation commands stored in the storage unit 
4, the central processor 11 causes the removal shape extraction section 13 
to divide the work shape V0 in the Z direction as shown in FIG. 14B at Z 
direction machining surface heights Z1 to Z4 of the finish shape V1 
between the Z direction top and bottom surface heights Z0 and Z5 shown in 
FIG. 14A and then judge whether the curve C0 shown in FIGS. 13A and 13B 
representing the contour of the work shape V0 and the curves C1 to C4 
shown in the same Figure representing the contour of the finish shape V1 
are included at the Z direction machining surface heights Z1 to Z4. Thus, 
removal shape specification in the radial direction of the tool is made, 
and the specified removal shape data is stored in the storage unit 4 (step 
S3: removal shape extraction in FIG. 5). 
Further, according to the path generation commands noted above, the central 
processor 11 causes the machining step generation section 14 to divide the 
above removal shape stored in the storage unit such as to obtain removal 
shapes V11 to V14 as shown in FIGS. 15A-15H in coarse machining, those V21 
to V24 as shown in FIGS. 16A-16H in bottom finish machining, those V31 to 
V33 as shown in FIGS. 17A-17F in side finish machining and that V1 as 
shown in FIGS. 18A and 18B of the removal shape V24 in initial hole 
formation. FIG. 21 shows machining steps K11 to K14, K22 to K24 and K31 to 
K33 which correspond to the respective removal shapes V11 to V14, V21 to 
V24 and V31 to V33. The central processor 11 causes the section 14 to 
store these machining steps in the storage unit 4. Further, for these 
steps it causes the section 14 to set such machining conditions as 
machining directions d11 to d13 as shown in FIGS. 10A-10D, machining 
directions d21 to d23 and radial cut extents Pr11 to Pr13 and Pr21 to Pr23 
of tool as shown in FIGS. 11A-11D, Z direction cut extents Pz1 to Pz4 of 
tool as shown in FIG. 19, radial and Z direction feed speeds, rpm and 
protruding extent of tool, approach system, escape system, etc. and store 
these set data in the storage unit 4 (step S4: machining step generation 
of FIG. 5). 
Further, according to the above path generation commands the central 
processor 11 causes the path generation section 15 to generate 
progressively paths P11 to P13 as shown in FIGS. 10A-10D for coarse 
machining, initial hole formation path P15, coarse machining path P14, 
bottom finish machining paths P21 to P24 and side finish machining paths 
P31 to P33 as shown in FIGS. 18A and 18B according to the machining steps 
K11 to K14, K21 to K24 and K31 to K33 shown in FIG. 21 and store these 
generated path data in the storage unit 4, thus bringing an end to the 
routine (step S5: path generation). 
It should be noted that, when a path is formed evading the curve C3 like 
path 12 as shown in FIG. 10B, the path is formed so that the path once 
goes around the curve C3 to be evaded from a point t100 where the path 
contacts the curve C3 first, returns to the point t100, and goes further 
continuously along and evading the curve C3, and also so that, when the 
path contacts the curve C3 to be evaded twice or more, the path is formed 
along and evading the curve C3 so that said path will not contact the 
curve C3 anymore in the same turn. 
The operation of the removal shape extraction section 13 embodies a second 
important feature. The Z direction division section 131 in the removal 
shape extraction section 13 rearranges the top and bottom heights Z0 and 
Z5 of the work shape V0 of FIG. 9B in the Z direction shown in FIG. 14A 
and the machining surface heights Z1 to Z4 of the finish shape V1 of FIG. 
9A in the Z direction shown in FIG. 14B, stored in the storage unit 4. The 
rearranging is made in the order of greater heights. Then, the section 131 
omits any machining surface height Z greater than the top height Z0 and 
that less than the bottom height Z5 and generates Z direction removal 
shape data by pairing the machining surface heights Z0 and Z1, Z1 ad Z2, 
Z2 and Z3, Z3 and Z4 and Z4 and Z5, the generated data being stored in the 
storage unit 4 (step S31: Z direction division of FIG. 7). 
The contour curve inclusion judgment section 132 in the removal shape 
extraction section 13 extracts the curves C0 and C3 shown in FIG. 13B, 
found between the top and bottom heights Z0 and Z1, stored in the storage 
unit 4. Then, from the top height Z0, the machining surface height and the 
curves C0 and C3 as a set, it generates a removal shape Vz1 in the radial 
direction as shown in FIG. 14B and stores the generated data in the 
storage unit 4. Likewise, with the machining surface heights Z1 and Z2 and 
the curves C0 and C2 to C4, the machining surface heights Z2 and Z3 and 
the curves C0 to C4, and the machining surface heights Z3 and Z4 and the 
curves C0 to C4 as respective sets, the section 132 generates removal 
shapes Vz2 to Vz4 in the radial direction in FIG. 14B and stores the 
generated data in the storage unit 4, thus bringing an end to the routine 
(step S32: contour curve inclusion judgment for each removal shape of FIG. 
7). 
The operation of the machining step generation section 14 embodies a third 
important feature. The machining step division section 141 in the 
machining step generation section 14 generates a removal shape and a 
machining step from each radial direction removal shape for each of three 
divisional machining steps, i.e., a coarse, a bottom finish and a side 
finish machining step. Specifically, from a radial direction removal shape 
Vz1 the section 141 generates, for the coarse machining step, a removal 
shape V11 with the curves C0 and C3 shown in FIG. 15A as the outer and 
inner peripheral curves of the radial direction margin and with the 
machining surface height Z1 from the top height Z0 plus the finish margin 
Cz1 as the Z direction margin. For this machining step, it also generates 
a machining step K11 shown in FIG. 21. For the finish machining step, it 
generates a removal shape V21 with the curve C3 shown in FIG. 16A as the 
radial direction margin and with a Z direction margin from the machining 
surface height Z1 plus the finish margin Cz1 shown in FIG. 16A to the 
machining surface height Z1, and also generates a machining step K21. For 
the side finish machining step, it generates no machining step because 
there is no side to be machined between the top height Z0 and the 
machining surface height Z1. Likewise, from radial direction removal 
shapes Vz2 to Vz4 shown in FIG. 14B the section 141 generates removal 
shapes V12 to V14 shown in FIGS. 15A-15H, removal shapes V21 to V24 shown 
in FIGS. 16A-16H and removal shapes V31 to V33 shown in FIGS. 17A-17F and 
machining steps K11 to K13, K21 to K23 and K31 to K33 shown in FIG. 21. 
The generated removal shape data and machining step data are stored in the 
storage unit 4. 
With the removal shapes V11 and V12 shown in FIGS. 15A-15D, the outer 
periphery curve is the curve C0 shown in FIG. 13B, representing the 
contour of the work shape. Thus, for the removal shape V11 the machining 
direction is determined to be longitudinal directions d11 in FIG. 10A, and 
for the removal shape V12 it is determined to be longitudinal directions 
d12. With the removal shapes V21 and V22, island-like characteristic data 
is added to the curves C3 and C2 representing the contour of the finish 
shape outer periphery curves. Thus, for the removal shape V21 the 
machining direction is determined to be longitudinal directions d21 shown 
in FIG. 11A, and for the removal shape V22 it is determined to be 
longitudinal directions d22 shown in FIG. 11B. With the removal shapes V13 
and V23, the adjacent outer periphery curves C3 and C4 are of opposite 
shape characters providing pond- and island-like characteristic data, 
respectively. Thus, for these removal shapes the curve C5 as adjacent 
portions of the curves C3 and C4 is extracted, and the machining 
directions are determined to be along the curve C5. (step S41: machining 
direction determination of FIG. 8). 
The offset direction determination section 143 in the machining step 
generation section 14 determines the offset direction with respect to the 
removal shape contour curves. 
The contour curve C0 of the removal shapes V11 and V12, the contour curve 
C3 of the removal shape V21 and the contour curve C2 of the removal shape 
V22 are island-like. Thus, the section 143 determines the offset direction 
with respect to the curves C0, C3 and C3 to be directed outward. 
With respect to the contour curve C4 of the removal shapes V14 and V24, 
which is pond-like, it determines the offset direction to be directed 
inward. With respect to the contour curves C1 and C5 of the removal shapes 
V13 and V23, which have island-like with wall, the section 143 determines 
the offset direction with respect to the pond-like curve C5 to a 
direction, in which there is an intersection point between a curve 
obtained by offsetting the curve C5 and the curve C1, and with respect to 
the island-like curve C1 it determines the offset direction to be a 
direction, in which there is no intersection point between a curve 
obtained by offsetting the curve C1 and the curve C5 (step S42: machining 
condition determination of FIG. 8). 
The machining condition determination section 145 in the machining step 
generation section 14 determines path patterns with respect to the removal 
shape contour curves. 
In FIGS. 15B and 15D, the curve C0 representing the contour of the removal 
shapes V11 and V12, the curve C3 representing the contour of the removal 
shapes V21 and the curve C2 representing the contour of the removal shape 
V22, are island-like. For these contour curves, the section 145 determines 
the path pattern to consist of parallel lines. With respect to the curve 
C4 representing the contour of the removal shapes V14 and V24, which is 
pond-like, the section 145 determines the path pattern to be helical. With 
respect to the curves C1 and C5 representing the contours of the removal 
shapes V13 and V23, which have island-like with Wall, the section 
determines the path pattern to be one which continuously offsets the 
pond-like curve C5 (step S42: machining condition determination in FIG. 
8). 
The operation of the Z direction division section 131 in the removal shape 
extraction section 13 embodies a fourth important feature. In case where 
the finish shape V0a shown in FIG. 20A is a curved shape, the section 131 
causes calculation of a tangent vector to drawing element constituting the 
curve C representing a section of the finish shape V0a. Then, it divides 
the removal shape in the Z height direction at a height Z2a, at which the 
tangent vector is parallel to a horizontal plane. 
The operation of the machining direction determination section 142 in the 
machining step generation section 14 embodies a fifth important feature. 
With the removal shapes V11 and V12 shown in FIGS. 15A-15D, the outer 
periphery curve is the curve CO representing the contour of the work 
shape. Also, the work shape V0 shown in FIG. 9B is island-like. With the 
curve C0, the width in the X direction is greater than the width in the Y 
direction. Thus, the machining direction determination section 142 
determines the machining direction with respect to the removal shape V11 
to be longitudinal directions d11 in the X direction and with respect to 
the removal shape V12 to be longitudinal directions d12 in the X 
direction. With the removal shapes V21 and V22 shown in FIGS. 16A-16D, 
island-like-characteristic data is added to the curves C3 and C2 
representing the outer periphery curve finish shape contours. Thus, like 
the curve C0 the section 142 determines the machining direction to be 
longitudinal directions d12 with respect to the removal shape V21 and 
longitudinal directions d22 with respect to the removal shape V22. With 
the removal shapes V13 in FIGS. 15A-15F and V23 in FIGS. 16E and 16F, 
opposite characters, that is, pond- and island-like characteristic data, 
are added to the adjacent outer periphery curves C3 and C4. Thus, the 
section 142 successively connects coincident drawing elements among those 
constituting the curves C3 and C4 to generate the curve C5 in FIG. 15F as 
adjacent portions of curves. In this way, it determines the machining 
directions d13 and d23 with respect to the removal shapes V13 and V23 to 
be along the curve C5 (step S41: machining direction determination in FIG. 
8). 
The operation of offset direction determination section 143 in the 
machining step generation section 14 embodies a sixth important feature. 
The curve C0 representing the contour of the removal shapes V11 and V12 
shown in FIGS. 15A-15D, represents the contour of the work shape V0. Thus, 
the section 143 judges the curve to be island-like. The curves C3 and C2 
shown in FIGS. 16A-16D, representing the contours of the removal shapes 
V21 and V22, has added island-like characteristic data. Thus, if the 
direction of rotation of the curve C0 is to the right, the section 143 
determines the offset direction for the curve C0 to be leftward direction 
L0 with respect to the direction d00 of tracing the curve C0 in the 
direction of rotation. If the direction of rotation of the curve C0 is to 
the left, on the other hand, the section 143 determines the offset 
direction to be rightward or outward direction R0 with respect to the 
direction d01 of tracing the curve C0 in the direction of rotation. Like 
the curves C0, the curves C3 and C2 are offset outward. 
With the curve C4 representing the contour of the removal shapes V14 in 
FIGS. 15G and 15H and V24 in FIGS. 16G and 16H, the section 143 determines 
the offset direction to be rightward direction R4 with respect to the 
direction d40 tracing the curve C4 in the rotational direction thereof if 
the rotation is to the right and to be leftward or inward direction L4 
with respect to the direction d41 of tracing the curve C4 in the direction 
of rotation if the rotation is to the left. The curve C1 representing the 
contour of the removal shapes V13 in FIG. 15F and V23 in FIG. 16F has 
added pond-like-characteristic data, while the curve C5 has added 
pond-like-characteristic data. Thus, the section 143 determines the offset 
direction for the curve C5 to be directions d5, in which there is an 
intersection point between a curve obtained by offsetting the curve 5 and 
the curve Cl, while determining the offset direction for the island-like 
curve C1 to be outward like the curve C0 (step S42: machining condition 
determination in FIG. 8). 
The operation of the offset amount determination section 144 in the 
machining step generation section 14 embodies a seventh important feature. 
The curve C0 representing the contour of the removal shapes V11 and V12, 
shown in FIGS. 15A-15D, represents the contour of the work shape V0 and is 
judged to be island-like. The curves C3 and C2 representing the contours 
of the removal shapes V21 and V22, shown in FIGS. 16A-16D, have added 
island-like characteristic data. With respect to these curves C0, C3 and 
C2, the section 144 determines the offset amounts as the differences 
between the protrusion extents of the tool and the tool diameter. With 
respect to the curve C4 representing the contour of the removal shapes V14 
in FIGS. 15G and 15H and V24 in FIGS. 16G and 16F has added pond-like 
characteristic data, the section 144 determines the offset amount as the 
sum of the tool diameter and the radial direction finish margin. With the 
curve C1 representing the contour of the removal shapes V13 in FIGS. 15E 
and 15F and V23 in FIGS. 16E and 16F, island-like characteristic data is 
added, while with the curve C5 pond-like characteristic data is added. 
Thus, the section 144 determines the offset amount with respect to the 
curve C5 as the sum of the tool diameter and the finish margin and with 
respect to the curve C1 as the difference between the tool protrusion 
extent and the tool diameter (step S42: machining condition determination 
in FIG. 8). 
The operation of the machining condition determination section 145 in the 
machining step generation section 14 embodies an eighth important feature. 
The curve C0 representing the contour of the removal shapes V11 and V12, 
shown in FIGS. 15A-15D, is of the work shape judged to be island-like, and 
the curves C3 and C2 representing the contours of the removal shapes V21 
and V22 shown in FIGS. 15A-15D and 16A-16D, respectively, have added 
island-like characteristic data. Thus, the section 145 determines the path 
pattern of these curves to consist of parallel lines like the path P22 
shown in FIG. 11B. With the curves C4 representing the contour of the 
removal shapes V14 and V24, which has added pond-like characteristic data, 
the section 145 determines the path pattern to be helical like the path 
P24 in FIG. 11D. The curve C1 representing the contour of the removal 
shapes V13 and V23 shown in FIGS. 15E and 15F and FIGS. 16E and 16F has 
added island-like characteristic data, while the curve C5 has added 
pond-like characteristic data. Thus, the section 145 determines the path 
pattern in this case to be a pattern obtainable by continuously offsetting 
the pond-like curve C5 (step S42: machining condition determination in 
FIG. 8). 
The operation of the machining condition determination section 144 in the 
machining step generation section 14 embodies a ninth important feature. 
First, the section 144 stores the machining steps K11 to K14 for coarse 
machining as shown in FIG. 21 and the Z direction tool cut extents Pz1 to 
Pz4 as shown in FIG. 19 in the storage unit 4. The section 144 then 
uniformizes the tool cut extent Pz4. This is done in such a manner that in 
connection with the removal shape V14 shown in FIGS. 15G and 15H in the 
coarse machining step K14, the top height Z2 plus the finish margin Cz2 
minus the bottom height Z4 minus the finish margin Cz1 is divided by the 
tool cut extent Pz4. Denoting the quotient of the division by D and the 
remainder by L, if L is zero, no particular process is executed. If L is 
not zero, with respect to the removal shape V11 in the coarse machining 
step K11, the top height Z0 minus the bottom height Z1 plug the finish 
margin Cz1 is divided by D+1, and the result of the calculation is 
substituted for the tool cut extent Pz2, thus effecting the 
uniformization. Like the tool cut extent Pz4, the tool cut extents Pz1 to 
Pz3 are also uniformized. 
The machining condition determination section 144 then stores the radial 
direction tool cut extents Pr11 and Pr 12 shown in FIGS. 10A and 10B and 
Pr21 and Pr22 shown in FIGS. 11A and 11B in the machining steps K11, K12, 
K21 and K22 with parallel line machining path pattern in the storage unit 
4. The section 144 then effects uniformization of the radial direction 
tool cut extent Pr11. This is done in a manner that with respect to a 
curve obtained by outwardly offsetting the curve C0 representing the 
removal shape V11 shown in FIGS. 15A-15D by an offset amount corresponding 
to the difference between the tool protruding extent and the tool 
diameter, the width W0 in a direction perpendicular to the machining 
directions d11 shown in FIG. 10A is divided by the radial direction tool 
cut extent Pr11. Denoting the quotient of the division by D2 and the 
remainder by L2, if L2 is zero, no particular process is executed. If L2 
is not zero, with respect to a curve obtained by outwardly offsetting the 
curve C0 by an offset amount corresponding to the difference between the 
tool protruding extent and the tool diameter, the width in the direction 
perpendicular to the machining directions d12 is divided by D2+1, and the 
result of the division is substituted for the radial direction tool cut 
extent Pr11, thus effecting the uniformization. Like the radial direction 
tool cut extent Pr11, the section 144 also uniformizes the radial 
direction tool cut extents Pr12, Pr21 and Pr22. 
The operation of the machining condition determination section 144 in the 
machining step generation section 14 embodies a tenth important feature. 
The CAD/CAM system described previously has an optimum machining condition 
data base registered for each tool. The section 144 calls out machining 
conditions such as radial and Z direction cut extents, radial and Z 
direction feed speeds rom of the tool corresponding to various input tool 
specification data such as shape and number of cutter blades from the 
optimum machining condition data base noted above according to input tool 
name or tool identification NO. and sets the machining steps K11 to K13, 
K1, K14, K21 to K24 and K31 to K33 in the storage unit 4. 
The operation of the initial hole determination section 146 in the 
machining step generation section 14 embodies an eleventh important 
feature. The curve C0 representing the contour of the removal shapes V11 
and V12 shown in FIGS. 15A-15D in the machining steps K11 and K12 shown in 
FIG. 21 represents the contour of the work shape. In this case, the 
section 146 judges the removal shapes V11 and V12 to be island-like and 
generates no initial hole machining step. The curves C3 and C3 
representing the contours of the removal shapes V21 and V22 shown in FIGS. 
16A-16D in the machining steps K21 and K22 shown in FIG. 21 have added 
island-like characteristic data. In this case, the section 146 thus 
generates no initial hole machining step. The curve C4 representing the 
contour of the removal shapes V14 in FIGS. 15A and 15B and V24 in FIGS. 
16G and 16H in the machining steps K14 and K24 shown in FIG. 21 has added 
pond-like characteristic data. In this case, the section 146 generates the 
initial hole machining step K1 before the coarse machining step K14. 
Further, the section 146 starts- the path generation section 15 to obtain 
the X, Y and Z coordinates of the path start position in the coarse 
machining step K14 and then stops the process in the path generation 
section 15 before the path generation. Thus, it obtains the start position 
noted above as the initial hole machining start position. The section 146 
generates the initial hole removal shape I1 with the start position noted 
above and the Z direction top height Z2 plus Cz2 and the bottom height Z4 
plus Cz4 of the removal shape V14 shown in FIGS. 15G and 15H in the coarse 
machining step K14 as data of the removal shape I1. The curve C1 
representing the contour of the removal shapes V13 and V23 in FIGS. 15C 
and 15F and 16E and 16F respectively in the machining step in FIG. 21 has 
added pond-like characteristic data, and the curve C5 shown in FIG. 15F 
has added island-like characteristic data. Thus, the section 146 judges 
the removal shapes V13 and V23 to have island-like with wall and generates 
no initial hole machining step (step S43: initial hole determination in 
FIG. 8). 
Although the invention has been described with respect to a specific 
embodiment for a complete and clear disclosure, the appended claims are 
not to be thus limited but are to be construed as embodying all 
modifications and alternative constructions that may occur to one skilled 
in the art which fairly fall within the basic teaching herein set forth.