Abstract:
In devices for generating a path of a tool of a processing machine by way of computer simulation, an NC program is created using a generated processing path. The NC program used to be corrected by verification of actually moving the processing machine. In contrast, the disclosed processing path generation device has been constituted to be provided with a means for calculating a closest distance and direction from a relationship of a position and posture between a tool and a work at an arbitrary point upon the processing path; a means for imparting a color determined by the closest distance and the direction calculated at the point upon the processing path; a means for panoramically displaying the color imparted to the work; and a means for correcting the relationship of the a position and posture between the tool and the work on the basis of information from a display device.

Description:
CROSS REFERENCE TO PRIOR APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 13/520,188, filed on Jul. 2, 2012, which is a U.S. National Phase application under 35 U.S.C. §371 of International Patent Application No. PCT/JP2011/051629, filed on Jan. 27, 2011 and claims benefit of priority to Japanese Patent Application No. 2010-024360, filed on Feb. 5, 2010. The International Application was published in Japanese on Aug. 11, 2011 as WO 2011/096327 A1 under PCT Article 21(2). The contents of the above applications are hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a technical field for generation of a tool path by checking interference with a device, a tool, a work and the like by means of a computer, which allows a CNC (numerical control apparatus) to execute processing. More specifically, the present invention relates to a technical field of CAM (Computer Aided Manufacturing) for evaluation of interference check upon generation of the tool path. 
     BACKGROUND ART 
     When processing the work, using a device, for an engine and an impeller, which has many narrow portions and curved surfaces, it is necessary to appropriately design a processing path of the tool so as to prevent the device and the tool from interfering with the work. Recently, CAM technique has been employed for designing the processing path by modeling the device, the tool and the work preliminarily in the computer as three-dimensional models using computer simulation technique before processing, and changing a position and posture of the tool model with respect to the computer models of the device and the work along the processing path so as to calculate as needed whether the interference occurs between the models. 
     For example,  FIG. 1  illustrates that an impeller  102  as the work is subjected to cutting work by a 5-axis CNC machining device  101 . In this state, a tool  103  is required to cut the curved surface while getting into a narrow portion of the impeller  102  where blades are overlapped. It is therefore necessary to generate the path of the tool  103  so as to protect the impeller  102  from interference of the portion of the tool  103  other than a blade edge and the device  101 . In this processing path generation, the processing path is generated on the CAM device, and thereafter, an operator checks whether there is the interference on the processing path in reference to computer graphics of the CAM device. If the interference is found, the operator corrects posture and path of the tool based on experience and intuition, and resumes the interference check repeatedly. 
     Following cases will be described as related art. Patent Literature 1 proposes the method for improvement of display with respect to interference on the processing path of the CAM device. Specifically, the part of the tool is classified into the one for processing in contact with the work, for example, a blade edge, and the one not for processing. If the interference with the work occurs at the part of the tool, which is not used for the processing, the display color of the CAM device will be changed to allow easy identification of the interference state. The display color of a trajectory of the tool on the work is made different from that of the work so as to further allow easy identification of the specific point on the processing path where the interference has occurred. 
     Patent Literature 2 proposes the method for high speed interference check in the CAM device. Specifically, the device, tool and work are converted into graphic data, respectively by the CAM device. Unlike the interference check operation performed by image processing for the respective graphic data to determine whether there is an overlap of the processed graphic data, the interference check is performed through logical operation after converting the graphic data into serial signals, thus establishing high speed operation. 
     Non-patent Literature 1 proposes the method for improvement of display of the part of the industrial tool on the processing path where the interference occurs in the CAM device. Specifically, the processable region and the non-processable region are graphically illustrated in configuration space of the tool, which is defined by the tool feed direction and the normal direction at a point in contact with the work. The direction of the tool where the interference with the work occurs in the non-processable region is color displayed so as to ensure easy identification of the interference state. 
     For the color display of the interference direction, when the processing surface of the work is geometrically expanded to the center of the tool, the expanded surface that interrupts the line of sight radially extending from the center of the tool is regarded as the interference. The color imparted to the line of sight is mapped in the tool configuration space as the color representative of the interference state so as to allow determination with respect to direction of the tool in which the interference with the work occurs in the non-processable region based on the color. 
     Non-patent Literature 2 proposes the method of generating the processing path in the CAM device, which avoids the interference in accordance with the operator&#39;s instruction as needed. Specifically, the mechanism is provided to allow the operator to operate a multilinked manipulator added to the CAM device so as to adjust posture and position of the tool in the CAM device. A force sensor is added to the manipulator, which executes a force feedback to limit the work range of the manipulator so that the tool is no longer advanced toward the interfering direction where the tool has interfered with the device and the work in the CAM device, and the operator is notified of the interference state. The color of the region of the work surface in the CAM device, which is processed by the manipulation is changed to a different color to assist generation of the processing path. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: Japanese Patent Application Laid-Open Publication No. 61-203251 
     Patent Literature 2: Japanese Patent Application Laid-Open Publication No. 05-341832 
     Non-Patent Literature 
     Non-patent Literature 1: J. Kaneko and K. Horio, “Fast Generation Method of Tool Posture for 5-Axis Control Machining—Detection of Interference between workpiece surface and cutting tool—”, Proceedings of Saitama University, Engineering Department, No. 39 (2006): p. 93 
     Non-patent Literature 2: Generation of collision-free 5-axis tool paths using a haptic surface Mahadevan Balasubramaniama, Stephen Hoa, Sanjay Sarma, and Yoshitaka Adachi, a Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Mass. 02139, USA, Suzuki Motor Corporation, R&amp;D Center, Yokohama 224-0046, Japan, Computer-Aided Design, Volume 34, Issue 4, 1 Apr. 2002, Pages 267-279 
     SUMMARY OF INVENTION 
     Technical Problem 
     The aforementioned related art allows identification of the interference state of the tool such as the device and the tool with the work. However, there is a problem that it is difficult to easily identify as to how severe the clearance between the tool and the work is and how they are directed on the processing path. Actually, the NC program is made using the generated processing path to actually operate the device, and the clearance is checked as needed before occurrence of the interference. The NC program is corrected while adjusting the posture and path of the tool as needed, resulting in the problem of increase in the number of steps of generating the NC program. 
     For example, Patent Literature 1 discloses that the CAM device allows easy identification of the portion where the interference of the tool with the work occurs by displaying the specific color. However, the clearance before occurrence of the interference cannot be identified as needed. Patent Literature 2 discloses the high-speed interference checking in the CAM device, but does not disclose the method of calculating the clearance before occurrence of the interference. Non-patent Literature 1 describes that the direction in which the clearance becomes severe is color displayed in the configuration space of the tool. However, the clearance of the portion other than the tool, for example, the tool holder, the arm portion of the device and the base of the device cannot be identified as needed. Non-patent Literature 2 allows identification of the interference state of the tool with the work through the force sensing feedback of the manipulator that teaches the interference state of the tool with the work in the CAM device. However, the clearance before occurrence of the interference cannot be identified as needed. 
     That is, the aforementioned related art has the problem of lack of information for correcting the posture and the processing path of the tool before occurrence of the interference although it is possible to check whether the interference on the processing path exists or not on the CAM device. The processing path is corrected based on a result of the interference, and the interference check is performed repeatedly. This may cause the problem of deteriorating manufacturing efficiency. 
     Solution to Problem 
     The present invention for solution of the problem provides a processing path generation device that generates a path of a tool by calculating a positional and attitudinal relationship between a device of an NC processing machine and the tool such as an industrial tool, and a work through simulation executed by a computer, which is provided with closest distance calculation means that calculates a closest distance between the tool and the work at an arbitrary point on the tool path, color/texture imparting means that imparts a different color or a different texture in accordance with a distance and a direction of the work from the tool based on a result of calculation performed by the closest distance calculation means, and display means that displays the color or the texture imparted by the color/texture imparting means on a screen as the color or the texture at a point on the tool path based on the result of calculation performed by the closest distance calculation means. 
     The present invention for solution of the problem provides a processing path generation device that generates a path of a tool by calculating a positional and attitudinal relationship between a device of an NC processing machine and the tool such as an industrial tool, and a work through simulation executed by a computer, which is provided with closest distance calculation means that calculates a closest distance between the tool and the work at an arbitrary point on the tool path, scoring means that awards a score in accordance with a distance and a direction of the work from the tool based on a result of calculation performed by the closest distance calculation means, score totaling means that totals the score determined by the scoring means as a score at a point on the tool path based on the result of calculation performed by the closest distance calculation means to set a score of the path, and display means that displays a list of the total scores of a plurality of patterns each having processing direction of the work and the tool posture changed, which have been obtained through the closest distance calculation means, the scoring means and the score totaling means. 
     The present invention for solution of the problem provides a processing path generation method that generates a path of a tool by calculating a positional and attitudinal relationship between a device of an NC processing machine and the tool such as an industrial tool, and a work through simulation executed by a computer, which calculates a closest distance between the tool and the work at an arbitrary point on the tool path, imparts a different color or a different texture in accordance with a distance and a direction of the work from the tool based on a result of the calculation, and displays the imparted color or the imparted texture on a screen as the color or the texture at a point on the tool path based on the result of the calculation. 
     The present invention for solution of the problem provides a processing path generation method that generates a path of a tool by calculating a positional and attitudinal relationship between a device of an NC processing machine and the tool such as an industrial tool, and a work through simulation executed by a computer, which calculates a closest distance between the tool and the work at an arbitrary point on the tool path, awards a score in accordance with a distance and a direction of the work from the tool based on a result of the calculation, totals the awarded score based on the calculation result as a score at a point on the tool path to set a score of the path, executes processes of calculating the closest distance, awarding the score, and totaling the score to set the score of the path for a plurality of patterns each having processing direction of the work and the tool posture changed, and displays a list of the total scores of the plurality of patterns each having processing direction of the work and the tool posture changed, which have been obtained through execution of the processes. 
     Advantageous Effects of Invention 
     The present invention allows panoramic identification of the clearance between the tool or processing machine and the part over the whole processing region, and design of the processing path while preliminarily adjusting the posture and path of the tool in reference to the direction of the severe clearance as needed on the CAM device. This makes it possible to generate the appropriate processing path for a short period of time without performing the generally employed operation by repeating correction of the processing path based on a result of the interference and interference checking, thus contributing to manufacturing efficiency. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of an impeller (work) and an industrial tool (tool) for cutting of the impeller using a 5-axis CNC machining device. 
         FIG. 2A  is a block diagram of a structure formed by combining a CAD device, a CAM device, an NC program generation device and an NC processing machine. 
         FIG. 2B  is a block diagram showing a structure of processing means of the CAM device. 
         FIG. 3  is a flowchart representing process steps of generating the tool path according to an embodiment. 
         FIG. 4  is a sectional view illustrating a relationship between parts of the tool and the work. 
         FIG. 5  is a view showing a result of conversion of information on the closest distance and direction into colors. 
         FIG. 6  is a view showing a result of arranging colors calculated with respect to points on the tool path. 
         FIG. 7  is a view for setting a posture of the tool by two angles (α, β) in three-dimensional coordinate system while setting a contact point between the tool and the work to an original point. 
         FIG. 8  is a sectional view showing a relationship between the tool and the work during processing when the posture to the processing surface is set by two angles (α, β). 
         FIG. 9  is a view showing the posture of the tool set by two angles (γ, δ) in the fixed three-dimensional coordinate system. 
         FIG. 10  is a sectional view showing a relationship between the tool and the work during processing when setting the posture to the processing surface by two angles (γ, δ). 
         FIG. 11  is a score map that replaces the color pattern. 
         FIG. 12  shows a result of scoring the respective points on the tool path using the score pattern. 
         FIG. 13  is a front view of the screen showing calculated scores of a plurality of patterns of processing directions of the work and the tool postures which have been changed for the respective processing path groups in the form of a table. 
         FIG. 14  is a front view of the screen of an output display, which includes a general panoramic view illustrating the positional and attitudinal relationship between the tool and the work, a processing path number display portion, an interference check target display portion, a tool posture display portion and a clearance map display portion. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     An embodiment of the present invention will be described referring to the drawings. 
       FIG. 2A  schematically shows a structure of the NC processing system to which the present invention has been applied. 
     The NC processing system includes a CAD device  210 , a CAM device  220 , an NC program generation device  230 , and an NC processing machine  240 . 
     The CAD device  210 , the CAM device  220  and the NC program generation device  230  are provided with processing means  211 ,  221  and  231 , display means  212 ,  222  and  232 , input means  213 ,  223  and  233 , direct access storage means  214 ,  224  and  234 , and indirect access storage means  215 ,  225  and  235 , respectively. 
     The processing means  211 ,  221  and  231  serves to perform the mathematical operation such as a central processing unit or CPU. The direct access storage means  214 ,  224  and  234  as the means that allows memory access at the speed equivalent to an internal processing speed of the processing means  211 ,  221  and  231  may be formed as a cache memory for the processing means  211 ,  221  and  231 , or memory means such as a DRAM. The indirect access storage means  215 ,  225  and  235  as the means that allows memory access at the speed different from the internal processing speed of the processing means  211 ,  221  and  231  may be formed as such medium as a hard disk, an optical disk and a magnetic tape, or the hard disk, the optical disk, the magnetic tape and the DRAM in the other computer via internet/intranet. The display means  212 ,  222  and  232  denotes visual display means such as means for display and printing. The input means  213 ,  223  and  233  denotes the means for inputting all the information except the one from the direct access storage means  214 ,  224  and  234 , and the indirect access storage means  215 ,  225  and  235  to the processing means  211 ,  221  and  231 , for example, a keyboard, a mouse, a digitizer, and a sensor. 
     The display means  212 ,  222  and  232 , and the input means  213 ,  223  and  233  may be shared by the CAD device  210 , the CAM device  220  and the NC program generation device  230 . 
     The CAD device  210  allows the processing means  211  to generate calculation models that represent three-dimensional configurations of the tool and the work used by the NC processing machine  240 , and the calculation model that represents the three-dimensional configuration of the NC processing machine  240  by itself. 
     The CAM device  220  obtains the calculation models generated by the CAD device  210 , which represent the three-dimensional configurations of the NC processing machine, the tool and the work, and generates the processing path of the tool for processing the work with the NC processing machine  240  based on the positional and attitudinal relationship among those calculation models. That is, the processing means  221  calculates the path of the tool that moves relative to the work based on the positional and attitudinal relationship among those calculation models when processing the work set in the NC processing machine using the tool. The interference check is conducted whether the portion of the tool other than the processing portion interferes with the work set in the NC processing machine, or the NC processing machine interferes with the work by calculating the interference state of the calculation model based on the positional and attitudinal relationship among the calculation models at an arbitrary point on the path. 
     Especially, the indirect access storage means  225  of the CAM device  220  includes, in order to perform the present invention, a data storage region  226  that stores data of the closest distance between the tool and the work, and the direction, and a data table  227  for determination of the display color based on the distance and direction. The data storage region  226  and the data table  227  are copied to the direct access storage means  224  as needed for usage and correction, and further stored in the indirect access storage means  225  as needed. 
     Referring to  FIG. 2B , the processing means  221  of the CAM device  220  includes a processing path data generation unit  2211 , a closest distance/direction calculation unit  2212 , a closest distance/direction color setting unit  2213 , and a tool/work relationship correction unit  2214 . 
     The NC program generation device  230  generates the NC program so that the NC processing machine  240  performs the processing with the tool for the target work, which is imparted with a control command unique to the NC processing machine  240  using the processing path information generated by the CAM device  220 . 
     An example of the processing system with the above-described structure will be described in detail hereinafter. 
       FIG. 3  represents process steps executed by the CAM device  220  and the NC program generation device  230  when applying the embodiment to the system structure shown in  FIG. 2A . This embodiment relates to a method and a device for generation of the NC program of the NC processing machine  240  by the NC program generation device  230  based on the process for sophistication of the function of the CAM device  220  as shown in  FIG. 2A  and results thereof. Specifically, processing performed by the structure shown in  FIG. 1  through the process steps executed in the CAM device  220  will be described. 
     The CAM device  220  obtains calculation models that represent three-dimensional configurations of a portion  101  of the NC processing machine  240  around the part for holding the tool and the work, a tool  103 , and a work  102  which have been preliminarily generated by the CAD device  210 , and stores those models in the indirect access storage means  225  (S 301 ). Then the calculation model is copied to the direct access storage means  224 , and the processing path data generation unit  2211  generates the processing path of the tool  103  that processes the work  102  with the NC processing machine  240  based on the positional and attitudinal relationship among the calculation models of the NC processing machine, the tool and the work. The resultant data are stored in the indirect access storage means  225  (S 302 ). 
     The processing path data stored in the indirect access storage means  225  are directly copied to the direct access storage means  224  so that at least one arbitrary point on the processing path is set for calculation of the interference state to check whether the portion of the tool  103  other than the processing part interferes with the work  102  set in the NC processing machine  240 , and the portion  101  of the NC processing machine  240  around the part for holding the tool and the work interferes with the work  102  (S 303 ). At least one calculation model of the work, and at least one calculation model of the tool such as the industrial tool and the NC processing machine for the interference calculation are selected (S 304 ). 
     The point on the processing path for the interference calculation is selected (S 305 ). If there is no point to be selected, it is determined that all the processing has been finished (S 306 ). The position and posture of the work and the tool at the point is calculated (S 307 ). Then one of the plurality of works is selected (S 308 ). If there is no work to be selected, the process proceeds to step S 313  (S 309 ). If the work to be selected exists, the process proceeds to the next step where one tool is selected from a plurality of tools (S 310 ). If there is no tool to be selected, the process returns to step  308  (S 311 ). 
     Then the closest distance/direction calculation unit  2212  obtains the closest contact point between the selected work and the tool, and the distance therebetween and the direction from a tool reference point. The data of the distance and the direction are stored in the data storage region  226  with respect to the closest distance and the direction between the tool and the work as shown in  FIG. 2A  (S 312 ). 
     The process steps from  308  to  312  are repeatedly executed with respect to combinations of all the works and all the tools in accordance with the positional and attitudinal relationship therebetween at the point on the processing path selected in step  305 . Then the combination of the tool and the work at the closest distance is selected from those stored in the data storage region  226  with respect to the closest distance between the tool and the work, and the direction as shown in  FIG. 3  (S 313 ). 
     The closest distance/direction color setting unit  2213  determines the color in accordance with the distance and direction of the extracted combined tool and the work at the closest distance in reference to the data table  227  for determining the display color in accordance with the distance and direction (S 314 ). The color is displayed on the display means  222  as the one at the point on the processing path (S 315 ). 
     Thereafter, the process returns to S 305  where the same process is executed until no point is left to be selected, that is, the process ends at all the points on the processing path in S 306 . This makes it possible to identify the closest distance and direction between the work  102  and the tool  103 , and the direction at all the points on the processing path as colors on the processing path. In other words, the display means  222  of the CAM device  220  allows easy identification of the clearance between the work and the tool over the entire processing region in a panoramic manner based on change of the color. 
     The tool/work relationship correction unit  2214  executes processing using the information displayed on the display means  222  based on the data input from the input means  223  (for example, the data displayed on the display means  222  are corrected and input by the input means  223  of interactive type). The result is displayed on the display means  222  again so as to allow appropriate design of the processing path while adjusting the posture and the passage of the tool  103  as needed (S 316 ). Upon completion of adjustment of the posture and path of the tool  103 , those data are transmitted to the NC program generation device  230 . The processing means  231  allows the NC processing machine  240  to generate the NC program for processing the work  102  (S 317 ). Upon completion of NC program generation, a series of operations ends. 
       FIG. 4  schematically shows a relationship between a part  401  of the tool  103  and a part  406  of the work  102  ( 403 ) in the process steps S 313  and S 314  as described referring to  FIG. 3 . The part  401  of the tool  103  is in contact with the work  403  at a contact point  402  between the tool  103  and the work  102  ( 403 ). Supposing that the advancing direction of the part  401  of the tool  103  is set to an X-direction  404  at the contact point  402 , and the normal direction of the work at the contact point  402  is set to a Z-direction  405 , the three-dimensional coordinate system having the contact point  402  as the original point may be defined. When the part  401  of the tool  103  is operated to process the work along the processing path, it needs to execute the processing while avoiding the interference with the other part  406  of the work  403 . The closest distance between the part  401  of the tool  103  and the part  406  of the work  403 , and the direction  407  have to be constantly identified, and the processing path has to be adjusted as needed in accordance with the identified state. 
     The structure according to the embodiment intended to solve the aforementioned problem converts the information on the closest distance and the direction  407  into color. The color is displayed on the display means  222  of the CAM device  220  as the color corresponding to the contact point  402 . This allows an operator to identify the interference state as needed, and further identify the processing path as needed based on the state. 
       FIG. 5  graphically shows the process for converting the information on the closest distance and the direction  407  shown in  FIG. 4 , which is executed in steps S 313  and S 314  of the process shown in  FIG. 3 . An x-axis  501  corresponds to the x-axis  404  shown in  FIG. 4 , and a z-axis  502  in the vertical direction with respect to the drawing corresponds to the z-axis  405  shown in  FIG. 4 . The view of  FIG. 5  seen from the plane A-A′ corresponds to the view shown in  FIG. 4 . In the three-dimensional coordinate system defined by the x-axis  501  and the z-axis  502 , a pattern  503  to which a color is arranged in accordance with the distance and direction from the original point in an xy-plane that contains the x-axis  501  is set and stored in the data table  227  for determining the display color in accordance with the distance and direction of the indirect access storage means  225  of the CAM device  220 . A line  504  formed by projecting the closest distance and the direction  407  shown in  FIG. 4  to the xy-plane is drawn in reference to the data table  227 . A color  505  pointed by the tip of the line is set as the color of the original point of the coordinate system. 
     The color pattern  503  may have its color or brightness changed, or different textures arranged. The color pattern  503  does not have to be arranged on the contact point  402  shown in  FIG. 4 , but may be evaluated at an arbitrary part of the tool. The closest distance and the direction  407  are projected to draw the line  504  in accordance with the position and posture of the arranged color pattern  503  so as to determine the representative color. 
       FIG. 6  shows a result of the respective points on the tool path to which colors are imparted through the interference check of the processing path using the method as described referring to  FIGS. 4 and 5 . A plurality of arrow marks  601  represent rows of the generated processing paths. If an obstacle  602  exists on the tool path, an algorithm according to the present invention as described referring to  FIGS. 3, 4 and 5  is executed at the representative points  603  on the tool paths illustrated as white circles. Mapping is conducted on the processing surface by imparting the selected colors to hexagons  604  with the corresponding representative points each as the center. As the color is selected through calculation of the closest distance between the tool and the obstacle  602  with respect to the representative point  603  on each of the tool paths, the color imparted to the representative point  605  close to the obstacle  602  is different from the color imparted to the representative point  606  far from the obstacle. The panoramic view of the processing surface provides a macroscopic color pattern. 
       FIG. 6  illustrates a pattern that includes the closest region as a group to which the color of the representative point  605  is imparted, a region as a group to which the color of the representative point  604  is imparted, a region as a group to which the color of the representative point  607  is imparted, and a region as a group to which the color of the representative point  606  is imparted. This pattern easily allows visual identification of the clearance between the tool and the work as to which part on the processing surface, which direction with respect to the tool, and what extent. Based on the information, the posture of the tool and the processing path are adjusted as needed to allow generation of the processing path that establishes short processing period for a short period of time. 
       FIG. 7  is an explanatory view representing the three-dimensional coordinate system with the contact point  402  as the original point and the posture of the tool  703  ( 103 ) when the advancing direction of the part  401  of the tool  103  at the contact point  402  shown in  FIG. 4  is set to the x-direction  404  and the normal direction of the work  403  at the contact point  402  is set to the Z-direction  405 . An x-axis  701  of the three-dimensional system shown in  FIG. 7  corresponds to the X  404  shown in  FIG. 4 , and a z-axis  702  corresponds to the Z  405  shown in  FIG. 4 . 
     A relationship between a representative line  704  indicating the posture of the tool  703  and the coordinate system may be represented by an angle α  706  defined by an auxiliary line  705  formed by projecting the representative line  704  to an xy-plane of the coordinate system and the x-axis  701 , and an angle β  707  defined by the representative line  704  and the Z-axis  702  in the plane formed by the z-axis  702  and the auxiliary line  705 . For example, the posture of the tool with respect to the processing surface has to be preliminarily determined for generation of the rows  601  of the processing path shown in  FIG. 6 . The posture of the tool may be determined by setting the angles (α, β) as shown in  FIG. 7 . 
       FIG. 8  shows the state of the tool  103  during the processing when setting the posture to the processing surface by two angles (α, β) shown in  FIG. 7 . Referring to  FIG. 7 , the angles (α, β) are determined in the three-dimensional system defined on the processing surface. The posture of the tool  103  shown in  FIG. 8  changes as  804 ,  805  and  806  in  FIG. 8  show accompanied with movement of the contact point as  801 ,  802  and  803  show for the purpose of keeping a constant posture with respect to the normal line of the respective contact points for the processing. From a view fixed to the drawing, the tool  103  seems to swing. The posture  804  of the tool  103  at a contact point  801  is directed away from an obstacle  807  in the clearance between the obstacle  807  and the tool  103  on the tool path. Meanwhile, the posture  806  of the tool  103  at the contact point  803  is sharply brought to be close to the obstacle  807 , which increasingly causes the risk of collision between the tool  103  and the work  102 . This embodiment easily allows visual identification of the aforementioned state as to which part of the work  102  on the processing surface, which direction with respect to the tool  103 , and what extent so as to adjust the posture of the tool as needed. 
       FIG. 9  is an explanatory view of a method different from the tool posture determination method as described referring to  FIG. 7 . The three-dimensional system has the contact point  402  shown in  FIG. 4  as the original point corresponding to an original point  901  shown in  FIG. 9 , the x-axis  404  shown in  FIG. 4  corresponding to an x-axis  902 , and the z-axis  405  shown in  FIG. 4  corresponding to a z-axis  903 . Referring to  FIG. 9 , unlike the xyz coordinate system, a fixed coordinate which does not influence the posture of the tool  904  with respect to the work  102  is defined for the purpose of defining the posture of the tool  904 . In other words, the posture of the tool  904  is defined in the fixed coordinate with a point  906  as the original point on a representative line  905  indicating the posture of the tool  904 . The representative line  905  may be expressed by an angle γ  909  defined by an auxiliary line  907  formed by projecting the representative line  905  to an x 0 y 0  plane in the fixed coordinate system and an x 0 -axis  908 , and an angle δ  911  defined by the representative line  905  and a z 0 -axis  910  in a plane formed by the z 0 -axis  910  and the auxiliary line  907 . For example, the posture may be determined by the angles (γ, δ) shown in  FIG. 9  for generation of the rows  601  on the processing paths shown in  FIG. 6 . 
       FIG. 10  shows the state of the tool  103  during the processing when setting the posture to the processing surface by two angles (γ, δ) as described referring to FIG.  9 . The angles (γ, δ) are determined in the fixed coordinate system A 01  as shown in  FIG. 9 . Referring to  FIG. 10 , the tool  103  has its posture changed as shown by A 05 , A 06  and A 07  accompanied with movement of the contact point with the work  102  as shown by A 02 , A 03  and A 04  for the purpose of processing at a constant posture with respect to the fixed coordinate system A 01 . From the view fixed to the drawing, the tool seems to always keep the posture constant. In order to perform the processing by keeping the posture, the rake angle of the blade edge has to be kept constant by correcting the contact point between the blade edge of the tool and the work as needed. However, this may provide the advantage that the clearance between an obstacle A 08  and the tool  103  on the tool path does not sharply bring the tool to be close to the work when the contact point moves from A 02  to A 04  as shown in  FIG. 8 . The aforementioned state is displayed on the display means  222  in different colors to easily allow visual identification of the state as to which part of the processing surface, which direction with respect to the tool  103  and what extent. This makes it possible to adjust the posture of the tool as needed. 
       FIG. 11  is a view formed by replacing the color pattern  503  shown in  FIG. 5  with scores. An x-axis B 01  corresponds to the x-axis  404  shown in  FIG. 4 , and a z-axis B 02  vertically directed with respect to the drawing corresponds to the z-axis  405  shown in  FIG. 4 . In the three-dimensional coordinate system defined by the x-axis B 01  and the z-axis B 02 , a pattern B 03  of the score obtained by the distance and direction from the original point in the xy-plane that contains the x-axis B 01  is set. Referring to  FIG. 11 , the score becomes higher as it is closer to the original point of the coordinate system. The score pattern B 03  is expressed by positive integer in  FIG. 11 . However, the pattern may be expressed by negative integer or real number. Referring to  FIG. 11 , the pattern is set so that the same scores are concentrically arranged with respect to the original point of the coordinate system. The coordinate system defined by the tool feeding direction and the normal line of the processing surface is directed from front to back and from side to side, and accordingly, positive and negative scores may be arranged at the right and left sides, respectively, or scores may be weighted with respect to the direction. 
       FIG. 12  shows results of scoring the respective points on the tool path using the score pattern shown in  FIG. 11 . A plurality of arrow marks C 01  represent rows of the generated processing paths. In the state where an obstacle C 02  exists on the tool path, representative points C 03  on the tool paths are scored using the score pattern B 03  described referring to  FIG. 11 . As the closest distance between the tool and the obstacle C 02  is calculated in reference to the representative point C 03  on the tool path, the score at a representative point C 04  close to the obstacle C 02  is different from the one at a representative point C 05  distant from the obstacle C 02 . The sum of the scores obtained for all the C 06  on the processing path allows comparison among scores of the generated processing path groups from the viewpoint of the clearance between the tool  103  and the work  102 . 
       FIG. 13  shows an example of a screen  1300  representing comparison among score results of the generated processing path groups from the viewpoint of clearance between the tool and the work as described referring to  FIG. 12 . Referring to  FIGS. 11 and 12 , the score is lowered as the clearance becomes larger. As the sum of values for all the processing paths becomes smaller, the score is considered as higher. Several patterns of combination of the work processing direction and the tool posture are prepared so that the respective scores of the processing path groups are calculated according to the present invention and listed as shown in  FIG. 13 . 
     Referring to  FIG. 13 , the tool path pattern classified by the work processing direction and the processing pitch is defined as a tool path No. and displayed on a display section  1301 . Several patterns of the tool posture combination are defined as tool path design Nos., and respective scores are obtained and displayed on a display section  1302 . Referring to  FIG. 13 , the strategy with respect to how well the spatial processing surface is processed by the tool for the respective patterns may be compared among those based on scalar quantity, that is, score. When clicking a switch screen button  1303 , the next screen shown in  FIG. 14  is displayed. 
       FIG. 14  shows an example of a screen  1400  displayed upon execution of the present invention on the CAM device. Referring to the exemplary screen, a positional and attitudinal relationship between the tool and the work is shown as a whole panoramic view  1401 . A tool path No.  1402  and an interference check target  1403  are input. The tool posture is determined by two angles (α, β) using the coordinate system fixed to the processing surface as shown in  FIGS. 7 and 8 , and displayed on a tool posture display section  1404 . Based on the input information, the clearance between the tool and the work along the processing path is calculated through the method according to the present invention, and the result is displayed as a clearance map  1405 . This screen easily allows visual identification of the clearance between the tool and the work as to which direction with respect to the tool, and what extent during the processing with the tool posture determined to the tool path. This makes it possible to adjust the tool posture as needed. 
     Upon designating a new path No. on the path No. designation column  1402 , the whole panoramic view display section  1401  and the clearance map display section  1405  are switched in accordance with the designated path No. for display. When changing the interference check target on the interference check target designation section  1403 , the whole panoramic view display section  1401  and the clearance map display section  1405  are also switched in accordance with the designated interference check target. 
     The clearance map display section  1405  shown in  FIG. 14  corresponds to the embodiment shown in  FIG. 6 . However, it may be displayed using numerical values as described referring to  FIG. 12 . 
     When clicking the switch screen button  1303 , the screen shown in  FIG. 13  is displayed. 
     INDUSTRIAL AVAILABILITY 
     The present invention is applied to technical field of CAM (Computer Aided Manufacturing) for interference check evaluation of the device, the tool and the work upon generation of a tool path for the purpose of performing processing using the CNC (numerical controller). 
     REFERENCE SIGNS LIST 
     
         
           101  . . . 5-axis CNC machining device 
           102  . . . Impeller 
           103  . . . Tool 
           210  . . . CAD device 
           211  . . . Processing device 
           212  . . . Display device 
           213  . . . Input device 
           214  . . . Direct access storage device 
           215  . . . Indirect access storage device 
           220  . . . CAM device 
           221  . . . Processing device 
           222  . . . Display device 
           223  . . . Input device 
           224  . . . Direct access storage device 
           225  . . . Indirect access storage device 
           227  . . . Data table for determination of display color by distance and direction 
           230  . . . NC program generation device 
           231  . . . Processing device 
           232  . . . Display device 
           233  . . . Input device 
           234  . . . Direct access storage device 
           235  . . . Indirect access storage device 
           240  . . . NC processing machine 
           401  . . . Part of tool 
           403  . . . Work 
           601  . . . Row of generated processing path 
           602  . . . Obstacle on tool path 
           603  . . . Representative point on tool path 
           604  . . . Hexagon with representative point as center 
           703 ,  904  . . . Tool 
           1300 ,  1400  . . . Display screen 
         A 08  . . . Obstacle on tool path 
         C 01  . . . Row of generated processing path 
         C 02  . . . Obstacle on tool path 
         C 06  . . . Whole processing path