JP5610883B2 - Processing simulation apparatus and method - Google Patents

Description

  The present invention relates to machining simulation, and more particularly to a cutting simulation apparatus and method for simulating a change in the shape of a workpiece by cutting using an NC machine tool.

  In machining using an NC (Numerical Control) machining program (hereinafter, machining program) created by a CAM (Computer Aided Manufacturing) system or the like, there may be a machining defect resulting in a finished result different from the intention of the machining designer.

  In the case of cutting, many of the machining defects are caused by “uncut residue” where the part of the workpiece that should be originally cut remains without being cut, or by “cutting” where the workpiece is cut beyond the target finished surface. These appear mainly because of problems in the machining program itself.

  In order to avoid such machining defects, the CAM system used to prepare the machining program is usually equipped with a machining simulation function, and this machining defect should be avoided by verifying the machining program in advance. Can do.

  In addition to machining defects that occur due to obvious problems on the machining program, such as uncut or overcut, there are machining defects that leave striped or scratched work scratches on the surface of the workpiece. .

  In particular, when machining a highly designed part that uses a large number of curved surfaces, such as mold processing, it is important that the finished surface is smooth, and the occurrence of processing flaws often becomes a problem.

  The cause of such machining flaws is that the machine tool does not follow the instructions of the machining program because the setting of machining conditions, machine tool mechanical accuracy, and control parameter adjustment are not appropriate, There are various cases such as the case where a minute error appears due to the identification of the machining condition or the machine error of the machine tool, and it is generally difficult and time consuming to identify the cause and take countermeasures. .

  Patent Documents 1 to 3 disclose a method for supporting the work of identifying the cause of occurrence of a processing flaw. All of these display data, such as data determined according to the characteristic amount of the tool movement trajectory, marker graphic, or radial line graphic, and display the tool movement trajectory data in combination with these display attributes. From the features of the pattern, the location where machining flaws are likely to occur is identified, and the cause of machining flaws is identified by comparing and comparing with machining flaws caused by actual machining results.

Japanese Patent No. 3834268 Japanese Patent No. 3878516 Japanese Patent No. 3920144

  In the above technology that combines display attributes with the tool movement trajectory, there is no simple correspondence between the display pattern of the tool movement trajectory combined with the display attributes and the appearance of machining flaws. Cannot be clearly separated.

  In general, the tool movement trajectory passes through a position separated from the machining surface by the tool radius. Conversely, the machining surface is created at a position separated from the tool movement locus by the tool radius. At this time, the relative positional relationship between the machining surface and the tool changes in each part of the tool movement (especially in the case of curved surface machining), so the display pattern of the tool movement locus trace is not always fine. It cannot be said that it represents a shape pattern.

  As a result, the comparison and collation between the display pattern of the tool movement trajectory and the observation result of the machining flaw generated when the machining is actually performed becomes qualitative, and there is a possibility that the cause of occurrence cannot be clearly identified.

  Further, in the above-mentioned patent document, colors and auxiliary figures as display attributes correspond to various characteristic quantities such as the inclination of the tool movement trajectory and the amount of change thereof, the amount of displacement from the reference position, the radius of curvature, etc. As described above, since there is no simple correspondence between the display pattern of the tool movement trajectory and the fine shape pattern of the machining surface (including machining flaws), the cause of occurrence such as the width, length, depth, and direction of the machining flaw It is difficult to quantitatively analyze the process and to formulate countermeasures for eliminating processing flaws.

  The present invention has been made in view of the above, and in cutting simulation, machining that can more intuitively grasp various characteristic amounts that support quantitative analysis regarding the occurrence state and occurrence mechanism of a processing flaw. An object is to obtain a simulation apparatus and method.

  In order to solve the above-described problems and achieve the object, the present invention simulates cutting based on tool data indicating the type and shape of a tool and tool movement trajectory data indicating a tool movement trajectory. A means for generating shape data indicating the shape of an object, and a characteristic amount related to creation of a point of interest for a point of interest on a processed surface of a workpiece in a cutting process, shape data, tool data, and tool movement trajectory Means for calculating based on the data, and means for superimposing and displaying the characteristic amount on the projection image of the workpiece along the predetermined line-of-sight direction generated based on the shape data. And

  According to the present invention, since the characteristic amount related to the tool movement related to the creation of the machined surface of the workpiece can be displayed superimposed on the workpiece shape, the causal relationship between the tool movement and the creation of the machined surface can be visually determined. As a result, it becomes possible to grasp, and it is easy to estimate the cause of the occurrence of a machining defect and to plan a countermeasure for avoiding the outside of the machining defect from the display contents and the superimposed characteristic amount pattern.

FIG. 1 is a diagram showing a configuration of a machining simulation apparatus according to the first embodiment. FIG. 2 is a diagram illustrating a state in which a machining surface including a point of interest is created by the movement of the tool along the movement trajectory segment forming the tool movement trajectory data. FIG. 3 is a diagram for explaining the operation of calculating the direction of the target point viewed from the tool reference point as the tool movement characteristic amount. FIG. 4 is a diagram illustrating a configuration of a machining simulation apparatus according to the second embodiment. FIG. 5 is a diagram illustrating an example of an operation in the tool movement characteristic amount difference calculation unit when the position of the tool reference point is a characteristic amount.

  Embodiments of a machining simulation apparatus and method according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration of a machining simulation apparatus according to Embodiment 1 of the present invention. The machining simulation apparatus core 1 includes a cutting shape processing unit 2, a cutting shape display unit 3, a tool movement characteristic amount calculation unit 4, and a simulation data storage unit 5.

  The simulation data storage unit 5 stores each data of tool data 6, tool movement trajectory data 7, and workpiece shape data 8.

  In addition to these, the machining simulation apparatus as a whole includes a display device 9 that is a display output destination of the workpiece shape, and an input device 10 for a user to perform an operation operation of the simulation apparatus and to instruct a visual line direction of display. Has a keyboard and mouse.

  In the tool data 6, information on a tool type such as a ball end mill and a tool shape such as a tool diameter and a tool length is described with respect to a tool used for a cutting process to be simulated.

  The tool movement trajectory data 7 describes information related to the movement trajectory of the tool reference point in the cutting process to be simulated. As the tool reference point, for example, in a ball end mill tool used for die machining or the like, a hemispherical center point of the tool tip is used. In general, the tool movement trajectory data 7 is expressed by a series of divided movement trajectory segments, and each movement trajectory segment indicates the position of the tool movement start point and end point and the movement mode from the start point to the end point (tool movement). Information on how to move (indicates linear, arc, etc.).

  The workpiece shape data 8 is three-dimensional shape data representing the momentary shape from the start to the end of the simulation of the workpiece to be cut.

  The cutting shape processing unit 2 receives the tool data 6 and the tool movement trajectory data 7 stored in the simulation data storage unit 5 and inputs the tool described in the tool data 6 by the tool movement trajectory data 7. Cutting is simulated by moving along the trajectory and cutting and deforming the workpiece shape data 8 stored in the simulation data storage unit 5.

  The cutting shape display unit 3 and the tool movement characteristic amount calculation unit 4 operate in cooperation with each other. As a basic process, the cutting shape display unit 3 receives the workpiece shape data 8 stored in the simulation data storage unit 5 and inputs a projection image of the workpiece shape along a specified line-of-sight direction to the display device 9. Output. In this process, the cutting shape display unit 3 displays the characteristic amount to be displayed superimposed on the pixel point data on the projection image corresponding to each point on each processing surface of the workpiece shape data 8, as tool movement characteristics. An inquiry is made to the amount calculation unit 4.

  In response to the inquiry from the cutting shape display unit 3, the tool movement characteristic amount calculation unit 4 uses a designated point on the designated machining surface of the workpiece as a point of interest, and the workpiece shape in the simulation data storage unit 5. With reference to the data 8, the tool data 6, and the tool movement trajectory data 7, the characteristic amount related to the tool movement involved in the creation of the point of interest is calculated from the tool movement trajectory data 7 and output to the cutting shape display unit 3.

  The cutting shape display unit 3 superimposes and displays the characteristic amount calculated by the tool movement characteristic amount calculation unit 4 on the pixel point being processed. In the present embodiment, for superimposing the characteristic amount on the pixel point, a method is used in which a color determined based on the magnitude of the characteristic amount and the sign of the sign is used as the pixel value of the pixel point. Since the characteristic amount is superimposed and displayed with color information, it is easy to visually grasp the feature amount pattern.

  In the present embodiment, as the characteristic amount calculated by the tool movement characteristic amount calculation unit 4, three of the tool reference point position, the tool moving direction, and the direction of the point of interest viewed from the tool reference point are used.

  Hereinafter, the details of the operation of the calculation process in the tool movement characteristic amount calculation unit 4 will be described for each characteristic amount.

  First, the position of the tool reference point will be described. FIG. 2 is a diagram illustrating a state in which the machining surface 25 including the point of interest 24 is created by the movement of the tool 26 along the movement trajectory segment 21 forming the tool movement trajectory data 7. As shown in FIG. 2, when the tool 26 moves along one of the movement trajectory segments 21 forming the tool movement trajectory data 7 to create a machining surface 25 including the point of interest 24, the cutting edge surface of the tool 26 There is always a moment that passes through the point of interest 24. The coordinate value of the tool reference point 27 at that moment or any one of the coordinate components is a characteristic amount related to the tool movement.

  The tool movement characteristic amount calculation unit 4 performs workpiece shape data 8, tool data 6, and tool movement trajectory with respect to a designated point (point of interest 24) of a designated machining surface 25 requested from the cutting shape display unit 3. The movement locus segment 21 that created the designated machining surface is specified with reference to the data 7. Next, the cutting edge surface of the tool 26 determines the point of interest 24 from the information on the start point and end point of the tool movement described in the specified movement trajectory segment 21 and information on the movement mode between them and the information on the tool shape described in the tool data 6. The position of the tool reference point 27 at the moment of passing is obtained and output to the cutting shape display unit 3 as a characteristic amount of tool movement with respect to the point of interest 24.

  Next, the moving direction of the tool will be described. In FIG. 2, the tool movement direction vector 28 or any component thereof at the moment when the cutting edge surface of the tool 26 passes the point of interest 24 is a characteristic amount related to the tool movement. This is nothing but the tangent vector of the tool movement locus at the position of the tool reference point 27 at that moment.

  The tool movement characteristic amount calculation unit 4 calculates the tool reference point 27 at the moment of passage from the movement information described in the movement locus segment 21 specified by the same method as described above and the tool shape information described in the tool data 6. A position is obtained, a tangent vector of the tool movement trajectory at that position is calculated, and is output to the cutting shape display unit 3 as a characteristic value of the tool movement with respect to the specified point (the point of interest 24). When the movement mode of the specified movement locus segment is linear movement, it is not necessary to obtain the position of the tool reference point 27 at the moment of passing through the specified point, and the direction vector from the movement start point to the end point should be obtained. It becomes a vector.

  Next, the direction of the target point viewed from the tool reference point will be described. The direction vector from the position of the tool reference point 27 to the point of interest 24 at the moment when the cutting edge surface of the tool 26 passes the point of interest 24, or any component thereof, is a characteristic amount related to the tool movement. FIG. 3 is a diagram for explaining the operation of calculating the direction of the target point viewed from the tool reference point as the tool movement characteristic amount. As shown in FIG. 3, the direction vector at this time includes three coordinate directions relative to the traveling direction 31 of the tool 26 (the traveling direction of the tool 26, the axial direction of the tool 26, and the direction orthogonal to both of these directions). (Coordinate component in the coordinate system as an axis) or angle components such as longitude 32 and latitude 33.

  The tool movement characteristic amount calculation unit 4 obtains the position of the tool reference point at the instant of passage from the movement information described in the movement locus segment specified in the same manner and the tool shape information described in the tool data 6. Calculate the direction vector from the tool reference point to the specified point and convert it to a component in the coordinate system based on the tool traveling direction, or convert it to an angle component such as longitude / latitude based on the tool traveling direction. Then, it is output to the cutting shape display unit 3 as a characteristic amount of tool movement with respect to the specified point.

  As described above, according to the present embodiment, on the simulation display screen, the characteristic amount related to the tool movement related to the creation of the machining surface of the workpiece is displayed superimposed on the workpiece shape. And visually understand the causal relationship between creation of machined surfaces. As a result, for example, when a processing flaw occurs on the processing surface, what characteristics regarding tool movement can be obtained by quantitatively analyzing the characteristic amount or the display pattern superimposed on the processing flaw and its peripheral portion. It is possible to estimate whether the occurrence of processing flaws has been greatly affected, and it becomes easy to plan measures for avoiding processing flaws. Therefore, the yield of products manufactured by cutting can be improved.

Embodiment 2. FIG.
FIG. 4 is a diagram showing a configuration of a machining simulation apparatus according to Embodiment 2 of the present invention. In the present embodiment, the machining simulation apparatus core 40 includes first tool movement trajectory data 11, first workpiece shape data 12, second tool movement trajectory data 41, and second workpiece. It differs from the machining simulation apparatus according to the first embodiment shown in FIG. 1 in that the object shape data 42 is stored in the simulation data storage unit 5. In addition, the machining simulation apparatus according to the present embodiment includes a first tool movement characteristic amount calculation unit 14, a second tool movement characteristic amount calculation unit 43, and a tool movement characteristic amount difference calculation unit 44. In the present embodiment, the cutting shape processing unit 2 receives the tool data 6 stored in the simulation data storage unit 5 and the first tool movement trajectory data 11 or the second tool movement trajectory data 41 as input. The tool described by the data 6 is moved along the tool movement locus described by the first tool movement locus data 11 or the second tool movement locus data 41, and the first data stored in the simulation data storage unit 5 is stored. Cutting is simulated by cutting and deforming the workpiece shape data 12 or the second workpiece shape data 42. The first movement trajectory data 11, the first workpiece shape data 12 and the first tool movement characteristic amount calculation unit 14 are the tool movement trajectory data 7 and the workpiece shape data 8 in the first embodiment. And the tool movement characteristic amount calculation unit 4.

  As in the first embodiment, the machining simulation apparatus as a whole has a display device 9 that is a display output destination of the workpiece shape, and a user performs an execution operation of the simulation apparatus and instructs a visual line direction of display. A keyboard, a mouse, and the like are provided as the input device 10.

  The first tool movement trajectory data 11 and the second tool movement trajectory data 41 stored in the simulation data storage unit 5 are (a) tool movement trajectory data extracted from the description in the machining program, and (b) NC machining. Either tool movement trajectory data extracted from a tool movement command to the machine, or (c) tool movement trajectory data extracted from sensing data at the control axis motor end or machine end of the NC machine tool. The first tool movement trajectory data 11 and the second tool movement trajectory data 41 are different types of tool movement extracted from descriptions in the machining program under the same machining condition setting of the same machining program. It is the trajectory data or the same kind of tool movement trajectory data under two different machining condition settings in the same machining program.

  The machining simulation apparatus according to the present embodiment performs cutting simulation shape processing using the cutting shape processing unit 2 based on the first tool movement trajectory data 11 of the simulation data storage unit 5, and the workpiece is being simulated. The shape and the final shape are stored in the simulation storage unit 5 as the first workpiece shape data 12.

  Similarly, based on the second tool movement trajectory data 41 in the simulation data storage unit 5, the cutting shape processing unit 2 is used to perform cutting processing simulation shape processing, and the intermediate shape and final shape of the workpiece are simulated. 2 is stored in the simulation data storage unit 5 as workpiece shape data 42.

  The cutting shape display unit 3 receives the first workpiece shape data 12 as an input, and outputs a projection image along the specified line-of-sight direction of the workpiece shape to the display device 9. In this process, when the data of the pixel point on the projection image corresponding to each point on each processing surface of the first workpiece shape data 12 is determined, the difference in the characteristic amount to be displayed superimposed on that point is calculated. An inquiry is made to the tool movement characteristic amount difference calculation unit 44.

  First, in response to an inquiry from the cutting shape display unit 3, the tool movement characteristic amount calculation unit 44 uses a designated point on the designated machining surface of the first workpiece shape data 12 as a point of interest, and first The tool movement characteristic amount calculation unit 14 is inquired to acquire the tool movement characteristic amount involved in the creation of the point of interest.

  Next, the tool movement characteristic amount difference calculation unit 44 specifies a point on the machining surface of the second workpiece shape data 42 that is located at the shortest distance from the point of interest for the same point of interest. Then, the second tool movement characteristic amount calculation unit 43 is inquired about the specified point on the machining surface, and the tool movement characteristic amount related to creation of the point is acquired. The difference between the two characteristic quantities calculated and acquired in this way is calculated and output to the cutting shape display unit 3.

  FIG. 5 is a diagram illustrating an example of an operation in the tool movement characteristic amount difference calculation unit 44 when the position of the tool reference point is a characteristic amount. As shown in FIG. 5A, the tool movement characteristic amount difference calculation unit 44 receives the point of interest 24 on the machining surface 25 from the first tool movement characteristic amount calculation unit 14 at the moment when the cutting edge surface of the tool 26 passes. The position of the tool reference point 27 is acquired. Next, as shown in FIG. 5B, a point 51 on the machining surface 52 of the second workpiece shape data 42 that is the shortest distance from the point of interest 24 is specified. Then, as shown in FIG. 5C, the position of the tool reference point 54 at the moment when the cutting edge surface of the tool 53 passes the point 51 on the machining surface 52 is acquired from the second tool movement characteristic amount calculation unit 43. . Finally, the difference between the tool reference points 27 and 54 is calculated.

  The cutting shape display unit 3 displays the difference in the characteristic amount calculated by the tool movement characteristic amount difference calculation unit 44 in a superimposed manner on the pixel point being processed. As in the first embodiment, for superimposing the characteristic amount difference on the pixel point, a method is used in which the color determined based on the magnitude of the characteristic amount difference or a positive / negative sign is used as the pixel value of the pixel point. Use. Since the difference in the characteristic amount is superimposed and displayed with the color information, it is easy to visually grasp the feature amount pattern.

  As described above, according to the present embodiment, on the simulation display screen, the difference in the characteristic amount related to the tool movement related to the creation of the machining surface of the workpiece is displayed superimposed on the workpiece shape. The effect of differences in the movement trajectory caused by the characteristics of the machining program itself, the characteristics of the tool movement command generation algorithm in the NC control unit, and the characteristics of the NC machine tool response to the tool movement command on the creation of the machining surface is visually I can grasp. Thereby, for example, when a processing flaw occurs on the surface to be processed, the tool movement command information is obtained by quantitatively analyzing the difference between the processing flaw and the characteristic amount superimposed on the peripheral portion or the display pattern thereof. It is possible to easily determine which processing process that generates the main cause of the processing flaw. Further, by observing the difference in the characteristic amount superimposed and displayed and changing the display pattern by changing the processing condition, it becomes easy to derive an appropriate processing condition for avoiding a processing flaw. Therefore, the yield of products manufactured by cutting can be improved.

  In this embodiment, two types of tool machining trajectory data are required. However, a causal relationship (the tool moves in a specific direction or a specific movement mode) between the way the tool moves and the magnitude of the difference in the characteristic amount. In this case, the difference in the characteristic amount becomes large). For this reason, it becomes easy to specify the cause of the processing flaw.

  As described above, the machining simulation apparatus according to the present invention is useful for analyzing the cause of the occurrence of machining flaws during cutting and avoiding the occurrence of machining flaws.

DESCRIPTION OF SYMBOLS 1, 40 Core part of machining simulation apparatus 2 Cutting shape processing part 3 Cutting shape display part 4 Tool movement characteristic amount calculation part 5 Simulation data storage part 6 Tool data 7 Tool movement locus data 8 Workpiece shape data 9 Display device 10 Input device DESCRIPTION OF SYMBOLS 11 1st tool movement locus data 12 1st workpiece shape data 14 1st tool movement characteristic-value calculation part 21 Movement locus segment 24 Point of interest 25, 52 Machining surface 26, 53 Tool 27, 54 Tool reference point 28 Movement direction vector 41 Second tool movement trajectory data 42 Second workpiece shape data 43 Second tool movement characteristic amount calculation unit 44 Tool movement characteristic amount difference calculation unit 51 Points on the machining surface

Claims (8)

Means for simulating cutting based on tool data indicating the type and shape of the tool and tool movement trajectory data indicating the movement trajectory of the tool to generate shape data indicating the shape of the workpiece;
Regarding the target point on the processed surface of the workpiece in the cutting process, as the characteristic amount related to the tool movement involved in creating the shape of the processed surface of the target point, the position of the tool reference point, the moving direction of the tool, and Means for calculating the direction of the point of interest viewed from the tool reference point based on the shape data, the tool data, and the tool movement trajectory data;
Means for superimposing and displaying the characteristic amount on a projection image of the workpiece along a predetermined viewing direction generated based on the shape data;
A machining simulation apparatus that supports estimation of a cause of machining failure based on a display pattern of the characteristic amount displayed in a superimposed manner. Based on the tool data indicating the type and shape of the tool and the first and second tool movement trajectory data indicating the movement trajectory of the tool, the first and second simulations are performed to indicate the shape of the workpiece. Means for generating shape data;
As a first characteristic amount relates to a tool movement involved in the creation of the shape of the processed surface of the first target point on the machined surface of the workpiece of the middle of the cutting or after the end showing the first shape data , The position of the first tool reference point, the moving direction of the first tool, and the direction of the first point of interest viewed from the first tool reference point , the first shape data, the tool data, and the first Means for calculating based on the tool movement trajectory data;
As a second characteristic amount relates to a tool movement involved in the creation of the second shape of the processed surface of the second target point on the working surface of said workpiece after the machining middle or end indicated shape data , The position of the second tool reference point, the moving direction of the second tool, and the direction of the second point of interest as viewed from the second tool reference point , the second shape data, the tool data, and the second Means for calculating based on the tool movement trajectory data;
Means for calculating a difference between the first characteristic quantity and the second characteristic quantity;
Means for superimposing and displaying the difference between the first characteristic amount and the second characteristic amount on a projection image of the workpiece along a predetermined line-of-sight direction generated based on the shape data And
The second tool movement trajectory data and the first tool movement trajectory data are based on the trajectory data obtained from the description of the machining program under the same machining condition setting of the same machining program, based on the machining program. The trajectory data obtained from the control signal to the machine tool performing the cutting process and the trajectory data obtained based on the output of the sensor installed in the machine tool, or It is the same type of trajectory data under two different machining conditions of the same machining program,
A machining simulation apparatus that supports estimation of a cause of machining failure based on a display pattern of a difference between the first characteristic quantity and the second characteristic quantity displayed in a superimposed manner. Based on the tool data including the type and shape of the tool, and tool movement trajectory data indicating the movement trajectory of the tool, a machining simulation method for simulating a change in the shape of the workpiece by cutting,
Generating shape data indicating the shape of the workpiece in the course of the cutting based on the tool data and the tool movement trajectory data;
Regarding the target point on the processed surface of the workpiece, the characteristic amount related to the tool movement involved in the creation of the shape of the processed surface of the target point, as viewed from the position of the tool reference point, the tool moving direction, and the tool reference point Calculating the direction of the point of interest based on the shape data, the tool data, and the tool movement trajectory data;
A step of superimposing and displaying the characteristic amount on a projection image of the workpiece along a predetermined line-of-sight direction generated based on the shape data of the workpiece,
A machining simulation method characterized by supporting estimation of a cause of machining failure based on a display pattern of the characteristic amount displayed in a superimposed manner.   4. The characteristic amount is at least one of a position of a tool reference point preset for the tool, a moving direction of the tool, and a direction of the point of interest viewed from the tool reference point. The machining simulation method described.   5. The machining simulation method according to claim 3, wherein the point of interest on the projected image of the workpiece is displayed in a color predetermined based on the size and sign of the characteristic amount. A machining simulation method for simulating a change in the shape of a workpiece by cutting based on tool data including the type and shape of the tool and first and second tool movement locus data indicating the movement locus of the tool Because
Generating, based on the tool data and the first tool movement trajectory data, first shape data indicating the shape of the workpiece in the cutting process;
As the first characteristic amount related to the tool movement involved in creating the shape of the processing surface of the first target point, the first characteristic point on the processing surface of the workpiece indicated by the first shape data , The position of the first tool reference point, the moving direction of the first tool, and the direction of the point of interest viewed from the first tool reference point are represented by the first shape data, the tool data, and the first tool moving locus. Calculating based on the data;
Generating second shape data indicating a shape of the workpiece in the cutting process based on the tool data and the second tool movement trajectory data;
As the second characteristic amount related to the tool movement involved in creating the shape of the processing surface of the second target point, the second characteristic point on the processing surface of the workpiece indicated by the second shape data , position of the second tool reference point, the direction of the attention point as viewed from the direction of movement and the second tool reference point of the second tool, said second shape data, the tool data and the second tool moving locus Calculating based on the data;
Calculating a difference between the first characteristic amount and the second characteristic amount;
A difference between the first characteristic amount and the second characteristic amount is superimposed on a projection image of the workpiece along a predetermined line-of-sight direction generated based on the shape data of the workpiece. And displaying the
The second tool movement trajectory data and the first tool movement trajectory data are based on the trajectory data obtained from the description of the machining program under the same machining condition setting of the same machining program, based on the machining program. The trajectory data obtained from the control signal to the machine tool performing the cutting process and the trajectory data obtained based on the output of the sensor installed in the machine tool, or It is the same type of trajectory data under two different machining conditions of the same machining program,
A machining simulation method characterized by supporting estimation of a cause of machining failure based on a display pattern of a difference between the first characteristic quantity and the second characteristic quantity displayed in a superimposed manner.   The first characteristic amount is at least one of a position of a tool reference point preset in the tool, a moving direction of the tool, and a direction of the first point of interest viewed from the tool reference point, The second characteristic amount is at least one of a position of a tool reference point preset for the tool, a moving direction of the tool, and a direction of the second focus point as viewed from the tool reference point. The machining simulation method according to claim 6.   The point of interest on the projected image of the workpiece is displayed with a color predetermined based on the magnitude and sign of the difference between the first characteristic quantity and the second characteristic quantity. The machining simulation method according to claim 6 or 7.

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