MACHINING SIMULATION DISPLAY APPARATUS AND MACHINING SIMULATION DISPLAY METHOD

A machining simulation display apparatus displays, on a display screen, an image of a shape of a workpiece and a shape of a tool that machines the workpiece, and includes a display update unit to provide a command to combine, at a change point on a trajectory of the tool, an image of the shape of the tool displayed on the display screen and an image of the shape of the workpiece at a first display update timing at which the image displayed on the display screen is updated or at a second display update timing that is a time point after a lapse of a constant display update interval since the first display update timing, the change point being present between the first display update timing and the second display update timing.

The present invention relates to a machining simulation display apparatus and a machining simulation display method for simulating the machining of a workpiece with a machine tool.

BACKGROUND

To machine workpieces that are machining targets by using machine tools that are driven by numerical central (NC) devices, a machining simulation is used in which images reproducing a workpiece and a tool attached to the machine tool are displayed on the display screen as an aid to the operations for testing machining programs. Computer aided manufacturing (CAM) systems for creating machining programs or NC devices that execute machining programs to control machine tools often have a function that performs the machining simulation.

By performing the machining simulation, the operator understands, from the displayed animations, the process of machining a workpiece and the process of moving a tool so as to inspect for machining errors, such as excessive cutting or insufficient cutting, and to further inspect whether the tool makes any unintentional movement. Displaying during the machining simulation is updated at certain time intervals or every time a tool movement command has been issued a certain number of times. In recent years, machining of parts with complicated shapes has become common due to improvements in the function and performance of machine tools. This has resulted in a tendency for machining programs to increase in size and to become more complicated. Consequently, the operator cannot follow complicated movements of the tools and thus it becomes difficult for the operator to perform a testing operation. This is becoming more and more of a problem.

To address such a problem, the operation simulation device in Patent literature 1 displays, on a display unit, trajectory figures and arrow figures, which exhibit the characteristics of trajectories of movable objects such as tools, in a superimposed manner so as to make it easier for the operator to follow the trajectories of movable objects.

CITATION LIST

Patent Literature

SUMMARY

Technical Problem

With the method of displaying, on the display unit, figures indicating the trajectories of movable objects and relevant information in a superimposed manner as disclosed in Patent Literature 1, there is, however, a problem in that visibility of a workpiece and a tool, which are what should actually be displayed degrades and this makes it difficult for the tool trajectory to be intuitively understood. It is possible to shorten the display update interval, so as to smoothly display animations and thus make it easier for the operator to follow the tool trajectory. This however causes another problem in that it becomes difficult to determine the display update interval, appropriate for preventing excessive overhead in a display updating process from occurring.

The present invention has been achieved in view of the above and an object of the present invention is to provide s machining simulation display apparatus that enables the tool trajectory during simulation to be easily followed.

Solution to Problem

In order to solve the above problems; and achieve the object, a machining simulation display apparatus according to an aspect of the present invention is a machining simulation display apparatus that displays, on a display screen, an image of a shape of a workpiece and a shape of a tool that machines the workpiece, the apparatus including: a display update unit to update, at a change point on a trajectory of the tool, an image of the shape of the tool, displayed on the display screen, at a position of the change point and with a posture at the change point, the change point being present between a first display update timing at which the image displayed on the display screen is updated and a second display update timing that is a time point after a lapse of a constant display update interval since the first display update timing.

Advantageous Effects of Invention

According to the machining simulation display apparatus of the present invention, an effect is obtained where the tool trajectory during simulation can be easily followed. Specifically, with the machining simulation display apparatus of the present invention, displaying is additionally updated only at a change point on the tool trajectory with the display update interval being kept. long; therefore, the problems with the conventional technologies, such as excessive display updating processes caused by finely displaying the progress of the movement along the trajectory and degradation of visibility, can be solved, which means that the tool trajectory can be easily followed.

DESCRIPTION OF EMBODIMENTS

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

First Embodiment

FIG. 1is a diagram illustrating a functional configuration of a machining simulation display apparatus according to a first embodiment of the present invention.FIG. 2is a diagram illustrating an example of a workpiece to be machined and a machine tool for which a machining program is to be tested. In the following descriptions, a workpiece and a machine tool for which a machining program is to be tested will be briefly described with reference toFIG. 2and then the function of a machining simulation display apparatus100according to the first embodiment of the present invention will be described in detail with reference toFIG. 1. Hereinafter, the machining simulation display apparatus100is simply referred to as “machining simulator100” in some cases.

FIG. 2illustrates the appearance of a machine tool200, which is an example of an orthogonal three-axis vertical machine tool. The machine tool200includes a mount21; a saddle22that is placed on the mount21and is moved in the y-axis direction; a work table23that is placed on the saddle22; and a column24that is fixed to the mount21and extends upward from the mount21. A ram25is attached to the column24and a workpiece300, which is to be machined, is placed on the work table23.

The machine tool200illustrated inFIG. 2further includes an x-axis driving mechanism26xthat is an actuator that is attached to the saddle22and moves the work table23in the x-axis direction; a y-axis driving mechanism26ythat is an actuator that is attached to the mount21and moves the saddle22in the y-axis direction; and a x-axis driving mechanism26zthat is an actuator that is attached to the column24and moves the ram25in the z-axis direction.

The x-axis driving mechanism26xincludes an x-axis motor27x;a feed shaft28z.driven by the x-axis motor27x;and a rotation-angle detector29xthat detects the rotation angle of the feed shaft23x.The y-axis driving mechanism26yincludes a y-axis motor27y;a feed shaft28ydriven by the y-axis motor27y;and a rotation-angle detector22ythat detects the rotation angle of the feed shaft28y.The x-axis driving mechanism26zincludes a z-axis motor21z;a feed shaft28zdriven by the x-axis motor27z;and a rotation-angle detector29zthat detects the rotation angle of the feed shaft28z.Examples of the machine tool include, other than the orthogonal three-axis vertical machine tool illustrated as an example inFIG. 2, a four-axis machine tool and a five-axis machine tool that further include a rotation shaft for changing the tool posture; however, the present invention can be used for any type of machine tool without being limited to these examples.

The x-axis driving mechanism26xmoves the work table23, and the y-axis driving mechanism26ymoves the saddle22and the x-axis driving mechanism26xplaced on the top of the saddle22. The z-axis driving mechanism26attached to the column24moves the ram25and a spindle30, and the workpiece300is machined by a tool31attached to the tip of the spindle30. As a result, with the combination of two degrees of freedom in movement of the workpiece300in the xy plane and one degree of freedom in movement of the tool31in the s-axis direction, the material of the workpiece300is removed from its surface at the portion where the tool31intersects with the workpiece300in the xyz space or three-dimensional space, i.e., with three degrees of freedom. Consequently, a three-dimensional shape is created.

The machining simulator100illustrated inFIG. 1is an apparatus that simulates machining of the workpiece300performed by the machine tool200illustrated inFIG. 2. The machining simulator100includes a workpiece shape processing unit1that performs an updating process of workpiece shape data11on the basis of the tool movement commands described in machining program data10and a workpiece shape display unit2that, upon receiving the workpiece shape data11, performs a projection process in accordance with a projection display parameter12and generates and outputs workpiece display image data13.

The machining program data10is data that describes a plurality of tool movement commands that are movement commands for the tool31inFIG. 2, which is the subject of the machining simulation. The workpiece shape processing unit1simulates machining by moving, on the basis of the tool movement commands described in the machining program data10, the three-dimensional shape model represented by tool shape data14and by sequentially changing the three-dimensional shape model represented by the workpiece shape data11. Specifically, the workpiece shape processing unit1repeats the process of analyzing each of the tool movement commands; calculating the area in which the three-dimensional shape model represented by the workpiece shape data11intersects with the three-dimensional swept shape obtained by continuously moving the three-dimensional shape model represented by the tool shape data14along a curve according to the movement mode from the start point to the end point of the movement; and updating the workpiece shape data11with the data obtained by subtracting the intersection area from the three-dimensional shape model represented by the workpiece shape data11.

The workpiece shape data11is data obtained by simulating, with a three-dimensional shape model, the instantaneous shape of the workpiece300from the machining start position to the machining end position. The workpiece display image data13is image data for a workpiece obtained by projecting the three-dimensional shape model represented by the workpiece shape data11in accordance with the projection display parameter12. The workpiece display image data13is a combination of color data representing brightness and color of pixels and depth data representing the depth information for the projection.

The machining simulator100further includes a tool shape display unit3that performs, on the basis of the position and posture of the tool at a designated time point during the machining simulation, a projection process or; the three-dimensional shape model represented by the tool, shape data14in accordance with the projection display parameter12and then outputs tool, display image data15. The tool shape data14is data obtained by simulating the shape of the tool31by using a three-dimensional shape model. The tool display image data25is a display image obtained by projecting the three-dimensional shape model represented by the tool shape data14in accordance with the projection display parameter12. The tool display image data15is a combination of color data representing brightness and color or pixels and depth data representing the depth information for the projection.

The machining simulator100further includes a display image combining unit4that, on the basis of the workpiece display image data13and the tool display image data15, combines a workpiece shape image and a tool shape image to generate and output combined display image data16for displaying, on a display screen400, the combined image of the workpiece shape image and the tool shape image. The combined display image data16is image data obtained by performing a hidden surface elimination process on the workpiece display image data13and the tool display image data15by using z-buffering. The combined display image data16is output to the display screen400connected to the machining simulator100. The display screen400displays, on the basis of the combined display image data16, an image that reproduces the shapes of the workpiece300and the tool31illustrated inFIG. 2.

The machining simulator100further includes a display update unit5that updates an image of the shape of the tool displayed on the display screen400at a change point on the tool trajectory between the first display update timing at which an image displayed on the display screen400is updated and the second display update timing that is a time point after the lapse of a constant display update interval since the first display update timing. The display update unit5outputs an execution command5ato cause the workpiece shape display unit2, the tool shape display unit3, and the display image combining unit4to update image data at the time when the display update interval has elapsed. Examples of the time when the display update interval has elapsed include a time point when a certain period of time has elapsed and a time point when a certain number of tool movement commands among a plurality of tool movement commands have been executed.

The display update unit5includes a control unit51and a storage unit52. The control unit51detects the position at which a translational axis or a rotational axis of the machine tool is reversed on the tool trajectory between the first display update timing and the second display update timing during simulation based on the tool movement commands described in the machining program data10. Hereinafter, the position at which a translational axis or a rotational axis is reversed is in some cases referred to as a change point or an intermediate point. The period of time between the first display update timing and the second display update timing corresponds to the display update interval described above. The feed shafts28x,28y,and23zillustrated inFIG. 2are translational axes. The rotational, axis is an axis for changing the direction of a tool shaft in a four-axis or five-axis machine tool. The control unit51stores, in the storage unit52as tool intermediate point data17, the position and posture of the cool at a position at which a translational axis or a rotational axis is reversed.

When there are one or a plurality of pieces of the tool intermediate point data17at intermediate points between the first display update timing and the second display update timing, the control unit51controls the tool shape display unit3on the basis of the position and posture of the tool at the one or a plurality of intermediate points. Consequently, the tool display image data15at the intermediate point(s) is generated in the tool shape display unit3. The display image combining unit4combines a workpiece shape image and a tool shape image at an intermediate point on the basis of the tool display image data15and the workpiece display image data13at the intermediate point so as to generate the combine display image data16.

After the tool display image data15is generate for all the tool intermediate points, the control unit51outputs the execution command5a at the second display update timing. Consequently, the tool display image data15at the second display update timing is generated in the tool shape display unit3and the display image combining unit4combines a workpiece shape image and a tool shape image at the second display update timing on the basis of the tool display image data15arid the workpiece display image data13at the second display update timing so as to generate the combined display image data16.

FIG. 3is a diagram, describing the first display update timing, the second display update timing, and the display update interval in the control unit illustrated inFIG. 1. As described above, a display update interval T is preset in the control unit51. In the present embodiment, first display update timing t1and second display update timing t2each indicate the time point after the lapse of the display update interval T. The second display update timing t2represents the latest display update time point in a time sequence, i.e., the present display update time point. The first display update timing t1represents the previous display update time point, i.e., the display update time point that precedes the second display update timing t2by the display update interval T.

An operation performed by the machining simulator100will be described next.

FIG. 4is a diagram illustrating the workpiece, the tool, and the tool trajectory displayed on the display screen illustrated inFIG. 1.FIG. 4illustrates a tool shape image31A and a workpiece shape image300A updated at the first display update timing t1illustrated inFIG. 3.

The workpiece shape image300A is an image displayed on the display screen400on the basis of the workpiece display image data13generated by the workpiece shape display unit2illustrated inFIG. 1and it is an image obtained by simulating the shape of the workpiece300illustrated inFIG. 2. The tool shape image31A is an image displayed on the display screen400on the basis of the tool display image data15generated by the tool shape display unit3illustrated inFIG. 1and it is an image obtained by simulating the shape of the tool31illustrated inFIG. 2.

A tool trajectory40indicated by a dotted line represents the trajectory of the tool shape image31A during simulation and specifically represents a virtual trajectory of the tool shape image31A between the first display update timing t1and the second display update timing t2illustrated inFIG. 3. A first intermediate point41and a second intermediate point42on the tool trajectory40are positions described above at which a translational axis or a rotational axis is reversed. In the first embodiment of the present invention, the first, intermediate point41and the second intermediate point42cannot be individually deemed as forming a reversal; however, they form a reversal in a broader sense on the tool trajectory40between the first display update timing t1and the second display update timing t2.

FIG. 5is a diagram illustrating examples of an image updated by the machining simulation display apparatus according to the first embodiment of the present invention.FIG. 5(a)illustrates an example of how the tool shape image31A and the workpiece shape image300A updated at the first display update timing t1are displayed on the display screen400.FIG. 5(b)illustrates an example of how the tool shape image31A and the workpiece shape image300A updated at the first intermediate point41are displayed on the display screen400.FIG. 5(c)illustrates an example of how the tool shape image31A and the workpiece shape image300A updated at the second intermediate point42are displayed on the display screen400.FIG. 5(d)illustrates an example of how the tool shape image31A and the workpiece shape image300A updated at the second display update timing t2are displayed on the display screen400. The display images inFIGS. 5(b) and (c)correspond to display images at the time when a translational axis or a rotational axis is reversed.

In the machining simulator100according to the first embodiment, display images updated at intermediate points are inserted between the display image updated at the first display update timing t1and the display image updated at the second display update timing t2; therefore, the operator of the machining simulator100can visually recognize the tool trajectory between the first display update timing t1and the second display update timing t2.

FIG. 6is a flowchart describing an operation performed by the machining simulation display apparatus according to the first embodiment of the present invention. The machining simulator100generates the workpiece display image data13and the tool display image data15at the first display update timing t1. The machining simulator100combines a tool shape image and a workpiece shape image at the first display update timing t1on the basis of the workpiece display image data13and the tool display image data15generated at the first display update timing t1(Step311). The data for the combined image is sent as the combined display image data16to the display screen400. The image displayed or the display screen400at this time point corresponds to the image inFIG. 5(a).

Next, the machining simulator100analyzes the tool trajectory between the first display update timing t1and the second display update timing t2. If there is a position at which a translational axis or a rotational axis is reversed, i.e., an intermediate point (Yes at Step S12), the machining simulator100stores, as the tool intermediate point data17, the position and posture of the tool at a position at which a translational axis or a rotational axis is reversed in the storage unit52(Step S13).

At Step S12, if there is no intermediate point (No at Step S12), the machining simulator100performs the process at Step S17.

At Step S14, the machining simulator100refers to the tool intermediate point data17stored in the storage unit52and determines whether the tool display image data15corresponding to ail the pieces of the tool intermediate point data17has been generated.

If the tool, display image data15corresponding to any one or more pieces of the tool intermediate point data17has not been generated (No at Step S14), the machining simulator100generates the tool, display image data15corresponding to each intermediate point (Step S15).

The machining simulator100combines a tool shape image at each intermediate point and a workpiece shape image at the second display update timing t2on the basis of the tool display image data15at a corresponding intermediate point and the workpiece display image data13at the second display update timing t2(Step S16). The data for the combined images is sent as the combined display image data16to the display screen400. The images displayed on the display screen400in this case correspond to the images inFIG. 5(b)andFIG. 5(c).

At Step S14, if the tool display image data15corresponding to all the pieces of tool intermediate point data17has been generated (Yes at Step314), the machining simulator100generates the workpiece display image data13and the tool display image data15at the second display update timing t2(Step S17).

The machining simulator100generates, on the basis of the tool display image data15and the workpiece display image data13at the second display update timing t2, the combined display image data16in which the workpiece shape image and the tool shape image at the second display update timing t2are combined, and it then outputs the combined display image data16to the display screen400(Step S18). The machining simulator100then ends the display update process. The image displayed on the display screen400at this time point corresponds to the image inFIG. 5(d).

As described above, with the machining simulator100according to the first embodiment, the operator can easily follow the tool trajectory between the first display update timing t1and the second display update timing t2. Thus, any unintentional machining operation can be easily found. Moreover, with the machining simulator100according to the first embodiment., it is possible to minimise additional overhead during the machining simulation display process for the period of time between the first display update timing t1and the second display update timing12.

Second Embodiment

In the first embodiment, a description is given of an exemplary configuration in which the tool display image data15generated at an intermediate point is combined with the workpiece display image data13generated at the second display update timing t2. Combining the tool display image data35generated at an intermediate point with the workpiece display image data13generated at the first display update timing t1can also produce a similar effect to that of the first embodiment. In the second embodiment, a description will be given of an exemplary configuration in which displaying based on the tool display image data15at an intermediate point is updated by using the workpiece display image data13generated at the first display update timing t1. The machining simulator100according to the second embodiment has a functional configuration similar to that of the machining simulator100illustrated inFIG. 1, but it performs an operation different from that performed by the machining simulator100illustrated inFIG. 1. The operation performed by the machining simulator100according to the second embodiment will be described below with reference toFIGS. 7 and 3.

FIG. 7is a diagram illustrating examples of an image updated by a machining simulation display apparatus according to the second embodiment of the present Invention.FIG. 7(a)illustrates an example of how the tool shape image31A and the workpiece shape image300A updated at the first display update timing t1are displayed on the display screen400.FIG. 7(b)illustrates an example of how the tool shape image31A and the workpiece shape image300A updated at the first intermediate point41are displayed on the display screen400.FIG. 7(c)illustrates an example of how the tool shape image31A and the workpiece shape image300A updated at the second intermediate point42are displayed on the display screen400. When the tool shape image31A is updated at an intermediate point as illustrated inFIG. 7(b)andFIG. 7(c), the machining simulator100according to the second embodiment uses the workpiece shape image300A updated at the first display update timing t1.FIG. 7(d)illustrates an example of how the tool shape image32A and the workpiece shape image30GA updated at the second display update timing t2are displayed on the display screen400. The display images inFIGS. 7(b) and (c)correspond to display images at the time when a translational axis or a rotational axis is reversed.

FIG. 3is a flowchart describing an operation performed by the machining simulation display apparatus according to the second embodiment of the present invention. Step S21to Step S23illustrated inFIG. 8respectively correspond to Step S11to Step S18illustrated inFIG. 6. The processing details at Step S26are however different from those at Step S16in the flowchart illustrated inFIG. 6. The processing details at steps other than Step S26ate the same as those at steps other than Step S16in the first embodiment, and a duplicated description thereof is omitted in the second embodiment.

At Step S16illustrated inFIG. 6, a tool shape image at each intermediate point and a workpiece shape image at the second display update timing t1are combined on the basis of the tool display image data15at a corresponding intermediate point and the workpiece display image data13at the second display update timing t2. In contrast, at Step S26illustrated inFIG. 8, a tool shape image at each intermediate point and a workpiece shape image at the first display update timing t1are combined on the basis of the tool display image data15at a corresponding intermediate point and the workpiece display image data13at the first display update timing t1. The data for the combined images is sent as the combined display image data16to the display screen400. The images displayed on the display screen400in this case correspond to the images inFIG. 7(b)andFIG. 7(c).

Because the shape of a workpiece is complicated compared with the shape of a tool, the process of generating a display image of a workpiece consumes more time than the process of generating a display image of a tool. In order to shorten the processing time required for generating a display image of a workpiece, the machining simulator100according to the second embodiment is configured to display, on the display screen400, an image obtained by combining a tool shape image at each intermediate point and a workpiece shape image at the first display update timing t1. With this configuration, the processing time required for generating a display image of a workpiece can be shortened. Moreover, the operator can easily follow the tool trajectory; therefore, an operation for testing a machining program becomes easy.

The display screen400illustrated inFIG. 1may be an image display unit installed in a display device (not illustrated) external to the machining simulator100or it may be an image display unit installed in the machining simulator100.

FIG. 9is a diagram illustrating an exemplary configuration of hardware implementing the machining simulation display apparatuses according to the first and second embodiments of the present invention. The machining simulation display apparatus100includes a display unit60, a memory61, a processor62, and an input/output unit63. The processor62uses received data to cause software to execute calculations and control. The memory61stores received data and moreover stores data and software necessary for the processor62to execute calculations and control. The machining program data10and the tool shape data14are input to the input/output unit63. The input/output unit63outputs the combined display image data16to the display screen400. The display unit60corresponds to the display screen400of the machining simulator100. The workpiece shape processing unit1, the workpiece shape display unit2, the tool shape display unit3, the display image combining unit4, and the display update unit5illustrated inFIG. 1are implemented by storing programs for implementing the functions of these components in the memory61and by causing the processor62to execute the programs.

The machining simulation display method according to the present embodiment is a machining simulation display method performed by a machining simulation display apparatus that displays, on a display screen, an image of the shape of a workpiece and the shape of a tool that machines the workpiece. The machining simulation display method according to the present embodiment includes a change point, determining step of determining a change point on the tool trajectory between the first display update timing at which an image displayed on the display screen is updated and the second display update timing that is a time point after the lapse of a constant display update interval since the first display update timing. The machining simulation display method according to the present, embodiment further includes a first displaying step of combining an image of the shape of the workpiece updated at the first display update timing and an image of the shape of the tool updated at the change point on the tool trajectory and displaying a combined image on the display screen; and a second displaying step of combining an image of the shape of the workpiece updated at the second display update timing and an image of the shape of the tool updated at the second display update timing and displaying a combined image on the display screen. With the machining simulation display method according to the present embodiment, the processing time required for generating a display image of a workpiece can be shortened. Moreover, the operator can easily follow the tool trajectory; therefore, an operation for testing a machining program becomes easy.

FIG. 10is a diagram illustrating another example of change points on the tool trajectory according to the first and second embodiments of the present invention. The change point in the first and second embodiments of the present invention may be, instead of the start point and end point of each of the tool movement commands that constitute the tool trajectory, a point43that is an intermediate point of an arc movement command and at which a translational axis is reversed across quadrants; a point44at which the shape of the tool trajectory changes from a line to an arc; or a point45at which the shape of the tool trajectory changes from an arc to a line as illustrated inFIG. 10.

The configurations described in the foregoing embodiments are merely examples of aspects of the present invention. These configurations may be combined with other known technologies, and moreover, part of such configurations may be omitted or modified without departing from the spirit of the present invention.

REFERENCE SIGNS LIST

1workpiece shape processing unit;2workpiece shape display unit;3tool shape display unit;4display image combining unit;5display update unit;5aexecution command;10machining program data;11workpiece shape data;12projection display parameter;13workpiece display image data;14tool shape data;15tool display image data;16combined display image data;17tool intermediate point data;21mount;22saddle;23work table;24column;25ram;26xx-axis driving mechanism;26yy-axis driving mechanism;26zz-axis driving mechanism;27xx-axis motor;27yy-axis motor;27zz-axis motor;26x,28y,28zfeed shaft;29x,29y,29zrotation-angle detector;30spindle;31tool;31A tool shape image;40tool trajectory;41first intermediate point;42second intermediate point;43point that is an intermediate point of an arc movement command and at which a translational axis is reversed across quadrants;44point at which the shape of the tool trajectory changes from line to arc;45point at which the tool trajectory changes from arc to line;51control unit;52storage unit;60display unit;61memory;62processor;63input/output, unit;100machining simulation display apparatus;200machine tool;300workpiece;300A workpiece shape image;400display screen.