Simulators and Simulation Programs

Abstract

This makes it easier to predict interference between the tool and the workpiece, which can be a problem in actual machining. [Solution] The simulator simulates the machining of a workpiece using a tool used in a numerically controlled machine tool and has a virtual data storage unit that stores data of a virtual space including a workpiece model and a tool model; a setting unit that sets a contact warning area on a part of the surface of the tool model; a machining control unit that moves the workpiece model and the tool model in stages based on a numerical control program and controls simulated machining to remove the area of ​​interference between the workpiece model and the tool model; and a detection unit that detects when the contact warning area interferes with the workpiece model during the staged movement in the machining control unit.

Description

[Technical Field]

[0001] The present invention relates to a simulation technique for NC programs (Numerical Control). [Background technology]

[0002] In recent years, there has been an increase in the number of cases where complex machining is performed using NC machine tools that operate with numerical control programs. Using the correct numerical control program ensures accurate machining and high production efficiency.

[0003] Simulators are often used to verify numerical control programs. Simulators simulate machining processes using three-dimensional modeling. The tool model and workpiece model are moved in virtual space, and any parts that interfere with the tool model are removed from the workpiece model, allowing the change in workpiece shape to be observed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-36309 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-95877 [Patent Document 3] Japanese Patent Application Laid-Open No. 2012-218111 Summary of the Invention [Problem to be solved by the invention]

[0005] One of the roles of simulation is to detect interference that is not intended by the operator. For example, Patent Documents 1 to 3 disclose simulation techniques for avoiding interference between the holder that attaches the tool and the workpiece. While collision of the holder with the workpiece should be avoided, if there is an error in the numerical control program, such interference can occur. The above simulation techniques are based on the idea of ​​predicting this.

[0006] However, the above simulation technology does not take into account whether or not the tool and workpiece will interfere with each other, and is based on the assumption that the operator has created a numerical control program based on how the tool should be placed against the workpiece.

[0007] Even when generating numerical control programs using CAD (Computer Aided Design) and CAM (Computer Aided Manufacturing), tool usage is not always taken into consideration. Therefore, even if an inexperienced worker generates a numerical control program that uses tools incorrectly, the problem may not be detected in a simulation. As such, it is difficult to predict interference between the tool and the workpiece, which can cause problems in actual machining.

[0008] To avoid this problem, it is necessary to visually check the operation of the simulation or actual machine. However, depending on the shape of the processed product and the worker's viewpoint, it may be difficult to check visually, and there is a possibility that something may be overlooked. Also, there is an aspect that has to depend on the ability of the worker checking. [Means for solving the problem]

[0009] In one aspect of the present invention, a simulator is characterized by having a virtual data memory unit that simulates the machining of a workpiece by a tool used in a machine tool that operates based on a numerical control program and stores data of a virtual space including a workpiece model and a tool model; a setting unit that sets a contact warning area on a part of the surface of the tool model; a machining control unit that moves the workpiece model and the tool model in stages based on the numerical control program and controls simulated machining to remove the range of interference between the workpiece model and the tool model; and a detection unit that detects when the contact warning area interferes with the workpiece model during the staged movement in the machining control unit.

[0010] A simulation program in one aspect of the present invention is characterized in that it has a computer that performs a simulation using virtual space data including a work model and a tool model for machining a workpiece using a tool used in a machine tool that operates based on a numerical control program, and that the computer has the following functions: a setting function that sets a contact attention area on a part of the surface of the tool model; a machining control function that controls simulated machining by gradually moving the workpiece model and the tool model based on the numerical control program and removing the range of interference between the workpiece model and the tool model; and a detection function that detects when the contact attention area interferes with the workpiece model during the gradually moving process in the machining control function. [Effects of the Invention]

[0011] According to the present invention, it becomes easier to predict interference between a tool and a workpiece, which can be a problem in actual machining. [Brief explanation of the drawings]

[0012] [Figure 1] Fig. 1(A) is a side view of an end mill, and Fig. 1(B) is a side view of a ball end mill. [Figure 2] Figure 2(A) is an image of the virtual space in which the end mill model during machining is viewed from diagonally above, and Figure 2(B) is an image of the virtual space in which the end mill model is viewed from diagonally below. [Figure 3] Fig. 3(A) is a diagram showing a contact warning region set on the side of an end mill model, and Fig. 3(B) is a diagram showing an operation screen. [Figure 4] Figure 4(A) is an image of the virtual space of the ball end mill model during machining, and Figure 4(B) is an image of the virtual space when the ball end mill model is viewed from diagonally below. [Figure 5] FIG. 2 is a functional block diagram of a simulator. [Figure 6] 10 is a processing flow of the simulator. [Figure 7] 10 is a processing flow of the simulator. [Figure 8] FIG. 10 is a diagram showing an operation screen in Modification 1. [Figure 9] FIG. 10 is a diagram showing an operation screen in Modification 2. [Figure 10] Fig. 10(A) is a perspective view of a face mill, and Fig. 10(B) is an image diagram of a virtual space in which the face mill model is viewed from diagonally below. [Figure 11] Fig. 11(A) is a perspective view of a tool bite, Fig. 11(B) is a diagram showing an operation screen in Modification 5, and Fig. 11(C) is a diagram showing a cautionary contact area of ​​a tool bite model. DETAILED DESCRIPTION OF THE INVENTION

[0013] A simulator according to an embodiment will be described below with reference to the drawings. The simulator simulates workpiece machining using a tool in an NC machine tool that operates based on a numerical control program. The numerical control program is an example of a machining program.

[0014] NC machine tools include, for example, machining centers or NC milling machines that machine workpieces by applying a rotating tool to the workpiece, turning centers or NC lathes that machine workpieces by applying a cutting tool to the rotating workpiece, and multitasking machines that combine these functions. Machining centers and NC milling machines perform "turning" by fixing the workpiece and rotating the tool, while turning centers and NC lathes perform "turning" by applying the tool to the rotating workpiece.

[0015] A simulator is realized by having a computer perform the functions defined in a simulation program. The computer that serves as the simulator can be a computer separate from the NC machine tool (for example, a personal computer), or it can be a computer installed inside the NC machine tool. In what follows, a computer separate from the NC machine tool will be referred to as a "desktop simulator," and one inside the NC machine tool will be referred to as an "on-machine simulator."

[0016] The simulator on the actual machine simulates each step before executing the step-by-step machining process on the NC machine tool. If the simulation determines that caution is required, the actual machining can be temporarily suspended.

[0017] In the following, an example of a machining center will be described, and the same components will be denoted by the same reference numerals.

[0018] FIG. 1A is a side view of the end mill 100. FIG. The end mill 100 shown in the figure is a type of rotary tool used in a machining center, and more broadly, a type of cutting tool. The front of the end mill 100 is a cutter 104, and the rear of the end mill 100 is a shank 106. The cutter 104 has a blade on its side (surface parallel to the central axis) for cutting a workpiece (not shown). The front of the cutter 104 (surface perpendicular to the central axis) is provided with an end cutting edge. The shape of the end cutting edge varies for purposes such as leveling the workpiece surface or improving chip escape, but neither shape is suitable for drilling (vertical feed machining).

[0019] The shank 106 is clamped in a chuck of the holder 200 and fixed to the holder 200. When the holder 200 is attached to a spindle (not shown) of a machine tool, the end mill 100 can rotate integrally with the spindle. When the machine tool rotates the spindle and brings a portion of the cutter 104 into contact with a workpiece, the rotating blade cuts off the workpiece in contact with it.

[0020] The numerical control program defines the operation of bringing the rotating cutter 104 into contact with the workpiece, and the machine tool performs cutting in accordance with the design of the processed product in accordance with the numerical control program.

[0021] Normally, the holder 200 does not hit the workpiece. Therefore, if the holder 200 hits the workpiece as a result of operating according to the numerical control program, it means that the numerical control program defines an incorrect operation. In that case, the user needs to correct the numerical control program.

[0022] FIG. 1B is a side view of the ball end mill 102. The ball end mill 102 is a type of rotary tool used in a machining center, and more broadly, a type of cutting tool. Like the end mill 100, the ball end mill 102 includes a cutter 104 and a shank 106. Like the end mill 100, the ball end mill 102 is held in a holder 200 during use.

[0023] The end mill 100 and the ball end mill 102 differ in the shape of the tip of the cutter 104. The tip of the ball end mill 102 is roughly hemispherical. The ball end mill 102 uses a blade with a rounded tip to cut off corners of a workpiece, for example.

[0024] In addition to the end mill 100 and the ball end mill 102, rotary tools such as drills and milling cutters may also be used in machining centers.

[0025] Before actually using a numerical control program to perform machining on an NC machine tool, a mock test (simulation) is sometimes performed on a simulator to verify the numerical control program. The simulator sets up a virtual space as data and places models such as a workpiece model and cutting tool model. The simulator then moves the models in a way that mimics the operations that the numerical control program will cause the NC machine tool to perform, and displays the machining state.

[0026] Therefore, the simulator has a virtual data storage unit that stores data of a virtual space including a workpiece model and a cutting tool model, and a machining control unit that controls simulated machining by gradually moving the workpiece model and the cutting tool model based on a numerical control program and removing the interference area between the workpiece model and the cutting tool model.

[0027] FIG. 2(A) is an image diagram of a virtual space in which an end mill model 110 undergoing machining is viewed from diagonally above. The end mill model 110 is a three-dimensional model of the end mill 100. The end mill model 110 depicts the outer periphery of the end mill 100 as it rotates. In practice, a simple cylindrical model is often used. The end mill model 110 is provided by, for example, a tool manufacturer.

[0028] The holder model 210 is a three-dimensional model of the holder 200. The workpiece model 310 is a three-dimensional model of the workpiece. The end mill model 110 and the holder model 210 move and tilt (rotate) in accordance with the movement of the spindle, but do not deform. The workpiece model 310 moves and tilts (rotates) in accordance with the movement of the table on which the workpiece is placed, and is deformed by machining. Although not shown, a model of the spindle and a model of the table may be included in the virtual space.

[0029] The simulator moves the spindle and table in stages according to a numerical control program. The end mill model 110 and holder model 210 change position and orientation in response to the stepwise movement of the spindle. The workpiece model 310 changes position and orientation in response to the stepwise movement of the table. If the end mill model 110 interferes with the workpiece model 310, the interfering part is removed from the workpiece model 310, causing the workpiece model 310 to deform.

[0030] The end mill 100 is used to cut the outer surface of a workpiece and to machine grooves inside the workpiece. Figure 2(A) shows the groove machining process. The end mill model 110 is placed in the recess 312 and moved in directions perpendicular to the central axis (in the Xm-axis and Ym-axis directions in the figure), thereby expanding the range of the recess 312.

[0031] A position in space within a machine tool is specified by machine coordinates (Xm, Ym, Zm). The machine coordinate system is a coordinate system that specifies a position based on the position and orientation within the machine tool. The machine tool operates based on the machine coordinates. The position of the origin of the machine coordinate system is assumed to be predetermined.

[0032] FIG. 2(B) is an image diagram of a virtual space in which the end mill model 110 is viewed obliquely from below. Although the end mill 100 has a bottom cutting edge on the front, it is not suitable for cutting by pushing it in the direction of the central axis (negative direction of Zm) like a drill (longitudinal feed machining). Therefore, if the end mill model 110 moves in the direction of the central axis in response to a command from the numerical control program and bites into the workpiece model 310, causing interference, this means that the end mill 100 is being used incorrectly.

[0033] In the present invention, a contact warning region 500 is set in front of the end mill model 110. If the contact warning region 500 interferes with the workpiece model 310, there is a possibility that the end mill 100 is being used incorrectly. The contact warning region 500 is an area that requires care to avoid interference with the workpiece model 310, and serves as a "barrier" that stops the progress of cutting. In particular, if the end mill model 110 is moving in the direction of the central axis, there is a high possibility of an error in the numerical control program.

[0034] When the user sets the contact warning region 500, the user operates an operation screen that displays the image of Fig. 2(B) to specify the range of the contact warning region 500. However, since the contact warning region 500 in Fig. 2(B) is uniquely determined by the shape of the end mill model 110, it is not necessary to reset the contact warning region 500 every time the end mill model 110 is used.

[0035] Even if the contact warning area 500 interferes with the workpiece model 310, if the end mill model 110 is moving perpendicular to the central axis, for example, in groove machining, the side blade is cutting the workpiece normally, so it is considered that the usage is correct.

[0036] Here is another example of incorrect use of the end mill 100. For example, when machining a groove, if the groove is too deep, the cutting surface becomes large and the cutting resistance increases. If the cutting resistance is high, excessive force is applied to the blade of the end mill 100, which can reduce the surface quality or cause the tool to break. Therefore, it is possible to limit the depth at which the tip of the cutter 104 of the end mill 100 comes into contact with the workpiece.

[0037] FIG. 3A is a diagram showing a contact warning region set on the side surface of the end mill model 110. As shown in FIG. As shown in the figure, the area other than the tip of the cutter 104 with a predetermined length is set as a contact warning area 500. If the groove is too deep, the contact warning area 500 will interfere with the workpiece, and it can be determined that the end mill 100 is being used incorrectly.

[0038] FIG. 3B is a diagram showing the operation screen. A method for setting the contact warning region 500 in FIG. 3(A) on this operation screen will be described. An image of the end mill model 110 viewed from the side (perpendicular to the central axis) is displayed on the operation screen. The user operates the mouse to input the specified range 502 shown in the figure. The specified range 502 is expressed as a frame on a vertical plane and is specified as a two-dimensional range. The simulator sets the part of the end mill model 110 inside the specified range 502 (including the back side that is not visible from the screen) as the contact warning region 500.

[0039] FIG. 4(A) is an image diagram of a virtual space of the ball end mill model 112 during machining. The ball end mill model 112 is a three-dimensional model of the ball end mill 102. The ball end mill model 112 moves and tilts in accordance with the operation of the spindle, but does not deform.

[0040] In the simulator, the ball end mill model 112 and holder model 210 change position and orientation in response to the stepwise movement of the spindle. If the ball end mill model 112 interferes with the workpiece model 310, the interfering portion is removed from the workpiece model 310, and the workpiece model 310 is deformed into the machined shape.

[0041] The ball end mill 102 is used to remove the corners of a workpiece, for example. Figure 4(A) shows how the corner of a protrusion 314 on the workpiece is removed. The tip of the ball end mill 102 is brought into contact with the corner to remove the corner. However, the central part of the approximately hemispherical tip, where the center line passes (the point where the central axis passes), simply twists, and the orbit of the cutting edge does not trace a circle. In other words, this is a point where the peripheral speed is zero. The peripheral speed near this point is low and not suitable for cutting. In other words, bringing the center part of the tip of the ball end mill 102 into contact with the workpiece is an incorrect way to use the ball end mill.

[0042] FIG. 4(B) is an image diagram of a virtual space in which the ball end mill model 112 is viewed obliquely from below. In the present invention, a contact warning region 500 is set near the center of the tip of the ball end mill model 112. If the contact warning region 500 interferes with the workpiece model 310, there is a possibility that the ball end mill 102 is being used incorrectly.

[0043] When the user sets the contact warning region 500, the user operates an operation screen that displays the image of Fig. 4(B) to specify the range of the contact warning region 500. However, since the contact warning region 500 in Fig. 4(B) is determined substantially by the shape of the ball end mill model 112, it is not necessary to reset the contact warning region 500 every time the ball end mill model 112 is used.

[0044] FIG. 5 is a functional block diagram of the simulator 400. The components of the simulator 400 are implemented by hardware including computing units such as a CPU and various coprocessors, storage devices such as memory and storage, and wired or wireless communication lines connecting them, as well as software stored in the storage devices and supplying processing instructions to the computing units. The computer program may be configured by device drivers, an operating system, various application programs located at higher levels, and libraries that provide common functions to these programs. Each block shown in the figure represents a functional block, not a hardware configuration. This is true for both a desktop simulator 400 and a simulator 400 on a real machine.

[0045] The simulator 400 includes a user interface processing unit 410, a data storage unit 440, and a data processing unit 480. The user interface processing unit 410 is responsible for user interface processing via the simulator 400's display, keyboard, mouse, touch sensor, and touch panel integrating a display and touch sensor. The data storage unit 440 stores various data. The data storage unit 440 is realized, for example, by RAM, ROM, flash memory, SSD (Solid State Drive), hard disk, or other storage device, or an appropriate combination thereof. The data processing unit 480 performs various processes based on data input by the user interface processing unit 410 and data stored in the data storage unit 440. The data processing unit 480 also functions as an interface between the user interface processing unit 410 and the data storage unit 440.

[0046] The user interface processing unit 410 includes an input unit 420 for inputting data through user operations, and an output unit 430 for outputting data to be provided to the user. The input unit 420 includes an operation receiving unit 422 that receives data input by events detected by input devices such as a keyboard, a mouse, a touch sensor, a touch panel, etc. The output unit 430 includes a display processing unit 432 that displays various screens on a display device such as a display or a touch panel.

[0047] The data processing unit 480 includes a setting unit 482 , a processing control unit 484 , a detection unit 486 , and a notification unit 488 . The setting unit 482 sets data such as the collision warning area 500 and the response to interference ("interrupt" or "continue"). The machining control unit 484 controls the simulated machining by moving the model stepwise in accordance with commands from the numerical control program. The detection unit 486 detects interference in the workpiece model 310 and determines whether or not caution is required. The notification unit 488 issues various notifications to the user.

[0048] The data storage unit 440 includes a numerical control program storage unit 442 , a virtual space data storage unit 444 , and a detection result storage unit 446 . The numerical control program storage unit 442 stores a numerical control program. The virtual space data storage unit 444 stores virtual space data (including various three-dimensional models). The detection result storage unit 446 stores the detection results by the detection unit 486.

[0049] 6 and 7 show the processing flow of the simulator 400. The display processing unit 432 displays a menu (not shown) on the display device, and the operation receiving unit 422 starts receiving user operations (S10).

[0050] When the user selects the item "Set Contact Caution Area" included in the menu, an operation screen such as that shown in FIG. 3(B) is displayed. When the user inputs a specified range 502, the setting unit 482 sets a contact caution area 500 in the area inside the specified range 502 (including the back side that is not visible from the screen) (S12). The contact caution area 500 is added to the end mill model 110. Furthermore, the external view of FIG. 2(B) may be displayed to set the contact caution area 500, or the external view of FIG. 4(B) may be displayed to set the contact caution area 500. The shape of the specified range 502 may be other than rectangular, such as a circle.

[0051] In the present invention, the user can determine in advance how to respond when the contact warning region 500 and the workpiece model 310 collide. When the user determines how to respond to interference, the user selects the "Interference Response Settings" item included in the menu. The user can set either "Interrupt," which temporarily stops the simulated machining midway, or "Continue," which continues the simulated machining without stopping. The setting unit 482 stores the interference response set by the user in the data storage unit 440 (S14).

[0052] When the user selects the item "Start Simulation" included in the menu, the machining control unit 484 starts a simulation of the cutting process (S16).

[0053] The machining control unit 484 moves the model stepwise in accordance with commands from the numerical control program (S18). The model moves at predetermined time intervals. The display processing unit 432 displays an image of the model projected in the virtual space on a display device. For example, if the model is moved at 0.04 second intervals, a moving image equivalent to a general animation can be displayed.

[0054] The targets of the operation are models included in the virtual space data, such as the end mill model 110, the ball end mill model 112, the holder model 210, and the workpiece model 310. The contact warning region 500 also moves together with the tool model as part of the tool model, such as the end mill model 110 or the ball end mill model 112. The movement may involve not only moving the position of the model but also tilting the model.

[0055] The detection unit 486 determines whether or not the holder model 210 interferes with the workpiece model 310 due to the stepwise movement of the model (S20). Essentially, the holder 200 must not come into contact with the workpiece, as this could damage the holder 200 or the workpiece, or distort the spindle.

[0056] If the holder model 210 interferes with the workpiece model 310 (Y in S20), this is an obvious error, so the machining control unit 484 suspends the simulation (S22) and prompts the user for confirmation.

[0057] The user checks the state of the model on the screen and identifies any problems with the numerical control program. If there is no need to continue the simulation any further, the user instructs the simulation to end without restarting it (N in S24). In this case, the machining control unit 484 ends the simulation at that point (S28).

[0058] If the user wishes to check subsequent operations, he or she instructs the simulation to be restarted. When the operation receiving unit 422 receives an instruction to restart the simulation (Y in S24), the machining control unit 484 determines whether or not the end of the numerical control program has been processed (S26). If the end has not yet been reached (N in S26), the process returns to S18 and the above-mentioned processing is repeated. If the end has been reached (Y in S26), the machining control unit 484 ends the simulation (S28).

[0059] Returning to the explanation of S20, if the stepwise movement of the models does not cause interference between the holder model 210 and the workpiece model 310 (N in S20), the process proceeds to the processing of FIG.

[0060] The detection unit 486 determines whether or not the collision warning region 500 has interfered with the workpiece model 310 due to the stepwise movement of the model (S40). If it is determined that the collision warning region 500 has not interfered with the workpiece model 310 (N in S40), the process proceeds to S26 via terminal C.

[0061] If it is determined that the collision warning region 500 has interfered with the workpiece model 310 (Y in S40), the detection unit 486 stores the detection result regarding the interference in the detection result storage unit 446 (S42).

[0062] If the contact warning area 500 (FIG. 4(B)) of the ball end mill model 112 causes interference, it is judged as "Caution Required" regardless of the moving direction of the ball end mill model 112. If the contact warning area 500 (FIG. 2(B)) on the front side of the end mill model 110 causes interference, the moving direction of the end mill model 110 is also judged. If the end mill model 110 is moving in the direction of the central axis (in the case of vertical feed machining), it is judged as "Caution Required," and if the end mill model 110 is moving in a direction perpendicular to the central axis (in the case of lateral feed machining), it is judged as "No Caution Required." As described above, vertical feed machining of the end mill 100 is an incorrect use, and lateral feed machining is the correct way to use it.

[0063] The detection results include the command that caused the interference, the time from the start of processing until the interference occurred, an image (snapshot) of the virtual space in the interference state, and three-dimensional data of the virtual space (including the position and angle of each model). It is sufficient to record the detection results only for interference that is determined to be "attention required."

[0064] The image of the virtual space and the three-dimensional data of the virtual space may be distinguished by color, pattern, or framing to indicate the interference range in the workpiece model 310. By the display processing unit 432 displaying the interference range in the workpiece model 310 in a visually distinguishable manner, the user can easily check and understand the situation when reviewing it later. For example, if there is a problem with the finish of a surface as a result of actual machining using an NC machine tool, the user can compare the problematic surface with the interference range to determine whether the interference affected the finish.

[0065] At this time, the notification unit 488 may notify the user of the detection result. Specifically, for example, the display processing unit 432 causes the display device to display the detection result.

[0066] The machining control unit 484 determines whether the set action to be taken when interference occurs is "interrupt" or "continue" (S44). If the action to be taken when interference occurs is "continue" (N at S44), the process proceeds to processing of S26 via terminal C to continue the simulation. If the action to be taken when interference occurs is "interrupt" (Y at S44), the process proceeds to processing of S22 via terminal B to interrupt the simulation.

[0067] The above-described processes from S18 to S26 are repeated until the end of the numerical control program is reached, and when the end is reached (Y in S26), the machining control unit 484 ends the simulation (S28).

[0068] Finally, the notification unit 488 notifies the user of the detection result stored in the detection result storage unit 446 (S30). Specifically, for example, the display processing unit 432 causes the display device to display the detection result.

[0069] An example of a notification common to the desktop simulator 400 and the actual simulator 400 is a message output such as "The contact warning area and the workpiece have collided. (xxx part of the numerical control program)."

[0070] Examples of notifications from the desktop simulator 400 include messages such as "The accuracy of the machined surface may be decreasing," "Increase the tool rotation speed (narrow the area where the peripheral speed is low)," or "Decrease the tool feed rate (reduce the cutting load)."

[0071] As an example of a notification from the simulator 400 on the actual machine, messages such as "Check the tool wear" or "The tool may be heavily worn. This will be reflected in the tool life" may be output.

[0072] As described above, the detection unit 486 detects that the contact warning area 500 set on a part of the surface of the end mill model 110 or the ball end mill model 112 has interfered with the workpiece model 310, making it easier to predict interference between the end mill 100 and the workpiece or between the ball end mill 102 and the workpiece, which can be a problem in actual machining.

[0073] [Variation 1] Although FIG. 3B shows an example in which the specified range 502 is specified as a two-dimensional range, the specified range 502 may be specified as a three-dimensional range.

[0074] FIG. 8 is a diagram showing an operation screen in the first modification. An image of the holder model 210 and the end mill model 110 viewed from diagonally above is displayed on the operation screen. The user operates a mouse, for example, to input a specified range 502 as shown in the figure. The specified range 502 is expressed as a cylindrical shape and is specified as a three-dimensional range. The setting unit 482 sets the part of the end mill model 110 inside the specified range 502 (including the back side that is not visible from the screen) as a contact warning region 500.

[0075] [Variation 2] FIG. 9 is a diagram showing an operation screen in the second modification. The specified range 502 may be specified numerically. BR in the figure means the length of the specified range 502 from the holder. In this example, BR is specified as "46.000", so the length in the central axis direction of the specified range 502 is 46 mm. The length from the tip may also be specified as a percentage (%) of the total length.

[0076] 4B, the size of the contact caution region 500 provided on the ball end mill model 112 may be specified by the diameter. Alternatively, the contact caution region 500 may be specified by the central angle of the approximate hemisphere at the tip of the ball end mill model 112.

[0077] [Variation 3] In the embodiment, examples of the end mill 100 and the ball end mill 102 are shown, but the present invention may also be applied to a face mill (milling tool).

[0078] FIG. 10A is a perspective view of the face mill 120. FIG. As shown in the figure, a cutter 122 is attached to the corner where the front and side of the face mill 120 intersect. When the spindle rotates, the holder 200 and face mill 120 rotate as a unit. The cutter 122 cuts the workpiece as it rotates. A portion of the holder 200 protrudes through the center 124 of the front of the face mill 120. Cutting is not possible in this area.

[0079] FIG. 10(B) is an image diagram of a virtual space in which the face mill model 130 is viewed obliquely from below. In a simple face mill model 130 representing a rotating body, the front center portion 124 is included in the face mill model 130. Therefore, in the simulation, the portion of the workpiece that interferes with the front center portion 124 is removed. However, this is an incorrect usage because it is not possible to actually cut it. Therefore, it is advisable to set a contact warning region 500 at the front center portion 124, detect cases where the front center portion 124 comes into contact with the workpiece, and issue a warning.

[0080] [Variation 4] The present invention may also be applied to a drill. In the case of a drill, it is conceivable to provide a contact warning region 500 on the side. A drill is intended to be moved in the direction of its central axis to drill a hole. Therefore, if the contact warning region 500 interferes with the workpiece model 310 and the drill model is moving perpendicular to the central axis, it is considered that the drill is being used incorrectly.

[0081] [Variation 5] In the above example, a machining center that performs turning has been shown, but the NC machine tool to which the present invention is applied may also be a turning center or NC lathe that performs turning. A tool used for turning is called a "turning tool." Note that both the rotating tool described above and the turning tool described below are cutting tools. The turning tool described below is an example of a turning tool.

[0082] FIG. 11A is a perspective view of the cutting tool 140. FIG. The tool bit 140 has a tip 144 and a shank 142. The tip 144 is fixed with a screw 146. The shank 142 is attached to an NC machine tool, and the tool bit 140 is fixed so as not to rotate. Turning is performed by bringing the sharp cutting edge of the tip 144 into contact with a rotating workpiece.

[0083] FIG. 11B is a diagram showing an operation screen in the fifth modification. The tool bit model 150 is a three-dimensional model of the tool bit 140 in virtual space. The tip model 154 is a three-dimensional model of the tip 144 in virtual space. The tip model 154 included in the tool bit model 150 is displayed on the operation screen. The user operates a mouse, for example, to input the illustrated exclusion range 504. The exclusion range 504 is an area that is not to be set as the contact warning area 500. In this example, the exclusion range 504 is set on the cutting edge used for turning. The shape of the exclusion range 504 may be other than a circle, for example, a rectangle.

[0084] FIG. 11C is a diagram showing a contact warning area 500 of the tool bite model 150. The part of the tip model 154 outside the exclusion range 504 becomes the contact warning area 500. Therefore, it is determined whether any part other than the cutting edge is in contact with the workpiece. Normally, the cutting edge is used, but exceptionally, a part of the blade other than the cutting edge (hereinafter referred to as the "root side") may be used. For example, the root side may be used when forming soft jaws or performing some rough machining. However, when the root side is used, the cutting load is high, so the material gripping pressure, material rotation speed, and tool feed speed are adjusted to match the high cutting load. Specifically, the material gripping pressure is increased, the material rotation speed is decreased, and the tool feed speed is decreased.

[0085] If these adjustments are not made, the root side may come into contact with the workpiece, which can lead to problems such as a decrease in surface quality or the workpiece falling off. Considering this point, detecting interference in the contact warning area 500 is convenient because it makes it easier to find cases where the root side is being used by mistake or where the root side is being used intentionally but the necessary adjustments have not been made.

[0086] A contact attention region 500 may be set for the tip model 154 instead of setting the exclusion range 504. For example, the contact attention region 500 may be set on the back side of the blade of the tip model 154 so that the back side of the blade of the tip 144 is not used.

[0087] [Variation 6] For example, if the contact attention region 500 (FIG. 4(B)) of the ball end mill model 112 causes interference, one possible measure is to increase the tool rotation speed to narrow the region where the peripheral speed is low. Also, if the contact attention region 500 (FIG. 3(A)) on the side of the end mill model 110 causes interference, one possible measure is to reduce the tool feed rate to reduce the cutting load. The notification unit 488 may notify the user of these measures and provide advice. To implement these measures, the numerical control program may be modified, or an override function of the NC machine tool in operation may be used.

[0088] The contents of the advice are stored in the data storage unit 440 in association with the type of tool model and the part (front, side, etc.) of the contact warning area 500. The notification unit 488 can identify the contents of the advice based on the type of tool model that has caused the collision and the part of the contact warning area 500.

[0089] [Variation 7] The on-machine simulator 400 may be linked to a tool measurement device. For interference determined to be "attention required" in S40, the setting unit 482 may measure tool wear in detail using the tool measurement device and reflect the results in the tool life data stored in the data storage unit 440.

[0090] [others] To correct a numerical control program, the user typically re-operates the CAD and CAM and re-posts the results. To assist in this process, the simulator 400 may be provided with a correction unit (not shown) that proposes corrections to the numerical control program. When the user instructs application of the proposed corrections to the numerical control program, the correction unit may apply the proposed corrections to the numerical control program in the numerical control program storage unit 442.

[0091] Finally, the method for setting the contact warning area 500 will be summarized. Graphically set on the 3D model surface (Fig. 2(B), Fig. 4(B)). Set it as a two-dimensional shape (such as a rectangle) (Figure 3(B)). Set it in a three-dimensional geometric area (such as a cylinder) (Figure 8). Set it parametrically (Figure 9). An area outside the contact warning area 500 is selected and set (FIG. 11(B)).

[0092] [summary] As described above, the detection unit 486 detects that the contact warning area 500 set on a part of the surface of the tool model (end mill model 110, ball end mill model 112, face mill model 130, and bit model 150) has interfered with the workpiece model 310, making it easier to predict interference between the tool and the workpiece that will cause problems during actual machining.

[0093] Furthermore, since the setting unit 482 sets the contact attention region 500 based on the exclusion range 504 that is not set as the contact attention region 500, it becomes easier to set a region for finding contact other than at a location that is intentionally used (for example, the cutting edge).

[0094] Furthermore, the detection unit 486 determines whether caution is required or not depending on the traveling direction of the tool model, which makes it easier to detect incorrect usage of the tool other than the correct usage.

[0095] Furthermore, since the setting unit 482 reflects tool wear in the tool life data, it becomes easier to grasp the deterioration state of the tool due to improper use.

[0096] Furthermore, since the display processing unit 432 displays the range of interference with the contact warning region 500 in a visually distinguishable manner, the user can easily grasp the interference situation with the contact warning region 500.

[0097] Furthermore, the notification unit 488 advises the user on how to deal with interference with the contact warning area 500, making it easier for the user to take action.

[0098] The present invention is not limited to the above-described embodiments and modifications, and the components can be modified without departing from the spirit of the invention. Various inventions can be formed by appropriately combining multiple components disclosed in the above-described embodiments and modifications. Furthermore, some components can be omitted from all the components shown in the above-described embodiments and modifications. [Explanation of symbols]

[0099] 100 end mill, 102 ball end mill, 104 cutter, 106 shank, 110 end mill model, 112 ball end mill model, 120 face mill, 122 cutter, 124 front center portion, 130 face mill model, 140 bit, 142 shank, 144 tip, 146 screw, 150 bit model, 154 tip model, 200 holder, 210 holder model, 310 workpiece model, 312 concave portion, 314 convex portion, 400 simulator, 410 user interface processing unit, 420 input unit, 422 operation reception unit, 430 output unit, 432 display processing unit, 440 data storage unit, 442 numerical control program storage unit, 444 virtual space data storage unit, 446 detection result storage unit, 480 data processing unit, 482 setting unit, 484 Machining control unit, 486 detection unit, 488 notification unit, 500 contact warning area, 502 specified range, 504 exclusion range

Claims

1. A simulator that simulates machining of a workpiece by a tool used in a machine tool that operates based on a numerical control program, a virtual data storage unit that stores data of a virtual space including a workpiece model and a tool model; a setting unit that sets a contact warning region on a part of a surface of the tool model; a machining control unit that controls simulated machining by moving the workpiece model and the tool model in stages based on the numerical control program to remove an interference area between the workpiece model and the tool model; a detection unit that detects interference between the contact attention region and the workpiece model during stepwise movement in the machining control unit, A simulator characterized in that, when the contact warning area interferes with the work model, the detection unit determines whether caution is required or not based on the direction of travel of the tool model.

2. The simulator according to claim 1 , wherein the setting unit reflects the wear of the tool determined to require attention in data on the tool life.

3. A computer that performs a simulation using virtual space data including a workpiece model and a tool model for machining a workpiece with a tool used in a machine tool that operates based on a numerical control program. a setting function for setting a contact warning region on a part of a surface of the tool model; a machining control function that controls simulated machining by moving the workpiece model and the tool model in stages based on the numerical control program to remove an interference area between the workpiece model and the tool model; a detection function for detecting interference between the contact attention region and the workpiece model during stepwise movement in the machining control function; A simulation program characterized in that, in the detection function, when the contact attention area interferes with the work model, it is determined whether caution is required or not based on the direction of travel of the tool model.

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