Vibration cutting condition setting device for machine tools

Abstract

To provide a vibration cutting condition setting device which facilitates selection of a tool for vibration cutting and setting of a parameter.SOLUTION: A vibration cutting condition setting device 3 for a machine tool 1 includes: a display section U3; and a control section U4. The control section U4 receives feed speed (F) when a drive object is not vibrated, a first parameter (A) related to a period of vibration, and a second parameter (E) related to amplitude of vibration as setting for controlling feed movement of the drive object so as to accompany vibration. The control section U4 determines maximum feed speed (Fmax) of the drive object on the basis of the feed speed (F) when the drive object is not vibrated, the first parameter (A), and the second parameter (E), and displays a value showing the determined maximum feed speed (Fmax) on the display section U3.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a vibration cutting condition setting device for a machine tool that cuts a workpiece held by a spindle with a tool. [Background technology]

[0002] Numerically controlled (NC) automatic lathes, equipped with a spindle that grips the workpiece, are well known machine tools. When chips generated by the workpiece rotating with the spindle become long, they can wrap around the cutting tool, potentially affecting the continuous machining of the workpiece. To address this issue, vibration cutting is used, in which the tool is fed alternately between forward movement toward the workpiece and backward movement away from the workpiece, thereby breaking up the chips. Chips are also called swarf. The degree to which chips break down varies depending on the spindle phase, vibration amplitude, feed rate during forward movement, and feed rate during backward movement. Operators set these parameters in the NC automatic lathe to allow the NC automatic lathe to perform vibration cutting.

[0003] The machining system disclosed in Patent Document 1 generates first waveform data representing changes in position information over time from time-series position information of the feed axis at regular time intervals, divides the first waveform data into partial waveform data for each time period per rotation of the spindle, and sequentially shifts each partial waveform data along the time axis to align it with the start point of the first waveform data, thereby generating and displaying multiple second waveform data. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-195002 Summary of the Invention [Problem to be solved by the invention]

[0005] Cutting tools have upper limits on feed speed and other cutting conditions set as recommended cutting conditions to prevent chipping, welding, etc. Here, one possible method of feed control during vibration cutting is to control the feed movement of the tool so that it vibrates based on the feed speed when the tool is not vibrating, a period parameter related to the period of vibration, and an amplitude parameter related to the amplitude of vibration. In this case, since the operator does not know the maximum feed speed during forward movement, he or she cannot properly select a tool and cannot properly set parameters for vibration cutting. The above-mentioned problems are not limited to lathes, but also exist in various machine tools such as machining centers.

[0006] The present invention discloses a vibration cutting condition setting device that makes it easy to select a tool for vibration cutting and set parameters. [Means for solving the problem]

[0007] The vibration cutting condition setting device for a machine tool of the present invention includes a rotation drive unit that rotates a spindle that grips a workpiece, and a feed drive unit that moves at least one of a tool that cuts the workpiece and the spindle, and when cutting the workpiece, The tool moves relative to the workpiece. The tool moves along the cutting direction. Relatively 1. A vibration cutting condition setting device for a machine tool that controls feed movement of a driven object so as to accompany vibration including a forward movement toward the workpiece and a backward movement in a direction opposite to the forward movement, A display unit; a control unit that receives a feed speed (F) of the driven object when it is not vibrating, a first parameter (A) related to a period of the vibration, and a second parameter (E) related to an amplitude of the vibration as settings for controlling the feed movement of the driven object so as to accompany the vibration; The control unit a phase of the main shaft at a first change point where the forward motion changes to the backward motion in one cycle of the vibration and a phase of the main shaft at a second change point where the backward motion changes to the forward motion in one cycle of the vibration are matched, determining a maximum feed speed (Fmax) of the driven object based on the non-vibration feed speed (F) of the driven object, the first parameter (A), and the second parameter (E); The value representing the maximum feed rate (Fmax) is displayed on the display unit. death, Accepting an operation to change the maximum feed rate (Fmax) displayed on the display unit; calculating a cutting time (CT) required for the feed movement of the driven object accompanied by the vibration at the changed maximum feed rate (Fmax) based on the changed maximum feed rate (Fmax), the first parameter (A), and the second parameter (E); The value representing the cutting time (CT) thus obtained is displayed on the display unit. It has an aspect of: Furthermore, the vibration cutting condition setting device for a machine tool of the present invention is a vibration cutting condition setting device for a machine tool that includes a rotation drive unit that rotates a spindle that grips a workpiece, and a feed drive unit that moves at least one of a tool that cuts the workpiece and a drive object of the spindle, and that controls the feed movement of the drive object so as to accompany vibrations including a forward movement of the tool relatively toward the workpiece and a backward movement in the opposite direction to the forward movement along a cutting direction in which the tool moves relatively with respect to the workpiece when cutting the workpiece, A display unit; a control unit that receives a feed speed (F) of the driven object when it is not vibrating, a first parameter (A) related to a period of the vibration, and a second parameter (E) related to an amplitude of the vibration as settings for controlling the feed movement of the driven object so as to accompany the vibration; The control unit determining a maximum feed rate (Fmax) of the driven object based on a feed rate (F) of the driven object when it is not vibrating, the first parameter (A), and the second parameter (E) under a condition that a phase of the main spindle at a first change point where the forward motion changes to the backward motion in one cycle of the vibration coincides with a phase of the main spindle at a second change point where the backward motion changes to the forward motion in one cycle of the vibration; The value representing the determined maximum feed rate (Fmax) is displayed on the display unit; Accepting an operation to change the maximum feed rate (Fmax) displayed on the display unit; changing a feed rate (F) of the driven object when the driven object is not vibrating based on the changed maximum feed rate (Fmax), the first parameter (A), and the second parameter (E); The display unit may display a value representing the changed feed speed (F) of the driven object when it is not vibrating. [Effects of the Invention]

[0008] According to the present invention, it is possible to easily select a tool for vibration cutting and set parameters. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram schematically illustrating an example of the configuration of a machine tool. [Figure 2] FIG. 2 is a block diagram schematically illustrating an example of the configuration of an electric circuit of a machine tool. [Figure 3] 10 is a diagram schematically showing an example of a tool position relative to a spindle rotation angle when the chip length coefficient A1 is 2. FIG. [Figure 4] FIG. 10 is a diagram schematically showing an example of the tool position relative to the spindle phase when the chip length coefficient A1 is 2. [Figure 5] FIG. 10 is a diagram schematically showing an example of the tool position relative to the spindle rotation angle when the chip length coefficient A1 is 3. [Figure 6] 10A and 10B are diagrams illustrating an example of controlling the position of a tool during feed movement based on a vibration feed command. [Figure 7] FIG. 10 is a diagram schematically showing an example of the tool position relative to the spindle rotation angle when the chip length coefficient A1 is 2 / 3. [Figure 8] FIG. 10 is a diagram schematically showing an example of the tool position relative to the spindle phase when the chip length coefficient A1 is 2 / 3. [Figure 9] FIG. 10 is a diagram schematically illustrating an example of a setting screen for a vibration feed command CM1. [Figure 10] FIG. 2 is a diagram schematically illustrating an example of the structure of an information table. [Figure 11] FIG. 10 is a diagram schematically showing an example of accepting a change in the maximum feed speed Fmax. [Figure 12] FIG. 10 is a diagram schematically illustrating an example of a setting screen for a vibration feed command CM2. [Figure 13] FIG. 10 is a diagram schematically showing another example of a tool position relative to a spindle rotation angle. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following describes embodiments of the present invention. Of course, the following embodiments are merely examples of the present invention, and not all of the features shown in the embodiments are necessarily essential to the solution of the invention.

[0011] (1) Overview of the technology included in this invention: First, an overview of the technology included in the present invention will be described with reference to the examples shown in Figures 1 to 13. Note that the figures in this application are diagrams showing schematic examples, and the magnifications in the directions shown in these figures may differ, and the figures may not be consistent. Of course, each element of the present technology is not limited to the specific example indicated by the symbol.

[0012] [Aspect 1] 1 and 2, a machine tool 1 according to one aspect of the present technology includes a rotation drive unit U1 that rotates a spindle 11 that grips a workpiece W1, and a feed drive unit U2 that moves a tool TO1 that cuts the workpiece W1 and at least one of the driven objects (e.g., tool TO1) of the spindle 11. The machine tool 1 controls the feed movement of the driven object so that, when cutting the workpiece W1, the tool TO1 is accompanied by vibrations including a forward movement M1 in which the tool TO1 moves toward the workpiece W1 along a cutting direction (e.g., a feed axis F1) and a backward movement M2 in the opposite direction to the forward movement M1. The vibration cutting condition setting device 3 for the machine tool 1 includes a display unit U3 and a control unit U4. The control unit U4 receives a feed rate (F) of the driven object when the driven object is not vibrating, a first parameter (A) related to the period of the vibration, and a second parameter (E) related to the amplitude of the vibration as settings for controlling the feed movement of the driven object to accompany the vibration. The control unit U4 determines a maximum feed rate (Fmax) of the driven object based on the feed rate (F) of the driven object when the driven object is not vibrating, the first parameter (A), and the second parameter (E), and displays a value representing the determined maximum feed rate (Fmax) on the display unit U3.

[0013] As described above, since a value representing the maximum feed rate (Fmax), which is unknown in the accepted settings, is displayed, the operator can easily select a tool TO1 for vibration cutting by looking at the value representing the maximum feed rate (Fmax), and can easily set parameters for vibration cutting. Therefore, the above-mentioned aspect 1 can provide a vibration cutting condition setting device that makes it easy to select a tool for vibration cutting and set parameters.

[0014] Here, machine tools include lathes, machining centers, etc. The feed drive unit may move the tool along the cutting direction without moving the workpiece, may move the workpiece along the cutting direction without moving the tool, or may move both the tool and the workpiece along the cutting direction. The first parameter (A) relating to the vibration period may be any parameter related to the period, and is not limited to the period itself. The first parameter (A) includes the chip length coefficient A1, the period A2, etc. The second parameter (E) relating to the amplitude of vibration may be any parameter related to the amplitude, and is not limited to the amplitude itself. The second parameter (E) includes the amount of retraction E1, the amplitude E2, and the like. The value representing the maximum feed rate is not limited to a value in mm / rev, but may be a conversion value such as the ratio of the maximum feed rate to the normal cutting feed rate, or the difference between the normal cutting feed rate and the maximum feed rate. The above remarks also apply to the following aspects.

[0015] [Aspect 2] 11, the control unit U4 may accept an operation to change the maximum feed rate (Fmax) displayed on the display unit U3. The control unit U4 may change the feed rate (F) of the driven object when it is not vibrating based on the changed maximum feed rate (Fmax), the first parameter (A), and the second parameter (E), and may display a value representing the changed feed rate (F) of the driven object when it is not vibrating on the display unit U3. This embodiment makes it possible to change the maximum feed rate (Fmax) to suit a cutting tool or the like, and also makes it possible to confirm the changed feed rate (F) of the driven object when it is not vibrating, making it easy to set the feed rate (F) of the driven object when it is not vibrating. Here, the value representing the feed speed of the driven object when it is not vibrating is not limited to a value in mm / rev, but may be a converted value such as the ratio of the feed speed of the driven object when it is not vibrating after the change to the feed speed of the driven object when it is not vibrating before the change, or the difference between the feed speed of the driven object when it is not vibrating before the change and the feed speed of the driven object when it is not vibrating after the change. This remark also applies to the following aspects.

[0016] [Aspect 3] 11, the control unit U4 may calculate a cutting time (CT) required for the feed movement of the driven object accompanied by the vibration at the changed maximum feed rate (Fmax) based on the changed maximum feed rate (Fmax), the first parameter (A), and the second parameter (E), and may display a value representing the calculated cutting time (CT) on the display unit U3. This embodiment makes it possible to change the maximum feed rate (Fmax) in accordance with the cutting tool, etc., and also makes it possible to check the cutting time (CT) at the changed maximum feed rate (Fmax). Here, the value representing the cutting time is not limited to a value in minutes, but may be a converted value such as the ratio of the cutting time after the change to the cutting time before the change, the difference between the cutting time before the change and the cutting time after the change, etc. This remark also applies to the following aspects.

[0017] [Aspect 4] The control unit U4 may accept an operation to change the cutting time (CT) required for the feed movement of the driven object accompanied by vibration. The control unit U4 may change at least one feed rate parameter of the non-vibration feed rate (F) of the driven object and the maximum feed rate (Fmax) based on the changed cutting time (CT), and may display a value representing the changed feed rate parameter on the display unit U3. This aspect makes it easy to set parameters for vibration cutting because it is possible to check the feed rate parameter that changes as the cutting time (CT) is changed.

[0018] (2) Specific examples of machine tool configurations: FIG. 1 shows a schematic diagram of a lathe as an example of a machine tool 1, along with the configuration of an external computer 100. The machine tool 1 shown in FIG. 1 is an NC automatic lathe equipped with an NC (numerical control) device 70 that performs numerical control of the machining of a workpiece W1. Since the computer 100 is not an essential element of the machine tool 1, the computer 100 may not be connected to the machine tool 1. In this example, the machine tool 1 includes a vibration cutting condition setting device 3.

[0019] The machine tool 1 is an NC machine tool equipped with a headstock 10 incorporating a spindle 11 having a gripper 12, a headstock drive unit 14, a tool rest 20, a feed drive unit U2 for the tool rest 20, an NC device 70, and the like. Here, the headstock 10 collectively refers to a front headstock 10A and a back headstock 10B, also called an opposed headstock. The front headstock 10A incorporates a front spindle 11A having a gripper 12A, such as a collet. The back headstock 10B incorporates a back spindle 11B having a gripper 12B, such as a collet. The spindle 11 collectively refers to the front spindle 11A and the back spindle 11B, also called an opposed spindle. The gripper 12 collectively refers to the gripper 12A and the gripper 12B. The headstock drive unit 14 collectively refers to the front headstock drive unit 14A that moves the front headstock 10A and the back headstock drive unit 14B that moves the back headstock 10B. The rotation drive unit U1 for the spindle 11 includes a motor 13A that rotates the front spindle 11A about the spindle center line AX1, and a motor 13B that rotates the back spindle 11B about the spindle center line AX1. Built-in motors incorporated in the spindles can be used as the motors 13A and 13B. Of course, the motors 13A and 13B may also be located outside the spindle 11.

[0020] The control axes of the machine tool 1 shown in FIG. 1 include an X-axis indicated by "X," a Y-axis indicated by "Y," and a Z-axis indicated by "Z." The Z-axis direction is a horizontal direction along the spindle center line AX1, which is the center of rotation of the workpiece W1. The X-axis direction is a horizontal direction perpendicular to the Z-axis. The Y-axis direction is a vertical direction perpendicular to the Z-axis. Note that the Z-axis and the X-axis do not have to be perpendicular as long as they intersect, the Z-axis and the Y-axis do not have to be perpendicular as long as they intersect, and the X-axis and the Y-axis do not have to be perpendicular as long as they intersect. The drawings referenced in this specification merely illustrate examples for explaining the present technology and do not limit the present technology. Furthermore, the positional relationships of each part are merely illustrative. Therefore, reversing the left and right sides, reversing the direction of rotation, etc., are also included in the present technology. Furthermore, the term "identity of direction, position, etc." does not necessarily mean strict agreement, but also includes deviations from strict agreement due to errors.

[0021] 1 is a moving spindle type lathe, in which a front headstock drive unit 14A moves a front headstock 10A in the Z-axis direction, and a back headstock drive unit 14B moves a back headstock 10B in the Z-axis direction. Of course, the machine tool 1 may be a fixed spindle type lathe in which the front headstock 10A does not move, or in which the front headstock 10A moves in the Z-axis direction without moving the back headstock 10B.

[0022] The front spindle 11A releasably grips the workpiece W1 with the gripping portion 12A and is rotatable together with the workpiece W1 around the spindle center line AX1. If the workpiece W1 before machining is, for example, a long, cylindrical (rod-shaped) material, the workpiece W1 may be supplied to the gripping portion 12A from the rear end (left end in FIG. 1) of the front spindle 11A. In this case, a guide bush that supports the workpiece W1 so that it can slide in the Z-axis direction may be disposed on the front side (right side in FIG. 1) of the front spindle 11A. If the workpiece W1 before machining is a short material, the workpiece W1 may be supplied to the gripping portion 12A from the front end of the front spindle 11A. The motor 13A rotates the front spindle 11A together with the workpiece W1 around the spindle center line AX1. After front machining, the workpiece W1 is transferred from the front spindle 11A to the back spindle 11B. The back spindle 11B releasably grips the workpiece W1 after front machining with the gripper 12B and is rotatable together with the workpiece W1 around the spindle center line AX1. The motor 13B rotates the back spindle 11B together with the workpiece W1 around the spindle center line AX1. After front machining, the workpiece W1 is turned into a finished product by back machining.

[0023] The tool rest 20 is attached with multiple tools TO1 for machining the workpiece W1 and is movable in the X-axis and Y-axis directions. The X-axis and Y-axis directions are examples of the feed axis F1. Of course, the tool rest 20 may also move in the Z-axis direction. The tool rest 20 may be a turret tool rest or a comb tool rest, etc. The multiple tools TO1 include cutting tools including cut-off tools, rotary tools such as rotary drills and end mills, etc. The feed drive unit U2 moves the tool rest 20, to which the multiple tools TO1 are attached, along the feed axis F1. In this specific example, the drive target of the feed drive unit U2 is the tool TO1, and the feed drive unit U2 moves the tool TO1 along the feed axis F1. The feed axis F1 may be a virtual axis that interpolates the two axes, the X-axis and the Y-axis. If the tool rest 20 to which the tool TO1 is attached can also move in the Z-axis direction, the feed axis F1 may be the Z-axis, or a virtual axis that interpolates the three axes, the X-axis, the Y-axis, and the Z-axis. Even if the tool rest 20 does not move in the Z-axis direction, the headstock 10 to which the spindle 11 is incorporated can move in the Z-axis direction, thereby setting the feed axis F1 that interpolates the three axes and drives both the tool TO1 and the spindle 11. In either case, the direction along the feed axis F1 is the cutting direction.

[0024] The external computer 100 connected to the NC device 70 includes a CPU (Central Processing Unit) 101, which is a processor; a ROM (Read Only Memory) 102, which is a semiconductor memory; a RAM (Random Access Memory) 103, which is a semiconductor memory; a storage device 104; an input device 105; a display device 106; an audio output device 107; an I / F (Interface) 108; a clock circuit 109; and the like. The control program of the computer 100 is stored in the storage device 104, read by the CPU 101 into the RAM 103, and executed by the CPU 101. The storage device 104 may be a semiconductor memory such as a flash memory, a magnetic recording medium such as a hard disk, or the like. The input device 105 may be a pointing device, a keyboard, a touch panel attached to the surface of the display device 106, or the like. The I / F 108 is connected to the NC device 70 by wire or wirelessly and receives data from the NC device 70 and transmits data to the NC device 70. The connection between the computer 100 and the machine tool 1 may be a network connection such as the Internet or an intranet. The computer 100 includes personal computers including tablet terminals, mobile phones such as smartphones, and the like.

[0025] FIG. 2 shows a schematic diagram of the electrical circuit configuration of the machine tool 1. In the machine tool 1 shown in FIG. 2, an NC unit 70 is connected to an operation unit 80, a rotation drive unit U1 for the spindle 11, a headstock drive unit 14, a feed drive unit U2 for the tool rest 20, and other components. The rotation drive unit U1 includes a motor 13A and a servo amplifier (not shown) for rotating the front spindle 11A, and a motor 13B and a servo amplifier (not shown) for rotating the rear spindle 11B. The headstock drive unit 14 includes a front headstock drive unit 14A and a rear headstock drive unit 14B. The feed drive unit U2 includes servo amplifiers 31 and 32 and servo motors 33 and 34. The NC unit 70 includes a CPU 71 (a processor), a ROM 72 (a semiconductor memory), a RAM 73 (a semiconductor memory), a clock circuit 74, an I / F 75, and other components. Therefore, the NC unit 70 is a type of computer. In FIG. 2, the interfaces for the operation unit 80, rotation driver U1, headstock driver 14, feed driver U2, external computer 100, etc. are collectively referred to as I / F 75. A control program PR1 for interpreting and executing the machining program PR2, an assistance program PR3 for assisting in the creation of the machining program PR2, etc. are written in ROM 72. ROM 72 may be a rewritable semiconductor memory. The machining program PR2 created by the operator is rewritably stored in RAM 73. The machining program is also called an NC program. The CPU 71 uses RAM 73 as a work area and executes the control program PR1 stored in ROM 72 to realize the functions of the NC device 70. Of course, some or all of the functions realized by the control program PR1 may be realized by other means, such as an ASIC (Application Specific Integrated Circuit).

[0026] The operation unit 80 includes an input unit 81 and a display unit 82, and functions as a user interface for the NC device 70. In this specific example, the display unit 82 is an example of the display unit U3, and the NC device 70 and the input unit 81 are examples of the control unit U4. The input unit 81 is composed of, for example, buttons and a touch panel for receiving operation inputs from the operator. The display unit 82 is composed of, for example, a display for displaying the contents of various settings received as operation inputs from the operator and various information related to the machine tool 1. The operator can store the machining program PR2 in the RAM 73 using the operation unit 80 and the computer 100.

[0027] The feed drive unit U2 includes a servo amplifier 31 connected to the NC device 70 and a servo motor 33 connected to the servo amplifier 31 in order to move the tool post 20 along the X axis. The feed drive unit U2 also includes a servo amplifier 32 connected to the NC device 70 and a servo motor 34 connected to the servo amplifier 32 in order to move the tool post 20 along the Y axis.

[0028] The servo amplifier 31 controls the position and movement speed of the tool post 20 in the X-axis direction in accordance with commands from the NC device 70. The servo amplifier 32 controls the position and movement speed of the tool post 20 in the Y-axis direction in accordance with commands from the NC device 70. The servo motor 33 is equipped with an encoder 35, rotates in accordance with commands from the servo amplifier 31, and moves the tool post 20 in the X-axis direction via a feed mechanism and guide (not shown). The servo motor 34 is equipped with an encoder 36, rotates in accordance with commands from the servo amplifier 32, and moves the tool post 20 in the Y-axis direction via a feed mechanism and guide (not shown). A ball screw mechanism or the like can be used as the feed mechanism. A sliding guide such as a combination of a dovetail and a dovetail groove can be used as the guide.

[0029] The NC device 70 issues position commands to the servo amplifiers 31 and 32 during the feed movement of the tool post 20, to which the tool TO1 is attached. The servo amplifier 31 receives an X-axis position command from the NC device 70, receives position feedback based on the output from the encoder 35 of the servo motor 33, corrects the position command based on the position feedback, and outputs a torque command to the servo motor 33. This allows the NC device 70 to control the position of the tool post 20 during the feed movement along the X axis. The NC device 70 can also be said to control the position of the tool TO1 during the feed movement along the X axis. The servo amplifier 32 also receives a Y-axis position command from the NC device 70, receives position feedback based on the output from the encoder 36 of the servo motor 34, corrects the position command based on the position feedback, and outputs a torque command to the servo motor 34. This allows the NC device 70 to control the position of the tool post 20 during the feed movement along the Y axis. This can also be said to control the position of the tool TO1 during the feed movement along the Y axis.

[0030] Although not shown, the headstock drive unit 14 also has a servo amplifier and a servo motor. The front headstock drive unit 14A moves the front headstock 10A in the Z-axis direction via a feed mechanism and guide (not shown), and the back headstock drive unit 14B moves the back headstock 10B in the Z-axis direction via a feed mechanism and guide (not shown).

[0031] When tool TO1 attached to tool rest 20 cuts workpiece W1, chips, also known as swarf, are produced. If feed drive unit U2 cuts tool TO1 into workpiece W1, which rotates around spindle center line AX1, without vibrating it along feed axis F1, continuous, long chips are produced. These continuous, long chips may affect the machining of workpiece W1 by wrapping around tool TO1. Therefore, as shown in Figure 3, when cutting workpiece W1, tool TO1 is fed forward and backward repeatedly along feed axis F1, using vibration cutting to break up the chips. The degree to which chips are broken up varies depending on the phase of spindle 11, the amplitude of vibration, the feed rate during forward movement, and the feed rate during backward movement.

[0032] FIG. 3 shows a schematic diagram of the tool position relative to the spindle rotation angle when the chip length coefficient A1, an example of the first parameter related to the vibration period, is 2. The chip length coefficient A1 indicates the number of rotations of the spindle 11 (front spindle 11A or back spindle 11B) required for one vibration period, and can also be considered the number of spindle rotations required for one tool miss. A tool miss refers to a situation in which cutting of the workpiece W1 is not performed due to the vibration of the tool TO1. Hereinafter, a tool miss will be simply referred to as a miss. The spindle rotation angle is the rotation angle of the spindle 11, with the rotation angle when the tool TO1 is at the current position P1 being 0°. The tool position is the controlled position of the tool TO1 in the cutting direction (feed axis F1), with the position when the tool TO1 is at the current position P1 being 0°. The two-dot chain line extending from the current position P1 to the end point P2 indicates the tool position 201 during normal cutting, not vibration cutting. The broken solid line extending from the current position P1 to the end point P2 indicates the tool position 202 during vibration cutting. The bottom of Figure 3 shows an enlarged view of one vibration cycle of the tool position relative to the spindle rotation angle. The tool position shown in Fig. 3 is a position controlled by the NC device 70, and therefore the actual tool position will deviate from the position shown due to delays in the response of the servo system, etc. The same applies to the tool positions shown in Figs. 4 to 8. Note that the specific values ​​shown in Fig. 3 etc. are merely examples.

[0033] The vibration shown in Figure 3 represents alternating forward movement M1, in which tool TO1 moves toward workpiece W1 along the cutting direction, and backward movement M2, in the opposite direction to forward movement M1. The NC device 70 controls the feed movement of tool TO1 so that vibrations including forward movement M1 and backward movement M2 occur when cutting workpiece W1. The broken line of tool position versus spindle rotation angle includes a first change point C1, where forward movement M1 changes to backward movement M2, and a second change point C2, where backward movement M2 changes to forward movement M1. In the example shown in Figure 3, a waveform in which triangular vibration is superimposed on a normal cutting feed is shown as the waveform of tool position versus spindle rotation angle.

[0034] In FIG. 3, the normal cutting feedrate F is the feedrate of the tool TO1 when performing normal cutting, not vibration cutting, and is the feedrate of the tool TO1 when not vibrating. The normal cutting feedrate F is measured in units of, for example, mm / rev, which indicates millimeters per revolution of the spindle. The chip length coefficient A1 is the number of revolutions of the spindle 11 required for one vibration cycle of the tool TO1, which can be said to be the vibration cycle expressed in terms of the number of revolutions of the spindle 11. The chip length coefficient A1 is measured in units of, for example, rev. The chip length coefficient A1 is a positive value excluding at least 1 rev. The forward movement amount D is the distance the position of the tool TO1 changes per vibration cycle and indicates the relative end position of each forward movement M1 (the position of the first change point C1). The forward movement amount D is measured in units of, for example, mm. The retreat movement amount E1 is the distance of the retreat movement M2 during one vibration cycle of the tool TO1 and indicates the relative end position of each retreat movement M2 (the position of the second change point C2). The unit of the retraction amount E1 is, for example, mm. The distance that the tool TO1 moves during the forward movement in one vibration cycle of the tool TO1 is D+E1. In this specific example, if A1>1, in one vibration cycle, the tool TO1 is first controlled to perform a forward movement M1 of a distance (D+E1) / 2, then controlled to perform a retraction movement M2 of the retraction amount E1, and finally controlled to perform a forward movement M1 of a distance (D+E1) / 2.

[0035] In order to control the position of tool TO1 during vibration cutting, the speed of tool TO1 during forward movement (hereinafter referred to as forward movement feed rate Fd) and the speed of tool TO1 during backward movement (hereinafter referred to as backward movement feed rate B) are required. Therefore, a vibration feed command that specifies the speeds Fd and B as a command for the machining program PR2 can be considered, for example, a vibration feed command CM2 as shown in FIG. 12. Here, it is assumed that this vibration feed command has the format "G*** X(U)_Y(V)_Z(W)_D**_F**_E**_B**_J**". The "***" after G indicates the number of the vibration feed command, "X(U)_Y(V)_Z(W)" indicates the position of the end point P2, the "**" after D indicates the numerical value of the forward amount D, the "**" after F indicates the numerical value of the feed speed Fd for the forward movement, the "**" after E indicates the numerical value of the backward amount E1, the "**" after B indicates the numerical value of the feed speed B for the backward movement, and the "**" after J indicates the waiting time at the backward position (dwell in Figure 12). For the above vibration feed command, it is necessary to set the vibration conditions by trial and error by adjusting a number of parameters, at least the forward movement amount D, the forward movement feed rate Fd, the backward movement amount E1, and the backward movement feed rate B.

[0036] In this specific example, by setting the "normal cutting feed rate F," "chip length coefficient A1," and "retraction amount E1," trial and error adjustment of parameters such as the feed rate Fd for forward movement and the feed rate B for retraction movement is not required. The control of vibration cutting in this specific example will be explained in detail below.

[0037] Fig. 3 shows an example of setting a first change point C1 and a second change point C2 in one cycle of vibration when A1>1, specifically A1=2. Fig. 4 shows a schematic example of the tool position relative to the spindle phase when A1=2. For ease of understanding, the tool position in even-numbered cycles is shown by a dashed line in Fig. 4. In order to reduce the load applied to mechanisms such as the feed mechanism and guides, it is preferable to make the speeds Fd,B, the forward movement amount D, and the backward movement amount E1 as small as possible. The dry run is most efficiently performed when the peak (first change point C1) and valley (second change point C2) of the movement path of the tool TO1 coincide at the phase of the main shaft 11. In order to make the peak and valley coincide, for example, from the spindle rotation angle at the middle (A1 / 2) in one cycle of vibration, the peak may be set at a spindle rotation angle of -180°, and the valley may be set at a spindle rotation angle of +180°. When A1 = 2, if the peak is set at a spindle rotation angle of (2 / 2)×360 - 180 = 180°, and the valley is set at a spindle rotation angle of (2 / 2)×360 + 180 = 540°, the spindle phases of the peak and valley coincide as shown in FIG. 4. Since the difference in the spindle rotation angles between the peak and valley is 360° and the backward movement amount E1 is greater than 0, the valley (second change point C2) in the next even cycle is slightly backward from the peak (first change point C1) in the odd cycle. Thereby, the chip is broken. Also, since the change in the tool position during the forward movement is constant, the chip is efficiently broken.

[0038] FIG. 5 schematically illustrates the tool position with respect to the spindle rotation angle when A1 = 3. When A1 = 3, if the peak (first change point C1) is set at a spindle rotation angle of (3 / 2)×360 - 180 = 360°, and the valley (second change point C2) is set at a spindle rotation angle of (3 / 2)×360 + 180 = 720°, the spindle phases of the peak and valley coincide. Thereby, the chip is efficiently broken. When the "chip length coefficient A1" is greater than 1, it is not limited to an integer. When A1 > 3, 2 < A1 < 3, or 1 < A1 < 2, the peak and valley can be set in the same way. However, when 1 < A1 < 2, the feed speed Fd during the forward movement may become excessive, so A1 is preferably 2 or more.

[0039] Although not shown, it is also possible to set the valley (second change point C2) at a spindle rotation angle of -180° and the peak (first change point C1) at a spindle rotation angle of +180° from the spindle rotation angle at the middle (A, / 2) in one cycle of vibration From the above, when A1>1, the NC device 70 controls the difference in spindle rotation angle between the first change point C1 where the forward motion M1 changes to the backward motion M2 in one cycle of vibration and the second change point C2 where the backward motion M2 changes to the forward motion M1 in one cycle of vibration to be 360°.

[0040] If A1>2, it is also possible to set a trough or a peak at a spindle rotation angle of -360° from the intermediate (A1 / 2) spindle rotation angle in one vibration cycle, and to set a peak or a trough at a spindle rotation angle of +360°. If A1>3, it is also possible to set a trough or a peak at a spindle rotation angle of -540° from the intermediate (A1 / 2) spindle rotation angle in one vibration cycle, and to set a peak or a trough at a spindle rotation angle of +540°. In order to reduce the number of spindle rotations required to break up chips and to break up chips more finely, it is most efficient to set a peak or a trough at a spindle rotation angle of -180° from the intermediate (A1 / 2) spindle rotation angle in one vibration cycle, and to set a trough or a peak at a spindle rotation angle of +180°.

[0041] In order for the NC device 70 to move the tool TO1 in the cutting direction (feed axis F1) without changing the feed movement speed from the command speed for normal cutting, it is sufficient to control the overall movement amount of the tool TO1 per one revolution of the spindle to be the same as the normal cutting feed rate F, which is the movement amount during normal cutting. Since the chip length coefficient A1 is the number of revolutions of the spindle 11 required for one cycle of vibration of the tool TO1, the movement amount of the tool TO1 along the cutting direction per one cycle of vibration is A1 x F. As shown in Figures 3 and 5, the tool TO1 is controlled to perform a forward movement M1 of a distance (D + E1) / 2, a retraction movement M2 of a retraction amount E1, and a forward movement M1 of a distance (D + E1) / 2 in one cycle of vibration, in that order. Therefore, A1×F={(D+E1) / 2}×2-E1 From the above equation, the advance amount D is expressed by the following equation. D = A1 × F …(1)

[0042] The feed rate Fd of the forward movement of the tool TO1 is expressed by the following formula. Fd={(D+E1) / 2} / {(A1-1) / 2} =(D+E1) / (A1-1) =(A1×F+E1) / (A1-1) …(2) The feed rate Fd for the forward movement is the maximum feed rate (Fmax) of the tool TO1. The feed rate B of the retraction movement of the tool TO1 is expressed by the following formula. B=E1 / 1 =E1 …(3)

[0043] As described above, when the NC device 70 receives input of the "normal cutting feed rate F," "chip length coefficient A1," and "retraction amount E1" for the cutting direction (feed axis F1) when A1 > 1, it can determine the forward amount D and speeds Fd and B according to the above formulas (1), (2), and (3). Once the forward amount D and speeds Fd and B are determined, the NC device 70 can control the position of the tool TO1 during feed movement based on the forward amount D and speeds Fd and B for the cutting direction. Therefore, a vibration feed command specifying the "normal cutting feed rate F," "chip length coefficient A1," and "retraction amount E1" can be considered as a command for the machining program PR2, such as the vibration feed command CM1 shown in FIG. 9. Here, it is assumed that this vibration feed command has the format "G*** X(U)_Y(V)_Z(W)_A**_F**_E**." The "***" after G indicates the number of the vibration feed command, "X(U)_Y(V)_Z(W)" indicates the position of the end point P2, the "**" after A indicates the numerical value of the chip length coefficient A1, the "**" after F indicates the numerical value of the normal cutting feed rate F (the feed rate to the end point in Fig. 9), and the "**" after E indicates the numerical value of the retreat amount E1.

[0044] FIG. 6 shows a schematic example of how the NC device 70 controls the position of the tool TO1 during feed movement based on the advance amount D and speeds Fd and B calculated from the vibration feed command CM1. The NC device 70 sets multiple positions P3 in the cutting direction (feed axis F1) from the current position P1 to an end point P2 by repeating forward movement M1 and backward movement M2 based on the forward movement amount D and speeds Fd and B, and issues position commands to the servo amplifier 31 or 32 to sequentially move the tool TO1 to the position P3. In FIG. 6, each position P3 is indicated by a white circle. The set position P3 is not limited to the change points (first change point C1 and second change point C2) or the end point P2, but may also include positions during the forward movement M1 or the backward movement M2. By repeating the above-mentioned position commands, the position of the tool TO1 during the feed movement is controlled to a position based on the forward movement amount D and speeds Fd and B.

[0045] As described above, the operator can perform vibration cutting in the same machining time as normal cutting by simply specifying the "normal cutting feed rate F," "chip length coefficient A1," and "retraction amount E1" in the machining program PR2. Here, as the "chip length coefficient A1" increases, the chip length increases while the amplitude decreases. The optimal values ​​of the "chip length coefficient A1" and "retraction amount E1" depend on the tracking ability of the servo system that moves the tool TO1, and are determined by the spindle rotation speed per unit time and the feed rate of the tool TO1. Therefore, as shown in Figure 10, by preparing information table TA1 with guide values ​​for combinations of the "chip length coefficient A1" and "retraction amount E1" according to the "spindle rotation speed per unit time S" and the "normal cutting feed rate F," the operator can easily specify the "chip length coefficient A1" and "retraction amount E1." As shown in Figure 10, information table TA1 associates multiple combinations of A1 and E1 with each combination of S and F. If the identification number identifying the combination of A1 and E1 is j, then Figure 10 shows that, for example, a combination of S = S1 and F = F1 is associated with multiple combinations expressed as A1 = a1j and E1 = e1j. Information table TA1 shown in Figure 10 can also be considered an information table for outputting multiple recommended combinations of "chip length coefficient A1" and "retraction amount E1" in response to the input of "spindle rotation speed per unit time S" and "normal cutting feed rate F." Of course, the number of combinations of A1 and E1 is finite.

[0046] Therefore, when the "spindle rotation speed S per unit time" and the "normal cutting feed rate F" are determined, it becomes possible to select a combination of "chip length coefficient A1" and "retraction amount E1" from the information table TA1. Although it will be described later in detail with reference to FIG. 9, by previously storing the information table TA1 in the RAM 73 of the NC device 70, the NC device 70 can present recommended values of "chip length coefficient A1" and "retraction amount E1" from the "spindle rotation speed S per unit time" and the "normal cutting feed rate F".

[0047] FIG. 7 schematically illustrates the tool position with respect to the spindle rotation angle when the chip length coefficient A1, that is, the chip length coefficient A1 is 2 / 3. In this specific example, when 0 < A1 < 1, in one cycle of vibration, for the tool TO1, in the first half, control of the forward movement M1 of the distance (D + E1) is performed, and in the second half, control of the retraction movement M2 of the retraction amount E1 is performed. FIG. 8 schematically illustrates the tool position with respect to the spindle phase when A1 = 2 / 3. When 0 < A1 < 1, in order to efficiently realize dry running, the "chip length coefficient A1" is restricted such that A1 = 2 / 3, 2 / 5, 2 / 7,... and the denominator is an odd number of 3 or more and the numerator is 2. In order to make the peak (first change point C1) and the valley (second change point C2) coincide at the phase of the spindle 11, for example, the peak may be set at the spindle rotation angle of the middle (A1 / 2) in one cycle of vibration, and the valley may be set at the spindle rotation angle of the end (A1) in one cycle of vibration. When A1 = 2 / 3, if the peak is set at the spindle rotation angle of (2 / 3) / 2 × 360 = 120°, and the valley is set at the spindle rotation angle of (2 / 3) × 360 = 240°, as shown in FIG. 8, the spindle phases of the peak and the valley coincide. The spindle phases where the peak and the valley coincide are 120°, 240°, and 360°.

[0048] When A1 = 2 / 5, if the peak is set at the spindle rotation angle of (2 / 5) / 2 × 360 = 72°, and the valley is set at the spindle rotation angle of (2 / 5) × 360 = 144°, the spindle phases of the peak and the valley coincide. The spindle phases where the peak and the valley coincide are 72°, 144°, 216°, 288°, and 360°. The "chip length coefficient A1" may be 2 / 7 or less. However, if A1<2 / 3, the feed rate of the tool TO1 and the number of revolutions of the spindle 11 per unit time may need to be significantly reduced in terms of the follow-up of the servo system for control, so A1 is preferably 2 / 3.

[0049] Although not shown, it is also possible to set a valley at the spindle rotation angle at the middle (A1 / 2) in one vibration cycle and a peak at the spindle rotation angle at the end (A1) in one vibration cycle. As described above, when the denominator of the "chip length coefficient A1" is an odd number equal to or greater than 3 and the numerator of the "chip length coefficient A1" is 2, the NC device 70 controls the difference in spindle rotation angle between the first change point C1 at which the forward motion M1 changes to the backward motion M2 in one cycle of vibration and the second change point C2 at which the backward motion M2 changes to the forward motion M1 in one cycle of vibration to be {(A1 / 2) × 360}°.

[0050] In order for the NC device 70 to move the tool TO1 in the cutting direction (feed axis F1) without changing the feed movement speed from the command speed for normal cutting, it is sufficient to control the overall movement amount of the tool TO1 per one revolution of the spindle to be the same as the normal cutting feed rate F, which is the movement amount during normal cutting. As described above, the movement amount of the tool TO1 along the cutting direction per one cycle of vibration is A1 x F. As shown in Figures 7 and 8, the tool TO1 is controlled to move forward M1 by a distance (D + E1) and move backward M2 by a backward amount E1 in one cycle of vibration, in that order. Therefore, A1×F=(D+E1)-E1 From the above equation, the advance amount D is expressed by the following equation. D = A1 × F …(4)

[0051] The feed rate Fd of the forward movement of the tool TO1 is expressed by the following formula. Fd=(D+E1) / (A1 / 2) =2(D+E1) / A1 =2(A1×F+E1) / A1 …(5) Again, the feedrate Fd for the forward movement is the maximum feedrate Fmax of tool TO1. The feed rate B of the retraction movement of the tool TO1 is expressed by the following formula. B=E1 / (A1 / 2) =2E1 / A1 …(6)

[0052] As described above, when A1<1, the NC device 70 receives inputs of the "normal cutting feed rate F," "chip length coefficient A1," and "retraction amount E1" for the cutting direction (feed axis F1), and can determine the forward movement amount D and speed Fd,B according to the above equations (4), (5), and (6). Once the forward movement amount D and speed Fd,B are determined, the NC device 70 can control the position of the tool TO1 during feed movement based on the forward movement amount D and speed Fd,B in the cutting direction. As shown in FIG. 6 , the NC device 70 sets multiple positions P3 in the cutting direction from the current position P1 to the end point P2 by repeating forward movement M1 and retraction movement M2 based on the forward movement amount D and speed Fd,B, and sequentially issues position commands to the servo amplifier 31 or 32 to move the tool TO1 to position P3. By repeating the above position commands, the position of the tool TO1 during feed movement is controlled to a position based on the forward movement amount D and speed Fd,B.

[0053] The feed rate of tool TO1 is an important cutting condition when selecting tool TO1, as it prevents chipping and welding of tool TO1. Tool manufacturers provide guidelines for appropriate feed rates, which vary depending on the workpiece material, tool material, and type. The NC device 70 executing the vibration feed command CM1 automatically calculates the forward movement D and speeds Fd and B from the parameters F, A1, and E1, setting the machining time during vibration cutting to the same as that during normal cutting. Therefore, the calculated forward movement feed rate Fd is greater than the normal cutting feed rate F. Because the operator does not know the forward movement feed rate Fd, which is the maximum feed rate Fmax, he or she is unable to properly select tool TO1 and therefore is unable to properly set the parameters for vibration cutting. Therefore, in this specific example, in order to assist in the creation of the vibration feed command CM1, a value representing the maximum feed rate Fmax according to the parameters F, A1, and E1 is displayed on the display unit 82 (see Figure 2), thereby facilitating the selection of tools and the setting of the parameters F, A1, and E1.

[0054] 9 is a schematic diagram illustrating a setting screen for the vibration feed command CM1. When the NC device 70 receives an instruction from the input unit 81 to display a screen 501 that supports creation of the vibration feed command CM1 from a menu screen (not shown), the NC device 70 performs processing to display the screen 501 shown in FIG. A screen 501 shown in FIG. 9 has a spindle speed input field 511, a movement distance input field 512, a feed rate input field 513 to the end point, a chip length coefficient input field 514, a retraction amount input field 515, a command input field 516, a format switching button 521, an Fmax value prediction button 522, a division check button 523, a command copy button 524, a recommended value setting button 525, a vibration waveform display field 530, and the like.

[0055] The "spindle rotation speed S per unit time" can be input in the spindle rotation speed input field 511. The unit of the "spindle rotation speed S per unit time" is, for example, rev / min. The movement distance input field 512 can be input with the "movement distance W," which is the total distance the tool TO1 is moved from the movement start position to the movement end position along the cutting direction (feed axis F1) while the vibration feed command CM1 is being executed. The unit of the "movement distance W" is, for example, mm. Note that the "movement distance W" is different from the W of the end point "X(U)_Y(V)_Z(W)" included in the vibration feed command CM1. The feed rate to the end point input field 513 can be input with the "normal cutting feed rate F." The unit of the "normal cutting feed rate F" is, for example, mm / rev. The chip length coefficient input field 514 can be input with the "chip length coefficient A1." The unit of the "chip length coefficient A1" is, for example, rev. In addition, in Fig. 9, it is shown as "chip length coefficient A." The same applies to Fig. 11. In the retraction amount input field 515, it is possible to input "retraction amount E1." The unit of "retraction amount E1" is, for example, mm. In addition, in Fig. 9, it is shown as "retraction amount E." The same applies to Figs. 11 and 12. By operating the recommended value setting button 525, the operator can display the recommended value of "chip length coefficient A1" in the chip length coefficient input field 514 and the recommended value of "retraction amount E1" in the retraction amount input field 515. In order to display these recommended values, the information table TA1 shown in Fig. 10 is stored in the RAM 73, and the NC device 70 performs the following processing.

[0056] When the NC device 70 receives an operation of the recommended value setting button 525 via the input unit 81, it displays one of the combinations of "chip length coefficient A1" and "retraction amount E1" that are associated in the information table TA1 with the combination of "spindle rotation speed S per unit time" input in the spindle rotation speed input field 511 and "normal cutting feed rate F" input in the feed rate input field 513, in the chip length coefficient input field 514 and the retraction amount input field 515. If there are multiple combinations of A1 and E1 that are associated with the combination of S and F in the information table TA1, the NC device 70 may switch the combination of A1 and E1 and display it in the chip length coefficient input field 514 and the retraction amount input field 515 each time it receives an operation of the recommended value setting button 525. Of course, the NC device 70 can accept a change to the "chip length coefficient A1" when the recommended value for the "chip length coefficient A1" is displayed in the chip length coefficient input field 514, and can accept a change to the "retraction amount E1" when the recommended value for the "retraction amount E1" is displayed in the retraction amount input field 515.

[0057] With values ​​entered in the above-mentioned input fields (511 to 515), the operator can operate the Fmax value prediction button 522 to display values ​​representing the maximum feed rate Fmax and cutting time (CT) according to the parameters F, A1, and E1. The unit of the maximum feed rate Fmax is, for example, mm / rev. The cutting time CT is the time required for the tool TO1 to move with vibration from the current position P1 to the end point P2 (see Figure 3) in accordance with the vibration feed command CM1. If the unit of the number of spindle rotations S per unit time is rev / min, the unit of the cutting time CT is min.

[0058] When the NC device 70 receives operation of the Fmax value prediction button 522 at the input unit 81, it first calculates the "maximum feed rate Fmax" of the tool TO1 based on the "normal cutting feed rate F," "chip length coefficient A1," and "recession amount E1" for the cutting direction (feed axis F1). When A1>1, the maximum feed rate Fmax is expressed by the following formula from the above formula (2) which calculates the feed rate Fd for forward movement from the parameters F, A1, and E1. Fmax = (A1 × F + E1) / (A1 - 1) ... (7) When A1<1, the maximum feed rate Fmax is expressed by the following equation from the above equation (5) which calculates the feed rate Fd for the forward movement from the parameters F, A1, and E1. Fmax=2(A1×F+E1) / A1 …(8)

[0059] Furthermore, the NC device 70 calculates the "cutting time CT" of the vibration feed command CM1 based on the "number of spindle rotations per unit time S," "movement distance W," and "normal cutting feed rate F" for the cutting direction. The "cutting time CT" is expressed by the following formula. CT=W / (F×S) …(9)

[0060] The NC device 70 calculates the maximum feed rate Fmax according to the above formula (7) or (8), and calculates the cutting time CT according to the above formula (9), and then displays the results as predictions on a screen 501 shown in Fig. 9. For example, the NC device 70 displays a numerical value representing the maximum feed rate Fmax in mm / rev units, and a numerical value representing the cutting time CT in minutes and seconds. As described above, values ​​representing the maximum feed rate Fmax and cutting time CT, which cannot be determined from the values ​​in the input fields (511 to 515), are displayed on the display unit 82. By looking at the value representing the cutting time CT, the operator can easily determine whether the vibration feed command CM1 is the desired cutting time CT. Furthermore, by looking at the value representing the maximum feed rate Fmax, the operator can easily select the tool TO1 for vibration cutting, and can easily set the parameters for vibration cutting.

[0061] Furthermore, based on the parameters F, A1, and E1, the NC device 70 displays the vibration waveform of the tool position relative to the spindle phase in the vibration waveform display field 530. The area where the vibration waveforms overlap at different spindle rotation angles is the chip separation region.

[0062] The operator can input the vibration feed command CM1 into the command input field 516 by operating the command copy button 524. When the NC device 70 receives the operation of the command copy button 524 at the input unit 81, it creates the vibration feed command CM1 based on the parameters F, A1, and E1 and displays it in the command input field 516. Furthermore, the NC device 70 performs processing to incorporate the vibration feed command CM1 input into the command input field 516 into the machining program PR2.

[0063] After looking at the displayed maximum feed rate Fmax, the operator may wish to change the maximum feed rate Fmax to match the cutting conditions of tool TO1. For example, if the maximum feed rate Fmax exceeds the upper limit of the feed rate of the tool TO1 available, the operator may wish to slow down the maximum feed rate Fmax to match the upper limit of the feed rate of tool TO1. Also, slowing down the maximum feed rate Fmax may be considered when improving the edge retention of tool TO1 or the surface roughness of workpiece W1. A slower maximum feed rate Fmax extends the cutting time CT. Conversely, if the maximum feed rate Fmax is slower than the upper limit of the feed rate of tool TO1, the operator may wish to shorten the cutting time CT by increasing the maximum feed rate Fmax within the range that does not exceed the upper limit of the feed rate of tool TO1. Additionally, the operator may wish to know how much the cutting time CT changes as the maximum feed rate Fmax changes.

[0064] Therefore, in this specific example, a screen 502 (see FIG. 11) for changing the value representing the displayed maximum feed speed Fmax is displayed on the display unit 82, thereby making it easy to change the maximum feed speed Fmax.

[0065] 11 is a schematic diagram illustrating a screen 502 that accepts a change in the maximum feed rate Fmax. For example, the NC device 70 may display a dialog box (not shown) that asks "Do you want to change the maximum feed rate Fmax?" on the screen 501 shown in FIG. 9 together with the prediction result, and may display the screen 502 shown in FIG. 11 on the display unit 82 when an operation to switch the screen is accepted by the input unit 81. Furthermore, the NC device 70 may display the screen 502 shown in FIG. 11 on the display unit 82 when an operation to switch the screen is accepted by the input unit 81 using a screen switching button (not shown) provided on the screen 501 shown in FIG. 9. The screen 502 shown in FIG. 11 has a maximum feedrate input field 517 instead of the feedrate to end point input field 513 shown in FIG. 9 , and an F-value prediction button 526 instead of the Fmax value prediction button 522. The NC device 70 displays the values ​​entered on the screen 501 shown in FIG. 9 in the spindle rotation speed input field 511, the travel distance input field 512, the chip length coefficient input field 514, and the retraction amount input field 515. Because no processing is performed to display recommended values ​​in the chip length coefficient input field 514 and the retraction amount input field 515, the screen 502 does not have a recommended value setting button 525. The NC device 70 displays the value of the maximum feedrate Fmax shown in FIG. 9 in the maximum feedrate input field 517 and accepts an operation to change the maximum feedrate Fmax via the input unit 81. Therefore, the operator can change the maximum feedrate Fmax to suit the tool TO1, etc.

[0066] With values ​​entered in the above-mentioned input fields (511, 512, 517, 514, 515), the operator can operate the F-value prediction button 526 to display values ​​representing the normal cutting feed rate F and cutting time CT according to the parameters Fmax, A1, and E1.

[0067] When the NC device 70 receives an operation of the F value prediction button 526 at the input unit 81, it first calculates the "normal cutting feed rate F" of the tool TO1 based on the "maximum feed rate Fmax," "chip length coefficient A1," and "retraction amount E1" for the cutting direction (feed axis F1). When A1>1, the normal cutting feed rate F is expressed by the following equation from the above equation (7). F={Fmax×(A1-1)-E1} / A1…(10) When A1<1, the normal cutting feed rate F is expressed by the following equation from the above equation (8). F = (Fmax / 2) - (E1 / A1) ... (11)

[0068] Furthermore, the NC device 70 calculates the "cutting time CT" of the vibration feed command CM1 based on the "number of spindle rotations per unit time S" and "movement distance W" for the cutting direction, and the changed "normal cutting feed rate F." The "cutting time CT" is expressed by the following formula. CT=W / (F×S) …(12) The changed “normal cutting feed rate F” is calculated based on the changed “maximum feed rate Fmax,” “chip length coefficient A1,” and “recession amount E1.” Therefore, the changed cutting time CT is calculated based on the changed “maximum feed rate Fmax,” “chip length coefficient A1,” and “recession amount E1.”

[0069] The NC device 70 calculates the normal cutting feedrate F according to the above formula (10) or (11), calculates the cutting time CT according to the above formula (12), and displays the predicted results on the screen 502 shown in Fig. 11. For example, the NC device 70 displays a numerical value representing the changed normal cutting feedrate F in mm / rev as the "feedrate F to the end point," and displays a numerical value representing the changed cutting time CT in minutes and seconds. The example shown in Figs. 9 and 11 shows that the normal cutting feedrate F has changed from 0.03 mm / rev to 0.02 mm / rev as a result of changing the maximum feedrate Fmax from 0.07 mm / rev to 0.05 mm / rev. As a result, values ​​representing the normal cutting feedrate F and cutting time CT, which cannot be determined from the values ​​in the input fields (511, 512, 517, 514, 515), are displayed on the display unit 82. The operator can change the maximum feedrate Fmax to match the tool TO1, etc., and can also confirm the normal cutting feedrate F. Furthermore, by looking at the value representing the changed cutting time CT, the operator can confirm the cutting time CT required for the feed movement of tool TO1 that involves vibration at the changed maximum feedrate Fmax.

[0070] The operator can input the vibration feed command CM1 into the command input field 516 by operating the command copy button 524. When the NC device 70 receives the operation of the command copy button 524 at the input unit 81, it creates the vibration feed command CM1 based on the changed "normal cutting feed rate F," the "chip length coefficient A1" input into the chip length coefficient input field 514, and the "retraction amount E1" input into the retraction amount input field 515, and displays the vibration feed command CM1 in the command input field 516. In addition, the NC device 70 performs processing to incorporate the vibration feed command CM1 input into the command input field 516 into the machining program PR2.

[0071] 11, together with the display of the prediction result, and when an operation to switch the screen is accepted by the input unit 81, the NC device 70 may display the screen 501 shown in Fig. 9 on the display unit 82. Furthermore, when an operation of a screen switching button (not shown) provided on the screen 502 shown in Fig. 11 is accepted by the input unit 81, the NC device 70 may display the screen 501 shown in Fig. 9 on the display unit 82.

[0072] 9 and 11, the operator can create a vibration feed command CM2, as shown in Fig. 12, by operating a format switching button 521. Fig. 12 schematically illustrates a setting screen for the vibration feed command CM2. When the NC device 70 receives an operation of the format switching button 521, as shown in Figs. 9 and 11, at the input unit 81, it performs processing to display a screen 503, as shown in Fig. 12, on the display unit 82. The screen 503 shown in FIG. 12 has a spindle rotation speed input field 511, a movement distance input field 512, a forward movement amount input field 541, a forward movement feed rate input field 542, a backward movement amount input field 515, a backward movement feed rate input field 543, a waiting time input field 544 at the backward position, a command input field 516, a format switching button 521, a cutting time prediction button 527, a division check button 523, a command copy button 524, a vibration waveform display field 530, and the like.

[0073] In the forward movement input field 541, an "advance movement amount D" can be input. The unit of the "advance movement amount D" is, for example, mm. In the forward movement feedrate input field 542, an "advance movement feedrate Fd" which is the maximum feedrate Fmax can be input. The unit of the "advance movement feedrate Fd" is, for example, mm / rev. Note that "F" in FIG. 12 does not indicate the "feedrate F to the end point" shown in FIGS. 9 and 11, but indicates the "advance movement feedrate Fd" which is the maximum feedrate Fmax. In the retract movement feedrate input field 543, a "retract movement feedrate B" can be input. The unit of the "retract movement feedrate B" is, for example, mm / rev. In the retract position wait time input field 544, a "wait time J at the retract position" (dwell J at the retract position in FIG. 12) can be input. The unit of the "wait time J at the retract position" is, for example, min.

[0074] With values ​​entered in the input fields (511, 512, 515, 541 to 544) described below, the operator can operate the cutting time prediction button 527 to display a value representing the cutting time CT required for the feed movement of the tool TO1 accompanied by vibration from the current position to the end point in accordance with the vibration feed command CM2.

[0075] When the NC device 70 receives an operation of the cutting time prediction button 527 at the input unit 81, it calculates the "cutting time CT" of the vibration feed command CM2 based on the "number of spindle rotations per unit time S," "movement distance W," "forward amount D," "feed rate Fd for forward movement," "backward amount E1," "feed rate B for backward movement," and "waiting time J at the backward position" for the cutting direction (feed axis F1). The "cutting time CT" is expressed by the following formula.

number

[0076] As a result, the value representing the cutting time CT, which cannot be determined from the values ​​in the input fields (511, 512, 515, 541 to 544), is displayed on the display unit 82. By looking at the value representing the cutting time CT, the operator can easily understand whether the vibration feed command CM2 is the desired cutting time CT.

[0077] The vibration feed command CM2 requires the operator to set the parameters D, Fd, E1, B, and J, so it is not clear whether the parameters D, Fd, E1, B, and J satisfy the conditions for breaking up the chips. Therefore, the operator can check whether the parameters D, Fd, E1, B, and J satisfy the conditions for breaking up the chips by operating the break-up check button 523. For example, when the NC device 70 receives an operation of the breakage check button 523 via the input unit 81, it may display the vibration waveform of the tool position relative to the spindle phase based on the parameters D, Fd, E1, B, and J in the vibration waveform display field 530. The NC device 70 may also display the chip breakage region in the vibration waveform display field 530 when there is a portion where the vibration waveforms overlap at different spindle rotation angles. By looking at the chip breakage region, the operator can confirm that the parameters D, Fd, E1, B, and J satisfy the conditions for breaking the chips. If the chip breakage region is not displayed, the operator can confirm that the parameters D, Fd, E1, B, and J do not satisfy the conditions for breaking the chips.

[0078] When the input unit 81 receives an operation of the format switching button 521 shown in FIG. 12, the NC device 70 performs a process of displaying the screen 501 shown in FIG. 9 on the display unit 82.

[0079] As described above, because a value representing the maximum feed rate (Fmax), which is not present in the vibration feed command CM1 having parameters F, A1, and E1, is displayed on screen 501 (see FIG. 9), the operator can easily select tool TO1 for vibration cutting and set parameters for vibration cutting. Furthermore, if the operator wishes to change the maximum feed rate Fmax, the operator can change the maximum feed rate Fmax (see FIG. 11) and confirm the changed normal cutting feed rate F and cutting time CT. Furthermore, because a value representing the cutting time CT, which is difficult to understand from the vibration feed command CM2 having parameters D, Fd, E1, B, and J, is displayed on screen 503 (see FIG. 12), the operator can also confirm the cutting time CT in the vibration feed command CM2.

[0080] (3) Variation: The present invention can be modified in various ways. For example, the driven object that moves along the cutting direction is not limited to the tool TO1, but may be the spindle 11 that grips the workpiece W1, or may be both the tool TO1 and the spindle 11. When the driven object is the spindle 11, the NC device 70 only needs to control the feed movement of the spindle 11 so that vibration occurs along the cutting direction when cutting the workpiece W1. When the driven objects are both the tool TO1 and the spindle 11, the NC device 70 only needs to control the feed movement of both the tool TO1 and the spindle 11 so that vibration occurs along the cutting direction when cutting the workpiece W1.

[0081] The vibration cutting condition setting device may be provided in a computer 100 (see FIG. 1 ) rather than in a machine tool. In this case, the display device 106 is an example of a display unit U3, and the CPU 101, ROM 102, RAM 103, storage device 104, and input device 105 are examples of a control unit U4. The computer 100 including the vibration cutting condition setting device 3 may be connected to the machine tool 1, or may not be connected to the machine tool 1.

[0082] The value representing the "maximum feed rate Fmax" after the change displayed on the screen 501 shown in Fig. 9 may be the ratio (including percentage) of the "maximum feed rate FmaxF" to the "normal cutting feed rate F" or the difference between the "normal cutting feed rate F" and the "maximum feed rate FmaxF". In this case, the operator can grasp the "maximum feed rate Fmax" relatively. The value indicating the "normal cutting feedrate F" after the change displayed on the screen 502 shown in Fig. 11 may be the ratio (including percentage) of the "normal cutting feedrate F" after the change to the "normal cutting feedrate F" before the change, or the difference between the "normal cutting feedrate F" before the change and the "normal cutting feedrate F" after the change. In this case, the operator can relatively grasp the change in the "normal cutting feedrate F" due to the change in the "maximum feedrate Fmax". The value representing the "cutting time CT" after the change displayed on the screen 502 shown in Fig. 11 may be the ratio (including percentage) of the "cutting time CT" after the change to the "cutting time CT" before the change, or the difference between the "cutting time CT" before the change and the "cutting time CT" after the change. In this case, the operator can relatively grasp the change in the "cutting time CT" due to the change in the "maximum feed rate Fmax".

[0083] 9 and 11, the NC device 70 may accept an operation to change the cutting time CT. In this case, the NC device 70 may calculate a normal cutting feedrate F and a maximum feedrate Fmax based on the cutting time CT before and after the change, and display the calculated normal cutting feedrate F and maximum feedrate Fmax on the screens 501 and 502. For example, when the NC device 70 accepts an operation of a cutting time change button (not shown) provided on the screens 501 and 502 at the input unit 81, the NC device 70 may accept an input of the changed cutting time (referred to as CTa) at the input unit 81.

[0084] Here, the cutting time before the change is CTb, the normal cutting feedrate after the change is Fa, and the normal cutting feedrate before the change is Fb. The normal cutting feedrate after the change, Fa, can be calculated according to the following formula. Fa = (CTb / CTa) × Fb … (14) The NC device 70 may display the normal cutting feed rate Fa thus obtained after the change in the feed rate input field 513 to the end point on the screen 501 or in the predicted result on the screen 502 .

[0085] The maximum feed rate after the change (referred to as Famax) can be calculated from the above-mentioned formulas (7) and (8) according to the following formula. If A1>1, Famax=(A1×Fa+E1) / (A1-1) …(15) If A1<1, Famax=2(A1×Fa+E1) / A1 …(16) The NC device 70 may display the calculated changed maximum feedrate Famax in the prediction result on the screen 501 or in the maximum feedrate input field 517 on the screen 502 .

[0086] The operator can check the normal cutting feed rate F and the maximum feed rate Fmax, which change by changing the cutting time CT, so that the operator can easily select the tool TO1 for vibration cutting and easily set the parameters for vibration cutting. In addition, the NC device 70 may display the changed normal cutting feed rate Fa on the screens 501 and 502 without displaying the changed maximum feed rate Famax on the screens 501 and 502, or may display the changed maximum feed rate Famax on the screens 501 and 502 without displaying the changed normal cutting feed rate Fa on the screens 501 and 502.

[0087] As shown in Fig. 13, this technology can also be applied to a waveform in which a sinusoidal vibration is superimposed on the normal cutting feed as the waveform of the tool position relative to the spindle rotation angle. Fig. 13 schematically shows another example of the tool position relative to the spindle rotation angle. In Fig. 13, the component of the normal cutting feedrate F is shown by a dashed line, and the maximum feedrate Fmax is shown by a fine dotted line. The sine wave obtained by removing the component of the normal cutting feed rate F from the waveform shown in Figure 13 has a period A2 and an amplitude E2. Therefore, the period A2 is an example of a first parameter related to the vibration period, and the amplitude E2 is an example of a second parameter related to the vibration amplitude. The slope of the sine wave shown in Figure 13 at midpoint C5, going from valley C4 to peak C3, indicates the maximum feed rate Fmax. Therefore, the maximum feed rate Fmax can be determined by substituting the spindle rotation angle at midpoint C5 into the feed rate formula obtained by differentiating the formula for calculating the tool position from the spindle rotation angle.

[0088] The NC device 70 (or the computer 100) may display a screen similar to the screen 501 shown in Fig. 9 on the display unit U3 and perform processing to receive the normal cutting feed rate F, the period A2, and the amplitude E2. The NC device 70 may calculate the maximum feed rate Fmax using the calculation method described above based on the normal cutting feed rate F, the period A2, and the amplitude E2, and may perform processing to display a value representing the calculated maximum feed rate Fmax on the display unit U3. As described above, since the value representing the maximum feed rate Fmax, which is unknown in the accepted settings, is displayed, the operator can easily select the tool TO1 for vibration cutting by looking at the value representing the maximum feed rate Fmax, and can easily set the parameters for vibration cutting.

[0089] 11 on the display unit U3, and may change the normal cutting feedrate F by performing the reverse calculation described above based on the changed maximum feedrate Fmax, period A2, and amplitude E2. The NC device 70 may obtain the cutting time CT according to the above-mentioned formula (12), and display the changed normal cutting feedrate F and cutting time CT on the display unit U3. As described above, the changed normal cutting feed rate F and cutting time CT can be confirmed, which makes it easy to set parameters such as the normal cutting feed rate F.

[0090] (4) Conclusion: As explained above, according to the present invention, it is possible to provide a technique that makes it easy to select a tool and set parameters for vibration cutting through various aspects. Of course, even a technique that consists only of the constituent elements of the independent claims can achieve the basic functions and effects described above. Furthermore, it is possible to implement configurations in which the components disclosed in the above examples are substituted with each other or the combination is changed, or configurations in which the components disclosed in the publicly known techniques and the above examples are substituted with each other or the combination is changed, etc. The present invention also includes these configurations. [Explanation of symbols]

[0091] 1...Machine tool, 3...Vibration cutting condition setting device, 10... Headstock, 11... Spindle, 12... Gripping part, 13A, 13B... Motor, 14...headstock drive unit, 20...Tool rest, 31, 32... Servo amplifier, 33, 34... Servo motor, 35, 36... Encoder, 70...NC device, 80... operation unit, 81... input unit, 82... display unit, 100...computer, 201...Tool position during normal cutting, 202...Tool position during vibration cutting, AX1…Spindle center line, C1...first change point, C2...second change point, CM1, CM2... Vibration feed command, F1...feed axis, M1...Forward movement, M2...Backward movement, P1...current position, P2...end point, P3...position, PR1...control program, PR2...machining program, PR3...support program, TO1...Tools, U1...rotation drive unit, U2...feed drive unit, U3...display unit, U4...control unit, W1...Work.

Claims

1. A vibration cutting condition setting device for a machine tool, comprising: a rotation drive unit that rotates a spindle that grips a workpiece; and a feed drive unit that moves at least one of a tool that cuts the workpiece and the spindle as a driven object, and that controls the feed movement of the driven object so as to accompany vibrations including a forward movement of the tool relatively toward the workpiece and a backward movement in the opposite direction to the forward movement along a cutting direction in which the tool moves relatively with respect to the workpiece when cutting the workpiece, A display unit; a control unit that receives a feed speed (F) of the driven object when it is not vibrating, a first parameter (A) related to a period of the vibration, and a second parameter (E) related to an amplitude of the vibration as settings for controlling the feed movement of the driven object so as to accompany the vibration; The control unit a maximum feed rate (Fmax) of the driven object is calculated based on a feed rate (F) of the driven object when it is not vibrating, the first parameter (A), and the second parameter (E) under a condition that a phase of the main spindle at a first change point at which the forward motion changes to the backward motion in one cycle of the vibration is matched with a phase of the main spindle at a second change point at which the backward motion changes to the forward motion in one cycle of the vibration; The value representing the determined maximum feed rate (Fmax) is displayed on the display unit; Accepting an operation to change the maximum feed rate (Fmax) displayed on the display unit; calculating a cutting time (CT) required for the feed movement of the driven object accompanied by the vibration at the changed maximum feed speed (Fmax) based on the changed maximum feed speed (Fmax), the first parameter (A), and the second parameter (E); A vibration cutting condition setting device for a machine tool, which displays a value representing the obtained cutting time (CT) on the display unit.

2. The control unit changing a feed speed (F) of the driven object when it is not vibrating based on the changed maximum feed speed (Fmax), the first parameter (A), and the second parameter (E); 2. The vibration cutting condition setting device for a machine tool according to claim 1, wherein a value representing the changed feed rate (F) of the driven object when it is not vibrating is displayed on the display unit.

3. A vibration cutting condition setting device for a machine tool, comprising: a rotation drive unit that rotates a spindle that grips a workpiece; and a feed drive unit that moves at least one of a tool that cuts the workpiece and the spindle as a driven object, and that controls the feed movement of the driven object so as to accompany vibrations including a forward movement of the tool relatively toward the workpiece and a backward movement in the opposite direction to the forward movement along a cutting direction in which the tool moves relatively with respect to the workpiece when cutting the workpiece, A display unit; a control unit that receives a feed speed (F) of the driven object when it is not vibrating, a first parameter (A) related to a period of the vibration, and a second parameter (E) related to an amplitude of the vibration as settings for controlling the feed movement of the driven object so as to accompany the vibration; The control unit a maximum feed rate (Fmax) of the driven object is calculated based on a feed rate (F) of the driven object when it is not vibrating, the first parameter (A), and the second parameter (E) under a condition that a phase of the main spindle at a first change point at which the forward motion changes to the backward motion in one cycle of the vibration is matched with a phase of the main spindle at a second change point at which the backward motion changes to the forward motion in one cycle of the vibration; The value representing the determined maximum feed rate (Fmax) is displayed on the display unit; Accepting an operation to change the maximum feed rate (Fmax) displayed on the display unit; changing a feed speed (F) of the driven object when it is not vibrating based on the changed maximum feed speed (Fmax), the first parameter (A), and the second parameter (E); A vibration cutting condition setting device for a machine tool, which displays on the display unit a value representing the changed feed rate (F) of the driven object when it is not vibrating.

4. The control unit Accepting an operation to change a cutting time (CT) required for the feed movement of the driven object accompanied by the vibration; Based on the changed cutting time (CT), at least one feed rate parameter of the non-vibration feed rate (F) of the driven object and the maximum feed rate (Fmax) is changed; 4. The vibration cutting condition setting device for a machine tool according to claim 1, wherein a value representing the changed feed rate parameter is displayed on the display unit.

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