Display control device, machine tool, display control program, and display method

Abstract

To provide a display that supports an operator in taking measures against chatter vibration when using a machine tool. [Solution] A display control device of one aspect displays and controls the status of a machine tool having a mounting unit to which a tool can be attached, a numerical control unit that controls movement of the mounting unit and the rotational speed of the tool in accordance with a machining program, and a vibration detection unit that detects vibrations of the tool. The display control device includes a display control unit that controls the display of time-series data indicating changes in vibration level detected by the vibration detection unit and changes in the rotational speed of the tool. When an instruction to change the rotational speed is received, the display control unit controls the display so that a marker indicating the change instruction is superimposed on the time-series data.

Description

[Technical Field]

[0001] The present invention relates to a display control technique for supporting countermeasures against chatter vibrations that occur in machine tools. [Background technology]

[0002] In machine tools, chatter vibrations can lead to a decrease in the quality of the machined surface of the workpiece, so it is important to suppress their occurrence. Chatter vibrations can occur for a variety of reasons. Sometimes the source of vibration is the tool, and other times it is the workpiece. To identify and eliminate the cause, operators often rely on their own experience to address the issue. For example, they listen to the sound of vibrations and observe the machined surface of the workpiece to predict the cause of the chatter vibrations, then adjust the spindle rotation speed, feed rate, cutting depth, cutting width, etc. If the chatter vibrations persist, they may try changing the way the workpiece is fixed or the tool. These types of measures are selected based on the operator's own experience and knowledge.

[0003] There are several causes of chatter vibration. The main causes are regenerative chatter, which occurs when vibration-induced undulations on the machined surface cause fluctuations in the cutting depth of the tool, and forced chatter, which occurs due to resonance based on the natural frequency. A technology has been proposed that assists the operator in controlling chatter vibration when it occurs (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6456434 Summary of the Invention [Problem to be solved by the invention]

[0005] It is desirable for operators to record their operations in detail so that they can later determine whether their countermeasures against chatter vibration were effective and, if so, what kind of operations they performed. This makes it easier to efficiently eliminate chatter vibration if it occurs again. However, it is not easy for operators to record their operations simultaneously with machine operations. In particular, because feature quantities such as the magnitude and frequency of chatter vibration change constantly during machining, there is a possibility that a time lag will occur between the operation content and the operation timing if the operator manually records the operations. [Means for solving the problem]

[0006] One aspect of the present invention is a display control device that displays and controls the status of a machine tool having a mounting unit to which a tool can be attached, a numerical control unit that controls movement of the mounting unit and the rotational speed of the tool in accordance with a machining program, and a vibration detection unit that detects vibrations of the tool. The display control device includes a display control unit that controls the display of time-series data indicating changes in vibration level detected by the vibration detection unit and changes in the rotational speed of the tool. When an instruction to change the rotational speed is received, the display control unit controls the display so that a marker indicating the change instruction is superimposed on the time-series data.

[0007] Another aspect of the present invention is a machine tool. The machine tool includes an input unit that accepts an operator's operation input, a mounting unit to which a tool can be attached, a numerical control unit that controls movement of the mounting unit and the rotational speed of the tool in accordance with a machining program, a vibration detection unit that detects vibration of the tool, and a display control unit that controls the display of time-series data showing changes in vibration level detected by the vibration detection unit and changes in the rotational speed of the tool. When an instruction to change the rotational speed is received from the input unit, the display control unit displays a marker indicating the time of the change instruction superimposed on the time-series data. [Effects of the Invention]

[0008] According to the present invention, when using a machine tool, a display can be provided to assist the operator in taking measures against chatter vibration. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a perspective view illustrating a schematic configuration of a machine tool according to an embodiment. [Figure 2] FIG. 2 is a diagram schematically illustrating an electrical configuration of a functional section related to the detection of chatter vibrations. [Figure 3] FIG. 2 is a functional block diagram of a control unit. [Figure 4] FIG. 10 is a diagram illustrating a management screen for managing the control state of the control device. [Figure 5] 10A and 10B are diagrams illustrating a tuning screen and a status screen. [Figure 6] FIG. 10 is a diagram illustrating a status screen switching screen. [Figure 7] 10A to 10C are diagrams illustrating examples of screens that may be displayed during the vibration control process. [Figure 8] 10A to 10C are diagrams illustrating examples of screens that may be displayed during the vibration control process. [Figure 9] 10 is a flowchart illustrating a vibration control process. [Figure 10] 10 is a flowchart showing a spindle rotation speed adjustment process in S22 of FIG. 9. [Figure 11] 10A and 10B are diagrams illustrating an example of a status screen that may be displayed during the vibration control process. [Figure 12] FIG. 10 is a diagram illustrating a status screen according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 is a perspective view showing a schematic configuration of a machine tool according to an embodiment. Here, the left-right, up-down, and front-rear directions when looking at the machine tool 1 from the front are defined as the X-axis, Y-axis, and Z-axis directions, respectively.

[0011] The machine tool 1 is a horizontal machining center and includes a processing device 2 and a control unit 4. A housing (not shown) is provided to cover the processing device 2, and a control panel is provided on the side of the housing. The control panel has a touch panel (described below) that can be operated by an operator.

[0012] The machining device 2 includes a bed 10, a column 12 erected on the bed 10, a spindle head 14 movably mounted on the front side of the column 12, and a table 16 movably mounted on the bed 10. The spindle head 14 has an axis in the Z-axis direction and supports a spindle 18 rotatably about that axis. The spindle head 14 is provided with a spindle motor for driving the spindle 18 to rotate. The spindle 18 functions as a "mounting portion" to which a tool T held in a tool holder 20 can be coaxially mounted. A workpiece W is fixed to the table 16 via a jig (not shown).

[0013] A guide rail 22 is provided on the front of the column 12, and a saddle 24 is supported thereon so as to be movable in the X-axis direction. A guide rail 26 is provided on the front of the saddle 24, and the spindle head 14 is supported thereon so as to be movable in the Y-axis direction. The movement of the saddle 24 and the spindle head 14 is achieved by a feed mechanism (not shown) and a servo motor that drives it. This feed mechanism is, for example, a screw feed mechanism using a ball screw. The spindle 18 is movable in the X-axis and Y-axis directions by driving the saddle 24 and the spindle head 14. An acceleration sensor 30 is built into the spindle head 14. The acceleration sensor 30 is used to detect chatter vibrations of the tool T, and details of this will be described later.

[0014] Meanwhile, a guide rail 32 is provided on the upper surface of the bed 10, and a saddle 34 is supported so as to be movable in the Z-axis direction. A table 16 is fixed on the saddle 34. The movement of the saddle 34 is achieved by a feed mechanism (not shown) and a servo motor that drives the feed mechanism. This feed mechanism is, for example, a screw feed mechanism using a ball screw. The workpiece W is movable in the Z-axis direction by driving the saddle 34. In other words, with the above configuration, the relative positions of the workpiece W and the tool T can be adjusted three-dimensionally.

[0015] FIG. 2 is a diagram showing a schematic diagram of the electrical configuration of a functional section related to the detection of chatter vibration. As described above, the spindle head 14 has a built-in acceleration sensor 30. The acceleration sensor 30 detects vibrations that occur in the tool T during machining of the workpiece W and outputs a signal corresponding to the vibrations. The acceleration detected by the acceleration sensor 30 (more specifically, an electrical signal representing the acceleration) is input to a signal processing device 40.

[0016] The signal processing device 40 is configured by mounting an A / D converter 42 and a frequency analyzer 44 on a dedicated board. The signal output from the acceleration sensor 30 is converted from analog to digital by the A / D converter 42, and then subjected to FFT (Fast Fourier Transform) by the frequency analyzer 44. This information is output to the control unit 4.

[0017] The control unit 4 includes a control device 50 and a vibration processing device 52. A display device 54 is connected to the control unit 4. The display device 54 is a touch panel provided on the operation panel, and displays a screen showing the control status of the machine tool 1 and an operation screen operated by the operator.

[0018] The vibration processing device 52 receives information indicating the control state from the control device 50, and outputs control commands according to operation inputs by the operator to the control device 50. The vibration processing device 52 executes predetermined processing related to chatter vibration based on signals received from the signal processing device 40 and the control device 50.

[0019] The vibration processing device 52 displays a screen (status screen) showing the vibration state of the spindle 18 (i.e., the vibration state of the tool T) based on the signal input from the signal processing device 40, and also determines whether chatter vibration is occurring. If the vibration processing device 52 determines that chatter vibration has occurred, it displays an operation screen (tuning screen) for converging the chatter vibration. These will be described in detail later.

[0020] The control device 50 controls actuators such as motors in accordance with a machining program (NC program) that is manually or automatically generated. When turning the workpiece W, the control device 50 drives the servo motor via the drive circuit 56 to feed and drive the spindle head 14. The control device 50 also drives the spindle motor via the drive circuit 56 to rotate the spindle 18.

[0021] FIG. 3 is a functional block diagram of the control unit 4. Each component of the control unit 4 is realized by hardware including computing units such as a CPU (Central Processing Unit) and various computer processors, 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 composed of device drivers, an operating system, various application programs located at higher levels than these, and libraries that provide common functions to these programs. Each block described below represents a functional block, not a hardware configuration.

[0022] The control unit 4 includes a user interface processing unit 110, a data processing unit 112, a data storage unit 114, and a detection unit 116. The user interface processing unit 110 accepts operation input from an operator and is responsible for user interface-related processing such as image display and audio output. The data processing unit 112 executes various processes based on data acquired by the user interface processing unit 110, information detected by the detection unit 116, and data stored in the data storage unit 114. The data processing unit 112 also functions as an interface between the user interface processing unit 110, the detection unit 116, and the data storage unit 114. The data storage unit 114 stores various programs and setting data.

[0023] The user interface processing unit 110 includes an input unit 120 and an output unit 122. The input unit 120 accepts input from an operator via a hardware device such as a touch panel or a steering wheel. The input unit 120 includes a change accepting unit 124. The change accepting unit 124 accepts change instructions from the operator, such as changes to the rotation speed or feed rate of the spindle 18.

[0024] The output unit 122 provides various information to the operator by image display or audio output. The output unit 122 includes a display unit 126. The display unit 126 may display a panel (keyboard and machine operation panel) as an operation screen on the display device 54. The display unit 126 displays a status screen showing the state (control state and vibration state) of the spindle 18, and displays the above-mentioned tuning screen when chatter vibration occurs (described in detail later).

[0025] The detection unit 116 includes a vibration detection unit 130 and a rotational speed detection unit 132. The vibration detection unit 130 detects vibrations of the spindle 18 (i.e., vibrations of the tool T) based on the sensor output from the acceleration sensor 30, and also acquires information output from the signal processing device 40. The rotational speed detection unit 132 detects the rotational speed of the spindle 18 (i.e., the rotational speed of the tool T) based on the sensor output of a rotary encoder (not shown) attached to the spindle 18.

[0026] The data storage unit 114 includes an NC program storage unit 140, a tool data storage unit 142, and a display data storage unit 144. The NC program storage unit 140 stores machining programs (NC programs). The tool data storage unit 142 stores information (tool information) about the tool T used in the machine tool 1 in association with a tool ID. The tool information includes, for example, the type of tool, tool diameter, and number of teeth. The tool information also corresponds to the adjustable range of the spindle rotation speed by the vibration processing device 52 (hereinafter referred to as the "adjustment range"). The display data storage unit 144 stores various image data such as screen data to be displayed on the display unit 126, soft keys to be displayed on the screen, dialog boxes, etc.

[0027] The data processing unit 112 includes a numerical control unit 150, a tool information management unit 152, a vibration processing unit 154, a recommended rotation speed calculation unit 156, and a display control unit 158. The numerical control unit 150 includes the functions of the control device 50. The numerical control unit 150 controls the machining device 2 in accordance with a machining program stored in the data storage unit 114, based on a command input from the input unit 120.

[0028] The numerical control unit 150 also sequentially transmits information (control information) indicating the current control state of the control device 50 to the vibration processing unit 154. The numerical control unit 150 transmits, for example, a control command value for the spindle rotation speed (hereinafter also referred to as "control command spindle rotation speed").

[0029] The tool information management unit 152 manages the information (tool information) of the tool T stored in the tool data storage unit 142 in association with the tool ID.

[0030] The vibration processing unit 154 includes a chatter detection unit 160 as a function of the vibration processing device 52. The above-mentioned frequency analysis unit 44 receives signals continuously output from the acceleration sensor 30 and performs Fourier analysis (frequency analysis) on the signals at predetermined sampling intervals to calculate the frequency (referred to as the "vibration frequency") and magnitude (also referred to as the "vibration level") of vibrations occurring in the tool T. The chatter detection unit 160 acquires information on the vibration level and vibration frequency, and determines that chatter vibrations have occurred when the vibration level exceeds a predetermined threshold value.

[0031] In the present embodiment, the frequency analysis device 44 is provided in the signal processing device 40 (see FIG. 2) and is separated from the control unit 4. However, in a modified example, the function of the frequency analysis device 44 may be included in the vibration processing unit 154 as a "frequency analysis unit." Furthermore, the signal processing device 40 may be incorporated as a part of the control unit 4.

[0032] When chatter vibration occurs, the recommended rotational speed calculation unit 156 calculates a change destination of the spindle rotational speed (also referred to as "recommended rotational speed") that is appropriate for converging the chatter vibration. The recommended rotational speed can be calculated by, for example, the method described in JP 2018-176296 A.

[0033] Specifically, if the detected chatter vibration is regenerative chatter, the recommended rotational speed SS (recommended value) can be calculated using the following formula (1) based on the vibration frequency ω0 (chatter frequency) at that time and the number of teeth n of the tool T. SS=(60×ω0) / (n×k) (1) Here, k is an arbitrary integer of 1 or more.

[0034] This recommended rotational speed SS is the rotational speed corresponding to the kth stable pocket on the stability limit diagram. There is a possibility that chatter vibration can be eliminated by adjusting the spindle rotational speed to the recommended rotational speed SS. If the recommended rotational speed SS obtained by the above formula (1) when k is set to 2, for example, is within the stable region for the spindle rotational speed S0 when chatter vibration occurs, chatter vibration can be eliminated by changing the spindle rotational speed from S0 to SS.

[0035] The number of teeth n of the tool T can be acquired based on the tool ID of the currently used tool T. The tool information management unit 152 acquires the number of teeth n by referring to the tool data storage unit 142 based on the tool ID. The recommended rotational speed calculation unit 156 calculates, as recommended rotational speeds to be presented to the operator, a first recommended value that is higher than the current control command spindle rotational speed and a second recommended value that is lower than the current control command spindle rotational speed.

[0036] The display control unit 158 ​​controls the display by the display unit 126. The display control unit 158 ​​causes the display unit 126 to display a screen (such as a status screen) showing the control state by the control device 50 and a screen (such as a tuning screen) for monitoring the occurrence of chatter vibrations.

[0037] Vibration processing unit 154 , recommended rotation speed calculation unit 156 , display control unit 158 ​​, change acceptance unit 124 and display unit 126 function as a “display control device” that controls the display of the operating state of machine tool 1 .

[0038] Next, the process of detecting and suppressing chatter vibration will be described in detail. FIG. 4 is a diagram showing a management screen for managing the control state of the control device 50. As shown in FIG. On this management screen, the NC program currently being executed is displayed in the right area of ​​the screen. A status screen is displayed in the upper left area of ​​the screen, and a tuning screen is displayed in the lower left area of ​​the screen. These displays use data stored in the display data storage unit 144.

[0039] 5A and 5B are diagrams showing a tuning screen and a status screen, where Fig. 5A shows an example of the tuning screen, and Fig. 5B shows an example of the status screen.

[0040] As shown in FIG. 5(A), an override bar 180 for indicating the spindle rotation speed is displayed in the central area of ​​the tuning screen. The override bar 180 is a scale object (an object with a scale function) that extends to the left and right of the screen, and its center indicates the 100% position of the program-commanded spindle rotation speed. Here, the "program-commanded spindle rotation speed" is the spindle rotation speed specified by the machining program. The program-commanded spindle rotation speed will not change unless a new value is commanded in the program. The current control-commanded spindle rotation speed (2500 min in the illustrated example) is displayed above the override bar 180. -1 ) The control command spindle speed is the spindle speed commanded by the PLC.

[0041] When the tuning screen is started, the program command spindle rotation speed and the control command spindle rotation speed are equal, so the control command spindle rotation speed is displayed above the center of the override bar 180. If the spindle rotation speed is changed by the vibration processing device 52, the display position of the control command spindle rotation speed is changed according to the rate of change. As long as normal control is being performed, the actual spindle rotation speed detected by the rotary encoder described above (also referred to as the "actual spindle rotation speed") will approximately match the control command spindle rotation speed.

[0042] In the override bar 180, the right end indicates a position of 150% (i.e., +50%) of the programmed spindle speed, and the left end indicates a position of 50% (i.e., -50%) of the programmed spindle speed. In other words, the override bar 180 corresponds to a "percentage display" that indicates the percentage of change in the control command spindle speed relative to the current programmed spindle speed.

[0043] The upper area of ​​the tuning screen displays the currently detected vibration level and peak frequency. "Peak frequency" refers to the vibration frequency at which the vibration level is currently at its maximum. In the illustrated example, the vibration level is 68 (dB) and the peak frequency is 1152 (Hz). Furthermore, because this vibration level has determined that chatter vibrations are occurring, the text "Chatter Occurring" is displayed to notify this fact.

[0044] When chatter vibration is detected, the recommended rotation speed calculation unit 156 calculates two recommended rotation speeds (first recommended value and second recommended value) for converging the chatter vibration, as described above. The display control unit 158 ​​displays the two calculated recommended values ​​on the tuning screen. In the illustrated example, "2878 min" is displayed below the scale as the first recommended value. -1 " is displayed, and the second recommended value is "2466min -1 " is displayed.

[0045] In the override bar 180, at the point corresponding to the ratio to the program command spindle speed, a ▼ indicating the position of the control command spindle speed and its numerical value (2500 min -1 ) is displayed. Then, the ▲ that indicates the position of the first recommended value and its value (2878min -1 ) is displayed in the override bar 180 at the position corresponding to the percentage of the programmed spindle speed. Similarly, the arrow indicating the position of the second recommended value and its numerical value (2466 min -1 ) appears in the override bar 180 at the location corresponding to the percentage of the programmed spindle speed.

[0046] The numerical value (m / min) below the spindle rotation speed indicates the peripheral speed of the tool (m / min), which is calculated using the following formula (2). Peripheral speed [m / min] = Spindle rotation speed [min -1 ]×π×(Tool diameter [mm] / 1000)...(2) This "circumferential speed" is an indicator of the tool load.

[0047] However, as will be described later, either the first recommended value or the second recommended value can be selected by the operator in advance, and therefore recommended values ​​that are not eligible for selection are grayed out. This recommended value can be preset by switching between selection buttons 182a and 182b, which will be described later. A detailed description of this will be omitted.

[0048] The tuning screen is an operation screen with a touch panel function, and displays multiple buttons that can be selected by the operator. Slightly below the left and right ends of the override bar 180, selection buttons 182a and 182b are displayed for selecting the method for setting the recommended value. A reset button 184 and an adjustment button 186 are displayed in the lower area of ​​the tuning screen. The adjustment button 186 functions as an "instruction input unit" that accepts a speed change command for the spindle rotation speed. The reset button 184 functions as a "reset command input unit" that accepts a command to reset the control command spindle rotation speed to the program command spindle rotation speed.

[0049] However, whether the reset button 184 and the adjustment button 186 can be selected is determined during the processing by the vibration processing unit 154, and if they can be selected they are displayed normally (also called "active display"), and if they cannot be selected they are grayed out. The adjustment button 186 is displayed as active if the selected recommended value is within a preset adjustment range.

[0050] In the illustrated example, the first recommended value has been selected as a preset, and the selection button 182a is displayed as active. Chatter vibrations have occurred in this state, so the second recommended value is grayed out. Furthermore, since the selected first recommended value is within the adjustment range, the adjustment button 186 is displayed as active. By tapping (selecting) the adjustment button 186 in this state, the operator can adjust the control command spindle rotation speed (2500 min -1 ) recommended rotation speed (first recommended value: 2878 min -1 ) can be instructed to change it to

[0051] In this embodiment, as shown in the figure, the adjustment range of the spindle rotation speed is set to 50 to 150% (i.e., ±50%) of the program command spindle rotation speed, thereby preventing the rotation speed (control state) of the spindle 18 from suddenly changing unexpectedly by the operator.

[0052] In response to an input from an operator, the vibration processing unit 154 outputs an instruction to change the spindle rotation speed to the numerical control unit 150. Upon receiving this instruction to change, the numerical control unit 150 changes the control command value for the spindle rotation speed (i.e., the control command spindle rotation speed).

[0053] The status screen shown in Fig. 5(B) illustrates the results of changing the control command spindle rotation speed in response to the recommended rotation speed presented by the tuning screen in Fig. 5(A). This status screen is the initial setting status screen (first status screen). In the center of the status screen, a sampling screen 170 is displayed, with the horizontal axis representing elapsed time and the vertical axis representing vibration level and spindle rotation speed. The sampling screen 170 is a real-time chart that displays changes in vibration level and spindle rotation speed in real time. The solid line indicates changes in vibration level (dB), and the dotted line indicates changes in control command spindle rotation speed (min -1 The ▼ in the graph is a marker that indicates the timing of switching the control command spindle rotation speed in response to an operation input (change instruction) by the operator.

[0054] This status screen is also an operation screen with touch panel functionality, and the horizontal axis scale on the sampling screen 170 can be selected from either a pattern with a maximum of 10 minutes or a pattern with a maximum of 1 minute (60 seconds). In the example shown, the latter has been selected. "0 minutes" on the right edge of the screen is the current time, and to the left of that is displayed a continuous list of previous sampling history. The sampling screen 170 is displayed in real time by turning on the data collection button 172 in the upper left of the screen.

[0055] The display control unit 158 ​​controls the display of time-series data indicating changes in the vibration level detected by the vibration detection unit 130 and changes in the spindle rotation speed (i.e., the rotation speed of the tool T) as this status screen. When an instruction to change the spindle rotation speed is received through an operation input by the operator, the display control unit 158 ​​displays a marker ▼ indicating the timing of the instruction to change, superimposed on the time-series data.

[0056] In the example shown, the control command spindle speed is set to 2500 min-1 approximately 48 seconds before the machine tool starts idling. -1Machining of a specified block was started. Immediately after that, chatter vibration occurred, causing the vibration level to rise sharply to about 60 dB. Therefore, approximately 45 seconds earlier, the operator had followed the instructions on the tuning screen to set the control command spindle speed to 2500 min -1 Approximately 2878 min -1 As a result, the chatter vibration subsided approximately 40 seconds ago, and machining continued with the vibration level reduced to about 40 dB. Machining of the block in question finished approximately 26 seconds ago.

[0057] 6A and 6B are diagrams showing the status screen switching screens, where Fig. 6A shows the second status screen and Fig. 6B shows the third status screen. In Fig. 6(A), dotted lines indicate block numbers of the machining program. The operator can switch the screen of Fig. 5(B) to the second status screen of this figure using a setting screen (not shown). The display control unit 158 ​​displays the block number, which is a parameter separate from the command spindle speed, as time-series data in response to a selection instruction input by the operator.

[0058] The second status screen allows the operator to grasp the block in which chatter vibration occurred and the control command spindle rotation speed was changed. In the example shown, chatter vibration occurred in the 50th block in the machining program, and it can be seen that the operator performed an operation input.

[0059] On this second status screen, the control command spindle speed itself that was on the first status screen is not displayed, but the change instruction timing (marker ▼) remains displayed. Therefore, by checking the second status screen, it is immediately clear in which block the control command spindle speed was switched by the operator.

[0060] In Figure 6(B), the dotted line indicates the peak frequency over time. The "peak frequency" refers to the vibration frequency that produces the highest vibration level at each point in time. Therefore, the peak frequency when chatter vibration occurs indicates the frequency of the chatter vibration itself (also called the "chatter frequency").

[0061] The operator can switch the screen of Fig. 5(B) or Fig. 6(A) to the third status screen of this figure using a setting screen (such as a pull-down menu) not shown. In response to a selection instruction input by the operator, the display control unit 158 ​​displays the peak frequency, which is yet another parameter, as time-series data.

[0062] The third status screen makes it possible to grasp the peak frequency immediately before the operator switches the control command spindle rotation speed when chatter vibration occurs, i.e., the frequency that is causing chatter vibration. In the example shown, it can be confirmed that the chatter frequency is approximately 1200 Hz.

[0063] Although the control command spindle rotation speed itself, which was present on the first status screen, is not displayed on this third status screen, the display of the change instruction timing (marker ▼) remains. Therefore, by checking the third status screen, it is possible to ascertain the peak frequency immediately before the operator switches the control command spindle rotation speed, in other words, when chatter vibration is occurring.

[0064] Time-series data including the vibration level, control command spindle rotation speed, change command timing (marker), block number, and peak frequency displayed on the first to third status screens described above is stored as control history data in the data storage unit 114. This allows the operator to check each status screen afterward.

[0065] 7 and 8 are diagrams showing examples of screens that may be displayed during the vibration control process. In this example, after the operator adjusts the control command spindle rotation speed twice, two markers ▼ indicating the timing of the change are superimposed on the time-series data on the status screen, as shown in Fig. 7. Because the chatter vibration did not converge even after these two adjustments, a third recommended rotation speed is presented on the tuning screen.

[0066] The operator changed the control command spindle rotation speed in accordance with this third suggestion, and three markers ▼ indicating the timing of the change were superimposed on the time-series data on the status screen, as shown in Fig. 8. Because the chatter vibration did not converge even after these three adjustments, a fourth recommended rotation speed was suggested on the tuning screen.

[0067] In this way, when the control command spindle rotation speed is switched multiple times, the recommended rotation speed displayed on the tuning screen changes each time. Furthermore, changes in vibration level due to input operations by the operator and the change history of the control command spindle rotation speed are updated moment by moment on the status screen.

[0068] Next, a specific process for suppressing chatter vibration will be described. Fig. 9 is a flowchart showing the vibration control process. Fig. 10 is a flowchart showing the spindle rotation speed adjustment process in S22 of Fig. 9. Fig. 11 is a diagram showing an example of a status screen that can be displayed during the vibration control process.

[0069] 9, in the vibration control process, the vibration processing unit 154 acquires vibration data of the main shaft 18 via the detection unit 116 (S10). The display control unit 158 ​​updates the status screen and tuning screen based on the vibration data (S12).

[0070] The status screen and tuning screen are displayed even while chatter vibration is not occurring. When the vibration level exceeds the threshold and chatter detection unit 160 detects chatter vibration (Y in S14), recommended rotation speed calculation unit 156 calculates a recommended rotation speed (S16). Then, a recommended value presentation process is executed (S18).

[0071] In this recommended value presentation process, if both the calculated first recommended value and second recommended value are within the adjustment range (in this embodiment, within ±50% of the program command spindle rotation speed), the display control unit 158 ​​displays both recommended values ​​(see FIG. 5(A)). In this case, when the operator taps (selects) the adjustment button 186, the control command spindle rotation speed is changed to the first recommended value.

[0072] On the other hand, if only the recommended value on the selected side (recommended selected value) is within the adjustment range, the display control unit 158 ​​displays only that recommended selected value and enables the adjustment button 186. In this case as well, when the operator taps the adjustment button 186, the control command spindle rotation speed is changed to the first recommended value.

[0073] If only the recommended value on the unselected side (recommended non-selected value) is within the adjustment range, the display control unit 158 ​​displays only the recommended non-selected value, but disables the adjustment button 186. That is, in this state, the operator cannot change the spindle rotation speed. However, by switching between the selection buttons 182a and 182b and changing the recommended selected value, the spindle rotation speed can be changed.

[0074] If neither the first recommended value nor the second recommended value is within the adjustment range, the display control unit 158 ​​hides both recommended values ​​and disables the adjustment button 186. In this state, the operator cannot change the spindle rotation speed.

[0075] When the adjustment button 186 is tapped by the operator (Y in S20), the spindle rotation speed adjustment process is executed (S22).

[0076] As shown in FIG. 10, in the spindle rotation speed adjustment process, the vibration processing unit 154 outputs an instruction to change to the selected recommended rotation speed (S62). The numerical control unit 150 changes the control command spindle rotation speed to the recommended rotation speed and controls the spindle 18. The display control unit 158 ​​updates the status screen and tuning screen (S63). At this time, a ▼ indicating the timing of switching the control command spindle rotation speed is added to the status screen, and the display position of the control command spindle rotation speed is updated on the tuning screen. In addition, the reset button 184 is enabled, allowing the operator to reset the control at any time. The reset button 184 is enabled when the program command spindle rotation speed and the control command spindle rotation speed differ.

[0077] The vibration processing unit 154 acquires vibration data of the spindle 18 via the detection unit 116 (S64). At this time, if a predetermined termination condition is not met (N in S66), the recommended rotation speed calculation unit 156 recalculates the recommended rotation speed (S68). In this embodiment, the "termination conditions" are set to be that the chatter vibration has converged, that the chatter vibration has become larger than before adjustment, that the type of chatter vibration has changed, or that the frequency of chatter vibration has changed. In a modified example, any one of these conditions, but not all of them, may be set as the termination condition. The display control unit 158 ​​keeps the stop button 187 displayed during this recalculation.

[0078] If the calculated recommended value is within the adjustment range (Y in S70), the process returns to S62. If the termination condition is thus met (Y in S66), the processes of S68 and S70 are skipped. The display control unit 158 ​​hides the recommended value (S72) and disables the adjustment button 186 by graying it out (S74). On the other hand, if the calculated recommended value is not within the adjustment range (N in S70), the display control unit 158 ​​also hides the recommended value (S72) and disables the adjustment button 186 by graying it out (S74).

[0079] Returning to Fig. 9, if adjustment button 186 is not tapped (N in S20), the process of S22 is skipped. If chatter vibration is not detected (N in S14), the processes of S16 to S22 are skipped. Then, if the system is shut down (Y in S24), such as when operation of machine tool 1 is stopped, the series of processes ends. If the system is not shut down (N in S24), the process returns to S10.

[0080] If the time series data shown in Figure 11 is obtained through the above processing process, the vibration level will show similar behavior in the first and second halves, but since the marker ▼ is only displayed in the second half, it can be seen that operator involvement is only recognized in the second half. In other words, it can be seen that the former is a result based on commands from the machining program, and the latter is a result based on commands input by the operator.

[0081] The machine tool 1 has been described above based on the embodiment. According to this embodiment, information for dealing with chatter vibration, that is, changes in spindle rotation speed and the timing of those changes, and the program locations corresponding to those change timings, are automatically recorded on the machine tool 1 side and displayed in a superimposed manner. This reduces the workload of the operator while the machine tool 1 is in operation. By having the machine tool 1 constantly record time-series data, it is possible to present to the operator completely synchronized data such as the timing of changes in the control command spindle rotation speed, the content of the changes, and the control state at the time of the changes.

[0082] By superimposing the machining conditions (spindle rotation speed) on the time-series data of vibration levels, it is possible to easily check the machining conditions that have been changed. In addition, when the spindle rotation speed is changed multiple times, it becomes easy to check the machining conditions that are most effective in suppressing chatter vibration.

[0083] Furthermore, by superimposing the change points (markers) of the machining conditions (spindle rotation speed) and the peak frequency on the time-series data of the vibration level, the chatter frequency can be easily identified. By combining this with the technology described in Patent Document 1, it is also possible to identify the location where chatter vibration occurs. Therefore, even if chatter vibration cannot be contained by simply changing the control command spindle rotation speed, it becomes easy to determine whether to change the tool, tool holder, or workpiece fixing method.

[0084] Furthermore, by superimposing the change points (markers) of machining conditions (spindle speed) and program block numbers on the time-series data of vibration levels, it is easy to identify program locations. It is also easy to identify locations within a block where chatter vibration is particularly large. Even if the spindle speed display is turned off, the change points can be easily identified by displaying the markers.

[0085] Furthermore, when chatter vibration occurs, a recommended change value (recommended rotation speed) to the control command spindle rotation speed to converge the chatter vibration is calculated internally in the machine tool, and the operator only needs to decide whether to approve it, making it easy to take a quick response. Even an operator with little experience and poor intuition can easily respond. According to this embodiment, a user-friendly display screen can be provided to the operator to prompt them to perform operations to suppress chatter vibration in the machine tool 1.

[0086] [Variations]

[0087] FIG. 12 is a diagram showing a status screen according to a modified example. In this modified example, the status screen includes a sampling screen 170 and a change application screen 190 that displays changes to the machining conditions as numerical values. The display control unit 158 ​​displays this change application screen 190 based on an operation by the operator. In the illustrated example, the operator has adjusted the control command spindle rotation speed four times, and four markers ▼ indicating the change timings are superimposed on the time-series data.

[0088] The total number of adjustments, adjustment number, changes to the spindle rotation speed, changes to the feed rate, program name, and program line (block number) are displayed on the change application screen 190. Here, the "total number of adjustments" indicates the number of times the control command value was changed to converge chatter vibration.

[0089] The "adjustment number" is the number of the adjustment that the operator wishes to check, and can be selected arbitrarily if the spindle rotation speed has been changed multiple times. In the illustrated example, any of the numbers 1 to 4 indicated by the four markers ▼ can be entered. That is, the display control unit 158 ​​displays the markers as input objects that accept the operator's selection input, and when any of the markers is selected, the change application screen 190 displays the changes corresponding to the selected marker. The operator can specify the adjustment number by increasing or decreasing it using the + button or - button. In this example, the first adjustment number has been selected, so the corresponding marker is displayed as active, and the other markers are grayed out.

[0090] As a result, in the first adjustment, the control command spindle rotation speed was 2458 min -1 From 2558 min -1 It shows that the feed rate was changed from 880 mm / min to 1013 mm / min, and that this change was made in block number 10. In the example shown in this diagram, the chatter vibration did not converge with the first adjustment, but did converge with the fourth adjustment. Therefore, by specifying the fourth adjustment number, it is possible to confirm the command spindle speed at which the chatter vibration converged.

[0091] According to this modification, by displaying the change application screen 190 after machining, the machining conditions applied when chatter vibration occurred and the change in vibration can be clearly confirmed afterwards as numerical values.

[0092] In the above embodiment, the control command spindle rotation speed is used as an example of the control command value, but a command value for the feed speed of the spindle (command feed speed) may also be included in the time-series data in addition to or instead of this. This makes it possible to determine whether the spindle rotation speed or the spindle feed speed is the main cause of chatter vibration.

[0093] In the above embodiment, an example has been shown in which the second and third status screens display other parameters such as block numbers and peak frequencies in the time-series data while turning off the display of the command spindle rotation speed. In a modified example, the display of the control command spindle rotation speed may be maintained while other parameters are superimposed.

[0094] In the above embodiment, an example was shown in which the adjustment range of the spindle rotation speed is set to a range of 50 to 150% (i.e., ±50%) of the control command spindle rotation speed, as shown in Fig. 8. In a modified example, the adjustment range can be set or changed at the discretion of the operator.

[0095] For example, the adjustment range can be set to 50 to 150% (i.e., ±50%), or alternatively, the adjustment range can be set to 80 to 120% (i.e., ±20%). Also, the adjustable percentage (%) can be set differently on the plus and minus sides of the control command spindle rotation speed. For example, the adjustment range can be set appropriately, such as by increasing the minus side, which is relatively safe. These settings can be made by switching the tuning screen to the setting screen. This setting allows the operator to set the upper and lower limits of the adjustment range at their discretion, enabling operation tailored to the individual operator's intuition.

[0096] In the above embodiment, an example has been shown in which a tuning screen is displayed and a recommended change in spindle rotation speed is calculated internally in the machine tool when chatter vibration occurs. In a modified example, the operator may change the value based on his or her own intuition. In such a case, the tuning screen may be omitted. Specifically, this applies to a case in which the operator manually operates an override switch provided on the operation panel of the machine tool to change the control command value. In such a case, information on how to deal with chatter vibration is automatically recorded on the machine tool side and displayed superimposed, allowing the operator to reflect this information in future chatter vibration countermeasures.

[0097] In the above embodiment, an example was shown in which the current control command spindle rotation speed is displayed above the override bar 180. In a modified example, the actual spindle rotation speed may be displayed instead. This is because the current control command spindle rotation speed is approximately equal to the actual spindle rotation speed. In this case, the "actual spindle rotation speed" corresponds to the "second rotation speed." The recommended rotation speed calculation unit 156 calculates a first recommended value higher than the actual spindle rotation speed and a second recommended value lower than the actual spindle rotation speed as recommended rotation speeds to be presented to the operator.

[0098] In the above embodiment, a horizontal machining center is exemplified as the machine tool 1. In a modified example, it may be a vertical machining center. Alternatively, it may be a turning sensor, or it may be a multi-tasking machine that has the functions of both a machining center and a turning center. The display control for suppressing chatter vibration described above may be applied to these machine tools.

[0099] 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]

[0100] 1 machine tool, 2 machining device, 4 control unit, 12 column, 14 spindle head, 16 table, 18 spindle, 20 tool holder, 30 acceleration sensor, 40 signal processing device, 44 FFT, 50 control device, 52 vibration processing device, 54 display device, 110 user interface processing unit, 112 data processing unit, 114 data storage unit, 116 detection unit, 120 input unit, 122 output unit, 124 change acceptance unit, 126 display unit, 130 vibration detection unit, 132 rotational speed detection unit, 150 numerical control unit, 152 tool information management unit, 154 vibration processing unit, 156 recommended rotational speed calculation unit, 158 display control unit, 160 chatter detection unit, 170 sampling screen, 172 data collection button, 180 override bar, 186 adjustment button, 190 change application screen, T tool, W workpiece.

Claims

1. A display control device that displays and controls the state of a machine tool having: (i) a mounting unit to which a tool can be attached; (ii) a numerical control unit that controls movement of the mounting unit and a rotational speed of the tool in accordance with a machining program; and (iii) a vibration detection unit that detects vibration of the tool, a change receiving unit that receives a change instruction to change the rotation speed from the rotation speed when the vibration level detected by the vibration detecting unit exceeds a predetermined value; a display control unit that controls the display of (i) an image of time-series data showing a change in vibration level detected by the vibration detection unit and a change in the rotation speed of the tool, and (ii) an image including rotation speed information for changing the rotation speed of the tool, A display control device that changes the display of the image of the time-series data and the image including the rotational speed information in accordance with a change in the vibration level caused by control based on the change instruction received by the change receiving unit.

2. a mounting portion to which a tool can be attached; a numerical control unit that controls the movement of the attachment unit and the rotation speed of the tool in accordance with a machining program; a vibration detection unit that detects vibrations of the tool; a change receiving unit that receives a change instruction to change the rotation speed from the rotation speed when the vibration level detected by the vibration detecting unit exceeds a predetermined value; a display control unit that controls the display of (i) an image of time-series data showing a change in vibration level detected by the vibration detection unit and a change in the rotation speed of the tool, and (ii) an image including rotation speed information for changing the rotation speed of the tool, The machine tool changes the display of the image of the time-series data and the image including the rotational speed information in accordance with a change in the vibration level caused by control based on the change instruction received by the change receiving unit.

3. A display control program for displaying and controlling the state of a machine tool having: (i) a mounting portion to which a tool can be attached; (ii) a numerical control portion that controls movement of the mounting portion and a rotational speed of the tool in accordance with a machining program; and (iii) a vibration detection portion that detects vibration of the tool, a change receiving means for receiving a change instruction to change the rotation speed from the rotation speed when the vibration level detected by the vibration detection unit exceeds a predetermined value; a display control means for controlling the display of (i) an image of time-series data showing a change in vibration level detected by the vibration detection unit and a change in the rotation speed of the tool, and (ii) an image including rotation speed information for changing the rotation speed of the tool, a display control program that changes the display of the image of the time-series data and the image including the rotational speed information in accordance with a change in the vibration level caused by control based on the change instruction received by the change receiving means;

4. A display method for displaying and controlling a state of a machine tool having (i) a mounting portion to which a tool can be attached, (ii) a numerical control portion that controls movement of the mounting portion and a rotational speed of the tool in accordance with a machining program, and (iii) a vibration detection portion that detects vibration of the tool, comprising: a change receiving step of receiving a change instruction to change the rotation speed from the rotation speed when the vibration level detected by the vibration detection unit exceeded a predetermined value; a display control step of controlling the display of (i) an image of time-series data showing a change in vibration level detected by the vibration detection unit and a change in the rotation speed of the tool, and (ii) an image including rotation speed information for changing the rotation speed of the tool, A display method for changing the display of the image of the time-series data and the image including the rotational speed information in accordance with a change in the vibration level caused by control based on the change instruction received in the change receiving step.

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