Vibration information display device for a machine tool

Abstract

Vibration information display device (10) for a machine tool in which a tool or a workpiece is rotated to machine the workpiece, wherein the vibration information display device (10) is arranged in the machine tool which has a vibration detection system configured to detect chatter vibrations occurring during machining, wherein the vibration information display device (10) comprises: a monitor (19) configured to display information about the chatter vibrations; a vibration information acquisition unit configured to acquire vibration information when chatter vibrations are detected; a work information acquisition unit that is configured to acquire work information from the machine tool when chatter vibrations are detected; a storage unit (15) that stores the acquired vibration information and work information; a display control unit (18) configured to display the vibration information and work information stored in the memory unit (15) on the monitor (19), or alternatively, the display control unit (18) configured to display the vibration information stored in the memory unit (15) together with trajectory information of a cutting edge of the tool contained in the work information on the monitor (19); a vibration limitation function that is configured to ensure a limitation of the detected chatter vibrations, wherein the display control unit (18) is configured to display the vibration information together with an achieved state of the vibration limitation function on the monitor (19); and an input unit to the monitor (19), wherein When the input unit is operated, the display control unit (18) is configured to display a screen regarding countermeasures to limit the chatter vibrations, wherein In order to display the vibration information together with the trajectory information of the cutting edge of the tool on the monitor (19), the display control unit (18) is configured to display a position of the chatter vibrations on a trajectory of the cutting edge of the tool, and, when the position is selected with the input unit, the display control unit (18) is configured to display the screen regarding countermeasures to limit the chatter vibrations at the position selected on the monitor (19), wherein the display control unit (18) is configured to ensure change information required to generate the screen with the input unit.

Description

[0001] The invention relates to a vibration information display device for displaying information about chatter vibrations in a machine tool performing machining while the tool or workpiece is rotating. Chatter vibrations can cause deterioration of a machined surface and reduce tool life.

[0002] During machining, depending on a machining condition such as main spindle speed or feed rate, chatter vibrations occur, which may degrade the machined surface. These chatter vibrations damage the tool, resulting in a reduction of tool life. The machining conditions for products are provisionally set at the beginning based on the last operation. An operator confirms the provisional machining settings to finalize the machining conditions. However, to save on production preparation costs, in the case of a long machining operation, such as for a molded part, the operator cannot wait to confirm the machining. In the case of such unattended operation of a machine, the procedure described in the publication of Japanese unexamined patent application No.2012-183596 (JP 2012-183596 A) disclosed technique used to ensure the limitation of generated chatter by automatically changing the main spindle speed.

[0003] For example, the publication of unexamined Japanese patent application No. 2009-115481 (JP 2009-115481 A), the publication of unexamined Japanese patent application No. 10-328976 (JP 10-328976 A), and the publication of unexamined Japanese patent application No. 2012-81562 (JP 2012-81562 A) disclosed techniques for recording, analyzing, and reporting operating conditions, such as vibrations generated during machining and the presence / absence of an operation that, as described above, automatically changes the main spindle speed. JP 2009-115481 A discloses the plurality of vibration detection sensors, the monitoring diagnostic device, and the alarm notification means. The vibration detection sensors are installed at several locations where vibrations occur due to a rotating drive of the rotary machine. The monitoring and diagnostic device is coupled to the vibration detection sensors.The alarm notification device is linked to the monitoring diagnostics device, and when the monitoring diagnostics device diagnoses the condition as abnormal, the alarm notification device issues an alarm. An alarm value (oscillation level) is sent via email to an administrator or displayed as a message on an editing output screen that trains the alarm notification device.

[0004] JP 10-328976 A discloses the following technique. The NC device is located near or integrally with the machine tool. The NC device combines the machine tool's work information and time information into a log data record. The NC device stores the log data record daily as a log file for each day in the storage device. The NC device aggregates the log data record in the log file to store the aggregated result as an execution information file in the storage device. The NC device displays the log file and the execution information file data on the display device.JP 10-328976 A discloses that the log record contains data such as a date and time, tool numbers, comments, spindle speeds, feed rates, usage durations (e.g., a period (second) from one tool change instruction to the next tool change instruction), cutting periods (e.g., a period (second) during which a feed instruction, such as G01, G02, and G03, is in processing), and fast-feed periods (e.g., a period (second) during which a fast-feed instruction, such as G00, is in execution).

[0005] JP 2012-81562 A discloses the following machining history management device. The machining history management device stores a rotational shaft speed and a vibration acceleration in a frequency range as the machining history. Additionally, the machining history management device stores the machining history not only when the rotational shaft speed changes, but also when the maximum value of the vibration acceleration in the frequency range exceeds a predetermined threshold. Because the machining history management device records the change in rotational shaft speed in conjunction with the chatter vibration condition, an operator can monitor the rotational shaft speed in conjunction with the chatter vibration condition, which helps to effectively prevent chatter vibrations.

[0006] It was also known that the well-known method described in, for example, the non-patent literature 1 “2008, The Japan Society for Precision Engineering Spring Conference Academic Lecture Proceedings, ‘Inverse identification of a transfer function with experimental results in endmilling,’ Nagoya University, Yusuke Kurata, Norikazu Suzuki, Eiji Shamoto” uses the stored machining history to display the stability limit graph.

[0007] In the revelation in JP 2009-115481 A, an alarm is issued to the alarm notification device when the condition is diagnosed as abnormal. The vibration level at that time is sent to the administrator via email or displayed on the machining output screen, which is configured as the alarm notification device. However, with a machine tool that moves the tool and workpiece relative to each other during machining, it is necessary to determine the location of an abnormality on the workpiece and correct the program. For this, unlike rotary machine equipment, the machine tool also requires information about the position where the abnormality occurs, resulting in insufficient information.

[0008] In the revelation of JP 10-328976 A, the work information is recorded daily as a log file, and the data in the file is displayed. However, information about a machining abnormality must be extracted from the various parts of a work information file, which takes time for analysis. If the operator is not present during the machining process, it is unclear whether the chatter vibrations are occurring or not until the operator sees the work information file.

[0009] In the disclosure of JP 2012-81562 A, countermeasures against chatter vibrations, such as the stability limit graph, are presented using the stored work information. However, as in JP 10-328976 A, in the case where the operator is not present during the machining process, it is unclear whether the chatter vibrations occur or not until the operator sees the work information.

[0010] DE 10 2015 220 995 A1 relates to a system with a circuit designed to generate bounce information based on sensor data obtained from a machining operation performed on a machine with a previously selected tool speed setting. The bounce information includes a bounce degree value and a bounce frequency value. Several different potential tool speed settings are determined based on the bounce frequency value generated from the machining operation. The circuit generates a user interface that provides several different tool speed settings for selection by the user, including the previously selected tool speed setting and the several different potential tool speed settings.The user interface is designed to specify the bounce value for the previously selected tool speed setting.

[0011] US 2014 / 0180467A1 concerns a load indicator device for a machine tool. The load indicator device acquires machine coordinate values ​​and load values ​​for axes of the machine tool for each predetermined time from an axis control circuit that controls the machine tool.

[0012] Three-dimensional coordinate values ​​of a tool's center point are calculated to obtain a tool trajectory. This calculation is based on machine coordinate values ​​for the axes, recorded at each predetermined time, and information about the machine tool's configuration. When the tool trajectory is displayed on a screen, vectors of the load values ​​for the axes, stored for each predetermined time, are shown.

[0013] Therefore, it is an object of the invention to provide a vibration information display device for a machine tool that immediately displays information about chatter vibrations on a monitor and provides the information to the operator who is away from the machine immediately afterwards, in order to ensure notification of the process abnormality together with the work information.

[0014] To solve the problem described above, according to a first aspect of the invention, a vibration information display device is arranged in the machine tool that is machining a workpiece while a tool or workpiece is rotating. The machine tool has a vibration detection system configured to detect chatter vibrations occurring during machining. The vibration information display device includes a monitor that displays information about the chatter vibrations. Furthermore, the vibration information display device includes a vibration information acquisition unit, a work information acquisition unit, a storage unit, and a display control unit. The vibration information acquisition unit acquires vibration information when chatter vibrations are detected. The work information acquisition unit acquires work information for the machine tool when chatter vibrations are detected.The memory unit stores the acquired vibration and machining information. The display control unit shows the vibration and machining information stored in the memory unit on the monitor. Alternatively, the display control unit displays the vibration information stored in the memory unit along with trajectory information of a cutting edge of the tool, which is included in the machining information.

[0015] Furthermore, the vibration information display device has a vibration limitation function configured to ensure the limitation of detected chatter vibrations. The display control unit shows the vibration information along with the current status of the vibration limitation function on the monitor.

[0016] The vibration information display device also includes an input unit for the monitor. When the input unit is operated, the display control unit shows a screen with information on countermeasures to limit the chatter vibrations.

[0017] Furthermore, the display control unit shows the position of chatter vibrations along a trajectory of the tool's cutting edge, displaying the vibration information along with the cutting edge trajectory information on the monitor. When the position is selected using the input unit, the display control unit shows the screen with information on countermeasures to limit the chatter vibrations at the selected position on the monitor. The display control unit ensures the necessary switching information to generate the screen with the input unit.

[0018] According to a second aspect of the disclosure, the multiple positions of the chatter vibrations on the trajectory of the cutting edge of the tool are selectable from the first aspect using the input unit. When multiple positions are selected using the input unit, the monitor displays a screen regarding countermeasures to limit the chatter vibrations at all the selected positions.

[0019] In the disclosure according to the first aspect, the monitor immediately displays information about the chatter vibrations of the machine tool along with the operating information. Accordingly, any process abnormality occurring during unattended operation can be displayed to the operator immediately upon their return to the machine. In this case, the program in which the chatter vibrations occurred, the cutting edge position of the tool, or similar information can be recorded.

[0020] The disclosure relating to the vibration limitation function can also include whether the machine automatically performed an operation to limit the chatter vibrations or not.

[0021] In the disclosure relating to the input unit, the input operation displays information on countermeasures to limit the chatter vibrations. Accordingly, information on countermeasures against vibrations can be easily accessed, ensuring immediate action. Therefore, processing is quickly optimized.

[0022] In the disclosure regarding the display of the position of chatter vibrations on the trajectory of the tool's cutting edge, the operator can configure the information required to instantly generate the screen. Therefore, the operator can quickly implement countermeasures without prior preparation.

[0023] In the disclosure according to the second aspect, in addition to the effect of the first aspect, the operator can find the countermeasures that take into account all the reasons for chatter vibrations that occur due to different reasons depending on the mechanical properties and the change in the machining state. Fig. Figure 1 is a block configuration diagram of a vibration information display device. Fig. Figure 2 is a side view of a main spindle housing. Fig. Figure 3 is a front view (a bottom view) of the main spindle housing. Fig. Figure 4 is a flowchart for the acquisition control of work information, vibration information, or similar information. Fig. 5 is an explanatory view of acquired work information and vibration information. Fig. Figure 6 is an explanatory view of a display screen on a monitor. Fig. Figure 7 is an explanatory view of the display screen on the monitor for an edge-trajectory curve with chatter information. Fig. Figure 8 is an explanatory view of the monitor display screen showing a stability limit graph. Fig. Figure 9 is an explanatory view of a modification example of the monitor's display screen for the cutting edge trajectory curve with the chatter information. Fig. Figure 10 is an explanatory view of a modification example of the monitor display screen that shows the stability limit graph.

[0024] The following describes embodiments of the disclosure based on the drawings.

[0025] Fig. Figure 1 is a block configuration diagram that represents an example of a vibration information display device for a machine tool. Fig. Figure 2 is a side view of a main spindle housing of the machine tool. Fig. Figure 3 is a front view of the main spindle housing (a drawing showing the main spindle housing in an axial direction from a bottom).

[0026] Reference numeral 1 denotes a main spindle housing containing a main spindle 3 in a machine tool. The main spindle housing 1 rotates a tool held on the main spindle 3 to machine a workpiece placed on the table below. The main spindle housing 1 contains vibration sensors 2a to 2c, which are accelerometers. The vibration sensors 2a to 2c are used to detect vibrations (oscillations along a time axis) generated in the main spindle 3, which is rotatable about a C-axis, over a specific time period. To detect vibration information in one direction perpendicular to another, the vibration sensors 2a to 2c are mounted in the main spindle housing 1 in a configuration such that vibration information is detectable in the time period along the X-axis, Y-axis, and Z-axis directions, all of which are perpendicular to each other.

[0027] A vibration information display device 10 includes an FFT calculation device 11 and an NC device 12. The FFT calculation device 11 performs a Fourier analysis based on a vibration acceleration detected by the vibration sensors 2a to 2c.

[0028] The NC device 12 includes a vibration detection unit 13 as a means of obtaining vibration information. The vibration detection unit 13 compares a vibration value (a maximum acceleration) at which the Fourier analysis was performed by the FFT calculation unit 11 and a threshold value set by an operator to determine whether or not chatter vibrations are occurring. If the vibration detection unit 13 determines that the vibration value is above the threshold value and a vibration change rate exceeds the set value, the vibration frequency is transmitted to an optimal speed calculation unit 14. The optimal speed calculation unit 14 calculates an optimum main spindle speed to limit the chatter vibrations using the well-known technique disclosed in JP 2012-183596 A and automatically modifies the main spindle speed.Calculating the optimal rotational speed requires knowing the number of cutting edges Z of the tool. The operator enters the number of cutting edges Z in advance.

[0029] If the vibration value exceeds the threshold and the vibration rate of change exceeds the set value, the vibration detection unit 13 instructs a storage unit 15, which is a storage device, to store the vibration value. Additionally, the vibration detection unit 13 instructs the machine operation control unit 16 to transfer the machine's operating information to the storage unit 15 as an operating information acquisition device. This operating information includes a time, a program name, a program execution code, a cutting edge position, a tool number, a main spindle speed, a feed rate, a workpiece zero point, a tool length, a machining coordinate, or similar information. The machine operation control unit 16 obtains the program name and the execution code from a program translation unit 17, into which the program is entered by the operator.The machine operation control unit 16 monitors a detector or similar device arranged on the machine tool to obtain the main spindle speed, the feed rate, path information of the cutting edge of the tool, or similar information.

[0030] Thus, the storage unit 15 stores the operating information along with the vibration value. A display control unit 18 then directs a monitor 19 to display the vibration information. The NC unit 12 is equipped with a monitor 19 as standard to display an NC program, the current position of the machine, or similar information. The vibration information is also stored in an external memory 20. The display control unit 18 also ensures that the vibration information is displayed on the monitor 19 along with the path of the cutting edge of the tool. Upon request from the operator, the display control unit 18 also displays the result of the optimal speed calculation, which is calculated using the vibration information by the optimal speed calculation unit 14.

[0031] The following describes, with reference to the flowchart in Fig. 4, a procedure to display the vibration information on the monitor 19 in the vibration information display device 10 configured as above.

[0032] First, the machine operation determination unit 16 obtains a current main spindle speed, and the FFT calculation unit 11 obtains a current vibration value (S11). Next, the vibration determination unit 13 compares a threshold value preset by the operator with the vibrations obtained by the FFT calculation unit 11 (S12). If the detected vibration is less than the threshold value, the program step returns to S11. If the detected vibration in S12 is greater than the threshold value, a vibration change rate per preset time unit is monitored. That is, the machine operation determination unit 16 determines whether the vibration change rate exceeds the preset value or not. If the vibration change rate does not exceed the preset value, the machine operation determination unit 16 waits for the vibration change rate (S13) to exceed it.If the vibration change rate exceeds the set value, the vibration value at that time and an achieved state of a vibration limitation function (presence / absence of a change to the optimal speed by the optimal speed calculation unit 14 and a result when changed to the optimal speed) are added to the machine's operating information, and the storage unit 15 stores the operating information (S14).

[0033] As a result, as in Fig. Figure 5 shows how a saved data record is generated. A saved data record contains the time, program name, program execution code, tool cutting edge position, tool number, main spindle speed, vibration value, or similar data. As shown in Fig. As shown in Figure 6, the display control unit 18 generates a new window in the foreground of the monitor 19 screen to display data content. This window remains displayed until an "OK" button is pressed on the monitor 19, which is a touch panel (input device) (even if the machine is switched off and then switched on again).

[0034] Here, the display control unit 18 generates a stability limit graph by pressing a "countermeasures" button, which is displayed in Fig. Figure 8 shows a screen displaying countermeasures for limiting chatter vibrations using techniques such as those disclosed in non-patent literature 1 (disclosing the method of performing a reverse identification of the chatter vibration frequency to identify the modal parameter). At this point, settings for information required to generate the stability limit graph, such as the number of cutting edges, can be entered on this screen. This ensures that the stability limit graph is displayed without presetting the individual items. Accordingly, the operator can determine whether a stability limit is high at the current rotational speed.This allows the operator to easily learn about countermeasures that are effective in limiting chatter vibrations (whether the speed should be changed to one on the high-speed side, where the stability limit is large, or on the low-speed side).

[0035] Meanwhile, the monitor can be set to 19, as in Fig. Figure 7 shows the trajectory of the cutting edge of the tool to which a stored data set is associated, instead of the one shown in Figure 7. Fig. The display shown in Figure 6 shows the presence / absence of chatter and the presence / absence of an operation to limit the chatter, indicated by symbols and arranged on the trajectory. Therefore, when the operator selects a respective symbol and presses the "Countermeasures" button (an input device), the stability limit graph for the selected machined area is displayed, as shown in Figure 6. Fig. Figure 8 is shown. This allows the operator to simultaneously learn about the countermeasures that are effective in limiting the chatter vibrations.

[0036] However, in a case where there are two machined areas at distant positions, a display example of the trajectory of the cutting edge of the tool is shown as in Fig. Figure 9 shows the chatter vibrations occurring at position 1 and position 2. Since the machining positions are different, the mechanical properties change, and therefore the stability limit graphs can differ between position 1 and position 2. However, there may be a case, such as machining with an identical tool, where it is desirable for the machining conditions to be identical at both points. Accordingly, the countermeasures at all selected points are fully displayed here to address the issue described in Figure 1. Fig. The stability limit graph shown in Figure 10 adds the countermeasures against the respective chatter oscillations at points 1 and 2 and is more complex than the stability limit graph in Figure 10. Fig. 8 is to display.

[0037] Thus, according to the embodiment, the vibration information display device 10 comprises the vibration detection unit 13, the machine operation detection unit 16, the storage unit 15, and the display control unit 18. The vibration detection unit 13 is configured to obtain vibration information when chatter vibrations are detected. The machine operation detection unit 16 obtains the machining information of the machine tool when chatter vibrations are detected. The storage unit 15 stores the obtained vibration information and operating information. The display control unit 18 displays the vibration information and operating information stored in the storage unit 15, along with the achieved state of the vibration limitation function, on the monitor 19.Alternatively, the display control unit 18 displays the vibration information stored in the memory unit 15, along with the achieved state of the vibration limitation function and the trajectory information of the tool's cutting edge, contained in the work information, on the monitor 19. This ensures that information about chatter vibrations of the machine tool is displayed immediately on the monitor 19, together with the work information. Accordingly, any machining abnormality that occurred during an unattended operation can be displayed to the operator returning to the machine immediately afterward. In this case, information such as the program in which the chatter vibration occurred, the cutting edge position of the tool, and whether or not the machine automatically performed an operation to limit the chatter vibrations, can be recorded.

[0038] Specifically, the display control unit 18, when the "Countermeasures" button on the monitor 19 is touched, shows the stability limit graph with regard to countermeasures for limiting chatter vibrations. Accordingly, information about countermeasures against vibrations can be easily obtained, ensuring immediate action. Therefore, processing is quickly optimized.

[0039] To display the vibration information on monitor 19, along with the achieved state of the vibration limitation function and the trajectory information of the tool's cutting edge, the display control unit 18 shows the position of the chatter vibrations on the cutting edge trajectory of the tool. When a selection action is performed on the position, the display control unit 18 displays the stability limit graph on monitor 19, showing countermeasures for limiting the chatter vibrations at the selected positions. The display control unit 18 modifies information required to generate the stability limit graph on monitor 19, such as the number of cutting edges. Accordingly, the operator can input the information required to generate the stability limit graph immediately. Therefore, the operator can quickly access the countermeasures without prior preparation.

[0040] Furthermore, multiple positions of the chatter vibrations on the trajectory of the tool's cutting edge can be selected on monitor 18. If a selection operation is performed at multiple positions, monitor 19 displays the stability limit graph with regard to countermeasures to limit the chatter vibrations at all selected positions. Therefore, the operator can identify countermeasures that address all causes of chatter vibrations, which can arise for various reasons depending on the mechanical properties and changes in the machining condition.

[0041] The embodiment uses vibration sensors as a means of detecting vibrations. However, a microphone, a position / rotation detector, and the current from a main spindle / feed axis motor can also be used. Although the embodiment determines chatter vibrations by comparing both the vibration threshold and the set vibration rate, the chatter vibrations can only be compared to the threshold. Even with a machine tool lacking a vibration limitation function, displaying the vibration information, the working information, and the cutting edge path information of the tool ensures immediate notification of a process abnormality.

[0042] Furthermore, the work information acquisition method can be configured as follows. In addition to the machine operation determination unit within the NC device, the work information is output, for example, via a network connected to an external memory and the NC device to an external arithmetic unit. The machining status is then analyzed, and the analysis result is transmitted to the NC device via the network.

[0043] It is explicitly stated that all features disclosed in the description and / or the claims are intended to be disclosed separately and independently of one another, irrespective of the combination of features in the embodiments and / or the claims, for the purpose of original disclosure and for the purpose of limiting the claimed invention. It is explicitly stated that all ranges of values ​​or indications of groups of units disclose any possible intermediate value or unit for the purpose of original disclosure and for the purpose of limiting the claimed invention, in particular as limits of ranges of values.

Claims

[1] Vibration information display device (10) for a machine tool in which a tool or a workpiece is rotated to machine the workpiece, wherein the vibration information display device (10) is arranged in the machine tool which has a vibration detection system configured to detect chatter vibrations occurring during machining, wherein the vibration information display device (10) comprises: a monitor (19) configured to display information about the chatter vibrations; a vibration information acquisition unit configured to acquire vibration information when chatter vibrations are detected; a work information acquisition unit that is configured to acquire work information from the machine tool when chatter vibrations are detected; a storage unit (15) that stores the acquired vibration information and work information; a display control unit (18) configured to display the vibration information and work information stored in the memory unit (15) on the monitor (19), or alternatively, the display control unit (18) configured to display the vibration information stored in the memory unit (15) together with trajectory information of a cutting edge of the tool contained in the work information on the monitor (19); a vibration limitation function that is configured to ensure a limitation of the detected chatter vibrations, wherein the display control unit (18) is configured to display the vibration information together with an achieved state of the vibration limitation function on the monitor (19); and an input unit to the monitor (19), wherein When the input unit is operated, the display control unit (18) is configured to display a screen regarding countermeasures to limit the chatter vibrations, wherein In order to display the vibration information together with the trajectory information of the cutting edge of the tool on the monitor (19), the display control unit (18) is configured to display a position of the chatter vibrations on a trajectory of the cutting edge of the tool, and, when the position is selected with the input unit, the display control unit (18) is configured to display the screen regarding countermeasures to limit the chatter vibrations at the position selected on the monitor (19), wherein the display control unit (18) is configured to ensure change information required to generate the screen with the input unit. [2] Vibration information display device (10) for a machine tool according to claim 1, wherein the positions of the chatter vibrations on the path of the cutting edge of the tool are configured such that several can be selected with the input unit, wherein, when a plurality of the positions are selected with the input unit, the monitor (19) is configured to display a screen regarding countermeasures to limit the chatter vibrations at all the selected positions.

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