Motor monitoring device

Abstract

A motor-monitoring device according to one embodiment of the present disclosure, which allows easy ascertaining of the status of a motor, comprises: a rotation speed acquisition unit that acquires the rotation speed of a motor operating according to an operating program; a history information storage unit that stores history information including the rotation speed at fixed time intervals; and a graph display unit that plots markers indicating the rotation speed in a graph region with one axis used for time and the other axis for rotation speed, the graph display unit changing the mode of the marker according to a prescribed index.

Description

Technical Field

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[0001] The present invention relates to a motor monitoring device.

Background Art

[0002] For example, in a motor whose load can change significantly, such as the spindle motor of a machine tool, if the high-load state continues, heat may accumulate and cause overheating. For such motors, various time ratings can be set to operate without overheating under specific conditions. Examples of time ratings include the continuous rating that can be continuously operated, the short-time rating that can be operated for a certain period of time (load time) from the state of room temperature, and the repetitive rating that can be operated for a certain period of time (load time ratio) within a predetermined cycle time, as defined in JIS-C4034-1.

[0003] It has also been proposed to estimate the time until the motor overheats when maintaining the current operating state (see, for example, Patent Document 1). If the time until overheating is known, it is possible to determine whether the current processing can be continued until the end.

Prior Art Documents

Patent Documents

[0006] A motor monitoring device according to one aspect of the present disclosure includes: a rotation speed acquisition unit that acquires the rotation speed of a motor operating according to an operating program; a history information storage unit that stores history information including the rotation speed at regular time intervals; and a graph display unit that plots a marker indicating the rotation speed on a graph region where one axis represents time and the other axis represents the rotation speed, wherein the graph display unit changes the appearance of the marker according to a predetermined index. [Effects of the Invention]

[0007] According to this disclosure, the motor's status can be easily determined. [Brief explanation of the drawing]

[0008] [Figure 1] This is a block diagram showing the configuration of a machine tool equipped with a motor monitoring device according to the first embodiment of this disclosure. [Figure 2] Figure 1 shows an example of the information stored by the history information storage unit of the motor monitoring device. [Figure 3] This figure illustrates the display shown by the motor monitoring device in Figure 1. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Figure 1 is a block diagram showing the configuration of a machine tool 1 equipped with a motor monitoring device according to the first embodiment of the present disclosure.

[0010] The machine tool 1 comprises a numerical control device 10 which is one embodiment of the motor monitoring device according to the present invention, a spindle motor 20, a rotation speed detector 21 which detects the rotation speed of the spindle motor 20, a current detector 22 which detects the current of the spindle motor 20, a temperature detector 23 which detects the winding temperature of the spindle motor 20, a display device 30 which displays information on the screen according to the numerical control device 10, and an input device 40 which is used by the user to input information to the numerical control device 10.

[0011] The numerical control device 10 controls the operation of the spindle motor 20 and other components according to an operation program (called a machining program in the numerical control device) so that a predetermined machining operation can be performed on the workpiece in the machine tool 1. The numerical control device 10 can be implemented by one or more computer devices that have memory, a processor (CPU), input / output interfaces, etc., and execute an appropriate control program. The components of the numerical control device 10 described below are classifications of the functions of the numerical control device 10 and do not necessarily have to be clearly distinguishable in terms of physical configuration and program configuration.

[0012] The spindle motor 20 is typically a motor that rotates a cutting tool or workpiece. The spindle motor 20 operates according to the operating program as described above, but the load may fluctuate independently of the rotational speed depending on the machining conditions. The rotational speed detector 21, current detector 22, and temperature detector 23 can each be composed of well-known sensors.

[0013] The display device 30 is a well-known display that displays information according to signals input from the numerical control device 10. The display device 30 may be configured integrally with the numerical control device 10. The input device 40 is a device for the user to input information to the numerical control device 10, and may be a well-known configuration such as a keyboard or mouse. The input device 40 may also be configured integrally with the numerical control device 10. Furthermore, the input device 40 may be configured integrally with the display device 30. Specifically, the display device 30 and the input device 40 may be a single input / output device such as a touch panel.

[0014] In this embodiment, the numerical control device 10 includes a program storage unit 11, a motor control unit 12 that controls the operation of a motor that drives the drive shaft of the machine tool 1, including the spindle motor 20, and a motor monitoring unit 13 that performs the functions of the motor monitoring device according to this disclosure.

[0015] The program storage unit 11 stores the operation program to be executed in the machine tool 1. The operation program contains multiple blocks, each specifying a unit operation of the machine tool 1. Each block contains one or more words consisting of combinations of multiple characters. Generally, each block is initially assigned a sequence number to identify that block.

[0016] The motor control unit 12 executes the machining procedure described in the operation program by controlling the spindle motor 20 and the motors of the other drive axes of the machine tool 1 according to the operation program. The configuration of the motor control unit 12 is similar to that of well-known numerical control devices, so a detailed explanation is omitted.

[0017] The motor monitoring unit 13 includes a program acquisition unit 131, a rotation speed acquisition unit 132, an output value acquisition unit 133, an estimated time calculation unit 134, a history information storage unit 135, a graph display unit 136, a history information display unit 137, and a program display unit 138.

[0018] The program acquisition unit 131 acquires an operation program from the program storage unit 11 that specifies the operation to be monitored for the spindle motor 20. In other words, the program acquisition unit 131 loads the target operation program into the working memory.

[0019] The rotation speed acquisition unit 132 acquires the rotation speed of the spindle motor 20 from the rotation speed detector 21. The rotation speed acquisition unit 132 may also acquire the rotation speed of the spindle motor 20 via the motor control unit 12.

[0020] The output value acquisition unit 133 acquires output values of the spindle motor 20, such as current values, power values, torque values, etc. In this embodiment, the output value acquisition unit 133 is intended to acquire the current value of the spindle motor 20 from the current detector 22 and use the power value calculated from the current value as the output value. However, the output value acquisition unit 133 may be configured to use the detected value such as the current value as the output value as it is. The output value acquisition unit 133 may acquire the output value or the value necessary for calculating the output value from the motor control unit 12. Further, the output value acquisition unit 133 may acquire two or more types of output values.

[0021] Based on the winding temperature of the spindle motor 20 acquired from the temperature detector 23 and the current value or output value acquired by the output value acquisition unit 133, the estimated time calculation unit 134 calculates the estimated time until the spindle motor 20 reaches the overheat temperature when maintaining the rotation speed and output value at that time.

[0022] The history information storage unit 135 stores history information regarding the spindle motor 20 at regular time intervals. The history information includes the rotation speed of the spindle motor 20 as one of its elements, and as other elements, it may include the output value of the spindle motor 20, winding temperature, load level, the above-mentioned estimated time, etc., other state information, program position information indicating the position of the corresponding instruction of the operation program, modal information specifying the operation of the spindle motor 20, etc. Examples of the program position information include sequence number, line number, block number, etc. Examples of the modal information include instructions extracted from the operation program (not limited to those directly specifying the operation of the spindle motor 20, including instructions that can affect the operation of the spindle motor 20, such as instructions specifying tools), setting values such as the upper limit value of acceleration of the numerical control device 10, etc. Note that the load level can be determined based on the relationship with various ratings represented on a graph with the rotation speed and output value as two axes. Specifically, four load levels can be set: a continuous operation level where continuous operation is possible, a short-time operation level where intermittent operation within a certain time is possible, a maximum load operation level where operation is possible exceptionally for a very short time, and a non-operation level where operation is not allowed in principle even for a very short time, with the graphs of continuous rating, time rating, and maximum output as the boundary lines.

[0023] The time interval (unit time) for saving the history information may be a fixed time determined in advance, or may be set according to a user instruction via the input device 40 or the like. If the time interval is too short, the correspondence with the operation program cannot be confirmed. Therefore, by allowing the user to specify the time interval for saving the history information, the relationship between the operating state of the main shaft motor 20 and the operation program can be appropriately confirmed. FIG. 2 illustrates the content of the history information saved by the history information storage unit 135. As is clear from the figure, the history information storage unit 135 can be configured to create a relational database with the acquisition time of the data or the serial number as the unique key for the history information. Note that "-" in the figure means that it cannot be calculated or the corresponding information does not exist.

[0024] As illustrated on the left side of FIG. 3, the graph display unit 136 plots a marker indicating the rotational speed in a graph area where one axis (vertical axis) is time and the other axis (horizontal axis) is the rotational speed. Further, the graph display unit 136 changes the mode of the marker according to a predetermined index. As an index for determining the mode of the marker, state information of the main shaft motor 20 such as the above-described load level and the estimated time until the overheat temperature is reached can be used. By changing the mode of the marker according to state information such as the load level, the user can relatively easily grasp the state of the main shaft motor 20 at each time, for example, the margin.

[0025] Examples of the change in the mode of the marker by the graph display unit 136 include a change in color according to the value of the index such as blue, yellow, and red, a change in density or luminance according to the value of the index, and a change in the length or size of the marker according to the value of the index. That is, it is preferable that the graph display unit 136 changes the display mode of the marker based on a predetermined rule so that the magnitude of the value of the index can be identified. The graph display unit 136 may independently change a plurality of display modes of the marker based on a plurality of indexes in order to increase the amount of information that can be presented to the user.

[0026] The graph display unit 136 may be configured to allow setting the time range of the graph area based on a time specified by the user, the time of completion of acceleration or deceleration of the spindle motor 20, or the start and end times of the operation program. By appropriately setting the time range of the graph area, it becomes easier for the user to understand the time changes in the state of the spindle motor 20.

[0027] The graph display unit 136 may allow the user to select the markers to display so that they can be used as a trigger for the program display unit 138. Furthermore, the graph display unit 136 may make the graph easier to read by omitting markers when the rotation speed is zero, or when the load is considered extremely small based on some indicator, as shown in the figure.

[0028] The history information display unit 137 displays at least a portion of the history information as text information aligned with the time axis of the graph display unit 136, as illustrated on the left side of Figure 3. In the illustrated example, only update information is displayed for the sequence number (Seq No) and T-code (T-Code), and if they are not displayed, it means that there has been no change since the previous time. The items displayed by the history information display unit 137 may be configured so that the user can select from the history information.

[0029] The history information display unit 137 may be configured to allow selection of the history information to be displayed at each unit of time, so that it can be used as a trigger for the program display unit 138 to display the program.

[0030] The program display unit 138 displays an editable portion of the operating program corresponding to a marker selected by the user in the graph display unit 136 or to the history information selected by the user in the history information display unit 137. In other words, the program display unit 138 provides an interface for partially rewriting the operating program stored in the program storage unit 11. The history information display unit 137 may display the program on the same screen as the graph display unit 136 and the history information display unit 137, or it may occupy a larger area through screen switching or pop-up display.

[0031] The numerical control device 10 according to this embodiment includes a graph display unit 136 that plots a marker indicating the rotational speed of the spindle motor 20 in a graph region where one axis represents time and the other axis represents the rotational speed, changing its configuration according to a predetermined index. Therefore, the relationship between the change in the rotational speed of the spindle motor 20 and changes in other states of the spindle motor 20 can be easily grasped.

[0032] Although embodiments of the present disclosure have been described above, the present invention is not limited to the embodiments described above. Furthermore, the effects described in the embodiments described above are merely a list of preferred effects arising from the present invention, and the effects of the present invention are not limited to those described in the embodiments described above.

[0033] The motor monitoring device according to this disclosure may be provided independently of the numerical control device that controls the machine tool, and may be used to check the status of motors other than the spindle motor of the machine tool, such as the motor of a kneader. For example, the motor monitoring device according to this disclosure may be a management computer that manages one or more numerical control devices, such as a control device for a kneader, or a management computer that manages such a control device, with the functions of the motor monitoring unit of the above embodiment added.

[0034] In the motor monitoring device according to this disclosure, the history information display unit and the program display unit have arbitrary configurations and may have a configuration that displays history information or an operation program independently of the graph display unit. [Explanation of Symbols]

[0035] 1 Machine tools 10. Numerical control device (motor monitoring device) 11 Program Storage Unit 12 Motor control unit 13 Motor Monitoring Unit 131 Program Acquisition Section 132 Rotation speed acquisition unit 133 Output Value Acquisition Unit 134 Estimated Time Calculation Unit 135 History Information Storage Unit 136 Graph display section 137 History Information Display Unit 138 Program display section 20 Main shaft motor 21. Rotation speed detector 22 Current detector 23 Temperature detector 30 Display device 40 Input devices

Claims

1. A rotation speed acquisition unit that acquires the rotation speed of a motor operating according to an operating program, A history information storage unit that stores history information including the rotation speed at regular time intervals, A graph display unit plots the marker indicating the rotational speed on a graph region where one axis represents time and the other axis represents the rotational speed. A history information display unit that displays at least a portion of the aforementioned history information as text information aligned with the time axis of the graph display unit, Equipped with, The graph display unit changes the shape of the marker according to a predetermined indicator. The aforementioned history information display unit is a motor monitoring device that displays only the updated information in the history information that has changed since the previous time.

2. The motor monitoring device according to claim 1, wherein the history information storage unit sets the time interval according to the user's instructions.

3. The system further includes an output value acquisition unit that acquires the output value of the motor, The motor monitoring device according to claim 1 or 2, wherein the graph display unit changes the shape of the marker according to the load level determined based on the rotational speed and the output value.

4. The motor monitoring device according to claim 1 or 2, wherein the graph display unit sets the time range of the graph area based on a time specified by the user, the time of completion of acceleration or deceleration of the motor, or the start and end times of the operation program.

5. The motor monitoring device according to claim 1 or 2, further comprising, as one element of the history information, an estimated time calculation unit that calculates the estimated time until the motor reaches an overheat temperature while maintaining its current operating state.

6. The history information includes program location information that identifies the location of the operation program, The motor monitoring device according to claim 1 or 2, further comprising a program display unit that displays in an editable manner a portion of the operation program corresponding to a marker selected by the user in the graph display unit or to the history information selected by the user in the history information display unit.

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