Motor monitoring device

Abstract

According to one embodiment of the present disclosure, a motor monitoring device that can easily ascertain the state of a motor comprises a rotational speed acquisition unit that acquires the rotational speed of a motor that operates in accordance with an operation program, an output value acquisition unit that acquires an output value for the motor, and a graph display unit that plots a marker that represents a combination of the rotational speed and the output value at a graph area where one axis is the rotational speed and the other axis is the output value. The graph display unit has a unit area setting unit that sets a plurality of unit areas that divide the graph area into a grid and a format modification unit that modifies the display format of the marker by unit area in accordance with a prescribed indicator.

Description

Motor Monitoring Device

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

[0002] For example, in motors where the load can vary greatly, such as the spindle motor of a machine tool, if the load continues to be high, heat may accumulate and the motor may overheat. Various time ratings may be set for such motors so that they can operate without overheating under specific conditions. JIS-C4034-1, for example, specifies time ratings such as a continuous rating that allows continuous operation, a short-term rating that allows operation for a certain period of time (load time) from room temperature, and a repetitive rating that allows operation for a certain period of time (load time rate) within a specified cycle time.

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

[0004] Patent No. 5628994

[0005] Simply estimating the time until overheating does not allow easy understanding of the safety and remaining capacity of the motor's operation. Specifically, when adjusting a setting value such as motor speed to minimize the margin for overheating and perform machining as efficiently as possible, it is not easy to determine how much to increase or decrease the setting value. For this reason, a technology that allows easy understanding of the motor's status is desired.

[0006] A motor monitoring device according to one aspect of the present disclosure comprises a rotation speed acquisition unit that acquires the rotation speed of a motor operating according to an operating program, an output value acquisition unit that acquires the output value of the motor, and a graph display unit that plots a marker indicating a combination of the rotation speed and the output value in a graph area having the rotation speed on one axis and the output value on the other axis, wherein the graph display unit has a unit area setting unit that sets a plurality of unit areas by dividing the graph area into a grid pattern, and a mode change unit that changes the display mode of the marker for each unit area according to a predetermined index.

[0007] According to the present disclosure, the state of the motor can be easily grasped.

[0008] It is a block diagram showing the configuration of a machine tool equipped with a motor monitoring device according to a first embodiment of the present disclosure. It is a table showing an example of information stored in an information storage unit of the motor monitoring device of Figure 1. It is a diagram showing an example of a display by the motor monitoring device of Figure 1.

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Fig. 1 is a block diagram showing the configuration of a machine tool 1 equipped with a motor monitoring device according to a 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 a screen in accordance with the numerical control device 10, and an input device 40 which a user uses 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 in accordance with an operation program (called a machining program in the numerical control device) so that the machine tool 1 can perform predetermined machining on the workpiece. The numerical control device 10 has a memory, a processor (CPU), an input / output interface, etc., and can be realized by one or more computer devices that execute appropriate control programs. 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 a workpiece. The spindle motor 20 operates according to the operation program as described above, but the load may vary depending on the machining situation, regardless of the rotation speed. The rotation speed detector 21, current detector 22, and temperature detector 23 may each be configured using 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 that allows a user to input information to the numerical control device 10, and may have a well-known configuration such as a keyboard or a 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 memory unit 11, a motor control unit 12 that controls the operation of the motor that drives the drive axis of the machine tool 1, including the spindle motor 20, and a motor monitoring unit 13 that executes the functions of the motor monitoring device according to the present disclosure.

[0015] The program storage unit 11 stores an operation program to be executed by the machine tool 1. The operation program includes a plurality of blocks, each of which specifies a unit operation of the machine tool 1. Each block includes one or more words each made up of a combination of a plurality of characters. Generally, each block is initially assigned a sequence number to identify the block.

[0016] In accordance with the operation program, motor control unit 12 executes the machining procedure described in the operation program by controlling spindle motor 20 and the motors of the other drive axes of machine tool 1. The configuration of motor control unit 12 is similar to that of a well-known numerical control device, and therefore a detailed description thereof will be 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 , an information storage unit 135 , and a graph display unit 136 .

[0018] The program acquisition unit 131 acquires, from the program storage unit 11, an operation program that specifies the operation to be monitored of 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 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 a current value, a power value, and a torque value. In the present embodiment, the output value acquisition unit 133 acquires the current value of the spindle motor 20 from the current detector 22 and uses the power value calculated from the current value as the output value. However, the output value acquisition unit 133 may be configured to use a detected value such as a current value as the output value as is. The output value acquisition unit 133 may acquire an output value or a value required to calculate an output value from the motor control unit 12. Furthermore, the output value acquisition unit 133 may acquire two or more types of output values.

[0021] The estimated time calculation unit 134 calculates the estimated time until the spindle motor 20 reaches the overheat temperature if the rotation speed and output value at that time are maintained, 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.

[0022] The information storage unit 135 stores operation information related to the operating state of the spindle motor 20 at regular time intervals. The operation information includes the rotation speed and output value, and may also include position information of corresponding commands in the operation program, modal information specifying the operation of the spindle motor 20, etc. Examples of position information in the operation program include sequence numbers, line numbers, block numbers, etc. Examples of modal information include commands extracted from the operation program (not limited to those that directly specify the operation of the spindle motor 20, but also including commands that may affect the operation of the spindle motor 20, such as commands specifying tools), and setting values ​​of the numerical control device 10, such as the upper limit of acceleration. In addition, the information storage unit 135 may pre-calculate values ​​such as load levels used in the graph display unit 136, as described below, and store them as one element of the operation information.

[0023] The time interval for saving the driving information may be a predetermined fixed time, or may be a time obtained by dividing the processing time estimated from the operation program by a predetermined number of planned driving information acquisitions. The information storage unit 135 may also be configured to save the driving information at a time interval specified by the user via the input device 40 or the like. FIG. 2 shows an example of the contents of the driving information saved by the information storage unit 135. As is clear from the figure, the information storage unit 135 may be configured to create a relational database in which the driving information is stored using the data acquisition time or serial number as a unique key. Note that a "-" in the figure indicates that calculation is impossible or that the relevant information does not exist.

[0024] 3, the graph display unit 136 displays a graph in which markers indicating combinations of rotation speed and output value are plotted in a graph area with one axis representing the rotation speed and the other axis representing the output value. The graph display unit 136 has a unit area setting unit 1361, a load zone setting unit 1362, a mode changing unit 1363, a margin setting unit 1364, and a proposal display unit 1365.

[0025] The unit area setting unit 1361 sets a plurality of unit areas by dividing the graph area into a grid pattern. In FIG. 3 , the boundaries of the unit areas are indicated by dashed lines. These unit area boundaries are used to illustrate the unit areas and may not actually exist on the screen displayed on the display device 30. The unit area setting unit 1361 may determine the size of the unit area based on a user input. This allows the manner changing unit 1363 to set a sufficient number of unit areas while ensuring the amount of information necessary to change the display manner of the marker. The unit area setting unit 1361 may be configured to allow the user to specify the length of the unit area for each axis, or the number of unit areas (number of divisions) for each axis.

[0026] The load zone setting unit 1362 divides the graph area into multiple load zones with different load levels. The load zones can be set using combinations of rotation speed and output value at which the load on the spindle motor 20 is considered to be equal, for example, various ratings, as boundaries. In FIG. 3 , the graph area is divided into four zones by the continuous rating, time rating, and maximum output, respectively, indicated by two-dot chain lines: a continuous load zone where continuous operation is possible, a short-term load zone where intermittent operation is possible, a maximum load zone where operation is possible on an exceptional basis if temporary, and an inoperable zone where even short-term operation is not permitted. Note that the boundaries between these load zones do not necessarily have to exist on the screen actually displayed on the display device 30.

[0027] The mode change unit 1363 changes the display mode of the marker for each unit area according to a predetermined index. This makes it possible to display additional information on a two-dimensional graph and present the state of the spindle motor 20 to the user in an easily understandable manner. Examples of changes to the marker mode by the mode change unit 1363 include changing the color according to the index value, such as blue, yellow, or red, changing the density or brightness according to the index value, or changing the length or size of the marker according to the index value. In other words, it is preferable that the mode change unit 1363 changes the display mode of the marker based on a predetermined rule so that the magnitude of the index value can be identified.

[0028] Examples of indices for determining the mode of the marker include the frequency of appearance of a combination of rotation speed and output value for each unit area, the load level determined by the zone set by the load zone setting unit 1362, and the estimated time required to reach the overheat temperature calculated by the estimated time calculation unit 134. The mode change unit 1363 may change multiple modes of the marker according to different indices.

[0029] When changing the appearance of the marker according to the appearance frequency for each unit area of ​​a combination of rotation speed and output value, the appearance change unit 1363 may change the display appearance of the marker according to the ratio of the number of pieces of operation information belonging to a unit area to the total number of pieces of operation information or the number of pieces of operation information with a value (excluding pieces of operation information with a zero output value) in a predetermined time range. In this way, by using relative values ​​rather than absolute numbers for the frequency, the appearance of the marker can be changed more significantly, allowing the user to relatively easily grasp the state of the spindle motor 20. The time range for counting the appearance frequency may be set based on the completion of acceleration or deceleration of the spindle motor 20, or may be the entire range from the start to the end of operation of the spindle motor 20.

[0030] The margin setting unit 1364 sets a margin amount, which is the allowable range of the distance from the boundary of the load zone for a combination of rotation speed and output value. In FIG. 3, the boundary of the allowable range is shown by a dashed line. In the example shown, the allowable range is set for each axis, so the boundary line is rectangular, but the allowable range may also be set as a two-dimensional distance taking both axes into consideration so that the boundary is circular. Note that the boundary of this allowable range does not necessarily exist on the screen actually displayed on the display device 30.

[0031] The suggestion display unit 1365 adds a suggestion display to the marker, suggesting a change in the operating conditions of the spindle motor 20 based on the load level. In FIG. 3 , a left-down arrow suggesting a reduction in the load is added to a marker of a load level exceeding the time rating, and a right-up arrow suggesting an increase in the load is added to a marker of a load level below the time rating. Note that the output value of the spindle motor 20 is not set by itself but increases mainly in conjunction with an increase in the rotation speed of the spindle motor 20. As a result, the combination of rotation speed and output value moves in the direction indicated by the arrow in the suggestion display. The suggestion display unit 1365 may be configured to display suggestion displays selectable by the user, and to launch an editor that displays the corresponding portion of the operating program in an editable manner when a suggestion display is selected.

[0032] The proposal display unit 1365 may be configured to add a proposal display when the distance from the boundary of the load zone of a combination of rotation speed and output value is equal to or greater than a margin amount. If an increase in output is proposed when a combination of rotation speed and output value is close to the boundary of the load zone, there is a risk that the changed combination of rotation speed and output value will exceed the boundary of the load zone. Therefore, it is preferable to propose a change in the operating conditions of the spindle motor 20 only when there is a margin of distance to the boundary of the load zone. When proposing a reduction in output, there is no need to consider the margin amount from a safety perspective, but reducing output may have the disadvantage of increasing machining time. Therefore, it is possible not to actively propose a reduction in output when the combination is close to the boundary of the load zone.

[0033] The numerical control device 10 according to this embodiment is equipped with a graph display unit 136 having a unit area setting unit 1361 that sets a plurality of unit areas by dividing the graph area into a grid, and a mode change unit 1363 that changes the display mode of the marker for each unit area according to a predetermined index, thereby enabling the user to grasp the state of the spindle motor 20 from multiple perspectives.

[0034] Although the embodiments of the present disclosure have been described above, the present invention is not limited to the above-described embodiments. Furthermore, the effects described in the above-described embodiments are merely a list of preferred effects resulting from the present invention, and the effects of the present invention are not limited to those described in the above-described embodiments.

[0035] The motor monitoring device according to the present disclosure may be provided independently of a numerical control device that controls a machine tool, and may be used to check the status of a motor other than the spindle motor of a machine tool, such as a motor for a kneader. For example, the motor monitoring device according to the present disclosure may be a management computer that manages one or more numerical control devices, such as a controller for a kneader or the like, with the motor monitoring unit functions of the above-described embodiments added to the management computer that manages such a controller. Furthermore, in the motor monitoring device according to the present disclosure, the load zone setting unit, margin setting unit, and proposal display unit may be configured as desired.

[0036] REFERENCE SIGNS LIST 1 Machine tool 10 Numerical control device (motor monitoring device) 11 Program storage unit 12 Motor control unit 13 Motor monitoring unit 131 Program acquisition unit 132 Rotation speed acquisition unit 133 Output value acquisition unit 134 Estimated time calculation unit 135 Information storage unit 136 Graph display unit 1361 Unit area setting unit 1362 Load zone setting unit 1363 Mode change unit 1364 Margin setting unit 1365 Proposal display unit 20 Spindle motor 21 Rotation speed detector 22 Current detector 23 Temperature detector 30 Display device 40 Input device

Claims

1. a rotation speed acquisition unit that acquires the rotation speed of a motor that operates according to an operation program; an output value acquisition unit that acquires an output value of the motor; a graph display unit for plotting a marker indicating a combination of the rotation speed and the output value in a graph area having one axis representing the rotation speed and the other axis representing the output value; Equipped with The graph display unit includes: a unit area setting unit that sets a plurality of unit areas by dividing the graph area into a lattice pattern; a display mode changing unit that changes a display mode of the marker for each unit area in accordance with a predetermined index; A motor monitoring device comprising:

2. An information storage unit that stores the rotation speed and the output value at regular time intervals, The motor monitoring device according to claim 1 , wherein the manner changing unit changes the display manner of the marker depending on an appearance frequency of a combination of the rotation speed and the output value for each of the unit regions.

3. The motor monitoring device according to claim 2 , wherein the manner changing unit changes the display manner of the marker depending on the frequency of occurrence of a combination of the rotation speed and the output value within a predetermined time range based on the completion of acceleration or deceleration of the motor.

4. The motor monitoring device according to claim 2 , wherein the manner changing unit changes the display manner of the marker in accordance with an occurrence frequency of a combination of the rotation speed and the output value over an entire range from a start of operation of the motor to a stop of operation.

5. The motor monitoring device according to claim 1 , wherein the manner changing unit changes a display manner of the marker so that a load level of the unit area can be identified.

6. The motor monitoring device according to claim 1 , wherein the unit area setting unit determines a size of the unit area based on an input from a user.

7. The graph display unit includes: a load zone setting unit that divides the graph area into a plurality of load zones having different load levels; 5. The motor monitoring device according to claim 1, further comprising a suggestion display unit that adds a suggestion display that suggests a change in an operating condition of the motor based on a load level to the marker.

8. the graph display unit further includes a margin setting unit that sets a margin amount that is an allowable range of a distance from a boundary of a load zone of the rotation speed and the output value, 8. The motor monitoring device according to claim 7, wherein the suggestion display unit adds the suggestion display when a distance from a boundary of a load zone of the combination of the rotation speed and the output value is equal to or greater than the margin amount.

9. The motor further includes an estimated time calculation unit that calculates an estimated time until the motor reaches an overheat temperature if the rotation speed and the output value at that time are maintained. The motor monitoring device according to claim 7 , wherein the manner changing unit changes a display manner of the marker in accordance with the estimated time.