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

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, a history information storage unit that saves history information including the rotation speed at regular time intervals, and a graph display unit that plots a marker indicating the rotation speed in a graph area with one axis representing time and the other axis representing the rotation speed, and the graph display unit changes the appearance of the marker 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 a history 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 performs 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, 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, 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 history information storage unit 135 stores history information related to the spindle motor 20 at regular time intervals. The history information includes the rotational speed of the spindle motor 20 as one element, and may also include other status information such as the output value, winding temperature, load level, and estimated time of the spindle motor 20 as other elements, program position information indicating the position of the corresponding command in the operation program, and modal information specifying the operation of the spindle motor 20. Examples of program position information include sequence numbers, line numbers, and block numbers. Examples of modal information include commands extracted from the operation program (not limited to those directly specifying the operation of the spindle motor 20, but including commands that may affect the operation of the spindle motor 20, such as commands specifying tools), and settings of the numerical control device 10, such as the upper limit of acceleration. The load level can be determined in relation to various ratings represented on a graph with the rotational speed and output value as the two axes. Specifically, using the graphs of continuous rating, time rating, and maximum output as boundaries, four load levels can be set: a continuous operation level where continuous operation is possible, a short-term operation level where intermittent operation within a certain period of time is possible, a maximum load operation level where operation is exceptionally possible for an extremely short period of time, and an inoperable level where operation is not permitted even for an extremely short period of time in principle.

[0023] The time interval (unit time) for saving the history information may be a predetermined fixed time, or may be set according to a user instruction via the input device 40 or the like. If the time interval is too short, it will be impossible to confirm the correspondence with the operation program. Therefore, by allowing the user to specify the time interval for saving the history information, the relationship between the operating state of the spindle motor 20 and the operation program can be properly confirmed. Figure 2 shows an example of the content of the history information saved by the history information saving unit 135. As is clear from the figure, the history information saving unit 135 can be configured to create a relational database in which the history information is stored using the 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] As shown in the left side of Fig. 3, the graph display unit 136 plots a marker indicating the rotation speed in a graph area with one axis (vertical axis) representing time and the other axis (horizontal axis) representing the rotation speed. The graph display unit 136 also changes the appearance of the marker in accordance with a predetermined index. Status information of the spindle motor 20, such as the above-mentioned load level and estimated time until the overheat temperature is reached, can be used as the index for determining the appearance of the marker. By changing the appearance of the marker in accordance with status information such as the load level, the user can relatively easily grasp the status of the spindle motor 20 at each time, for example, the margin.

[0025] Examples of changes to the marker appearance by the graph display unit 136 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 graph display unit 136 change the display appearance of the marker based on a predetermined rule so that the magnitude of the index value can be identified. In order to increase the amount of information that can be presented to the user, the graph display unit 136 may change multiple display appearances of the marker independently based on multiple indexes.

[0026] The graph display unit 136 may be configured to be able to set the time range of the graph area based on a time specified by the user, the time at which acceleration or deceleration of the spindle motor 20 is completed, or the start and end times of an operation program. By appropriately setting the time range of the graph area, the user can easily grasp the change over time in the state of the spindle motor 20.

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

[0028] As shown in the left side of Fig. 3, the history information display unit 137 displays at least a portion of the history information as text information aligned along the time axis with the graph display unit 136. In the example shown, the sequence number (Seq No) and T-code (T-Code) only display update information, and if there is no description, it means that there has been no change from the previous time. The items displayed by the history information display unit 137 may be configured so that the user can select them from the history information.

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

[0030] The program display unit 138 displays in an editable manner a portion of the operation program corresponding to a marker selected by the user in the graph display unit 136 or 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 operation 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 may occupy a larger area by screen switching or pop-up display.

[0031] The numerical control device 10 according to this embodiment is provided with a graph display unit 136 that plots a marker indicating the rotation speed of the spindle motor 20 in a graph area with one axis representing time and the other axis representing the rotation speed, with the marker's appearance changing in accordance with a predetermined index. This makes it easy to grasp the relationship between changes in the rotation speed of the spindle motor 20 and changes in other states of the spindle motor 20.

[0032] 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.

[0033] 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, etc. 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, or a management computer that manages such a controller, to which the functionality of the motor monitoring unit of the above-described embodiment has been added.

[0034] In the motor monitoring device according to the present disclosure, the history information display unit and the program display unit may have any configuration, and may be configured to display the history information or the operating program independently of the graph display unit.

[0035] 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 History information storage unit 136 Graph display unit 137 History information display unit 138 Program 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; a history information storage unit that stores history information including the number of rotations at regular time intervals; a graph display unit for plotting a marker indicating the number of revolutions in a graph area having one axis representing time and the other axis representing the number of revolutions; Equipped with A motor monitoring device, wherein the graph display unit changes the appearance of the marker according to a predetermined index.

2. The motor monitoring device according to claim 1 , wherein the history information storage unit sets the time interval in accordance with an instruction from a user.

3. An output value acquisition unit that acquires an output value of the motor is further provided, 3. The motor monitoring device according to claim 1, wherein the graph display section changes a state of the marker in accordance with a load level determined based on the rotation speed and the output value.

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

5. The motor monitoring device according to claim 1 or 2, further comprising a history information display unit that displays at least a portion of the history information as character information aligned along a time axis with the graph display unit.

6. The motor monitoring device according to claim 5 , further comprising an estimated time calculation unit that calculates, as one element of the history information, an estimated time until the motor reaches an overheat temperature if the operating state at that time is maintained.

7. the history information includes program location information that identifies a location of the operation program; The motor monitoring device according to claim 5 , further comprising a program display unit that displays in an editable manner a portion of the operation program corresponding to the marker selected by the user in the graph display unit or the history information selected by the user in the history information display unit.