Motor monitoring apparatus

Abstract

A motor monitoring apparatus according to one aspect of the present disclosure comprises: a program acquisition unit for acquiring a machining program that includes a plurality of blocks and is to be executed by a machine tool; a rotation speed acquisition unit that acquires the rotation speed of a main shaft motor of the machine tool; an output value acquisition unit that acquires an output value of the main shaft motor; a program display unit for displaying program portion information that includes information indicating a portion or a position of the machining program; a graph display unit for displaying a graph in which markers, each indicating a combination of the rotation speed and the output value, are plotted in a graph region with one axis for the rotation speed and another axis for the output value; and an information saving unit for saving, and associating with each other, the rotation speed and the output value, and the blocks.

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] Because this time rating changes depending on the rotation speed, it can be expressed as a graph (characteristic curve) with the rotation speed on the horizontal axis.In order to make it easier to understand the load state of a motor, it has been proposed to plot combinations of motor rotation speed and output at each point in time on a graph that displays characteristic curves of multiple time-rated outputs, with the rotation speed on the horizontal axis and the output as the rating.

[0004] Japanese Patent Application Publication No. 10-90011

[0005] Machine tools can be automatically operated by a numerical control device according to a machining program. In this case, the load state of the motor changes as the machining program progresses. Even if the current load on the motor is relatively large, short processes can be completed without problems. However, even if the current load on the motor is not that large, long processes may cause the motor to overheat. Therefore, a technology that can easily grasp the relationship between the motor load state and the machining program is desired.

[0006] A motor monitoring device according to one aspect of the present disclosure comprises a program acquisition unit that acquires a machining program including a plurality of blocks to be executed on a machine tool, a rotation speed acquisition unit that acquires the rotation speed of a spindle motor of the machine tool, an output value acquisition unit that acquires the output value of the spindle motor, a program display unit that displays program portion information including information indicating a portion of the machining program or its position, a graph display unit that displays a graph in which markers indicating combinations of the rotation speed and the output value are plotted in a graph area with one axis representing the rotation speed and the other axis representing the output value, and an information storage unit that stores the rotation speed and the output value in association with the blocks.

[0007] According to the present disclosure, the relationship between the load state of the motor and the machining program 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 diagram showing an example of a display by the motor monitoring device of FIG.

[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 can be realized by one or more computer devices that have a memory, a processor (CPU), an input / output interface, etc., and 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, and the load can vary regardless of the rotation speed depending on the machining conditions. The rotation speed detector 21, the current detector 22, and the temperature detector 23 can each be configured by a well-known sensor.

[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 a machining program to be executed by the machine tool 1. The machining 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] The motor control unit 12 executes the machining procedure described in the machining program by controlling the spindle motor 20 and the motors of the other drive axes of the machine tool 1 in accordance with the machining program. The configuration of the 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 , a state value acquisition unit 134 , an information storage unit 135 , a program display unit 136 , and a graph display unit 137 .

[0018] The program acquisition unit 131 acquires, from the program storage unit 11, a machining program that specifies the operation to be monitored of the spindle motor 20. In other words, the program acquisition unit 131 loads the target machining 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 and torque 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 of the current value or the like as the output value directly. The output value acquisition unit 133 may acquire the output value or a value necessary to calculate the output value from the motor control unit 12. Furthermore, the type of output value acquired by the output value acquisition unit 133 may be one type, or three or more types.

[0021] The state value acquisition unit 134 acquires a state value indicating the state of the spindle motor 20. In this embodiment, the state value acquisition unit 134 calculates an estimated time until the spindle motor 20 reaches an 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, and sets this estimated time as a first state value. The state value acquisition unit 134 also calculates the torque of the spindle motor 20 based on the current value acquired by the output value acquisition unit 133, and sets this torque as a second state value. Note that the state value acquisition unit 134 may use another index indicating the state of the spindle motor 20 as the state value; for example, the winding temperature of the spindle motor 20 may be used as the state value as is.

[0022] The information storage unit 135 stores the rotation speed acquired by the rotation speed acquisition unit 132, the output value acquired by the output value acquisition unit 133, and the state value acquired by the state value acquisition unit 134 in association with information identifying the corresponding block of the machining program acquired by the program acquisition unit 131, such as a sequence number or a line number. In other words, the information storage unit 135 stores the rotation speed, the output value, and the state value in a manner that enables identification of which block of the machining program was executed. For example, the information storage unit 135 can be configured to store the rotation speed, the output value, the state value, and the sequence number as table data with the rotation speed, the output value, the state value, and the sequence number as data items.

[0023] Typically, the rotation speed, output value, and status value are acquired in short cycles, so multiple combinations of rotation speed, output value, and status value may be acquired for one block. However, the information storage unit 135 may store one piece of data for one block so that the sequence number is a unique key that does not overlap between data. In this case, the rotation speed, output value, and status value corresponding to each block are stored as their representative values. To ensure safety, it is preferable that the representative values ​​of the rotation speed, output value, and status value be the values ​​that indicate the highest load among the values ​​corresponding to that block (maximum values ​​for rotation speed, current value, and temperature, and minimum values ​​for estimated time).

[0024] The program display unit 136 displays program portion information including information indicating a portion of the machining program or its position (e.g., line numbers, etc.) on the display screen of the display device 30. In other words, the program display unit 136 creates at least a portion of the data for the screen displayed by the display device 30. Typically, as illustrated in FIG. 2 , the program display unit 136 is configured to set a program display area of ​​a certain size on the display screen of the display device 30 to display the machining program, and to display as many lines of the machining program as the program display area allows as the program portion information. The program display unit 136 may display the machining program including information such as sequence numbers as the program portion information, or may extract and display only words specifying the operation of the machine tool from the machining program, or may display only information indicating the position of the machining program, such as sequence numbers and line numbers, or may be configured to switch between these display modes.

[0025] The program display unit 136 preferably displays the position in the machining program that the user wishes to check in detail in a selectable manner, for example, by character, word, block, etc., and may be configured to allow the user to select multiple blocks. The result of the user's selection of the position in the machining program can be reflected in the display content of the graph display unit 137, as will be described later.

[0026] The program display unit 136 is preferably configured to be able to accept editing of the machining program. In other words, it is preferably configured to allow the user to select words or text displayed on the program display unit 136, rewrite the selected words or text, and store the rewritten machining program in the program storage unit 11.

[0027] The program display unit 136 may display the program portion information in a manner that allows the magnitude of the rate of change of at least one of the rotation speed and the output value to be distinguished. As a specific example, the program display unit 136 may change the color or pattern of the text, background, frame, etc. displaying the information of the corresponding block depending on the category of change rate for which a predetermined boundary value is set or the category for which the boundary value is set as a ratio to the maximum change rate. Typically, the program display unit 136 may be configured to classify the rate of change of the rotation speed and the output value into three categories, and display the text or background of blocks with small change rates in blue, the text or background of blocks with medium change rates in yellow, and the text or background of blocks with large change rates in red. It is preferable that this color be the color of the block with the larger rate of change between the category to which the rotation speed belongs and the category to which the output value belongs. In this way, by displaying the program portion information in a manner that allows the magnitude of the rate of change of at least one of the rotation speed and the output value to be distinguished in each block, it is possible to easily identify blocks that cause large changes in at least one of the rotation speed and the output value. The rate of change may also be the maximum rate of change within the block, or the rate of change between the representative values ​​of the blocks.

[0028] The program display unit 136 may change the manner in which the program portion information is displayed so as to make it possible to distinguish the load level determined based on the combination of the rotation speed and the output value. As a specific example, the program display unit 136 may indicate to which load zone, set in the graph display unit 137 described below, the combination of the rotation speed and the output value associated with the displayed block belongs by using different colors or patterns of the characters, background, frame, etc. that display the block information.

[0029] The program display unit 136 may change the display mode depending on the state value, thereby displaying the magnitude of the state value continuously or in stages in a distinguishable manner. The program display unit 136 may add characters to each block indicating the value of the state value or a classification of its magnitude, or may indicate the magnitude of the state value by using different colors or patterns of the characters, background, frame, etc. that display the information of each block. Typically, the program display unit 136 may be configured to change the display mode of a block depending on which of three or more classifications the state value belongs to, which divides the range of possible states into. In this case, the program display unit 136 may be able to set boundary values ​​for the state value that change the display mode of the block according to user input.

[0030] Furthermore, as will be described later, the program display unit 136 may identifiably display blocks associated with combinations of rotation speeds and output values ​​whose difference from the coordinate position selected in the graph display unit 137 is equal to or less than a predetermined margin. By clearly displaying blocks resulting in values ​​that the user is interested in in the graph display unit 137, the user can easily grasp problems with the machining program. Note that by setting a margin when selecting a coordinate position, blocks having similar combinations of rotation speeds and output values ​​can be displayed as candidates, allowing for rough selection.

[0031] The graph display unit 137 displays a graph on the display screen of the display device 30, 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 137 may display a graph of a single output value, or may display graphs of multiple output values ​​side by side. In addition, it is preferable that the graph display unit 137 provides the above-mentioned coordinate position selection function.

[0032] In order to make it easier to understand the relationship between the machining program and the rotation speed and output value, it is preferable that the program display unit 136 and the graph display unit 137 simultaneously display program portion information and a graph on the same screen, as exemplified in Fig. 2. Alternatively, the program display unit 136 and the graph display unit 137 may display exclusively. In this case, when switching to the screen using the graph display unit 137, the rotation speed and output value corresponding to the block selected in the program display unit 136 may be plotted, and program portion information may be displayed that highlights the blocks corresponding to the rotation speed and output value near the coordinate value selected in the graph display unit 137 when switching to the display using the program display unit 136.

[0033] The graph display unit 137 has a graph area setting unit 1371 that divides the graph area into multiple load zones and displays the multiple load zones in an identifiable manner, and a plotting unit 1372 that plots by changing the state of the marker depending on the state value.

[0034] The graph area setting unit 1371 divides the graph area into a plurality of load zones with different load levels based on a plurality of time ratings of the spindle motor 20 for possible combinations of rotation speed and output value. This allows the user to easily grasp the risk level of the spindle motor 20.

[0035] The graph area setting unit 1371 preferably displays a plurality of load zones in a distinguishable manner using colors or patterns. By using colors or patterns, it is easy to understand which load zone a combination of rotation speed and output value belongs to. Furthermore, by using colors or patterns that make it easy to intuitively understand the level of load in that load zone, such as blue, yellow, or red, the risk of the operating state of the spindle motor 20 can be easily understood.

[0036] If the combination of the rotation speed and output value of the spindle motor 20 is equal to or less than the continuous rating, the operation state can be continued indefinitely with respect to the load on the spindle motor 20. For this reason, it is preferable that the upper limit of the load zone with the lowest load level be the curve representing the continuous rating.

[0037] The graph area setting unit 1371 preferably sets the boundary of one of the multiple load zones, preferably the lower limit of the load zone with the highest load level, as a line connecting the maximum values ​​of multiple time ratings (for example, short-time ratings and repetitive ratings with different load time rates) at the same rotation speed. A combination of rotation speed and output value plotted in an area beyond this boundary line indicates a dangerous output state that could immediately cause a malfunction. Conversely, if the boundary line is not exceeded, there is a possibility that no problem will occur for a short period of time.

[0038] The graph area setting unit 1371 may be configured to select at least one boundary of a plurality of load zones in accordance with a user's input. Specifically, the graph area setting unit may be configured to select the boundary of the load zone from the above-mentioned continuous rating, the maximum value of a plurality of time ratings, a plurality of short-term ratings with different load times, and a plurality of repetitive ratings with different load time rates. This allows a load zone that is deemed appropriate to be set in consideration of the type of machining to be performed by the machine tool 1, thereby making it possible to more appropriately grasp the risk to the spindle motor 20.

[0039] The plot section 1372 plots combinations of rotation speeds and output values ​​while indicating the magnitude of the status values ​​by differences in the shape, size, color, pattern, etc. of the markers (in FIG. 2 , the inside of the rounded outer edge is hatched). This allows the user to simultaneously grasp the operating state of the spindle motor 20 at that time, which is indicated by the rotation speed and output value, as well as the status values, which may be affected by the previous operating state of the spindle motor 20. For example, even if the status value indicates that the temperature of the spindle motor 20 is increasing, if the load level at that time is low, it may be determined that there is no risk of the spindle motor 20 temperature increasing further. Conversely, even if the load level at that time is not very high, it may be determined that there is a risk of overheating if the operating state is continued. The markers may have an outer edge that makes it easy to distinguish them from the color or pattern of the graph area and a filled-in portion that indicates the status value. In this way, by the plot section 1372 indicating the status values ​​by the markers, the user can grasp the operating state of the spindle motor 20 from multiple perspectives.

[0040] The plot unit 1372 may continuously change the size, color, etc. of the marker depending on the value of the state value. However, it is preferable to determine the appearance of the marker depending on which of three or more divisions the range of possible state values ​​the state value belongs to. By gradually changing the appearance of the marker, the magnitude of the state value can be clearly presented. The state value divisions may be preset or may be dynamically changed. For example, if the state value is an estimated time until the overheat temperature is reached, the state value (estimated time) at the moment when the combination of the rotation speed and output value exceeds the continuous rating may be set as the maximum value of the range of possible state values, and a predetermined ratio of this maximum value to the value of the boundary value of the state value division may be set as the boundary value. Typically, the plot unit 1372 may be configured to divide the range of possible state values ​​into three divisions by setting the boundary value so as to equally divide the maximum value into three.

[0041] The plot unit 1372 may also be configured to be able to set a boundary value of the state value at which the state of the marker is changed in accordance with a user input. The boundary value may be specified as an absolute value or as a ratio to a maximum value. The boundary value may also be selected by the user from a plurality of preset options. This allows the state of the marker to be changed at a timing deemed appropriate in consideration of the content of machining to be performed by the machine tool 1, allowing the user to more appropriately grasp the risk to the spindle motor 20.

[0042] As described above, the plot unit 1372 is preferably configured to selectively plot the rotation speed and output value corresponding to the selected or edited position of the machining program when the position of the machining program is selected or edited in the program display unit 136. In particular, when the user selects multiple blocks in the program display unit 136, the plot unit 1372 preferably plots the rotation speed and output value corresponding to the selected multiple blocks simultaneously or continuously as a moving image. This allows the user to easily check the rotation speed, output value, and status value of the spindle motor 20 in the block of the machining program for which the user is to check or edit.

[0043] The numerical control device 10 according to this embodiment comprises an information storage unit 135 that stores the rotation speed and output value of the spindle motor 20 in association with blocks of the machining program; a program display unit 136 that displays program portion information including information indicating a portion of the machining program or its position; and a graph display unit 137 that displays a graph in which markers indicating combinations of the rotation speed and output value of the spindle motor 20 are plotted in a graph area with one axis representing the rotation speed and the other axis representing the output value, making it easy to grasp the relationship between the load state of the motor plotted on the graph and the program being executed at that time.

[0044] 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.

[0045] The motor monitoring device according to the present disclosure may be provided independently of a numerical control device that controls a machine tool. For example, the motor monitoring device according to the present disclosure may be a management computer that manages one or more numerical control devices, to which the functionality of the motor monitoring unit of the above-described embodiment has been added.

[0046] The motor monitoring device according to the present disclosure may not have a state value acquisition unit, and the graph display unit may not have a function to change the state of the marker. Also, the motor monitoring device according to the present disclosure may not have a machining program editing function.

[0047] 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 Status value acquisition unit 135 Information storage unit 136 Program display unit 137 Graph display unit 1371 Graph area setting unit 1372 Plot unit 20 Spindle motor 21 Rotation speed detector 22 Current detector 23 Temperature detector 30 Display device 40 Input device

Claims

1. a program acquisition unit that acquires a machining program including a plurality of blocks to be executed in a machine tool; a rotation speed acquisition unit that acquires a rotation speed of a spindle motor of the machine tool; an output value acquisition unit that acquires an output value of the spindle motor; a program display unit that displays program portion information including information indicating a part or a position of the part of the machining program; a graph display unit that displays a graph in which a marker indicating a combination of the rotation speed and the output value is plotted in a graph area having one axis representing the rotation speed and the other axis representing the output value; an information storage unit that stores the rotation speed and the output value in association with the block; A motor monitoring device comprising:

2. The motor monitoring device according to claim 1 , wherein the program display unit and the graph display unit simultaneously display the program portion information and the graph on the same screen.

3. The motor monitoring device according to claim 1 or 2, wherein the information storage unit stores the maximum values ​​of the rotation speed and the output value in each of the blocks.

4. the program display unit displays a position in the machining program in a manner that allows a user to select the position, 3. The motor monitoring device according to claim 1, wherein the graph display unit plots the rotation speed and the output value corresponding to the block including the position selected on the program display unit.

5. the program display unit allows a user to select a plurality of the blocks; 5. The motor monitoring device according to claim 4, wherein the graph display unit plots the rotation speeds and the output values ​​corresponding to a plurality of the blocks selected on the program display unit simultaneously or successively.

6. The program display unit accepts editing of the machining program, 3. The motor monitoring device according to claim 1, wherein the graph display unit plots the rotation speed and the output value corresponding to the program portion information including a portion being edited in the program display unit.

7. 3. The motor monitoring device according to claim 1, wherein the program display section displays the program portion information in a manner that makes it possible to distinguish the magnitude of a rate of change of at least one of the rotation speed and the output value.

8. 3. The motor monitoring device according to claim 1, wherein the program display unit displays the program portion information in a manner that enables identification of a load level determined based on a combination of the rotation speed and the output value.

9. the graph display unit accepts a selection of a coordinate position of the graph area; The motor monitoring device according to claim 1 or 2, wherein the program display unit identifiably displays the blocks associated with combinations of the rotation speed and the output value whose difference from the selected coordinate position is within a predetermined margin amount.

10. A state value acquisition unit that acquires a state value indicating a state of the spindle motor, The motor monitoring device according to claim 1 , wherein at least one of the program display section and the graph display section changes a display mode in accordance with the state value.

11. The graph display unit includes: a graph area setting unit that divides the graph area into a plurality of load zones having different load levels based on a plurality of time ratings of the spindle motor for an expected combination of the rotation speed and the output value, and displays the plurality of load zones in a distinguishable manner; a plotting unit that plots the marker by changing a state of the marker in accordance with the state value; The motor monitoring device of claim 10, further comprising:

12. The motor monitoring device according to claim 10, wherein the program display section changes a manner of display of the block depending on which of three or more sections the state value belongs to, the range being divided into which the state value can take.

13. The motor monitoring device according to claim 12 , wherein the program display unit is capable of setting a boundary value of the state value that changes the manner of display of the block in accordance with a user's input.

14. The motor monitoring device according to claim 10 , wherein the state value acquisition unit calculates, as the state value, an estimated time until the spindle motor reaches an overheat temperature if the rotation speed and the output value at that time are maintained.