Motor control device

Abstract

Provided is a technique capable of detecting an abnormality of an industrial machine when performing full-closed control on one axis by a plurality of motors in the industrial machine. This motor control device comprises: a first position acquiring unit for acquiring the position change of each motor on the basis of each of the detection signals of a plurality of first position detectors with which the plurality of motors are respectively provided; a second position acquiring unit for acquiring the position change of the one axis on the basis of the detection signal of a second position detector for directly detecting the position change of the one axis; a position calculation unit for calculating a position change of the one axis on the basis of the position change of each motor acquired by the first position acquiring unit; and an abnormality detection unit for detecting an abnormality of the industrial machine on the basis of the position change of the one axis calculated by the position calculation unit and the position change of the one axis acquired by the second position acquiring unit.

Description

[Technical Field]

[0001] The present disclosure relates to a motor control device. [Background technology]

[0002] Conventionally, in industrial machines that perform, for example, internal diameter machining or hole drilling, a technique has been disclosed in which the cutting edge of a cutting tool is moved in a U-axis direction perpendicular to the spindle, i.e., in the radial direction of rotation, while machining (see, for example, Patent Document 1). This technique is said to enable machining of tapered or curved surfaces in internal diameter machining or hole drilling. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-335809 Summary of the Invention [Problem to be solved by the invention]

[0004] In the technology of Patent Document 1, the present applicant has attempted to provide a position detector for each motor, as well as a position detector that directly detects the position of the U-axis, to perform full-closed control of the U-axis with multiple motors. In conventional U-axis mechanisms, providing a scale at the end of the machine would cause the scale cable to become tangled due to shaft rotation, making it difficult to handle, and so full-closed control has not been implemented. Therefore, at present, no system has been established that can detect abnormalities in industrial machinery when a single axis is fully closed-loop controlled with multiple motors.

[0005] The present disclosure aims to provide a technology capable of detecting an abnormality in industrial machinery when one axis of the industrial machinery is fully closed-loop controlled by multiple motors. [Means for solving the problem]

[0006] One aspect of the present disclosure is a motor control device that controls one axis in an industrial machine using multiple motors, and includes: a first position acquisition unit that acquires position changes of each motor based on detection signals from multiple first position detectors provided on each of the multiple motors; a second position acquisition unit that acquires position changes of the one axis based on detection signals from a second position detector that directly detects the position changes of the one axis; a position calculation unit that calculates the position changes of the one axis based on the position changes of each motor acquired by the first position acquisition unit; and an abnormality detection unit that detects an abnormality in the industrial machine based on the position changes of the one axis calculated by the position calculation unit and the position changes of the one axis acquired by the second position acquisition unit. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide a technology capable of detecting an abnormality in an industrial machine when one axis of the industrial machine is fully closed-loop controlled by a plurality of motors. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing an industrial machine equipped with a U-axis mechanism according to a first embodiment. [Figure 2] FIG. 2 is a block diagram showing the configuration of a motor control device. [Figure 3] FIG. 10 is a diagram showing an industrial machine equipped with a linear mechanism according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the description of the second embodiment, the description of the configuration common to the first embodiment will be omitted as appropriate.

[0010] [First embodiment] The industrial machine of the first embodiment is equipped with a U-axis mechanism that can move the cutting edge of the cutting tool in the U-axis direction perpendicular to the spindle, i.e., in the radial direction of rotation. Therefore, the industrial machine of this embodiment is applicable to, for example, the inner diameter machining of drilling pipes and drilling holes, and is capable of machining curved, tapered, and spherical surfaces. The industrial machine of this embodiment also includes a motor control device, which will be described later, and which performs full-closed control of the U-axis using multiple motors.

[0011] Fig. 1 is a diagram showing an industrial machine 100 equipped with a U-axis mechanism of the first embodiment. As shown in Fig. 1, the industrial machine 100 of this embodiment includes a spindle motor 110, a spindle transmission mechanism 120, a U-axis motor 130, a U-axis transmission mechanism 140, a feed screw 150, a cutting tool 160, and a scale 170.

[0012] The spindle motor 110 uses its rotational drive force to rotate the cutting tool 160 at high speed. An output shaft 111 of the spindle motor 110 is connected to a spindle gear 121 and rotates integrally therewith.

[0013] The spindle motor 110 is provided with a rotary encoder 112 as a first position detector. The rotary encoder 112 detects position information such as the rotation angle and position (angle) change of the spindle motor 110. A detection signal from the rotary encoder 112 is sent to a first position acquisition unit 11 of the motor control device, which will be described later.

[0014] The main shaft transmission mechanism 120 transmits the rotational driving force of the main shaft motor 110 to the cutting tool 160. The main shaft transmission mechanism 120 includes a main shaft gear 121, a base gear 122, and a holder 123.

[0015] 1, the main shaft gear 121 is a cylindrical spur gear with tooth traces parallel to the main shaft. The main shaft gear 121 is connected to the output shaft 111 of the main shaft motor 110 and is meshed with the base gear 122. Therefore, the rotational driving force of the main shaft motor 110 is transmitted to the base gear 122 via the main shaft gear 121, which rotates integrally with the output shaft 111.

[0016] The base gear 122 has a cylindrical shape, and an output shaft 131 of a U-axis motor 130 is inserted into its hollow portion. Teeth (not shown) are formed on the outer periphery of the base gear 122, and the base gear 122 is a spur gear that meshes with the main shaft gear 121.

[0017] The holding portion 123 is provided on the base gear 122 and rotates integrally with the base gear 122. The holding portion 123 holds the U-axis transmission mechanism 140 and also holds the cutting tool 160 via the U-axis transmission mechanism 140 and the feed screw 150. More specifically, as shown in FIG. 1 , the holding portion 123 includes a pair of holding plates 123a, 123b arranged opposite each other, and a connecting shaft 144 of the U-axis transmission mechanism 140 is rotatably supported by the pair of holding plates 123a, 123b.

[0018] The U-axis motor 130 moves the cutting tool 160 in the U-axis direction based on the difference in rotational drive force between it and the spindle motor 110, taking into account the gear ratios of the multiple gears described above or below. In other words, the rotation speed of the U-axis motor 130 is controlled in accordance with the rotation speed of the spindle motor 110, and when the rotational drive force by the U-axis motor 130, taking into account the gear ratios of the multiple gears, is the same as the rotational drive force by the spindle motor 110, taking into account the gear ratios of the multiple gears, the cutting tool 160 does not move in the U-axis direction, and its position in the U-axis direction remains constant.

[0019] Furthermore, the output shaft 131 of the U-axis motor 130 is inserted into the hollow portion of the base gear 122 and is connected to the first U-axis gear 141, and rotates integrally with the first U-axis gear 141.

[0020] The U-axis motor 130 is provided with a rotary encoder 132 as a first position detector. The rotary encoder 132 detects position information such as the rotation angle and position (angle) change of the U-axis motor 130. A detection signal from the rotary encoder 132 is transmitted to a first position acquisition unit 11 of the motor control device, which will be described later.

[0021] The U-axis transmission mechanism 140 transmits the difference between the rotational driving force of the U-axis motor 130 and the rotational driving force of the main shaft motor 110 to the feed screw 150. The U-axis transmission mechanism 140 includes a first U-axis gear 141, a second U-axis gear 142, a third U-axis gear 143, and a connecting shaft 144.

[0022] First U-shaft gear 141 is connected to output shaft 131 of U-shaft motor 130 and rotates integrally with output shaft 131. Second U-shaft gear 142 is meshed with first U-shaft gear 141, and is also connected to connecting shaft 144 and rotates integrally with connecting shaft 144. Third U-shaft gear 143 is connected to connecting shaft 144 and rotates integrally with connecting shaft 144, and is meshed with lead screw gear 152. As shown in FIG. 1 , first U-shaft gear 141 and second U-shaft gear 142 are conical bevel gears, and third U-shaft gear 143 is a spur gear.

[0023] When there is no difference between the rotational driving force of the U-axis motor 130 taking into consideration the gear ratios of the multiple gears and the rotational driving force of the main shaft motor 110 taking into consideration the gear ratios of the multiple gears, the rotational driving force is not transmitted to the third U-axis gear 143 and the third U-axis gear 143 does not rotate. In other words, the rotational driving force is transmitted to the third U-axis gear 143 and the third U-axis gear 143 rotates only when there is a difference between the rotational driving force of the U-axis motor 130 taking into consideration the gear ratios of the multiple gears and the rotational driving force of the main shaft motor 110 taking into consideration the gear ratios of the multiple gears.

[0024] The feed screw 150 converts the difference between the rotational driving forces of the spindle motor 110 and the U-axis motor 130, which are transmitted via the above-mentioned multiple gears, into a linear driving force in the U-axis direction. The feed screw 150 is configured by, for example, a ball screw. The feed screw 150 includes a screw shaft 151, a feed screw gear 152, and a nut 153.

[0025] The screw shaft 151 extends in the U-axis direction, i.e., in a direction perpendicular to the main shaft. A helical male screw is formed on the outer periphery of the screw shaft 151. A feed screw gear 152 is connected to the screw shaft 151, and the screw shaft 151 rotates integrally with the feed screw gear 152.

[0026] The feed screw gear 152 is meshed with the third U-axis gear 143. As a result, the difference in rotational driving force between the main shaft motor 110 and the U-axis motor 130, taking into account the gear ratios of multiple gears, is transmitted to the feed screw gear 152 via the third U-axis gear 143, causing the screw shaft 151 to rotate.

[0027] A male thread formed on the outer periphery of the screw shaft 151 is engaged with a female thread formed on the inner periphery of the nut 153 via steel balls (not shown). As a result, the nut 153 moves in the U-axis direction as the screw shaft 151 rotates. The nut 153 in this embodiment also functions as a tool holder for holding the cutting tool 160.

[0028] The cutting tool 160 cuts the workpiece by contacting its cutting edge 161 with the workpiece surface to be machined. The cutting tool 160 of this embodiment is capable of performing internal diameter machining and hole drilling by moving in the U-axis direction by the U-axis mechanism while rotating at high speed by the rotational driving force of the spindle motor 110.

[0029] Scale 170 is provided as a second position detector, and is a separate detector attached to nut 153, for example, as shown in FIG. 1. Scale 170 directly detects position information such as the position in the U-axis direction and position change. A detection signal from scale 170 is sent to second position acquisition unit 12 of the motor control device, which will be described later.

[0030] The industrial machine 100 having the above configuration operates as follows. First, when the rotational driving force of the spindle motor 110 is transmitted by the spindle transmission mechanism 120, the entire assembly including the cutting tool 160, U-axis transmission mechanism 140, and feed screw 150 rotates at high speed. This enables, for example, internal diameter machining and hole drilling.

[0031] At this time, the rotation speed of U-axis motor 130 is controlled so that the rotational drive force of U-axis motor 130, which takes into account the gear ratios of the multiple gears, matches the rotational drive force of spindle motor 110, which takes into account the gear ratios of the multiple gears. As a result, the rotational drive force is not transmitted to third U-axis gear 143, so cutting tool 160 does not move in the U-axis direction and is fixed at a certain position in the U-axis direction. This allows for planar machining, for example, in internal diameter machining or hole drilling.

[0032] In response to this, the rotation speed of the U-axis motor 130 is controlled so that a difference occurs between the rotational drive force of the U-axis motor 130, which takes into account the gear ratios of the multiple gears, and the rotational drive force of the spindle motor 110, which takes into account the gear ratios of the multiple gears. Then, a rotational drive force equivalent to this difference is transmitted to the third U-axis gear 143 and converted into a linear drive force by the feed screw 150, so that the cutting tool 160 moves in the U-axis direction. As a result, curved or tapered surfaces can be machined, for example, in internal diameter machining or hole drilling.

[0033] Next, the motor control device that performs full-closed control on the industrial machine 100 of this embodiment will be described in detail.

[0034] Fig. 2 is a block diagram showing the configuration of motor control device 1 according to the first embodiment. As shown in Fig. 2, motor control device 1 according to this embodiment includes first position acquisition unit 11, second position acquisition unit 12, position calculation unit 13, difference calculation unit 14, and abnormality detection unit 15.

[0035] The first position acquisition unit 11 acquires position information (hereinafter simply referred to as position change) such as a position change (speed) of the spindle motor 110 based on a detection signal from a rotary encoder 112 provided on the spindle motor 110. The first position acquisition unit 11 also acquires position information (hereinafter simply referred to as position change) such as a position change (speed) of the U-axis motor 130 based on a detection signal from a rotary encoder 132 provided on the U-axis motor 130.

[0036] The second position acquisition unit 12 acquires position information such as the position change (speed) of the U axis based on the detection signal of the scale 170 that directly detects the position change of the U axis.

[0037] The detection signals of the rotary encoder 112 and the rotary encoder 132 input to the first position acquisition unit 11 and the detection signal of the scale 170 input to the second position acquisition unit 12 are input in synchronization at a predetermined control period.

[0038] The position calculation unit 13 calculates the position change of the U-axis based on the position change of the spindle motor 110 and the position change of the U-axis motor 130 acquired by the first position acquisition unit 11. Specifically, the position calculation unit 13 calculates the position change of the U-axis based on the gear ratios of the above-mentioned multiple gears and the lead of the feed screw 150, in addition to the position change of the spindle motor 110 and the position change of the U-axis motor 130. Here, the lead of the feed screw 150 means the distance that the nut 153 moves in the U-axis direction when the screw shaft 151 makes one rotation.

[0039] Difference calculation unit 14 calculates the difference between the position change of the U-axis calculated by position calculation unit 13 and the position change of the U-axis directly acquired by second position acquisition unit 12. Note that at this time, the position change of the U-axis calculated by position calculation unit 13 is calculated from the position changes of each motor acquired in synchronization with the position change of the U-axis directly acquired by second position acquisition unit 12.

[0040] The abnormality detection unit 15 detects an abnormality in the industrial machinery 100 based on the position change of the U-axis calculated by the position calculation unit 13 and the position change of the U-axis directly acquired by the second position acquisition unit 12. Specifically, the abnormality detection unit 15 detects an abnormality in the industrial machinery 100 when the difference calculated by the difference calculation unit 14 is outside a predetermined range or when the absolute value of the difference calculated by the difference calculation unit 14 exceeds a predetermined threshold. The predetermined range and predetermined threshold are set as parameters after confirming calculation errors in advance through experiments or the like. The parameters may be written in the machining program or may be input by an operator using the motor control device 1.

[0041] An abnormality in the industrial machinery 100 may be a failure of any of the position detectors among the rotary encoder 112 of the spindle motor 110, the rotary encoder 132 of the U-axis motor 130, and the U-axis scale 170. Another abnormality in the industrial machinery 100 may be, for example, a case where any of the multiple gears are not meshing with each other.

[0042] Furthermore, the abnormality detection unit 15 is configured to issue an alarm when it detects an abnormality in the industrial machinery 100. For example, when it detects an abnormality in the industrial machinery 100, the abnormality detection unit 15 turns on a warning lamp or emits a warning sound, and also displays on a display screen of the motor control device 1 (not shown) or the like that an abnormality has occurred in the industrial machinery 100 to notify the user.

[0043] In the motor control device 1 according to this embodiment having the above configuration, when the industrial machine 100 is subjected to full-closed control, the abnormality detection process is carried out in the following procedure.

[0044] First, the first position acquisition unit 11 acquires the position change of the spindle motor 110 based on the detection signal of the rotary encoder 112 provided on the spindle motor 110, and also acquires the position change of the U-axis motor 130 based on the detection signal of the rotary encoder 132 provided on the U-axis motor 130.

[0045] Next, the second position acquisition unit 12 acquires the position change of the U axis based on the detection signal of the scale 170 that directly detects the position change of the U axis.

[0046] Next, the position calculation unit 13 calculates the position change of the U-axis based on the position change of the spindle motor 110 and the position change of the U-axis motor 130 acquired by the first position acquisition unit 11.

[0047] Next, the difference calculation unit 14 calculates the difference between the position change along the U axis calculated by the position calculation unit 13 and the position change along the U axis directly acquired by the second position acquisition unit 12.

[0048] Then, when the absolute value of the difference calculated by the difference calculation unit 14 exceeds a predetermined threshold, the abnormality detection unit 15 detects an abnormality in the industrial machine 100. In this manner, the abnormality detection process is executed.

[0049] According to this embodiment, the following effects are achieved.

[0050] The motor control device 1 according to this embodiment is provided with a position calculation unit 13 that calculates a position change of the U-axis based on the position change of the spindle motor 110 and the position change of the U-axis motor 130 acquired by the first position acquisition unit 11. The motor control device 1 according to this embodiment is also provided with an abnormality detection unit 15 that detects an abnormality in the industrial machine 100 based on the position change of the U-axis calculated by the position calculation unit 13 and the position change of the U-axis directly acquired by the scale 170 acquired by the second position acquisition unit 12.

[0051] As a result, according to this embodiment, it is possible to reliably detect an abnormality in the industrial machinery 100 even when one axis (U-axis) in the industrial machinery 100 is fully closed-loop controlled by a plurality of motors. Therefore, according to this embodiment, it is possible to reliably avoid damage to the industrial machinery 100.

[0052] Furthermore, the motor control device 1 according to this embodiment is provided with a difference calculation unit 14 that calculates the difference between the position change of the U-axis calculated by the position calculation unit 13 and the position change of the U-axis directly acquired from the scale 170 acquired by the second position acquisition unit 12. Furthermore, the motor control device 1 according to this embodiment is configured so that the abnormality detection unit 15 detects an abnormality in the industrial machine 100 when the difference calculated by the difference calculation unit 14 is outside a predetermined range or when the absolute value of the difference calculated by the difference calculation unit 14 exceeds a predetermined threshold.

[0053] As a result, according to this embodiment, abnormalities in the industrial machinery 100 can be detected more reliably, and damage to the industrial machinery 100 can be avoided more reliably.

[0054] Furthermore, in the motor control device 1 according to this embodiment, the abnormality detection unit 15 is configured to issue an alarm when it detects an abnormality in the industrial machinery 100. This allows the user to be notified of an abnormality in the industrial machinery 100 at an early stage, and encourages the user to stop the industrial machinery and take action to deal with the malfunction at an early stage.

[0055] Furthermore, the motor control device 1 according to this embodiment is configured to calculate the position change of the U-axis based on the gear ratios of multiple gears and the lead of the feed screw in addition to the position change of the spindle motor 110 and the position change of the U-axis motor 130. This makes it possible to calculate the position change of the U-axis more accurately, and to detect abnormalities in the industrial machine 100 with greater precision.

[0056] [Second embodiment] FIG. 3 is a diagram showing an industrial machine 200 equipped with a linear mechanism according to a second embodiment. As shown in FIG. 3, the industrial machine 200 according to this embodiment is equipped with a linear mechanism in which linear motors 210, 220 are stacked in two stages, and a cutting tool (not shown) is mounted on the upper linear motor 220. Therefore, depending on the relative positions of the linear motors 210, 220, it is possible to linearly move the cutting edge of the cutting tool in a predetermined axial direction, that is, in the example shown in FIG. 3, the X-axis direction. The industrial machine 200 according to this embodiment is also equipped with a motor control device 1 similar to that of the first embodiment, and the motor control device 1 performs full-closed control of the cutting tool in the X-axis direction using the linear motors 210, 220.

[0057] As shown in FIG. 3, the industrial machine 200 of this embodiment includes a linear motor 210 as a damper shaft provided on a machine base 300, and a linear motor 220 as a linear shaft provided on the linear motor 210.

[0058] The linear motor 210 includes a damper fixing part 211 provided on the machine base 300, and a damper moving part 212 that performs reciprocating motion in the X-axis direction along a linear guide provided on the damper fixing part 211.

[0059] The linear motor 220 includes a linear fixed part 221 provided on the damper movable part 212, and a linear movable part 222 that performs reciprocating motion in the X-axis direction along a linear guide provided on the linear fixed part 221.

[0060] Moreover, the industrial machine 200 of this embodiment includes a first linear scale 251 and a second linear scale 252 as a first position detector, and a third linear scale 253 as a second position detector.

[0061] A first linear scale 251 serving as a first position detector is provided on the machine base 300. The first linear scale 251 detects position information such as a change in position of the linear motor 210 in the X-axis direction. A detection signal from the first linear scale 251 is transmitted to a first position acquisition unit 11 of the motor control device 1.

[0062] The second linear scale 252 serving as a first position detector is provided on the machine base 300. The second linear scale 252 detects position information such as a change in position of the linear motor 220 in the X-axis direction. A detection signal from the second linear scale 252 is transmitted to the first position acquisition unit 11 of the motor control device 1.

[0063] A third linear scale 253 serving as a second position detector is provided on the damper movable part 212. The third linear scale 253 detects a change in the relative position of the linear motors 210 and 220 in the X-axis direction. A detection signal from the third linear scale 253 is transmitted to the second position acquisition unit 12 of the motor control device 1.

[0064] That is, the first position acquisition unit 11 acquires position changes of the movable parts of the multiple linear motors relative to the machine base 300. The second position acquisition unit 12 acquires relative position changes of the movable parts of the multiple linear motors. Then, the position calculation unit 13 calculates the relative position changes of the movable parts of the multiple linear motors based on the position changes of the movable parts of the multiple linear motors acquired by the first position acquisition unit 11 relative to the machine base.

[0065] The industrial machine 200 of this embodiment having the above configuration is subjected to full-closed control by the motor control device 1 as described above. At that time, abnormality detection processing is performed in the following procedure. Note that in this embodiment, the information acquired by the motor control device 1 is such that the position changes of the spindle motor 110 and the U-axis motor 130 in the first embodiment are replaced with position changes in the X-axis direction of the linear motors 210, 220, and the position change of the U-axis motor 130 in the first embodiment is replaced with position changes in the relative positions of the linear motors 210, 220 in the X-axis direction.

[0066] First, the first position acquisition unit 11 acquires the position change in the X-axis direction of the linear motor 210 based on the detection signal of the first linear scale 251, and acquires the position change in the X-axis direction of the linear motor 220 based on the detection signal of the second linear scale 252.

[0067] Next, the second position acquisition unit 12 directly acquires the change in the relative position of the linear motors 210 and 220 in the X-axis direction based on the detection signal of the third linear scale 253.

[0068] Next, the position calculation unit 13 calculates the change in the relative positions of the linear motors 210 and 220 in the X-axis direction based on the position changes of the linear motors 210 and 220 in the X-axis direction acquired by the first position acquisition unit 11.

[0069] Next, the difference calculation unit 14 calculates the difference between the position change in the relative position of the linear motors 210, 220 in the X-axis direction calculated by the position calculation unit 13 and the position change in the relative position of the linear motors 210, 220 in the X-axis direction directly acquired by the second position acquisition unit 12.

[0070] Then, when the absolute value of the difference calculated by the difference calculation unit 14 exceeds a predetermined threshold, the abnormality detection unit 15 detects an abnormality in the industrial machine 200. In this manner, the abnormality detection process is executed.

[0071] According to this embodiment, the same effects as those of the first embodiment are achieved.

[0072] The present disclosure is not limited to the above-described embodiments, and includes modifications and improvements within the scope of achieving the object of the present disclosure.

[0073] For example, the present disclosure is applicable to any system that uses multiple motors for full-closed control of one axis, and is widely applicable to conventionally known tandem control systems that use multiple motors to drive one driven object.

[0074] In the above embodiment, the abnormality detection unit 15 detects an abnormality in the industrial machinery 100 when the difference calculated by the difference calculation unit 14 is outside a predetermined range or when the absolute value of the difference calculated by the difference calculation unit 14 exceeds a predetermined threshold, but this is not limiting. The configuration may be such that the U-axis position change calculated by the position calculation unit 13 is compared with the U-axis position change directly acquired by the second position acquisition unit 12, and an abnormality in the industrial machinery 100 is detected based on the comparison result. [Explanation of symbols]

[0075] 1. Motor control device 11 First position acquisition section 12 Second position acquisition section 13 Position calculation section 14 Difference calculation part 15 Abnormality detection unit 100 Industrial Machinery 110 spindle motor (multiple motors) 112 Rotary encoder (first position detector) 121 Main shaft gear (gear) 122 Base gear (gear) 130 U-axis motor (multiple motors) 132 Rotary encoder (first position detector) 141 1st U-axis gear (gear) 142 2nd U-axis gear (gear) 143 3rd U-axis gear (gear) 152 Lead screw gear (gear) 150 lead screw 160 Cutting tools (tools) 170 scale (second position detector) 200 Industrial Machinery 210 Linear motor (multiple motors) 220 Linear Motor (Multiple Motors) 251 First linear scale (first position detector) 252 Second linear scale (first position detector) 253 3rd linear scale (2nd position detector)

Claims

1. A motor control device that performs full-closed control of one axis with multiple motors in an industrial machine, a first position acquisition unit that acquires position changes of each of the motors based on detection signals from a plurality of first position detectors provided for each of the plurality of motors; a second position acquisition unit that acquires a position change of the one axis based on a detection signal of a second position detector that directly detects a position change of the one axis; a position calculation unit that calculates a position change of the one axis based on the position changes of each motor acquired by the first position acquisition unit; an abnormality detection unit that detects an abnormality in the industrial machine based on the position change of the one axis calculated by the position calculation unit and the position change of the one axis acquired by the second position acquisition unit.

2. a difference calculation unit that calculates a difference between the position change about the one axis calculated by the position calculation unit and the position change about the one axis acquired by the second position acquisition unit, 2. The motor control device according to claim 1, wherein the abnormality detection unit detects an abnormality in the industrial machine when the difference calculated by the difference calculation unit is outside a predetermined range or when the absolute value of the difference exceeds a predetermined threshold.

3. The motor control device according to claim 1 or 2, wherein the abnormality detection unit issues an alarm when an abnormality in the industrial machine is detected.

4. The industrial machine is a plurality of gears that transmit rotational driving forces of the plurality of motors; a feed screw that converts the rotational driving force transmitted via the plurality of gears into a linear driving force in the one axial direction, The motor control device according to claim 1 , wherein the position calculation unit calculates the position change of the one axis based on a gear ratio of the plurality of gears and a lead of the feed screw.

5. The plurality of motors are all linear motors, the first position acquisition unit acquires position changes of movable parts of the plurality of linear motors with respect to a machine base; the second position acquisition unit acquires relative position changes of movable parts of the plurality of linear motors; 4. The motor control device according to claim 1, wherein the position calculation unit calculates relative position changes of the movable parts of the plurality of linear motors based on position changes of the movable parts of the plurality of linear motors with respect to a mechanical base acquired by the first position acquisition unit.

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