JP5888924B2 - Anomaly detection device - Google Patents

Description

  The present invention relates to an abnormality detection device that detects an abnormality of a driven part driven by a servomotor.

  As an example of an abnormality detection device that detects an abnormality of a driven part driven by a servo motor, for example, an invention described in Patent Document 1 is known. In the invention described in Patent Document 1, in order to analyze a failure of the control device due to deterioration over time, an output port is provided in the interface unit of the control device so that analysis data can be output to the outside. Then, by comparing the collected analysis data with the expected value data, it is determined whether there is an abnormal operation of the actuator due to deterioration over time.

JP 2007-096005 A

  However, in the invention described in Patent Document 1, it is possible to determine whether or not there is an abnormality in the operation of the actuator, but it is not possible to specify to which part the abnormality of the actuator originates. For this reason, it is necessary to specify an abnormal portion of the actuator again after detecting the abnormality, and the maintenance work of the actuator is complicated.

  This invention is made | formed in view of the said situation, and makes it a subject to provide the abnormality detection apparatus which can pinpoint the abnormal site | part of the to-be-driven part driven by a servomotor.

An abnormality detection apparatus according to claim 1 is a servo system comprising a servo motor, a position detector that detects the position of the servo motor, a servo drive that drives the servo motor, and a servo controller that controls the servo drive. An abnormality detection device for detecting an abnormality of a driven part driven by a servo motor, wherein an input part from which position information of the servo motor is input from a position detector, a frequency conversion part for frequency converting the position information, and a frequency A comparison / determination unit that compares the converted amplitude at a predetermined frequency with a threshold value for determining an abnormality of the driven unit, and the input unit receives positional information when an apparatus including the driven unit is operating. acquires, comparison determination unit, when the device is not running, to characterized in that the amplitude to identify the abnormal position of the driven portion from the frequency equal to or larger than the threshold value .

  According to a second aspect of the present invention, in the first aspect, the frequency conversion is a fast Fourier transform.

  According to a third aspect of the present invention, the abnormality detection device according to the first or second aspect further includes a display unit that displays a determination result of the comparison determination unit.

  According to a fourth aspect of the present invention, there is provided the abnormality detection device according to any one of the first to third aspects, wherein at least one of the acceleration, deceleration, speed, and servo motor control gain of the driven unit is determined by the comparison determination unit. It further includes a control unit that lowers according to the result.

  According to a fifth aspect of the present invention, in the abnormality detection device according to any one of the first to fourth aspects, the driven portion is provided in the component mounting apparatus.

  According to the abnormality detection apparatus of the first aspect, the servo motor includes the comparison determination unit that compares the amplitude of the position information of the servo motor at the frequency-converted predetermined frequency with the threshold value for determining the abnormality of the driven unit. The abnormal part of the driven part can be specified based on the position information of the motor. Therefore, the abnormal site | part of a to-be-driven part can be specified, without providing detectors, such as an acceleration sensor, for every site | part of a to-be-driven part. Further, since maintenance can be performed according to the detected abnormal portion of the driven part, the workability of the maintenance work is improved.

  According to the abnormality detection device of the second aspect, since the frequency conversion is performed by the fast Fourier transform, a large amount of servo motor position information can be frequency-converted at high speed, and the calculation time required for the frequency conversion can be shortened. it can.

  According to the abnormality detection apparatus according to the third aspect, since the display unit that displays the determination result of the comparison determination unit is provided, the user of the control device can easily know the maintenance time of the driven unit.

  According to the abnormality detection apparatus of the fourth aspect, the control unit reduces at least one of the acceleration, deceleration, speed, and servo motor control gain of the driven unit according to the determination result of the comparison determination unit. Therefore, for example, when an abnormality occurs in the driven part, the operation of the control device can be continued in a control mode different from that in the normal state.

  According to the abnormality detection apparatus of the fifth aspect, since the driven unit is provided in the component mounting apparatus, for example, the position information of the servo motor is acquired during operation of the component mounting apparatus, and the component mounting apparatus The abnormality of the driven part can be detected during the non-operation. Therefore, for example, it is possible to detect the abnormality of the driven part without stopping the mounting line of the component mounting apparatus by using, for example, the waiting time for transporting the printed circuit board or the waiting time for component replacement.

It is a block diagram which shows an example of a servo system. FIG. 2 is a control block diagram of FIG. 1. It is a figure which shows an example of the relationship between the frequency of position information, and an amplitude. It is a flowchart which shows an example of the control flow of an abnormality detection apparatus. It is a perspective view which shows an example of a component mounting apparatus. It is a front view which shows an example of a component mounting head.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, drawing is a conceptual diagram and does not prescribe | regulate to the dimension of a detailed structure.

(1) Configuration of Servo System FIG. 1 is a configuration diagram showing an example of a servo system. The servo system 100 includes a servo motor 1, a position detector 2 that detects the position of the servo motor 1, a servo drive 3 that drives the servo motor 1, and a servo controller 4 that controls the servo drive 3. .

  The servo motor 1 is provided with a position detector 2 that detects the position of the servo motor 1. The position detector 2 can output position information of the servo motor 1 in synchronization with the rotation of the servo motor 1. it can. As the servo motor 1 and the position detector 2, known servo motors and position detectors employed in numerical controllers can be used. For example, an AC servo motor, an encoder, etc. are mentioned. When an incremental encoder is used as the encoder, the position information is a count value obtained by counting a pulse train corresponding to the rotational displacement amount of the servo motor 1. When an absolute encoder is used, the position information is an output code corresponding to the rotational displacement amount of the servo motor 1. The position information can include various data such as error information of the servo motor 1 and is transmitted to the servo drive 3 via the information transmission path 5 at predetermined intervals.

  The servo drive 3 includes a CPU 30, a memory 31, an input / output interface 32, a communication interface 33, and a power converter 34, which are connected by a bus 35 so that various data and control signals can be transmitted and received. The position information transmitted from the position detector 2 is transmitted to the memory 31 via the input / output interface 32 and the bus 35. The CPU 30 can transmit position information to the servo controller 4 via the bus 35 and the communication interface 33.

  The servo controller 4 includes a CPU 40, a memory 41, a communication interface 42, and a display 4D, which are connected by a bus 43 so that various data and control signals can be transmitted and received. The position information transmitted from the servo drive 3 is transmitted to the memory 41 via the communication interface 42 and the bus 43. In the servo drive 3 and the servo controller 4, the CPUs 30 and 40 and the memories 31 and 41 can perform various calculations of a servo control unit 7 and an abnormality detection device 8 described later. The power converter 34 such as an inverter can drive the servo motor 1 by supplying a motor current based on various calculation results to the servo motor 1 via the power transmission path 5M.

  The communication interfaces 42 and 33 are connected by the information transmission path 5 so that various data and control signals can be transmitted and received, thereby forming a network. The various data includes the position information of the servo motor 1 and the above-described various calculation results. The communication means, protocol, etc. in the information transmission path 5 are not particularly limited. As the network, for example, a servo network can be used. Note that various data and control signals can be transmitted and received by, for example, known serial communication (RS-232C) without configuring a network.

  In addition, input / output data such as position information can be transmitted by direct memory access (DMA). The DMA can directly transmit and receive various data between the input / output device and the memories 31 and 41 without passing through the CPUs 30 and 40. For example, position information can be directly transmitted between the position detector 2 and the memories 31 and 41.

  A driven part 6 is connected to the servomotor 1 so as to be driven. The driven part 6 is not particularly limited as long as it has a mechanism that can be driven by the servomotor 1. For example, a ball screw drive mechanism or the like can be used. In the ball screw driving mechanism, the servo motor 1 rotates the ball screw shaft, and the ball rolls between the ball screw shaft and the ball nut, whereby the rotational motion of the servo motor 1 is converted into a linear motion, and the work table (covered) The driving body) can be guided linearly.

(2) Control of Servo System FIG. 2 is a control block diagram of FIG. When viewed as a control block, the servo system 100 includes a servo control unit 7 and an abnormality detection device 8. By executing a program stored in the memories 31 and 41 shown in FIG. In addition, various calculations of the abnormality detection device 8 can be performed.

(2-1) Servo Control Unit The servo control unit 7 controls the profile generation unit 71 that generates a command for the servo motor 1, a position control unit 72 that controls the position of the servo motor 1, and the speed of the servo motor 1. A speed control unit 73, a current control unit 74 that controls the motor current of the servo motor 1, and a friction compensator 75 that compensates the friction force generated in the driven unit 6 are included, and a position control loop and speed control are included. A triple control loop of a loop and a current control loop is cascaded.

  The profile generation unit 71 calculates a position command for the servo motor 1 based on a command from a host controller (not shown). The command from the host controller includes, for example, a movement command, an acceleration command, a deceleration command, a speed command, and the like to be controlled. The position control unit 72 generates a speed command from the deviation between the position command from the profile generation unit 71 and the position information from the position detector 2. The speed control unit 73 generates a current command (torque command) from the deviation between the speed command from the position control unit 72 and the speed information of the servo motor 1. The speed information of the servo motor 1 can be calculated by differentiating the position information. Moreover, the detection result of the speed detector which is not illustrated can also be used for the speed information of the servo motor 1.

  The current control unit 74 generates a drive signal for the power converter 34 from the deviation between the current command (torque command) from the speed control unit 73 and the motor current of the servo motor 1. As the motor current of the servo motor 1, the detection result of a current detector (not shown) built in the servo drive 3 can be used. The position information from the position detector 2 can be used to adjust the power factor. The drive signal of the power converter 34 can be represented by, for example, a duty ratio that is a ratio between the ON width and the OFF width of a pulse in PWM control. In PWM control, a motor current flows in a corresponding phase when the switching element is ON, and the motor current changes according to the time (ON width) that the switching element is ON. In other words, the motor current increases as the ON width increases, and the motor current decreases as the ON width decreases. The power converter 34 can drive the servo motor 1 by supplying a motor current based on the drive signal generated by the current control unit 74 to the servo motor 1 via the power transmission path 5M. The method of position control, speed control, and current control is not particularly limited. For example, known feedback control such as PID control can be used.

  The position command of the servo motor 1 is input to the friction compensator 75, and the output of the friction compensator 75 is added to the current command (torque command) from the speed control unit 73. For example, when the driven portion 6 is a ball screw drive mechanism, various frictions are generated in the linear guide, the nut of the ball screw, the support bearing of the ball screw, etc. that constitute the drive mechanism. The friction compensator 75 can compensate for these frictional forces generated in the driven part 6. For example, the friction compensator 75 can give a current command (torque command) that cancels the friction force when the moving axis is reversed. That is, the friction compensator 75 gives a current command (torque command) so as to generate a torque pattern opposite to the change in the friction torque when the moving axis is reversed. Thereby, the friction compensator 75 can suppress stick motion. Stick motion is a motion error caused by a delay until the servo control system starts to respond to a change in frictional force when the moving axis is reversed.

  Further, the friction compensator 75 can also suppress lost motion. The lost motion is a motion error generated when the drive mechanism is elastically deformed in a direction opposite to the feed motion by a frictional force. In this case, the friction compensator 75 gives the torque required for elastic deformation to the current command (torque command). In this specification, the control gain used in the friction compensator 75 is referred to as a friction feedforward gain. Note that the suppression of stick motion and the suppression of lost motion are examples, and the compensation target of the friction compensator 75 is not limited to these.

(2-2) Abnormality Detection Device The abnormality detection device 8 includes an input unit 81, a frequency conversion unit 82, a comparison determination unit 83, a display unit 84, a control unit 85, and an abnormality determination table 8T. An abnormality of the driven part 6 to be driven can be detected. The abnormality of the driven part 6 means that the positioning accuracy of the driven part 6 deteriorates due to, for example, a change in viscosity or friction of the driven part 6 due to aged deterioration or failure of the driven part 6. The abnormality of the driven unit 6 includes a case where vibration or abnormal noise occurs in the driven unit 6. Note that these phenomena are examples, and the abnormality of the driven unit 6 is not limited to these phenomena.

  The position information of the servo motor 1 detected by the position detector 2 when the servo motor 1 rotates at a substantially constant speed is input to the input unit 81 at a predetermined sampling cycle. The input position information can be subjected to various filters as necessary. For example, when a band-pass filter is used as the filter, the frequency range of the input position information can be limited in accordance with the frequency characteristics of the driven unit 6 that detects abnormality. The input unit 81 outputs a predetermined number of pieces of position information to the frequency conversion unit 82 as a unit.

  The frequency conversion unit 82 performs frequency conversion on the position information output from the input unit 81 and outputs the frequency information to the comparison determination unit 83. For the frequency transformation, for example, a known method such as Fourier transformation or wavelet transformation can be used. As the number of pieces of position information increases, more accurate frequency conversion can be performed, but the calculation time required for frequency conversion becomes longer. Therefore, it is preferable to use fast Fourier transform (FFT). When fast Fourier transform (FFT) is used for frequency conversion, a large amount of position information can be frequency-converted at high speed, and calculation time required for frequency conversion can be shortened. Further, when performing frequency conversion over a wide frequency band, it is preferable to use wavelet conversion. Since the wavelet transform can enlarge and reduce the basis function, the frequency transform can be efficiently performed over a wide frequency band as compared with the Fourier transform.

  The comparison determination unit 83 compares the amplitude of the position information output from the frequency conversion unit 82 with a threshold value for determining abnormality of the driven unit 6. The threshold value has a first threshold value and a second threshold value greater than the first threshold value. The first threshold value is a state in which the operation of the control device can be continued by the normal control of the servo control unit 7 described above, and refers to a level that alerts the user of the control device. The second threshold value is a state in which it is difficult to continue the operation of the control device by the normal control of the servo control unit 7, and a level at which the control mode of the servo control unit 7 needs to be changed by the control unit 85 to be described later. Say. Three or more threshold values can be provided, and can be arbitrarily set according to the type and control of the control device.

  The threshold value is set in advance for each part of the driven unit 6 by simulation or experiment and is stored in the abnormality determination table 8T. The comparison determination unit 83 reads a threshold value from the abnormality determination table 8T and compares it with the amplitude of the position information according to the part of the driven unit 6 that determines abnormality. Here, an example of a threshold setting method will be described.

  When an abnormality occurs in the driven unit 6, the amplitude of the position information increases in a specific frequency band as compared with the normal state. The frequency band in which the amplitude of the position information increases at the time of abnormality varies depending on the portion of the driven unit 6. Therefore, it is possible to acquire the frequency band in which the amplitude of the position information increases for each part of the driven unit 6 and the amplitude at that time by providing the abnormal state in advance to the driven unit 6 and comparing it with the normal state. it can. At this time, the servo motor 1 may be rotated at a substantially constant speed, for example, at the upper limit of the frequency band to be acquired. The normal state of the driven unit 6 is, for example, the state when the control device is shipped, and the abnormal state of the driven unit 6 is provided by attaching a ball screw that has deteriorated over time, for example, in the case of a ball screw. be able to. An abnormal state can also be provided by loosening the fixing portion of the ball screw.

  FIG. 3 is a diagram illustrating an example of a relationship between frequency and amplitude of position information. The horizontal axis indicates the frequency, and the vertical axis indicates the amplitude of the position information. A curved line 8L1 indicated by a broken line indicates a frequency characteristic when the ball screw driving mechanism is normal, and a curved line 8L2 indicated by a solid line indicates a frequency characteristic when the ball screw driving mechanism is abnormal.

  In the figure, the ball screw has a frequency characteristic in which the amplitude protrudes at a frequency f10 in a normal state (curve 8L1). When abnormality occurs in the ball screw due to aging deterioration of the ball screw, loosening of the fixing portion, or the like, the frequency at which the amplitude protrudes shifts to the frequency f11 (curve 8L2). In the case of a ball screw, since the frequency range f12 to f13 in which the amplitude protrudes is narrower than that of a table guide, which will be described later, abnormality determination of the ball screw is performed at a frequency f11 that is substantially between the frequencies f12 and f13. The comparison determination unit 83 compares the amplitude A11 of the position information at the frequency f11 with the first threshold A12, and determines that the ball screw is abnormal when the amplitude A11 of the position information is equal to or greater than the first threshold A12. The comparison determination unit 83 determines that the ball screw is normal when the amplitude A11 of the position information is smaller than the first threshold A12. In the figure, the amplitude of position information when the ball screw is normal is indicated by A11, and the amplitude of position information when the ball screw is abnormal is indicated by A11 '. In addition, it is possible to determine the abnormality of the ball screw for the second threshold A13 as well as the first threshold A12.

  The table guide for guiding the work table has a frequency characteristic in which the amplitude of the position information gradually increases in the frequency range f21 to f22 during normal operation (curve 8L1). For example, if the lost motion during the movement of the work table increases due to the pressure loss of the nut or the like, vibration occurs with the movement of the work table. Thus, when abnormality occurs in the table guide, the amplitude of the position information increases in the frequency ranges f21 to f22 (curve 8L2). Since the frequency range f21 to f22 in which fluctuations in the position information amplitude appear is wider than that of the ball screw, the table guide abnormality determination is performed at frequencies f21 and f22 and a frequency f20 substantially between these frequencies. When at least one of the amplitude A20 of the position information at the frequency f20, the amplitude A21 of the position information at the frequency f21, and the amplitude A22 of the position information at the frequency f22 is greater than or equal to the first threshold A23, the comparison determination unit 83 Judged to be abnormal. The comparison determination unit 83 determines that the table guide is normal when all of the amplitudes A20, A21, and A22 of the position information are smaller than the first threshold A23. In the figure, the amplitude of position information when the table guide is normal is indicated by A20, A21, and A22, and the amplitude of position information when the table guide is abnormal is indicated by A20 ', A21', and A22 '. It should be noted that it is possible to determine the abnormality of the table guide for the second threshold A24 as well as the first threshold A23.

  The display unit 84 displays the determination result of the comparison determination unit 83 on the display 4D. The display 4D is an output device such as a cathode ray tube, a liquid crystal display, or a printer, and can be substituted by using an operation screen of the control device. The display unit 84 can display at least the abnormal part of the driven unit 6 on the display 4D based on the determination result of the comparison determination unit 83. The display unit 84 can also display on the display 4D the frequency when the abnormality of the driven unit 6 is determined, the amplitude of the position information, and the like. The display method of the determination result is not particularly limited. For example, two-dimensional or three-dimensional drawing or text display may be used, and a figure, a symbol, a table, an illustration, a photograph, a moving image, or the like may be used. In this embodiment, since the display unit 84 that displays the determination result of the comparison determination unit 83 is provided, the user of the control device can easily know the maintenance time of the driven unit 6.

  The control unit 85 can reduce at least one of the acceleration, deceleration, speed, and control gain of the servo motor 1 of the driven unit 6 according to the determination result of the comparison determination unit 83. In order to decrease the acceleration, deceleration, and speed of the driven unit 6, the acceleration command, deceleration command, and speed command of the profile generation unit 71 are changed. Examples of the control gain of the servo motor 1 include a position control gain in the position control unit 72, a speed control gain in the speed control unit 73, a current control gain in the current control unit 74, and a friction feed forward gain in the friction compensator 75. , At least one of these control gains can be reduced. Acceleration, deceleration, speed, and control gain may all be reduced at the same rate or may be reduced at different rates.

  In the present embodiment, the control unit 85 can reduce at least one of the acceleration, deceleration, speed, and control gain of the servo motor 1 of the driven unit 6 according to the determination result of the comparison determination unit 83. Therefore, for example, when an abnormality occurs in the driven unit 6, the operation of the control device can be continued in a control mode different from the normal mode.

(2-3) Control Flow of Abnormality Detection Device FIG. 4 is a flowchart illustrating an example of a control flow of the abnormality detection device. When the servo motor 1 is rotating at a substantially constant speed, position information of the servo motor 1 is input by the input unit 81 at a predetermined sampling period (step S1). The frequency information of the position of the servo motor 1 is converted by the frequency converter 82 (step S2). The comparison determination unit 83 compares the amplitude A11 of the position information with the first threshold value A12 (step S3). When the amplitude A11 of the position information is greater than or equal to the first threshold value A12, the ball screw is abnormally displayed on the display unit 84 (step S4). Next, the comparison determination unit 83 compares the amplitude A11 of the position information with the second threshold value A13 (step S5). When the amplitude A11 of the position information is equal to or greater than the second threshold A13, the control unit 85 decreases at least one of the acceleration, deceleration, speed, and control gain of the servo motor 1 of the driven unit 6 (step S6). .

  The comparison determination unit 83 compares the amplitudes A20, A21, and A22 of the position information with the first threshold value A23 (step S7). When at least one of the amplitudes A20, A21, A22 of the position information is greater than or equal to the first threshold value A23, the display unit 84 displays an abnormal table guide (step S8). Next, the comparison determination unit 83 compares the amplitudes A20, A21, and A22 of the position information with the second threshold value A24 (step S9). When at least one of the amplitudes A20, A21, A22 of the position information is greater than or equal to the second threshold A24, the control unit 85 causes at least one of the acceleration, deceleration, speed, and control gain of the servomotor 1 of the driven unit 6 to be controlled. One is lowered (step S10). Then, this routine is finished once.

  Although all of steps S1 to S10 shown in the figure can be executed at a time, a part of steps S1 to S10 is executed while the control device is operating (on-line), and the rest of the steps are performed by the control device. It can also be executed during non-operation (offline). For example, only the step S1 is executed during operation of the control device, and the position information of the servo motor 1 is acquired. By executing the remaining steps S2 to S10 while the control device is not operating, the calculation load of the control device can be distributed. Further, the position information of the servo motor 1 can be transmitted to the host controller of the control device, and the host controller can execute the same arithmetic processing as steps S1 to S10.

  In the present embodiment, since the comparison determination unit 83 that compares the amplitude of the position information of the servomotor 1 at the predetermined frequency after frequency conversion and the threshold value for determining abnormality of the driven unit 6 is provided, the position of the servomotor 1 The abnormal part of the driven part 6 can be specified based on the information. Therefore, an abnormal site of the driven unit 6 can be specified without providing a detector such as an acceleration sensor for each site of the driven unit 6. Further, since maintenance can be performed according to the detected abnormal part of the driven part 6, the workability of the maintenance work is improved.

  Further, when the amplitude of the position information of the servo motor 1 is equal to or greater than the first threshold value, the display unit 84 displays an abnormality of the driven unit 6, so that the user of the control device can be alerted. Furthermore, when the amplitude of the position information of the servo motor 1 is greater than or equal to the second threshold, the operation of the control device can be continued according to the control mode of the servo control unit 7 that is different from the normal mode.

(Deformation)
The abnormality detection device 8 can also be provided in the servo drive 3. The profile generation unit 71, the position control unit 72, the speed control unit 73, the current control unit 74, and the friction compensator 75 of the servo control unit 7 can be appropriately disposed between the servo drive 3 and the servo controller 4. 1 and 2, the servo system 100 includes one servo motor 1, one position detector 2, and one servo drive 3, but a plurality of servo motors 1, position detector 2, and servo drive 3 are provided for each axis. And can be controlled simultaneously. The acceleration information, deceleration information, and speed information of the servo motor 1 are based on the position information, and the current command (torque command) of the servo motor 1 is generated by feeding back the position information and speed information of the servo motor 1. Therefore, frequency conversion can also be performed using at least one of acceleration information, deceleration information, speed information, and current command (torque command) of the servo motor 1 instead of the position information of the servo motor 1.

(3) Driven part The driven part 6 can be a driven part of a component mounting apparatus, for example. FIG. 5 is a perspective view showing an example of a component mounting apparatus. FIG. 6 is a front view showing an example of a component mounting head.

  As shown in FIG. 5, the component mounting apparatus 9 includes a component supply device 970, a board transfer device 960, and a component transfer device 980. The component supply device 970 is configured by arranging a plurality of cassette type feeders 971 on a base frame 990 in parallel. The cassette type feeder 971 includes a main body 972 detachably attached to the base frame 990, a supply reel 973 provided at the rear portion of the main body 972, and a component take-out portion 974 provided at the tip of the main body 972. The supply reel 973 is wound and held with a long and narrow tape in which the electronic component P is sealed at a predetermined pitch, and this tape is pulled out at a predetermined pitch by a sprocket (not shown). Are sent sequentially.

  A component camera 975 as an imaging unit 950 that detects the holding position of the electronic component P is provided between the component supply device 970 and the substrate transfer device 960. The component camera 975 can detect a positional shift and an angular shift of the electronic component P sucked by a suction nozzle 918 described later with respect to the suction nozzle 918. The detection result of the positional deviation and the angular deviation can be used when correcting the mounting position of the electronic component P.

  The board transport device 960 transports a printed circuit board in the X-axis direction shown in FIG. 5 and is of a so-called double conveyor type in which two rows of first transport devices 961 and second transport devices 962 are arranged side by side. The first transport device 961 and the second transport device 962 have a pair of guide rails 964a, 964b, 965a, 965b arranged parallel to each other on the base 963 in parallel with each other, and these guide rails 964a, 964b. , 965a and 965b, a pair of conveyor belts (not shown) for supporting and transporting the printed circuit boards, respectively, are arranged opposite to each other. Further, the substrate transport device 960 is provided with a clamp device (not shown) that pushes up and clamps the printed circuit board transported to a predetermined position, and the printed circuit board is positioned and fixed at the mounting position by the clamp device.

  The component transfer device 980 is of the XY robot type, is mounted on the base frame 990 and disposed above the substrate transfer device 960 and the component supply device 970, and is moved in the Y-axis direction by the Y-axis servo motor 911. Y-axis slider 912 is provided. As shown in FIG. 6, an X-axis slider 913 is guided by the Y-axis slider 912 so as to be movable in the X-axis direction orthogonal to the Y-axis direction.

  The X-axis slider 913 can move to the Y-axis slider 912 via a pair of guide rails 912 a that are fixed to the Y-axis slider 912 and extend in the X-axis direction, and a pair of guide blocks 913 a that are fixed to the X-axis slider 913. Is held in. An X-axis servo motor (not shown) is fixed to the X-axis slider 913, and a ball screw shaft 912b extending in the X-axis direction is connected to the output shaft of the X-axis servo motor. The ball screw shaft 912b is screwed to a ball nut 913b fixed to the X-axis slider 913 via a ball (not shown). Thus, when the X-axis servo motor rotates, the ball screw shaft 912b rotates, and the X-axis slider 913 is guided by the guide rail 912a via the ball nut 913b and moves in the X-axis direction.

  On the X-axis slider 913, a component mounting head 910 that attracts the electronic component P and mounts it on the printed circuit board is mounted. As shown in FIG. 6, the component mounting head 910 includes an R-axis motor 915, an index shaft 916, a nozzle holder 917, a suction nozzle 918, a θ-axis motor 919, a Z-axis motor 920, an image pickup means 950 having a CCD camera 921, and the like. It is constituted by.

  The X-axis slider 913 is provided with first and second frames 925 and 926 extending in the horizontal direction so as to be separated from each other in the vertical direction (Z-axis direction), and an R-axis motor 915 is fixed to the first frame 925. Yes. The output shaft of the R-axis motor 915 is connected to an index shaft 916 that is rotatably supported around the vertical axis AL (R-axis direction). A rotating body 928 having a driven gear 927 and a θ-axis gear 929 is rotatably supported on the index shaft 916. A cylindrical nozzle holder 917 constituting a revolver head is fixed to the lower end portion of the index shaft 916.

  A plurality of suction nozzles 918 are held by the nozzle holder 917 so as to be movable in the Z-axis direction on a circumference concentric with the vertical axis AL. Each suction nozzle 918 is attached to the lower end of a nozzle spindle 933 supported by a nozzle holder 917 so as to be slidable in the Z-axis direction. A large diameter portion 933 a is formed at the lower end portion of the nozzle spindle 933, and a nozzle gear 934 is fixed to the upper end portion of the nozzle spindle 933. A compression spring 935 is provided between the nozzle gear 934 and the nozzle holder 917. The compression spring 935 urges the nozzle spindle 933 and the suction nozzle 918 upward, and the large-diameter portion 933a is formed on the lower surface of the nozzle holder 917. , The upward movement of the nozzle spindle 933 and the suction nozzle 918 is restricted. Further, a negative pressure is supplied to each suction nozzle 918 from a suction nozzle driving device (not shown) via a nozzle spindle 933. As a result, each suction nozzle 918 can suck the electronic component P at its tip 918a.

  A cylindrical reflector 931 capable of reflecting light is fixed to the center of the lower end of the nozzle holder 917. Therefore, the nozzle holder 917 and the reflector 931 are rotated around the vertical axis AL together with the index shaft 916. As a result, when the R-axis motor 915 is rotated, the nozzle holder 917 holding the plurality of suction nozzles 918 can be rotated around the vertical axis AL (R-axis direction) via the index shaft 916. The suction nozzle 918 can be sequentially indexed to the mounting station.

  A θ-axis motor 919 is fixed to the first frame 925, and a drive gear 936 is fixed to the output shaft of the θ-axis motor 919. The drive gear 936 is meshed with a driven gear 927 on a rotating body 928 that is rotatably supported by the index shaft 916. A θ-axis gear 929 is formed on the rotating body 928 over a predetermined length in the axial direction, and the θ-axis gear 929 is slidably engaged with each nozzle gear 934 fixed to the nozzle spindle 933. ing. Accordingly, when the θ-axis motor 919 is rotated, all the suction nozzles 918 can be rotated with respect to the nozzle holder 917 via the drive gear 936, the driven gear 927, the θ-axis gear 929, and the nozzle gear 934.

  A Z-axis motor 920 is fixed to the first frame 925, and a ball screw shaft 937 is connected to the output shaft of the Z-axis motor 920. The ball screw shaft 937 is supported by a bearing 938 fixed to the first frame 925 and a bearing 939 fixed to the second frame 926 so as to be rotatable about an axis parallel to the vertical axis AL. A ball nut 940 that converts the rotational motion of the Z-axis motor 920 into linear motion is screwed onto the ball screw shaft 937 via a ball (not shown). The ball nut 940 is fixed to a nozzle lever 941 that is slidably guided in a vertical direction by a guide 942 that is fixed to the first and second frames 925 and 926 and extends in the vertical direction.

  The nozzle lever 941 is provided with a pressing portion 941a that abuts the upper end of the nozzle spindle 933 indexed to the mounting station and presses the nozzle spindle 933 downward in the Z-axis direction. Accordingly, when the Z-axis motor 920 is rotated, the ball screw shaft 937 is rotated, and the nozzle lever 941 is guided by the guide 942 via the ball nut 940 and moves up and down. When the nozzle lever 941 moves up and down, the nozzle spindle 933 and the suction nozzle 918 corresponding to the pressing portion 941a can be moved up and down.

  The pressing portion 941a of the nozzle lever 941 has a predetermined width W1 around the mounting station in the rotation direction of the nozzle holder 917, and the suction nozzle 918 is positioned in a predetermined angular range before and after the mounting station. The pressing portion 941a can be brought into contact with the upper end of the nozzle spindle 933 of the suction nozzle 918. Accordingly, the suction nozzle 918 can be moved in the vertical direction (Z-axis direction) during the rotation operation of the nozzle holder 917 in a predetermined angular range before and after the mounting station.

  A support bracket 943 is suspended from the second frame 926, and the electronic component sucked by the tip end portions 918 a of the two suction nozzles 918 indexed to the station immediately before and immediately after the nozzle holder 917 mounting station is mounted on the support bracket 943. One CCD camera 921 that acquires a two-dimensional image of P is fixed. The CCD camera 921 can acquire a two-dimensional image of the electronic component P sucked by the tip 918a of the suction nozzle 918 by the light reflected by the reflector 931.

  The imaging case main body 945 is fixed to the side of the support bracket 943 corresponding to the suction nozzle 918, and the vertical axis AL is centered on the circular arc so as to surround the nozzle holder 917 on the side of the imaging case main body 945 facing the reflector 931. An arc-shaped wall surface is formed over the stations immediately before and after the nozzle holder 917 mounting station. A plurality of irradiation bodies 946 made of LEDs that irradiate light toward the reflector 931 are mounted on the arc-shaped wall surface of the imaging case body 945.

  Next, the operation of mounting the electronic component P on the printed circuit board by the component mounting apparatus 9 having the above configuration will be described. First, based on a command from a control device (not shown), the conveyor belt of the board transport device 960 is driven, and the printed circuit board is guided to the guide rails 964a and 964b (965a and 965b) and transported to a predetermined position. Then, the printed circuit board is pushed up and clamped by the clamping device, and is positioned and fixed at a predetermined position. Subsequently, when the Y-axis servo motor 911 and the X-axis servo motor (not shown) are driven, the Y-axis slider 912 and the X-axis slider 913 are moved, and the component mounting head 910 moves to the component extraction unit 974 of the component supply device 970. Moved. Subsequently, the R-axis motor 915 is rotated by the control device, whereby the nozzle holder 917 is rotated, and the nozzle spindle 933 mounted with a predetermined suction nozzle 918 is indexed below the pressing portion 941a of the nozzle lever 941. .

  Further, when the Z-axis motor 920 is rotated forward by the control device, the nozzle lever 941 is pushed downward against the urging force of the compression spring 935, and the tip end portion of the suction nozzle 918 is passed through the nozzle spindle 933. 918a is pushed down to a position approaching the electronic component P conveyed to the component take-out portion 974. In this state, a negative pressure is supplied to the suction nozzle 918 from a suction nozzle driving device (not shown), and the electronic component P is sucked and held on the tip portion 918a of the suction nozzle 918. Thereafter, when the Z-axis motor 920 is reversed, the nozzle lever 941 is moved upward, and the suction nozzle 918 is pushed up to the rising end position by the urging force of the compression spring 935. By repeating such an operation, the electronic components P are sucked and held by the plurality of suction nozzles 918, respectively.

  Subsequently, when the Y-axis servo motor 911 and the X-axis servo motor (not shown) are driven, the Y-axis slider 912 and the X-axis slider 913 are moved, and the component mounting head 910 is moved above the mounting position of the printed circuit board. The Next, the rotation of the θ-axis motor 919 controls the electronic component P sucked and held at the tip end portion 918a of the suction nozzle 918 indexed to the mounting station of the nozzle holder 917 to a predetermined posture, and also the Z-axis motor 920. , The nozzle lever 941 is pushed downward against the urging force of the compression spring 935, and is pushed down until the electronic component P at the tip 918a of the suction nozzle 918 is mounted on the printed circuit board. . Thereafter, when the Z-axis motor 920 is reversed, the nozzle lever 941 is moved upward, and the suction nozzle 918 is pushed up to the uppermost end by the urging force of the compression spring 935.

  The electronic component P is mounted on the printed circuit board by the lowering operation of the suction nozzle 918 indexed to such a mounting station. During the mounting operation of the electronic component P, the station immediately before and after the mounting station is mounted. The side images of the tip portions 918a of the two suction nozzles 918 that have been stopped are acquired by the imaging unit 950, and the two acquired side images are input to the image recognition unit and recognized.

  The abnormality detection device of the present invention can detect abnormality of the Y-axis slider 912, the ball screw shaft 912b of the X-axis slider 913, the ball nut 913b, the guide rail 912a, and the guide block 913a, for example. The abnormality detection device can also detect an abnormality in the ball screw shaft 937, the bearings 938 and 939, the ball nut 940, and the guide 942 connected to the output shaft of the Z-axis motor 920. In particular, when the component mounting head 910 moves to the component extraction unit 974 of the component supply device 970, the abnormality detection device may detect an abnormality of the driven unit. At this time, since the Y-axis slider 912 and the X-axis slider 913 can move at a high speed at a substantially constant speed, the position information of the Y-axis servo motor 911 that drives them and the X-axis servo motor (not shown) is in a wide frequency band. Over a stable range.

  Furthermore, the abnormality detection apparatus of the present invention can acquire the position information of the servo motor during operation of the component mounting apparatus 9 and detect abnormality of the driven part while the component mounting apparatus 9 is not operating. it can. Therefore, for example, it is possible to detect the abnormality of the driven part without stopping the mounting line of the component mounting apparatus 9 by using, for example, the waiting time for transporting the printed circuit board or the waiting time for component replacement.

(4) Others The present invention is not limited to the embodiment described above and shown in the drawings, and can be implemented with appropriate modifications within a range not departing from the gist.

1: Servo motor 2: Position detector 3: Servo drive 4: Servo controller 6: Driven unit 8: Abnormality detection device 81: Input unit 82: Frequency conversion unit 83: Comparison determination unit 84: Display unit 85: Control unit 9 : Component mounting apparatus 100: Servo system

Claims (5)

In a servo system comprising a servo motor, a position detector that detects the position of the servo motor, a servo drive that drives the servo motor, and a servo controller that controls the servo drive, the servo motor is driven by the servo motor. An abnormality detection device for detecting an abnormality of a driven part,
The position information of the servo motor is input from the position detector, the frequency converter that converts the frequency of the position information, the amplitude at the predetermined frequency subjected to the frequency conversion and the abnormality of the driven part are determined. A comparison determination unit that compares the threshold value,
The input unit acquires the position information when an apparatus including the driven unit is operating,
The abnormality detection device, wherein the comparison determination unit identifies an abnormal portion of the driven unit from a frequency at which the amplitude is equal to or greater than the threshold when the device is not operating .   The abnormality detection device according to claim 1, wherein the frequency conversion is a fast Fourier transform.   The abnormality detection device according to claim 1, further comprising a display unit that displays a determination result of the comparison determination unit.   4. The control unit according to claim 1, further comprising a control unit that reduces at least one of acceleration, deceleration, speed, and control gain of the servo motor of the driven unit according to a determination result of the comparison determination unit. The abnormality detection apparatus according to item 1. The abnormality detection apparatus according to claim 1, wherein the driven part is provided in a component mounting apparatus.

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