JP2018205895A - Movement precision monitoring system and rotation table provided with movement precision monitoring function, machine tool and nc apparatus - Google Patents

Abstract

To provide a movement precision monitoring system capable of appropriately monitoring and diagnosing a reduction in movement precision in an actual operation in a timely manner.SOLUTION: A movement precision monitoring system 2 includes: a drive-shaft-side sensor 10 that measures a position or displacement of a drive shaft 4 which is rotated and moved; a driven-unit-side sensor 12 that measures a position or displacement of a driven unit 6 which is rotated or moved on a predetermined trajectory by drive torque from the drive shaft 4 via a drive force transmitting unit 8; a differential detecting unit 22 that forms differential data between the displacement of the drive shaft 4 and the displacement of the driven unit 6 having a transmission gear ratio of the drive force transmitting unit 8 taken into consideration on the basis of measured values of the drive-shaft-side sensor 10 and of the driven-unit-side sensor 12 at a timing defined in a predetermined manner; and a monitoring control unit 24 that forms information on a movement precision of the driven unit 6 on the basis of a change in the differential data or a change in computed value using the differential data. A rotation table provided with a movement precision monitoring function, a machine tool and an NC apparatus are also provided.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a movement accuracy monitoring system for a driven part that rotates or moves on a predetermined track by a driving torque of a driving shaft via a driving force transmission part, a rotary table having a movement accuracy monitoring function, a machine tool, and It relates to the NC device.

  For example, a gear transmission mechanism in which gears attached to a drive shaft and a driven shaft (driven portion) mesh with each other is widely used as a driving force transmission portion that rotates a driven portion by the driving torque of the driving shaft. In such a gear transmission mechanism, since the driving force is transmitted by the contact surface of the gear, if the contact surface of the gear is worn out over many years, the backlash will increase or the slippage will be worsened. Positioning accuracy and rotational speed accuracy may be deteriorated.

  It is important to accurately monitor such a decrease in positioning accuracy and rotational speed accuracy on the driven shaft side, and in order to cope with this, for example, a transmission error between both gears of the drive shaft and the driven shaft is detected. A gear test has been proposed (see, for example, Patent Document 1).

Japanese Patent Publication No. Hei 4-77259

  Patent Document 1 describes that a rotary encoder is coupled to a drive shaft and a driven shaft to which gears meshing with each other are attached, and a transmission error between both gears is detected based on a phase difference between the two. However, in order to perform this test, it is necessary to remove the gear transmission mechanism from the apparatus, and it is difficult to frequently check for a decrease in the movement accuracy of the apparatus in operation. In this test, it is possible to detect transmission errors due to gear wear, but there are other factors that reduce the accuracy of movement of the driven shaft when the gear transmission mechanism is actually installed. Yes, it is impossible to accurately monitor the decrease in movement accuracy in actual operation.

  Accordingly, an object of the present invention is to provide a timely and accurate reduction in movement accuracy in actual operation of a driven part that rotates or moves on a predetermined track by a driving torque of a driving shaft via a driving force transmission part. It is an object of the present invention to provide a moving accuracy monitoring system capable of monitoring and diagnosing, and a rotary table, a machine tool and an NC apparatus provided with the moving accuracy monitoring function.

In order to solve the above problems and achieve the object of the present invention, a movement accuracy monitoring system according to one embodiment of the present invention includes:
A drive shaft side sensor for measuring the position or movement amount of the drive shaft that rotates and moves;
A driven part side sensor for measuring the position or amount of movement of the driven part that rotates or moves on a predetermined track by the driving torque of the drive shaft via the driving force transmission part;
Based on the measured values of the driving shaft side sensor and the driven unit side sensor at the timing determined in a predetermined mode, the amount of movement of the driving shaft taking into account the transmission ratio in the driving force transmission unit and the driven unit A difference detection unit that forms difference data with the movement amount;
A monitoring control unit that forms information on the movement accuracy of the driven unit based on a change in the difference data or a change in an operation value using the difference data;
Is provided.

  A turntable according to one embodiment of the present invention includes the above movement accuracy monitoring system.

  A machine tool according to one embodiment of the present invention includes the above movement accuracy monitoring system.

  An NC device according to one embodiment of the present invention includes the difference detection unit and the monitoring control unit.

  According to the movement accuracy monitoring system, the rotary table, the machine tool, and the NC device of the above embodiment, the driven unit that rotates or moves on the predetermined track by the driving torque of the driving shaft via the driving force transmission unit, It is possible to accurately monitor and diagnose a decrease in movement accuracy in actual operation in a timely manner.

It is a figure which shows typically the example of arrangement | positioning of the drive shaft side sensor and driven part side sensor in case a to-be-driven part rotationally moves by the driving torque of a drive shaft via a driving force transmission part. An arrangement example of the drive shaft side sensor and the driven unit side sensor when the driven unit moves on a predetermined track (in this case, movement in a linear direction) by the driving torque of the driving shaft via the driving force transmission unit is shown. It is a figure typically. It is a figure which shows typically an example of the connection from a drive shaft side sensor and a to-be-driven part side sensor to a monitoring system control apparatus. It is a block diagram which shows typically the control structure of the movement precision monitoring system which concerns on the 1st Embodiment of this invention. It is a block diagram which shows typically the control structure of the movement precision monitoring system which concerns on the 2nd Embodiment of this invention. It is a block diagram which shows typically the control structure of the movement precision monitoring system which concerns on the 3rd Embodiment of this invention. It is the graph which showed the relationship between the cumulative movement length or cumulative operation period (X-axis), and difference value (Y-axis) using the measurement example by a drive-axis side sensor and a to-be-driven part side sensor. It is a figure which shows typically the other example of the connection to a monitoring system control apparatus from a drive shaft side sensor and a to-be-driven part side sensor. It is a figure showing typically a turntable concerning one embodiment of the present invention. It is a figure showing typically a machine tool concerning one embodiment of the present invention. It is a figure showing typically the NC device concerning one embodiment of the present invention.

  Hereinafter, various embodiments and examples for carrying out the present invention will be described with reference to the drawings. In the drawings, members corresponding to those having the same function are denoted by the same reference numerals. Considering the ease of explanation or understanding of the main points, the embodiments (examples) are shown separately for convenience, but partial replacement or combination of the configurations shown in different embodiments (examples) is possible. In the following description of the second embodiment (other examples), description of matters common to the first embodiment (one example) is omitted, and only different points will be described. In particular, the same operation and effect of the same configuration will not be sequentially referred to for each embodiment (example). In addition, the present invention is not limited to the following embodiments and examples.

(Arrangement of drive shaft side sensor and driven part side sensor)
The movement accuracy monitoring system according to the present invention includes a drive shaft side sensor that measures the position or movement amount of a rotationally moving drive shaft, and a drive force transmission unit to rotate or move on a predetermined trajectory. And a driven unit side sensor for measuring the position or movement amount of the driven unit that performs the above-described operation. Note that “via the driving force transmission unit” means that the driving force and the driving torque are transmitted by physical contact of the mechanical elements of the driving force transmission unit. First, the arrangement of the drive shaft side sensor and the driven unit side sensor will be described.

<When the driven part rotates>
First, with reference to FIG. 1, an arrangement example in the case where the driven part rotates is described. FIG. 1 schematically shows an arrangement example of the drive shaft side sensor 10 and the driven portion side sensor 12 when the driven portion 6 is rotationally moved by the driving torque of the drive shaft 4 via the driving force transmission portion 8. FIG.

In the example shown in FIG. 1, a drive motor (electric motor) 30 that rotates the drive shaft 4 is provided. The drive shaft 4 may be a rotating shaft of the driving motor 30 or an individual member connected to the rotating shaft of the driving motor 30. In addition, a worm gear type driving force transmission mechanism including a worm 4A provided on the driving shaft 4 and a worm wheel 6A attached to the driven portion 6 is shown as the driving force transmission portion 8.
Since such a worm gear type driving force transmission mechanism can provide a large reduction ratio, it can be used, for example, for a rotary table (an inclined stage or the like) that is installed in addition to a machine tool and increases the degree of freedom of processing. The worm gear type rotary table is widely used because it can rotate a small and heavy work piece and can relatively reduce backlash compared to a direct drive rotary table or the like.

  In the example shown in FIG. 1, the worm 4 </ b> A provided on the drive shaft 4 that is rotated by the drive torque of the drive motor 30 can rotate in both directions as indicated by an arrow A. Correspondingly, the driven portion 6 to which the worm wheel 6A is attached is decelerated at a predetermined speed ratio as indicated by an arrow B and rotates in both directions. This driven part 6 can be used as a rotary table for rotating a workpiece.

A drive motor rotary encoder 32 is attached to the rear end side of the rotation shaft of the drive motor 30 of the drive shaft 4. With this rotary encoder 32 for drive motor, the rotational position and amount of the drive shaft 4 of the drive motor 30 can be accurately measured.
Further, the driven portion 6 has an encoder scale 12B provided with slits in an arc shape at a constant angle pitch. Further, an encoder head 34A composed of a light source and a photoelectric element is installed at the rotational radius position of the encoder scale 12B. The encoder head 34A and the encoder scale 12B constitute a wheel drive control rotary encoder 34. With this wheel drive control rotary encoder 34, the rotational position and the amount of rotation of the driven part 6 can be accurately measured.

  The drive motor 30 can be feedback-driven based on measurement data from the drive motor rotary encoder 32 and the wheel drive control rotary encoder 34.

Further, the drive shaft side sensor 10 of the movement accuracy monitoring system 2, which is a rotary encoder, is attached to the end of the drive shaft 4 opposite to the drive motor 30. This drive shaft side sensor (rotary encoder) 10 can accurately measure the rotational position and the rotational amount of the drive shaft 4 of the drive motor 30.
The driven portion 6 has the encoder scale 12B described above, and an encoder head 12A composed of a light source and a photoelectric element is installed at a rotational radius position of the encoder scale 12B (a position different from the encoder head 34A in the circumferential direction). Has been. The encoder head 12A and the encoder scale (rotary encoder) 12B constitute a driven portion side sensor 12 of the movement accuracy monitoring system 2, which is a rotary encoder. With this driven part side sensor (rotary encoder) 12, the rotational position and the rotational amount of the driven part 6 can be accurately measured.

  In the example shown in FIG. 1, the same encoder scale 12B is used in the wheel drive control rotary encoder 34 and the driven portion side sensor (rotary encoder) 12. However, the two rotary encoders may have individual encoder scales. it can. In the example shown in FIG. 1, a drive motor side rotary encoder 32 for driving control of the drive motor 30 and a rotary encoder 34 for wheel drive control are separately provided from a drive shaft side sensor (rotary encoder) 10 for monitoring movement accuracy and driven. However, the present invention is not limited to this, and at least one of the drive shaft side sensor (rotary encoder) 10 and the driven part side sensor (rotary encoder) 12 is connected to the drive motor 30. It can also be shared with the rotary encoders 32 and 34 for driving control.

  The rotary encoder used in the movement accuracy monitoring system 2 may be an incremental encoder or an absolute encoder. In the case of an incremental encoder, it is necessary to reset to zero once before starting measurement or to turn on / off the power. In the case of an absolute encoder, the encoder value at the start of measurement is stored, and the calculation is performed by always subtracting the value. In the case of an absolute encoder, the absolute position of each mechanical element of the drive shaft 4, the driven part 6 or the driving force transmission part 8 can also be detected.

<When the driven part moves on a predetermined trajectory>
Next, with reference to FIG. 2, an arrangement example in which the driven part moves in a linear direction will be described as an example of the case where the driven part moves on a predetermined trajectory. FIG. 2 shows the driving shaft side sensor 10 ′ and the driven portion side sensor 12 ′ when the driven portion 6 ′ moves in the linear direction by the driving torque of the driving shaft 4 ′ via the driving force transmission portion 8 ′. It is a figure which shows the example of arrangement | positioning typically.

  The example shown in FIG. 2 also includes a drive motor (electric motor) 30 ′ that rotates the drive shaft 4 ′. Further, as the driving force transmission unit 8 ′, any mechanism that converts a rotational movement, such as a ball screw mechanism, a rack and pinion mechanism, a crank mechanism, and a cam mechanism, into a movement on a predetermined track can be used. In the example shown in FIG. 2, the drive shaft 4 ′ can rotate in both directions as indicated by an arrow C by the drive torque of the drive motor 30 ′. Correspondingly, the rotational movement is converted into a linear movement by the driving force transmission section 8 ′, and the driven section 6 ′ moves linearly in both directions as indicated by an arrow D.

In the example shown in FIG. 2, a drive shaft side sensor 10 ′ composed of a rotary encoder is attached to a drive shaft 4 ′ that rotates with the drive torque of the drive motor 30 ′. In addition, it can be shared with the rotary encoder for drive control of drive motor 30 ', and can also be provided separately.
Further, a driven unit side sensor 12 ′ composed of a linear encoder is provided along the moving direction of the driven unit 6 ′. In addition, it can be shared with the linear encoder for drive control of drive motor 30 ', and can also be provided separately.

  As described above, even when the driven unit 6 ′ moves on a predetermined trajectory, the movement according to any embodiment of the present invention described below is the same as when the driven unit 6 rotates. The accuracy monitoring system 2 can be applied.

In the example of FIGS. 1 and 2, a drive motor (electric motor) that rotates the drive shaft 4 is provided. However, the present invention is not limited to this, and an arbitrary rotational drive source including a hydraulic motor, an air motor, and a prime mover. Can be used.
In the example of FIG. 1, a worm gear composed of a worm and a worm wheel is used as the driving force transmission unit 8. However, the present invention is not limited to this, and other arbitrary gears such as spur teeth and bevel teeth can be used. It can be used, and a planetary gear can also be used.

  In the example of FIG. 1, a rotary encoder is used as the drive shaft side sensor and the driven unit side sensor. However, the present invention is not limited to this, and any other digital rotation that transmits a digital signal at a predetermined interval. A sensor can also be used. Furthermore, an analog sensor such as a potentiometer that outputs measurement values continuously can be used.

(Example of connection from the drive shaft side sensor and the driven unit side sensor to the monitoring system control device)
Next, the electrical connection from the drive shaft side sensor and the driven unit side sensor to the monitoring system control device will be described with reference to FIG. 3, taking the case shown in FIG. 1 as an example. FIG. 3 is a diagram schematically illustrating an example of connection from the drive shaft side sensor 10 and the driven unit side sensor 12 to the monitoring system control device 20.

As shown in FIG. 3, driven to perform rotational movement by the driving torque of the driving shaft 4 via the driving shaft side sensor 10 that measures the position or moving amount of the driving shaft 4 that rotates and the driving force transmission unit 8. A driven unit side sensor 12 that measures the position or movement amount of the unit 6 is electrically connected to the monitoring system control device 20.
The monitoring system control device 20 shifts the driving force transmission unit 8 based on the measured values of the drive shaft side sensor (rotary encoder) 10 and the driven unit side sensor (rotary encoder) 12 at the timing determined in a predetermined manner. Based on the difference detection unit 22 that forms difference data between the movement amount of the drive shaft 4 and the movement amount of the driven unit 6 in consideration of the ratio, and the change of the difference data or the calculation value using the difference data, A monitoring control unit 24 that forms information regarding the movement accuracy of the driving unit 6 is provided.

The rotary encoder 32 for drive motor and the rotary encoder 34 for wheel drive control are electrically connected to the rotary table controller 42. Thereby, feedback drive control of the drive motor 30 can be performed.
In the following, various embodiments of the movement accuracy monitoring system having the above-described device configuration will be described.

(Movement accuracy monitoring system according to the first embodiment of the present invention)
First, a movement accuracy monitoring system according to a first embodiment of the invention will be described with reference to FIG. FIG. 4 is a block diagram schematically showing a control configuration of the movement accuracy monitoring system 2 according to the first embodiment of the present invention. The arrows shown in FIGS. 4 to 6 indicate the signal flow.

  As shown in FIG. 4, the monitoring system control device 20 according to the present embodiment includes a difference detection unit 22 and a monitoring control unit 24. The difference detection unit 22 includes a shift value consideration unit 22A and a difference calculation unit 22B. Moreover, the monitoring control part 24 is comprised from the diagnostic part.

  The drive side measurement data measured by the drive shaft side sensor 10 and the driven side measurement data measured by the driven unit side sensor 12 at the timing determined in a predetermined manner are the shift value consideration unit 22A of the difference detection unit 22. Sent to. Here, the timing determined in a predetermined manner includes a timing for each fixed time interval, and also includes a timing for each (programmed) time interval based on a predetermined rule that is not fixed. In addition, the timing in some event (for example, when the drive command signal of the drive shaft 4 is transmitted) is included, and the timing of combining them is also included. Furthermore, when the drive shaft side sensor 10 and the driven part side sensor 12 are analog sensors, measurement data can be transmitted at all times.

The shift value consideration unit 22A takes into account the gear ratio in the driving force transmission unit 8 and adjusts the position or movement amount of the drive shaft 4 and the position or movement amount of the driven unit 6 so that they can be compared. Specifically, for example, the rotation angle detected by the driving unit side sensor (rotary encoder) 10 is θ10, the rotation angle detected by the driven unit side sensor (rotary encoder) 12 is θ12, and the driving force transmission unit (worm gear) ) If the reduction ratio of 8 is n,
Multiply the reduction ratio n so that the rotation angle on the driven part 6 side is the same as that on the drive shaft 4 side,
θ12aj = n × θ12
And

Θ10 and θ12aj adjusted as described above are transmitted to the difference calculation unit 22B.
The difference calculation unit 22B forms difference data Δθ between the two that can be compared. That means
Δθ = θ12aj−θ10
And the difference data Δθ is stored in the memory.

The rotation angle on the drive shaft 4 side is divided by the reduction ratio n so that it is the same as that on the driven portion 6 side,
θ10aj = θ10 / n
Calculate
Δθ = θ12−θ10aj
And the difference data Δθ can be stored in the memory.

  It is preferable that θ10 and θ12 used for this calculation are based on data measured simultaneously. However, if the two rotary encoders of the drive unit side sensor (rotary encoder) 10 and the driven unit side sensor (rotary encoder) 12 do not share the clock unit, the measurement jitter (clock jitter) for the clock. ) Will be included. This clock jitter has a greater effect when the rotational speeds of the drive shaft 4 and the driven part 6 are fast. Therefore, it is necessary to consider the clock timing according to the rotational speeds of the drive shaft 4 and the driven unit 6 so that the clock jitter is within a predetermined allowable range where reliable monitoring and diagnosis can be obtained. .

  The difference data Δθ based on one measurement data of the driving unit side sensor (rotary encoder) 10 and the driven unit side sensor (rotary encoder) 12 may have some variation. Therefore, the difference calculation unit 22B calculates the difference data average value Δθave that is the average value of the difference data Δθ calculated based on the predetermined number of times of measurement data, and the difference data average value Δθave is also stored in the memory. Thereby, monitoring and diagnosis based on data with higher reliability can be performed.

  Next, the monitoring control unit (diagnostic unit) 24 forms information related to the movement accuracy of the driven unit 6 based on the difference data Δθ or the difference data average value Δθave stored in the memory, and diagnoses the result. Send to the outside as output.

  Here, the “information regarding the movement accuracy of the driven unit” includes information indicating a change in the movement accuracy of the driven unit 6 from the initial use or when the parts are replaced (if the difference data Δθ or the difference data average value Δθave increases). It can be recognized that backlash and the like have increased), information indicating a decrease in movement accuracy of the driven unit 6, a determination result as to whether or not the movement accuracy is within an allowable range, an estimated movement distance or an estimation period until the allowable range is exceeded , Information on warning to the user, information on stopping / prohibiting driving of the drive shaft 4, information on the absolute position where the movement accuracy of the driven part 6 is particularly lowered, and the like.

  In the driving force transmission unit 8, for example, when backlash increases, a decrease in movement accuracy of the driven unit 6 becomes a problem. In the present embodiment, the movement accuracy of the driven unit 6 is based on the change in the difference data Δθ between the movement amount of the drive shaft 4 and the movement amount of the driven unit 6 in consideration of the gear ratio, or the change in the difference data average value Δθave. Therefore, it is possible to accurately monitor and diagnose a decrease in the movement accuracy of the driven unit 6. In particular, since it is based on the measured value at the timing determined in a predetermined manner, accurate monitoring and diagnosis at an appropriate timing during operation according to the application can be expected.

Therefore, the movement accuracy monitoring system 2 can accurately monitor and diagnose a decrease in movement accuracy of the driven unit 6 in actual operation in a timely manner.
In particular, by using the average value Δθ ave of the difference data for a predetermined number of times, highly reliable monitoring and diagnosis based on highly reliable measurement data can be realized.

With respect to “information about warning to the user” and “information about driving stop / driving prohibition of the drive shaft 4”, the monitoring control unit (diagnostic unit) 24 performs the following control processing.
If the difference data Δθ or the difference data average value Δθave reaches the first threshold value, a control process for warning notification is performed. In the control processing for warning notification, control for warning notification to the user by lamp display, sound, image display using a display device, etc. based on the diagnostic output transmitted from the monitoring control unit (diagnostic unit) 24 Processing is included.
These notification devices may be included in the movement accuracy monitoring system 2 or may be provided in a rotary table, a machine tool, or an NC device as described later.

If the difference data Δθ or the difference data average value Δθave reaches the second threshold value, a control process for stopping or prohibiting driving of the drive shaft 4 is performed. Based on the diagnostic output transmitted from the monitoring control unit (diagnostic unit) 24, the drive control unit of the drive motor 30 stops the drive if the drive motor 30 is being driven, and cannot be restarted. Set to. If the drive motor 30 is stopped, it is set so that it does not start even when a start signal is received.
The first threshold value and the second threshold value can be determined empirically depending on the application, can be determined by repeating the test, or can be determined based on theoretical calculations. It is possible to determine the optimum value by combining them.

  As described above, it is possible to surely prevent a malfunction from occurring by the control process for the warning or the alarm based on the proper monitoring of the decrease in the movement accuracy of the driven unit 6.

  The history of the difference data Δθ and the difference data average value Δθave calculated by the difference calculation unit 22B is preferably stored in a nonvolatile memory. Thereby, for example, when a control process for a warning or an alarm is performed and maintenance is performed, the worker takes out the history of the difference data Δθ and the difference data average value Δθave stored in the nonvolatile memory. By grasping the history of deterioration of machine elements, it is possible to carry out appropriate maintenance.

  In addition, as shown in FIG. 1 and the like, when the drive shaft side sensor 10 is attached to the end of the drive shaft 4 opposite to the drive motor 30, it is attached to the drive motor 30 depending on the resolution of the sensor. The torsion of the drive shaft 4 that affects the movement accuracy of the driven part 6 can be accurately detected by the rotary encoder 32 for the drive motor and the drive shaft side sensor 10 attached to the opposite end.

(Movement accuracy monitoring system according to the second embodiment of the present invention)
Next, a movement accuracy monitoring system according to a second embodiment of the invention will be described with reference to FIG. FIG. 5 is a block diagram schematically showing a control configuration of the movement accuracy monitoring system 2 according to the second embodiment of the present invention.

  In the movement accuracy monitoring system according to the present embodiment, the direction detection unit 22C and the direction difference unit 22D are further provided in the difference detection unit 22, as compared with the movement accuracy monitoring system according to the first embodiment. It is different.

The direction sorting unit 22C performs positive rotation when the difference between the measurement values at the time of the measurement and the previous measurement is positive in the driving unit side sensor (rotary encoder) 10 or the driven unit side sensor (rotary encoder) 12. If the difference between the measured value at the time of the measurement and the previous measurement is negative, it is determined as reverse rotation.
Based on this determination, the difference data Δθ calculated by the difference calculating unit 22B is stored as Δθp when it is determined to be forward rotation, and is stored as Δθm when it is determined to be reverse rotation. And stored in the storage location of Δθm in the memory. As the latest values of Δθp and Δθm, at the time of the next measurement, either Δθp or Δθm is rewritten to a new value.

The direction-specific difference unit 22D calculates the difference between the difference data at the timing before and after the rotation direction of the drive shaft is reversed. That is, as the difference Δ of the difference data, Δ = | Δθp−Δθm | which is the absolute value of the difference between θp and Δθm
Is calculated. The difference Δ of the difference data when the rotation direction is reversed is stored in the memory. The reason why the absolute value is used here is that the same difference data difference Δ is caused by backlash or the like regardless of the rotation direction.
However, since it is possible to discriminate whether the reversal is from positive to negative or from negative to positive, data in the direction of reversing can be individually stored in the memory. In this case, further detailed analysis is possible, such as how the amount of backlash varies depending on the direction of reverse rotation, and whether the amount of backlash varies depending on the direction of reverse rotation.

The direction-specific difference unit 22D also calculates an average value Δave of the difference data difference Δ when the rotation direction is reversed in a predetermined number of times. The average value Δave of the difference Δ is stored in the memory.
As described above, in the present embodiment, the difference detection unit 22 calculates the difference data difference Δ at the timing before and after the rotation direction of the drive shaft 4 reverses, and the average value Δave of the difference of a predetermined number of times, Stored in memory.

Next, the monitoring control unit (diagnostic unit) 24 forms information related to the movement accuracy of the driven unit 6 based on the difference Δ of the difference data stored in the memory or the change in the average value Δave of the difference, and the result Is sent to the outside as a diagnostic output. That is, in the second embodiment, instead of the “change in the difference data Δθ or the difference data average value Δθave” in the first embodiment, the difference Δ of the difference data when the rotation reverses or the average value Δave thereof is changed. Based on the “change”, information on the movement accuracy of the driven unit 6 is formed. When the difference Δ of the difference data when the rotation reverses or the change in the average value Δave thereof reaches the first threshold value or the second threshold value, the same control processing as in the first embodiment is performed accordingly. .
Since the information related to the movement accuracy formed by the monitoring control unit (diagnostic unit) 24 and the control processing associated therewith are the same as those in the first embodiment, further description is omitted.

In the driving force transmission unit 8, when the difference data Δθ in the movement in one direction is used, the movement starts from the state where the mechanical elements (for example, the worm and the worm wheel) of the driving force transmission unit 8 are in contact with each other. There is a possibility that it cannot be detected. In this embodiment, since the determination is made based on the difference Δ of the difference data Δθ at the timing before and after the rotation direction of the drive shaft is reversed, accurate monitoring and diagnosis based on accurate detection of the backlash amount is realized. it can.
Furthermore, by using the average value Δave of the difference Δ for a predetermined number of times, monitoring and diagnosis with higher reliability based on measurement data with higher reliability can be realized.

  The difference data average value Δθave, which is the average value of the difference data Δθ of the predetermined number of times as described above, the difference data difference Δ when the rotation direction is reversed, the average value Δave of the difference Δ of the predetermined number of times, etc. are collectively referred to. , “Calculated value using difference data”.

The first and second embodiments can be summarized as follows using “calculated values using difference data”.
The movement accuracy monitoring system 2
(1) a drive shaft side sensor 10 that measures the position or amount of movement of the drive shaft 4 that rotates and moves;
(2) A driven-part-side sensor 12 that measures the position or movement amount of the driven part 6 that rotates or moves on a predetermined track by the driving torque of the drive shaft 4 via the driving force transmission part 8;
(3) Based on the measured values of the drive shaft side sensor 10 and the driven portion side sensor 12 at the timing determined in a predetermined mode, the amount of movement of the drive shaft 4 and the driven state in consideration of the gear ratio in the driving force transmission portion 8 A difference detection unit 22 that forms difference data Δθ with the amount of movement of the unit 6;
(4) a monitoring control unit 24 that forms information related to the movement accuracy of the driven unit 6 based on a change in the difference data Δθ or a change in a calculation value (Δθave, Δ, Δave, etc.) using the difference data Δθ;
Is provided.

(Control processing corresponding to change in calculation value using difference data or difference data)
Next, with reference to FIG. 7, the control process corresponding to the difference data or the change of the calculated value using the difference data will be described. FIG. 7 is a graph showing the relationship between the accumulated movement length or accumulated operation period (X axis) and the difference value (Y axis) using the measurement example by the drive axis side sensor and the driven part side sensor.

The cumulative movement length of the X axis in the graph indicates the cumulative movement length of the drive shaft 4 or the driven portion 6 that has been rotationally moved in consideration of the gear ratio in the driving force transmission unit 8. If the correlation with the movement length and operation period of the drive shaft 4 or the driven part 6 is obtained, the X-axis can represent the cumulative operation period. In the graph of FIG. 7, the difference value on the Y axis of the graph indicates an average value Δave of a predetermined number of differences Δ of the difference data when the rotation direction is reversed. However, the present invention is not limited to this, and the difference value is the difference data Δθ, other calculation values using the difference data Δθ (difference data average value Δθave that is the average value of the difference data Δθ, and when the rotation direction is reversed. The difference data difference Δ, etc.) can also be used.
In the graph, changes in the difference value with respect to the actually measured accumulated movement length (accumulated operation period) are plotted as measured values 1 to 3. Further, the first threshold value and the second threshold value are indicated by lines parallel to the X axis.

As the cumulative movement length (cumulative operation period) of the drive shaft 4 or the driven part 6 increases, the difference value gradually increases due to an increase in backlash or the like. For example, in measurement example 3 (solid line), when the difference value reaches the first threshold value (see arrow E1), a control process for warning is performed. Further, when the difference value reaches the second threshold value (see arrow E2), a control process for an alarm is performed.
As is apparent from the graph, the cumulative movement length (cumulative operation period) and the difference value of each measurement value have a correlation close to linear. Therefore, the ratio R indicating the slope of each measured value in the graph is
R = increase amount of difference value corresponding to unit movement length / unit movement length, or R = increase amount of difference value corresponding to unit operation period / unit operation period working time,
Can be calculated as This ratio R is stored in the memory.

  If the current difference value and the ratio R are known, it is possible to calculate the estimated movement length or estimated operation period until the first threshold value and the second threshold value are reached. For example, in measurement example 3 (solid line), if the current difference value is a point indicated by an arrow F, since the slope R is substantially constant, the travel distance W or the operating period up to the point indicated by the arrow E1 reaching the first threshold value (Expected life) T can be calculated.

The ratio R is not limited to the above, but the reciprocal R = unit movement length / increase in the difference value corresponding to the unit movement length, or R = unit operation period / unit operation period. An increase amount of the difference value can also be used.

  As described above, the monitoring control unit 24 uses the difference data Δθ or the calculated value (Δθave, Δ, Δave, etc.) using the difference data Δθ as A, and accumulates the drive shaft 4 or the driven unit 6 in consideration of the gear ratio. When the movement amount or the cumulative operation period is B, the ratio R = A / B or B / A is calculated, and the calculation using the difference data or the difference data based on the value of A and the value of the ratio R at the latest timing The expected movement amount or the expected operation period until the value reaches the first threshold value or the second threshold value can be calculated.

  Thereby, since the movement amount or operation period until the movement accuracy of the driven part 6 exceeds a predetermined allowable range can be accurately predicted and notified to the user, it is possible to accurately detect the occurrence of a problem. Can be prevented.

  As described above, the cumulative movement length (cumulative operation period) of the drive shaft 4 or the driven unit 6 and the difference value have a linear correlation, but when the life is near, the difference value with respect to the movement length (operation period). There is a tendency for the amount of increase in Δθave to increase. That is, the ratio R indicating the slope of the graph tends to increase suddenly. For example, in measurement example 3 (solid line), it is indicated that the ratio R increases at the point indicated by the arrow G.

  Based on this, paying attention to the magnitude of the ratio R (degree of inclination in the graph), control processing for warnings and alarms can be performed according to the magnitude of the ratio R. FIG. 7 shows a third threshold value and a fourth threshold value that indicate an allowable limit regarding the ratio R (the slope of the graph). Here, the third threshold corresponds to the first threshold, and the fourth threshold corresponds to the second threshold.

  That is, the monitoring control unit 24 sets the difference data Δθ or the calculated value (Δθave, Δ, Δave, etc.) using the difference data Δθ as A, and accumulates the movement amount of the drive shaft 4 or the driven unit 6 considering the gear ratio. When the value (cumulative value of the operation period) is B, the ratio R (for example, A / B or B / A) is calculated, and when the value of the ratio R reaches the third threshold value, for warning notification When the value of the ratio R reaches the fourth threshold value, the control process for stopping the drive shaft 4 or prohibiting the drive can be performed.

  Note that “control processing for warning notification” and “control processing for stopping driving or prohibiting driving of the drive shaft 4” are the same as the case where the first threshold value and the second threshold value are reached. Further explanation is omitted.

As a result, the point at which the value of the ratio R suddenly increases, that is, the point at which the decrease in the movement accuracy of the driven unit 6 becomes significant can be accurately grasped, so the movement accuracy of the driven unit 6 can be accurately determined. The control process for warning or alarm based on the monitoring can surely prevent the occurrence of trouble.
Note that the third and fourth threshold values can also be determined empirically according to the application, can be determined by repeating the test, or can be determined based on theoretical calculations. It is also possible to determine the optimum value by combining them.

As another example, when the cumulative movement length (cumulative operation time) of the drive shaft 4 or the driven unit 6 and the difference value have a correlation that is curved in the graph, the function f similar to that curve Using,
Difference value = f (cumulative movement length),
Difference value = f (cumulative operation period)
It can also be expressed as
Using this function f, it is also possible to predict the movement length and the operation period (lifetime) until the first threshold value and the second threshold value are reached. Similarly, a control process for a warning or an alarm can be performed using the function f.

(Movement accuracy monitoring system according to the third embodiment of the present invention)
Next, a movement accuracy monitoring system according to a third embodiment of the invention will be described with reference to FIG. FIG. 6 is a block diagram schematically showing a control configuration of the movement accuracy monitoring system 2 according to the third embodiment of the present invention.

  In the movement accuracy monitoring system according to the present embodiment, compared to the movement accuracy monitoring system according to the second embodiment described above, the driven unit side measurement data from the driven unit side sensor (rotary encoder) 12 is the difference detection unit 22. The transmission value consideration unit 22 </ b> A is also transmitted to the monitoring control unit (diagnostic unit) 24. In the present embodiment, an absolute encoder capable of detecting an absolute position is used as the driven unit side sensor (rotary encoder) 12.

  In addition, since the drive shaft 4 and the driven part 6 are connected via the driving force transmission part 8, the driving part side measurement data from the driving part side sensor (rotary encoder) 10 is monitored and controlled (diagnostic part). Direct transmission to 24 can serve a similar function. In that case, an absolute encoder capable of detecting an absolute position is used as the drive unit side sensor (rotary encoder) 10.

  In the case of an absolute encoder, it is possible to identify at which position of one rotation whether the deterioration of the movement accuracy is large, that is, the backlash is large, based on the absolute angle information of one rotation. By storing the amount of backlash in the memory together with the absolute value information on the driving side and the driven side, it is possible to know the change (elapsed time) of the backlash at each specific position. For example, in a gear-type rotary table, the state of individual gears (gears) and changes in the state, such as which gears (gears) have increased backlash and the state has deteriorated as a result, are known. be able to.

  By using this fact, it is possible to distinguish the parts where the gears (gears) have deteriorated and the parts that are not so, so in the case of a machine that repeatedly performs the same processing and movement, there are many failures and backlashes. In such a case, it is possible to provide customized information in a specific use state, such as issuing warning information, alarm information, or the like depending on the situation at a specific part in use.

  Furthermore, when repairing a product that has failed, use a place where there is no problem by changing the mounting angle of the gear shaft or changing the mounting angle of the workpiece without replacing the entire device (worm gear). Thus, it is possible to resume the use easily, for example, by continuing (resuming) use.

  As described above, in the present embodiment, the drive unit side sensor (rotary encoder) 10 or the driven unit side sensor (rotary encoder) 12 is a sensor (absolute encoder) capable of detecting the absolute position, and the drive shaft 4 or The absolute position data of the driven unit 6 is stored together with the difference data Δθ and the like. Information on the absolute position of the drive unit 6 is formed. Thereby, the absolute position of the mechanical element of the driving force transmission unit 8 with a large decrease in movement accuracy can be determined.

  Therefore, in the mechanical element (for example, gear) of the driving force transmission unit 8, it is possible to distinguish between a deteriorated portion and a portion with little deterioration, and thus customized information regarding the movement accuracy of the driven portion 6 in a specific use state. Can be formed. Furthermore, the operation can be continued without exchanging the entire machine element by changing the machine element (gear) so that the part with little deterioration becomes the main operating part.

(Other examples of connection from the drive shaft side sensor and the driven unit side sensor to the monitoring system control device)
Next, another example of connection from the drive shaft side sensor and the driven unit side sensor to the monitoring system control device will be described with reference to FIG. FIG. 8 is a diagram schematically illustrating another example of the connection from the drive shaft side sensor 10 and the driven unit side sensor 12 to the monitoring system control device 20.

  In the connection example shown in FIG. 8, the drive shaft side sensor 10 and the driven unit side sensor 12 drive not only the detection signal for monitoring the movement accuracy but also the drive shaft 4 as compared with the connection example shown in FIG. 4. This is different in that a detection signal for control is also output. However, the present invention is not limited to this, and one of the drive shaft side sensor 10 and the driven unit side sensor 12 may output a detection signal for monitoring movement accuracy and a detection signal for drive control of the drive shaft 4. obtain.

  In this case, the movement accuracy monitoring and drive control can be performed individually and reliably only by providing one sensor in the drive shaft 4 or the driven part 6.

  Further, the drive shaft side sensor 10 or the driven unit side sensor 12 can transmit information on the movement accuracy of the driven unit 6 received from the monitoring control unit 24 to the control unit of the device that drives the driving shaft 4. . In other words, the sensor serves not only the transmission of measurement data but also the function of a relay base that receives and transmits signals including predetermined information.

As a result, a signal including information on movement accuracy can be transmitted to the control unit of the apparatus together with a drive control signal (position and angle signal) with a simple configuration without providing a new cable or the like. Thereby, in the apparatus which drives the drive shaft 4, required control processes, such as a warning and an alarm, can be performed.
In addition, as a control part of the apparatus which drives the drive shaft 4, the control apparatus of a rotary table, the control apparatus of a machine tool, NC apparatus etc. correspond.

(Rotary table according to one embodiment of the present invention)
Next, a rotary table according to an embodiment of the present invention will be described with reference to FIG. FIG. 9 is a diagram schematically showing a turntable 40 according to one embodiment of the present invention.

In the present embodiment, the drive shaft side sensor 10 and the driven unit side sensor 12 move as in the example of connection from the drive shaft side sensor 10 and the driven unit side sensor 12 to the monitoring system control device 20 shown in FIG. A detection signal for accuracy monitoring and a detection signal for drive control of the drive shaft 4 are output. It can also be understood that the drive motor rotary encoder 32 and the wheel drive control rotary encoder 34 output a detection signal for monitoring movement accuracy and a detection signal for drive control of the drive shaft 4.
A monitoring system control device 20 including a difference detection unit 22 and a monitoring control unit (diagnostic unit) 24 is provided in the rotary table control device 42 of the rotary table 40. In FIG. 9, a portion corresponding to the movement accuracy monitoring system 2 is surrounded by a one-dot chain line.

  However, the present invention is not limited to this, and the present invention includes the rotary table 40 including the above-described arbitrary movement accuracy monitoring system 2, and the drive shaft side sensor 10 and the driven unit side sensor 12 have the movement accuracy. A dedicated monitoring system can be provided, or a sensor for driving control of the rotary table 40 can be used. Moreover, the difference detection part 22 and the monitoring control part 24 can also be provided only for a movement accuracy monitoring system, and can also use the control apparatus 42 for rotary tables. When the difference detection unit 22 and the monitoring control unit (diagnosis unit) 24 are provided exclusively for the movement accuracy monitoring system, the rotary table control device 42 determines the drive shaft 4 based on the signal output from the movement accuracy monitoring system. A control process for stopping driving or prohibiting driving is performed.

(Machine tool according to one embodiment of the present invention)
Next, a machine tool according to one embodiment of the present invention will be described with reference to FIG. FIG. 10 is a diagram schematically showing a machine tool according to one embodiment of the present invention. In the present embodiment, the present invention can be applied not only to a rotary table used for an inclination stage or the like but also to a rotation mechanism dedicated to a machine tool.

In the present embodiment, the drive shaft side sensor 10 and the driven unit side sensor 12 move as in the example of connection from the drive shaft side sensor 10 and the driven unit side sensor 12 to the monitoring system control device 20 shown in FIG. A detection signal for accuracy monitoring and a detection signal for drive control of the drive shaft 4 are output. It can also be understood that the drive motor rotary encoder 32 and the wheel drive control rotary encoder 34 output a detection signal for monitoring movement accuracy and a detection signal for drive control of the drive shaft 4.
A monitoring system control device 20 including a difference detection unit 22 and a monitoring control unit (diagnosis unit) 24 is provided in the machine tool control device 52 of the machine tool 50. An NC device 60 for performing feedback control of the machine tool is connected to the machine tool control device 52. In FIG. 10, a portion corresponding to the movement accuracy monitoring system 2 is surrounded by a one-dot chain line.

  However, the present invention is not limited to this, and the present invention includes the machine tool 50 including the above-described arbitrary movement accuracy monitoring system 2, and the drive shaft side sensor 10 and the driven part side sensor 12 have the movement accuracy. A dedicated monitoring system can be provided, or a sensor for driving control of a machine tool or a rotary table can be used. Further, the difference detection unit 22 and the monitoring control unit 24 can be provided exclusively for the movement accuracy monitoring system, or a machine tool control device 52 of the machine tool 50 or a rotary table control device can be used. When the difference detection unit 22 and the monitoring control unit (diagnostic unit) 24 are provided exclusively for the movement accuracy monitoring system, the machine tool control device 52 or the rotary table control device is based on the signal output from the movement accuracy monitoring system. Then, control processing for stopping driving or prohibiting driving of the drive shaft 4 is performed.

(NC device according to one embodiment of the present invention)
Next, an NC apparatus according to one embodiment of the present invention will be described with reference to FIG. FIG. 11 is a diagram schematically showing an NC apparatus according to one embodiment of the present invention.

In the present embodiment, the drive shaft side sensor 10 and the driven unit side sensor 12 are used for movement accuracy monitoring, as in the connection example from the drive shaft side sensor and the driven unit side sensor to the monitoring system control device shown in FIG. And a detection signal for drive control of the drive shaft 4 are output. It can also be understood that the drive motor rotary encoder 32 and the wheel drive control rotary encoder 34 output a detection signal for monitoring movement accuracy and a detection signal for drive control of the drive shaft 4.
Moreover, the monitoring system control apparatus 20 provided with the difference detection part 22 and the monitoring control part (diagnosis part) 24 is provided in NC unit. Therefore, as described above, a signal including information relating to movement accuracy can be transmitted to the NC apparatus together with a drive control signal (position and angle signal), and thus the NC apparatus performs necessary control processing such as warning and alarm. be able to. In FIG. 11, a portion corresponding to the movement accuracy monitoring system 2 is surrounded by a one-dot chain line.

  Although the embodiments and embodiments of the present invention have been described, the disclosed contents may vary in the details of the configuration, and combinations of elements and changes in the order of the embodiments, embodiments, etc. are claimed in the present invention. It can be realized without departing from the scope and spirit of the present invention.

2 Movement accuracy monitoring system 4, 4 'drive shaft 4A worm 6, 6' driven portion 6A worm wheel 8, 8 'drive force transmitting portion 10, 10' drive shaft side sensor (rotary encoder)
12 Driven side sensor (rotary encoder)
12A Encoder head 12B Encoder scale 12 'Driven side sensor (linear encoder)
20 monitoring system control device 22 difference detection unit 22A shift value consideration unit 22B difference calculation unit 22C direction sorting unit 22D direction difference unit 24 monitoring control unit (diagnostic unit)
DESCRIPTION OF SYMBOLS 30 Drive motor 32 Rotary encoder 34 for drive motors Rotary encoder 34A for wheel drive control Encoder head 40 Rotary table 42 Rotary table controller 50 Machine tool 52 Machine tool controller 60 NC device

Claims (13)

A drive shaft side sensor for measuring the position or movement amount of the drive shaft that rotates and moves;
A driven part side sensor for measuring the position or amount of movement of the driven part that rotates or moves on a predetermined track by the driving torque of the drive shaft via the driving force transmission part;
Based on the measured values of the driving shaft side sensor and the driven unit side sensor at the timing determined in a predetermined mode, the amount of movement of the driving shaft taking into account the transmission ratio in the driving force transmission unit and the driven unit A difference detection unit that forms difference data with the movement amount;
A monitoring control unit that forms information on the movement accuracy of the driven unit based on a change in the difference data or a change in an operation value using the difference data;
A movement accuracy monitoring system characterized by comprising:   2. The movement accuracy monitoring system according to claim 1, wherein the calculated value using the difference data is an average value of the difference data a predetermined number of times. The driving force transmission part is a contact type driving force transmission device;
The calculated value using the difference data is a difference between the difference data at the timing before and after the rotation direction of the drive shaft is reversed, or an average value of the differences of a predetermined number of times. The movement accuracy monitoring system according to 1. The monitoring control unit is
When the difference data or the calculated value using the difference data reaches the first threshold value, a control process for warning notification is performed,
4. The control process for stopping driving or prohibiting driving of the drive shaft is performed when the difference data or a calculated value using the difference data reaches a second threshold value. The movement accuracy monitoring system according to item 1. The monitoring control unit is
The ratio R = A / B or B, where A is the difference data or the calculated value using the difference data, and B is the cumulative value of the amount of movement of the drive shaft or the driven part considering the gear ratio. / A is calculated,
Based on the value of A and the value of the ratio R at the most recent timing, the predicted movement amount until the calculated value using the difference data or the difference data reaches the first threshold value or the second threshold value or The movement accuracy monitoring system according to claim 4, wherein an expected period is calculated. The monitoring control unit is
When the difference data or the calculated value using the difference data is A, and the cumulative value of the amount of movement of the drive shaft or the driven part considering the gear ratio is B, the ratio R is calculated,
When the value of the ratio R reaches the third threshold value, a control process for warning notification is performed,
The movement according to any one of claims 1 to 3, wherein when the value of the ratio R reaches a fourth threshold value, a control process for stopping or prohibiting driving of the drive shaft is performed. Precision monitoring system. The driving unit side sensor or the driven unit side sensor is a sensor capable of detecting an absolute position,
The absolute position data of the drive shaft or the driven part is stored together with the difference data,
The monitoring control unit forms information on the absolute position of the drive shaft or the driven unit with a large decrease in movement accuracy as information on the movement accuracy of the drive shaft or the driven unit. The movement accuracy monitoring system according to any one of 1 to 6. The movement accuracy monitoring system according to any one of claims 1 to 7, wherein the difference data or a history of calculation values using the difference data is stored in a non-volatile memory.
Is required.   9. The drive shaft side sensor or the driven unit side sensor outputs a detection signal for monitoring movement accuracy and a detection signal for driving control of the drive shaft. The movement accuracy monitoring system described in 1.   The drive shaft side sensor or the driven unit side sensor transmits information on the movement accuracy received from the monitoring control unit to a control unit of a device that drives the drive shaft. The moving accuracy monitoring system described.   A turntable comprising the movement accuracy monitoring system according to any one of claims 1 to 10.   A machine tool comprising the movement accuracy monitoring system according to any one of claims 1 to 10.   An NC apparatus comprising the difference detection unit and the monitoring control unit according to any one of claims 1 to 10.