JP7000040B2 - Movement accuracy monitoring system, rotary table with movement accuracy monitoring function, machine tool and NC equipment - Google Patents

Description

INDUSTRIAL APPLICABILITY The present invention relates to a movement accuracy monitoring system for a driven unit that rotates or moves on a predetermined orbit by a drive torque of a drive shaft via a drive force transmission unit, and a rotary table, a machine tool, and a machine tool having a movement accuracy monitoring function. Regarding NC equipment.

As a driving force transmission unit that rotates the driven unit by the driving torque of the drive shaft, for example, a gear transmission mechanism in which gears attached to the drive shaft and the driven shaft (driven unit) are meshed with each other is widely used. In such a gear transmission mechanism, the driving force is transmitted by the contact surface of the gear, so if the contact surface of the gear is worn down after many years of use, backlash increases or slippage becomes worse, and the driven shaft side Positioning accuracy and rotation speed accuracy may deteriorate.

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 deal 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).

Patent Gazette No. 4-77259

Patent Document 1 describes that a rotary encoder is coupled to a drive shaft and a driven shaft to which gears that mesh with each other are attached, and a transmission error between the gears is detected by the phase difference between the two. However, in order to perform this test, it is necessary to remove the gear transmission mechanism from the device, and it is difficult to frequently check the deterioration of the movement accuracy of the device in operation. In addition, although transmission errors due to gear wear can be detected in this test, there are other factors that reduce the movement accuracy of the driven shaft during actual operation when the gear transmission mechanism is attached to the device. Therefore, it is not possible to accurately monitor the deterioration of movement accuracy in actual operation.

Therefore, an object of the present invention is to timely and accurately reduce the movement accuracy of the driven unit that rotates or moves on a predetermined orbit by the drive torque of the drive shaft via the drive force transmission unit in actual operation. It is an object of the present invention to provide a movement accuracy monitoring system capable of monitoring and diagnosing, and a rotary table, a machine tool and an NC device equipped with this movement accuracy monitoring function.

In order to solve the above problems and achieve the object of the present invention, the movement accuracy monitoring system according to one embodiment of the present invention is provided.
A drive shaft side sensor that measures the position or amount of movement of the drive shaft that rotates and moves,
A sensor on the driven unit side that measures the position or amount of movement of the driven unit that rotates or moves on a predetermined orbit by the driving torque of the drive shaft via the driving force transmission unit.
Based on the measured values of the drive shaft side sensor and the driven unit side sensor at the timing determined in the predetermined embodiment, the movement amount of the drive shaft and the driven unit in consideration of the gear ratio in the driving force transmission unit. A difference detector that forms difference data with the movement amount,
A monitoring control unit that forms information regarding the movement accuracy of the driven unit based on the change in the difference data or the change in the calculated value using the difference data.
To prepare for.

The rotary table according to one embodiment of the present invention includes the above-mentioned movement accuracy monitoring system.

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

The NC device according to one embodiment of the present invention includes the above-mentioned difference detection unit and monitoring control unit.

According to the movement accuracy monitoring system, the rotary table, the machine tool, and the NC device of the above-described embodiment, the driven unit that rotates or moves in a predetermined orbit by the drive torque of the drive shaft via the drive 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 arrangement example of the drive shaft side sensor and the driven part side sensor in the case where the driven part is rotationally moved by the drive torque of the drive shaft through the drive force transmission part. An example of arrangement of the drive shaft side sensor and the driven unit side sensor in the case where the driven unit moves in a predetermined orbit (here, movement in a linear direction) by the drive torque of the drive shaft via the drive force transmission unit is shown. It is a diagram schematically. It is a figure which shows an example of the connection from the drive shaft side sensor and the driven part side sensor to a monitoring system control device schematically. It is a block diagram which shows typically the control structure of the movement accuracy monitoring system which concerns on 1st Embodiment of this invention. It is a block diagram which shows typically the control structure of the movement accuracy 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 accuracy monitoring system which concerns on 3rd Embodiment of this invention. It is a graph which showed the relationship between the cumulative movement length or the cumulative operation period (X-axis), and the difference value (Y-axis) using the measurement example by the drive shaft side sensor and the driven part side sensor. It is a figure which shows the other example of the connection from the drive shaft side sensor and the driven part side sensor to a monitoring system control device schematically. It is a figure which shows typically the rotary table which concerns on one Embodiment of this invention. It is a figure which shows typically the machine tool which concerns on one Embodiment of this invention. It is a figure which shows typically the NC apparatus which concerns on one Embodiment of this invention.

Hereinafter, various embodiments and examples for carrying out the present invention will be described with reference to the drawings. In each drawing, the corresponding members having the same function are designated by the same reference numerals. Although the embodiments (Examples) are shown separately for convenience in consideration of the explanation of the main points or the ease of understanding, partial replacement or combination of the configurations shown in different embodiments (Examples) is possible. In the second and subsequent embodiments (other examples), the description of matters common to the first embodiment (one example) will be omitted, and only the differences will be described. In particular, the same action and effect due to the same configuration will not be mentioned sequentially for each embodiment (Example). Further, 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 rotates or moves on a predetermined orbit by the drive torque of the drive shaft via a drive shaft side sensor that measures the position or the amount of movement of the drive shaft that rotates and moves. A driven unit side sensor for measuring the position or movement amount of the driven unit is provided. In addition, "via the driving force transmission unit" means that the driving force and the driving torque are transmitted by the physical contact of the mechanical element 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 unit rotates and moves>
First, with reference to FIG. 1, an arrangement example in which the driven portion rotates and moves will be described. FIG. 1 schematically shows an arrangement example of the drive shaft side sensor 10 and the driven unit side sensor 12 when the driven unit 6 is rotationally moved by the drive torque of the drive shaft 4 via the drive force transmission unit 8. It is a figure.

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

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

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

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

Further, a drive shaft side sensor 10 of the movement accuracy monitoring system 2 including a rotary encoder is attached to an end portion of the drive shaft 4 on the opposite side of the drive motor 30. The drive shaft side sensor (rotary encoder) 10 can accurately measure the rotation position and the amount of rotation of the drive shaft 4 of the drive motor 30.
The driven unit 6 has the above-mentioned encoder scale 12B, and further, 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 in the circumferential direction from the encoder head 34A). Has been done. The encoder head 12A and the encoder scale (rotary encoder) 12B constitute a driven unit side sensor 12 of the movement accuracy monitoring system 2 including a rotary encoder. The driven unit side sensor (rotary encoder) 12 can accurately measure the rotation position and the amount of rotation of the driven unit 6.

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

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

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

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

In the example shown in FIG. 2, a drive shaft side sensor 10'made of a rotary encoder is attached to a drive shaft 4'rotated by the drive torque of the drive motor 30'. It can be shared with the rotary encoder for drive control of the drive motor 30', or it can be provided separately.
Further, a driven unit side sensor 12'made of a linear encoder is provided along the moving direction of the driven unit 6'. It can be shared with the linear encoder for drive control of the drive motor 30', or it can be provided separately.

Even when the driven unit 6'moves on a predetermined orbit as described above, the movement according to any embodiment of the present invention described below will be described in the same manner as when the driven unit 6 rotates and moves. The accuracy monitoring system 2 can be applied.

In the examples of FIGS. 1 and 2, a drive motor (electric motor) for rotating the drive shaft 4 is provided, but the present invention is not limited to this, and any rotary drive source such as a hydraulic motor, an air motor, and a prime mover is provided. 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, but the present invention is not limited to this, and any other gear such as spur teeth and bevel teeth may be used. It can be used, or a planetary gear can 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, but the rotary encoder is not limited to this, and any other digital rotation that transmits a digital signal at a predetermined interval is not limited to this. Sensors can also be used. Further, an analog sensor such as a potentiometer that continuously outputs measured values can also be used.

(An example of connection from the drive shaft side sensor and the driven unit side sensor to the monitoring system control device)
Next, with reference to FIG. 3, the electrical connection from the drive shaft side sensor and the driven unit side sensor to the monitoring system control device will be described by taking the case shown in FIG. 1 as an example. FIG. 3 is a diagram schematically showing 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, the driven shaft 4 is driven to rotate and move by the drive torque of the drive shaft 4 via the drive shaft side sensor 10 that measures the position or the amount of movement of the drive shaft 4 that rotates and moves, and the drive force transmission unit 8. The driven unit side sensor 12 that measures the position or the amount of movement of the unit 6 is electrically connected to the monitoring system control device 20.
In the monitoring system control device 20, the speed change in the driving force transmission unit 8 is 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 the predetermined mode. Based on the difference detection unit 22 that forms the 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 in the difference data or the change in the calculated value using the difference data. A monitoring control unit 24 that forms information regarding the movement accuracy of the drive unit 6 is provided.

Further, the rotary encoder 32 for the drive motor and the rotary encoder 34 for wheel drive control are electrically connected to the rotary table control device 42. This makes it possible to perform feedback drive control of the drive motor 30.
Hereinafter, various embodiments of the mobile accuracy monitoring system having the above-mentioned equipment configuration will be described.

(Movement accuracy monitoring system according to the first embodiment of the present invention)
First, the movement accuracy monitoring system according to the first embodiment of the invention will be described with reference to FIG. 4. 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. Further, the monitoring control unit 24 is composed of a diagnostic unit.

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 are the shift value consideration unit 22A of the difference detection unit 22 at the timing determined in the predetermined embodiment. Will be sent to. Here, the timing defined in the predetermined embodiment includes the timing at regular time intervals, and also includes the non-constant timing at each time interval (programmed) based on a predetermined rule. However, the timing in some event (for example, when the drive command signal of the drive shaft 4 is transmitted) is also included, and the timing in which they are combined is also included. Further, when the drive shaft side sensor 10 and the driven unit side sensor 12 are analog sensors, it is possible to constantly transmit measurement data.

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

The θ10 and θ12aj adjusted as described above are transmitted to the difference calculation unit 22B.
The difference calculation unit 22B forms the difference data Δθ between the two that can be compared. in short,
Δθ = θ12aj－θ10
Is calculated, and this 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 as to be the same as that on the driven portion 6 side.
θ10aj = θ10 / n
Calculate and
Δθ = θ12-θ10aj
Can be calculated and the difference data Δθ can be stored in the memory.

It is preferable that θ10 and θ12 used in this calculation are based on the data measured at the same time. However, if the two rotary encoders, 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 is taken. ) Will be included. This clock jitter has a greater effect when the rotation speeds of the drive shaft 4 and the driven portion 6 are high. Therefore, it is necessary to consider the clock timing according to the rotation speed of the drive shaft 4 and the driven unit 6 so that the clock jitter falls within a predetermined allowable range in which reliable monitoring and diagnosis can be obtained. ..

The difference data Δθ based on the one-time measurement data of the drive unit side sensor (rotary encoder) 10 and the driven unit side sensor (rotary encoder) 12 may have some variations. Therefore, the difference calculation unit 22B calculates the difference data average value Δθave, which is the average value of the difference data Δθ calculated based on the measurement data of a predetermined number of times, and the difference data average value Δθave is also stored in the memory. As a result, monitoring and diagnosis can be performed based on more reliable data.

Next, the monitoring control unit (diagnosis unit) 24 forms information on the movement accuracy of the driven unit 6 based on the change in 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 at the time of component replacement (if the difference data Δθ or the difference data average value Δθave becomes large). (It can be recognized that backlash etc. have increased), information indicating a decrease in the movement accuracy of the driven unit 6, a judgment result of whether or not the movement accuracy is within the allowable range, an estimated travel distance or an estimated period until the allowable range is exceeded. , Information on warning to the user, information on drive stop / drive prohibition of the drive shaft 4, information on the absolute position where the movement accuracy of the driven unit 6 is particularly lowered, and the like are included.

In the driving force transmission unit 8, for example, when the backlash increases, a decrease in the moving 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. Since information about the driven unit 6 is formed, 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 values at the timing determined in the predetermined mode, accurate monitoring and diagnosis at the appropriate timing during operation according to the application can be expected.

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

Regarding "information on warning to the user" and "information on drive stop / drive prohibition of the drive shaft 4," the monitoring control unit (diagnosis 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 process for warning notification, control to notify the user of a warning by lamp display, voice, image display using a display device, etc. based on the diagnostic output transmitted from the monitoring control unit (diagnosis unit) 24. Processing is included.
The device for notifying these 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 the drive of the drive shaft 4 is performed. Based on the diagnostic output transmitted from the monitoring control unit (diagnosis unit) 24, the drive control unit of the drive motor 30 stops driving if the drive motor 30 is driving, and cannot be restarted. Set to. If the drive motor 30 is stopped, it is set to a state in which it does not start even if it receives a start signal.
Regarding the first threshold value and the second threshold value, the optimum value can be empirically determined depending on the application, the optimum value can be determined by repeating the test, or the optimum value can be determined based on theoretical calculation. It can be done, or it can be combined to determine the optimum value.

As described above, the control process for the warning or the alarm based on the accurate monitoring of the deterioration of the movement accuracy of the driven unit 6 can surely prevent the trouble from occurring.

It is preferable that the history of the difference data Δθ and the difference data average value Δθave calculated by the difference calculation unit 22B is stored in the non-volatile memory. As a result, 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 non-volatile memory. , It is possible to grasp the history of deterioration of machine elements and perform appropriate maintenance.

Further, 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 on the opposite side to the drive motor 30, it is attached to the drive motor 30 depending on the resolution of the sensor. The rotary encoder 32 for the drive motor and the drive shaft side sensor 10 attached to the opposite end can accurately detect the twist of the drive shaft 4 that affects the movement accuracy of the driven unit 6.

(Movement accuracy monitoring system according to the second embodiment of the present invention)
Next, the movement accuracy monitoring system according to the 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 difference detection unit 22 is further provided with the direction sorting unit 22C and the direction-specific difference unit 22D, as compared with the movement accuracy monitoring system according to the first embodiment. Is different.

The direction sorting unit 22C rotates forward when the difference between the measured values at the time of the measurement and the measurement value at the time of the previous measurement is positive in the drive 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 measurement value at the time of the previous measurement is negative, it is judged to be reverse rotation.
Based on this judgment, the difference data Δθ calculated by the difference calculation unit 22B is stored as Δθp when it is determined to be forward rotation, stored in the storage location of Δθp in the memory, and as Δθm when it is determined to be reverse rotation. , Stored in the storage location of Δθm in the memory. As the latest values of Δθp and Δθm, either Δθp or Δθm is rewritten to a new value at the next measurement.

The direction-specific difference unit 22D calculates the difference in 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 a similar difference Δ of the difference data occurs due to backlash or the like regardless of the rotation direction.
However, since it is possible to distinguish between positive-to-negative reversal and negative-to-positive reversal, data in the direction of reversal can be individually stored in the memory. In this case, more detailed analysis is possible, such as what the amount of backlash will be depending on the direction of reversal, and whether the amount of backlash will be different depending on the direction of reversal.

The direction-specific difference unit 22D also calculates the average value Δave of the difference Δ of the difference data when the rotation direction is reversed in a predetermined number of times. The average value Δave of this difference Δ is stored in the memory.
As described above, in the present embodiment, the difference detection unit 22 calculates the difference Δ of the difference data 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 (diagnosis unit) 24 forms information on the movement accuracy of the driven unit 6 based on the change of the difference Δ or the average value Δave of the difference data stored in the memory, and the result is Is sent to the outside as 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 data difference Δ when the rotation is reversed or the average value Δave thereof" is used. Based on the "change", information regarding the movement accuracy of the driven unit 6 is formed. When the difference Δ of the difference data or the change of the average value Δave when the rotation is reversed reaches the first threshold value or the second threshold value, the same control process as in the first embodiment is performed accordingly. ..
Since the information regarding the movement accuracy formed by the monitoring control unit (diagnosis unit) 24 and the control processing associated therewith are the same as those in the first embodiment described above, further description thereof will be omitted.

When the difference data Δθ in the one-way movement is used in the driving force transmission unit 8, the movement is started 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, and the backlash is caused. It may not be detected. In the present 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 the accurate detection of the backlash amount are realized. can.
Further, by using the average value Δave of the difference Δ of a predetermined number of times, more reliable monitoring and diagnosis can be realized based on the more reliable measurement data.

As described above, the difference data average value Δθave, which is the average value of the difference data Δθ of the predetermined number of times, the difference Δ of the difference data when the rotation direction is reversed, and the average value Δave of the difference Δ of the predetermined number of times are collectively used. , Can also be referred to as "calculated value using difference data".

The first and second embodiments can be summarized as follows by using the "calculated value using the difference data".
The movement accuracy monitoring system 2 is
(1) A drive shaft side sensor 10 that measures the position or amount of movement of the drive shaft 4 that rotates and moves, and
(2) A driven unit side sensor 12 that measures the position or amount of movement of the driven unit 6 that rotates or moves on a predetermined orbit by the driving torque of the drive shaft 4 via the driving force transmission unit 8.
(3) Based on the measured values of the drive shaft side sensor 10 and the driven unit side sensor 12 at the timing determined in the predetermined embodiment, the movement amount of the drive shaft 4 and the driven unit in consideration of the gear ratio in the drive force transmission unit 8. The difference detection unit 22 that forms the difference data Δθ with the movement amount of the unit 6 and
(4) A monitoring control unit 24 that forms information on the movement accuracy of the driven unit 6 based on a change in the difference data Δθ or a change in a calculated value (Δθave, Δ, Δave, etc.) using the difference data Δθ.
To prepare for.

(Control processing corresponding to changes in calculated values 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 cumulative movement length or the cumulative operating period (X-axis) and the difference value (Y-axis) using measurement examples by the drive shaft side sensor and the driven unit 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 unit 6 in consideration of the gear ratio in the drive force transmission unit 8. If a correlation is obtained for the moving length of the drive shaft 4 or the driven unit 6 and the operating period, the X-axis can be made to represent the cumulative operating period. In the graph of FIG. 7, the difference value on the Y-axis of the graph indicates the average value Δave of the difference Δ of the difference data when the rotation direction is reversed for a predetermined number of times. However, the present invention is not limited to this, and the difference value is the difference data Δθ, other calculated values using the difference data Δθ (difference data average value Δθave, which is the average value of the difference data Δθ, and when the rotation direction is reversed). It is also possible to use the difference Δ of the difference data of.
In the graph, changes in the difference value with respect to the actually measured cumulative movement length (cumulative operating period) are plotted as the measured values 1 to 3. Further, the first threshold value and the second threshold value are shown by lines parallel to the X-axis.

As the cumulative movement length (cumulative operating period) of the drive shaft 4 or the driven unit 6 increases, the difference value gradually increases due to an increase in backlash and the like. For example, in measurement example 3 (solid line), when the difference value reaches the first threshold value (see arrow E1), the control process for warning is executed. Further, when the value of the difference value reaches the second threshold value (see arrow E2), the control process for the alarm is executed.
As is clear from the graph, the cumulative movement length (cumulative operating period) and the difference value of each measured value have a correlation close to linear. Therefore, the ratio R indicating the slope of each measured value in the graph is
R = increase in difference value corresponding to unit movement length / unit movement length, or R = increase in 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, the estimated movement length or the estimated operating period until the first threshold value and the second threshold value are reached can be calculated. For example, in measurement example 3 (solid line), assuming that the current difference value is the point indicated by the arrow F, since the slope R is almost constant, the moving distance W or the operating period to the point indicated by the arrow E1 reaching the first threshold value is reached. (Expected life) T can be calculated.

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

As described above, the monitoring control unit 24 sets the calculated value (Δθave, Δ, Δave, etc.) using the difference data Δθ or 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 cumulative operating 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. It is possible to calculate the expected movement amount or the expected operating period until the value reaches the first threshold value or the second threshold value.

As a result, it is possible to accurately predict the amount of movement or the operating period until the movement accuracy of the driven unit 6 exceeds a predetermined allowable range, and notify the user, so that it is possible to accurately determine that a problem will occur. Can be prevented.

As described above, the cumulative movement length (cumulative operating period) of the drive shaft 4 or the driven unit 6 and the difference value have a near-linear correlation, but when the life is approaching, the difference value with respect to the movement length (operation period). The amount of increase in Δθave tends to be large. 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 shown that the ratio R increases at the point indicated by the arrow G.

Based on this, it is also possible to pay attention to the magnitude of the ratio R (the degree of inclination in the graph) and perform control processing for warnings and alarms according to the magnitude of the ratio R. FIG. 7 shows a third threshold value and a fourth threshold value indicating an allowable limit for the ratio R (slope of the graph). Here, the third threshold value corresponds to the first threshold value, and the fourth threshold value corresponds to the second threshold value.

That is, the monitoring control unit 24 sets the calculated value (Δθave, Δ, Δave, etc.) using the difference data Δθ or the difference data Δθ as A, and accumulates the movement amount of the drive shaft 4 or the driven unit 6 in consideration of the gear ratio. When the value (cumulative value of the operating 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 or prohibiting the drive of the drive shaft 4 can be performed.

The "control process for warning notification" and "control process for driving stop or prohibition of drive shaft 4" are the same as when the first threshold value and the second threshold value are reached. Further description will be omitted.

As a result, it is possible to accurately grasp the point where the value of the ratio R suddenly increases, that is, the point where the movement accuracy of the driven unit 6 is significantly reduced, so that the movement accuracy of the driven unit 6 is accurate. Control processing for warnings or alarms based on monitoring can reliably prevent problems from occurring.
Regarding the third threshold value and the fourth threshold value, the optimum value can be empirically determined according to the application, the optimum value can be determined by repeating the test, and the optimum value is determined based on the theoretical calculation. It can be done, or they can be combined to determine the optimum value.

As another example, when the cumulative movement length (cumulative operating time) of the drive shaft 4 or the driven portion 6 and the difference value have a correlation such that the graph has a curved shape, a function f similar to the curve. Using,
Difference value = f (cumulative movement length),
Difference value = f (cumulative operating period)
It can also be expressed as.
Using this function f, it is also possible to predict the movement length and the operating period (life) until the first threshold value and the second threshold value are reached. Similarly, the function f can be used to perform control processing for warnings or alarms.

(Movement accuracy monitoring system according to the third embodiment of the present invention)
Next, the movement accuracy monitoring system according to the 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, as compared with the movement accuracy monitoring system according to the second embodiment, the difference detection unit 22 receives the measured data from the driven unit side sensor (rotary encoder) 12 to the driven unit side. It is different in that it is not only transmitted to the shift value consideration unit 22A but also to the monitoring control unit (diagnosis unit) 24. Further, in the present embodiment, an absolute encoder capable of detecting an absolute position is used as the driven unit side sensor (rotary encoder) 12.

Since the drive shaft 4 and the driven unit 6 are connected via the drive force transmission unit 8, the measurement data on the drive unit side is transmitted from the drive unit side sensor (rotary encoder) 10 to the monitoring control unit (diagnosis unit). Making it transmitted directly to 24 can also perform 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 specify at which position in one rotation the movement accuracy is greatly reduced, 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 of the driven side and the driven side, it is possible to know the change (progress) of the backlash at each specific position. For example, in a gear-type rotary table, it is possible to know the state of each gear (gear) and the change in the state, such as which gear (gear) backlash amount increases and the state deteriorates as a result. be able to.

By using this, it is possible to distinguish between the deteriorated part and the non-deteriorated part of the gear, so it is used in the case of a machine that repeatedly performs the same processing and movement, or if it breaks down or backlashes frequently. It can be customized information in a specific usage state, such as issuing warning information, alarm information, etc. depending on the situation in a specific place where the user is using.

Furthermore, even when repairing a malfunction, use a place where there is no problem by changing the mounting angle of the gear with respect to the shaft or changing the mounting angle of the work piece without replacing the entire device (worm gear). It is possible to easily return to use, such as being able to continue (restart) 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 type encoder) capable of detecting an absolute position, and the drive shaft 4 or The data of the absolute position of the driven unit 6 is stored together with the difference data Δθ and the like, and the monitoring control unit 24 uses the drive shaft 4 or the driven unit 24 as information on the movement accuracy of the drive shaft 4 or the driven unit 6 with a large decrease in the movement accuracy. It forms information on the absolute position of the drive unit 6. As a result, the absolute position of the mechanical element of the driving force transmission unit 8 whose movement accuracy is greatly reduced can also be determined.

Therefore, in the mechanical element (for example, a gear) of the driving force transmission unit 8, it is possible to discriminate between a deteriorated portion and a less deteriorated portion, so that customized information regarding the movement accuracy of the driven portion 6 in a specific usage state can be determined. Can be formed. Further, by changing the part where the deterioration of the machine element (gear) is small to be the main operating part, the operation can be continued without replacing the entire machine element.

(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 the 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 showing 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. It differs in that it also outputs a detection signal for control. 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 drive shaft 4 or the driven unit 6 is provided with only one sensor, and the movement accuracy monitoring and the drive control can be individually and reliably performed.

Further, the drive shaft side sensor 10 or the driven unit side sensor 12 can transmit the information regarding 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 drive shaft 4. .. That is, the sensor not only transmits measurement data, but also functions as a relay base for receiving and transmitting signals including predetermined information.

As a result, a signal including information on movement accuracy can be transmitted to the control unit of the device together with a drive control signal (position or angle signal) with a simple configuration without providing a new cable or the like. As a result, in the device that drives the drive shaft 4, necessary control processes such as warnings and alarms can be performed.
The control unit of the device that drives the drive shaft 4 includes a rotary table control device, a machine tool control device, an NC device, and the like.

(Rotary table according to one embodiment of the present invention)
Next, the rotary table according to one embodiment of the present invention will be described with reference to FIG. 9. FIG. 9 is a diagram schematically showing a rotary table 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 connection example from the drive shaft side sensor 10 and the driven unit side sensor 12 shown in FIG. 8 to the monitoring system control device 20. A detection signal for accuracy monitoring and a detection signal for drive control of the drive shaft 4 are output. It can also be considered that the rotary encoder 32 for the drive motor and the rotary encoder 34 for the wheel drive control output the detection signal for monitoring the movement accuracy and the detection signal for the drive control of the drive shaft 4.
Further, a monitoring system control device 20 including a difference detection unit 22 and a monitoring control unit (diagnosis unit) 24 is provided in the rotary table control device 42 of the rotary table 40. In FIG. 9, the portion corresponding to the movement accuracy monitoring system 2 is surrounded by a alternate long and short dash line.

However, the present invention is not limited to this, and the present invention includes a rotary table 40 provided with the above-mentioned arbitrary movement accuracy monitoring system 2, and the drive shaft side sensor 10 and the driven unit side sensor 12 have movement accuracy. It can be provided exclusively for the monitoring system, or a sensor for driving control of the rotary table 40 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 the rotary table control device 42 can be used. When the difference detection unit 22 and the monitoring control unit (diagnosis unit) 24 are provided exclusively for the movement accuracy monitoring system, the drive shaft 4 of the rotary table control device 42 is based on the signal output from the movement accuracy monitoring system. Performs control processing to stop driving or prohibit driving.

(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 this embodiment, it can be applied not only to a rotary table used for an inclined stage or the like, but also to a rotary 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 connection example from the drive shaft side sensor 10 and the driven unit side sensor 12 shown in FIG. 8 to the monitoring system control device 20. A detection signal for accuracy monitoring and a detection signal for drive control of the drive shaft 4 are output. It can also be considered that the rotary encoder 32 for the drive motor and the rotary encoder 34 for wheel drive control output the detection signal for monitoring the movement accuracy and the detection signal for the drive control of the drive shaft 4.
Further, 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. The NC device 60 for performing feedback control of the machine tool is connected to the machine tool control device 52. In FIG. 10, the portion corresponding to the movement accuracy monitoring system 2 is surrounded by a alternate long and short dash line.

However, the present invention is not limited to this, and the present invention includes the machine tool 50 provided with the above-mentioned arbitrary movement accuracy monitoring system 2, and the drive shaft side sensor 10 and the driven unit side sensor 12 have movement accuracy. It can be provided exclusively for the monitoring system, 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 the machine tool control device 52 of the machine tool 50 or the control device of the rotary table can be used. When the difference detection unit 22 and the monitoring control unit (diagnosis 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. In, the control process for stopping the drive of the drive shaft 4 or prohibiting the drive is performed.

(NC device according to one embodiment of the present invention)
Next, the NC device according to one embodiment of the present invention will be described with reference to FIG. FIG. 11 is a diagram schematically showing an NC device 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 for moving accuracy monitoring, as in the connection example from the drive shaft side sensor and the driven unit side sensor shown in FIG. 8 to the monitoring system control device. And the detection signal for the drive control of the drive shaft 4 are output. It can also be considered that the rotary encoder 32 for the drive motor and the rotary encoder 34 for wheel drive control output the detection signal for monitoring the movement accuracy and the detection signal for the drive control of the drive shaft 4.
Further, a monitoring system control device 20 including a difference detection unit 22 and a monitoring control unit (diagnosis unit) 24 is provided in the NC device. Therefore, as described above, a signal including information on movement accuracy can be transmitted to the NC device together with a drive control signal (position or angle signal), so that the NC device performs necessary control processing such as warnings and alarms. be able to. In FIG. 11, the portion corresponding to the movement accuracy monitoring system 2 is surrounded by a alternate long and short dash line.

Although the embodiments and embodiments of the present invention have been described, the disclosed contents may be changed in the details of the configuration, and the present invention is requested to change the combinations and orders of the elements in the embodiments and embodiments. It can be realized without deviating from the scope and idea of.

2 Movement accuracy monitoring system 4, 4'Drive shaft 4A Warm 6, 6'Driven unit 6A Warm wheel 8, 8'Drive force transmission unit 10, 10'Drive shaft side sensor (rotary encoder)
12 Driven unit side sensor (rotary encoder)
12A Encoder head 12B Encoder scale 12'Driven unit side sensor (linear encoder)
20 Monitoring system control device 22 Difference detection unit 22A Shift value consideration unit 22B Difference calculation unit 22C Direction classification unit 22D Directional difference unit 24 Monitoring control unit (diagnosis unit)
30 Drive motor 32 Rotary encoder for drive motor 34 Rotary encoder for wheel drive control 34A Encoder head 40 Rotary table 42 Rotary table control device 50 Machine tool 52 Machine tool control device 60 NC device

Claims (13)

It is provided with a worm provided on the drive shaft and a worm wheel attached to the driven portion, and measurement data from at least a drive motor sensor attached to the rotary shaft of the drive motor attached to one end of the drive shaft and the cover. Based on the measurement data from the sensor attached to the drive unit, the movement accuracy of the worm gear type drive force transmission mechanism that controls the feedback of the drive motor is monitored, and the drive motor sensor is attached to the drive shaft. A system that is attached to the drive motor side that drives the drive shaft and measures the position or the amount of movement of the drive shaft that rotates and moves.
Based on the measured value of the drive shaft side sensor mounted on the opposite side of the drive shaft with respect to the drive shaft, the drive torque of the drive shaft is used via the drive force transmission mechanism between the worm and the worm wheel. A driven unit side sensor that measures the position or movement amount of the driven unit that rotates under the influence of the driving force transmission mechanism, and
The movement amount of the drive shaft in consideration of the reduction ratio in the drive force transmission mechanism based on the measured values of the drive motor sensor, the drive shaft side sensor and the driven unit side sensor at the timing determined in the predetermined embodiment. And the difference detection unit that forms the difference data between the driven unit and the movement amount of the driven unit,
A monitoring control unit that forms information regarding the movement accuracy of the driven unit based on the change in the difference data or the change in the calculated value using the difference data.
A movement accuracy monitoring system characterized by being equipped with. 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 transmitting unit is a contact type driving force transmitting device.
The claim is characterized in that the calculated value using the difference data is the difference of the difference data at the timing before and after the rotation direction of the drive shaft is reversed, or the average value of the difference a predetermined number of times. The movement accuracy monitoring system according to 1. The monitoring control unit
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.
Any of claims 1 to 3, wherein when the difference data or the calculated value using the difference data reaches the second threshold value, the control process for driving stop or driving prohibition of the drive shaft is performed. The movement accuracy monitoring system described in item 1. The monitoring control unit
When the difference data or the calculated value using the difference data is A and the cumulative value of the movement amount of the drive shaft or the driven portion in consideration of the gear ratio is B, the ratio R = A / B or B. Calculate / A,
Based on the value of A and the value of the ratio R at the latest timing, the expected movement amount or the expected movement amount until the difference data or the calculated value using the difference data reaches the first threshold value or the second threshold value. The movement accuracy monitoring system according to claim 4, wherein the expected period is calculated. The monitoring control unit
When the difference data or the calculated value using the difference data is A, and the cumulative value of the movement amount of the drive shaft or the driven portion in consideration of 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 the fourth threshold value, a control process for stopping or prohibiting the drive of the drive shaft is performed. Precision monitoring system. The drive shaft side sensor or the driven unit side sensor is a sensor capable of detecting an absolute position.
The data of the absolute position of the drive shaft or the driven portion is stored together with the difference data.
The present invention is characterized in that the monitoring control unit forms information on the absolute position of the drive shaft or the driven unit, which has 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 the history of the calculated value using the difference data is stored in the non-volatile memory. One of claims 1 to 8, wherein the drive shaft side sensor or the driven unit side sensor outputs a detection signal for monitoring movement accuracy and a detection signal for drive control of the drive shaft. The movement accuracy monitoring system described in. The ninth aspect of the present invention is characterized in that the drive shaft side sensor or the driven unit side sensor transmits information regarding the movement accuracy received from the monitoring control unit to the control unit of the device that drives the drive shaft. The described movement accuracy monitoring system. A rotary table 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 device including the difference detection unit and the monitoring control unit according to any one of claims 1 to 10.

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