JPH0362103A - Coordinate detecting device for nc servomotor driving system - Google Patents

Abstract

PURPOSE:To facilitate the continuation of interrupted operation after the return of the NC servomotor driving system to its origin by enabling the NC servomotor driving system to return to the origin according to the mount position of a sensor. CONSTITUTION:When a program ends, a needle 14 returns to the work origin temporarily, but is stops temporarily at the installation place of the sensor 16 and a controller moves down a piston 19 under sequence control. A switch needle is pressed down by the piston 19 and a movable contact contacts a fixed contact again; and a core is demagnetized while a sensor house 20 is attracted to the piston 19. The piston 19 is elevated again and an operation element returns to a stand-by position while attracting the sensor house 20.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a coordinate detection device for an NC servo motor drive system that detects coordinates using a rotary encoder connected to a drive motor, and particularly relates to a coordinate detection device for an NC servo motor drive system. The present invention relates to a coordinate detection device for an NC servo motor drive system that is capable of continuing the work that was performed before the power was cut off after the power is restored when the power is cut off.

[Conventional technology]

FIG. 5 is a schematic configuration diagram of a conventional coordinate detection device using an NC servo motor drive system, and reference numeral 11 in the figure indicates drive motors for the X-axis, Y-axis, etc. The angular displacement of the motor 11 is determined by a rotary encoder 12 as a coordinate detector connected to the motor 11.
Detected in 13 is a ball screw that rotates in accordance with the rotation of the motor 11.

■4 is the ball screw 13 according to the rotation of the ball screw 13.
is a movable element that moves in the left-right direction (direction of arrow A9) in the figure, and the displacement of this movable element 14 is always determined by the rotary encoder 1.
This results in an angular displacement of 2. Although 15 does not actually exist, it is assumed for convenience of explanation that it is an assumed scale (virtual scale) that allows the displacement of the movable element 14 to be directly read. A sensor 16 detects that the movable element 14 is nearby, and is installed and fixed at a predetermined position along the movement locus of the movable element 14.

17 is a counter circuit, 18 is a battery backup
It's memory.

In such a conventional device, how to determine the machine origin (here, the unique origin determined by the machine, and refers to the absolute origin that does not change due to data changes, etc.) and the method for searching the machine origin are shown in Figure 6 and This will be described below with reference to FIG.

FIG. 6 is an enlarged sectional view of the rotary encoder 12 in FIG. 5, and FIG. 7 is a diagram showing the positions of the machine origin and the like on the virtual scale 15 in FIG. 5. In both of these figures, the triangular mark (Δ) 201.301 is the origin mark, and the rotary encoder 12. Machine origin on virtual scale 15 (
position). In FIG. 6, the Z phase detection window (two points) 202 of the rotary encoder 12 is the starting point of the drive system, and the origin mark 201 represents the angular displacement between the two points 202. . Furthermore, when the movable element 14 moves rightward in the figure on the virtual scale 15, the origin mark 201 on the rotary encoder 12 rotates counterclockwise in the figure.

In such a relationship, first, an arbitrary point is determined as the machine origin.Normally, the position of the origin mark 2QL, 301 is determined as the machine origin. Here, the angular displacement when the origin mark 201 in FIG. 6 reaches the two points 202 by turning counterclockwise is assumed to be 203. Similarly, the two points in FIG. 7 are 302, the origin mark 301 and the two points 302.
The amount of displacement between them is assumed to be 303.

These angular displacements 203 or displacement amounts 303 are converted into pulses by the pulse encoder 12 in FIG. 5, counted by the counter circuit 16, and stored in the battery backup memory 17. As a result, the value of the angular displacement 203 or the displacement amount 303 remains even if the power is cut off due to a power outage or the like while the drive system is in operation.

In FIG. 6, the angular displacement from the two points 202 until the two points are detected again after one rotation is 204, and this angular displacement 20
The amount of displacement on the virtual scale 15 in FIG. 7 corresponding to 4 is defined as 304. The two points 202 detected again after one rotation in FIG. 6 become point Z' 305 in FIG. Then, the sensor 16 is installed and fixed between two points 302 and Z' point 305 in FIG. The sensor 16 outputs a detection signal when the movable element 14 passes through its installed and fixed point.

In FIGS. 5 to 7, the movable element 14 is now at an arbitrary point 306, and the drive system power is suddenly cut off due to a power outage.
Suppose that the power is then restored. In this case, unless the position of the arbitrary point 306 is known, the work interrupted due to the power outage cannot be restarted from the interrupted position. Therefore, first, the value of the counter circuit 17 is cleared to O. Next, the drive system is moved toward the origin mark 301. As it moves, the movable element 14 eventually reaches the installation position (3) of the sensor 16.
point), and the sensor 16 outputs a detection signal. After that, when the rotary encoder 12 continues to move, it detects a Z phase detection window, that is, two points 302. These two points are 30
2 is NG device I! (not shown), it is recognized that these are the first two points after receiving a detection signal from the sensor 16. At this point, battery backup memory 1
8, the value of the displacement amount 303 stored before the power outage is read out, and the movable element 14 is further moved in the same direction by that amount to complete the return to the origin.

Then, the absolute value of the counter circuit 17 at that time is the position of an arbitrary point (point N) 306 after the power is restored (at the time of the power cut).

Therefore, after returning to the origin, the work interrupted due to the power outage can be resumed from the interrupted position based on the absolute value of the counter circuit 17.

[Problem to be solved by the invention]

However, in such conventional coordinate detection methods, the machine coordinates and workpiece coordinates have a fixed relationship, that is, (workpiece coordinates)
= (mechanical coordinates) + (constant) (in other words, displacement l303
cannot be applied unless (is constant). Therefore, for example, if a user sets a workpiece while ignoring the machine origin 301, or in a machine tool that uses a method in which the relationship between workpiece coordinates and machine coordinates differs each time the workpiece is set, return to the origin cannot be performed. For this reason, there is a problem in that coordinates cannot be detected immediately after the power is restored (when the power is turned off), and it becomes impossible to continue the work after the power is restored.

The purpose of the present invention is to provide a power source that can be used even when an operator sets a workpiece while ignoring the machine origin, or where the workpiece is set in such a way that there is no fixed relationship between the machine coordinates and the workpiece coordinates. It is an object of the present invention to provide a coordinate detection device for an NC servo motor drive system, which allows easy continuation of work interrupted due to power cutoff after recovery.

[Means to solve the problem]

The above object is to provide a coordinate detection device for an NC servo motor drive system that detects coordinates using a rotary encoder connected to a drive motor. A movable element that moves on the ball, a rail-shaped stand provided in parallel with the ball cage, and a sensor that can be placed at any position on this stand and detects that the movable element is nearby. Then, this sensor is placed at an arbitrary position on the table, and when the movable element passes near the sensor placed on the table, the sensor detects the movable element and the sensor is placed on the movable element. a sensor installation 1 collecting means for collecting the sensor, and a battery backup memory for storing the amount of displacement from the reference position of the rotary encoder to the workpiece origin set as the machine origin; This is achieved by allowing the NC servo motor drive system to return to the mechanical origin based on the stored value and the mounting position of the sensor detected by the rotary encoder.

[Effect]

The mover moves on the ball screw as the ball screw rotates. The sensor can be placed at any position on a rail-shaped stand provided in parallel with the ball cage, and detects when the movable element is nearby. The sensor installation 2 recovery means places the sensor at an arbitrary position on the table, and when the movable element passes near the sensor placed on the table, the sensor detects the movable element, and the sensor is transferred to the movable element. be collected by. The battery backup memory stores the amount of displacement from the reference position of the rotary encoder to the workpiece origin set as the machine origin. As a result, the return of the NC servo motor drive system to the mechanical origin after recovery from a power-off is performed based on the value stored in the battery backup memory and the mounting position of the sensor detected by the rotary encoder. It becomes possible. Therefore, even if the operator sets the workpiece while ignoring the machine origin, or even if the workpiece is set in such a way that there is no fixed relationship between the machine coordinates and the workpiece coordinates, after the power is restored, the It becomes possible to easily continue the work that was interrupted due to the disconnection.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an embodiment of a coordinate detection device for an NC servo motor drive system according to the present invention.
5 and 17 are the same as in FIG. 14 and 16
Although FIG. 5 also shows a movable element and a sensor, the present invention is constructed as follows. That is, the mover 14 is
It includes a piston 19 using air pressure, oil pressure, etc. whose vertical movement is controlled by a controller (not shown). In addition, the sensor 16 is provided in the sensor house 20 here, and can be placed at any position on a rail-shaped stand 21 provided in parallel to the ball screw 13, and can be recovered from that placement position. It is. Similarly to FIG. 5, 18 also indicates a battery backup memory that stores the amount of displacement from the reference position of the rotary encoder 12 to the mechanical origin, but in the present invention, the mechanical origin is the mechanical origin itself as in the case of the conventional device. Rather, it refers to the workpiece origin set as the machine origin, and therefore actually stores the amount of displacement from the reference position of the rotary encoder 12 to the workpiece origin.

The sensor (sensor house) installation 9 collection means for installing and retrieving the sensor 16 is composed of a controller (not shown) that controls the piston 19, the sensor house 20, etc. based on signals from the sensor 16 and an NC device (not shown). has been done. This controller may also be used as an NC device.

FIG. 2 is a diagram for explaining the operation of the device of the present invention that can detect the workpiece coordinates of the movable element 14 after the power is restored even if the workpiece origin does not have a certain relationship with the machine origin. FIG. 3 is a diagram showing each position of a mechanical origin and the like on a virtual scale.

In the device of the present invention, the sensor 16 is installed in a movable type that can be freely changed on the virtual scale 15, instead of the fixed type in the conventional device. In this method, first the workpiece origin is determined. Once the workpiece origin is determined, (@machine origin) =
The machine origin is determined by the relationship (workpiece origin).

Similarly to FIG. 7, the displacement amount 3 from the mechanical origin 1 to point 2 of the Z-phase detection window of the encoder 12, indicated by the triangular mark (△) in the figure, is taken into the battery backup memory 18. Then, a movable sensor 16 is installed at an arbitrary position between the two points 2 and the two points detected again after one rotation from there, that is, the Z' point 5. Incidentally, if the rotary encoder 12 is the same as that shown in FIG. 5, the displacement amount 4 between z and z' will be the same as the displacement amount 304 in the same figure.

Detection of the coordinates (arbitrary point (N) 6) after the power is restored after a power cut due to a power outage or the like can be performed in the same manner as in the conventional fixed sensor method.

That is, in FIGS. 1 and 2, it is assumed that the movable element 14 is now at an arbitrary point 6, and the drive system power is suddenly cut off due to a power outage, and then the power is restored.

In this case, unless the position of the arbitrary point 6 is known, the work interrupted due to the power outage cannot be resumed from the interrupted position. Therefore, first, the value of the counter circuit 17 is cleared to 0. Next, the drive system is moved toward the origin mark 1. As it moves, the movable element 14 eventually reaches the installation position (three points) of the sensor 16, and the sensor 16 outputs a detection signal. After that, when the movement continues, the rotary encoder 12 detects the Z phase detection window, that is, two points 2. These two points 2 are recognized by the NC device (not shown) as the first two points after receiving a detection signal from the sensor 16. At this point, battery backup memory 1
8, the value of the displacement i13 stored before the power outage is read out, and the movable element 14 is further moved in the same direction by that amount to complete the return to the origin. Then, the absolute value of the counter circuit 17 at that time is the position of an arbitrary point (N point) 6 after the power is restored (when the power is turned off).

Next, how do we move the sensor 16 to reach the two points 2 and Z?
The following describes how to install the sensor 16 at an arbitrary position between the sensor 16 and the point 5, and how to recover the sensor 16.

3 is a sectional view of FIG. 1 viewed from the direction of the arrow, and FIG. 4 is a diagram showing an example of the configuration of the sensor house 20. Hereinafter, referring to these figures, the sensor 16, that is, the sensor house 2
The installation and retrieval of 0 and the operation of the sensor house 20 will be explained.

In FIG. 3, the movable element 14 is moved by the ball screw 13 in a direction perpendicular to the plane of the figure (in the direction of the arrow A1 in FIG. 1). The piston 19 is attached to the movable element 14, and the third
In the figure, it works in the vertical (arrow 2) direction. Reference numeral 21 denotes a stand on which the sensor house 20 is placed, and this stand 21 and the piston 19 are made of a ferromagnetic material capable of magnetic attraction, such as iron.

FIG. 3(A) is a diagram showing a standby state of the sensor house 20 before a machining (work) program starts. This (A
) In the state shown in the figure, the switch movable body 401 of the sensor house 20 is pushed in by the piston 19, so the second fixed contact 404 and the movable contact 403 come into contact, and current flows through the coils 405 and 406, which are excited. , is attracted to the piston 19 against the biasing force of the spring 413.

Here, 409 is a DC power supply, and 410 is a current limiting variable resistor. 411 is a relay contact (B contact), which is controlled to open and close depending on the energized state of the relay coil 412, (A)
In the state shown in the figure, the relay coil 412 is in a non-energized state and is closed.

Now, assume that on the NC machine tool side, the workpiece has been set and each axis is at the workpiece origin. The work program is started, the machine origin setting described above begins, and the sensor 16 is installed. At that time, the mover 14 moves between the two points 2 and Z'
It moves to predetermined sensor 16 installation points (three points) while decelerating between points 5 and 3, and a controller (not shown) energizes the coil 412 to open the relay contact 411. As a result, the power supply to the coils 405 and 406 of the sensor house 20 is cut off, and the cores 407 and 408 are demagnetized. In addition,
The other end side of the spring 413 whose one end side is supported by the base metal 414 (
The switch movable body 401 protrudes upward due to the pressing force in the upward direction (in the figure). Due to the pressing force of the slide movable body 401, the sensor house 20 falls vertically from the piston 19 onto the stand 21. This causes the controller to connect relay contact 4 again.
11 is closed. At this time, since the switch movable body 401 protrudes upward, the movable contact 403 connected to the switch movable body 401 is in contact with the first fixed contact 402 . Therefore, coil 415 is energized and core 4
16 is excited, and the sensor house 20 is attracted to the stand 21 (see FIGS. 3(B) and 4).

In this case, since the sensor 16 is housed in the sensor house 20, the sensor 16 is installed. Although the sensor 16 is a reflective type optical sensor in the illustrated example, it may be a sensor of another type, such as a light transmission type.

Once the sensor 16 is installed, the work program is put into operation. If a power outage occurs during program execution, the program operates as described above.

When the program is completed, the movable element 14 returns to the workpiece origin by -degrees. At this time, the piston 19 is stopped once at the location where the sensor 16 is installed, and then the controller lowers the piston 19 as shown by the arrow H by sequence control (see FIG. 3(C)). Since the switch movable body 401 is pushed down by the piston 19 as shown by the arrow, the movable contact 403 comes into contact with the second fixed contact 404 again (see arrow T), the cores 407 and 408 are excited, and the sensor house 20 is activated. At the same time as the core 416 is attracted to the piston 19, the core 416 is demagnetized. Then, the piston 19 is raised again, and the actuator 14 returns to the standby position while adsorbing the sensor house 20, resulting in the standby state shown in FIG. 3(A).

〔Effect of the invention〕

According to the present invention, even if there is no fixed relationship between the workpiece origin and the machine origin, in other words, even if the operator sets the workpiece while ignoring the machine origin, the If this occurs, the workpiece coordinates can be tilted easily and accurately after the recovery, and the work that was interrupted due to the power outage can be easily continued.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of the device of the present invention, and FIG.
The figure shows each position of the machine origin on the virtual scale in Figure 1, Figure 3 is a diagram explaining the installation and recovery of the sensor house in Figure 1, and the operation of the sensor house. 1st
Figure 5 is a schematic diagram of the conventional device; Figure 6 is an explanatory diagram of the encoder in Figure 5; Figure 7 is on the virtual scale in Figure 5. FIG. 3 is a diagram showing various positions such as a machine origin. 1, 201, 301... Machine origin (origin mark), 2
, 202.203...2 points, 3.203,303...
・Angular displacement or amount of angular displacement from the machine origin to two points, 4.2
04.304...Angular displacement or angular displacement amount from 2 points to 2 points, 5°305...Z' point, 6,306...Any point N, 11...Drive motor, 12. ...Rotary encoder, 13...Ball screw, 14...Movable element,
15... Virtual scale, 17... Counter circuit, 1
8...Battery backup memory, 19...
Piston, 20...sensor house, 21...unit, 4
01... Switch movable body, 402.403.404.
...Contact, 405°406.412.415...Coil, 407,408.416...Core, 409...
- DC power supply, 410... variable resistor, 411... relay contact, 413... spring, 414... base metal.

Claims (1)

[Claims] 1. In a coordinate system of an NC servo motor drive system that detects coordinates using a rotary encoder connected to a drive motor, the rotary encoder is screwed onto a ball screw connected to the drive motor and moves on the ball screw as the ball screw rotates. A movable element, a rail-shaped stand provided in parallel with the ball screw, a sensor that can be placed at any position on the stand and detects that the movable element is nearby, and a sensor that detects that the movable element is nearby. Sensor installation in which the sensor is placed at an arbitrary position on the table, and when the movable element passes near the sensor placed on the table, the sensor detects the movable element and the sensor is collected by the movable element. , a collection means, and a battery backup memory that stores the amount of displacement from the reference position of the rotary encoder to the workpiece origin set as the machine origin, and the stored value of the battery backup memory and the rotary encoder The NC is characterized in that it is possible to return the NC servo motor drive system to the mechanical origin based on the mounting position of the sensor detected by the
Coordinate detection device for servo motor drive system.