JPH0863212A - Origin return system for cnc - Google Patents

Abstract

PURPOSE: To enable an origin return which does not require a speed reduction switch as to the origin return system for CNC for confirming the origin position of a table at the start of machining. CONSTITUTION: An absolute position detecting means 5 receives the absolute position signal from an absolute pulse coder 4, outputs a speed reduction start position signal when the table 1 reaches a speed reduction start position for the origin return, and outputs a speed reduction period end position signal when the table reaches a speed reduction period end position. An origin return control means 6 outputs an origin return command when the power source is turned ON, outputs a speed reduction command when the speed reduction start position signal is inputted, and outputs a movement stop command at the timing of a 1st reference signal after the speed reduction period end position signal is inputted. A shaft movement control means 7 performs movement control over a servomotor 3 in the origin return direction by inputting the origin return command, reduces the speed of the movement of the servomotor 3 by inputting the speed reduction command, and stops the movement of the servomotor 3 by inputting the movement stop command.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CNC origin return method for confirming the origin position of a table at the start of machining, and more particularly to a CNC origin return method in a full-closed system.

[0002]

2. Description of the Related Art Conventionally, when performing a home return of a table of a machine tool controlled by a CNC, a linear scale attached to the table, a pulse coder for detecting the speed of a servo motor for moving the table, and an origin of the table. A deceleration switch provided in the vicinity and a dog for pushing the deceleration switch by a predetermined moving distance are required.

In this origin return method, while the axis is moved in the direction of the origin, a grid signal is virtually generated within the CNC at intervals of the reference signal based on the reference signal for absolute position confirmation of the linear scale and the signal of the pulse coder. When the deceleration switch is turned on, the axis feed speed is decelerated only while it is turned on, and when the deceleration switch is turned off again, the axis movement is stopped at the timing of the grid signal immediately after that and the position is recognized as the origin. Was doing.

[0004]

However, in such a system, since the deceleration switch is required, the labor and cost for mounting are increased.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a home position return system for a CNC which does not require a speed reduction switch.

[0006]

According to the present invention, in order to solve the above-mentioned problems, in a home position return method of a CNC for confirming a home position of a table at the start of machining, a movement amount of the table attached to the table is set. A linear scale that outputs a pulse signal with a minute interval according to the above and a reference signal with an interval sufficiently larger than the pulse signal, and an absolute pulse that outputs an absolute position signal by detecting the absolute position of the servo motor that moves the table. With a coder,
An absolute position that receives an absolute position signal from the absolute pulse coder, outputs a deceleration start position signal when the table reaches the deceleration start position for origin return, and outputs a deceleration period end position signal when the table reaches the deceleration period end position. An origin return command is output when the power is turned on, a deceleration command is output when the deceleration start position signal is input, and a movement stop command is output at the timing of the first reference signal after the deceleration period end position signal is input. And a home position return control unit for outputting the home position return command to control the movement of the servo motor in the home position return direction, inputting the deceleration command to decelerate the movement of the servo motor, and inputting the movement stop command. Axis movement control means for stopping the movement of the servomotor according to C.
An NC return to origin method is provided.

[0007]

[Function] The linear scale attached to the table
A pulse signal with a minute interval according to the amount of movement of the table and a reference signal with an interval sufficiently larger than this pulse signal are output. On the other hand, the absolute pulse coder detects the absolute position of the servo motor that moves the table and outputs an absolute position signal. The absolute position detection means receives the absolute position signal from the absolute pulse coder, outputs the deceleration start position signal when the table reaches the deceleration start position for origin return, and outputs the deceleration period end position signal when it reaches the deceleration period end position. Output.

The origin return control means outputs an origin return command when the power is turned on, outputs a deceleration command when a deceleration start position signal is input, and moves at the timing of the first reference signal after the deceleration period end position signal is input. Output a stop command. The axis movement control means controls the movement of the servo motor in the direction of returning to the origin in response to the input of the origin return command, decelerates the movement of the servo motor in response to the input of the deceleration command, and stops the movement of the servo motor in response to the input of the movement stop command.

[0009]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the concept of the function of one embodiment of the present invention. Linear scale 2 attached to table 1
Outputs a pulse signal with a minute interval and a reference signal with an interval sufficiently larger than this pulse signal according to the amount of movement of the table. On the other hand, the absolute pulse coder 4 detects the absolute position of the servo motor 3 that moves the table 1 and outputs an absolute position signal. The absolute position detection means 5 receives the absolute position signal from the absolute pulse coder 4, outputs the deceleration start position signal when the table 1 reaches the deceleration start position for origin return, and ends the deceleration period when it reaches the deceleration period end position. Output position signal.

The origin return control means 6 outputs an origin return command when the power is turned on, outputs a deceleration command when the deceleration start position signal is input, and outputs the deceleration period end position signal at the timing of the first reference signal. Outputs a movement stop command. The axis movement control means 7 controls the movement of the servomotor 3 in the direction of returning to the origin by the input of the origin return command, decelerates the movement of the servomotor 3 by the input of the deceleration command, and moves the servomotor 3 by the input of the movement stop command. To stop.

FIG. 2 is a block diagram showing the hardware of a numerical controller (CNC) for implementing the present invention.
The processor (CPU) 11 controls the entire numerical controller according to a system program stored in the ROM 12. EPROM or EEPROM is used for the ROM 12. A DRAM is used as the RAM 13 and stores various data. The non-volatile memory 14 stores a processing program 14a, parameters 14b and the like. The non-volatile memory 14 also stores deceleration start position data, deceleration period end position data, and the like, which will be described later. Since the battery-backed CMOS or the like is used for the non-volatile memory 14, the contents thereof are retained even after the power of the numerical control device is cut off.

A PMC (Programmable Machine Controller) 15 receives commands for M functions, T functions, etc., converts them into signals for controlling a machine tool by a sequence program 15a, and outputs the signals. Further, a limit switch signal from the machine side or a switch signal from the machine operation panel is received and processed by the sequence program 15a, and necessary signals are stored in the RAM 13 via the bus and read by the processor 11.

Graphic control circuit (CRTC) 16
Converts the data such as the current position and movement amount of each axis into a display signal and sends it to the display device 16a. The display device 16a displays this display signal. A CRT, a liquid crystal display device, or the like is used as the display device 16a. The keyboard 17 is used to input various data.

Upon receiving the position command from the processor 11, the axis control circuit 18 outputs a speed command signal for controlling the servo motor 20 to the servo amplifier 19. The servo amplifier 19 amplifies this speed command signal and drives the servo motor 20.

The input / output circuit 23 is connected to a control circuit on the machine side and exchanges input / output signals with the machine side. That is, the limit switch signal on the machine side and the switch signal on the machine operation panel are received, and the PMC 15 reads them. Also,
It receives a control signal for controlling the pneumatic actuator on the machine side from the PMC 15 and outputs it to the machine side.

The manual pulse generator 24 outputs a pulse train for precisely moving each axis according to the rotation angle, and is mounted on the machine operation panel. Ball screw 2 for servo motor 20
6 are joined, and the ball screw 26 also rotates according to the rotation of the servomotor 20. The ball screw 26 has
A machine-side table 25 that moves according to the rotation is provided. In this embodiment, only the X axis is shown.

The servo motor 20 has an absolute pulse coder 20a built therein.
The absolute position signal of the axis is detected and the absolute position signal is detected.
Send to 8. This absolute pulse coder 20a
It is backed up by a battery and holds the detected absolute position even after the power is turned off.

A linear scale 21 is attached to the table 25. The linear scale 21 includes a scale 21a and a sensor 21b. The scale 21a is movably attached together with the table 25, and the sensor 21b is fixed to the table side. Sensor 21
b feeds back a pulse signal with a minute interval to the axis control circuit 18 according to the amount of movement of the scale 21a. Also,
The sensor 21b outputs a reference signal at relatively large intervals, for example, every 5 mm.

The axis control circuit 18 detects the current position of the table 25 based on the pulse signal and the reference signal from the sensor 21b. The pulse signal, the reference signal, and the absolute position signal are sent from the axis control circuit 18 to the processor 11 via the bus. When the power is turned on, the processor 11 performs origin return control, which will be described later, based on the pulse signal, the reference signal, and the absolute position signal.

These elements are required for the number of axes, but since the configuration of each element is the same, only one axis is described here. Further, in the figure, a spindle control circuit for controlling the spindle, a spindle amplifier, a spindle motor, etc. are omitted.

Next, a specific procedure of the origin return method by the numerical controller having such a configuration will be described. FIG.
FIG. 6 is a diagram showing a specific procedure of an origin return method according to an embodiment of the present invention. First, when the power is turned on, the processor 1
1 controls the servo motor 20 of each axis to start the origin return operation. After starting the home-return operation, the processor 1
When No. 1 receives the first reference signal from the sensor 21b of the linear scale 21 (time t ₀ ), from that time point, the grid signal is generated at the same intervals as the reference signal.

The absolute pulse coder 20
When a deceleration start position set in advance is detected (time t ₁ ), the feed rate of the axis is decelerated. Then, when the absolute pulse coder 20a is likewise detects a deceleration period end position set in advance (time t _2), upon the occurrence of the first grid signal from the deceleration period end position (time t _3), the feed axis The speed is set to 0 and the movement is stopped. Thus, by recognizing the position of each axis at this point as the origin, the origin returning operation is completed. After that, the current position of the table 25 can always be accurately grasped by counting up each time the pulse signal of the linear scale 21 is input.

FIG. 4 is a flow chart showing the procedure on the processor 11 side for the origin return in such an embodiment of the present invention. [S1] The axis is moved to start the origin return operation. [S2] It is determined whether or not a reference signal is input from the linear scale 21, and if so, the process proceeds to step S3, and if not, step S2 is repeated. [S3] A grid signal is generated based on the reference signal. [S4] It is determined whether or not the detected position of the absolute pulse coder 20a has reached the deceleration start position. If not, the process proceeds to step S5, and if not, step S4 is repeated. [S5] The deceleration of axis movement is started. [S6] It is determined whether or not the detected position of the absolute pulse coder 20a has reached the deceleration period end position. If not, the process proceeds to step S7, and if not, step S6 is repeated. [S7] It is determined whether or not a grid signal is generated for the first time from the deceleration period end position. If it is generated, the process proceeds to step S8, and if not, step S7 is repeated. [S8] The movement of the axis is stopped.

As described above, in this embodiment, the absolute pulse coder 2 is used as the position detector of the servomotor 20.
Since 0a is used and the home position return is performed based on the absolute position detection signal, it is possible to perform deceleration stop without providing a deceleration switch or dog as in the conventional case. Therefore, manufacturing cost and the like can be reduced.

In this embodiment, the linear scale 21
Although the grid signal is generated based on the reference signal of, the reference signal may be used only. Next, another embodiment of the present invention will be described.

FIG. 5 is a diagram showing the concept of the function of this embodiment. Linear scale 32 attached to table 31
Outputs a pulse signal with a minute interval according to the movement amount of the table 31 and a reference signal with an interval sufficiently larger than the pulse signal. On the other hand, an absolute pulse coder 34 built in the servo motor 33 that moves the table 31.
Detects the absolute position of the servo motor 33 and outputs an absolute position signal. The position correction means 35 outputs an axis movement start command when the power is turned on, and the axis movement control means 36 controls the movement of the servomotor along with the input of this axis movement start command. The position correction means 35 corrects the CNC coordinate system based on the absolute position of the absolute pulse coder and the timing of the reference signal when the first reference signal is input from the start of axis movement.

Next, a specific procedure of this embodiment will be described.
However, since the hardware configuration of this embodiment is almost the same as that of FIG. 2, the description thereof is omitted here. FIG. 6 is a diagram showing a specific procedure of the origin return method of this embodiment. Normal,
When the work is stopped and the power is turned off, the coordinates based on the linear scale up to that point are lost, but the position of the table 25 is slightly deviated due to backlash of each mechanism. Further, this shift amount is sufficiently small with respect to the interval of the reference signal. Therefore, when the power is turned on again, the absolute position of the table 25 recognized by the absolute pulse coder 20a has a value different from the actual position of the table 25. Here, for example, the absolute pulse coder 2
0a coordinates 5mm, 10mm, 15mm, 20mm, 2
The power is cut off in a state where each position of 5 mm coincides with the reference signal of the linear scale 21, and when the power is subsequently turned on, the coordinates on the table 25 side are slightly shifted in the negative direction. .

When the power is turned on, the processor 11 side recognizes the absolute position P ₀ (for example, 15 mm) by the absolute pulse coder 20a at that time.
Also, the axis is moved by the coordinate system based on it. For example, when the reference signal rises while moving the axis in the positive direction, the processor 11 determines that the coordinate value of the linear scale 21 closest to the coordinate value of the absolute position P ₁ by the absolute pulse coder 20a should be raised. By (15 mm), the coordinate system based on the absolute pulse coder 20a up to then is corrected (P ₁ = 15 mm). After that, the axis is moved in the corrected coordinate system. Thereby, the coordinate system of the CNC and the coordinate system of the linear scale 21 can be matched.

FIG. 7 is a flow chart showing the procedure on the processor side according to another embodiment of the present invention. Note that this flowchart is started when the power is turned on. [S10] The axis starts moving. [S11] It is determined whether or not the reference signal has risen. If it rises, the process proceeds to step S13, and if not, step S12 is repeated. [S12] The coordinate system based on the absolute pulse coder 20a is corrected based on the reference signal of the linear scale 21.

As described above, in this embodiment, when the axis is moved after the power is turned on and the reference signal first rises, the absolute pulse coder 20a is based on the reference signal.
Since the coordinate system according to is corrected so that the coordinate system of the CNC and the coordinate system of the linear scale 21 coincide with each other, it is not necessary to move the axis to the origin when the power is turned on. Therefore, it is possible to return to the origin more quickly.

[0031]

As described above, according to the present invention, a pulse signal having a minute interval according to the movement amount of the table and a linear scale for outputting a reference signal having an interval sufficiently larger than the pulse signal are attached to the table. An absolute pulse coder that detects the absolute position of the servo motor that moves the motor and outputs an absolute position signal is provided.When the power is turned on, the servo motor is controlled to move in the home return direction, and when the table reaches the deceleration start position for home return. Since the movement of the servo motor is decelerated and the movement of the servo motor is stopped when the position reaches the deceleration period end position, deceleration stop can be performed without providing a deceleration switch or dog. Therefore, manufacturing cost and the like can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a functional concept of an embodiment of the present invention.

FIG. 2 is a numerical controller for implementing the present invention (CN
It is a block diagram which shows the hardware of C).

FIG. 3 is a diagram showing a specific procedure of an origin return method according to an embodiment of the present invention.

FIG. 4 is a flowchart showing a procedure on the processor side for origin return according to an embodiment of the present invention.

FIG. 5 is a diagram showing a concept of functions of another embodiment.

FIG. 6 is a diagram showing a specific procedure of a return to origin method according to another embodiment.

FIG. 7 is a flowchart showing a procedure on the processor side according to another embodiment of the present invention.

[Explanation of symbols]

 1 table 2 linear scale 3 servo motor 4 absolute pulse coder 5 absolute position detection means 6 origin return control means 7 axis movement control means 11 processor 12 ROM 13 RAM 14 non-volatile memory 18 axis control circuit 19 servo amplifier 20 servo motor 20a absolute pulse Coder 21 Linear scale 21a Scale 21b Sensor 25 Table

Claims (4)

[Claims] 1. A CNC origin return method for confirming the origin position of a table at the start of machining, the pulse signal being attached to the table and having a minute interval according to the movement amount of the table, and the pulse signal being more sufficient than the pulse signal. A linear scale that outputs a reference signal with a large interval, an absolute pulse coder that outputs an absolute position signal by detecting the absolute position of the servo motor that moves the table, and an absolute position signal from the absolute pulse coder, Absolute position detection means that outputs a deceleration start position signal when the table reaches the deceleration start position for origin return, and outputs a deceleration period end position signal when the table reaches the deceleration period end position, and outputs an origin return command when the power is turned on. However, a deceleration command is output when the deceleration start position signal is input, and the deceleration period end position signal is output. The origin return control means that outputs a movement stop command at the timing of the first reference signal after the input of, and the movement control of the servo motor in the origin return direction by the input of the origin return command, and the input of the deceleration command. Axis return control means for decelerating the movement of the servo motor and stopping the movement of the servo motor by the input of the movement stop command. 2. The origin return control means is configured to virtually generate grid signals at the same intervals as the reference signal after the first input of the reference signal from the start of the origin return operation. The method for returning to origin of a CNC according to claim 1, wherein. 3. A CNC origin return method for confirming the origin position of a table at the start of machining, in which a pulse signal attached to the table and having a minute interval according to the movement amount of the table and the pulse signal are more sufficient than the pulse signal. , A linear scale that outputs a reference signal with a large interval, an absolute pulse coder that detects the absolute position of the servo motor that moves the table and outputs an absolute position signal, and an axis movement start command is output when the power is turned on. Position correction means for correcting the coordinate system of the CNC based on the absolute position of the absolute pulse coder and the timing of the reference signal when the reference signal is input for the first time from the start of the axis movement; And a shaft movement control means for controlling the movement of the servomotor. Homing scheme. 4. The position correction means, when the reference signal first rises from the start of the axial movement, the position of the absolute pulse coder that matches the reference signal before the start of the axial movement is the position of the absolute pulse coder. A CNC origin return method, characterized in that it is configured to correct the coordinate system so as to match the reference signal.