JPS62187906A - Numeral control method - Google Patents

Abstract

PURPOSE:To attain control based upon a real value by detecting driving force or load actually inputted to a driving source by sensors. CONSTITUTION:A machine tool is constituted by moving a machine table 1 by a hydraulic cylinder 2 and cutting off a work on the table 1 by a tool 3a driven by a main spindle motor 3. In addition, a position detecting sensor 5, a speed control for controlling a servo valve 2a on the basis of a command outputted from a numeral control part 4, a pressure sensor 7, and a current sensor 8 for detecting the load current of the main spindle motor 3 are also formed. Data appropriate for the detecting data of the sensors 7, 8 are selected from plural acceleration/deceleration patterns set up in accordance with the capacity of pressing force or load current previously obtained by comparing the detecting data with a value indicating the pressing force of a cylinder 2 or the load current of a motor obtained at the preceding execution of test work by the numerical controller 4 to change an acceleration/deceleration pattern at the time of detection.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a numerical control method that takes into consideration the actual operating conditions of a machine.

[Conventional technology]

Conventional numerical control only has one or several types of stop-move-re-stop acceleration/deceleration pattern parameters fixed for the drive shaft to be controlled, and data indicating the actual operating state of the two machines. For example, is not used as a parameter for changing the acceleration/deceleration pattern.

That is, conventionally, for example, when the drive source of the drive shaft is a hydraulic or pneumatic cylinder, a sensor is provided to detect the operating pressure, or a sensor is provided to detect the load current of the drive motor of the cutter main shaft. The only thing that is done is to bring the machine to an emergency stop when the detected value shows an abnormality.

[Problem that the invention seeks to solve]

In conventional numerical control, parameters for acceleration/deceleration patterns are fixedly set in advance on the assumption that the rigidity of one machine, the friction of sliding parts, the output torque of the motor, etc. are constant. These unique characteristics or their numerical values are of a nature that changes from moment to moment depending on the age of one machine, the size of the load, or the speed and position of the controlled object.

In particular, high speed has become popular in recent years.

In high-precision numerical control, even if the rigidity of the machine can be increased, there is a limit to it, so the various characteristics of the machine are likely to change.

For this reason, although the numerical control itself is executed almost as planned, in reality, the output of the motor is so large that it is close to an abnormality (before the alarm means is activated), which places an unnecessary burden on the machine. These problems are often overlooked, and this often leads to decreased control accuracy and shortened machine life.

[Means for solving problems]

The present invention has been made for the purpose of providing a numerical control method that can overcome the difficulties associated with the execution of conventional numerical control methods as described above.

Its structure is based on numerical control that is executed every arbitrary sampling period by using all or part of the command values for acceleration, velocity, and position, the actual values corresponding to these, or the deviation between both values as control data. Then, for a drive source such as a motor that is driven based on the above control data, an arbitrary numerical value representing the driving force actually input to the drive source and the load actually applied to the drive source is calculated. The present invention is characterized in that a sensor is provided for detection in a sampling period to extract the actual values of the driving force and load, and the control data is changed based on the extracted actual values.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

The solid line in FIG. 1 is a machine tool in which a machine table 1 is moved by a hydraulic cylinder 2, and a workpiece (not shown) set on the table 1 is cut by a tool 3a driven by a spindle motor 3. 2 is a block diagram of an example of a control system in which the cylinder 2 is driven and controlled by a numerical control device 4. FIG. In addition, 5 is a position detection sensor for detecting the current position of the table 1, and 6 is a speed control unit that converts the position command and speed command from the numerical control device 4 into analog analog to control the operation of the hydraulic cylinder 2. Now, the servo valve 2a is controlled.

In conventional numerical control, a command signal to the speed control section 6 is formed by a position command, a position deviation based on data from the position sensor 5, and a speed command generated from this deviation.

This command is changed based on one or more parameters of an acceleration/deceleration pattern such as stop-move-re-stop that is fixed with respect to the drive shaft to be controlled.

However, with this method, regardless of the operating state of the machine, such as the magnitude of the load current of the spindle motor 3 or the magnitude of the load applied to the hydraulic cylinder, speed control is performed quickly based on the position deviation and acceleration/deceleration pattern described above. For example, high-speed feed or high-load control is performed as is, which may cause vibrations due to wear on the sliding surfaces of the machine, or may damage the fl of the tool or workpiece. Sometimes.

This is particularly likely to occur when a machine has been used for a considerable period of time and is then controlled at a speed or load that did not initially pose a problem for the machine.

Therefore, in the present invention, data representing the operating state of that part is retrieved from the machine side that is not subject to data detection for forming control command values during control execution, and based on this data, the above-mentioned conventional control is performed. By changing the acceleration/deceleration pattern, we can also detect the wear condition of the tool and abnormalities of the workpiece. Furthermore, we can independently adjust the pressure force of the cylinder 2, the rotation speed, torque, etc. of the motor 3 based on the above data. It is something that can be controlled.

In the embodiment of the present invention, in order to detect the load on the hydraulic cylinder, a pressure sensor 7 shown by a broken line in FIG. 1 is provided, and
A current sensor 8 is provided to detect the load current of the main shaft motor 3, and each sensor 7.8 is provided on the cylinder 2 and motor 3.
A unique control input is performed based on the detected value.

Therefore, the detection data of the sensor 7.8 is obtained, for example, when a test process is performed on the machine in advance,
It is compared and contrasted with the numerical values indicating the pressure force of the cylinder 2 and the load current of the motor 3 stored in the numerical control device 4, and is set corresponding to the magnitude of the pressure force and load current obtained in advance. Among the plurality of acceleration/deceleration patterns, one suitable for the detection data is selected and used to change the acceleration/deceleration pattern at the time of the detection.

In addition, the detection data of the sensor 7.8 can be used, for example, to increase the rotation speed or torque of the main shaft motor 3, or to increase the pressurizing force of the hydraulic cylinder 2, within a range that does not cause any trouble to the machine. can.

〔Effect of the invention〕

In this way, in the present invention, data is added based on data detected from the driving parts that represents the operating state of the machine.

By changing the reduction pattern or changing the output of the drive source, faster and more accurate numerical control becomes possible.

In particular, the present invention detects the operating state of a machine, which changes due to aging of the machine, the magnitude of load and speed, or the position of the positioning target, using data for numerical control in conventional control. By detecting data about the drive parts that do not work, the control program can be set and changed within an allowable range in response to the operating state of the machine at that time, allowing for faster and more accurate operation. Control becomes possible.

[Brief explanation of drawings]

FIG. 1 is a control block diagram for implementing the method of the present invention.

Claims (1)

[Claims] In numerical control that is executed every sampling period by using all or part of command values for acceleration, velocity, and position and their corresponding actual values, or the deviation of both values as control data, the above control For a drive source such as a motor that is driven based on data, the numerical values representing the driving force actually input to the drive source and the load actually applied to the drive source are detected at any sampling period. A numerical control method characterized in that a sensor is provided to extract the actual values of the driving force and load, and the control data is changed based on the extracted actual values.