Before getting acquainted with the CNC machine and the CNC operator training procedure, it is first necessary to know that CNC stands for "Computer Numerical Control". When computers are used to control a numerically controlled (NC) tool, the tool or machine is called a CNC. In other words, if we use a computer to control machine tools such as lathes, mills, grooves, shapers, etc., they are called CNC machines.
CNC cutting operations are called CNC machining. Various machining services in which CNC machine is used are known as CNC machining services. Usually, in the CNC machine, programs are first designed or prepared and then given to the CNC machine. According to these programs, CNC controls the movement and speed of machine tools.
The parts of a CNC device
(a) Input devices: are the devices used to input the program into the CNC machine. Usually, three input devices are used, which are punch tape reader, magnetic tape reader and computer through RS-232-C communication. (b) Machine control unit (MCU):< /b> This section is the heart of the CNC machine and performs the control function of the CNC machine, the various functions of the MCU are as follows:
- Receives and reads encoded instructions.
- Decodes the encoded instruction .
- implements interpolation (linear, circular and helical) to generate axis motion commands.
- gives axis motion commands to amplifier circuits to drive axis mechanisms.
provides position and velocity feedback signals for Each axis receives stimulus.
(c) Machine tool: A CNC machine tool always has a table and a spindle for position and speed control. The machine table is controlled in the direction of the X and Y axis and the spindle in the direction of the Z axis.
(d) Driving system: The driving system of the CNC machine consists of amplifier circuits, drive motors and ball screws. has been The MCU feeds signals from each axis (i.e. position and speed) to the amplifier circuits. The control signals are then amplified to drive the drive motors. And active drive motors rotate the lead ball screw to position the machine table. (e) Feedback system: This system consists of transducers that act as sensors. . It is also called a measurement system. This section contains position and speed transducers that continuously monitor the position and speed of the cutting tool at any given moment. The MCU receives signals from these transducers and uses the difference between the reference and feedback signals to generate control signals to correct position and speed errors.
How does the CNC device work?
- First, the program is entered into the MCU.
- In the MCU, all the data processing is done, and the MCU prepares all the motion commands according to the prepared program and sends them to the driving system.
- System Driving works while motion commands are sent by the MCU. This system controls the movement and speed of the machine tool.
- The feedback system records the measurement of the position and speed of the machine tool and sends a feedback signal to the MCU.
- In the MCU, the feedback signals are compared with the reference signals and in If there is an error, it corrects it and sends new signals to the device for the correct tool.
- A display unit is used to see all commands, programs and other important data and acts as the eye of the device.