Principles of CNC machining
Release date:2022-07-01
⑵ CNC unit CNC unit is the core of CNC machine tools, and it consists of three parts: input, processing, and output of information. The CNC unit receives digital information, which is decoded, interpolated, and logically processed by the control software and logic circuit of the CNC device. After that, various instruction information is output to the servo system, which drives the executing components for feed motion.
⑶ Input/Output Equipment The input device transmits various processing information to external devices of the computer. In the early days of the emergence of CNC machine tools, the input device was perforated paper tape, which has now been phased out. Later, it developed into cassette tapes, and then developed into portable hardware such as keyboards and disks, greatly facilitating information input work. Now, DNC network communication serial communication is commonly used for input. Output refers to the output of internal working parameters (including original parameters under normal and ideal working conditions of the machine tool, fault diagnosis parameters, etc.). Generally, these parameters need to be recorded and saved in the initial working state of the machine tool. After working for a period of time, the output can be compared and compared with the original data to help determine whether the machine tool is operating normally.
The servo unit is composed of a driver and a driving motor, and together with the execution components and mechanical transmission components on the machine tool, it forms the feed system of the CNC machine tool. Its function is to convert pulse signals from CNC devices into the motion of moving parts of the machine tool. For stepper motors, each pulse signal causes the motor to rotate through an angle, which in turn drives the moving parts of the machine tool to move a small distance. Each executing component of the feed motion has a corresponding servo drive system, and the performance of the entire machine tool mainly depends on the servo system.
The driving device of the driving device converts the amplified command signal into mechanical motion, and drives the machine tool through simple mechanical connection components to accurately position the workbench or perform strict relative motion according to the specified trajectory, and finally process the parts required by the drawing. Corresponding to the servo unit, the driving devices include stepper motors, DC servo motors, and AC servo motors. The servo unit and driving device can be collectively referred to as the servo drive system, which is the power device for machine tool operation. The instructions of CNC devices rely on the servo drive system to be implemented. Therefore, the servo drive system is an important component of CNC machine tools.
Programmable Controller (PC) is a general-purpose automatic control device based on a microprocessor, designed specifically for application in industrial environments. Since the initial development of this device was aimed at solving the logic and switch control of production equipment, it is called a Programmable Logic Controller (PLC). When a PLC is used to control the sequential actions of a machine tool, it can also be called a Programmable Machine Controller (PMC). PLC has become an indispensable control device for CNC machine tools. CNC and PLC coordinate and cooperate to jointly complete the control of CNC machine tools.
Measurement feedback device, also known as feedback element, includes grating, rotary encoder, laser rangefinder, magnetic grating, etc. Usually installed on the workbench or screw of a machine tool, it converts the actual displacement of the workbench into an electrical signal and feeds it back to the CNC device, which compares it with the command value to generate an error signal to control the machine tool to move in the direction of eliminating this error. 2. When using CNC machine tools, the first step is to write the geometric information and process information of the machined part drawings into a machining program using the prescribed code and format; Then input the machining program into the CNC device, and according to the program requirements, process and allocate information in the CNC system to move each coordinate by several minimum displacements, achieving relative motion between the tool and the workpiece, and completing the machining of the parts.
Dongguan Fuding Metal Co., Ltd. was established in 2006 and is a professional factory for polishing automotive parts and processing aluminum profile products. It also provides surface treatment services for copper, aluminum, zinc, stainless steel and other hardware products such as casting, forging, die-casting, CNC turning and milling precision processing, stamping, precision pipe bending, welding and sandblasting, electroplating, oil spraying, anode, etc. Based in the surface treatment industry with high requirements for product quality and integrity.