A CNC machine is composed of more than 1000 parts, which can be roughly divided into 5 systems. Next, we take the standard 3-axis vertical milling machine as an example to get a general idea of the composition of a CNC machine tool through these 5 systems.
1. CNC system
The CNC system is the brain of the CNC machine, which is used to control and monitor the operation of the whole machine. It consists of two parts: software and hardware, the software includes operating system, code interpreter and control program, which is used to parse the G-code, generate control instructions, control the tool movement, adjust the spindle speed, and receive sensor data such as tool position/temperature in real time, automatically correct the error, and ensure the accuracy of machining; The hardware includes processors, motor drivers and sensors, which are responsible for the calculation and acquisition of data. These two parts are like the relationship between the Windows system and the computer hardware.
2. Mechanical systems
The mechanical system is the skeleton of the CNC machine, which is the carrier of the movement of the tool and the workpiece, in which the bed serves as the base to provide stable support for the spindle, guide rail, lead screw, workbench and transmission mechanism installed on it, and reduce the vibration during the machining process. The spindle drives the tool to rotate, and the lead screw drives it along the guide rail precisely to cut the workpiece fixed on the table.
3. Drive system
The drive system is composed of servo motor and spindle motor, which is the heart of CNC machine tools, in which the servo motor is used to drive the spindle to move upward in the X, Y, and Z axes, and the spindle motor is used to drive the rotation of the tool, and the two cooperate to complete the cutting.
4. Tooling system
The machining process of a part involves a variety of operations, including milling plane, chamfering, drilling and tapping, etc., each operation corresponds to a specially designed tool, if the tool is changed manually, it will greatly reduce the processing efficiency and affect the machining accuracy. So the engineers designed the tool magazine: for storing and managing multiple tools, and the automatic tool change system (ATC): for automatic tool change. The tool system, the tool magazine and the automatic tool changer make up the tool system.
5. Assistance systems
The main role of the auxiliary system is cooling and lubrication. The circulating cooling system is the most commonly used cooling method, which reduces the cutting temperature by spraying coolant on the tool and workpiece to prevent the loss of accuracy caused by tool wear and heat accumulation, and then collects the coolant, filters out the chips and recycles it. The lubrication is achieved through the centralized lubrication system to regularly guide the rails, lead screws and other moving parts of the oil supply.
