CNC lathe machining is a high-precision and high-efficiency machining method that uses digital information to control the displacement of parts and cutters by automatic machine tools. It is an effective way to solve the problems of aerospace products and parts with many varieties, small batches, complex shapes, and high precision, and to realize efficient automatic machining. Next, let’s take a look at the composition and working steps of CNC machine tools.
1. The composition of CNC machine tools. The CNC machine tool is composed of a program, an input and output device, a CNC unit, a servo system, a position feedback system and the machine tool body, which are briefly introduced below.
- 1. Numerical control unit. The CNC unit is the core of the CNC machine tool and consists of three parts: information input, advance cnc machining and output.
- The numerical control unit receives the digitized information, and after decoding, interpolation and logical machining by the control software and logic circuit of the numerical control device, it outputs various instruction information to the servo system, and the servo system drives the executive parts for feed motion. Others include the speed change, reversing and start and stop signals of the main moving parts; the tool command signals for selecting and changing tools, the start and stop of cooling and lubrication, the loosening and clamping of workpieces and mechanical parts, the indexing of the indexing table and others Auxiliary command signal, etc.
- 2. Servo system. It is composed of a driver and a drive motor, which together with the execution parts and mechanical transmission parts on the machine tool form the feed system of the CNC machine tool. Its function is to convert the pulse signal of the numerical control device into the movement of the machine tool moving parts. For a stepper motor, each pulse signal will make the motor rotate an angle, and then drive the moving parts of the machine tool to move a short distance. Each execution part of the feed motion has a corresponding servo drive system, and the performance of the entire machine tool mainly depends on the servo system.
- 3. Position feedback system. Servo motor angular displacement feedback and CNC machine tool actuator (table) displacement feedback. Including gratings, rotary encoders, laser rangefinders, magnetic gratings, etc. The feedback device converts the detection result into an electrical signal and feeds it back to the numerical control device. Through the comparison, the deviation between the actual position and the command position is calculated, and the deviation command is sent to control the feed motion of the executing part.
- 4. Machine tool mechanical part. For the CNC machine tools of the advance cnc machining center, there are also parts such as a tool magazine for storing tools and a manipulator for changing tools. The composition of the mechanical parts of a CNC machine tool is similar to that of an ordinary machine tool, but the transmission structure is simpler, and the accuracy, rigidity, and seismic requirements are higher. Its transmission and speed change system are more convenient for automatic expansion.
2. The working steps of CNC machine tools. The following steps should be passed through the CNC lathe machining:
- 1. Preparation stage. According to the drawings of the processed parts, determine the relevant machining data (tool path coordinate points, machining cutting parameters, tool size information, etc.). And select other auxiliary information according to the process plan, selected fixture and tool type.
- 2. Programming stage. According to the advance cnc machining technology information, compile the CNC machining program (machining technology description) in a language that can be recognized by the CNC system of the machine tool, and fill in the program sheet.
- 3. Prepare information carrier. According to the compiled program list, the program is stored in an information carrier (punch tape, tape, disk, etc.). All machining information is transmitted to the CNC system through the information carrier. If the CNC machine tool is connected to the computer, the information can be directly loaded into the CNC system.
- 4. Machining stage. When the CNC system of the machine tool executes the program, it decodes and calculates the machining program statements, converts them into action instructions, and drives the moving parts. Under the unified coordination of the system, the moving parts are driven to move in time, and the workpiece is automatically processed.