The five-axis machining center is a high efficiency of high precision CNC machine tool. Through the linkage control of five coordinate axes (X, Y, Z and two rotating axes A / B / C), the processing of complex surface and special-shaped parts is realized. Its core lies in multi-axis cooperative motion and flexible adjustment of tool posture, the following are detailed analysis and matters needing attention:
1. The working principle of the five-axis machining center
1. Motor structure
-Linear axis (X / Y / Z): controls the linear movement of the tool or bench.
-Rotary axis (A / B / C): usually combined in the following form:
-Double turntable (A + C or B + C): workpiece rotating, suitable for small parts.
-Table + swing head (such as axis B rotation + axis A rotation table): the tool and workpiece can be rotated, suitable for large parts.
-Double swing head (A + B): the tool is multi-angle tilt, the workpiece is fixed.
2. Coordinate transformation and linkage control
-Calculate the tool path in real time (CAM software generated by the CNC system), synchronize the linear motion of the tool with the angle change of the rotation axis, and ensure that the cutting point is always perpendicular to the surface (avoid interference).
-Typical algorithm: the inverse kinematics solution to convert the position of the tool in the workpiece coordinate system into the actual displacement of each axis.
3. Tool center point control (TCP)
--Some high-end systems support the TCP function, which means that the tool tip position is fixed and the rotation axis does not require reprogramming when adjusting the attitude.
2. The key problems and matters needing attention in the processing
1. Interference and collision risk
-Cause: Rotary shaft movement may cause a tool, handle, workpiece, or fixture collision.
-the way to deal with a situation:
-The collision detection function using the CAM software (such as the Vericut).
-Limit the travel of the rotation axis (e. g. A axis to avoid the ± 90° limit position).
-Simulate the machining path and check the tool extension length to interfere with the fixture.
2. Workpiece clamping and coordinate system setting
-Ensure that the workpiece is stable during rotation to avoid displacement due to centrifugal force.
-The coordinate system origin is usually located at the intersection of the axis of rotation (reducing the computational complexity), otherwise the dynamic offset compensation is required.
3. Cut parameters optimization
-Grose rate: reduce the feed speed (avoid centrifugal vibration).
-Tool selection: short blade tool has better rigidity and less suspension; ball blade is suitable for surface finishing.
-Cutting force control: the tool contact area changes during side milling, requiring adaptive adjustment of the cutting depth.
4. Precision and error compensation
-Reverse clearance of rotation axis: compensated by grating ruler or system parameters.
--Thermal deformation: monitor the spindle and rail temperature or adopt cooling system.
-Tool wear: the wear in multiaxial machining is more likely to affect the contour accuracy, requiring regular detection.
5. Programming complexity
Avoid direct manual programming and rely on CAM software to generate blades (such as PowerMill, Hypermill).
Note the singularity problems (such as universal joint lock), and optimize the tool path to avoid rapid axis turnover.
6. Processing strategy selection
Positioning processing (3 + 2 axis): fixed rotation axis separation processing, suitable for polyhedral parts.
Continuous five-axis machining: curved surface high-speed cutting, the need to ensure the dynamic performance of the machine tool.
3. Typical application scenarios
Aerospace: impeller, engine blades (need to avoid tool vibration).
Medical device: Artificial joint (high surface finish requirements).
Mold manufacturing: deep cavity mold (inclined tool to avoid the side wall).
4. Maintenance and calibration
Check the rotating shaft bearing wear regularly (affecting the rotary accuracy).
Calibrate the five-axis linkage accuracy using a laser interferometer or club instrument.
Through reasonable planning process and rigorous simulation verification, the five-axis machining center can significantly improve the machining efficiency and quality of complex parts, but the technicaltechnicallevel and experience of operators are high.