Follow-up grinding technology, also known as tangent-tracking grinding or follow-up grinding, works on the core principle of high-speed, high-precision synchronous linkage of multiple motion axes of the machine tool (mainly the workpiece's rotation axis C-axis and the grinding wheel's feed axis Z-axis) through precise control of the CNC system. During the machining process, the grinding wheel remains tangential to the workpiece's surface and performs real-time tracking grinding along the workpiece's contour.

Specific Workflow: Taking the machining of a triple eccentric butterfly valve as an example, the workflow is as follows:

1. Workpiece Positioning

Secure the workpiece to the machine chuck.

Eccentricity Angle (Tooling Installation Angle): Note that the tooling installation angle is the same as the eccentricity angle, and they must be consistent.

2. Multi-Axis Linkage

After grinding begins: C-axis: The headstock drives the workpiece to rotate around its spindle axis. Z-axis: The grinding wheel head performs precise lateral feed movement according to the workpiece's rotation angle.

3. Real-Time Tracking: The control system calculates and controls the motion trajectories of the C-axis and Z-axis in real time based on a preset mathematical model and machining program. As the workpiece rotates, the grinding wheel moves up and down synchronously, ensuring that its outer cylindrical surface remains tangent to the workpiece surface.

4. Grinding Completion: During one revolution of the workpiece, the point of tangency between the grinding wheel and the workpiece also moves up and down one revolution, thus completely grinding the desired non-circular contour.

The key to this technology lies in the dynamic synchronization accuracy between the C-axis and Z-axis, requiring the servo drive system to have extremely high responsiveness and control precision to ensure micron-level machining accuracy even at high speeds.

The principle of follow-up turning is the same as that of follow-up grinding, except that the spindle (workpiece) rotates at a faster speed during turning, and the Z-axis moves at a faster speed as well. This makes the coordination between the two axes more difficult to control. The Z-axis must quickly reach the designated position and stop quickly, and then quickly change the direction of movement while accelerating. Follow-up cutting places higher demands on the mechanical and electrical coordination of the machine tool than follow-up grinding. Only with a very good coordination can follow-up cutting be successfully completed.
Meanwhile, we jointly developed a convenient tool-tip following operation method with Siemens, which simplifies the parameter input and program calling process. The layout is reasonable and the operation is easy to understand. You only need to input the values from the drawing into the corresponding parameters to generate the machining program, which effectively lowers the operating threshold and makes CNC machining more time-saving and efficient.