Selection of Fixtures for Turn-Mill Machining Lathe: Precise Matching of Machining Requirements

In milling and turning composite machining, fixtures are not only tools for fixing workpieces, but also key factors determining machining accuracy and efficiency. Faced with complex processing requirements, selecting a suitable fixture system requires comprehensive consideration of multiple factors such as material characteristics, process requirements, and production pace.

Rigidity is the primary principle for selecting fixtures. An excellent fixture system should have a stiffness of over 80% of the static stiffness of the machine tool. The rigidity of the fixture directly determines the vibration suppression ability during the machining process. For easily deformed workpieces such as aluminum alloy thin-walled parts, the combination of vacuum suction cups and imitation pads can achieve uniform force distribution. By controlling the pressure difference within 0.2 MPa through partitioned vacuum, it ensures firm clamping and avoids workpiece deformation.

Accuracy matching is equally crucial. The repeated positioning accuracy of the fixture needs to be one order of magnitude higher than the workpiece tolerance, which means that when machining workpieces with an accuracy of ± 0.01mm, the positioning accuracy of the fixture must reach ± 0.001mm. In the five axis linkage machining scenario, the zero positioning system combined with the torque motor turntable can perfectly achieve such precision requirements while eliminating errors caused by reverse clearance. Just like precision watches require precise gear matching, high-precision machining cannot do without high-precision positioning systems.

Process adaptability is another key consideration. The particularity of turning milling composite machining lies in the need to simultaneously cope with the centrifugal force of turning and the impact force of milling. Taking the machining of automotive turbine housings as an example, hydraulic cylinder clamps are responsible for stable clamping during turning of end faces, modular angular positioning blocks ensure precise indexing during milling of flow channels, and elastic deformation compensation fixtures solve the axial floating requirements during drilling and tapping.

The selection of fixtures is essentially the process of finding the optimal balance between rigidity, precision, efficiency, and cost. In this selection process, it is necessary to have a solid theoretical foundation, rich practical experience, and a keen sense of new technologies. Only by organically combining these aspects can we truly unleash the powerful processing potential of turning and milling composite machine tools.