Analysis and application of deep hole drilling straightness error influenced by cutting fluid

The equation for deep hole straightness error is established by using the cutting fluid Reynolds equation, bar bending deformation theory and drill bar angle equation, which reveals relationships between cutting fluid inlet pressure, drill rotation, whirl, squeezing feed and deep hole straightness. In the condition of cutting stability, deep hole straightness can be improved by reducing the cutting fluid inlet pressure, increasing the drill rotation speed or decreasing drill whirl speed and extrusion speed. A new type of multi-injection device is designed that can effectively reduce the deep hole straightness error through an additional shunt cavity and injection series to reduce the inlet pressure. Squeeze film dampers (SFD) are designed, and extruding whirl and extrusion of the deep hole drill pipe are decreased by using oil film resistance, which improves the deep hole straightness. Testing deep hole straightness error under the action of the multi-stage injection device and SFD, and drill in the lower cutting fluid inlet pressure and small whirl and extrusion have a better deep hole drilling straightness is verified. New ideas and a design scheme are given to control the deep hole processing straightness error. ©, 2015, Nanjing University of Aeronautics an Astronautics. All right reserved.