Guidance principle of deep-hole cutting tools based on fluid wedge effect

Abstract

The existing guidance principle of deep-hole cutting tools has been used for more than 200 years. A novel guidance principle of deep-hole cutting tools is proposed based on the fluid wedge effect. The novel guidance principle stems from hydrodynamic lubrication in journal bearings and can prevent deep-hole cutting tool deviation during machining. A novel wedge-shaped body is fixed to the drill tip and the shank. The wedge-shaped body and the wall of the deep hole form four wedge-shaped spaces, and the cutting oil is drawn into the four wedge-shaped spaces to form four wedge-shaped oil films. Pressure develops in the oil film, and the forces of the oil films force the wedge-shaped body together with the drill tip and the shank to be centered in the deep hole and to move along the axis of the deep hole. The resultant force of the oil films tends to rectify the deviation of the cutting tool, and the resultant force equals 228 N in one example. Analysis and calculation of the forces of the wedge-shaped oil films were conducted, and the force of each oil film was 128 N in another example. Experiments showed that the average straightness of the deep holes machined by the novel deep-hole cutting tools was less than that achieved using the existing cutting tool. The parameters of the wedge-shaped body influenced the force of the oil film and the straightness of the deep holes.