Speaker
Description
Deep-Hole drilling is applied for machining holes with a length-to-diameter ratio larger than ten. The applications are in the automotive, aerospace, and medical industries, and machine fabrication for the food industry. Different deep-hole drilling methods are available, ranging to diameters less than one millimeter. All methods are characterized by the high-quality hole and the high level of productivity archived. One example of a deep-hole drilling method is single-lip drilling, also known as gun drilling.
Single-lip drilling of deep holes is performed using high feed rates in a single pass. Therefore, chips must be removed by the metalworking fluid (mwf) pumped under high pressure through an internal cooling channel to the cutting head. In consequence, the mwf plays an essential role in the process reliability. However, chip jamming is a significant problem when chips wrap around the tool, leading to marks on the borehole wall and an increased drilling torque, causing sudden tool failure. Therefore, modeling the deep-hole drilling process is essential for improving the process. The removal of chips, in particular, is a challenge due to the dynamic chip position and the resulting constantly changing fluid-structure interfaces between the mwf and the chips.
Smoothed Particle Hydrodynamics (SPH) is applied to model the deep-hole drilling process, including the dynamic chip motions. Its Lagrangian and meshfree nature allows SPH to describe arbitrary moving surfaces and interfaces. Its application areas are especially when non-regular, moving free surfaces or dynamic fluid/structure interactions are present. The chips are modeled as rigid bodies using the Discrete Element Method or as flexible depending on the investigated problem, thus requiring coupled fluid-solid modeling.
The talk will briefly introduce SPH and the modeling of deep-hole drilling before problems of recent research are presented. Possible improvements to the process include, for example, improved chip removal by optimizing the drilling tool used [3] or reducing the amount of MWF required to ensure stable chip removal. Furthermore, it will outline how SPH modeling can be expanded to investigate the problematic chip jamming, which can result in drill breakage.
