Inserts
Deep Hole Drill Single Lip FE Model
Deep Hole Drill Single Lip FE Model
Deep hole drill single lip is a high-performance drilling process that allows to replace conventional turning and boring processes in production.deep hole drill single lip It enables to produce high-quality bores with good diameter tolerances and surface qualities as well as minimal runout, using a single tool. In addition, this machining method provides compressive residual stresses at the hole wall which prevent crack formation and improve component quality.
The FE simulation model for this process consists of the insert and the holder that holds the insert in the drill head. The tool is modeled as a rigid body with a constraint of its displacement and rotation limited only to the longitudinal axis (Figure 4). The movement of the workpiece is simulated by means of a separate constraint with angular velocity and speed limits. The insertion and withdrawal movements of the drill are modeled by applying a linear feed and cutting force.
When the drilling starts, the feed rate increases proportionally to the insertion speed. The feed force reaches its maximum value right after the contact point of the insert with the workpiece. After that, the feed force decreases and fluctuates around a lower mean value. This behavior is typical for the initial phases of the machining process.
In the following, a parametric study is conducted for the FE model of a deep-hole drill with a single-lip insert. The study focuses on the influence of the guide pad height, feed rate, and cutting speed on the thermo-mechanical response quantities (feed force, temperature in the drill head) and the residual stress at the bore wall.
For this purpose, the ABAQUS FE software is used. The software offers a feature for the calculation of the inelastic heat generation associated with plastic straining. This feature is activated in the simulation model with a value of 0.9. It is also necessary to define a density r of the material, which is set to 7850 kg/m3. The FE simulation model defines one solution-dependent state variable and another that controls the element deletion mechanism to represent material failure in the tool [18].
As can be seen from the Pareto chart shown in Figure 10b, the guide pad height has a very strong impact on the temperature in the drill head and a minor impact on the feed force. However, the impact on the residual stress is significant.
The results of the analysis of variance indicate that the standardized effects feed force, temperature in the drill head, and residual stress at the bore wall correlate well with the selected factors. This indicates the validity of the DoE approach in this case. The regression models that were obtained can be employed in the drilling process control in order to forecast resulting subsurface properties such as residual stress in advance. This can help to avoid a costly adjustment of the machining process in case the targeted subsurface properties are not achieved. The DoE approach is therefore a useful method to predict the required process parameters in order to achieve the desired result.
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