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The machining mechanics of the rotary ultrasonic drilling (RUD) is investigated based on the separation effect of ultrasonic vibration (SEUV), by quantifying the critical force at a certain ultrasonic vibration amplitude. Firstly, the SEUV principle is explored by establishing the kinematic trajectory of the tool. Then, the critical force of SEUV at certain ultrasonic vibration amplitude is modeled. The simulation shows that as the tool interference displacement caused by the axial force is larger than the ultrasonic vibration amplitude, the tool vibration is in a suppressed state and the SEUV effect cannot be achieved. Third, the principles of standard drilling and peck drilling are proposed. The essence of peck drilling in step motion shows advantage to assure SEUV of RUD. Last, the critical force of SEUV is measured in experiments and proves that the SEUV is suppressed as the force exceeds a certain value. The RUD verification experiment on SiC of standard drilling and peck drilling is conducted. It is found that when the cutting force exceeds the critical force in standard drilling, the SEUV is suppressed and there has no significant improvement on the drilling performance. In peck drilling, the cutting force is lower than the critical force periodically, where the SEUV is achieved and the ultrasonic vibration can make effective impacts on the material and improve drilling performance. [ABSTRACT FROM AUTHOR]

Localization is usually required for the near-net-shape billet before machining. In conventional research, the to-be-cut features only need to be transformed into the middle of billet to leave the to-be-cut material. However, if it is applied on the thin-walled feature, the machined feature would easily be beyond tolerance due to cutting deformation. Thus, conventional localization principle is not best for the thin-walled feature before the machining. To reduce reject rate for the near-net-shape billet, a new localization theory for the thin-walled features is investigated in this article. The workpiece's stiffness and cutting force distribution are considered in thin-walled feature localization. By the adjustment of the to-be-cut material, the cutting force is optimized to control the deformation of workpiece. Base on this principle, the cutting deformation is introduced into the constraint conditions of the localization optimization. Thus, the deviation of machined feature is prevented to be outside of tolerance as much as possible. In this work, a practical plate machining is rendered to verify this approach. It lays a theoretical foundation of thin-walled feature localization and is an effective solution for improving qualification rate of the near-net-shape part in industry. [ABSTRACT FROM AUTHOR]

Precision forging is a choice for compressor blade fabrication. Pressure and suction surfaces could be forged to yield design requirements but the blade edge could not. A localization for machining blade edge, considering forging deformation and surface continuity, is discussed in this paper. Different from making machining allowance more balance in past researches, minimizing the difference between machined surface and design surface is adopted. Except machining allowance constraint, new constraints about form tolerance and geometry continuity are built up for localization. As a model for generating tool path, the machining surface of the blade edge is determined by adjusting a group of section curves under proposed constraints. At last, a precision forging blade is applied to verify the proposed localization method. [ABSTRACT FROM AUTHOR]

Grinding is an important process to remove the material efficiently. Before the finish machining, it is necessary to remove the cusps by the wider grinding band for obtaining more uniform allowance. In this paper, the grinding wheel hold by the multi-axis machine tool is introduced into the free-form surface grinding. The engagement between the wheel and the to-be-ground surface is established for generating the paths. An instantaneous engagement model is proposed in terms of machine tool kinematic chain, and the spatial engagement is represented on a group of planes. Based on the engagement model, the grinding path generation for enlarging bands is transformed into an optimization. Different with traditional path generation, a slight local overcut is allowed on the wheel locations. However, the envelope of grinding engagements is limited in the required boundaries to satisfy the design tolerance. They are realized by adjusting the contact locations and orientations of the wheel. At last, a compressor blade is used to verify the advantages about the proposed path generation method. [ABSTRACT FROM AUTHOR]

To discover the knowledge from the machining process planning, it is important to obtain the geometric change of machining feature firstly. This paper proposed a methodology to acquire and describe the change process of machining feature. First, the concept of global machining datum is presented to construct the attributed adjacency graph for faces on the process model. The datum attribute of the vertex correspondent to the face is the unique identifier of correspondent face in the process model sequence. The datum attribute of the vertex, corresponding to the model face, is used to discern the correspondent faces in adjacent process model sequence. Second, the new faces, extinct faces, and maintained faces in adjacent procedure are classified by detecting the parameter changes. Third, with the help of the change types and interrelation of the faces, an algorithm is presented for geometric changes recognition of machining feature. As a result, the change process of a machining feature is discerned as a sequence of machining status. At last, the evolution of machining feature recognition method is verified with an example of machining process planning. [ABSTRACT FROM AUTHOR]