Research On Ultrasonic Elliptical Vibration Cutting Theory And Design Of It's Device

With the rapid development of China's machinery industry,people's requirements on machine components become more and more rigid. The requirement is not only rigid machining dimensional accuracy, flatness, roundness and other high precision shape and position on many parts, but also smaller residual stress of machined surface of requesting parts is needed, which can maintain the accuracy of parts for a long time. For such parts, if we adopt the conventional machining techniques which rely solely on increasing the sharpness of cutting tools and reducing the feed volume and so on, it cannot greatly reduce the cutting force in process and it is difficult to achieve the desired processing results due to the constraints of conventional cutting characteristics. Ultrasonic vibration cutting is a processing technology, in which high-frequency ultrasonic vibration force is regularly added to the tool, so that the cutting tool can periodically cut and separate from the work piece. Compared with the traditional cutting techniques, Ultrasonic vibration cutting can effectively reduce the cutting forces, the cutting temperature and improve processing quality. However some limitations still exist. For example, when the tool leaves workpiece, there are the friction and impact between the rake face of the tool and the machined surface, which seriously affects the machining accuracy of the machined surface, while the cutting tool will bear an ever-changing alternating stress with the ultrasonic vibration in the cutting process. These limitations restrict further applications of the ultrasonic vibration cutting technology in the field of precision machining.Ultrasonic elliptical vibration cutting technology makes the ultrasonic elliptical vibration add to the cutting tool, where the cutting edge moves up along the elliptical path, thus achieving intermittent vibration cutting at high-frequency. When the tool left the surface, the rake face of the tool will not contact with the machined surface, which makes the friction avoided. Meanwhile, the harmful friction between the rake face of the tool and the chip becomes favorable cutting force and the shear angle of cutting increases, which in turn makes cutting force reduce significantly. In this case, the workpeice can get higher machining accuracy, smaller chip and long tool life and lower surface roughness value, etc.In this paper, the principle of ultrasonic elliptical vibration cutting and the situation of loading are explained and ultrasonic elliptical vibration system is designed. Based on the modal and dynamic analysis of the finite element method, the various parameters of the model were modified to meet the needs of the vibration modality and the inherent frequency. The mathematical model of elliptical of ultrasonic elliptical vibration cutting mechanisms is established and the variation path of the elliptical cutting tool is simulated with MATLAB. The main contents are as follows:1. The principle of elliptical vibration cutting are explained, and the research status of domestic and international ultrasonic elliptical vibration cutting are summarized. By analyzing the principle of ultrasonic elliptical vibration cutting and the force of ultrasonic elliptical vibration cutting region, a number of advantages comparing to the conventional ultrasonic machining are obtained.2. Ultrasonic elliptical vibration cutting system are designed. An ultrasonic elliptical vibration structure with two perpendicular incentives is presented through analyzing the model of the longitudinal vibration horn. By the design theory of horn, a conical horn and a composite horn are designed respectively, and each horn is analyzed based on the finite element method.3. The mathematical model of ultrasonic elliptical vibration cutting mechanisms is established. To study the trajectory of tool edge, the ultrasonic elliptical vibration cutting mechanisms is simplified to a simple rod-like structure. Based on mathematical formulas, this mechanism is proved able to generate elliptical vibration. At last, the variation path of the elliptical cutting tool is simulated with MATLAB. Based on the modal and dynamic analysis of the finite element method, the various model parameters are obtained.4. The ultrasonic elliptical vibration cutting horn is produced, and the cutting device of ultrasonic elliptical vibration is designed and manufactured. The ultrasonic elliptical vibration system is assembled and tested. The results show that elliptical vibration can be achieved.5. The entire ultrasonic elliptical vibration cutting machine is mounteded on the turning lathe; and the lathe and Elliptical vibration system are mounted to meet the requirements of precision machining. In addition, the parameters of ultrasonic elliptical vibration cutting are theoretically analyzed and presented.