Optimum Design Of Ultrasonic Horns And Research Of Experiments On Ultrasonic Machining Mechanism

Ultrasonic machining is an effective method for machining hard and brittle materials, such as glass, engineering ceramic, quartz and emerald. Rotary ultrasonic machining is a new processing method developed on the basis of traditional ultrasonic machining, the tool head plated (or sintering) with the CBN (or diamond) abrasive is rotated and vibrated simultaneously, which can combine the fine cutting properties of the CBN (or diamond) abrasive with the ultrasonic vibration of the tool. So, rotary ultrasonic machining has a higher efficiency and better surface quality than traditional ultrasonic machining, and its application range becomes wider and wider.Ultrasonic machining equipment mainly consists of ultrasonic generator. transducer and horn. The ultrasonic horn plays an important role on amplifing the amplitude of mechanical vibration. But the range of application of traditional horns is confined by many factors, the step horn's amplification ratio is larger but the shape factor is smaller (generally less than 1) and the cone horn's shape factor is larger but its amplification ratio is smaller, all of which limits the processing efficiency improving. And the traditional design method to solve the horn is complicated and has low adaptability. Therefore it is necessary to find a new design method to meet the design requirements of excellent performance horns.In this paper, from the viewpoint of improving the efficiency and quality of ultrasonic machining, a new ultrasonic horn with a larger amplification ratio and shape factor is worked out optimistically by using the large-scale finite element software ANSYS. On this basis, the theoretical and experimental studies of the traditional ultrasonic machining and rotary ultrasonic machining are carried out respectively .And the main contents are as follows:1. In the process of researching ultrasonic machining mechanism, the domestic and foreign research states of the tradition ultrasonic machining and RUM material removal mechanism were analyzed and generalized. And the two kinds of ultrasonic machining system and the working principle of equipment are introduced.2. Through applying large-scale general finite element analysis software ANSYS and taking the cubic spline as the axial section generatrix of ultrasonic horn, two-dimensional axial symmetry model is used to replace three-dimensional solid modeling, a new type of ultrasonic horn that not only meets the material allowable working stress conditions, but also has better shape factor and larger amplification ratio was design by using the method of optimum design on the base of the finite element dynamic analysis. Then the horn is validated, revised and tested by experiments. 3. According to the indentation experiment on engineering ceramics ,the impact and the formation of crack in ultrasonic machining are analyzed, the material removal rate models of hard and brittle materials of traditional ultrasonic machining and RUM were established respectively, then the main factors affecting the material removal rate of two processing ways are identified.4. The experimental study on traditional ultrasonic machining and RUM mechanism is conducted by using the new horn installed in the ultrasonic machining device. Through the experiments the law of influence on the material removal rate under different processing parameters (static pressure, abrasive particle size, tool head abrasives concentration, tool amplitude, tool rotation speed) in the two processing methods is obtained, and the optimal parameter combination is worked out by orthogonal experiments at two processing methods.