Integration Processing Technology Of Micro-edm

As an applied micro machining technology, micro-EDM has brought many scholars around the world to pay attention on it, because of its non-macroscopic force, little machining unit and easy to be controlled during machining process. But with the development of minimizing and complication of the micro part, micro-EDM shows the shortcomings of low machining accuracy and fallibility. Therefore, this paper focuses on the integration machining technology of micro-EDM to improve the machining ability.In order to extend the potential of micro-EDM, this paper firstly studied the necessity and basis of the integration process of micro-EDM. Based on different characters of multi-plicate micro-EDM methods, a set of combination machining equipment had been proposed and developed. It mainly composed of a precise three-dimensional servo system, a micro pulse generator, a precise rotary spindle, a discharge grinding unit and a kerosene fluids circulation system, etc. The equipment can realize multi-machining function of micro-EDM including forming, drilling, milling, copying and wire cut, etc.As the accuracy is a key factor to the machining capacity, this paper studied the machining accuracy during the micro-EDM milling, micro-EDM copying and micro-wire-EDM process. In order to reduce the electrode erosion, the tube electrodes was substituted to the solid ones during the milling process. The tube electrode with thin wall structure and large out-diameter can realize both the high machining accuracy and efficiency.For the machining errors caused by the electrode erosion in micro-EDM copying, this paper proposed the machining strategy with rough and finishing phases. In rough machining, the negative tool electrode with long pulse duration is used to form the carbon layer on the electrode surface which can protect the electrode during the discharge. In finishing machining, the positive tool electrode with short pulse duration is used to obtain the better surface roughness and dimensional accuracy.For the machining errors caused by the wire tool deformation and deflection in micro-wire-EDM process, this paper proposed the mathematic model of machining gap. Based on the analytical solution of wire tool lateral vibration model in processing, the relationship between the machining parameters (open voltage, discharge capacitor, discharge resistor, servo reference voltage, worktable feeding speed, wire tension and work piece height, etc) and gap is set up at last. This paper also investigated the deformations of narrow beam produced by the micro-wire-EDM. The finite element method was used to simulate the machining process of narrow beam. With the simulation results, some means had been proposed to reduce this deformation.In order to improve the practical applications of micro combination EDM, this paper had studied the technique of combination process. Firstly, according to the characters of structures and micro-EDM process, the micro structures were classified to holes, shafts, side wall structure, complicated 3D structure and array structure, etc. And then, different machining methods were arranged for these different structures, and the standard process of machining route was also set for the micro combination EDM. The process includes machining plan designing, screening, simplifying and breaking, etc. At last, the location errors were studied in the micro combination EDM, and some means had been proposed to improve the machining accuracy.In order to verify the micro combination EDM technology and the equipment proposed in this paper, a micro planetary gear reducer with the 1.8mm out-diameter was designed and manufactured using the combination method. The reducer has five micro components including a sun wheel, a planet carrier, three congruent planet wheels, an annular gear and a cover. Based on the structure characters of each component of reducer, micro-EDM drilling, micro-wire-EDM, micro-EDM layer milling and micro-EDM copying were integrated used to make the micro components with high accuracy successfully. The machining dimensional accuracy, surface roughness and cost time were analyzed in this paper at last.