The Study Of Key Questions On Automatic Balance In Turning And Broaching Process Of Crankshaft

The crankshaft is one of the most important parts in the engine. So not only dimension and weight of engine, but also dependability and life of the engine are affected greatly by its structural parameter and processing technological level. The crankshaft accident is likely to cause the serious destruction or ruin of the other parts of engine. So, To increase and to improve the manufacturing process of the crankshaft is an urgent requirement to develop the engine manufacturing constantly. Turn-Broaching Machine Tool will be used more and more because of its great efficiency and high quality in the course of manufacturing pin bearing.Base on the domestic CNC Turn-Broaching Machine Tool at present, the dynamics balance isn't solved excellently as a result of the malpractice of low velocity and sleazy surface, some key questions on the special purpose fixture with on-line automatic balancing function for the crankshaft manufacturing process is researched . In the paper, these problems are taken into carefully studied that the on-line automatic dynamic balancing equipment and Balance head design, automatic banlance head power supply method, selection of sensorsthe the calculation for Amplitude and phase of imbalance and so on. The following recapitulations are the main achievements.1. According to the constitute, structural characteristic, manufacturing techniques and development of crankshaft, the localization and clamp projects that crankshaft is fixed in the machine tool are designed. According to the projects , automatic balance equipment, balance head are design and automatic banlance head power supply method is studied.2. In the paper, the chief difficulties and critical technique of rotating machinery auto-balancing are discussed in detail and two corresponding projects are adopted following as the initial balance and on-line automatic balance . The initial balance is a balancing way before processing crankshaft. The position of balance weight is adjusted once artificially for the same model crankshaft. That process is measuring the vibration signal of machine tool axis series (including fixture and workpiece) in low rotate speed and calculating unbalance weight according to the theory of dynamic balance and then adding balance weight to the fixtures at two tops of the crankshaft. On-line automatic dynamic balance is controlled by computer. It can dynamically control the process of machine tool manufacture so as to solve the new unbalance for non-standard form crankshaft. In the paper, the construction on initial balance and on-line automatic balance of the crankshaft fixture is designed.3. In the paper, the sampling and digital signal processing on the vibration are discussed. On the base of influencingcoefficient method,the system is demarcated on the adding weight,then the relations of phase-amplitude and imbalance quality are calculated.The content of the article has important practical value for improving manufacturing quality of CNC Turn- Broaching Machine.