| Free forging is a basic process of metal forming. Free forging process is currently carried out on the hammers and the hydraulic presses. The press processes are in low precision and the forge pieces are in low uniformity, large allowance and tolerance, which result in the waste of subsequent cutting machining. With the development of the new technology of switched reluctance servo motor(SRSM), the screw presses driven by SRSM have realized the function of numerical control(NC) that leads to the development opportunity of free forging on screw presses.In this paper, the control technology of the robot and the free forging on the servo screw press was studied. The main research contents are as follows:(1) The best types of the servo screw press applied in free forging were analyzed. With the highest efficiency as the objective function, the mathematical model of the optimization of the model of the servo screw presses was established. The transmission structure and the stiffness of various servo screw presses were analyzed. The relationship of striking efficiency and whole stiffness of the servo screw presses were revealed. The whole stiffness of the screw presses with direct drive and spline direct drive were analyzed. The optimal structure of the screw presses was revealed. The mechanism of the high efficiency of the direct drive screw press was expounded.(2) The NC forming method of free forging on servo direct drive screw presses was put forward. With the application of the NC technology of the high main movement speed of the direct drive screw press and by introducing the concept of equivalent stiffness, the relationship between the striking energy and the striking force was clarified. Through the real-time monitoring of tonnage instrument, the NC of different speed, energy and force were realized. The different parameters of workpieces by free forging were simulated by DEFORM software. The process parameters were analyzed. The optimal parameters of cylinder Φ38mm for upsetting process of free forging were obtained.(3) Research on the coordinated control of the robot and the free forging on servo direct drive screw press. The 3D prototype of the servo screw press and the robot were built by using SolidWorks. The trajectory of the feed motion of the robot was planned. The running states of displacement and velocity of the robot’s clamping end were determined by ADAMS, the optimal trajectory of the motion of the two machines were determined by optimizing the objective function with the shortest cycle time of continuous work. With the highest efficiency, it was ensured that the synthetic motion between the main movement of screw press and feed movement of robot didn’t interfere.(4) The free forging experiments were carried out by the high efficient servo direct drive screw press, adopted the optimal process parameters. The effectiveness of the simulation and the advantages of the parameters of three stages are verified. The data of the repeat precision of the strike force and the uniformity of different size of forge pieces were analyzed. The error of the actual striking force and the simulation result was less than 10%.The results of the study in this paper showed that: the free forging process of upsetting cylinder Φ38mm on the direct drive servo screw press, reached the targets that the striking efficiency of 0.8398, the repeated error less than 2% of striking force, the size deviation less than 0.2mm of forge pieces. The results of this paper has a guiding effect in the change of free forging process. |
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