Системы управления электроприводами прямоточных волочильных станов: анализ достоинств и недостатков

Abstract

The analysis of the control systems for straight-through drawing machine with different power supply circuits of the drive motors has been made. It is shown that the main task of the feasibility of the process of drawing – equality-second volume of metal passing per unit of time at each section of the drawing machine is solved either by means of mechanization or via an electric drive and automation tools. The matter has been settled through mechanization at sliding and magazine-type machines. In them, with installation of the simplest systems of unregulated electric drive, the problem is solved in the first case through wire slip on drawing capstans, in the second case – the use of special driver devices. However, such wire drawing machines have significant drawbacks: higher energy costs, low productivity. At straight-through drawing machines the process reliability question has been solved by an automated electric drive. Wire at such machines from the capstan is directed into a die and then to the next capstan without slipping on the capstan or additional bends and twists. In practice for drawing machine’s electric driving, systems with series, parallel and individual drive motor power supply are used. The analysis of schemes with a serial connection of motor armatures revealed possibility of providing self-drawing process, namely invariance countertension speed drawing. But we have found that the deviation countertension substantially influenced the change in resistance and wire deformation conditions in the portage , and due to the different mechanical inertia blocks — acceleration and deceleration of the machine. The errors in the regulation countertension reach unacceptable according to the technological requirements of units. In the case of circuits with parallel motor armature self-drawing process is absent and no specially organized every countertension management systems essentially depends on the motor voltage. Studies of various design options of electric control systems (indirect regulation, countertension sensors, pressure of metal on a die and tension) showed that the best performance can be achieved in the application of automatic control systems, acting as a compensation system abnormalities, leading to breakage of the wire. However, experimental studies have shown that the error in the regulation countertension in any system with parallel connection of the motor armature is also greater than the maximum allowed. Undoubtedly, higher quality indicators drawing process control is achieved with the use of electric drive systems with individual power motors. In such systems, a given drawing speed accuracy and the amount of force countertension provided with closed automated electric control systems. Errors in the regulation of technological origin does not exceed the maximum allowable values, while drawing speed is 5 times or more higher than the maximum achievable on machines with other power supply circuits of motors.