Research On The Control Technology Of Weld Line

One of the problems in the plastic processing that have not been solved is the weld line,which is also the primary reason why the current plastic product rejection rate is high and the business economic benefit suffers injury seriously . It is created, when the front part of the molten resin which comes from different directions by cooling meet each other. Weld marks in products will weaken the structural strength, produce surface defects, produce the chromatic aberration in electroplating processes, and make serious damage to the mechanical properties of products. In recent years, the research on how to eliminate the injection molding product fusion mark obtains the universal attention.This subject combines research of removing fusion line which is a project from natural science foundation of Ningbo, according to the produce practice of double-barrel of washing machine from NiGuang group of Ningbo. After having consulted much domestic and international material about injection molding, this dissertation introduces the injection molding's development, the development trend in our country and foreign countries and the eliminating of fusion line at the present time. The dissertation still points out the mark of welding produces mechanism, and points out eliminating fusion line with sequential valve gating control. In this dissertation, the formation of the weld marks was studied.The flow of injection molding is a very complex physical process. The Non-Newtonian melted plastic in the high-temperature pressure-driven flows through that gate to lower the temperature of the shaped cavity. On the one hand the melted plastic transfer as a result of mold heat, and rapid cooling; on the other hand, the heat generated by high-speed shear and at the same time Melt solidification accompanied by volume contraction, molecular orientation and crystallization process possible. This article has studied the injection molding numerical simulation theory, given the plastic viscoelasticity and the viscosity model and the backfill process mathematical model as well as the model value solution method. This article has Studied the principle of controlling weld marks with the order pouring, given the interval formula of opening a gate, given the number and location of the gate of the mathematical model of optimization and genetic algorithm for solving the problem; Then, the fusion mark control optimization model was given, to which the steepest descent law was used to carry on the solution and obtained a group of various runners timing control superior melt. This article mainly elaborates various runners opening timing control, using the genetic algorithm establishment fusion mark's timing control model, corresponds through the adjustment to the runner opening time, may move the Welding Lines to the position which we hoped.To achieve the goal sequential controlling multi-runner, it Requests the nozzle needle valve to open and close depending on the filling process. The melt through the nozzle can be used as a mobile front, and then open the nozzle on the edge of the outflow of hot material flow more directly into the nozzle by the middle of the previous internal melt outflow. That is, there is only one flow front in a filling direction, thus eliminating the branch meets the forefront of mobile multi-issue, so that weld marks or disappear off to the sides is not important.In this paper, Pro/E software was used to establish a double-barrel laundry model. Inducts the establishment model to the mold analysis software Moldex3D, to designed the product using the control optimization algorithm's result double to wash clothes the including drums to carry on the control optimization simulation testing. From the simulation's results, we can see that the sequence control system is basically to achieve effective control of weld marks. The quality of products has been greatly improved.Finally, I designed a sequential control system. The main function of the sequence control system is: 1) the realization of the hydraulic pump station to load and shutdown control of electrical and mechanical protection; 2) the realization of the system power distribution; 3) the realization of computer-controlled hydraulic valve driver;4) To eliminate weld marks and improve the quality of finished products, issue instructions timely to hydraulic valves in accordance with the procedures, Control multi-gate's open or close. There mainly is four parts in this Control system: the power system, control system, control valves and control system interfaces with the injection molding machine. The basic control unit PLC was used in the control system. That is because the PLC process signal time is short and all I / O input and output signals are used photoelectric isolation. The outside circuit of industrial site and the internal electrical controller are isolated between circuits. Shielding measures are used in the modules. Once the power supply or other hardware and software anomalies occurred, CPU take immediate and effective measures to prevent the failure from expanding. The high quality is at low price; the performance-to-price ratio is high; the installment is simple, the service is convenient.