Core tip: injection molding is one of the main methods of Thermoplastics into various products, compared with other plastic molding method, injection molding method has complicated structure and precise size of plastic, strong adaptability, short molding cycle, high production efficiency and easy to realize the advantages of automation etc..
Injection molding is one of the main methods of Thermoplastics into various products, compared with other plastic molding method, injection molding method has complicated structure and precise size of plastic, strong adaptability, short molding cycle, high production efficiency and easy to realize the advantages of automation. In the world, injection accounted for about 30% of the total plastic molding and injection molding machine, the annual production of (units) is about more than plastic processing machinery of the total annual output of 50%. Hydraulic system is an important part of the injection molding machine, injection molding machine at home and abroad at present most using hydraulic system to complete the plastic mold injection mold, injection molding, packing and T order, so the demand for electricity, energy consumption has become the main form in the production of injection molding. In recent years, the energy saving renovation of some small and medium-sized production enterprises in Pearl River Delta region using frequency converter technology for hydraulic system of injection molding machine, greatly reduce the energy consumption in the production of injection molding, thereby reducing the cost of production of injection molding products obviously, bring considerable economic benefits to the enterprise.
1, injection molding machine working characteristics
The injection molding process of injection molding machine 1.1, the work cycle is a start from the mold closing action cyclical process in the cyclical process of hydraulic system must complete a series of actions: mold, mold, injection, holding pressure and overall mobile seat ejection products etc.. The working cycle of the injection molding machine is shown.
The main working parameters, working parameters of 1.2 injection molding machine in a working cycle of hydraulic system and has a close relation with the injection pressure, injection rate, clamping force, pressure etc.. Injection pressure is the important factor to overcome the flow resistance of molten material flowing through the nozzle, runner and mold cavity, ensure the stability of mold filling and ensure the accuracy and qualified rate of injection products. When the screw diameter is constant, the injection pressure is determined by the hydraulic system. Injection rate is a parameter to characterize the melt filled mold cavity, which directly affects the quality and productivity of the product, and the size of the product is controlled by the oil flow rate of the injection cylinder. The clamping force is maximum clamping force of the clamping mechanism for injection molding machine of mould can be applied, and it has become the nominal injection volume parameters of injection molding machine specifications, for hydraulic toggle clamping device, the clamping force is determined by hydraulic system and hydraulic toggle mechanism; the clamping device, locking force size is determined by the hydraulic system of injection molding machine.
Holding pressure is one of the important parameters of the injection molding process. The ion of the holding pressure and the holding time directly influences the quality of the injection products.
2, the hydraulic system of injection molding machine hydraulic system is an important part of the injection molding machine, it must meet the various stages of the whole work cycle required the different requirements of the pressure and speed. Hydraulic system should have the characteristics of good stability, high precision and high sensitivity, low noise, energy saving and so on. The hydraulic system is mainly composed of the hydraulic pressure, the valve, the oil cylinder and the circuit.
In the injection molding production, according to the needs of the injection molding process, the injection molding machine hydraulic system work flow and working pressure should be constantly changing, so the power consumption of hydraulic system of injection molding machine should also be changing with the work flow and work pressure. Schematic diagram for the hydraulic system of a working cycle of domestic XS-ZY -500 injection molding machine in the work flow of the hydraulic oil cylinder to change change, schematic diagram of the power consumed and working flow of the hydraulic chestnut by (2) of the table: therefore, the work flow of the hydraulic pump can be expressed as (3 type: (3) by type) visible, when the value is constant, the work flow of the hydraulic pump and the drive motor frequency is linear, which can make the flow changes smoothly, to achieve stepless speed regulation.

3.2 system components for the use of frequency converter to adjust the hydraulic pump flow of injection molding machine working flow diagram. The signal acquisition device (sensor) work flow in different stages of injection molding machine injection molding process for hydraulic oil is collected and transmitted by the constant flow of current value in the form of PLC (programmable logic controller), and by the output flow detection for hydraulic oil pump actual output flow detection, the detection the signal from the current / voltage converter converts the voltage value transmitted to PLC, PLC compared to the actual flow and flux. According to the results of PLC, the output of the driving motor is given to numerical transmission to the inverter, by adjusting inverter drive motor / pump speed, so as to adjust the output flow of hydraulic pump, which can meet the different stages of flow injection cycle?

Flow regulation of hydraulic system of injection molding machine by frequency converter.
3, the characteristics and ion for inverter inverter drive motor speed requirements has the following characteristics: in a small slip operation, low loss, high power factor; the wide range of speed, frequency from a few Hz to several hundred Hertz, speed and high precision, precision of 0.5%~1%; the automatic smooth acceleration and deceleration; the energy-saving effect is very obvious, generally more than 30%; the complete protection, maintenance of a very small amount of T..
The inverter according to the actual condition of T. injection molding machine and ABS market instability since the second quarter of this year, although ABS prices ped significantly, but the market turnover is still limited, the characteristics of some small dealers began to have doubts about the market outlook, produce psychological inventory as soon as possible, is not conducive to market stability.
Industry believes that the ABS market downturn, one is reflected in the previous price.
Rise too fast, too fast, it is difficult to adapt to the market; two is a reflection of the R tour companies cannot afford to buy high priced, force decreased significantly, suppliers have to price: according to the industry reflect, many dealers attitude are changing, early enough confidence, but worried that the market outlook will decline, so often to the shipment. But some of the large, international market price is still in a rising trend, the foreign price has been $930950 /U imports cost of tea, inevitable demand to supply to the sales price of tea. Therefore, the recent overall price level may rise. There are also experts believe, ABS market outlook, not necessarily rise, because although the international market price was on the rise, but the domestic businesses are basically not recognized by rising prices, end users do not accept, so the market will continue to maintain high prices is still hard to say that the 1 pen, the downstream enterprises, home appliances. K production is not it is ideal, allow part of the appliance product inventory more, will affect the demand for ABS. Once ABS prices are not. Rise too fast, it will in turn inhibit its digestion, which led to its decline in prices.