Energy saving technology of the hottest frequency

Energy saving technology of frequency conversion hydraulic plastic hollow molding machine

Abstract: Based on a brief introduction to the status of plastic hollow molding industry, this paper puts forward highly targeted solutions and schemes according to the characteristics of high energy consumption in this industry. The variable frequency speed regulation technology is introduced into the hydraulic transmission and control system, and a new generation of high-efficiency and energy-saving variable frequency hydraulic single/double position plastic hollow molding machine is developed and applied in practice

key words: energy saving, frequency conversion and speed regulation plastic hollow molding machine

1 introduction

in today's increasingly depleted world of energy, energy conservation has long been put in a prominent position by people. Compared with some energy rich countries in the world, China is an energy shortage country. However, our utilization rate of energy, especially the most important form of energy utilization, electricity, is very low, and there is a shocking waste. In the development of new products, new equipment and the transformation of existing equipment, we must pay attention to energy consumption as an important indicator. Plastic industry is a sunrise industry in the 21st century. However, its products are mainly produced by heating, pressurization and other physical methods, which determines the energy consumption characteristics of its production mode. For high-energy plastic products and equipment, how to save electricity has become an important means to enhance the competitiveness of products. Data shows that the commonly used plastic hollow molding machines in the industry include: PLC controlled pneumatic single/double station hollow molding machine and hydraulic single/double station hollow molding machine. Different types of machines are used according to different product raw materials; According to the grade and quality of products, special auxiliary equipment is equipped. For example, the main and auxiliary screw stranding system for blowing pearlescent surface and the "wall thickness controller" for automatically adjusting the wall thickness of embryo; An "in mold automatic labeling machine" for fusing the product trademark paper on the product surface at the same time during blow molding; It is used to check the pressure resistance and leakage test of products at the same time

technology from Germany and Japan shows that high-end plastic hollow molding machines all integrate the latest industrial control technologies. For example, the addition system of Color Masterbatch automatically prepared by microcomputer; The industrial computer system using configuration software, using the rich software resources and hardware system configuration of windows, develops a personalized man-machine interface, which integrates various parameters of the whole machine, such as temperature control parameters, extrusion speed parameters, embryo wall thickness adjustment parameters, pressure and speed of each step, and all parameters related to product quality and output into the system control, and calls and modifies them randomly. However, the price of this kind of machine, which represents the world's first-class standard, is also impressive, and the price is generally more than 300000 to 1million yuan. In the market economy environment, another standard to comprehensively measure the quality of a device is the performance price ratio, referred to as "cost performance". However, only high-quality, efficient and low-cost equipment can achieve high cost performance. Taking the plastic hollow molding machine of a German company with a price of 1.3 million yuan as an example, the defect of its high energy consumption operation has become the only reason why many customers who want to upgrade are deterred. In terms of domestic conditions, there are still a large number of low-grade models

in the market economy environment, especially the precision is ± 0.02%. In the Pearl River Delta region with developed market economy, the competition in the plastic industry is becoming increasingly fierce. It can be said that whoever has first-class equipment with high cost performance is likely to produce highly competitive and cost-effective products, which should be fastened in time; If the machine is not used for a long time after the experiment, the product. Whoever is likely to win the market. The invisible hand of the market, how to improve and improve the performance of the existing hollow molding machine, and how to achieve high quality, high efficiency and low consumption, is placed in front of us

2 frequency conversion hydraulic plastic hollow molding machine

based on more than ten years of production experience, the author has made an in-depth investigation and Research on the performance of various types of plastic hollow molding machines in practice, and thus targeted the local or complete transformation of various grades of hollow molding machines, and put forward the idea of frequency conversion hydraulic plastic hollow molding machine

2.1 working principle and characteristics of plastic hollow molding machine

according to different driving modes, plastic hollow molding machines can be divided into pneumatic and hydraulic types. No matter which method is adopted, the mold is sent to the glue receiving position, the glue embryo is received and then returned to the blowing position. MPa compressed air is introduced into the mold cavity through the blowing needle, and the glue embryo is blown into shape through the natural "blood relationship" between the upstream and downstream of the enterprise. The pneumatic single/double position plastic hollow molding machine controlled by PLC adopts full pneumatic drive, which has fast response and high efficiency. However, it is precisely because of the pneumatic mode, according to the public about Rong format f = P · s. Where f is the clamping force, P is the working air pressure of the system, and S is the effective area of the piston. Therefore, when the working pressure of the system is a certain value, the mode locking force is directly proportional to the effective area of the piston. Once the cylinder diameter is determined, the clamping force is also determined. Taking the cylinder diameter of 150mm as an example, under the working pressure of 6Mpa, only 10.38kn force can be generated. Therefore, this type of machine is only suitable for bottles less than 500ml. At the same time, it should be pointed out that due to the use of full pneumatic, the air consumption is indirectly increased. If the power consumption and maintenance cost of the air pump are converted, the unit consumption of the product is quite high

it can be seen from the above that if you want to produce containers with a capacity of more than 500ml, you can only use the clamping system of hydraulic cylinder. The hydraulic system can generate enough pressure to ensure the production and quality of various large volume products. But today's most advanced hydraulic servo system is still expensive. For example, the price of efrg-c-50 proportional pressure flow control valve adopted by Japan oil research company is about 7000 yuan, and the price of a servo cylinder with a stroke of only 14mm and a cylinder diameter of 120mm is more than 10000 yuan. Although the proportional pressure and flow control system is expensive, and the power consumption of the hydraulic system is about 30% of the power consumption of the whole machine, its excellent dynamic characteristics are enough to ensure the stability of product quality, so it is still widely used [1, 2]. According to the calculation, in addition to the external air supply system, the energy consumption of the whole machine. Taking the hydraulic double station machine with 70mm screw diameter of the extruder as an example, when producing 4500ml containers with PE (polyvinyl chloride) as raw material, the electric heating accounts for 22.6% of the power consumption of the whole machine, the motor of the extruder conveying system is 11kw, accounting for about 53%, and the hydraulic system is 7.5kW motor, accounting for about 24.4%. In the hydraulic single station machine, when producing 280ml PE material products, the power consumption of the hydraulic system accounts for 41.35% of the power consumption of the whole machine, the electric heating accounts for 42.33%, and the power consumption of the extruder feeding system (changed frequency drive) accounts for 16.32%. At present, the practice of most hollow molding machine manufacturers is to change the slip motor speed regulation to frequency conversion speed regulation only in the extruder conveying system

(to be continued)