In the plastics processing industry, whether it is extrusion, injection molding, calendering, hollow molding, or film blowing, spinning, etc., in addition to the host that meets the requirements, the mixer often needs a large number of auxiliary equipment to jointly complete each Item processing operations. The perfection, automation and rationalization of auxiliary equipment for plastic processing determines the quality of products and the viability of enterprises to a certain extent.
According to their functions, plastic auxiliary machines include three types of equipment for feeding systems, temperature control systems, and pulverizing equipment for scrap recycling. They play different roles in the plastic processing process.
Feeding system provides high-quality raw materials
The auxiliary processing equipment for the feeding system mainly includes drying, conveying, metering, and mixing equipment.
Drying equipment is used for material pretreatment before the molding process of moisture-absorbing materials, such as ABS, polyoxymethylene (POM), polycarbonate (PC), nylon (PA), organic glass (PMMA), etc. In certain processing processes of polyolefin plastics, in order to ensure the quality of the products, they must be highly dried, such as in the production of random copolymer polypropylene PP-R pipes, injection molding of pipe fittings and polyethylene raw materials for cross-linked polyethylene It is also necessary to dry the material to the required moisture content.
In the production and processing, according to the product's requirements for the moisture content of the raw materials, different drying methods and drying equipment must be used. For fillers and PVC and other pellets, oven dryers are often used; for heat-sensitive plastics, rotary double-cone vacuum dryers are used; for continuous drying, direct hopper dryers are often used.
For the feeding system, the powder conveying adopts a spring tube conveying system and a Roots blower-type air conveying system, while the particle conveying and feeding uses a vacuum feeder. Most domestically produced vacuum feeders adopt single-phase or three-phase motor separation feeding systems, with a conveying capacity of 100-400kg/h. At present, such domestically-made equipment is comparable in function to foreign equipment, and many products are also exported overseas.
Centralized feeding equipment is mostly suitable for large-scale and automated production processes. The equipment adopts computer centralized control, and various raw materials are weighed in proportion through the metering device and then enter the mixer. The hopper is equipped with a material level sensor, which can automatically open or close the storage barrel on the conveying pipeline according to the amount of material. The key technology of the centralized feeding system is the accurate measurement of the electronic scale, which can accurately feed the required materials in proportion. my country's centralized compounding system has solved the difficulty of accurate measurement by adopting foreign technology and accessories.
Plastic mixer mainly refers to high-speed mixer and low-speed cooling mixer. High-speed mixers are generally divided into single-speed and double-speed mixing. The low speed of the two-speed mixing is 450 rpm and the high speed is 950 rpm; the cooling mixer speed is generally 133 rpm. Dozens of major domestic production plants can meet domestic production needs. In addition, horizontal kneaders are often used in the processing and production of soft polyvinyl chloride products. This model is only suitable for unit operation in small factories and is currently mostly used in the production of plastic shoes.
Temperature control to ensure product quality
The heating equipment in the plastic processing process mainly refers to the temperature heating controller of the barrel mold and the calender roll of production equipment such as extrusion, injection molding, and calendering. At present, the heat-conducting oil electric heating method is generally used to replace the complicated steam heating method.
Mold temperature cooler is mainly used to cool the mold temperature of injection molding. Generally, there are cooling water channels in the mold design. Refrigerators are divided into air-cooled and water-cooled types. The air-cooled type is portable, but has low heat exchange capacity. The water-cooled type has a large heat exchange rate and a good heat exchange effect, and is widely used.
Recycling reduces production costs
The proportion of scrap in plastic processing is about 5% to 20% of the total production. It can be said that the recycling of scrap to a certain extent determines the lifeblood of the enterprise. Plastic processing companies are paying more and more attention to this. At present, the most widely used SWP series plastic crusher is divided into equipment suitable for crushing hard products and small-volume products; crushing equipment used for the recycling and granulation of soft plastic foam; used for longer pipes and profiles Crusher for direct crushing and granulation of products; agglomerator for recycling waste silk. In the plastic recycling equipment, it is now moving towards the development direction of low noise, easy operation, continuous tube conveying and discharging of collecting hopper.
For the continuous pulverization of large parts, in order to prevent the plastic parts from being turned and cut for a long time in the pulverizer, the heat generated makes the plastic into an elastic state, which is difficult to pulverize. Domestic manufacturers have developed The crushing equipment with water-cooled jacket ensures the continuous operation and efficient crushing of large plastic parts.
In recent years, due to the domestic production of wholly foreign-owned and Sino-foreign joint ventures, the quality and grade of these plastic processing auxiliary equipment have been greatly improved. The production of high-end products has been maintained at the same level as foreign products, and the price is lower than foreign products. , Has certain competitiveness at home and abroad.
However, there are few plastic processing auxiliary equipment with low usage and high technical content in China. For example, online testing equipment, online printing, computer online control system, etc. still need to rely on foreign products, including online pipe outer diameter measurement devices , Β-ray online measurement film thickness measuring device, inkjet printer, computer automatic temperature, pressure, speed and torque measurement system for extruder and single board machine for injection machine, etc. These plastic processing auxiliary equipment ensure the high quality and precision of the produced products. With sophisticated online testing equipment, you can get sophisticated products and reduce the scrap rate. Domestic companies should strive to make new breakthroughs in this field.