one. Introduction
In recent years, the high speed and high output of extruders can enable investors to obtain large output and high returns with low input. The high efficiency of china plastic extrusion machine is mainly reflected in high output, low energy consumption and low manufacturing cost. In terms of function, screw extruder is not only used for extrusion molding and mixing processing of polymer materials, but its use has been expanded to food, feed, electrodes, explosives, building materials, packaging, pulp, ceramics and other fields. In addition, the “one-step extrusion process” that combines kneading granulation and extrusion molding processes into one is also worthy of attention.
two. What is a plastic mold
The mold design plays an important role in the extrusion molding device. The melt is continuously supplied to it by the pressure of the screw ~3CMPa, and the melt is formed into the extrudate with the desired cross-sectional shape by the mold.
Plastic mold is a tool that is matched with plastic molding machines in the plastic processing industry to give plastic products a complete configuration and precise size. According to the different molding methods, it can be divided into different types of molds.
- Injection mold
It is mainly a molding mold that is most commonly used in the production of thermoplastic parts. The processing equipment corresponding to the injection mold is an injection molding machine. The plastic is first heated and melted in the heating barrel at the bottom of the injection molding machine. Under the push of the plug, it enters the mold cavity through the injection molding machine nozzle and the pouring system of the mold, and the plastic is cooled and hardened to form, and the product is obtained by demolding.
Its structure is usually composed of forming parts, pouring system, guiding parts, push-out mechanism, temperature regulation system, exhaust system, supporting parts, etc., and is made of plastic mold steel. The injection molding process is usually only suitable for the production of thermoplastic products. The plastic products produced by the injection molding process are very wide. From daily necessities to various complex electrical appliances and auto parts, they are all formed with injection molds. One of the most widely used processing methods in the production of plastic products.
- Blow Mold
A mold used to form plastic container hollow products (such as beverage bottles, daily chemical products and other packaging containers). The form of blow molding mainly includes extrusion blow molding hollow molding and injection molding according to the process The principle mainly includes extrusion blow molding, injection blow molding, injection extension blow molding (commonly known as injection stretch blow), multi-layer blow molding, sheet blow molding, etc.
The equipment corresponding to blow molding of hollow products is usually called plastic blow molding machine, and blow molding is only suitable for the production of thermoplastic products. The structure of the blow mold is relatively simple, and the materials used are mostly made of carbon.
- Extrusion Die
A type of mold used to produce continuous-shaped plastic products, also known as extrusion molding head, is widely used in the processing of pipes, bars, monofilaments, plates, films, wire and cable cladding, profiles, etc.
The corresponding production equipment is the china extruder machine. The principle is that the solid plastic is melted and plasticized under the conditions of heating and the screw rotation of the extruder, and is made into a continuous shape with the same cross section as the die shape through a specific shape die. plastic products. Its manufacturing materials are mainly carbon structural steel, alloy tools, etc., and some extrusion dies are also inlaid with wear-resistant materials such as diamond on the parts that need to be wear-resistant.
The extrusion process is usually only suitable for the production of thermoplastic products, which is significantly different from injection molds and compression molds in structure.
- Blister mold
A mold that uses plastic plates and sheets as raw materials to form some simpler plastic products. In the case of softening, it is deformed and attached to the cavity of the mold to obtain the desired molded product, which is mainly used in the production of some daily necessities, food and toy packaging products.
Due to the low pressure during molding, the mold material is mostly made of cast aluminum or non-metallic materials, and the structure is relatively simple.
- Compression mold
Including compression molding and injection molding two structural mold types. They are a type of mold mainly used to mold thermosetting plastics, and their corresponding equipment is a press molding machine.
Compression molding method According to the characteristics of the plastic, the mold is heated to the molding temperature (generally 103°108°), and then the measured compression molding powder is put into the mold cavity and the feeding chamber, the mold is closed, and the plastic is heated under high heat and high pressure. Soften the viscous flow, solidify and shape after a certain period of time, and become the desired product shape.
The difference between injection molding and compression molding is that there is no separate feeding chamber. Before molding, the mold is closed first. The plastic is preheated in the feeding chamber and is in a viscous flow state. Under the action of pressure, it is adjusted and squeezed into the mold cavity to harden and form.
The compression mold is mainly composed of cavity, feeding cavity, guiding mechanism, ejecting parts, heating system, etc. Injection molds are widely used in packaging electrical components. The materials used in the manufacture of compression molds are basically the same as injection molds.
- High expanded polystyrene molding die
It is a kind of mold that uses expandable polystyrene (bead material composed of polystyrene and foaming agent) raw materials to form foam packaging materials of various desired shapes.
The principle is that expandable polystyrene can be steamed in the mold, including two types of simple manual operation molds and hydraulic straight-through foam plastic molds, which are mainly used to produce packaging products for industrial products. The materials for making such molds are cast aluminum, stainless steel, bronze, etc.
three. Development of plastic extruder
- Large-scale and sophisticated
Achieving large-scale extrusion molding equipment can reduce production costs, which has more obvious advantages in large-scale twin-screw granulation units, film blowing units, and pipe extrusion units. The major technical equipment required for key national construction services, the large-scale extrusion granulation unit, one of the three key equipment supporting the large-scale ethylene project, has long relied on imports. Therefore, the process of localization must be accelerated to meet the development needs of the petrochemical industry.
- Modularization and specialization
Modular production can adapt to the special requirements of different users, shorten the research and development cycle of new products, and strive for a larger market share; while specialized production can arrange fixed-point production or even global procurement of various system module components of extrusion molding equipment. It is very beneficial to ensure the quality of the whole period, reduce costs, and speed up capital turnover.
- Intelligence and networking
Extruders in developed countries have generally adopted modern electronic and computer control technology. The ratio of raw materials, the current and voltage of the motor and other parameters are detected online, and closed-loop control by microcomputer is adopted. Some companies have adopted online remote monitoring, diagnosis and control to control the extrusion molding production line. This is extremely beneficial to ensure the stability of the process conditions and improve the accuracy of the product.
Enterprises engaged in the plastic extruder industry should, on the premise of fully understanding the characteristics of the industry and the development trend of the industry, combine the advantages and disadvantages of their own enterprises, spot the development trend of the industry, create development opportunities, and always prepare for the transformation and upgrading of the enterprise. In addition to the three major development trends mentioned above, the industry also pointed out that cold-feed extruders will also become the development trend of the extruder industry, because compared with hot-feed extruders, cold-feed extruders are technically And the operation is more advanced and convenient, and the quality of the products produced is relatively good. However, the design of the extrusion process of the cold feed extruder is still complicated at present, and professional operators are required to judge and analyze.
