The introduction and development of plastic extrusion mould

History of extrusion mould:
The word of extrude consist of the Latin "ex" (left) and "trudere" (push) ，which vividly described the extrusion process of “pressure-driven material through a die molding”. In the processing ,Generally the powder or the the polymer in granular form will be added into the extruder barrel ,then the polymer would moves forward along the spiral groove or barrel under the action of the screw or plunger and melt into liquid. Then pass through the end portion of the barrel die and shape a continuum similar to the mold die. Finally it can mold into the desired shapen product after the cooling stereotypes. Such as various plastic pipe tube,sheet ,plastic window and door,film,decorative baseboard and so on.
The Design Points:
The extrusion mould is the core part of the extrusion production, the technical state of the extrusion molds have direct links with the production stability, extrusion products’ quality ,extrusion production efficiency and the use-life of the mould. The design of TianRui plastic extrusion mould have reflected many advantages. The design of TianRui plastic mould have some key points:
1.Head cavity to be streamlined
TianRui plastic mould to make the materials extrude uniformly along the mould head flow, avoid the overheating due to stagnation of the material ,not appear sharply reduction even no dead ends and stagnant areas in the mould die, but try to make the flow smooth,to achieve a surface roughness Ra value of 0.4μm.
2.Sufficient compression ratio
TianRui plastic mould can design to produce sufficient compression ratio mould die according to the different plastic variety ,which can release a combination of seam caused by the shunt stent, to make the product compact.
3.precise cross-sectional shape
According the the factors of plastic performance,pressure ,density，shrinkage ratio and so on， there is a difference between the sectional shape of the mould die and the product's true cross-section shape. TianRui consider these factors when plastic mould design, so that the mould head can have a reasonable sectional shape.
4.pace compact ,easy disassembly
TianRui plastic mould on the condition of meeting mechanic performance,desgin the compact pace ，tight junction ，evenly heat ，easy disassembly and not to leak materials mould head.
5.Reasonable selection
TianRui mould die used the corrosion,abrasion,high hardness steel ,some even chrome according to circumstances.
History of extrusion mould:
The idea of using screw to pump liquid can trace back to the great ancient Greek scientist Archimedes,he applied it to the city’s defense system . According to the record.the most earliest industrial extruder is invented by Joseph Bramah in 1975. Which consist of a manual plunger and head assembly is used in the continuous production of lead pipe. In history, the first Archimedes screw extruder’s patent is acquired by Englishman Matthew Gray and American John Royle. From the mid-19th century to the present, the extruder is applied to the process of Gutta-percha, rubber, cellulose nitrate and casein. Around 1925, people extruding out various PVC is the symbol of modern extrusion processing technology begins.
Development of plastic extrusion mould:
The polymer extrusion industry in China have been developing rapidly in recent decades. Especially since the reform and opening, Polymer Processing Machinery and Mould Industry have gained remarkable achievement ,its average annual growth rate is higher than the overall national economic growth rate and reached more than two digits. Since 1996 production of polymer products in China has been ranked second in the world. In 2000,the production of polymer products in China reached 21 million tons, the value of Polymer processing machinery industry’s output is 8.529 billion yuan.
On the basis of theory, Chinese scholars have made a greater contribution. Professor Zhu Fuhua from Beijing University of Chemical Technology and Professor Peng Yucheng from South China University of Technology led two research groups started out to study from 1978. After 20 years of endeavor , Made a series of achievements in polymer processing visualization technology, extrusion theory and applications, which has made its own contribution to the extrusion processing technology development .
With the development of computer technology, the application of CAE technology in the extrusion process to research also has been booming. Appear many softwares to simulate in screw extrusion process.