Comparison Between Counter Rotating Conical Twin-screw Extruder and Parallel Twin-screw Extruder

Ningbo Fangli Technology Co., Ltd. is a mechanical equipment manufacturer with nearly 30 years’ experiences of plastic pipe extrusion equipment, new environmental protection and new materials equipment. Since its establishment Fangli has been developed based on user’s demands. Through continuous improvement, independent R&D on the core technology and digestion & absorption of advanced technology and other means, we have developed PVC pipe extrusion line, PP-R pipe extrusion line, PE water supply / gas pipe extrusion line, which was recommended by the Chinese Ministry of Construction to replace imported products. We have gained the title of “First-class Brand in Zhejiang Province”.

According to the rotation direction of twin-screw extruder, it can be divided into two types: co rotating extruder and counter rotating extruder. Co rotating twin-screw extruder means that the rotation direction of two screws is the same when they work; The opposite direction extruder refers to that the rotation direction of two screws is opposite when they work. Today, we will briefly introduce and compare the characteristics of counter rotating conical twin-screw extruder and counter rotating parallel twin-screw extruder.

Performance and structure characteristics of counter rotating conical twin-screw extruder and parallel twin-screw extruder

1. The similarities between parallel and conical twin-screw extruder are the same, and the conveying mechanism of forced forward material is the same; good mixing plasticization ability and dehydration volatilization ability; basically the same practicability for the molding process of materials and plastic products

2. Differences between parallel and conical twin-screw extruders

1) Diameter: the diameter of parallel twin-screw is the same, and the diameter of small end of conical twin-screw is different from that of large end.

2) Concentric distance: the center distance of the flat twin screw is the same, the two axes of the conical twin screw are at an included angle, and the size of the center distance changes along the axis.

3) Length diameter ratio: parallel twin screw (L / D) refers to the ratio of the effective part length of the screw to the outer circle of the screw, and conical twin screw (L / D) refers to the ratio of the effective part length of the screw to the average value of large end diameter and small end diameter.

The counter rotating conical twin-screw has the following characteristics:

1. Two conical screws are arranged horizontally, and the two axes are installed into the barrel at an included angle. The center distance of the two axes gradually increases from the small end to the large end, so that the two output shafts of the transmission gearbox have a large center distance. Its length and diameter are relatively short. The calculation method is to take the sum of the diameters of the large and small ends of the screw divided by the effective length of the screw thread.

2. The gears and gear shafts in the transmission system and the radial bearings and thrust bearings supporting these gear shafts have large installation space. It can install radial bearings and thrust bearings of larger specifications. Each transmission shaft has a shaft diameter sufficient to meet the transmission torque. Therefore, large working torque and large load-bearing capacity are a major feature of conical twin-screw extruder.

The counter rotating parallel twin-screw extruder has the following characteristics:

1. Due to the limitation of the small center distance between the two screws, the bearing capacity of the stop bearing is related to its diameter. The diameter is large and the bearing capacity is large. Obviously, it is impossible to use a large-diameter stop bearing.

2. The length diameter ratio changes greatly. The calculation method is the effective thread length of the screw divided by the screw diameter. Because the length diameter ratio changes flexibly, it has great advantages in processing technology.

From the above, we can clearly see that the most significant difference between parallel and conical twin-screw extruders is the different geometry of screw barrel, which leads to many differences in knot and performance. Although they have different characteristics, they have their own advantages.

In terms of manufacturing cost, the conical twin-screw has been relatively mature due to its manufacturing process and manufacturing application market. In addition, in terms of manufacturing and processing of supporting reducer, the cost and complexity are much lower than those of parallel twin-screw, which can be clearly seen from the current market price. However, in terms of plasticizing capacity of extruded materials, adaptability of process formula and energy consumption, parallel screw extruder has more advantages than conical twin-screw extruder.

If you need more information, Ningbo Fangli Technology Co., Ltd. welcomes you to contact for a detailed inquiry, we will provide you with professional technical guidance or equipment procurement suggestions.