How To Choose Parallel And Conical Twin Screw Barrel, Please See Here ~

How to choose between parallel twin screw barrel and conical twin screw barrel in production and use? Is the user in the purchase of twin screw barrel will often raise the question.

Classification of twin screw barrel:

According to the rotation direction of the twin screw, it can be divided into two kinds: the same direction and the opposite direction. The same direction screw barrel is the same rotation direction when the two screws work, and the opposite direction screw barrel is the opposite rotation direction when the two screws work.

According to the parallel axis line of the twin screw, it can be divided into two kinds of screw barrel parallel axis line and axis line intersection. The parallel twin screw barrel with parallel axis lines and the cone-shaped twin screw barrel with intersecting axis lines are used.

Twin screw barrel and meshing and non – meshing points.

Similarities between parallel and conical twin screw barrel:

Both have the transport mechanism of forced forward plastic, good mixed plastifying capacity and dehydration capacity, with basically the same adaptability to the material and plastic molding process.

The difference between parallel and conical twin screw barrel:

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 is an Angle, the size of the center distance changes along the axis;

3)Aspect 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 of the diameter of the large end and the diameter of the small end.

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

The parallel twin screw barrel is limited by the small distance between the center of the two screws. In the transmission gearbox, the space for the radial bearings and thrust bearings supporting the two output shafts and the related transmission gears is very limited. Although the designer tries his best, he can not solve the reality of the bearing capacity, the modulus and diameter of the gears, and the small diameter of the tail of the two screws. Results in poor torsion resistance. Small output torque and poor load resistance are the most significant defects of parallel twin screw barrel. However, the plasticity of aspect ratio is the advantage of parallel twin screw. It can increase and decrease aspect ratio according to the difference of forming conditions to adapt to the requirements of plastic processing technology, and can expand the scope of application of parallel twin screw, but this conical twin screw barrel is difficult to do.

The two conical screw barrel are arranged horizontally, and the two axes are loaded into the barrel at an Angle. The center distance of the two axes is gradually increased from the small end to the large end, so that the two output shafts of the transmission gearbox have a large center distance. The gears and gear shafts in the transmission system, as well as the radial bearings and thrust bearings supporting these gear shafts, leave a large space for installation. It can be equipped with large specifications of radial bearings and thrust bearings, each drive shaft has enough to meet the transmission torque diameter, so large working torque, large load bearing capacity is a major feature of conical twin screw barrel. This parallel twin screw barrel is incomparable. When the twin screw barrel works, the melt will produce a very large pressure (head pressure) in the screw head. The pressure is usually about 14MPA, and sometimes even up to 30MPA or more. This pressure forms a strong axial thrust on the screw, and the thrust is the function of the back-off bearing.

The parallel twin screw barrel is limited by the small distance between the center of the two screws, and the bearing capacity of the check bearing is related to its diameter. If the diameter is large, the bearing capacity is large, so it is obviously impossible to use the check bearing with large diameter. This contradictory situation is usually to use several small diameter check bearings in series to work together to bear strong axial force. The core problem of using this method is that the load borne by each thrust bearing must be uniform and the same, otherwise, the bearing with large bearing is damaged in advance due to overload, and the load it should bear is added to other bearings to make it overload. The consequences of this disruption of continuity are very serious. It can be seen that the structure of the parallel twin screw barrel transmission system is more complex, and compared with the structure of the conical twin screw barrel transmission system, the manufacturing cost of the gearbox is high, and the maintenance is more complex.

Conical twin screw barrel because the arrangement of the two screws has an Angle, so the two output shafts of the transmission gearbox have a large center distance, in the gear box is equipped with two front and back stagger arrangement of larger thrust self-aligning ball bearings, enough to prevent the axial force formed by the pressure of the head, its characteristics of large bearing capacity, low manufacturing cost of the gear box, more convenient maintenance.

For users, the selection of twin screw barrel is very important, different types of twin screw barrel has different performance and application, therefore, it is necessary to figure out the performance and application of various twin screw barrel. For example, because of its high speed, high shear rate, combined screw, it is widely used in the modification of polymers that are not easy to thermal decomposition — blending, filling, fiber reinforcement and reaction extrusion of materials. For example, the meshing type cross-rotating twin screw barrel, because of its good mixed plasticizing function, its biggest feature is the direct molding processing of PVC powder. If the geometric structure of the screw is changed, it can also be used for the molding of other materials, but its strength is still PVC molding. According to the size of the plastic section, determine the extrusion volume, and then choose the specifications of the twin screw barrel by the extrusion volume. In the plastic processing and molding process conditions are basically the same, the conical twin screw barrel can adapt to the larger head pressure, the parallel twin screw barrel can adapt to the smaller head pressure.

Zhoushan Jed Machinery Co., Ltd. was established in 2013, located in the coast of the East China Sea, adjacent to the international famous deep water terminal Ningbo Beilun Port, committed to single screw, twin screw processing and manufacturing for nearly 10 years, the company set design, production, sales in one, has provided professional screw barrel production technical services for thousands of enterprises. Nowadays, our company is developing towards the direction of energy-saving, high-precision and high-strength screw barrel. We individually design and manufacture screw equipment with different process requirements for customers.

Our company specializes in manufacturing series of screw barrel products, suitable for domestic, imported 30~40000 grams of injection molding machine, 15~250mm single screw extruder, 30~130mm conical, parallel twin screw extruder and rubber machinery, chemical looms, food machinery and so on. Using high quality steel 38CrMoALA, products through quenching and tempering, qualitative, nitriding, fine grinding, polishing and other sophisticated manufacturing process, strict reference to ISO9002 international quality control system, products up to (national) standards. At the same time the production of GH113 nickel base alloy (new 3# steel) screw barrel, also can spray welding alloy (PTA bimetal), the company in addition to domestic and foreign complete machine factory to provide supporting, but also to undertake the occasional customer letter to sample processing business, and can assist in surveying and mapping, design. The company is dedicated to provide the best products and services for the majority of users, the company is equipped with strong technical support, and established a perfect after-sales service system, to provide guidance and help for the problems and difficulties encountered in the development of enterprises. Our continuous efforts and pursuit, will be able to mutual benefit and win-win with you, hand in hand! Welcome new and old customers to visit and inquire! WhatsAPP/WeChat:+8613567672668,Email:[email protected]