The blown film machine, as an important plastic processing equipment, plays a pivotal role in the modern packaging industry. It provides high-quality film materials for various packaging needs by heating and melting plastic particles, and then blowing them into thin films through a series of processes. This article will provide a detailed introduction to the working principle, structural composition, application fields, and development of multi-layer co extrusion technology of blown film machines.
Working principle
The working principle of the blown film machine is relatively intuitive. Firstly, dry polyethylene particles are added to the hopper, and these particles enter the screw by their own weight. Under the rotation of the screw, plastic particles are pushed forward by thrust. During this process, the friction between the plastic and the screw, between the plastic and the barrel, as well as the collision friction between particles, combined with the heating outside the barrel, gradually melts the plastic. The molten plastic is filtered by the machine head to remove impurities, extruded from the die mouth, and then cooled, inflated, pulled, and coiled by the air ring to finally become the finished film.
Structural composition
The blown film machine is mainly composed of an extruder, a machine head, a die head, a cooling device, a foam stabilizer, a herringbone plate, a traction roller, and a winding device. Among them, the extruder is the core component, consisting of a screw, a barrel, a feeding hopper, a reducer, and a driving motor. The driving motor drives the reducer through a belt drive, causing the screw to rotate in the barrel, thus completing the plastic melting and extrusion process. The mold head is responsible for shaping the molten plastic into the initial form of a thin film. Cooling device, including cooling air ring, air duct, and blower, is used to quickly cool the film and ensure its shape and size stability.
Application area
The film produced by the blown film machine has excellent barrier properties, freshness, moisture resistance, and oxygen barrier properties, and is therefore widely used in the field of light and heavy packaging. For example, all kinds of fresh fruits, meat products, Pickled vegetables, fresh milk, liquid drinks and medical supplies need this high-quality film as packaging materials. The film produced by the blown film machine not only protects the product from external environmental damage, but also enhances the overall image and added value of the product.
The development of multi-layer co extrusion technology
In order to meet the special functional requirements of plastic film packaging materials in the production process, multi-layer co extrusion blown film machines have emerged. This device can blow film and co extrude various characteristic materials (such as breathable, waterproof, thermal insulation, toughness, etc.) together to form a multifunctional plastic film. The purpose of multi-layer co extrusion blown film machine is to leverage the advantages of multiple materials and avoid some of the disadvantages of single material or single-layer blown film machines. For example, the co extrusion blown film machine for PP and PE combines the hardness of PP material and the brightness of PE material to produce films with both characteristics. Multi layer co extrusion blown film machines are divided into various types based on the number of layers, such as two-layer co extrusion, three-layer co extrusion, and five layer co extrusion. These devices adopt advanced extrusion units, film bubble internal cooling systems, horizontal traction and rotation systems, and photoelectric automatic correction devices to ensure the high quality and production efficiency of the film.
