The blown film unit is mainly composed of an extruder, head, air ring cooling, traction, roll, and so on. A set of high-quality blown film machines needs the whole process from extrusion to rolling. If any of the links between the design principle and manufacturing quality problems, the quality of the products produced will be greatly reduced, that is, affect the use and sales, this problem should be paid attention to.
1. Improvement of blowing film process
The blown film process mainly refers to some of the main steps of blowing film production, such as extrusion, molding, cooling, traction, volume, etc., its main purpose is to ensure product quality and output, terms of output is an important factor to reduce production costs, many factors affecting output, but easy to increase extrusion, improve traction speed, the main factor is the design and processing level of the head.
Since the number of extruded layers is doubled, the heat absorption area is large, and the plasticization effect is good, the quality of the multilayer plane superimposed head mentioned in this paper will naturally improve. With improved cooling technology, production can be increased by 50%.
(1) Improve cooling technology
The so-called cooling technology will make people think of the wind ring and internal cooling and chiller, this is a common technology, people think that these technologies can increase the yield, but use it to improve the quality, the North American use of cooling technology is mainly to improve the quality, they use ethylene glycol refrigeration units instead of the chiller, put forward the wind ring and internal cooling outlet temperature of 50℃, The aim is to increase cooling and crystallization rates, which will improve the clarity, strength, and toughness of the product, i.e. improve economic efficiency.
In the cooling method, the water cooling effect is the best, but from the point of view of health, medical film and food packaging film is not allowed to use water cooling, even if the cold water roller can not be used, because indoor air and cooling water temperature difference, will make the surface of the cooling roller condensation water vapor, does not meet the health requirements, visible product production workshop must also meet these health requirements.
(2) The plane superposition machine head adopts upper traction rotation
Because the plane stack head is fed from the side, the head cannot be rotated, so it must be rotated by traction. There are several types of upper traction rotation in the world. Although the shape is different, the work is very reliable.
Due to the effect of the rotation principle itself, the film will produce periodic deviation. If edges are not cut during crimping, an electronic correction device should be added.
(3) local heating head to improve the uniformity of the film
There is also an infrared thickness measurement technology in North America, which can improve the uniformity of the film by locally heating the head. It claims to be able to limit the thickness error of the product to 3.5%. Internally, we should view this technology critically.
First of all, given the combined effects of the device and the environment, can we generate an error of 3.5% of the product within the product and 5% of the product within the error, what is the need for an additional $100,000 device in the consumer market to achieve such an achievement? These are questions that users should consider. Obviously, in the packaging film market, high-grade high-quality products must have high-tech, high-quality equipment production, product development should be based on the market, and improve the performance and price of equipment.
2. The application and development trend of blowing film technology
By improving a series of technical levels such as extrusion, molding, cooling, traction, and winding of the blown film machine, we have produced high-quality multilayer co-extrusion film, which is used in all walks of life, such as infusion bags in hospitals and various food packaging bags. In short, high strength, high barrier, and high transparent packaging film are obvious trends. On this premise, improving quality and reducing cost is the main task. With the continuous improvement of the market demand and blowing film technology, the number of co-extrusion layers will be more. But in our country, the specifications of packaging blown film equipment will become miniaturized.
The advantages of small multilayer coextruded blowing film equipment are outstanding
From the effect of the blown film process on product quality, the small multilayer co-extrusion blown film equipment has many advantages.
1) The film quality is good
The film here refers to infusion film, high-barrier film, and other high-grade films. The diameter of bubbles produced by small coextrusion equipment is moderate, and the cold air cooling effect of the refrigeration unit is the best.
In addition, whether traction, rotation, or curling, the finished product has the best surface quality and is not prone to wrinkles.
2) High performance-price ratio
Small devices are not small. The production of this five-layer flat superimposed nose is very large. Small films can be produced through changes in the mouth mold. While improving the quality, its output is 1.5 times of other similar equipment, cheap price, low energy consumption, high production efficiency, low rack height, can reduce the height of the plant, health environment control, can be accepted by more users. Through cost analysis, it can be calculated that if the output of two small devices is the same as that of one large device, the total cost of the two small devices is lower than that of one large device, and the quality of the products produced by the small device is higher than that of the large device.
3) After adapting to the slitter process, excessive slitter will affect the winding effect
At the same time, the equipment can not produce heavy packaging bags and another small cylindrical packaging film. The small machine can blow any specification, any layer, and cut the packaging film in the range of 0~800mm, without modifying any equipment configuration, can produce the most products to meet the requirements of the diversified market, and most importantly, under these specifications and costs, the product has a quality and price advantage, undefeated in the market competition.