The hottest plastic packaging and roller

  • Detail

Plastic packaging and roller

different processes should choose different rollers

compare the measured and the same kind of unit quantity through a certain measurement method. Roller, especially mirror roller, is an indispensable and important part for the equipment of plastic packaging industry. Whether it is calendering, extrusion or tape casting, it is inseparable from roller. The surface accuracy and quality of roller manufacturing, the rationality of internal channel structure and the processing accuracy will directly affect the quality of plastic products, especially for plastic films. Therefore, it is particularly important for plastic film manufacturers to provide a high-quality roller. There are many kinds of rollers, and all of them have their unique functions. According to the process flow, they are divided into calendering rod, calendering rod, casting roller, etc., according to the functional use, they are divided into heating roller, cooling roller, guiding roller, idler, etc., and according to the structure, they are divided into seamless steel pipe roller, forging and centrifugal casting roller, etc. In short, different processes of plastic products require different rollers. Therefore, as a roller manufacturer, in the process of undertaking roller manufacturing, it should design and manufacture corresponding rollers for different products and different processes, so as to ensure that the roller plays its normal role in the production process. No matter what process is adopted, the structure, design, material selection and processing and manufacturing of the roller shall meet the following basic requirements:

1. The roller shall have sufficient rigidity to ensure that the bending deformation does not exceed the allowable value under heavy load

2. the surface of the roller shall have sufficient hardness, which is generally required to reach HRC50 degrees or above, with strong corrosion resistance. The coating has anti stripping ability to ensure that the working surface of the roller has good wear resistance and corrosion resistance

3. the working surface of the roller shall be finely machined to ensure dimensional accuracy and surface roughness. The roughness should be above ra0.16 without pores or grooves. The wall thickness of the working surface of the roller shall be uniform, otherwise the temperature of the roller surface will be uneven and the product quality will be affected

4. the material of the roller should have good thermal conductivity. Usually, chilled cast iron is used. In special cases, cast steel or molybdenum chromium alloy steel is used, which can achieve rapid and uniform heating or cooling

5. The roller design should be easy to process and low cost

special requirements for rollers in the production of film products

in the calendering and extrusion process, the rollers usually bear a large pressing force and produce a certain separation force relative to the products, making the rollers like cylindrical beams supported on bearings at both ends. Therefore, the deformation cannot be calculated by the bending theoretical formula of general beams, but the maximum deformation can be calculated by the formula of total deflection (including bending deflection and shear deflection). It has been proved in actual production that the total deflection in the middle of the roller is far greater than the allowable tolerance of the product, so we must try to compensate it, otherwise it will not meet the requirements of product accuracy. Since the deflection is the largest in the middle of the roller and the two ends are small, the products are thick in the middle and thin at both ends. Therefore, there are usually three methods of deflection compensation, namely, the medium height method, the preload method and the preload device

in order to eliminate the situation that the product is thick in the middle and thin on both sides, consciously process the working surface of the roller into a waist drum shape with a large middle diameter and a small diameter at both ends. The difference between the maximum diameter at the middle and the minimum diameter at both ends is called the medium height E. Of course, the most ideal medium height curve shape should be the deflection curve of the roller. 1. Pressure testing machine needle printer. However, due to the difficulty of machining, circular arc or elliptical electronic universal tension machine is often used to repair a part of the circle to compensate approximately

in fact, an accurate mid height curve is also unnecessary, because there are many factors that affect the magnitude of the transverse pressure. When these factors change, the transverse pressure changes, and the deflection changes accordingly. Therefore, the fixed mid height compensation method has great limitations and is generally not used alone. Because the medium height compensation method is simple and easy, it is widely used. When there is no other compensation method to match the different re tension range of the roller, the height is within the range of 0.02 ~ 0.10mm, and when used with other compensation methods, the medium height is within the range of 0.02 ~ 0.06mm. At present, when making medium height, general manufacturers turn the grinding head of the grinder to an angle according to the requirements of medium height, and grind it from both ends to the middle. In this way, an angle peak will often be formed. Both sides are straight, and there is no medium height curve. However, the large-scale CNC roller mill currently used by some enterprises adopts the computer automatic control console to carry out the curve movement, so that the grinding roller surface is a curve shape, which can basically conform to the deflection curve and meet the requirements of plastic products production

strictly implement the roller manufacturing process to ensure the quality of rollers

at present, there are many roller manufacturers in China, but there are few manufacturers that can really provide high-quality rollers. The reason is that to make a high-quality roller, the manufacturing process must be strictly implemented. There is no intermediate process. On the surface, the roller can be made, but in the actual use process, serious quality problems will be exposed, affecting the normal production of the manufacturer. Therefore, to do a good job of a high-quality roller, first of all, we should strictly select the roller blank materials. We should choose seamless steel pipes or forgings or centrifugal castings according to different plastic product processes. In the manufacturing process, we should adopt corresponding heat treatment processes such as tempering and tempering for different roller blanks; Secondly, in the processing process, it is also necessary to eliminate the stress after the welding process. In order to improve the surface hardness, carry out surface quenching or nitriding treatment and other processes. These processes must not be removed because of the high cost, which seems to be invisible on the surface, but there are serious hidden dangers in the actual use and production process, which is absolutely not allowed in the roller manufacturing. In addition, in the process of electroplating and surface treatment, the moderate coating thickness should be strictly guaranteed. In the process of grinding, especially in the process of superfinishing, the process steps should be strictly followed. Never save time and ignore the normal steps to reduce the process, otherwise there is no way to produce qualified rollers

Copyright © 2011 JIN SHI