Causes, countermeasures and effects on the quality of BOPP film slitting quality ---
(2) The purpose, method and characteristics of hardness testing
3. Method for detecting film roll hardness
1 selection of testing equipment
There are various instruments for detecting the hardness of an object, but so far there has not been a hardness tester that professionally detects the hardness of a film roll. Due to the large difference in surface hardness between various objects and the variety of hardness testers, it is important to select a hardness tester that can effectively reflect the tightness of the film roll. After screening and comparison, our company has determined the "A-type rubber hardness tester" for detecting the surface hardness of rubber products as an auxiliary instrument for detecting the tightness of the film roll.
2 detection instrument correction
Since the "A type rubber hardness tester" is not a special test instrument for the film roll, in order to improve the detection accuracy of the instrument, we have modified the structure of the hardness tester according to the characteristics of the film, and increased the presser area by 5 times.
3 detection methods a.
Before the test, the pointer of the hardness tester should be in the free state and point to the zero position. When pressing the hardness tester on the glass plate, the pointer should be 100 degrees (the end face of the press pin and the bottom of the foot are in close contact with the glass). If the zero position and the 100 degree are not indicated, the needle can be pressed slightly several times, if not When referring to zero and 100 degrees, it cannot be used. The hardness tester to be confirmed can be used again if it meets the requirements for use. b.
When testing the hardness, put the hardness tester on the side of the film product, take the left, middle and right positions, at least 40mm from the edge of the film roll, and firmly press the end of the hardness tester with both hands, so that the pressure pin is pressed vertically. The sample is read within 1 s until the pressure is fully contacted with the sample, and the average is taken and recorded.
Reasons, countermeasures and effects of BOPP film slitting quality ---
twelve. Interface quality problem (poor interface quality, interface identifier does not match)
1. Interface requirements
Due to poor interface, the quality of the film roll may be broken or wrinkled, which may cause adverse effects in the user's use. Therefore, the film interface must be connected to the specified specification to ensure the joint quality of the interface. Specific requirements are as follows:
1 The two sections of the joint are cut and flattened horizontally, and the beige (or other specified color) adhesive tape with a width of 72 mm is firmly adhered to the front and back sides of the film;
2 In order to improve the interface quality, the film interface is required to be straight and balanced with the paper tube direction, and the interface is required to be flush and wavy. The interfaces at both ends are in the middle of the tape. Try to avoid the size of the edge. The adhesive tape is attached to the film. No obvious bubbles;
3 The film surface at the interface is required to be smooth without obvious wrinkling;
4 Do the identification of the joint position as specified.
Slitting machine parts ---
2. Attenuation and tension compensation of the tension of the rewinding and unwinding: It is generally believed that maintaining the constant tension of the aluminum foil during the rewinding and unwinding of the aluminum foil is beneficial to the apparent quality of the finished aluminum foil, but it is not. The best method is to increase the tension of the aluminum foil according to a certain rule as the diameter of the coil increases, and the smaller the diameter, the lower the tension value. There are automatic tension control and manual tension control during the slitting operation. The automatic tension control system is the leading set tension attenuation value, which is maintained throughout the winding process. The manual tension control requires the operator to continuously adjust the diameter of the master roll to meet the tension required for the aluminum foil during operation. When setting the automatic tension operation, set the initial tension before setting the tension attenuation value. Taking the setting of the slitting and unwinding attenuation value as an example, the setting principle is that the aluminum foil tension attenuation value (%) is equal to the tension at the end of winding of the aluminum foil minus the initial tension and then divided by the initial tension. Multiply by 100%. When setting the automatic tension value of the unwinding, it should not be too large, otherwise the aluminum foil winding surface has a large hardness and is prone to warping. But the tension should not be too small, too small and easy to cause the rewinding body to be too loose, and the winding is not neatly running. Therefore, the quality of the rewinding and unwinding during the aluminum foil slitting operation is mainly affected by the change of the tension of the aluminum foil. It can be seen that the mastery of the retracting and unwinding control system is the key to affecting the quality.
3. The change of speed during slitting affects the change of tension: When the speed is increased or decelerated, the speed of the main motor changes. Firstly, it causes the instantaneous change of the tension of the unwinding traction to the winding section of the aluminum foil, and it is necessary to slightly vibrate the aluminum foil after a period of time to gradually stabilize the tension. The instability of this tension is manifested in the fact that the finished roll is not well-wound, and the end face has unevenness, which affects the quality of the product.
Zhengzhou EAST IMPORT AND EXPORT co., ltd . ( a goulian group of company) a manufacturer and exporter for all kind of packaging machinery , like bopp tape coating machines, bopp tape slitting machines. Bopp tape core cutter, bopp tape core loader etc