Said Confucius, "A craftsman must first sharpen his tools if he wants to complete the job well. Living in a state makes one the wisest of its leaders and the most charitable of its academics." A craftsman must first sharpen his tools in order to complete his work well.
High speed cardboard production line has always been paid attention to by the industry, the slitting part of thin knife is particularly important, and the application of thin knife greatly improves the quality of paperboard. Therefore, it is particularly important to select enough thin knife and its supporting consumables, which directly affects the quality and output of paperboard. The use of slitting cutter improves the quality of paperboard on tile line, so it is particularly important to choose thin cutter and its matching grinding wheel. The slitting cutters are mainly made of tool steel and cemented carbide. The main components of cemented carbide slitting knifes are tungsten, carbon and cobalt, which are made by powder pressing and sintering.
Classification and parameters:
A. Tool steel
1. W6mn5cr4v2 -- high speed tool steel(Sharp steel)
2. Cr12 -- Cr12 chromium steel (die steel)
3. 9SiCr-9 alloy tool steel (tool steel)
Although the Rockwell hardness of the above tool steel slitting knives after quenching treatment is not much differnce, the raw material prices and manufacturing costs vary greatly due to the different chemical elements of the steel. However, in the market, many manufacturers choose the Sharp steel knife because of its high temperature resistance, good toughness and unique red hardness. The edge of the blade is kept sharp and durable. Compared with other tool steel and die steel thin knives, its performance is superior, but the price is also higher.
B. Cemente Carbide
Cemented carbide can be divided into tungsten cobalt and tungsten cobalt titanium. Generally, tungsten cobalt (YG) is most produced as the cutting tool. The raw material and manufacturing cost of this kind of blade are relatively high. It has high hardness, good wear resistance and longer service life, but it is expensive and it has no toughness and low bending strength. Tungsten steel thin knife is a kind of high quality cutting tool specially developed for carton industry users. By adding various additives to conventional tungsten steel grades, tungsten steel thin knives have the properties of high wear resistance, high strength, fatigue resistance and non fragmentation. Good machining precision: with excellent equipment and exquisite technology, the surface of tungsten steel thin knife is as smooth as a mirror, and the inner hole, parallelism and end face runout are controlled in a good range. Long service life: the service life of tungsten steel thin knife is between 4 million and 8 million running meters, several times higher than that of sharp steel knife, with high cost performance.
C. How to choose in performace and advantages?
How to purchase the slitting cutter reasonably depends on the equipment condition. For some old equipment, it is recommended to use the thin knife of Shape steel, because these equipment usually can not meet the accuracy required by cemented carbide blade.
Low speed slitter scorer machine (less than 60m / min) can also avoid selecting high-speed shape steel thin knife. Die steel thin knife also has better performance price ratio, which is more suitable for single machine with small work load.
For manufacturers with good equipment, of course, the use of Cemented carbide thin knife is the best choice. It has an ultra long service life and short grinding time, thus greatly reducing the number of times to stop and change tools in the production process, saving time and labor, and greatly reducing the production cost.
D. Cutting Tools Selection in Total
The knife is only an accessory in the whole machine, but the cutting from the base paper to the corrugated board and to the carton is finished by the cutting tool. How to select the cutting tool can be referred to in the following aspects:
1. 9SiCr and SKDII can be selected as slotting cutter. The hardness of the former tool is hrc58 Ο to 60 Ο and that of the latter is HRC61 Ο to 63 Ο. However, the wear resistance of the latter is higher than that of the former, and the service life is several times longer than that of the former. Of course, the price is also relatively high. During tool assembly, the liner between the upper and lower cutters of slotting cutter must be well matched, and the tolerance fit clearance should be within 0.05mm. In addition, the smoothness and parallelism of the upper and lower knives, as well as the blade shape and tooth shape of the upper knife, have certain relations, otherwise the quality of the carton cut out is difficult to achieve the desired effect.
2. With the continuous update of technology, slitting thin knife has replaced the previous paper knife. The slitting blade is generally made of the following materials, SKDII, w6cr5mo4v2 (high speed steel) and cemented carbide. Due to the high sand content of corrugated board produced by development countries' paper processing, the service life of thin knife and the cutting quality of paper are affected.
If the cemented carbide thin kinfe is selected, the requirements for price, quality and use situation are all very high. Its hardness is above hrc75 Ο and its service life is more than 4 million meters. However, special attention should be paid to the installation of the knife. When installing the knife, the force should not be too large and any dust should not be stuck. It is better to use paper pad on both sides of the blade to avoid metal direct collision, resulting in tool breakage. When using the thin knife, the angle of the cutting edge should be between 22 ° and 23 ° and the thickness should be 1.2 ~ 1.5mm. Compared with the Japan knife of 1mm thickness, the thin knife has no effect on the quality of paperboard cutting.
SKDII knife is used for 60 m / min low speed machine, sharp steel is used for 80-120 M / min medium speed machine, and cemented carbide is used for high-speed line above 160 m / min.
There are three kinds of grinding wheel with different heat resistance. The CBN grinding wheel should be selected for SKDII and shape steel, and the formula of CBN grinding wheel is also different. Cemented carbide thin knife should be equipped with diamond wheel. And it is better to have manual grinding function, so that the service life of the tool will be longer.
3. The Cut Off knife l is generally inlaid structure, the body is made of 45# steel and A3, while the cutting edge is inlaid with 6CrW2Si and W18Cr4V(High speed tool steel), The knife angle should be 38-48 degrees, straigth, not bending. The former hardness should be HRC58-60, the later should be HRC 62-65.
