Carton printing and slotting machines, molding machines, and various printing die-cutting and slotting and other multi-functional combined machines. With the characteristics of high quality, high education, compact structure, etc., they are widely used by carton packaging companies. Slotting knife is a necessary tool. Its service life directly affects the quality of carton slotting and manufacturing cost. It is one of the problems that need to be improved in the quality management and cost management of similar enterprises.
In today’s fierce market competition with quality and price as the core, this issue is increasingly being paid attention to by relevant business leaders, urging enterprises to tap the potential for innovation, cut costs and increase efficiency, and take the path of connotative development. This article discusses how to improve the service life of slotting cutters.
1. Existing problems The structure and shape of grooving knives at home and abroad are basically similar.
The grooving knife includes two parts: the upper knife and the lower knife. The common upper knife includes arc knife and arc serrated knife; the lower knife has semi-circular acute-angle knife or semi-circular right-angle knife, and semi-circular groove wide ring. . The service life of the slotting knife depends on whether the quality of the cardboard slotting meets the product standard. The quality of grooving generally decreases with the wear of the cutting edge of the tool, resulting in burrs, burrs, chipping and waste. When the product does not meet the standard, the grooving knife needs to be replaced.
Although there are certain differences in the service life of imported and domestic grooving knives, there are some similar problems: one is that the grooving knife (upper knife) can only be used once and has a shorter life; the other is the effect of sharpening and reusing the knife. Poor, the quality of grooving is unstable; the third is the poor wear resistance of the cutting edge, and some of the cutting edge is partially cracked; the fourth is the frequent purchase of new knives, which is expensive and the production cost is high.
2. Analysis of the main reasons
(1) Tool wear is related to the quality of the paper being cut. When the grooving knife is working, the ruler cuts the cardboard while the surface is subjected to relative friction. The sand content in many cardboards is as high as 5% ~ 10%. The sand particles have a strong scraping effect relative to the cutting edge, causing the metal on the cutting edge surface to gradually plastically deform and fall off due to fatigue wear. The life of the tool decreases with the increase of the use time and the increase of the sand content (quartz sand, etc.) and impurities of the cardboard being cut.
(2) The gap between the upper and lower knives after sharpening is unreasonable, and reuse will affect product quality.
1 The form and degree of wear of the upper and lower knives. The upper knife working face a is obviously worn within the range of about 10mm above the cutting edge, the cutting edge of the working face b has a certain amount of wear, the two sharp edges become dull, and the thickness between the two faces a becomes thin; the lower knife working face c is from the cutting edge There is also obvious wear within the range of about 10mm below. There is also a certain amount of wear at the cutting edge of the working face d. The edge of the sharp or right angle knife becomes blunt, and the thickness between the cutting edge of the c face and the corresponding end face becomes thinner.
2 Wear causes the gap between the upper and lower cutting edges to change. Usually people pay more attention to the grinding of working faces a and c, but there is less analysis and research on the gap changes caused by this.
3 The corresponding change in the thickness of the groove width retaining ring is ignored. The effect of using a slotting knife after grinding is poor. This is due to the constant thickness of the groove width retaining ring and the unreasonable gap between the upper and lower cutting edges.
(3) Tool wear resistance is related to material and heat treatment hardness. Wear resistance is related to material hardness and the nature, number, size and distribution of hard spots in the structure. The higher the hardness, the more refined carbides. , The more uniform the distribution, the better the wear resistance.
3. Ways to Improve Life This article mentions some objectively inevitable factors or cutting tools that affect life due to accidental bumps, so I won’t discuss them here. Our subjective effort is a practical solution to solve the problem of reuse of old knives and selection of new knives, thereby prolonging the service life of grooving knives.
(1) Reasonable clearance and grinding of old knives to ensure the effect of reuse.
1. Measure and categorize the wear of the old upper knife. In order to unify the size, standardize the sharpening, and reduce unnecessary cutting edge grinding loss, all the old upper knives are measured, recorded, and classified for grinding.
2. Check and classify the cutting edge of the lower knife.
(2) The preferred material is good and the hardness is high
1. Prevent abnormal cracks on the blade. After forging, the steel can reach the shape of the required tool, and it can also make the internal structure compact and improve the quality of the crystal phase. However, it is required to avoid forging cracks during the forging process. Full consideration is given to avoiding defects such as quenching cracks during the heat treatment process.
2. The purchase of new knives shall be checked and accepted strictly according to the drawings. Carton packaging companies generally purchase new grooving knives through outsourcing and outsourcing. What needs to be paid attention to is that they must be strictly checked and accepted in accordance with the dimensional tolerances, materials, hardness and other requirements specified in the drawings.