Discussion on the influencing factors of the press

2022-08-24
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Discussion on the influencing factors of the pressing and forming process of cigarette box II

2. The influence of the arrangement direction of paper fibers on the indentation effect

paper is usually made by draining water from a thin sheet of plant fibers. In the process of papermaking, a large number of fibers form the same arrangement as the running direction of the machine. When the indentation direction is parallel to the paper fiber direction, we call it along grain (MD), and when the indentation direction is perpendicular to the paper fiber, we call it straight grain (CD). Therefore, the force required for indentation in CD direction is greater than that in MD direction. The rebound coefficient of CD direction trace is 20% higher than that of MD direction trace under the condition of constant groove width and pressure. Therefore, when designing the indentation line, the arrangement direction of paper fibers must be considered to determine the indentation pressure. When designing the width of the indentation groove, the MD direction should be smaller than the CD direction

from the above discussion, it can be seen that indentation is the key to the packaging and molding of hard box cigarettes. For easy packaging, bauschinger (Bauschinger) found the cyclic softening phenomenon of the decline of elastic limit under cyclic load when verifying the wlex fatigue test, and introduced the concept of stress-strain hysteresis loop, the ideal indentation line, to ensure the appearance quality standard of cigarette packaging, many factors such as mold and paper that affect the quality of the indentation line must be excluded in the mold design, manufacture and pressure adjustment, The pressed trace line is neither broken nor easy to fold, which is suitable for the production of high-speed packaging. The mechanics of indentation is that when the die-cutting die presses the paperboard into the groove, the paperboard receives two kinds of forces, namely, internal fracture and the increase of surface tension. No one has ever tested the force accuracy: <1n will doubt the safety of these devices. What we need to do is how to control these two forces. It can be seen in the figure that distance is the key to making indentation

according to the feedback on the packaging quality of cigarette labels with flip Hard boxes produced by bobst820 unit (flat pressing and die cutting), there are quality defects such as small box stiffness and "double eyelids" in the cigarette factory. The mold configuration is: German Marbach sandwich upper mold, the steel wire specifications are 23.80mm (height) x0.71mm (top thickness) and 23.85mmxo.71mm respectively, the lower mold adopts steel female mold, the width of trace groove is 1.2mm and 1.4mm respectively, the CD direction and MD direction adopt the same groove width, and the paper thickness is 0.3mm

when indenting, the top of the steel wire is on the same plane as the female mold steel plate, and the pressure to form the trace line mainly comes from the thickness of the paper. Sometimes, in order to achieve better molding effect, 23.85mm steel wire is even used. Although the top of the steel wire is 0.05mm deep into the slot, because the paper fiber is not damaged, the average rebound force of the indentation line reaches more than 0.833n, and some even reach more than 0.931n, which makes it unable to meet the quality requirements of cigarette packaging

according to experience and a large number of tests, it is considered that the paper stiffness in MD direction is relatively low because the indentation line is parallel to the paper fiber paper, the force required for crease is small, and the slot width B is 1 ~ l.1mm. More appropriate. The indentation line in the CD direction is perpendicular to the paper fiber, and the paper stiffness is high. In order to basically keep consistent with the rebound force in the MD direction, it is appropriate to increase the slot width b to 1.1 ~ 1.2mm. When the distance a reaches 0.2 ~ 0.26mm, the internal fibers of the paper are destroyed and broken, and the rebound force of the indentation line drops below 0.735n, which fully meets the requirements of cigarette packaging

design of die cutting indentation

in order to obtain excellent trace lines, the following factors must be considered:

① paper type,

② paper thickness,

③ steel wire height,

④ bottom groove width,

⑤ steel wire top thickness,

③ paper grain to design the mold

it can be seen that only excellent and scratched indentation lines can ensure the best molding of cigarette packaging. Through the research on the marking line, we can constantly eliminate the adverse factors that affect the quality of the marking line, and produce cigarette labels that meet the requirements of high-speed cigarette packaging machines and adapt to the image of China's first-class cigarette products. Whether the mold is designed well or not will directly affect the excellence of the bottom line. Mold design is the premise. Therefore, various factors affecting the trace line should be considered as much as possible in mold design, and eliminated through design. Of course, the mold design may not succeed at one time, which requires the analysis of products and the continuous accumulation of experience, so as to determine the best combination point of the steel wire height, top thickness, groove width and paper type, thickness and grain required by the mold

d1e3cb weight: 10kg2

(text/Sun Jianfa Chao Feng)

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