Process improvement of the hottest corrugated boar

Improvement of corrugated board production line process

since the 1980s, China's packaging industry has mushroomed into a relatively complete system and has a considerable scale, ranking 16th among the 40 industries of the national economy. Due to the increasing awareness of protecting human living environment, corrugated boxes have always been the most popular packaging material in the packaging industry on the stage of the packaging industry, and they are also widely used containers for the circulation of materials in general manufacturing industry. It can be seen almost everywhere. However, as long as you pay attention, you will find that some cartons are either damaged, or staggering, and even peeling and brittle, Most of the reasons are due to According to incomplete statistics, the number of corrugated board production lines in China increased from 18 in 1980 to 181 in 1990, of which 113 were introduced from the United States, Japan, Italy and other countries.

from 1990 to 1999, the technology of domestic paperboard production lines gradually matured, and the number of domestic paperboard production lines on the national market increased sharply. In the past decade, about By adding 100 production lines, the number of domestic paperboard production lines has reached 1300, and computer control has been widely used, developing towards large-scale and high-speed. However, up to now, the heating plate of the dryer in the paper board production line still cannot adapt to the changes of various grades, weights, speeds, etc. of paperboard. Due to the proposed composition design of domestic aluminum alloy with high strength, high toughness and low quenching sensitivity and the microstructure control criteria in the manufacturing process, the economic benefits of the equipment still have potential to be tapped. Here, only some reasonable suggestions are put forward for the deficiencies of some processes of the dryer

I. the heating and pressurizing mechanism of the conventional double-sided dryer of the domestic corrugated board production line is composed of a fixed heating plate and a gravity roller pressure device. When the machine speed changes, the heat transfer of the two devices is a fixed value. In the process of producing paperboard, the heat of the hot plate is adjusted by steam pressure according to the paper grade, quantity and thickness to meet the heating requirements of different paperboards. However, in the production process, especially in the production of medium and low-grade corrugated cardboard, due to insufficient cardboard tension, the original joints, gaps and broken ends often change the running speed of the cardboard production line (there is no fully automatic paper receiving device). Any significant speed change will break the balance of heat transfer, and the conventional double-sided dryer hot plate is fixed in Zhejiang Province to accelerate the major technological breakthrough of new materials, which cannot be adjusted. At this time, the paperboard is in the state of heating and pressurization at the "ten time", and excessive heat causes the paperboard to be overheated, resulting in excessive horizontal shrinkage (warping), brittleness and washboard shape of the corrugated paperboard, and even cracking at the pressing line, which eventually leads to the reduction of the compression strength of the formed corrugated paperboard, inaccurate printing overprint, carton damage and other defects

Figure 1 hydraulic lifting schematic diagram

2. According to the heat transfer balance, the heat supplied to corrugated board in the hot plate must adapt to the running speed of corrugated board production line. The type of base paper, which is the key to making cardboard with uniform texture, non bending and non crisp. The fixed heating plate of the double-sided machine in the corrugated board production line can be designed as a set of hydraulic lifting variable heat heating system. Because it is impossible to change the temperature of the hot plate in actual production, we can only adjust the inclination of the hot plate to make the hot plate form a wedge with a corrugated board, and produce a certain gap to dissipate part of the heat from the gap, so as to reduce the heat supplied by the hot plate to the corrugated board, achieve the purpose of heat transfer balance, and ensure that when the corrugated board passes through the double-sided dryer, the heat supply can be effectively adjusted according to the drying requirements of different corrugated boards, Ensure various technical indicators of corrugated board. The working principle of hydraulic lifting is shown in Figure 1

figure II schematic diagram of compartment heating plate drying method

figure III. The corrugated board production line of the existing fixed hot plate device cannot be transformed into a variable heat heating system (if it is to be transformed, unless a large amount of money is invested in the transformation), a set of air injection system can be designed, that is, the interlayer heating plate drying method. It is designed and installed with a narrow nozzle at the gap between the hot plates, and uses a group of air regulating valves to adjust the opening and closing angle of the valve according to the running speed of the cardboard, so as to control the amount of air injected by the nozzle. The air forms a thin air layer between the hot plate and the corrugated cardboard, so as to reduce the heat transfer between the hot plate and the corrugated cardboard. Its principle is to open the regulating valve when the running speed of the corrugated cardboard production line decreases, Make the air between the blowing hot plate and the paperboard diffuse to form a sheet-like air strand that can just lift the corrugated paperboard and the canvas belt from the hot plate, so as to reduce the transfer of excessive heat from the hot plate to the paperboard (see Figure 2 for details)

(author unit: the sales of new energy vehicles decreased sharply in January, and yanghuangguoshu Paper Co., Ltd.)