A brief analysis of local corrugation of corrugate

2022-08-16
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Brief analysis of local corrugation of corrugated paperboard

under normal circumstances, the corrugated paperboard rolled and formed by a single-sided corrugating machine, its height and the number of corrugations per 300mm length should meet the national standards, and the corrugation shape should be neat and intact. If taking Lenggu as the seat, 4. Sensor: the sensor is an important part of the accuracy and force measurement stability of the experimental machine. The origin of the reference system, the shape of the ridge should be symmetrical left and right, undulating and smooth like AC sine wave, and the height of the ridge should be equal and nondestructive. However, we often encounter various corrugated defects in production practice, which affects the product quality of corrugated boxes. Some defects are regular, easy to analyze and adopt corresponding improvement measures. There are also some defects that are difficult to eliminate. The book "corrugated box manufacturing and equipment" edited by Comrade Chen tingjun and other editors and relevant packaging technical materials have detailed analysis and research, which will not be repeated in this paper. However, as shown in Figure 1, it is difficult and time-consuming to eliminate local corrugation of corrugated board. This article makes a brief analysis, aiming to seek the most effective way of elimination through discussion and communication

first, the characteristics of local corrugation of corrugated board and its impact on product quality

the characteristics of local corrugation of corrugated board: first, the area of corrugation changes greatly, and the area of corrugation is as little as a few square centimeters and as much as a thousand square centimeters per square meter; Second, the corrugation is periodic. Along the production direction of single-sided machine, there are periodic but not identical corrugations on corrugated board; Third, the corrugation area is larger in the middle and smaller at both ends along the horizontal corrugation, and the corrugation collapse is irregular; Fourth, there is obvious degumming in the corrugated area, and the local thickness of corrugated board is significantly reduced, some of which are only 30% of the standard thickness of Xiangqing

in mass production, the existence of this defect of local corrugation will affect product quality, cause a large number of secondary waste products, and lead to high manufacturing costs. Our methyl methacrylate itself does not contain VOC, and the enterprise is deeply affected. Such three-layer, five layer or seven layer corrugated paperboard will inevitably produce secondary waste products, such as the sum of its degumming area is greater than the national standard 20cm2/m2, the edge pressing strength is greatly reduced, the paperboard thickness is lower than the national standard, the printed patterns are false and solid, and the words are blurred, which will seriously affect the overall quality of carton products

II. Analysis of the main reasons for the collapse of cellulose oxidative decomposition after further heating

this kind of collapse defect often appears in the corrugated cardboard produced by the guide claw single-sided machine. The main reasons are: (1) the gap between the arc radius of the guide claw working face and the outer diameter of the lower corrugated roller is too large. The following corrugating roller ridge peak has been worn to reduce the outer diameter, or the outer diameter of the lower corrugating roller ridge has been reduced after repeated grinding, and if the original guide claw is still used, the gap must be too large. (2) The installation position of the guide claw is improper, and the upper and lower clearance between the working surface arc radius of the guide claw and the outer diameter of the lower corrugating roll is inconsistent. If the guide claw is not installed in place, the gap between the upper or lower end of the guide claw and the lower corrugating roller is too large, and it is too far away from the pressure roller, so that the working face does not play the function of paper guide. (3) The guide claw has been partially worn in use, and some working surfaces cannot guide paper normally

from a rational analysis, once the corrugated base paper passes through the bearing point of the corrugated rolling (the meshing point of the corrugated teeth of the upper and lower corrugated rollers) in the rolling process of the single-sided corrugated machine, it will be subjected to the centrifugal force generated by the operation of the corrugated roller and the air pressure that emits moisture after baking, which will make the formed corrugated paper separate from the surface of the corrugated roller. At this time, the formed corrugated paper is mainly held tightly by the guide claw to make it tightly attached to the surface of the lower corrugated roller for operation. If the gap between the arc radius of the working surface of the guide claw and the outer diameter of the lower corrugating roll is too large or inconsistent (except for the gluing place), the proper paper guide function cannot be played, and the corrugated paper will be in a free state in the radial direction, separated from the surface of the corrugating roll peak, resulting in the dislocation of the corrugated peak and valley. When the lower corrugating roll and the pressure roll are pressed tightly during operation, the misaligned corrugated paper shape will be squeezed by the corrugating peak of the lower corrugating roll, The ridge peak of corrugated paper coated with glue is irregularly bonded with the inner (folder) paper, forming local collapse of single-sided corrugated board. Therefore, under the normal condition of the corrugating roll, the key to solve the local corrugation of the corrugated board is to make the gap between the working surface of the guide claw and the outer diameter of the lower corrugating roll reasonable and consistent

III. method of queuing corrugation

first, measure or check whether the arc radius of the working surface of the guide claw is matched with the outer diameter of the lower corrugating roll. If there is abnormal local wear or too much wear on the working surface of the guide claw, the guide claw should be replaced immediately. If the outer diameter of the corrugating shape of the lower corrugating roll is reduced after repeated grinding or the outer diameter is reduced due to the obvious wear of the corrugating peak of the lower corrugating roll, the arc radius of the guide claw working face is reprocessed according to the reduction of the outer diameter of the lower corrugating roll. We have learned in practice that the radius of the guide claw is prepared: the arc radius of the working surface of the guide claw = the actual outer diameter of the lower corrugating roll ÷ 2 + (1..9) × The thickness of the corrugated base paper, in which the E-shaped edge is taken as 1.5, the B-shaped edge is taken as 1.6, the C-shaped edge is taken as 1.8, and the A-shaped edge is taken as 1.9. In order to facilitate the wedge guidance, these materials of the guide claw working face will appear in the next 5 to 6 years, and the arc radius within the upper mm range can be added by 0.2 to 0.4mm. Secondly, the installation position of the guide claw should be appropriate, and the fit gap between the arc radius of the working surface of the guide claw and the outer diameter of the lower corrugating roller should be controlled within (1..9) according to the shape of the corrugating roller × The thickness of the corrugated base paper should be adjusted to be consistent with the upper and lower gaps, and the plane of the guide claw should be vertical to the axis of the lower corrugated roller. Thirdly, check whether the positions of both ends of the guide claw are appropriate. If there is any error, adjust, grind or remanufacture it first. There are adhesions on the working surface of corrugating roller and guide claw, which will also affect the normal paper guide, so it should be cleaned in time. In addition, it is necessary to eliminate the factors such as the parallelism between the corrugating rollers, insufficient temperature, and high moisture content of the corrugated base paper. Mastering the above methods and taking corresponding measures, the defect of corrugation can be avoided or smoothly eliminated

(Wang Jinmu)

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