Brief Analysis the Collapsed Flute of Corrugated Board

 Under normal circumstances, corrugated board made by single corrugated machine rolling , its flute height and the number of flute per 300mm length should meet the national standards, flute shape should be neat and intact. If take flute valley as the origin of the coordinate system, the flute shape should be symmetrical to the left and right, like the alternating current sine wave, undulating oothly, and the flute height is equal and lossless. However, in the production practice, a variety of flute defects often encountered, and thus affect the quality of corrugated carton. Some defects are relatively regular, easy to analyze and adopt corresponding improvement measures, some are more difficult to exclude. as shown in figure 1, parts of collapsed flute ,which is difficult to eliminate, and costs more time to figure out. This article makes a brief analysis to seek the most effective way of exclude through discussion and communication. 1. Characteristics of Part of Collapsed Flute and its Impact on Product QualityCorrugated board local collapsed flute features: first, collapsed flute area changes greatly, as little as a few square centimeters to more than a thousand square centimeters. Second, collapsed flute is periodic, along the direction of the single-sided machine, collapsed flute appeared not exactly the same with periodicity; Third,collapsed flute area along the flute transverse appeared large in the middle while all on both ends; Fourth, there is obvious degumming in the collapsed area, and some thickness is only 30% of the corresponding standard thickness. In mass production. The defect of local collapsed flute will affect product quality. A large number of secondary waste produced, resulting in a substantial increase in manufacturing costs, and enterprises suffer a lot on that. This three, five or seven layers of corrugated cardboard, will inevitably produce waste that its degumming area is greater than the sum of national standard 20 cm squared / ㎡, marginal pressure strength is greatly reduced, the thickness of the cardboard lower than the national standard of printing logo,, and text fuzzy, which seriously impact on the overall quality of the carton products. 2. Analysis of the Main Causes of Part of Collapsed FluteThis collapsed flute defects often appear in the corrugated board produced by finger single-sided machine , the main reasons :(1) The gap between the radius of arc working parts of finger and the outer diameter of the lower corrugated roller is too large. Such as lower corrugated roller peak has been worn down to reduce the outside diameter, or because of repeated repair and grinding, etc., the gap is bound to be too large if still using the original finger.(2) Improper finger installation position, resulting in the radius of arc working parts of finger and lower corrugated roller outer diameter between the upper and lower clearance is not consistent. If the finger is not installed in place, the gap between the upper end or the lower end of the finger and the corrugated roller is too large, and too far away from the pressure roller , so that the working face does not play the  of paper guide.(3) The finger has been partially worn out in use, and part of the working face cannot normally guide paper. From rational analysis, in the process of corrugated base paper in single-sided corrugated machine rolling, once surpass rolling tile stress points (corrugated roller gear meshing points up and down), it is influenced by the effects of the centrifugal force created by corrugated roller operation and emitting water pressure after baking, which can make the shaped corrugated paper roll out of corrugated roller, then mainly use finger tightly holding the shaped corrugated paper, making it tight attached in the surface of the lower corrugated roller to operation. If the radius of arc working parts of finger and the gap between the corrugated roller diameter is too large or inconsistency (except glue place), the paper will not be able to play a guiding , corrugated paper in the radial direction is in free state, away from the flute peak surface of corrugated roller, produce flute peak and valley dislocation, when the corrugated roller and the pressure roller are pressed in operation, the dislocation of the corrugated paper pressed by lower corrugated roller, making glued flute peak irregular gluing with inner linerboard (clip) , form a part of collapsed flute of single face corrugated board. Therefore, under the normal condition of tile roll, to solve the problem of part of collapsed flute of single face corrugated board, the key is to achieve reasonable and consistent clearance between the working parts of finger  and the outer diameter of the corrugated roll. 3. Methods to Eliminating the Collapsed FluteFirst of all, it is necessary to measure or check whether the radius of arc working parts of finger is compatible with the outer diameter of the lower corrugated roller (see figure 2). If there is too much abnormal wear and tear in the finger, the finger should be replaced immediately. When the flute shape of lower corrugated roller reduced after repeated repair and grinding or flute peak of the lower corrugated roller significantly wore out, making outer diameter reduced , the radius of arc working parts of finger shall be reprocessed according to the reduction of the outer diameter of the lower corrugated roller. We realize the configuration of finger radius though practice.  The radius of arc working parts = The actual outer diameter of lower corrugated roller divided by 2+(1.5~1.9) corrugated base paper thickness, among them, type E flute is 1.5 and type B flute is 1.6. 1.8 for type C flute and 1 .9 for type A flute.In order to facilitate wedge guiding, an additional 0.2 to 0.4mm can be added to the arc radius within the range of 10 ~ 20mm above the working parts of finger . The second is the position of finger installation should be appropriate, the gap between the radius of arc working parts of finger and the corrugated roller outer diameter should be controlled in accordance with the different corrugated type (1.5 ~ 1.9) corrugated base paper thickness, and to adjust to the upper and lower clearance consistent. The finger flat surface should be perpendicular to the lower corrugated roller axis. Another is to check if the position of both ends of the finger is appropriate, if the upper and lower ends can withstand, and observe whether its bearing corrugated  is normal, if there is an error, it should be adjusted, grinding or re-manufacturing. Adhesives on corrugated roller, working parts of finger will also affect the normal guide paper, which should be cleaned in time. Apart from this , we need to eliminate the corrugated between the parallel, insufficient temperature, and high corrugated base paper moisture .   --If there is Copyright Dispute about the content, please Contact us to Delete.

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Brief Analysis on Corrugated Board Warping

1. PrefaceCompared with the single machine, corrugated board production line has the advantages of high efficiency, high speed, good quality, but the disadvantage is prone to warping , which has brought many difficulties to the next procedure production, such as printing, slotting and scoring, corrugated board with serious warping cannot be produced in next procedure, resulting in product scrap, production cost increase, affecting the quality of the product. At present, corrugated board produced by corrugated board production line , has generally four types of warping as follows: 1). Upward Corrugated Board Warping2). Arched Upward Corrugated Board Warping3). Downward Corrugated Board Warping4). Arched Downward Corrugated Board Warping Note: The arrow in the figure shows the direction of corrugated board running when corrugated board line is working. 2、Factors that Affect Corrugated Board WarpingThe reasons that corrugated board warping produced by corrugated board production line are complex, and related to the quality of base paper, adhesive formula proportion, production workers . Now we will analyze the reasons based on these three aspects, for your reference. (1) .Effect of Base Paper Quality on Corrugated Board WarpingBase paper moisture content has a direct impact on upward and downward warping of corrugated board , we all know that , there is a law of paper expansion, that is, swelling when absorbing water, shrinking when losing water. In general, this rule much applied for paper horizontal than vertical. The transverse expansion and contraction of paper produced by the cylinder machine is much more obvious than that produced by the paper roll production machine. According to the test of our factory, the corrugated board line production paper, for every 1% of the moisture change, the base paper transverse will have 0.06% to 0.1% of the size change, this data can be used as a general reference, for 1600mm width of web base paper, in the corrugated board production line, the moisture change can reach 5% to 10%. The size change of the cardboard can reach 4.8-16mm. Therefore, in order to produce flat corrugated board, it is necessary to carefully control the paper water, to make linnerboard and inner linerboard water loss rate balance, so that corrugated board out of the machine, each side of the paper shrinkage or expansion is not as much as the other side. If you combine some linner board or inner linerboard that contain more water with the one that contain less water, the paper with more water will shrink more due to more water loss, therefore, warping will be caused. For this reason, correct match of linerboard and inner linerboard is really very important in order to produce flat corrugated board. Generally speaking, corrugated board production made of linerboard, inner linerboard that produced by the same manufacturer with same specifications, could make an ideal effect . (2) .Effect of Adhesive on Corrugated Board WarpingIf moisture content of linerboard and inner linerboard is equal, when heating the base paper on both sides, we must try to balance the water loss. When single-sided corrugated enter double-sided machine, adhesive on the peak of flute makes corrugated base paper moisture increased significantly, the linerboard is contact with the peak of flute of single corrugated after heating, at this point, lower the temperature of the double-sided machine hot plate (if necessary,  shut down a set of steam), the water carried by the adhesive does not drive into the paper, then water loss of linerboard and inner linerboard can be balanced, production of corrugated board will not warp, if double machine hot plate temperature is higher, excess heating on linerboard, it will drive the moisture carried by the adhesive to the inner linerboard, then the degree of shrinkage of inner linerboard will be more than linerboard, resulting in a typical upward corrugated board warping .  (3) .Effect of Production Workers' Operation on Corrugated Board Warping.Due to the moisture content of the base paper, adhesive has a direct impact on corrugated board warping, therefore, production workers, when operating the production line, should wellthe double-sided machine coating amount, production speed, steam pressure, as well as the tension of single-sided corrugated and linerboard, in terms of good gluing performance:1). Gluing volume on double-sided machine should not be too much, usually controlled in 15 - l7g / ㎡.(starch)2) Adhesive viscosity should not be too low, generally controlled in about 50 seconds (coated with 4 cups of determination)3) Steam pressure should not be too high to avoid corrugated board warping, generally corrugated board line production:Three-layer board steam pressure: 0.8-0.9mpaThe steam pressure of the five-layer board is 0.9 1MPa In addition, arched upward and downward warping mainly due to the single side corrugated tension is too big or linerboard tension is too big, production workers should immediately investigate when finding corrugated board arched upward and downward warping , make sure the tension of single-sided corrugated and linerboard into the pad is similar. 3、ConclusionCorrugated board warping is a comprehensive reflection of various factors, in order to produce flat corrugated board, various comprehensive factors should be considered, meanwhile some water spraying device in corrugated board line should be added to eliminate warping. --If there is Copyright Dispute about the content, please Contact us to Delete.

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