How to control and prevent the quality of corrugated board
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The single-sided machine is the main equipment for the production of corrugated boxes. The quality of the semi-finished corrugated board produced by the single-sided machine directly affects the production cost of the carton. The base paper is the main material for the production of carton. The production cost of the carton comes from about 75%. Raw materials, if the non-conforming products or defective products of corrugated cardboard produced by single-sided machines increase, it means the waste of raw paper and other materials, the increase of production costs, and the decline of production profits. In the current market environment where the carton industry is generally in a meager profit, the production technology of the single-sided machine is controlled, the performance and operation technology of the equipment are controlled, the quality of raw materials is controlled, the quality problems are prevented, and the semi-finished products of single-faced machines are qualified. The rate, its meaning is self-evident.
1. Understanding of the definition of quality standard for semi-finished corrugated board
As a basis for the quality of carton products, the single-sided machine is the basis for the quality of carton products. The quality status of semi-finished corrugated cardboard produced by single-sided machines has three basic characteristics: qualified products, non-conforming products and defective products. Qualified products refer to the quality requirements of corrugated board that fully comply with the relevant standards; non-conforming products refer to the quality requirements of one or more indicators of corrugated board that do not meet the relevant standards; Defective products with slight defects in quality, such as rough edges, different specifications, partial degumming, blistering, collapse, slack, cracking, etc. The above three standards are generally only the definition of the internal standards of the factory. The original national standard for light industry refers to the definition of corrugated board. According to the product quality and the quality grade of raw materials, each corrugated board (three-layer structure) is divided into superior products, first-class products, qualified products and non-conforming products. Among them, the superior products are corrugated cardboard for exporting goods and valuables packaging; the first-class products are corrugated cardboard for packaging domestic products; the qualified products are corrugated cardboard for short-distance and low-priced packaging. The three types of standards are also divided into four standard values to suit the requirements of different product packaging. The original national standard also stipulates that the bonding strength of corrugated board should not be lower than 588N/m; the moisture of corrugated board (according to online moisture) is 14±2%; the appearance quality of corrugated board should be smooth, clean and not allowed. There are missing materials, thin edges, trimming edges should be neat, and the bonding is firm. The sum of the degumming parts is not more than 20cm2 per square meter. A non-conforming product is a product that is judged to be unqualified by the sampling rule. The practice shows that some quality indicators of superior products are unqualified and may become first-class products or qualified products. If certain quality indicators of first-class products are unqualified, they may become qualified products. However, the single corrugated board referred to in the national standard is corrugated board made of two layers of boxboard paper and a corrugated corrugated base paper. The two-layer corrugated board produced by a single unit of single-sided machine has not been subjected to cladding processing, and its bursting strength and edge pressure strength will be greatly reduced. Therefore, the national standard of corrugated cardboard cannot be applied, and so far our country has no single side. The standard of semi-finished corrugated board, the general system of the standard system is to adopt the self-developed enterprise standard to control the semi-finished corrugated board in the production process. However, the enterprise standard is not necessarily detailed, complete and accurate. In practice, It is necessary to pay attention to continuous analysis and summarization in order to carry out appropriate revision and improvement, so that the standard can play a better role in regulating the production process and operation technology.
2. The effect of poor quality of semi-finished products of single-sided machine on post-processing production
After the single-wafer semi-finished cardboard of the single-sided machine is produced, the pre-printed carton paper and the two-layer single-corrugated cardboard are pasted by the laminating machine to form a three-layer structure of the single corrugated cardboard, which can be processed by die-cutting. Made into a finished carton. It can be seen from the characteristics of the processing technology of the back processing of the carton that maintaining the flatness of the corrugated board has a crucial effect on ensuring the quality of the cardboard and the precision of the die cutting. If the semi-finished corrugated board produced by the single-sided machine has obvious warping deformation, it will affect the normal paper feeding of the automatic laminating machine and the accurate positioning of the corrugated board. Some corrugated board has more curl deformation, and the laminator has to deform the warp. The corrugated cardboard is folded in the opposite direction to maintain the flatness required for automatic paper feeding. However, after the corrugated cardboard is broken, the compressive strength of the formed carton is greatly reduced. If the corrugated cardboard of the single-sided machine is warped, the three-layer corrugated cardboard is also prone to arc warping after being applied by the hand-held veneer. When the semi-finished product is die-cut on the die-cutting machine, it will also be given. Normal paper feeding and positioning create certain obstacles that affect the quality of the carton. Therefore, in the single-sided machine production process, we must pay attention to control the moisture and flatness of the online corrugated board, which is the basis for ensuring the quality of the carton.
3. Analysis and control requirements for quality problems in semi-finished products of single-sided machines
The production process shows that the quality of the corrugated board produced by the single-sided machine is good, and the pass rate of the carton quality has a reliable guarantee. In the quality tracking management, the author found that sometimes the raw materials are qualified, but due to the improper control of the production technology and operation technology of the single-sided machine, for example, in order to catch up with the output speed, it is easy to cause the cardboard to be heated for a short time, and the peak of the corrugated Insufficient coating, the forming hardness of the paperboard is lowered, and the problem of a decrease in the adhesive strength is liable to occur. It is worth mentioning that if the single-sided machine with incomplete auxiliary facilities is used, the speed is too fast, because the machine is difficult to adjust the moisture of the base paper quickly, and the moisture content of the paper and paper is very large. The difference in the deformation coefficient of the base paper makes it easy for the corrugated cardboard to exhibit significant warpage. Therefore, the production speed of the machine should be based on the high moisture content of the base paper, the quality of the base paper, the preheating area and the temperature, etc., and comprehensively consider a reasonable degree. The author believes that the production speed of single-sided machine adopts slightly higher than medium speed, which effectively maintains the precision of the equipment, improves the forming hardness of corrugated board, maintains the balanced moisture of corrugated board, and reduces the warpage, collapse and slant of corrugated board. Quality problems such as sputum, foaming and degumming are practical control measures.
4. Pay attention to the detection and control of the semi-finished corrugated board of single-sided machine
Because the two-layer corrugated cardboard produced by the single-sided machine is difficult to accurately detect the edge pressure strength value, it is often only based on the touch of the hand to determine the hardness quality of the corrugated board. However, after all, the detection is only a rough, rough quality judgment, lack of science, Accurate data brings certain difficulties to the process control of the production process. To this end, the author invented the method of detecting the plane strength of the two-layer corrugated board in the inspection practice, and obtained scientific test data to facilitate the accurate analysis of the control of the single-sided machine production process. The method is as follows: firstly, a cylindrical cast iron base with a diameter of 11.7 cm is made, and the thickness is 2 cm, so that the plane compressive strength of the corrugated cardboard can be detected by using an electronic compression strength tester. Before the test, take a single tile (two layers) of corrugated cardboard and punch a number of standard specimens (area 100 cm2) with a YQ-Z-7 quantitative sampling knife. When testing, first place the cylindrical bottom plate on the lower pressure plate of the tester. After the instrument is zero-corrected, the circular sample can be placed on the cylindrical bottom for testing. When the sample is crushed, the screen is crushed. The data shown is the plane compressive strength value of the sample. The test practice shows that the flat compressive strength of corrugated board is high when the temperature, speed or adhesive of the single-sided machine is well controlled. This method is used to detect the forming hardness of corrugated board. For those cartons that are contracted to use a certain quality grade of raw paper for production, the flat compressive strength technology of two-layer semi-finished corrugated board can be developed through the detection and comparative analysis of corrugated board. Indicators, with the company's internal control quality standards, can play a better control of online semi-finished products. The semi-finished corrugated board of the single-sided machine, in addition to its flat compressive strength, should also be tested for its bond strength. The corrugated layer and the backing paper are bonded well, and the overall strength is high. Usually, the production site is generally used. “Tear-removal method” takes apart the paper and the paper, and looks at the degree of fuzzing on the paper to determine the bonding quality. The laboratory can use the electronic compression strength tester to test the bond strength of the corrugated board and obtain the test data. The basis for quality judgment. In addition, the thickness test of corrugated board is not negligible. If the corrugating roller is worn or the gap between the roller rolls is improperly adjusted, the thickness of the corrugated board will be affected, and the thickness of the corrugated board is an important indicator of the quality requirements of the customer. If it is less than the standard requirements, it will result in a batch of non-conforming products. Therefore, the production process must pay attention to the detection of the thickness of the corrugated board, and the standard thickness gauge can be used for testing to prevent the occurrence of non-conforming products.
5. Pay attention to the correct use and maintenance of single-sided machine
Corrugated roller is the core component of single-sided machine, and it is also the mold for corrugated board forming. It plays an extremely important role in the processing quality of corrugated board. Therefore, it is necessary to pay attention to the correct use and maintenance of corrugating roller. Generally, the position of the lower corrugating roller of the single-sided machine is fixed, and the upper corrugating roller applies a certain pressure to the lower corrugating roller by means of spring, air pressure or oil pressure. The lower corrugating roller is used as the driving roller, and the molars of the lower corrugating roller and the upper corrugating roller are in mesh with each other, and at the same time, the rolling surface is driven by the synchronous rotation of the upper corrugating roller. In order to ensure the even and smooth operation of the corrugating roller, the chain should not be too loose or too tight, otherwise the position of the roller should be properly adjusted. The shaping of the corrugated is achieved by a certain clamping force between the upper and lower corrugating rollers. This clamping force comes from the left and right sides of the upper corrugating roller, which is also the reason that the roller is easily deformed by the force. In order to obtain the pressure uniformly distributed along the width, the roller is required to have a convexity to compensate the pressure. Deformation. In the production process, it is necessary to prevent the abnormal pressure load of the corrugating roller from being generated to reduce the abnormal wear phenomenon. This requires that the matching pressure of the corrugating roller must be mastered, that is, the upper and lower rollers should be controlled. The gap and parallelism are important aspects of production. In addition to the correct use and adjustment of the corrugating roller, attention should also be paid to the maintenance of the corrugating roller. The bearing of the corrugated roller shaft head is prone to damage after a period of use, which will affect the normal meshing between the corrugating rollers and make the corrugating roller resistance Increase, increase the wear of mechanical parts, the quality of the corrugated board produced will also be affected, so it should be checked in time, and problems should be dealt with in a timely manner. The “tooth surface” of the corrugating roller is easy to wear during the pressing process, which makes the corrugated cardboard low and affects the strength of the carton. Therefore, it should be tested frequently, and when it is found that there is obvious wear, the reworked coating should be removed to ensure The quality of corrugated cardboard. Attention should also be paid to cleaning and cleaning the paper dust and impurities on each roller surface to prevent the foreign matter from being worn on the tooth groove of the roller; the lubrication parts should be lubricated according to the regulations to ensure the normal lubrication of the machine parts; If abnormal noise occurs, stop and check the fault in time to avoid abnormal damage caused by the diseased operation of the machine.
6. Pay attention to the control of paper quality of single-sided machine
The semi-finished paperboard produced by the single-sided machine is composed of the combination of the cardboard and the corrugated paper. If the moisture content between them is too large, the expansion and contraction of the base paper after the adhesive is absorbed and heated. Significantly increased, it is easy to cause the warpage of the cardboard, on the one hand, affecting the quality of the post-process, increasing the probability of occurrence of the non-conforming product, on the other hand, the overall strength of the carton will be significantly reduced. Therefore, before the paper roll is put on the machine, the moisture content of the base paper should be tested first, and the boxboard paper and corrugated paper with the water content close to each other should be selected as the matching molding process to prevent the corrugated cardboard from warping because the difference in the expansion rate of the base paper is too large. Deformation, reducing non-conforming products.
7. Pay attention to the control of the single-face machine glue coating mechanism
The function of the single-side machine gluing device is to apply an adhesive on the peak of the corrugated paper to bond it to the cardboard to form a single-faced corrugated board. It is mainly composed of a sizing roller, a rubber roller, a scraper, a glue tank and the like. When the single-sided machine is in normal operation, the bottom of the applicator roller is in contact with the adhesive in the glue tank and rotates at a constant speed to bring up the adhesive. The amount of glue is appropriately limited by the rubber roller, and the quantitative adhesive is applied to the peak. on. The surface of the applicator roller has a structure of fine grinding and polishing, and the surface of the roller is processed into a mesh shape, so that the glue is uniformly applied to the corrugated peak of the molding. The amount of glue applied generally requires a peak width of about 1.5 mm. The gap between the rubberizing roller and the lower corrugating roller should also be adjusted well. Generally, in the case of satisfying the coating, the gap should be as small as possible. The uniform rubber roller is used to control and adjust the amount of glue on the surface of the rubber roller. Therefore, it is important to adjust the gap between the rubber roller and the rubber roller. The gap is generally between 0.2 and 0.3 mm. The squeegee roll is also provided with a scraper, which functions to scrape off the adhesive on the surface of the smoothing roll, so that the roll surface performs the next cycle without adhesive. The function of the glue tank is to hold the adhesive and circulate the supplied adhesive so that the adhesive does not condense by heat to lower the viscosity and maintain a certain height. Usually pay attention to the use of the glue coating device, timely cleaning, paper dust, impurities, etc., which affect the viscosity of the adhesive, to ensure normal glue application and improve the bonding quality of corrugated board.
The quality control of single-sided semi-finished corrugated board involves all aspects of the production process. Correctly grasping the operation technology and correct use and maintenance of the machine is a crucial control link. This requires us to pay attention to the production process technology. At the same time, through the production process, the quality of the semi-finished corrugated board is carefully inspected and controlled, which not only can effectively prevent the quality of semi-finished board processing, but also can improve the processing quality of corrugated board and meet the processing quality of the subsequent process. The requirements lay a solid foundation for improving the quality of finished carton.