How to control and prevent the quality of corrugated board

The single-sided machine is the main equipment for the production of corrugated cartons. The quality of semi-finished corrugated board produced by single-sided machines directly affects the production cost of the cartons. The base paper is the main material for the production of cartons. The production cost of the cartons is about 75%. Raw materials, if the non-conforming or defective products of corrugated board produced by single-sided machines increase, it means waste of raw paper and other materials, increase of production costs, and decline of production profits. In the current market environment where the carton industry is generally at a meager profit, the production technology of a good one-sided machine is shut down, equipment performance and operating techniques are controlled, raw material quality is controlled, quality problems are prevented, and single-machine semi-finished products are qualified The rate is self-evident.

1. Understanding of the definition of quality standard for semi-finished corrugated board

Single-sided machine as a corrugated board molding processing equipment, is the basis for the quality of the carton product, single-sided machine production of semi-finished corrugated board quality status, nothing more than three basic characteristics, qualified products, substandard products and defective products. Qualified products means that the quality indicators of corrugated cardboard are in full compliance with the quality requirements of the relevant standards; unqualified products means that one or more specifications of corrugated paperboard do not meet the quality requirements of the relevant standards; defective products are between qualified products and unqualified products. Between the product and the quality of a defective product with minor defects, such as edge roughness, size differences, local degumming, blistering, collapse, slanting, cracking and so on. The above three standards are generally only the definition of factory internal standards. The original definition of corrugated board in the light industry industry standards is that each corrugated paperboard (three-layer structure) is classified into excellent products, first-class products, qualified products and unqualified products according to the product use and the quality grade of raw materials. Among them, excellent products are export goods and valuables packaging

Corrugated cardboard; First-class products are corrugated cardboard for domestic sales; Qualified products are corrugated cardboard for short-distance, low-cost packaging. The three types of standards also divide four standard values ​​to suit different product packaging requirements. The original national standard also stipulated that the adhesive strength of corrugated cardboard should not be lower than 588N/m; the delivery moisture of corrugated cardboard (according to online moisture) should be 14±2%; the appearance and quality requirements of corrugated cardboard should be smooth, clean and not allowed. There are no materials, thin edges, trimming edges should be neat, and the adhesion is firm. The sum of the degumming parts should not exceed 20cm2 per square meter. Defective products refer to products that are judged as unqualified by the sampling rules. Practice shows that some quality indicators of superior products are unqualified and may become first-class products or qualified products. Some quality indicators of first-grade goods are unqualified and may become qualified products. However, the single corrugated cardboard referred to by the National Standard is a corrugated cardboard formed by bonding two layers of cardboard and corrugated corrugated base paper. The two-layer corrugated paperboard produced by a single-machine single-unit unit has not been coated, and its bursting strength and edge pressure strength will be greatly reduced. Therefore, the national standard for corrugated paperboard cannot be applied, and so far our country has not been single-sided. The standards of semi-finished corrugated board and the general system of more standard enterprises adopt self-developed corporate standards to control the semi-finished corrugated board in the production process. However, the company standards are not necessarily detailed, complete and accurate. In practice, It is necessary to pay attention to continuous analysis and summary in order to carry out appropriate revision and improvement so that the standard can play a good role in promoting the standardization of production processes and operating techniques.

2. The effect of poor quality of semi-finished single-sided machine on post-processing production

After the production of single-fabricated semi-manufactured paperboards with single-sided machines, the preprinted paperboard face-sheets and the two-layer single-corrugated paperboards are also affixed by a cladding machine to form a three-layer single-wall corrugated paperboard, which can then be processed by die-cutting. Carton finished product. From the characteristics of the post-processing production process of the carton, it can be seen that maintaining the flatness of the corrugated paperboard plays an important role in ensuring the quality of the paperboard and the precision of die-cutting. If the semi-finished corrugated board produced by the single-sided machine is warped and deformed, it will affect the normal positioning of the automatic feeding machine and the corrugated board. Some corrugated board is curled and deformed more severely. The operator of the cover machine has to deform the warpage. The corrugated board is kneaded in the opposite direction, so that it maintains the flatness required for automatic paper feeding. However, after the corrugated board is broken and collapsed, the compressive strength of the formed carton will be greatly reduced. If the single-sided machine's corrugated board is severely warped, the three-layer corrugated cardboard will be prone to warp warpage after being applied by hand-operated veneers. When semi-finished products are die-cut to the die-cutting machine, they will also be given The normal feeding and positioning cause some obstacles and affect the molding quality of the carton. Therefore, in the production process of single-sided machines, we must pay attention to controlling 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 of quality problems in semi-finished products

The production process shows that the quality of the corrugated board produced by a single-sided machine is good, and the qualified rate of the quality of the carton has a reliable guarantee. The author found in the quality tracking management that sometimes raw materials are qualified, but due to the improper control of the production process technology and operation technology of the single-sided machine, for example, in order to catch up with the production speed, it is easy for the cardboard to be heated for a short time and the corrugation peak Insufficient gluing results in a reduction in the molding hardness of the paperboard, and the problem of decreased adhesive strength tends to occur. It is worth mentioning that if one-sided machines with incomplete auxiliary facilities are used at too fast speeds, it is difficult for the machine to quickly adjust the moisture of the base paper in a balanced manner. In the case where the moisture content of the paper and liner papers is very different, The difference in the coefficient of deformation of the base paper makes it very easy for the corrugated board to show significant warpage. Therefore, the production speed of the machine should be based on the conditions of the moisture content of the base paper, the quality of the base paper, the preheating area and the temperature, etc., and comprehensive consideration should be taken to reasonably grasp a suitable degree. The author believes that the production speed of the single-sided machine is slightly higher than the medium speed, which effectively maintains the precision of the equipment, improves the forming hardness of the corrugated board, maintains the balanced moisture in the corrugated board, and reduces the warpage, collapse, and skew of the corrugated board. Quality problems such as defects, foaming, and degumming are practical control measures.

4. Should pay attention to the detection and control of semi-finished corrugated cardboard

Because single-sided machine production of two-story corrugated board is difficult to accurately detect the side pressure strength value, often just touch to determine the hardness of the corrugated board molding quality, but this test is only a rough, rough quality judgment, lack of science, Accurate data brings certain difficulties to the process control of the production process. For this reason, in the inspection practice, the author invented the detection method of the plane strength of the two-layer corrugated cardboard, and obtained scientific test data to facilitate the accurate analysis of the control of the single-sided machine production process. The practice is: first to make a cylindrical cast iron bottom bracket with a diameter of 11.7cm, with a thickness specification of 2cm, so that the flat compressive strength of the corrugated cardboard can be detected with an electronic compressive strength tester. Before testing, take a single tile (two layers) of corrugated cardboard and punch a number of standard specimens (100 cm2 in area) with a YQ-Z-7 quantitative sampling knife. During the test, the cylindrical bottom bracket shall be placed on the lower pressure plate of the tester. After the zero adjustment and correction of the instrument are performed, the circular sample can be placed on the cylindrical bottom bracket for testing. When the sample is pressed, the screen is pressed. The data shown is the plane compressive strength value of the sample. Inspection practice shows that when the temperature, speed or adhesive of a single-sided machine is controlled well, the flat compressive strength of corrugated cardboard is high. This method is used to detect the forming hardness of corrugated board. For those cartons that are contractually designated for production using a certain quality grade of base paper, the flat compressive strength technology of two-layer semi-finished corrugated cardboard can be developed through the detection and comparison analysis of corrugated cardboard. Indicators, with the company's internal control quality standards, can play a better role in controlling semi-finished online products. The semi-finished corrugated cardboard with single-sided machine, in addition to its flat compressive strength, should also be tested for its adhesive strength. The corrugated layer is well bonded to the liner, and its overall strength is high. Usually, the production site is generally used. “Tear-off method” disassembles the paper and the paper to determine the bonding quality. The laboratory can use the electronic compressive strength tester to test the adhesive strength of the corrugated cardboard and obtain the test data. Quality judgment basis. In addition, the thickness inspection of corrugated board is not negligible. If the corrugating roller is worn or the gap between the two rolls is not properly adjusted, the thickness of the corrugated board will be affected. The thickness of the corrugated board is an important indicator of the customer's quality requirements. Once the thickness of the corrugated board reaches Less than the standard requirements, will result in batches of non-conforming products, therefore, the production process must pay attention to the detection of the thickness of corrugated board, a standard thickness meter can be used to detect, in order to prevent the production of non-conforming products.

5. Pay attention to the correct use and maintenance of single-sided machines

Corrugated roller is the core part of single-sided machine, and it is also the mold for corrugated paperboard. It plays an extremely important role in the processing quality of corrugated board. Therefore, we must 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 corrugated roller acts as a driving roller, and the squeaking tooth and the upper corrugating roller mesh with each other through the squeegee, and simultaneously the upper corrugating roller is driven by the roller surface to realize the pressure sagger forming. In order to ensure the smooth and even operation of the corrugating roller, the chain must not be loose or tight. Otherwise, the position of the roller should be properly adjusted. The corrugated shape is achieved by a certain clamping force between upper and lower corrugating rollers. This clamping force comes from the upper and lower sides of the upper corrugated roll. This is also the reason that the roll is easily distorted and deformed. In order to obtain a uniform distribution of the pressure along the width, the roll is required to have a convexity to compensate for 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 must be controlled properly. The gap and parallelism are important parts 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 corrugating roller shaft head is prone to damage after a period of time, which will affect the normal meshing between the corrugating rollers and make the running corrugating roller resistant. Increase, aggravate the wear of the mechanical components, the quality of the corrugated board produced will also be affected, so usually should be checked in due course, find problems and deal with it in time. Corrugated roller “tooth surface” is easy to wear during the pressing process, which causes the cardboard corrugation to become low and affects the strength of the carton. Therefore, it should be checked frequently and found that when there is obvious wear, the reworked coating should be removed to ensure Corrugated board quality. It is also necessary to pay attention to the cleaning and cleaning of paper dust and impurities on each roll surface to prevent the foreign material from wearing on the tooth groove of the roll. Each lubrication area must be lubricated in strict accordance with regulations to ensure normal lubrication of the machine parts; during mechanical operation If abnormal noise occurs, stop the machine in time to check and troubleshoot the machine to prevent the machine from operating abnormally.

6. Should pay attention to the control of the quality of single-sided machine

The semi-finished paperboard produced by a single-sided machine is composed of cardboard and corrugated paper. If the moisture content between them is too great, then the base paper will absorb adhesive and heat, and the original paper will change its expansion and contraction. Obviously increased, it is very easy to cause cardboard warpage, on the one hand affect the quality of post-processing stickers, increase the probability of non-conforming products, on the other hand will make the overall strength of the carton significantly reduced. Therefore, before the paper roll is on the machine, the moisture content of the base paper should be tested first, and as far as possible, the liner and corrugated paper with the moisture content close to each other should be selected for forming so as to prevent the warpage of the corrugated paperboard from being caused by the large difference of the base paper's expansion ratio. Deformation phenomenon, reduce defective products.

7. Pay attention to the control of the single-sided machine gluing mechanism

The function of the single-sided machine gluing device is to apply an adhesive on the corrugated paper ridge to bind it with the cardboard paper to form a single-faced corrugated cardboard. It is mainly composed of a sizing roll, a squeegee roll, a scraper, and a glue tank. When the single-side machine is in normal operation, the bottom of the squeegee roller contacts 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 squeegee roller, and the quantitative adhesive is applied to the peak. on. The surface of the squeegee roll has a structure that is ground and polished, and the surface of the roll is processed into a mesh pattern so that the glue is evenly applied to the formed corrugation peak. The amount of glue applied generally requires a peak width of about 1.5mm. The gap between the sizing roller and the lower corrugating roller should also be adjusted properly. Generally, in the case where the gluing is satisfied, the gap should be as small as possible. The squeegee roller is used to control and adjust the amount of rubber on the roller surface of the rubberizing 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 roller is also equipped with a squeegee, which functions to scrape off the adhesive on the surface of the squeegee roller, so that the roller 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 become hot to coagulate and reduce the viscosity and maintain a certain height. It is necessary to pay attention to the use of glueing equipment in a timely manner, timely cleaning, will affect the viscosity of the paper dust, impurities, etc. to clean, to ensure the normal coating, improve the quality of corrugated board adhesion.

The quality control of semi-manufactured corrugated cardboard with single-sided machines involves all aspects of the production process. Correctly grasping the operation process technology and using and maintaining the machine correctly are crucial control steps. This requires us to pay attention to the production process technology at ordinary times. The quality control of the semi-finished corrugated board through careful inspection and control of the quality of the semi-finished corrugated board can not only effectively prevent the occurrence of semi-finished board processing quality problems, but also improve the processing quality of the corrugated board better, and satisfy the processing quality of the subsequent processes. The request lays a solid foundation for improving the quality of finished cartons.