Common Causes and Improvement Measures of Tiles Producing Waste Products

The corrugated paper box industry in China has developed rapidly, but the efficiency has not increased significantly. The reason is that the increase in output value comes from the investment of large amounts of capital, equipment, and labor, rather than relying on technology to enhance benefits. For carton companies, in the face of fiercely competitive markets, improving product yields, or reducing product scrap rates, is the key to profitability.

Reducing scrap rate should be considered from the whole process of cardboard production process
The raw material input to the paperboard production line is base paper, and the output is corrugated paperboard. Therefore, the yield is the output-to-input ratio, and the ratio of all waste rejects and inputs generated between input and output is called reject rate. Having defined the concept of scrap rate, we can start with the analysis of all the process steps between input and output to analyze the cause of waste scrap and the technical measures to reduce the scrap rate.

Corrugated board production process is as follows:

Firstly, the base paper is placed on a shaftless support, and the roll is gradually laid under the premise of controlling the tension. The paper web passes through a preheating cylinder and enters a corrugating machine, and the single-faced corrugating machine is used to form a corrugated medium and fits with the paper to form a single-face corrugated paperboard. After passing through the bridge to the gluing machine for gluing, compounding the tissue paper, and entering the dryer for drying, the paperboard is pressed, slit and cross-cut as required, and finally the paper is collected by the stacker to complete the entire original paper. To corrugated board production process. Each of the above processes is closely related to the waste product rate. This article starts from each link to analyze the common causes of waste products (every phenomenon has a variety of reasons. Under the premise of assuming basic equipment adjustments, the common causes are analyzed and given Corresponding technological innovation or technological transformation program.

Tail paper waste
The waste of tail paper comes from the hexagonal taper chuck that is commonly used on the non-shaft brackets. It breaks the base paper and inner paper edges during use, making tail paper difficult to use. The tail paper scrap rate is at least More than 5%.

The use of an automatic internal-increment chuck is a relatively mature and improved solution. It has a simple structure and does not require power assistance. The chuck ribs shrink or loosen as the paper frame is moved horizontally, and automatically expand and fix the base paper in the cylinder, or automatically shrink. The removal of the base paper completely solves the disadvantages of the taper collet breaking the tail paper, and improves the utilization of the base paper, thereby reducing the reject rate.

In addition to the tail paper waste caused by the taper collapsing the edge of the paper, there is a possibility that although there is no broken edge, the tail paper is wasted because the tail paper has not been used up. Caused by artificial paper. Most of the domestic cardboard production lines do not have automatic splicing machines. It is inevitable that manual splicing is used to ensure the success of splicing. A waste of at least 50 kg will be caused by the retained paper tails, and the maximum will exceed 300 kg. A year will bring tens of thousands to hundreds of thousands of losses to the company.

Imported cardboard production lines are generally equipped with automatic splicing machines to solve this problem. It is possible to use automatic splicing to fully exhaust the tail paper. It is necessary to point out that due to the difference in the performance of the splicer, some low-grade splicers still cannot exhaust the tail paper. The reason is that the time taken for the low-level splicer to take paper is too long. If the tail paper is used, it will cause the failure of the splicing. Only the high-end high-speed splicer can completely avoid waste of the tail paper.

Waste from paper joints
Each paperboard production line will change the original paper roll at least 20 times to 50 times in each shift. If the average length of the joint is 3m~5m, the five-layer paperboard production line is used as an example. At least 400m or more, combined with the waste of the web caused by multi-ply paperboard will exceed 1000m, so the web waste caused by joints is very serious.

The use of automatic splicer can solve this problem satisfactorily, because the length of the joint of the automatic splicer is only 60mm~80mm, compared with the length of manual splicing joint 3m~5m, its waste is minimal, if the joint is not in the face paper and the bottom paper It does not even affect the normal use of corrugated board.

Change caused by tension change
The waste products caused by the change of tension when the paper web is unwound are multi-faceted. If the tension is too large, it will cause rags, shingles, bursts, paper wrinkles, flounces, and cardboard warpage. If the tension is too small, it will cause foaming. Paper web deflection, cardboard warpage and other issues, resulting in direct waste paper corrugated board, if the operator experienced the waste will be reduced, but the tension change is one of the most common reasons for cardboard directly produce waste, which accounted for The proportion is at least 10% or more.

The following situations can easily cause significant changes in the tension: when the diameter of the paper roll changes significantly during the unwinding of the web; when the machine is turned on or when it suddenly stops; when the original paper roll is replaced.

The first two cases can be solved by installing a constant tension control system. The principle is to detect the change in the output web tension (ie, the tightness of the web) in real time, and adjust the brake force of the original paper brake in real time based on the change. The feedback-brake closed-loop control loop keeps the web running at the set tension level. It should be particularly pointed out that if a very small tension level is required (which may be used when using low-grade base paper), if it is less than 0.05 MPa, only a constant tension control system is not enough, and intermediate and high-grade brakes are also required to cooperate with common pneumatics. Brake is an example. Commonly there are three kinds of disc brakes, disc brakes and multi-point brakes. The disc brakes cannot adapt to small tension control, while the plum brakes have a wide range of adaptability. No matter small tension or large tension can meet the requirements. Requirements, disk brake performance is moderate.

In the last case (that is, when replacing the paper roll), the automatic splicing machine must be combined with the constant tension control system to achieve a basically constant tension. This is because when the manual splicing is used, a constant tension cannot be achieved. At this time, the paper web is loosened. Deflection of the paper web is inevitable, and most of the paper-fed machines have a constant tension function, so that the paper-feeding function and the constant-tension function can be seamlessly combined, so that the automatic paper-feeding can keep the tension substantially constant.

Cardboard scrap caused by paper folds
As domestic companies generally use low-grade base papers to reduce costs, the waste generated from paper creases tends to increase significantly. The reason for this is that the fiber distribution and thickness of the entire width of the base paper are significantly uneven, or the fiber strength in the width direction is too low, causing the paper web to naturally contract to form a wrinkle after being subjected to a force, and therefore it is formed on the low-grade base paper. comes out often.

Although the use of high-grade base paper can avoid the occurrence of web wrinkles, it will increase the cost of paperboard and reduce the competitiveness of the product. With the innovative paper web flattening technology on the Micron Automatic Contruction Machine, even low-grade base paper will not produce web wrinkles. The paper web will have the effect of flattening to both sides when passing through each paper guide roller.

Corrugated cardboard defects caused by defects
Defects in the shape of cocoons mainly manifest themselves as high and low defects, collapses, chippings, and slanting defects. These phenomena are directly related to corrugating rollers. First, the installation and adjustment of corrugating rollers should be considered. If the upper and lower corrugating rollers are not parallel, a cardboard will appear. If the upper and lower corrugating rollers are in a wrong position, there will be high and low blemishes, broken rags and other phenomena. You can adjust the test repeatedly by loosening the adjusting block bolts on both ends of the corrugating roller; There are several technologies available for improving the wear resistance of corrugating rollers such as tungsten carbide coating technology, TC coating technology, and nano-surface treatment technology. Users can use the investment return status and fund status. Consider comprehensively to choose.

In addition, the copper knife also plays an important role in the cardboard defect of the cardboard, through which the formed corrugated paper is guided and ensured that the rubber is correctly coated under the action of centrifugal force, if the copper knife is not adjusted properly, or with the lower corrugating roller If the gap is too large, or if it is worn out, there will be irregular defects such as corrugations. The adoption of vacuum adsorption reform can completely overcome the problems caused by the copper knife. It guides the paperboard through the effect of suction and wind pressure. The uniformity is much higher than the copper knife, which can obviously improve the quality of the paperboard, but it should be improved Pay attention to sealing problems and fan power, otherwise you may not be able to achieve the expected results.
Cardboard waste caused by poor adhesion
Under the premise of structural adjustments such as the rubber roll, the poor adhesion has the closest relationship with the glue and the pressure roller. The adhesive should be guaranteed to be able to bond effectively, and the adhesive is often repetitive due to poor stability of the glue. Bad phenomena, in addition to the traditional pressure roller due to gap adjustment, wear and other reasons will also have a significant impact on poor adhesion of paperboard, converted into elastic touch bar can ensure that the corrugated paper core evenly fit on the paste roller, whether it is paper The thickness or shape change can be automatically adjusted to ensure the uniformity of the glue. Its structure is a plate-like pressure block, which has wavy grooves and is equipped with a precision spring, which can automatically adjust The beating caused by the regular pressure is to achieve the goal of uniform paste without prejudice to squash.

Cardboard waste due to unsatisfactory physical strength
According to the provisions of GB/T6544 "Corrugated Packaging Materials", the physical indicators required to detect corrugated board are: side pressure strength, burst strength and bond strength, and the physical strength of cardboard, of course, and the physical indicators of corrugated medium, such as the ring pressure index, Crack length is directly related, but the use of high-quality high-grade base paper to improve the physical strength of corrugated board is not the way the carton company expects. Therefore, the following focuses on methods and techniques for improving the physical strength of paperboard under the premise of the same corrugated base paper. .

The main factors affecting the strength of the board are: the physical strength of the corrugated medium, the forming temperature of the corrugated board, the adhesive strength, the moisture content of the board, and the hardness of the film, among which the physical strength of the corrugated medium and the forming temperature of the corrugated board are below the two factors. No longer discussed. The adhesive strength of paperboard needs to consider several factors such as the quality and process of the adhesive, the characteristics of the base paper, and the effective bonding area. The combination of corrugated paperboard mainly depends on the penetration of the starch adhesive on the surface of the paper and then diffusion and adsorption to form a surface film. Glue achieves the purpose of bonding to both surfaces of the paper, so the penetration between the glue and the paper is crucial. If the water absorption performance of the base paper is good, the tightness is moderate, and the quality of the adhesive is stable, the adhesive strength is naturally guaranteed. The high moisture content of paperboard will reduce the physical strength of the paperboard. The paperboard moisture can be reduced by controlling the concentration of glue and the amount of glue, controlling the moisture content of the paper, increasing the steam pressure, and increasing the drying capacity of the dried products. To achieve it you need to reduce