Kraft paper production technology

I don't know if you need corrugated surface kraft paper or pure kraft paper. The following is the manufacturing process of corrugated paper.

You can check the information you want on China Printing Network and China Packaging Network.

Chapter I Composition of Corrugated Board

Corrugated board began at the end of 18, and its application increased significantly at the beginning of 19 because of its light weight, low price, wide use, simple manufacture and recycling. By the beginning of the 20th century, it had been popularized and applied to the packaging of various commodities. Because the packaging container made of corrugated board has its unique performance and advantages in beautifying and protecting the internal goods, it has achieved great success in the competition with various packaging materials. It has become one of the main materials for making packaging containers, and it has a long history of use and has developed to this day.

Corrugated board is made of face paper, inner paper, core paper and corrugated paper by bonding. According to the requirements of commodity packaging, corrugated board can be processed into single-sided corrugated board, three-layer corrugated board, five-layer, seven-layer corrugated board and eleven-layer corrugated board (as shown in figure 1, figure 2 and figure 3). Single-sided corrugated cardboard is generally used as a protective lining for commodity packaging or to make light trucks and cushions to protect commodities from vibration or collision during storage and transportation. Three-layer and five-layer corrugated boards are often used to make corrugated boxes. Many goods are packed with three or five layers of corrugated cardboard. On the contrary, they are exquisite. Printing color graphics and pictures on the surface of corrugated boxes or corrugated boxes not only protects internal goods, but also publicizes and beautifies internal goods. At present, many corrugated boxes or corrugated boxes made of three-layer or five-layer corrugated boards have been directly placed on the sales counter and become sales packaging. Seven-layer or eleven-layer corrugated cardboard is mainly used to make packaging boxes for electromechanical, flue-cured tobacco, furniture, motorcycles and large household appliances. In some commodities, corrugated cardboard can be combined into inner and outer boxes, which is convenient for manufacturing, storage and transportation of goods. In recent years, according to the needs of environmental protection and the requirements of relevant national policies, the commodity packaging made of this corrugated board has a trend of gradually replacing wooden box packaging.

The first section corrugated board stare blankly and waveform.

1. Corrugated board with a dull shape

Corrugated boards with different corrugated shapes have different functions. Even if the same quality of face paper and inner paper are used, the performance of corrugated board is different because of the different shapes. At present, there are four kinds of corrugated grooves commonly used in the world, namely, A-type groove, C-type groove, B-type groove and E-type groove. See table 1 for their technical indicators and requirements. Corrugated board made of A-type corrugated board has good cushioning and certain elasticity, while C-type corrugated board is superior to A-type corrugated board made of cold porcelain. But the stiffness and impact resistance are better than that of A-beam. The density of B-shaped ribs is high, and the corrugated board made of B-shaped ribs has a flat surface and high pressure, which is suitable for printing. E-beam is thin and dense, which shows its rigidity and strength.

Table 1

Leng height, mm leng number, each /300mm.

A 4.5~5 34 2

C 3.5~4 38 2

B 2.5~3 50 2

E 1. 1~2 96 4

Second, the corrugated wave shape.

Corrugated paper that constitutes corrugated board is divided into V-type, U-type and UV-type.

V-shaped corrugated waveform is characterized by high plane pressure resistance, saving adhesive consumption and corrugated base paper in use. However, the corrugated board made of this waveform has poor cushioning and is not easy to recover after being pressed or impacted.

U-shaped ripple waveform is characterized by large gluing area, firm bonding and certain elasticity. When impacted by external force, it is not as fragile as V-shaped stare blankly, but the plane expansion pressure intensity is not as good as V-shaped stare blankly.

According to the characteristics of V-corrugated and U-corrugated, UV-corrugated roller has been widely used. The processed corrugated paper not only maintains the high pressure resistance of V-shaped corrugated paper, but also has the characteristics of high adhesive strength and certain elasticity of U-shaped corrugated paper. At present, the corrugated roller of corrugated board production line at home and abroad adopts this kind of UV corrugated roller.

Section II Corrugated Board Manufacturing

At present, there are generally three kinds of equipment for producing corrugated board and corrugated box in China. One is the traditional stand-alone machine. It is a corrugated paper machine that makes corrugated base paper into waves. It is a kind of sizing machine that bonds face paper, inner paper, core paper and corrugated paper together to complete the manufacturing process of corrugated board. The equipment for manufacturing corrugated boxes and corrugated boards with a single machine also needs to complete batching, cutting, printing, splicing, cutting, grooving, chamfering and molding. The whole single machine assembly line has many equipments and process links, and the product quality is difficult to control and the consumption is high.

The other is a single-sided corrugated paper machine, which first produces single-sided corrugated paper boards and then processes them with a single rubber truck to produce corrugated paper boards with different structures and structures.

The production process and equipment structure of single-sided corrugated paper machine are shown in the figure (Figure 4).

Fig. 4 structural schematic diagram of single-sided corrugated paper machine

Single-sided corrugating machine is a semi-automatic production line consisting of roller support, single-sided corrugating machine and rotary support paper cutter. It has the characteristics of high efficiency, good product quality and strong adaptability.

The other is to use the automatic continuous production line of corrugated board to complete it. All kinds of equipment organically combine the whole corrugated board production process to make it produce continuously. The traditional method of multi-machine combined production not only has high production efficiency and low labor intensity, but also has centralized control, simplicity and safety, and low noise. The most important thing is that the corrugated board produced is of high quality. Cold shape and waveform shape are standardized, reasonable and standardized. A piece of paper produced by this equipment, diamond cut diamond, makes the packaging container neat, beautiful and smooth. Appearance and physical properties are better than those produced by single machine or combined single machine linkage line.

Schematic diagram of production technology and equipment structure of five-layer corrugated board production line (as shown in Figure 5).

This paper briefly introduces the concrete construction technology and technology of these three kinds of processing equipment.

I. Multiple independent combined systems

1, cutting equipment

Single machine multi-puffing dispersion operation, in order to make the web or flat paper suitable for the size and specification of post-processing, it needs to be cut. In order to save raw materials and maximize the utilization rate of paper,

It is also necessary to plan materials and implement standard splicing.

The web is cut by a single-blade rotary paper cutter (as shown in Figure 6). The equipment consists of paper feeding rack, paper drawing, paper feeding, longitudinal cutting, transverse cutting and material receiving. You can also trim and calculate cuts. Cutting specifications can be adjusted according to processing requirements.

The paper cutter cuts the flat paper (as shown in Figure 7). The equipment consists of paper cutting system, pressure system and high-speed specification system. At present, the advanced paper cutter adopts numerical control device, hydraulic control and light guide elements, which ensures the cutting accuracy, improves the working efficiency and runs safely and reliably. The machining specification is determined by the forward and backward movement of the special pusher.

2. Corrugating machine

The corrugating machine presses the cut or spliced corrugated base paper into corrugated paper (as shown in Figure 8). The equipment is mainly composed of upper and lower corrugated rollers, heating device, adjusting system, anti-roll paper guide claw and so on. In order to form and fix the corrugated roll well, the surface temperature of the corrugated roll must be kept at about 200℃. At present, most heating devices used are quartz tubes, and heating wires or heating wires are wound on long, square or round heat-resistant bodies. There are also silicon carbon rods for heating. The power consumption of the whole machine is 10KW/H when the heating wire is heated, and 20KW/H when the silicon carbon rod is heated. Compared with the former, the latter has the advantages of faster heating, lasting surface heating and long service life, but it consumes more power. The corrugating rollers used in the corrugating machine are type A, type C and type B. The E-type corrugating machine is a special equipment for manufacturing corrugated boxes. It is small in size, and the diameter of the corrugating roller is about150 mm. In order to save energy, the equipment manufacturer has set up an insulation layer on the surface of the corrugating machine to cover the corrugating roller, which not only maintains the thermal efficiency, but also ensures the safety. Some ingredients manufacturers adopt high technology and install temperature control devices to ensure the plasticity of corrugated and save energy.

3, glue machine

The rubber stripper is mainly composed of a pair of coating rollers, two rubber scraping rollers, a rubber storage tank and a pressure regulating system (as shown in Figure 9). Its function is to evenly and properly coat a layer of adhesive film on both sides of corrugated paper. Then the operator aligns the corrugated tile paper coated with glue between the inner paper and the surface paper to make corrugated board. After a short time (1-4 hours) of pressing and natural drying, the corrugated board can be processed in the next process. The surface of coating roller and scraper roller of glue coater with high equipment precision is chrome plated, which is resistant to acid and alkali corrosion and wear. The glue storage tank can be lifted automatically, which is convenient for cleaning after changing different glue.

Many small enterprises that produce main paper packaging containers mostly use this harmonious structure technology to produce corrugated board. In order to save manpower and material resources and improve production efficiency, some enterprises arrange the gluer of the corrugating machine into an L-shape, and combine it by belt reversing in the middle, or by the action of smooth tube, the belt with corrugated lines instantly attracts the electromagnetic clutch, so that the corrugated paper falls on the belt sent to the gluer, and the continuous operation effect is good.

Second, single-sided machine and corrugated board production line

Single-sided machine is a mechanical equipment that presses corrugated paper into corrugated paper, coats adhesive on it, directly adheres to thin paper, and instantly gelatinizes it by heating, thus manufacturing single-sided corrugated board that meets the quality requirements. Its production process flow (Figure 4) has been marked. The equipment is mainly composed of base paper frame, corrugated roller, pressure roller, preheating roller, gluing system, glue storage and circulation system, heating system, pneumatic components and cutting part. The functions of each part are briefly described as follows:

1, base paper rack

The base paper rack used by the single-sided machine is relatively simple, mainly because the machine moves up and down and manually adjusts the tension of the paper web, which has a certain bearing capacity, also called shaft support (as shown in figure 10).

2. Corrugating roller

The corrugated base paper is pressed into corrugated paper by the combination of upper and lower corrugated rollers. The matching pressure (gap), parallelism and suitable middle height of corrugated roller are important technical indexes when corrugated roller works.

3. Pressing roller

Apply pressure (0.4-0.5MPa) to the tissue paper and corrugated paper coated with glue to make them firmly stick together to form single-sided corrugated paper.

4. Preheating roller

In order to ensure that corrugated paper has a good appearance and good adhesion of single-sided corrugated paper, preheating rollers are used to dry the drum base paper to maintain a certain moisture.

5. Glue coating system

The main function is to coat a uniform film on the surface of the pressed ripple peak. The system consists of coating roller, glue tank, squeegee and glue circulation device. The working quality of gluing system directly affects the bonding strength of corrugated board. In order to ensure the uniformity of the film during the operation of the equipment, the gap between the scraping roller and the coating roller is required to be 0.3-0.45 mm.

6. Heating system

Mainly heating corrugated roller, pressure roller, preheating roller and other parts. At present, there are steam heating, liquefied gas heating, oil heating and electric heating. No matter which heating method, the surface temperature should be kept at about 170℃. When using steam to add tears to eyes, considering the reduction of thermal efficiency and uneven surface temperature caused by condensed water stored in the container, a siphon device must be set up. The gap between the suction port of siphon device and the inner wall of corrugated roller should not be greater than 0.8mm or less than 0.3mm, so as to facilitate the timely discharge of condensed water.

7. Pneumatic device

Some single-sided machines use manual devices in the adjustment of corrugated rollers and pressure rollers, which is easy to cause unnecessary wear due to improper adjustment of equipment use rights, or can not guarantee the quality of single-sided corrugated board. Pneumatic device is used to adjust the gap between corrugated roller and pressure roller on single-sided machine on automatic line. In order to ensure that the pneumatic device system always works in a good state, it is necessary to ensure that the air compressor works normally, the working pressure of each pneumatic element is 0.4MPa, and the quality of each sealing material in the pneumatic element is reliable.

8. Paper guide plate and vacuum adsorption device

The core component of the single-sided machine is the upper and lower corrugated rollers. As mentioned above, the parallelism of the upper and lower corrugating rollers and the pressure roller and the reasonable gap between them are very important. In addition, because the corrugated base paper passes through the corrugated roller, the corrugated base paper will be separated from the corrugated roller due to the centrifugal effect of the high-speed operation of the corrugated roller. In order to keep the corrugated paper from being thrown out and keep a good fit with the corrugated roller, it is necessary to complete it through the vacuum adsorption device of the paper guide plate.

At present, in most corrugated board production equipment, it is the guide board that allows corrugated base paper to enter the corrugated roller, forming the right to use corrugated paper. The installation position of the guide plate must be correct, which plays a very important role in the quality of corrugated board. As a component, the paper guide plate is installed on the cross beam, and the distance between the paper guide plate and the paper guide plate must be consistent with the paper guide groove on the upper corrugated roller and the coating roller. The gap between the A-type paper guide and the lower corrugated roller is 0.5mm, the C-type paper guide is 0.45mm, and the B-type paper guide is 0.4mm. Improper adjustment of the gap will cause the corrugated paper to be squeezed and rubbed, which will seriously affect the quality of corrugated paper, so it should be carefully adjusted.

A few days ago, the more advanced corrugated board production line used the vacuum adsorption principle to attach the corrugated base paper to the lower corrugated roller, and completely absorbed the corrugated base paper on the lower corrugated roller, so that the corrugated peaks were evenly coated with glue, ensuring the quality of corrugated board (Figure 1 1).

9. Cutting device

The bonded single-sided corrugated board is cut according to certain specifications according to the processing requirements. It is mainly made up of longitudinal circular knives and transverse knives, and it is actually an independent rotary paper cutter.

There are two kinds of base paper racks in automatic corrugated board production line: rotary and hydraulic (as shown in figure 12 and figure 13). The latter is more advanced and does not need to set a basin on the ground. The paper clamping part is electrically controlled, and the placing motion is converted into linear motion. The power comes from the reduction motor fixed on the paper clamping arm. According to the setting of linear force, a torque limiting device is installed at the output shaft end of the motor. Its base paper lifting part is driven by two groups of hydraulic systems, which is safe and reliable. The rotating shaftless bracket is controlled by electricity, one part controls the forward rotation or reverse rotation of the clamping arm, the other part controls the left and right clamping and loosening of the base paper, and the manual braking device controls the tension of the roll paper. In order to meet the needs of its work, it is necessary to dig a basin with enough space to make its clamping arm swing on the ground with rotating shaftless support.

No matter what kind of base paper rack, its function is not only to load and release the roll paper, but also to brake. Due to proper braking control, the web will maintain proper tension during operation, so as to ensure that the produced corrugated paperboard and core paper will not wrinkle, and the corrugated will be flat and flat, and there will be no collapse, breakage, skew and other phenomena.

The main functions of the base paper rack in the automatic production line of one-stop paperboard are loading paper, putting paper, moderately clamping paper, correcting deviation, braking and turning over.

In the automatic production line of corrugated board, the setting of preheater is very important. The combination of face paper, corrugated base paper and single-sided corrugated board should be preheated separately before entering the gluing device, so as to make them adhere well and maintain proper and uniform moisture. The preheater can be adjusted and rotated at will to ensure a good working condition, maintain the amplitude tension of base paper and single-sided corrugated board, and achieve a good use effect. The preheating angle of the paper web is not less than 90 degrees (as shown in Figure 14).

In order to ensure the preheating of single-sided corrugated board with different layers, there are triple and quintuple heaters.

In order to make the single-sided corrugated board transfer evenly and orderly, it is necessary to set up a paper overpass. Let the single-sided corrugated board run according to the specified track under control, and then combine it. The paper-passing overpass is mainly composed of rectification part, transmission part, tension adjustment and control device, etc. It makes the single-sided corrugated board pile up in order, which can make the moisture of the single-sided corrugated board evaporate and solidify properly and enhance the bonding strength. At the same time, when the single-sided machine stops for some reason, proper accumulation will not affect the production and operation of subsequent processes.

Glue coater is a device that coats single-sided corrugated board or multi-sided corrugated board with adhesive to form three or more layers of corrugated board. According to the processing structure of corrugated board, the sizing machine is divided into single-layer (for three-layer corrugated board), double-layer (for five-layer corrugated board), three-layer (for seven-layer corrugated board) and other sizing mechanisms. The gluing device is mainly composed of preheating roller, gluing roller, floating roller, pressure roller, paper guide roller, heat insulation plate, pneumatic components, glue storage tank and other parts (as shown in Figure 15).

In order to keep the glue applicator running synchronously, its transmission is driven by a double-sided machine. When the coater rotates at no load, the independent motor runs through the reducer.

The function of glue applicator is to apply glue evenly on the wave crest of single-sided corrugated board. The coating roller is provided with specially processed reticular pyramid pits, which can save glue consumption and spread glue evenly. In order to ensure better bonding quality, the working pressure of the floating pressure roller controlled by pneumatic components should be not less than 0.5MPa, and the coating roller and the scraping roller should have good parallelism, and the working gap between them should be 0.25-0.4 mm

When three, five, seven or more layers of corrugated cardboard are combined together, they enter the drying, setting and cooling system. The system is a duplex part. The duplex machine consists of a hot section and a cold section. The main function is to make the moisture in corrugated board fully evaporate, so that the adhesive can be cured and wrinkled. The heating section consists of several groups of hot furnaces side by side, and the surface of the machine is smooth and flat. Corrugated board is directly attached to it, and a special canvas belt with good air permeability, certain tension and gravity and a driving press roller are added to the upper end face of corrugated board, so that the corrugated board is heated and dried under a certain pressure during operation. The heating section is divided into high temperature zone and low temperature zone. The high temperature zone gelatinizes and dries the adhesive, which enhances the bonding force. The low temperature zone makes the corrugated board dry and stable. The function of cooling section is to disperse excess heat, even moisture and avoid warping, so that corrugated board can smoothly enter the next process.

In order to ensure the normal operation of the double-sided machine and make the tension of the canvas belt suitable during operation, it is necessary to adjust the pneumatic or manual tensioning mechanism or control device in time. Canvas belts should be kept clean and dry at ordinary times to facilitate good ventilation. The use of pressure roller should be adjusted in time according to the forming situation of corrugated board, the speed of automatic production line and the quality of various webs to ensure the quality of corrugated board.

The cutting part is mainly composed of the transverse cutting machine of the longitudinal creasing machine. The function of cutting the indentation part is to cut the corrugated board into a certain width according to the production needs, and complete the indentation required for the longitudinal bending of the corrugated board at one time during the longitudinal cutting. The slitting machine is usually a two-part slitting and creasing machine. Two sets of required specifications can be adjusted at the same time according to production requirements. When changing the production specifications, only the electrical control device needs to be started, so that the equipment can be put into use by rotating180, which reduces the downtime, reduces the consumption and improves the production efficiency. In order to ensure that the cutting knives do not make the inner and inner layers of corrugated board meet the national standards when cutting, the adjusted fit clearance of each group of knives should be less than 0.04 mm.

The slitting and creasing machine itself has an adjusting mechanism for the upper and lower gap between the slitting knife and the creasing wheel, which should be adjusted in time according to the different thickness of corrugated board. Ensure the quality of cutting and indentation.

After research and discussion by many packaging technicians, the single-point indentation wheel developed by Comrade Song Shibin of Xi 'an Qinchuan Mechanical Carton Factory is popular now (as shown in Figure 16).

The characteristics of the five-point indentation wheel are: the center line is prominent, the indentation size is accurate, and the groove width is 6.4mm, which makes the corrugated board fully deformed; The two shoulders are inclined planes, which makes the corrugated board damaged well in the rolling process and the stress is not concentrated; Make the corrugated board deform naturally and form unbroken marks.

The transverse cutting machine mainly completes the transverse cutting of corrugated board according to certain specifications. It consists of an upper roller and a lower roller which can rotate and are equipped with a long knife, and a group of devices which can perform instantaneous shearing when rotating to a certain angle. Double-roller rotation with long knives is equipped with adjustable gapless gear matching transmission to ensure shearing accuracy. When the gear is worn, the gear clearance can be readjusted. The use of transverse cutting machine should ensure the use and adjustment of CVT, because the change of speed ratio is related to the coal cutting length of corrugated board. In the process of operation, the tension of corrugated board should be controlled according to the quality of corrugated board, so as to prevent the thickness of corrugated board from being affected by the weight of driving roller and certain tension.

The key to the use of transverse cutting machine is the installation and adjustment of blade. The installation of two long knives of the transverse cutting machine is fixed on the main shaft with pressure plates and bolts. The adjustment of blades is mainly to adjust the joint clearance between two blades when the cutter shaft rotates. The best fit clearance should be 0.05 mm, so that when the cutter shaft rotates, it will not produce the biting impact of the blade, and at the same time, it will rotate briskly, and the edge of the cut corrugated board will be smooth and tidy, and the blade will meet the requirements of national standards.

Section III Corrugated Board Printing and Post-processing Technology

Whether using a single laminating machine or a more advanced laminating machine, making corrugated cardboard into corrugated boxes with different specifications is nothing more than printing, pressing lines, slotting, cutting corners and bonding. It can also be printed, die-cut and glued.

Before the corrugated board is formed, the printing surface has been directly adhered to the corrugated board with glue wizard. Therefore, the forming process of corrugated box can be completed only by slitting machine, line pressing machine, angle cutting machine and box punching machine. Since 1980s, in the process of single machine production, in order to ensure the overall quality of corrugated boxes, improve production efficiency and reduce consumption; A combined device with comprehensive cutting, line pressing, grooving and corner cutting functions is used (as shown in Figure 17). Single-machine production equipment such as cutting, line pressing and angle cutting has been gradually eliminated.

Single-sided corrugated made by single-sided machine must be produced by single machine and combined production to complete the molding process. However, unlike a single combined machine, the corrugated board produced by a single combined machine and completely recovered by a single combined machine can be formed before nailing the box, or can be completed by a corrugated board printing machine, a corrugated board printing slotting machine, a corrugated board printing die-cutting machine and other units.

The only equipment that supports the automatic corrugated board production line to complete the molding process is a large printing slotting unit or a printing die cutting unit.

Briefly introduce these two devices:

I. Printing slotting device

The equipment consists of feeding, printing (once, twice or many times), slotting, indentation, chamfering, cutting, waste extraction and accumulation. The equipment structure is schematic (as shown in figure 18).

Now, the structure of the printing slotting unit will be explained item by item.

1, feed section

This part consists of paper scraping roller, paper feeding roller and vacuum adsorption. Mainly to send corrugated board to the printing system smoothly and accurately.

2. Printing part

This part consists of aniline ink circulation system, ink mixing cots, anilox rollers, printing plate rollers and gap adjusters of each part. The working state of the gap adjuster is completed by pneumatic components, electrical components and mechanical actions respectively.

At present, the printing equipment used by corrugated box manufacturers has different structures because of the different ink-free performance. The corrugated board printing machine using ink-free ink can not only print corrugated board, but also print general cardboard. Its inking system is more complicated than aniline printing machine. The printed pattern characters are close to the offset press. The equipment using aniline ink for printing is characterized by using aniline ink with low viscosity, so the transfer structure of printing machine ink is very simple.

Printing corrugated board with aniline ink is easy to output ink to the surface of corrugated board, which not only has low damage rate, but also has high quality of printed patterns and characters. Using this printing equipment, in the process of high-speed printing, the evaporation of water will cause the change of aniline ink concentration, so it is necessary to adjust the printing tone by constantly adjusting the viscosity of the ink.

The printing plates used by printing slotting unit mainly include rubber plate and resin plate. Rubber plate can only be used as an ordinary printing plate because it is carved by hand. And fine pattern text, it is necessary to use resin plate to print.

3. Line pressing, slotting, corner cutting and cutting.

This part mainly consists of upper and lower rollers, upper and lower grooving knives, upper and lower chamfering knives and longitudinal cutting knives. The upper and lower rollers mainly complete the longitudinal pressing of corrugated board, and the upper and lower grooving knives cut into the lower concave knives through the upper convex knives to complete the grooving of corrugated board; The upper chamfering cutter and the lower chamfering cutter complete the tenon molding at the joint of the corrugated box through the upper chamfering blade and the lower chamfering cutter pad, and trim and trim the edges according to the specified size.

Between printing and printing, line pressing and slotting of multi-color printing unit, polyester and lower wheel with mesh surface are installed as transmission devices, so that corrugated board can pass through each working procedure synchronously and accurately.

4, pumping waste and accumulation.

The main function of this part is to extract and crush the paper scraps produced by reverse grooving, corner cutting and cutting through the pipeline, so as to maintain the working environment on site. In the stacking part, the printed products are taken out by the conveyor belt, and then the corrugated boards that have undergone the printing and slotting processes are stacked on the discharge rack by the conveyor platen that can be adjusted up and down, and then enter the next process.

5, nail box combination part

The combination part mainly includes two ways: nailing and bonding. In recent years, automatic and semi-automatic boxing machines have been developed in China, in addition to the traditional single boxing machine to complete the forming of combined corrugated boxes. According to the arrangement of box nails, the nail head structure of box nailing equipment can be divided into single oblique nail, double oblique nail, single straight nail, double straight nail, single horizontal nail and double horizontal nail. At present, double diagonal nails are widely used because their arrangement structure enhances the bonding strength of corrugated boxes. The box nails used for nail box are coated low carbon steel flat wires. Specifications are divided into 16#, 18# and 20#. The combination of corrugated paper should use 20# box nail flat wire.

Many commodities use corrugated boxes and corrugated boxes, because they are directly packaged in the technological process of commodity saliva production, so paste combination must be used. Some commodity packages have to use paste combination because of the requirements for the goods they contain. In recent years, China has developed and produced a semi-automatic or full-automatic box pasting machine (as shown in Figure 19). Most adhesives used for bonding are polyvinyl acetate emulsion, polyvinyl chloride solution, animal glue and starch glue.

Automatic box pasting machine is a high-tech product successfully developed in China. It is mainly composed of paper feeding system, gluing system, folding and forming rectification system, counting, accumulation and output system. High-precision timing control integrating light, electricity and gas. High efficiency and high automation ensure the high quality combination of corrugated boxes.

Second, the printing die-cutting machine group

The printing part of the printing die-cutting machine group and the printing part of the printing slotting machine group are basically the same in function and technology, and will not be described here.

The die-cutting equipment used in a single combined equipment is mostly flat press and Chen-style flat die-cutting machine. Flat die cutting machine is mostly used for corrugated paper laminating and paperboard laminating; Chen's flat die-cutting machine can directly process corrugated board to make corrugated boxes and corrugated boards. However, because of its slow speed and low production efficiency, it can not be directly combined with printing equipment to form continuous production, so it is only used as a single machine.

In recent years, the circular indentation tangent machine has been developed, and the application effect is good. The die-cutting equipment combined with the printing equipment is a rotary cutting machine (as shown in Figure 20).

The equipment consists of an upper roller and a lower roller. At the same time, it is equipped with high-tech means such as gap adjustment device, stepless speed regulation, electromagnetic counting and photoelectric pneumatic joint control. Die cutting indentation is accurate, safe and efficient. The lower roller is a lower roller and the upper roller is a plate roller. The surface of the plate roller is punched and tapped at a certain distance, mainly to reinforce the installed die-cutting plate. Now the templates are all laminated plates with high temperature and high pressure. Part of the surface of the lower roller is coated with a layer of polyurethane or polychlorinated synthetic material with a thickness of 20-30 mm, and the die cutting thus formed is called soft cutting; Direct contact between steel roller and die-cutting board is called hard cutting. These two die-cutting methods have their own characteristics. Generally speaking, soft cutting is not smooth, especially after long-term use, the surface coating is cut many times and becomes flat, but the tool used has a long life. Some domestic manufacturers reduce the diameter of the lower roller of die-cutting equipment, but the bearing capacity remains unchanged. Then, according to the radius of the original roller, they make aluminum modules that can be installed in half at will and coated with formula grease at high speed. Once the coating surface is uneven in use, it can be changed and adjusted at any time, which is very convenient.

The template used by rotary indentation tangent machine has certain specifications in length and thickness. The length is 800mm, 1200mm,1400mm; ; The thickness is 14mm, 16mm and 18mm respectively. When die-cutting corrugated boards with different structures, it is necessary to choose templates with different thicknesses, which not only ensures the smoothness of the die cutter, but also ensures the original thickness of corrugated boards.

The cutter used in the circular indentation tangent machine is 23.8mm in height and 0.5mm- 1.5mm in thickness. The blades are toothed, linear, single-sided and double-sided. An arc knife with a straight knife at the beginning. For the convenience of use, the back of the arc knife is also provided with a groove with a certain depth. According to the structure of die-cutting corrugated board and the materials used, choose different shapes, thicknesses and blade shapes to ensure the quality of die-cutting.

The pressing line used by the rotary indentation tangent machine is made of high-strength nylon, and the outside is in the shape of ┻. The bottom width of the lower part is 1.5-20 mm, and the widths of the protruding part and the strip surface are 2.5mm, 3.6mm and 4.8mm respectively according to the structure of corrugated board. The height of the protruding part is 5mm and 6mm, and the length is generally 400 mm

The production of die-cutting plate used by rotary cutting machine needs special equipment because of its complex technology and high precision.

Section 4 Common Quality Problems, Causes and Solutions of Corrugated Board

Table 2

Solutions to the causes of quality problems

Poor adhesion 1. The tension of the tissue paper is too high.

2. Face paper and core paper have high water content.

3. The adhesive has small adhesion.

4. Bonding quality

5. Corrugating roller and coating roller are not parallel.

6. Not good

7. The position of the paper guide plate is incorrect or there is dust.

8. The coating roller and the floating roller are not parallel.