Analysis of Processing Technology and Problems of Carton Back Road

At present, people have higher and higher requirements for packaging cartons. The outer packaging must not only print the images and color patterns of the items to be packaged; some even require that notched corners be used, and die-cutting is required to cut corners. The edges are not smooth,. In view of this situation, how the carton industry should carry out the post process processing of the carton is particularly important.

Process browsing

Corrugated box molding process can be divided into:

Feeding - printing - slotting, crimping - die cutting - folding, sizing - nail box combination - stacking - packaging and other processes. In short, it can also be said that printing, molding and joining are three big steps.

Feeding

Feeding is also the paper feeding process. It is mainly the smooth and accurate feeding of corrugated board to the printing system. Because corrugated paper has sufficient stiffness, sheet-fed input is usually used. After printing the stencils, they are neatly placed in a fixed position on the stacking table for manual feeding or manual feeding. The automatic paper feeder adopts an automatic lifting table, which can automatically adjust the height of the paper stack. The input uses the suction method to overcome the phenomenon of cardboard jamming due to the unevenness of the paperboard. A diagram of the automatic suction feed section can be seen in FIG.

Pressure line, slotting, cutting angle, slitting

In the printing slotting unit, this part is mainly composed of upper and lower roller wheels, upper and lower slotted knives, upper and lower corner cutting knives and slitting knives. When the cardboard passes, the upper and lower roller wheels mainly complete the vertical pressure lines of the corrugated cardboard; the upper and lower slitting blades cut the lower concave knife to complete the opening of the corrugated cardboard; the upper and lower corner cutting blades pass through the upper corner The blade and the lower knife pad complete the forming of the joint of the corrugated box, and the slit is trimmed to the specified size.

The main function of the pressure line is to accurately bend the corrugated board at the predetermined position so as to achieve an accurate internal size of the carton. It can be divided into vertical pressure lines (indentation lines parallel to corrugations) and horizontal pressure lines (indentation lines perpendicular to corrugations). A circular indentation process is used on the printing slot machine, and the paired press molds are rotated in a disc shape, and the cardboard passes between pairs of press molds to leave indentations. Adjust the gap between the die and punch to change the depth of the indentation. The indentation should be clear and unbreakable with the indentation inside the paper.

Slots are cut into corrugated cardboard to facilitate folding. The width of the board is usually 1mm thick (sometimes twice the board thickness). There is a close relationship between the slotting and the indentation of the carton, which has a direct impact on the carton dimensional accuracy and appearance.

Die cutting

After the forming of the corrugated carton, the plane unfolding structure consists of the contour cutting line and the indentation line. Molding is the main process feature. Especially for some non-linear contoured structures and functional structures, such as unequal heights of the inside and outside rocking covers, and handle holes, ventilation holes, etc., only the molding method is used to facilitate molding. Therefore, die-cut indentation is one of the key processes in the carton (box) manufacturing process. Die cutting can be made online or it can be done separately.

FIG. 1 is an example of a molding press. The die-cut part can be a flat press die press or a round press die press, and both are equipped with a stripping device that can automatically eliminate corner scraps generated after die cutting.

Figure 1. Schematic diagram of two-color printing die-cutting and automatic skinning device

1-Cardboard 2-Printing3-Die Cutting4-Suction Automatic Exhaust 5-Fan 6-Hair Blow 7-Transport Unit

8- Product Delivery 9- Bed 10 - Suction Conveyor 11 - Suction Conveyor 12 - Vacuum Feed

Waste and accumulation

The main purpose of this process is to draw out the swarf that is cut, cut, and cut off by the suction of the air pump. This can maintain a good working environment for the venue. In the figure, the automatic suction waste removal device can be seen. The stacking part is connected to the printed cardboard through a conveyor belt, and then the corrugated cardboard, which can be printed and grooved, is stacked on the rack by a conveyor table that can be adjusted up and down to enter the next process.

Folding section

The folding section is a main process of the rear carton processing of the entire carton. With the help of the escort bar, the folding process is completed by the inverted belt. The escort rod is positioned on the diagonal roller wheel near the top and the belt is flipped over here so that bouncing and chattering can be avoided so as not to damage the cardboard. The cardboard is carried by the chain system through the folded gluing section and glued by the rubber wheel. The sprocket is mounted on the inner side of the folding arm and the top block is mounted on the chain. They can precisely control the parallelism and verticality of the cardboard. The conveyor guide on the folding rails transports the cardboard to the folding arm for folding.

Nail box bonding

Carton joints mainly use three methods: nailing, bonding and gluing. The former two are used more often. Another new type of HL staple-free carton on the market is the adhesive bonding of carton joints after special processing.

The adhesive nail box is used to manually or automatically feed the slotted lined carton board into the glue application mechanism, and the glue wheel is used to glue the tongue and use the function of a folding bar or a guide wheel to bend the paper board. Closed and overlapped, the pressure roller at the lap joint presses the glued tongue to enhance the bond strength. Glue is connected by adhesive tape. The process is to attach a tape feeding, cutting and pasting device on the gluing machine so that the interface of the cardboard after the grooving pressure line is aligned and aligned according to the form of butt joint, and then the adhesive tape is applied. , making it a cartons finished product. HL nail-free carton joints are processed by planing process, making the tongue-in-a-step, “T” structure, and glued into a box after being glued on the rubber wheel. After the box, the carton face paper is overlapped with the face paper, and the corrugated board is overlapped with the corrugated board. The overlap thickness and the corrugated board thickness are uniform, and almost no overlap is found. In addition, HL carton board processing does not need to slot, cut corners, carton box seamless whole body, with a closed shell, no strength weaknesses and other advantages.

Stacking and launching

The accumulation part consists of counting, stacking, and pushing. After the cartons are folded and nailed, the cartons are fed into the hopper by the bottom stack feeder, and then the number of cartons per bundle is selected, and the cartons are sent out by the bundle ejector to complete the processing of the entire subsequent process.

Problem analysis

Paper feeding section

Problem: The front, back, left, and right sides of the paper feed section are improperly adjusted, or the warpage of the paper board is serious. As a result, the paper board cannot smoothly enter the next process, which makes paper feeding difficult and clogged, resulting in inaccurate or damaged paper board feeding.

Solution: Adjust the distance and clearance of each baffle in the paper feeding section, especially the front and rear baffles. The front baffle should adjust the gap according to the thickness of the board to ensure that only one board can be passed at a time. The gap between the upper and lower ends of the paper feed roller must be kept parallel to prevent paper feed skew; the gap should be slightly smaller than the thickness of 1 paper board, but not too low. In order to overcome the paper feeding difficulties caused by the warp of the board, the tailstock is raised and a small portion of the paperboard stays on the paper feed table. If scrapers are used, it should be noted that the stacking height of the cardboard on the feeding device is generally about 450 mm. The cardboard size is too high or too low, and the depth of the notch will be affected after feeding.

Slotting and crimping

Problem: The slot size is inaccurate, the depth is inconsistent, the knife edge is not clean, and the base blade guide plate wears and removes the chipping difficulty. Improper adjustment of the cam concave cam clearance, up and down is not centered, the depth is not enough, there is a problem of inconsistent creases, fractures at the indentation, and cracks in the pressure lines.

Solution: Slotting and crimping dimensions are to be determined according to the manufacturing dimensions of the process drawing design. The slotted knife and holder must be tightened. When the paperboard is too narrow, each part of the transfer roller (also known as the pull roller) should be adjusted to the position of the pressure line, the gap should be slightly less than the thickness of a paperboard, and the transfer roller should be used as a transfer function. Frequently inspect and replace wear tools in a timely manner to ensure that the upper and lower blades are installed in pairs. Adjust the depth of the knife according to different types to ensure correct indentation specifications. Check for loose guide plates and replace if worn. The position of the pressure line must be in the middle of the slotting knife. If there is a cardboard breakage, the quality of the raw material must be considered. Due to the cracking of the pressure lines caused by the drying of the paperboard, the water content of the paperboard can be increased by spraying water. According to the paper, cardboard dry humidity to adjust the pressure line depth.

Die-cutting section

Problem: The position of the stencil is not consistent with that of the cardboard; the position of the die-cutting and printing is not aligned; the rules of the paperboard garnishes are not the same; the deformation of the paperboard makes the position of die-cutting indentation inaccurate. Die cutting edge not only, die-cutting board glued knife version.

Solution: According to product requirements, re-calibrate the template, printing and die-cutting parts; adjust die-cutting paper-feeding positioning rules so that the paper-feeding position is consistent; and reduce the impact of the paperboard itself on die-cutting quality. Use a steel knife with good die cutting adaptability, and always check and replace the worn steel knife. Reasonably choose different hardness of the rubber, pay attention to sticking when the density should be appropriate distribution; proper adjustment of die-cutting pressure. The tightness of the row cutter knife should be appropriate, pay attention to adjust the height of the copper wire, and re-adjust the pressure of the steel knife to replace the pad paper in time.

Folding section

Problem: The paper feed is skewed, folded incorrectly, and jammed. The gluing is completed in this process, mainly due to uneven sizing and poor adhesion.

Solution: Adjust the tightness of the conveyor belt and the chain and the parallelism of the eject module, and move the folding arm to a predetermined position. According to the thickness of the paperboard, the pressure of the driving roller should be adjusted to ensure the normal operation of the paperboard. To check if there is enough glue in the tank that supports the tire, check the return pump for damage or clogging. The pressure of the rubber wheel should be appropriate and the adhesive should be evenly coated on the connecting edge.

Combined section

Problems: poor adhesion, adhesive spillage, carton adhesion, inconsistent width of joints, upper and lower mouths are scissors. In the nail box engagement, the position of the nails in the nail box and the nail pitch are inaccurate, the nail saw is damaged, rusted, the nails are not firm, the mouth is not uniform, the width is not uniform, and the nail is broken.

Solution: Consider the viscosity of the adhesive and the uniformity of the coating. If the adhesive overflows and the carton sticks, the longitudinal movement of the glue part and the tire rubber is adjusted to the predetermined position. Adhesives should not be too thin. The pressure of the rubber wheel should be appropriate and the adhesive should be evenly coated on the connecting edge. (mainly adjusted in the folded part)

When nailing boxes, check the hardness, thickness, bending, and whether there are rust, cracks, etc. Head and tail screws must be within 20 mm from the bottom line of the indentation as required by the standard and the saw should be stapled along the center of the lap tongue. The pitch is not uniform and the speed of the feed belt must be adjusted. Check whether the silk channel is unblocked, whether the single, double prongs and square knives are sharp, and whether the tack nipples are centered to ensure that the lower tack nozzles are compatible with the thickness of the processing carton.

Stacking section

Problems: Inaccurate counts, clogging, difficulties in launching, etc.

Solution: To solve the problem of inaccurate quantity, we must first check whether the timing of the counter and the ejector is accurate, and whether the carton is slipping, skewed or out of sync during folding. The adjustment of the bottom stacker feeder should be based on the principle of ensuring good feeding, so that the inclination is as small as possible. The number of cartons in the hopper and the number of cartons per bundle must be adjusted appropriately. To align the cardboard, the distance between the front pallet and the pusher should be a few millimeters smaller than the slot height. In order to ensure that the carton is in the correct position in the hopper to ensure proper discharge, the pressure at the stapling and bonding points of the carton must be adjusted. Depending on the size and form of the carton, it is determined that it is pressurized at one or two locations. It is necessary to make the pressure supply and ejector timings as fast as possible. If the cartons are pushed too fast and each bundle of output is skewed, check if the feed path is obstructed and if the rollers are stuck.

In short, a good printing product is not the result of a single production process. From the beginning of product design to the end of production, every link must be closely coordinated, otherwise it will affect the quality of the product. There are many problems in the downstream processing. Enterprises should analyze the problems and take measures according to the actual production equipment. strict requirements