Molding process (on)
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Molding of printed matter mainly refers to the special technique of making a printed matter into a desired shape or producing a special effect on its surface by mechanically applying a certain pressure based on the yin and yang mold. According to the mold used in the processing and the final processing effect, it can be divided into two kinds of process technologies: concave and convex embossing and die cutting and indentation.
The concave and convex indentation process uses two corresponding yin and male stencils to emboss a embossed pattern with a three-dimensional effect on the surface of the printed matter by pressure action, and the processing effect is that the surface of the printed matter is deformed.
The die-cutting and indentation process is a process in which a steel plate and a steel wire are arranged into a stencil to roll and shape the printed matter under pressure, and the processing effect is that the surface of the printed matter has both deformation and fracture.
With the development and the continuous improvement of people's cultural living standards, people's packaging requirements for products, in addition to quality, have also increased. Molding processing, with its unique technological advantages, is more and more widely used in the surface processing of various types of printed matter, so as to become a process technology that is indispensable for the finishing of printed materials.
Analysis of a molding process principle
Molded size
Practice has shown that when the thickness of the paper is increased, the shear stress is reduced; conversely, the shear stress is increased. In fact, in the case of a change in the thickness of the paper, the main effect is not the thickness of the paper, but also the ratio of the molded size to the thickness of the paper.
Molded size / molded thickness and shear stress change trend
2. Pressure calculation
In the molding process, due to the different processing objectives and various requirements, the force required for the molding should generally be calculated in advance, so that the machine can be selected and adjusted, and the molding process can be guided.
The mold pressure F1 can be calculated by the following formula: F1=K*α*A
Where: F1 - the force required for molding, the shear stress per unit area in α-molding, the actual area of the A-molded separation surface, calculated from the thickness and circumference of the print, K- considers the actual conditions of the molding process and a series of The coefficient of influence of technical factors.
Production of two-die cutting
The production of die-cutting plates, commonly known as row cutters. The so-called knives refer to the process of splicing steel knives, steel wires and lining materials into stencils according to the specified requirements. In the production of die-cutting indentation, the quality of the row of knives is the key to ensure the quality of the processed products.
Plate making material
※ The bottom plate material. Including wood, PVC and steel
1 Wood version first requires the wood plate to have higher hardness, can withstand pressure, need to be woody wood evenly, cut neatly, tightly and consistently. The loaded knives and wires are tight and uniform. There is no stress in the whole plate, the paper cut out from the die is evenly stressed, no breakage occurs, the wear of the knife is small, the service life of the die-cutting plate can be prolonged, and the wood board has good flexibility, which can alleviate the machete. The wood plate stress caused by the inconsistency is better, and the blade is better and stronger. When the die is cut, it also has a certain cushioning effect, which makes the blade more durable. Suitable for making die-cut plates are birch and eucalyptus. At present, the best quality wood is a Finnish plate with uniform wood, high hardness and good flexibility. The die-cutting die-cutting quality is good. However, it is expensive for imported plates and is only suitable for die-cut versions with high quality requirements. Among the domestic products, the Shanghai board has the best quality, uniform texture, high flexibility and white surface. The northeast board is not uniform enough. It is only suitable for general corrugated boxes, medium-sized boxes, and large curved figures. The quality of the plywood plate is high and the stencil is light in weight. Therefore, the wood floor is usually made of plywood, and the commonly used wood board is 18mm, 15mm birch board. For die-cutting products, 18mm thick wood boards, die-cut corrugated paper or sponge products are used, and 15mm thick wood boards are used. 20mm wood board is used to make die-cut versions of film and self-adhesive products. The commonly used stripping board is 12mm or 8mm wood board.
2 PVC board commonly used thickness of 8mm, 5mm, 3mm, 3mm thick plate to make a composite 18mm knife template, that is, the upper and lower layers are 3mm plastic plates, the middle layer is 12mm wood, and the three pieces are cut and positioned. The rivet is riveted and the knife line is reloaded. Due to the cost of cutting and the difficulty of loading, the cost is higher than that of the wood-cutting plate. In addition, the PVC plastic plate will emit toxic gas during cutting, which is harmful to the metal parts of the equipment and the human body, and is not suitable for promotion.
3 Steel plates with too thick steel plates are not easy to cut, and the cost of the plates is high, so the steel plates are also used to make composite die-cut plates. That is, the upper and lower layers are 3mm thick steel sheets, and the middle is 12mm thick wood boards. Although the cost is returned, the made die-cutting plates are strong and durable, and can be changed many times for the flower plate, because the tool can be changed for a long time. The cost can be reduced, and because the die-cut quality is good, it can be used.
The life of a die-cut version depends primarily on the number of tool changes, and the durability of the different masters is different.
※ Commonly used knives and lines
Steel wire. Steel wire is used as an indentation line in die cutting and indentation processing. There are two kinds of round and fast lines. It is 23mm high and 0.7mm thick.
Steel knife. Steel knives are used as die cut lines in die cuts. Steel knives are divided into single-sided, double-sided and other specifications, generally 23.8mm high and 0.7mm thick. Commonly used knives and wires are made in Sweden, Austria, and Japan. In order to adapt to the processing of various die-cut products, the steel knives are made of hard, medium-hard and soft. Hard steel knives have high hardness and wear resistance, but have small elasticity and small bending flexibility. Therefore, they are suitable for processing products with large processing capacity and thick cardboard and simple shape. Soft steel knives have low hardness but good elasticity and molding. The curvature can be large, so it is suitable for processing small batches, thin paper and complex shapes; medium hardness steel knives are somewhere in between.
The length of the steel knife is less suitable for splicing, and it is generally not suitable for further cutting after forming; the steel blade steel wire after forming should have the cutting edge and the bottom of the knife perpendicular to each other to maintain the steel knife blade edge extension line. Every point on the same plane is in the same plane.
※ Rubber glue plug. It uses the rubber elastic restoring force on both sides of the main steel blade edge of the stencil to push the die-cut cardboard out of the cutting edge. Its original height is 7mm, and the rubber should be 3mm~5mm higher than the edge.
The rubber is generally made of synthetic polymer materials, and the elasticity is divided into three types: hard, soft and neutral. When used, it should be reasonably selected according to the specific conditions.
※ Commonly used processing tools.
Bending machine. Special tools for steel knife and steel wire. It can bend steel knives and steel wires into arcs of any arc and corners of 30 degrees to 90 degrees. In order to expand the scope of use and ease of operation, this type of machine is equipped with a common molding die, a set of commonly used angle bending dies and a set of commonly used circular diameter dies. (about 20 in each group)
Saw machine. The sawing machine is a special tool for sawing wood. Generally, there are many drilling functions. Commonly used saw blades have thicknesses of 0.7 mm and 1.07 mm. The choice depends on the thickness of the die-cutting steel knife, the steel wire and the material being processed.
Twisting machine. It is a special tool for die-cutting indentation. The main function is to cut the steel wire and steel knife into the required size.
With the development of the molding process, a combination machine for die-cutting has appeared. It has a sawing stencil, a cut steel wire, a knife, a corner, and a graphic forming function such as a circle or an ellipse.
※ The bottom mold material.
Its main function is to make the fold line of the pressure-bearing product clear and beautiful, and there is no wrinkle and crack in the fold and the shape is accurate. The bottom mold material is generally adhered to the steel base plate by kraft paper, the kraft paper is soft, and it is easy to manually groove, without pressure resistance, and the indentation is not transparent. At present, a large number of imported bottom mold lines enter the domestic market, such lines are mostly adhesive, the outlet is fast and convenient, the indentation line is full, and the printing durability is high. Different thick paper supply manufacturers have different bottom mold lines, and the basic structure consists of pressure line mold, positioning rubber strip and protective film.
2. Drawing and layout design
※ Drawing
The black and white draft of the molded product is drawn before the molding press, that is, the unfolded view of the individual carton container. Generally, the developed drawing of the molded product is drawn on a plane, the plate making size is marked with a pencil, the finished product size is marked with a color pen, and the broken line of the indented mark is marked with other color pens (to avoid confusion). This figure is the basis for plate making and printing, and is also the basis for press molding. It requires straight lines and precise lines. Draw with a high-precision plotter or plotter.
※ Design of molded version
The structure of the molded version depends on the product structure. The design content of the layout is: the size of the molded layout should match the specifications and working ability of the selected equipment, not only to ensure the processing quality, but also to better play the equipment; to determine the type of molded version; to select the template material and specifications; The position of the grid should be consistent with the printing position; the working part should be located at the central position of the printing plate; the transplantation of lines and figures should ensure the precision required by the product; the layout line should be straight, and the longitudinal die lines should be at right angles to each other and The sides of the stencil are parallel, and the broken and broken lines should be aligned.
In order to make the steel knives and steel wires of the stencil have better die-cutting adaptation, the product design should consider the processability of die-cutting:
1 The hole of the 1 hole should be as full as possible, and the corners of the line should be rounded to prevent the vertical steel splicing.
2 At the joint of the 2 wires, the sharp corner should be prevented from appearing.
3 To avoid the connection of multiple adjacent waste edges, the connecting parts should be enlarged to form a piece to make it waste.
4 Prevent continuous multiple sharp corners, and sharp corners required for reactive performance can be rounded.
5 Prevent the sharp corner from cutting off the middle section of another straight line. This will make the solid knife difficult, the steel knife will be loose, and the die-cutting property should be changed to an arc or increase its encounter angle.
3. Make a template
The layout should be transferred to the plywood before the system. There are two transfer methods, one is manual drawing and the other is photocopying. Hand drawing is more difficult than photography.
※ Production of the bottom plate
Making the master is based on the design of the product or the requirements of the sample. A slit of the inlaid cut line is formed along the curved line on the plywood. The accuracy of the pattern reproduction and the pros and cons of the caulking are the key factors affecting the quality of the molding process.
There are various methods for slotting the bottom plate: lead block discharge die groove; manual wood saw slot; mechanical interface plate cutter groove; laser cutting die groove.
※ Assembly of knives and wires
1 Cutting and forming of steel knives and steel wires. According to the design requirements, the knives and wires used are cut into the largest forming segments and processed into the required geometry.
2 Open the connection point. In the mold making, opening the joint is an indispensable process. The opening connection point is to open a small opening of a certain width in the cutting edge of the die cutting blade. During the die cutting process, the carton and the waste edge of the part are still partially connected after the die cutting, so as to be the next step. And the delivery is smooth. To make the connection point is to use a special equipment knife mouth machine, grinding wheel, open edge connection point, no hammer to open the connection point, causing damage to the knife line and angle, the connection point part of the burr, the die cutter cross bridge Because the position is floating, do not open the connection point at this position.
※ Discharge knives and wires.
The row of knives is based on the product design specifications and styling. After planning the specifications and correcting the printed graphics, the knives can be started. The rowing operation is slightly different depending on the material used for the lining.
When plywood is used as the lining material, the steel knives and steel wires should be embedded in the slats perpendicular to the plane of the bottom plate. The gap is appropriate and should not be deformed or twisted during embedding or processing.
When applying metal empty lead knives, it is necessary to fix the knives directly to the specified position of the embossing plate by using empty lead according to certain process requirements, and complete the arranging operation, which is very similar to the typesetting operation in movable type printing. At this time, the staff is required to be able to Flexible use of all kinds of empty lead, the discharged template can not be loose or twisted during work. Especially when sorting all kinds of geometric figures, it is necessary to ensure the specification of the graphics and to ensure that the tightness is moderate.
When arranging the knives, the interface of the steel knives and steel wires should be placed in the proper position, the interface gap should be appropriate, and the phenomenon that the stencil overlap or the gap is too large can not be caused at the interface due to the pressure. After the arrangement, the longitudinal and transverse lines of the stencil should be at a 90-degree angle with each other, and the edges should be parallel to each other so that the layout will be flat.
※ Bonding die-cut strip
The die-cut strip is mainly used to prevent the die-cutting knife and the indentation line from sticking to the paper during the die-cutting indentation, so that the paper-feeding is smooth, and the elastic die-cut strip is attached to both sides of the cut line. When the die-cut strip is die-cut, it will be compressed and deformed, which will affect the die-cutting effect. If it is too close to the cutting line, the strip will be subjected to lateral stress by the pressure, and it is easy to pull the paper edge during die cutting; if it is too far from the die cutter line, it will not function as it is. Generally, the distance is 1 to 2 mm.
※ Die-cutting template making
Wash the steel plate, then paste a layer of insulating paper on it and then put a layer of carbon paper, then cover a layer of cardboard, and start the indentation. According to the blot, the base paper is cut into strips and adhered to both sides of the indentation to form an indentation groove. Generally, the thickness of the bottom mold is less than or equal to the thickness of the die-cut substrate, and the indentation effect is different depending on the direction of the line of the indentation line and the direction of the fiber, and the line of the indentation perpendicular to the direction of the fiber is folded and full, so When the line is used, the indentation line in the direction of the straight line is preferably narrow by 0.1 mm.
※ Pad version
After the stencil is completed, the stencil should be mounted on a die-cutting machine for trial cutting. During this process, the test specimen is partially normal, and some of the specimens are not cut through.
A 0.05 mm thick stencil sheet was adhered to the bottom of the stencil to height compensate the die cut.