Sheet-fed offset printing machine connection device characteristics

In order to cope with the continuous shortening of the printing cycle, the continuous improvement of quality, the increase in demand for short-lived games, the intensified competition, and the ever-smaller profit space, the addition of wiring devices to sheetfed offset presses can not only improve efficiency, but also differentiate development. Printing, improve competitiveness. However, the configuration of the connection device must be selected realistically according to its own needs, and it is appropriate to meet the needs. Otherwise, it will not only increase the investment in the purchase of equipment, but also make the device structure complicated, inconvenient to use, and superfluous.

First, web - single sheet feeder

Roll paper - The single-sheet feed machine cuts the web into individual sheets and feeds them directly to the paper feeder of a sheet-fed offset press. As web-single-sheet feeders can reduce costs and improve efficiency, they have become more and more important after 2005.

Web--Single-sheet feeder continuously cuts online web into single sheets. The cut sheet is fed directly to the front sheet of the original single-sheet paper feeder according to a certain step and position. So that the paper feeding mechanism can feed the paper into the impression cylinder, which can replace the original single-sheet paper feeder. The cutting length of the web can be adjusted steplessly according to the needs of the printing paper. The characteristics of the main wiring device and the selection cutting accuracy can generally reach ± ​​(0.2-0.5) mm, and the width is the width of the web.

There are some differences in the structure of different web-sheet feeders, but the basic principle is the same. They are generally composed of a paper roll holder, a floating roller unit, a feed roller, a cutting unit, an intruder unit, a nested printing logistics and Paper roller and other components. The function of the floating roller unit is to reduce or eliminate the change in the tension when the web is unfolded, so that the paper strip enters the feed roller more smoothly and is ready to be cut. The performance of the roller unit determines the precision of cutting the paper. Integral units and nested printing logistics, the cut sheet paper according to a single sheet offset press on the paper step requirements, the cut paper stack.

With the web-single-sheet feeder, you can cancel the original single-sheet feeder and directly connect the web-sheet feeder to the printing unit. The original sheet-fed paper-feeding machine can also be fixed, and the web-single-fed paper-feeding machine is installed behind the original single-sheet paper-fed paper-feeding machine, and the web-single-fed paper-feeding machine is transported. The table is lengthened and directly connected to the original sheet feeder paper feeder paper table. The former covers a small area and is cheap, but its flexibility is poor. The latter covers a large area and is expensive. Sheets and webs can be used. It is very flexible.

Advantage

First, large amounts of paper can be stored to reduce paper change and downtime and increase machine availability. Second, webs are cheaper than single sheets and can reduce paper costs by 5% to 25% if coated paperboard or film is used. , With coils can also obtain higher economic benefits; Third, the cutting length of paper can be adjusted steplessly, easy to use, will not produce a sheet of paper before the print head, ground feet and cause paper waste; Fourth, Can make it waste the thin paper and thin plastic that can not be used by the sheet-fed offset press to print; Fifth, completely solve the double-sheet or multi-sheet feed failure; Sixth, the operator does not need to pile paper, reducing the labor intensity.

Disadvantage

First, webs cannot be selected beforehand. Therefore, the requirements for the quality of webs are relatively high. It is required that the webs have no or few joints, the standard of the paper roll (without ellipticity, taper, etc.), and the paper roll cannot have wrinkles. Paper itself cannot have quality defects (such as holes, tears, tears, etc.). Second, web humidity is not as dry as a sheet of paper. It should have certain requirements for the dryness of directly used webs, and should pay attention to the dry humidity and the quality of the paper during the roll storage process. influences. Third, the flatness of the paper is best when it is large. The worse the core is, the thicker the paper becomes. Thicker paper, paper near the paper core may affect use, and it may be necessary to add a flat paper device. Therefore, too thick paper or cardboard, corrugated board should not be used.

Second, film, plastic sheet printing and corona treatment

Sheet-fed offset presses can also be coated on-line, such as the Roland 700, which can coat the printed material before color printing begins.

The first unit of the printing press prints viscose on the substrate and the second cylinder has a film wrapped around the blanket. After the printing material has passed, the corresponding part is covered with a film. This process is done at normal temperatures, completely avoiding the effects of temperature on the film and printed material.

Sheet-fed offset presses can now also be printed on plastic sheets, but the adhesion of the ink on the surface of the plastic sheet is poor. For this reason, online corona treatment can be provided. Such as KBA Rapida74, Rapida105 and other models can be installed in front of the first printing unit corona unit, the special material (such as plastic sheet) surface high-pressure discharge treatment, improve the adhesion of ink on the surface of the material, thereby improving the printing Quality and speed. In order to solve the problem of overprinting and other issues caused by temperature changes in the plastic printing process, KBA can also provide dedicated scratch-resistant paper guides, plastic sheeting static removal devices, and impression cylinder cooling devices.

Third, online cold stamping

Now many sheetfed offset presses can provide on-line cold-stamping devices. The first unit before foiling presses the special adhesive on the paper according to the pattern needed for the cold-foiled aluminum foil. The second unit equipped with the foil-discharging mechanism will use aluminum foil. Bonding (hot stamping) At the place where the adhesive is printed, the remaining aluminum foil is taken away by the winding mechanism above the third unit. When cold stamping is not required, the first and second units can be printed as normal as other units.

Advantage

(1) Printing and hot stamping are completed at one time, and precise overprinting can be achieved. Because the special adhesive can be used like ink, very fine pattern and text stamping can be achieved.

(2) Cold stamping without heating, will not cause paper deformation, will not affect the printing on and after the aluminum foil.

(3) can be printed on the aluminum foil, so that the aluminum foil to form any graphics and special color effects, such as printing silver and magenta on the silver foil to get gold.

(4) Since the aluminum foil can be given different colors by reprinting, the printer does not need to purchase aluminum foils of various colors, and only silver foil is required, which can reduce inventory and warehouses.

(5) The operator does not need to master the hot stamping technology, as long as the offset printing technology can be applied.

(6) When the hot stamping is not performed, the original unit can perform normal printing.

(7) Cold stamping system can be installed on old machines.

(8) Packaging printing often requires an online cold stamping device that can be installed anywhere on the machine as needed.

Disadvantage

(1) When printing on aluminum foil, the drying time of the ink is affected. If necessary, a drying device or a coating and drying device should be added.

(2) In the current hot stamping structure, the utilization rate of aluminum foil is low, especially single-scroll type. The use of multi-scroll type can improve the utilization of aluminum foil and reduce the cost of use.

Fourth, connect the light and dry

Now packaging can not only protect the goods, but more importantly, it can stimulate people's desire to purchase, and even become one of the criteria for deciding to purchase. Therefore, about 80% of folding cartons, 70% of labels, and many books and magazines use glazing technology to attract people's attention.

Standard offset printing units can also be glazing or printing metallic inks, such as coated offset printing inks. However, due to the thin ink layer and the use of wetting liquids and additives, the glazing effect is not good. Therefore, at present, the coating device mainly adopts flexographic printing, and generally there is one or two separate coating units. When the coating requirement is very high, two coating units are required. The first coating unit is generally water-based varnishes to act as a seal for the ink and the surface of the paper to reduce the penetration of bleed inks due to the first coating. Loss of light caused by paper. After drying, the second coating can make the distribution of the varnish even more uniform, forming a high-gloss glazing layer. The second glazing unit can use UV varnish, its effect is better than pure UV, it can also use water-based varnish to further improve the glazing effect, or use a special effect pigments to show special effects.

Double glazing units are generally located at the rear of the printing unit, and drying units are provided behind each glazing unit. If it is necessary to apply opaque white or a special effect primer to the surface of the substrate prior to printing, a flexographic coating unit and drying device should be installed before the first printing unit. The selection of coating units should be based on the requirements of the printed matter.

(1) Selection of oil supply mode: The coating machine is mainly provided with different types of light oil. The amount of varnish can be adjusted according to the need. Generally, the gap or pressure of the two rollers is adjusted, and the rotation speed of the roller is changed. This kind of mechanism is currently widely used, but adjustments are troublesome.

The newly developed closed type varnish supply device consists of an anilox roller and a chamber scraper. The cavity box is equipped with two scrapers, one of which is applied with a lacquer evenly along the direction of rotation of the anilox roller, and the other is rotated against the direction of the anilox roller to scrape off the excess coating on the anilox roller. The size of the anilox roller access hole determines the amount of varnish used, and the amount of varnish is easy to control. If you need to change the amount of polishing oil, you need to change the anilox roller, therefore, the coating device is often equipped with 2 to 3 different network size anilox roller. The standard holding oil amount of the general anilox roller is 20 cm3/m2, and the thickness of the varnish layer printed on the substrate is about 8 μm, and the basis weight is 8 g/m2. This chamber type coating oil supply device can prevent dust, flying ink and varnish from drying up the skin. The installation position of the cavity squeegee must be correct, otherwise it will not work properly. The general cavity type coating oil supply device needs to be equipped with an automatic polishing oil pump for automatic coating of oil.

(2) Selection of glazing roller: When coating all, the coating plate is generally a blanket. In the case of partial coating, the coating plate is generally a flexographic plate, which is mainly composed of a rubber plate and a polyester plate.

Whether the glazing roller needs to be adjusted depends on the coating requirements. Only the entire coating, roller generally do not have to adjust. In order to accurately overprint the part when the light is applied, it is required that the glazing roller can be adjusted axially and circumferentially, and when the requirement is high, the diagonal adjustment of the roller is also required. Medium-to-high-end machines generally control the adjustment of the glazing roller on the center console.

After drying, it must be dried immediately. Sheet-fed offset presses are often based on the needs of the print, water-based coating, UV coating, and the requirements of the print and change at any time. There are roughly two ways to dry it. That is, the use of oily ink + water-based varnish, IR (far-infrared) and/or hot air drying; UV ink + UV varnish, using UV dry curing. Of course, it can also be an IR/UV combination. The specific choice should be based on the varnish and product use. There are three types of UV curing devices, namely, the inner baking plate method, the drying unit pattern, and the long line conveying method. The inner baking method does not require a special unit and is generally installed between the units. It is convenient to change the installation position, but the drying capacity is the lowest among the three methods. The drying unit method requires special units but the highest drying capacity.

The long-distance transmission method is to increase the paper-feeding distance. After the last coating machine, IR, UV and hot air drying equipments are installed, taking into account IR/UV drying methods (varying drying methods or drying lamps for varnishes). The plate method and the drying unit method are difficult to use both IR/UV drying methods, and in order to reduce the thermal deformation of the paper, a low-heat type UV device or an additional cooling device (usually behind an extended UV lamp) can be used.

In order to adapt to the variability of the surface of a sheet-fed offset printing machine, generally in the rear of the last printing unit or coating unit of a sheet-fed offset printing machine, infrared, UV, hot air drying devices are also provided to form an elongated delivery device. Prints need to open different drying devices. Such as water-based glazing, infrared and hot air drying devices, both with a very good drying effect. UV glazing starts the UV drying device.

In general, the extended delivery device is also equipped with a cooling device (recycled cold air), which cools the printed paper on the one hand and helps the ink dry on the other.

In order to ensure proper ink drying between the various colors of the printing unit, it is necessary to install a UV or infrared drying device between the printing units and both can be replaced.

V. UV offset printing

UV printing was first applied on screen printing and then applied on flexo printing. UV offset printing has developed greatly in the past 10 years. UV offset printing can be roughly divided into color printing and surface finishing. Color printing and conventional printing are basically the same. Surface finishing such as UV glazing can be used instead of lamination, either fully or partially. Using UV ice or UV matte ink printing, you can form a "three-dimensional" image and colorful texture effects on the surface of the substrate. In recent years, UV offset printing and composite ink printing have emerged with many advantages. Of course, there are also respective problems.

Disadvantage

(1) Special supporting device: printing equipment

UV offset printing must be equipped with special rubber rollers, printing plates and blankets, and special cleaning agents are needed for cleaning; ink rollers need to increase the water cooling system; due to poor UV ink overprinting, it is generally necessary to add special UV inks between the units. Curing drying device.

(2) High printing cost: First, the price of UV equipment is high, and the depreciation cost is high; Second, UV ink is expensive, generally 4 to 5 times that of common ink; Third, the management and operation cost is high, and the content of UV offset printing technology is higher. High, must have a sound process plan and strict management, increase management costs. Due to the lack of workers skilled in UV printing technology, UV printing operators have high wages.

(3) The process is more complex and difficult: First, the point of UV ink ink balance tolerance is relatively narrow, easy to cause more serious ink emulsification, dirty version, increased the difficulty of operation; Second, UV ink curing degree is not easy to grasp, dry is not complete , Dirty printed materials, high curing temperature, which may cause paper deformation affect overprinting; Third, UV inks require high color sequence, improper arrangement of color saturation will be affected; Fourth, UV ink drying fast, stop printing Long time or machine speed is too slow, the ink may crust or even dry, affecting the printing quality.

Six, double-sided sheet-fed offset printing machine

With the development of double-sided offset printing presses, double-sided coating was mentioned on the agenda. The difficulty with double-sided coating is that the first side must be fully dried after the coating is finished. In addition to UV printing and drying can be carried out immediately (the cost of UV printing is high, some prints can not be UV printing) water-based coating is mainly dry time is not enough. Komori recently introduced two processing units behind the first group of coating units. The processing unit has no plate and blanket cylinders, only the impression and transfer cylinders, so that the paper has sufficient drying time before it is turned. .

Advantage

First, there is sufficient drying time to ensure that the coating is dry after drying; secondly, it facilitates the discharge of heat that results from drying; and thirdly, it improves the drying ability. In order to adapt to changes in water and UV coating, IR and UV drying are added at the same time. The device is adapted to the requirements of different printing and glazing for drying, and the scope of use of the machine is increased. Fourthly, the printing quality and production efficiency are improved, and the rejection rate is very low.

Disadvantage

Due to the addition of two processing units, the product price is higher and the area is increased.

Seventh, connection number, embossing, punching

After the printing unit, it can be completed by a single marking and embossing unit, or a simple marking and embossing device can be installed on the printing unit. It consists of an ink supply unit and a code box axis. The direction of the number on the number box axis is different, and vertical or horizontal numbers can be printed on the print sheet. Remove the number box and press the convex block in place to emboss the print. FIG. 5 is a perforation device configured on a sheet-fed offset printing press. In the longitudinal direction (printing direction), punching, cutting, creasing and embossing are performed by mounting a corresponding tool (such as a perforating knife) on a bracket that is mounted at a position to be machined (horizontally adjustable.). Holes, cuts, indentations, and embossing are made in the transverse direction (perpendicular to the direction of the paper), and the relevant processing tools are mounted on the supporting shaft. Whether longitudinal or transverse drilling, cutting, indentation, and embossing are all The associated tools and the impression cylinder are squeezed. Therefore, there should be protective measures on the surface of the impression cylinder.

Eight, line cutting, indentation

In recent years, die cutting and creasing devices have also been installed on sheetfed offset presses. The initial die-cutting and indentation is performed on the coating machine, ie, the die-cut version is mounted on a glazing roller. The position of the glazing roller on the die-cutting position is adjusted to die-cut or indent the die. Some also put the die-cut version on the blanket cylinder and squeeze it with the impression cylinder. It is now possible to have a separate die-cutting unit.

Individual die-cutting and indentation units can be equipped with stripping devices. A suction and blowing system is equipped on the die-cutting drum. The die-cut waste is firmly sucked on the die-cutting drum. When the die-cutting drum is turned to the exhausted air-drawing position, the suction of the die-cutting drum is immediately replaced by blowing, and the die-cut scrap is blown away. Was exhausted exhaust system sucked away.

Whether it is die-cutting, indentation, embossing or punching, the surface of the impression cylinder needs to be protected. Generally, a lining or a sheath is used.

Six, double-sided sheet-fed offset printing machine

With the development of double-sided offset printing presses, double-sided coating was mentioned on the agenda. The difficulty with double-sided coating is that the first side must be fully dried after the coating is finished. In addition to UV printing and drying can be carried out immediately (the cost of UV printing is high, some prints can not be UV printing) water-based coating is mainly dry time is not enough. Komori recently introduced two processing units behind the first group of coating units. The processing unit has no plate and blanket cylinders, only the impression and transfer cylinders, so that the paper has sufficient drying time before it is turned. .

Advantage

First, there is sufficient drying time to ensure that the coating is dry after drying; secondly, it facilitates the discharge of heat that results from drying; and thirdly, it improves the drying ability. In order to adapt to changes in water and UV coating, IR and UV drying are added at the same time. The device is adapted to the requirements of different printing and glazing for drying, and the scope of use of the machine is increased. Fourthly, the printing quality and production efficiency are improved, and the rejection rate is very low.

Disadvantage

Due to the addition of two processing units, the product price is higher and the area is increased.

Seventh, connection number, embossing, punching

After the printing unit, it can be completed by a single marking and embossing unit, or a simple marking and embossing device can be installed on the printing unit. It consists of an ink supply unit and a code box axis. The direction of the number on the number box axis is different, and vertical or horizontal numbers can be printed on the print sheet. Remove the number box and press the convex block in place to emboss the print. FIG. 5 is a perforation device configured on a sheet-fed offset printing press. In the longitudinal direction (printing direction), punching, cutting, creasing and embossing are performed by mounting a corresponding tool (such as a perforating knife) on a bracket that is mounted at a position to be machined (horizontally adjustable.). Holes, cuts, indentations, and embossing are made in the transverse direction (perpendicular to the direction of the paper), and the relevant processing tools are mounted on the supporting shaft. Whether longitudinal or transverse drilling, cutting, indentation, and embossing are all The associated tools and the impression cylinder are squeezed. Therefore, there should be protective measures on the surface of the impression cylinder.

Eight, line cutting, indentation

In recent years, die cutting and creasing devices have also been installed on sheetfed offset presses. The initial die-cutting and indentation is performed on the coating machine, ie, the die-cut version is mounted on a glazing roller. The position of the glazing roller on the die-cutting position is adjusted to die-cut or indent the die. Some also put the die-cut version on the blanket cylinder and squeeze it with the impression cylinder. It is now possible to have a separate die-cutting unit.

Individual die-cutting and indentation units can be equipped with stripping devices. A suction and blowing system is equipped on the die-cutting drum. The die-cut waste is firmly sucked on the die-cutting drum. When the die-cutting drum is turned to the exhausted air-drawing position, the suction of the die-cutting drum is immediately replaced by blowing, and the die-cut scrap is blown away. Was exhausted exhaust system sucked away.

Whether it is die-cutting, indentation, embossing or punching, the surface of the impression cylinder needs to be protected. Generally, a lining or a sheath is used.

Twist Packing Machine

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