The Structure, Characteristics And Common Defects Of Roller Printing Machine

Roller

printing

The printing process of copper roller with concave pattern is called roller printing, also known as copper roller printing.

The carved cylinder is called the flower pot for short.

When printing, first make the surface of the flower tube with color paste, then use the sharp and smooth scraper to scrape the surface color of the non carved part of the flower tube, and leave the color paste in the concave pattern.

When the flower tube is stamped on the fabric, the color paste is pferred to the fabric and printed with patterns.

Each flower pot is printed with one color paste. If there are more than one flower pot on the printing equipment, the color pattern can be printed continuously.

Roller printing has the advantages of clear flower pattern, full color, and high productivity, but it has some limitations in production because of its high tension, difficult operation, high labor intensity and limited printing number.

The biggest difference between the rotary screen and the rotary screen is that the roller printing is the floating pulp, and the circular net is the upper floating pulp.

That is to say, the larger the cylinder pressure is, the lighter the color is, and the color will deepen after the compression of the cylinder.

This is the focus of the next process.

The first color of roller printing will be very shallow after printing several sets of coloured rolls. Only the last color will be the same as the small sample.

That is to say, if printing four sets of colors, the depth of the color will be shallower from four to one compared with the small sample, so the next process should be deepened according to experience.

This won't happen in a circular net.

Of course, the first line of color is the clearest.

The above mentioned mainly refers to reactive printing, and it is quite different for paint to be simple.

Main structure of 1.1 roller printing machine

(1) cylinder: copper zinc alloy as raw material, according to flower pattern corrosion etching into a certain concentration of shade, to accommodate color.

(2) scraper: white steel, blue steel, stainless steel three kinds, white steel is hard (suitable for fine, moire and other flower type), blue steel is soft (suitable for large area), stainless steel chemical corrosion resistance.

We often use blue steel.

The scraper is mounted on the top of the flower barrel in the running direction of the flower barrel, and its function is to scrape the size of the non flower part on the flower barrel.

The quality of the mill is directly affected by the quality of the mill and the angle of its installation (19-35 degrees of intersection with the flower tube).

Therefore, those who can control roller machines are highly experienced people.

(3) small knife: scrape off the floral and other impurities and surface residual pulp on the surface of the flower barrel, so as to prevent color pmission.

It is placed behind the flower tube in the direction of the flower barrel, and the requirement for sharpening it is lower.

(4) for the flower gear: the roller printing machine is equipped with the internal and external gears and pmission gears at the other end of the shaft, that is, the advance lag of the flower tube is adjusted by the rotating gear, so as to achieve the purpose of flower.

Later, electric power was used to reduce labor intensity.

1.2 arrangement of flowers:

In principle, it is from shallow to deep, from small to large, but the arrangement of flower arrangement must take into account the actual production factors, and consider many aspects, such as flower structure, color brightness, fabric thickness and so on.

Generally look at the theme of the sample to show, highlight the key points, take into account the overall effect, combined with the actual level of production capacity, generally fine patterns in front of the large area in the back; bright colors in front, behind the dark; similar colors, flowers closely related to the row.

But for example, there are dark green leaves in a green leaf. In the arrangement, it is suggested that the dark leaves should be arranged first and the light colored leaves should be arranged to achieve clear outline.

1.3 common defects:

(1) knife bar: form one or more color lines on the fabric surface.

The main reason is that the scraper has a small gap (the knife has been worn for a long time, the surface of the cylinder is rough, etc.) or there are impurities (such as undissolved substances in the color paste, etc.).

(2) drag: a small part of the non flower part with the same color or different colors is drawn under the flower pattern.

The reason may be that 1. scrapers are installed too high, and the 2. color paste is too thick to cause the fabric to be absorbed instantaneously, and then the flower tube is brought into the pattern and the 3 tube arrangement is unreasonable.

Generally, it can be solved by adjusting the cutter angle, the thickness of the paste and the knife.

(3) jumping knife: pverse striations left on the fabric as the blade flickers and the slurry on the cylinder is not scratched.

The main reason may be that the scraper is installed too low, causing the blade to flicker or the weight of the hammer is insufficient. Of course, the improper installation of the tube and the tightness of the gear can also cause a jump knife.

(4) open field (bottom): the pattern of the printed fabric is exposed.

Causes: fabric low efficiency, too thick slurry, speed too fast, pressure is not enough, shade is too shallow.

If the shaft is bent, it will cause color difference between left and right, or even open field.

(5) splashing slurry: splashing some spots from the edge of the knife to the fabric.

If the scraper is installed too low, the speed is too fast, the slurry is too thin, and the flower tube is cross stripe, it is easy to produce such defects. If the adjustment is still unable to solve, a piece of cloth can be covered above the flower pot to cover up the defects.

In addition, if there are sand holes on the flower drum, the color points will be regular and different from the splash.

In fact, defects produced in production are far more than that. This requires operators and craftsmen to think more quickly, analyze and solve problems quickly, so as to ensure quality.

1.4 engraving

The printing speed of roller printing machine can reach 120 m / min, usually 70~100 M / min.

Commonly used roller printing machines can only print one side.

If two mainframes are connected in series and equipped with two sets of flower shaped symmetrical patterns, they can print double sided printed fabrics with positive and negative sides.

The vertical cylinder printing machine's flower tube is arranged longitudinally, and each cylinder has a small bearing roller.

The flower barrel is made of iron hollow roller copper or cast by copper. The circumference is generally 400~500 millimeters. The length depends on the working range of the printing machine.

The pattern is composed of dots or lines.

The carving of the flower barrel is the process of making concave patterns on the surface of the copper roller.

There are five ways of carving patterns.

(1) hand carving: using simple tools such as graver, chisel, nail and so on to make patterns on copper roller.

This method is only used for carving flowers and carving special fine patterns.

(2) steel core engraving: using a hardened steel male die to roll into a concave pattern on the surface of the copper roller, it is an earlier mechanical engraving method, suitable for carving fine patterns, geometric patterns and straight patterns.

(3) reduced carving: used in 1850s, it can engrave all kinds of patterns.

First, the pattern is magnified 2~5 times on the zinc plate, and the pattern groove is formed on the zinc plate by etching or manual processing.

Then the pattern on the zinc plate is restored to the original size by reducing the engraving machine. The diamond roller is applied to the copper roller with uniform wax coated on the surface, exposing the flower shaped copper surface, and then the etching is etched into concave patterns in the etching tank by chemical or electrolytic method.

This method can make the marks on the flower barrel smooth and accurate, and more needles can be installed on the reduction machine, and the same pattern is carved on the same cylinder simultaneously.

(4) photo engraving: this method is developed from the photographic plate making technology of printing industry.

The main process is to spray a layer of photosensitive glue on the surface of the copper roller to produce insoluble film after exposure.

After the color separation and photographic method, the pattern is made into positive prints of various patterns, exposing the positive ones to the copper roller coated with photosensitive glue, and the photosensitive glue at the non photosensitive spot can be washed with water, that is to say, the copper surface pattern.

Then the high temperature baking makes the photosensitive film solidified with acid resistance and insulation property. Finally, the flower pattern with concave pattern is made by chemical or electrolytic etching.

The pattern and pattern of photo engraving are adaptable, productive and reproducible.

(5) electronic engraving: electronic technology is used to control the graver and directly cut the concave pattern on the surface of the copper roller.

The basic process is to separate the patterns into black and white manuscripts on white paper, and then paste them on the roller of the electronic engraving machine with the black and white draft, so that the roller and the copper roller to be synchronized operate on the machine.

The optical signals generated by continuous photoelectric scanning of the black-and-white manuscript by the scanning head are converted into electrical signals. After amplification, the graver is controlled and chipped on the copper roller.

2 working principle and characteristics of electronic engraving machine

The general electronic engraving machine is composed of the original drums, engraving rollers, scanning, engraving, pmission systems and electrical cabinets.

At work, the scanning head enters the photomultiplier tube into the photomultiplier tube through the lens through the lens. The light intensity is converted to the corresponding strong and weak electrical signal, and is mixed with the number of the message. After the electromagnetic control system is controlled by the computer, the electrical signal is converted into mechanical action for carving.

The carving roller synchronously runs with the original cylinder, and the carving system moves along the axial direction of the drum.

The carving system is a sharp diamond knife controlled by the scanning system. It is carved on the copper surface of the engraving cylinder according to the signal strength, and the conical dots with different depths are carved into dot patterns.

The modern electronic carving mechanism printing roller does not need to input information through the scanning unit.

If input by digital camera, all image data, device drivers, parameters and other information will be digitally pmitted to the electronic engraving equipment.

The key technologies of the electric carving system include driving circuit technology, digital signal processor application technology, AC servo technology and high frequency electromagnet technology.

Compared with other plate making technologies, plate making costs are low, production efficiency is high, processing cycle is short, labor intensity is low, plate making quality is high, and it is suitable for carving moire patterns, and has stable performance, wide adaptability and environmental protection. Currently, it occupies a leading position in the printing roller plate making field.

2.1 unit electronic document processing, imposition and proofing.

Processing of 2.1.1 unit electronic documents

The printing pattern is first input to the computer by corresponding equipment, such as scanner or digital camera, and then processed by appropriate software, such as PHOTOSHOP, to produce the unit product.

Image processing includes image editing and processing: image editing refers to drawing dots, lines, polygonal lines, etc. in various ways, and has special drawing functions (such as mud points, skimming, dry pens, etc.), curve fitting, color substitution, line width selection, image continuous Quartet, laying arbitrary shading, image roaming, etc.

Image processing, such as smoothing, image enhancement, thinning and removing miscellaneous points, can also improve image skew and size adjustment.

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Color separation refers to the process of receiving, returning, changing, and acquiring monochromatic manuscripts on a computer.

(1) take a look back: as the sample is generally a small complete flower back (sometimes not very accurate), when the color separation film is made, it needs to be exposed to several times in vertical and horizontal directions to form a whole pattern. In the design of computer color separation, it is considered that the technology commonly used in flat 1/1, jumps (1/2, 1/3, 1/4) to go back to the way, and can automatically determine the minimum flower back.

(2) coloring: the coloring is to classify all kinds of colors in the pattern as original patterns.

The coloring process is to restore the original color to the original color. Since the sample is "cloth like" with cloth, variegated, wrinkle and poor color uniformity, the appearance of scanning into the computer is very complicated. After scanning processing, special color treatment is needed.

The system provides 256 sets of colors for users and is optional on the screen in the form of palette. Users can restore the pattern to the number of chromatic numbers of the original cloth through the operation of windows.

(3) modification and color separation: as the samples are variegated, and the color needs to be modified, the system provides more than 30 kinds of modifying tools, such as rubber (off color), scissors (cutting the edges of the pattern), rotating (rotating the flower in any angle plane), scaling (the size of the flower in the printing process), smoothing the edges (smoothing the boundaries of the color blocks and lines, or removing burrs), and so on, which can meet the needs of the modification and comprehensive treatment of various patterns.

If there are some printing processes such as pressing, borrowing, synthesizing, preventing white, and leaving blank, it can be used in the process of color separation using all expansion, partial expansion and other drawing tools to meet the requirements of the process.

2.1.2 imposition

After completing the production of the unit product, it is necessary to divide the unit product into a large version of the engraving document, that is, the engraving process, according to the requirements of the engraving roll.

In the first time, the files should be trimmed, and the general unit files should have a cutting mark. One of them can be used as a benchmark. We should pay attention to the width of the marking line. For the vector document, the edge or the center of the marking line should be specified.

Enter the cutting size after setting the benchmark.

For vector state files, we should keep the bleeding according to the requirement. In particular, we should keep at least 0.11mm bleeding edges to prevent the edges from leaving the edges or the dots to form edges.

After completing the imposition, it is necessary to place control marks on the assembled pages for post process control, mainly including overprint markings for controlling accurate overprinting, and for controlling cutting marks.

2.1.3 format proofing

The layout proofing is the check of the image quality, so that the final inspection and confirmation of the make-up work is accurate.

When engraving the plate, the layout proofing adopts digital proofing, such as inkjet printing, laser printing, allowing customers to judge the overall design scheme and color effect. When the customer confirms the manuscript, it can pmit the designed format to the electric carving shop.

2.2 making process of electronic engraving printing roller

2.2.1 canister preparation

The preparation of the canister is an important link, and its quality has a great influence on the quality of the plate making.

The material of the canister is generally copper zinc alloy (containing copper 97.5% to 98%, zinc 2% ~ 2.8%, containing less than 0.2%), and the hardness should reach 78 ~ 84HB.

In general, the circumference of the new flower tube is 4.2 to 446mm, the flower tube is hollow, the inner diameter of the two ends is different, the cone is large, and a large inner diameter is called a big head. A small inner diameter is a small head, and the flower barrel is mounted on the conical shaft of the pmission part, which is exactly coincided with the inner cavity of the flower barrel.

The length of the flower tube is different from the specifications, ranging from 915mm to 1500mm. It should be selected according to the width of the printed fabric, and is related to the working range of the printing machine, the components of the flower barrel, and the length of the scraper scraper.

Width of carving = width of cloth semi press +3 ~ 4cm

If the width of the carving is excessive, it will waste both the color and the lining. However, when the whole flower is printed or some of the patterns are arranged, the effective engraving width of the flower tube should be slightly smaller than the width of the cloth.

The circumference of the general flower tube is equal to the integral multiple of the upper and lower dimensions of the unit pattern. If there is any excess, it is necessary to use lathe lathe to go. The number of cars depends on the size of the flower barrel when carving, and the circumference of the flower barrel is reduced by 1.5 to 2.5mm once every time the flower barrel is used. The old vlaway can use the old pattern carving depth car to continue to use, and when the flower circle circumference reaches 350mm, it can no longer be used.

The number of repeated engraving of the general pattern on the circumference of the flower tube is called the return number.

The pattern of each type of flower pot is uniform, the error should not exceed 0.1mm, and the precise geometric figure is higher, otherwise it is easy to cause the flowers to be inaccurate.

After the flower car is ready, first use hand to repair the surface sand holes, then put them on the grinding machine, use medium coarse grindstone to water mill, and then use granulate, hard and hard stone water mill to make the flower barrel surface clean and well polished.

2.2.2 trial carving

According to the requirements of the original manuscript, before carving, the carving must be determined by the electric carving personnel, that is, the "ten" character line should be aligned, and the test value should be set in combination with the printed product.

Carving before carving is very necessary.

The role of test adjustment is to adjust the range of oscillation current, amplitude and baseline, so that the engraved dark tones, Gao Guang and ditches can meet the technological requirements.

The specific method of trial carving is to engrave short test engraving documents. It is a small drawing or parameter file specially designed for trial carving. It usually consists of several rows of high light points, several rows of real places and several lines of dots.

The arrangement is horizontal and vertical, generally shorter, with a length of 5 to 10mm.

After one trial, the height of the highlight, dark tone and through groove can be measured by net points. According to the foregoing rule, the corresponding current value should be adjusted, then the carving should be re tested, and then the measurement and adjustment will be made until the technological requirements are met.

After trial carving, the carving current is adjusted to the appropriate value, and the carving start position can be set and the official sculpture will be started.

2.2.3 engraving

In the entire carving process, the carving knife moves in a concussion way, and keeps a certain frequency of oscillation.

The frequency generator guarantees to provide a stable oscillating current. All movements include scanning roller (if there is), speed of the carving roller, scanning head (Ruo You), pverse feed speed of the carving head, etc., which are calculated and controlled on the basis of the oscillating current. On this basis, the rotational speed of the carving roller and the pverse feed of the carving head make the sharp diamond knives carving the net holes on the carving roller according to the signals, forming certain net lines and net corners, forming a printing pattern.

2.2.4 finishing

After finishing the cylinder, the following operations are required:

(cleaning cylinder (using pyruvic acid to wipe the cylinder) - electrolytic degreasing - cleaning activation - using (5% sulfuric acid) - chrome plating - cleaning (using 400# water sand friction steel roller).

2.2.5 points for attention

When carving the lubricating oil, we should pay attention to the following points: wear gloves when handling the rollers, avoid the sweat pollution on the surface of the roller; when the cart is to be carried, the liner should be wrapped in the contact parts of the car and the roller to prevent the roller from being rubbed in the process of pportation. When the roller is installed, the roller should be accidentally knocked down, and the machine or parts should be damaged. The large rollers that have difficulty in manual handling should be considered installing cranes or Longmen frames, and also using hydraulic cars. When choosing the carving oil, we should pay attention to the selection of engraving oil with good quality and control the dosage. Inferior or more engraving oil may result in premature aging of the rubber on the carving head and the service life of the carving head. (1) pay attention to the first cleaning of the page before carving.

(2) the relative position between the carving knife and the roller has great influence on the adjustment of the carving current.

The relative distance between the carving knife and the roller is controlled by adjusting the sliding foot or directly adjusting the carving knife.

The relative distance between the engraving knife and the roller is based on the electric current of the engraving head.

If the carving knife can not cut out the cutter line, it means that the carving knife is too far from the surface of the roller. It should slip back into the foot or enter the carving knife. If the cutter line is too thick, it means that the carving knife is too far from the surface of the roller, and should enter the sliding foot or the carving knife.

(3) when the same color plate has both text and electrical map or large field color block, if it can not be considered in the same line number angle, it will be solved by the method of fractional carving.

In many engraving operations, most of the methods are to complete the trial carving of all the engraving processes in advance, record or preserve the adjusted current value, and set the initial position of carving at a time.

When the engraving is finished, the next set current is input or pferred, and the new starting position is no longer reset to ensure that the position of multiple engraving remains unchanged.

Repeated engraving is a special method used in the case of a carving which can not meet the printing requirements. It can be engraved again on the net point for the first time by repeated engraving so as to increase the ink content of the mesh point.

(4) working environment: mainly refers to the changes of temperature, humidity and voltage in the working environment.

The temperature of the electric carving workshop is kept at 20 + 2 degrees, the humidity is maintained at 50% - 60% of relative humidity, and the fluctuation of voltage is not more than 10%.

(5) routine maintenance, according to the engraving machine instructions and actual operation conditions, carry out regular maintenance and maintenance of the sports parts.

2.3 development

With the progress of science and technology, the technology of electronic engraving and plate making is advancing with the times. Hyperfine carving technology has been published. Intelligent and high frequency carving technology is the main direction of development.

The engraving system is intelligent, including automatic carving, automatic crossing over non carving area, and automatic replacement of the system.

Carving frequency is the bottleneck that affects the efficiency of electric carving system. Therefore, developing electromagnetic engraving head with higher frequency has always been the main research direction of electric carving enterprise.

Through the development of electronic engraving technology, roller printing will continue to exert its high productivity, suitable for mass production, clear outline, fine outline, rich sense of hierarchy and low production cost, and will play a great role in fabric printing.