Curved screen printing process of the hottest pack

The curved surface printing process of packaging containers (Part 2) everyone knows and learns in detail

III. the printing process of rotating plastic containers

rotating plastic printing mainly refers to cups, bottles, cans, cylinders, etc., which have cylindrical, conical, elliptical and other shapes. The printing position can be one section on the front or two sections on the front and back, or it may be printed all over the circumference

Figure 2 printing of soft containers

printing of rotating plastic containers should be carried out on the equipment shown in Figure 2

. There is a rotary printing support in the center of the printing surface of the printing table, which is used for positioning the printing pieces. There is a conical plug pipe head at the rear of the support, which is consistent with the diameter of the container. The pipe head is connected with the compressed air pump, so that the soft plastic container can be inflated during printing, so that it has a force to counter the printing pressure. There is a set of backup rollers in the middle of the support that coincides with the outer diameter of the container, and the front end of the support has a chuck that coincides with the bottom of the container. The positioning pin on the chuck matches the positioning pin groove injected at the bottom of the container. When scraping the printing plate, the cone plug, backup roller and chuck are transferred at equal linear speed. After printing a plate, the locating pin of the chuck still returns to the locating point

when printing plastic containers, place the busbar of the substrate of the rotating part in a parallel state with the plane under the plate. During printing, the plate and the substrate always move in line contact, and a line rolling motion is formed between the plate and the substrate

1. cone printing and operation

(1) cone printing and plate making

cone printing plate making is different from cylinder printing plate making. The cylinder printing expanding surface is a straight plane pattern, while the cone printing expanding surface is a fan-shaped pattern, which is curved. Therefore, before cone printing and plate making, calculate the perimeter difference between the upper and lower circles of the cone and draw a sector diagram. A more accurate method is to imitate the patterns and words to be printed on the substrate, draw them on paper, make a fan-shaped map, cut them out and stick them on the cone, so that the version made is more accurate. Adjust the angle between the center line of the substrate and the horizontal direction according to the taper of the container to ensure the levelness of the printed surface of the substrate and the plate (generally within 8 °). During printing, the direction of the printing pressure of the scraper should pass through the center line of the substrate (see Figure 3)

Fig. 3 fan-shaped expansion diagram of conical objects

(2) adjustment of cone printing and printing machine position

cone printing is also different from cylinder printing. The plate printing cylinder substrate moves horizontally and linearly, while the plate printing cone substrate swings horizontally with the cone top as the center. Conical objects are big at one end and small at the other. When printing, first adjust the substrate placement support and substrate on the printing machine (see Figure 4) to be parallel to the plate, then adjust the swing radius of the plate movement, and print the conical substrate with a method similar to printing cylinder

Figure 4 conical printing structure $page break $

2. Ellipsoidal printing process ellipsoidal printing characteristics

ellipsoidal plastic containers are widely used, mostly for cleaning agents, shampoos, drugs, cosmetics and other packaging containers. Oval printing, as shown in Figure 5, takes o point as the center and R as the radius for circular motion. Therefore, the special printing fixture shown in Figure 6 is required. The rotation radius of the fixture is the radius of the large elliptical surface (printing surface), and the radius of the steel wire disc used for the rotation of the substrate is also the radius of the large elliptical surface. The ellipsoid printing method is different from other printing methods. Before printing the ellipsoid substrate, first make a fixture according to the overall dimensions of the ellipsoid, in order to clamp and fix the substrate on the substrate placement bracket of the printing machine, so that the bracket and the ellipsoid substrate rotate 180 ° synchronously during the printing process. In addition, the rotation degree should be adjusted according to the length of the printed pattern surface

Figure 5 elliptic printing

Figure 6 elliptic printing device

(2) ellipsoid printing and printing machine debugging

before printing, first clamp and fix the plate on the horizontal plane, then put the elliptic substrate into the fixture, and shake the substrate lifting bracket on the printing machine to the top with your hand, so that there is a certain gap (distance) between the substrate and the plate. Then adjust the pressure of the tongue U plate applied to the plate. It is required that the pressure is moderate, the round-trip travel is appropriate, and the ink return plate is also adjusted properly. Finally, manually rotate the printing machine as a whole, and adjust the coordination of various parts of the printing machine for the second time; After confirming the accuracy, start the machine for trial printing

IV. printing process of non rotating plastic containers made of graphene materials

after the plastic container is formed, the graphics and text can be directly printed with plastic ink, which can print monochrome and various colors. The process is simple and the cost is low. Modified polystyrene, high impact polystyrene, ABS plastic, plexiglass, etc. are mostly used in radio, tape recorder, television, household appliances and computer shells. In recent years, the plastic printing process of various domestic electronic products has been widely used

the key points of the printing process of non rotating plastic containers are as follows

(1) the handwriting and graphic edges of the original negative must be flat to reduce the jagged edges of the imprinted edges. The distance between handwriting strokes must be increased by about 0.1 mm than the actual effect to avoid errors caused by the natural leveling of ink

(2) direct photosensitive method mostly uses polyester yarn with more than 110 mesh/cm, because polyester yarn has high stability, which can improve the uniformity of the imprinted edge and reduce the deformation of the plate. The measured value of tension during tension should reach about 1.5 mm (mm tensiometer)

(3) use solvent resistant silk photosensitive adhesive or photosensitive film to make plates

(4) when printing special-shaped objects, make suitable

fixtures and special-shaped wire frames. For example, when printing curved containers with small radians (about 30 °), the stretched arc process can also be used without a curved printing machine

① prepare two wooden strips first and plane them into the required radian. The groove of the fixing wire is processed on the wooden frame, and the size in the frame is generally 3 times larger than the size of the printed pattern. After stretching with the driving method, L-shaped hardware accessories are installed around the wooden frame to prevent the frame from deformation, and the blade of the scraping plate should also be in a corresponding arc

② when the arc is exposed in plate making, it is necessary to approximately measure the fatigue curve and roughly estimate the fatigue limit. Note that the negative must be close to the wire

③ the prepared version must be fixed on the workbench with a hinge to prevent loosening and displacement during printing and blur the image

(5) correctly select the hardness of the scraper

(6) the release agent on the plastic should be removed before printing, and it is best to use fat solvents and alcohol solvents

(7) choose appropriate ink to form an ink film with good performance

(8) fully master the performance of the substrate, and correctly select the ink solvent, additives and pre press and post press processing technology

(9) when removing unqualified marks, deinking agent is generally used. It is suggested to use the following deinking agent formula: 2 parts of alcohol plus 1 part of tetrahydrofuran (volume ratio), which can be used after being stirred evenly, which can remove the printing ink from the steel coal and do not damage the surface of plastic products

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