How screen printing presses work

I. Working principle of flat screen printing machine

Taking the common flat screen printing machine as an example, the working principle of screen printing machine can be described as follows.

Scraping plate extrusion ink in motion and silk screen printing, silk screen printing plate and the substrates to form a stamping line, N1 and N2, because the screen has tension force F2 scraping board, for back to stretch the silk screen plate except the embossed line is not in contact with substrates, inks in scraping plate under the action of the extrusion of F1, through the mesh, from the movement of the stamping line printing on substrates.In the process of printing, the screen plate moves relative to the squeegee plate, and the extrusion pressure F1 and elastic force F2 also move synchronously. Under the action of elastic force, the screen returns to the contact point of the substrate in time, so as not to stain the impression.After the completion of unidirectional printing, the squeegees are separated from the substrate together with the screen plate and returned to ink at the same time, that is, a printing cycle is completed.

In manual printing, the operator’s skill and proficiency directly affect the formation of the impression line.In practice, screen printers have accumulated a lot of valuable experience, which can be summarized as six points, namely, to ensure the linearity, uniform velocity, equiangular, uniform pressure, neutral and vertical edge in the movement of the ink scraper.That is to say, the squeegees should move in a straight line without swaying from side to side.Not in front of slow after fast, fast after slow or slow;The inclination Angle of the scraping board should remain unchanged, especially to pay attention to overcome the common problem of the gradual increase of the inclination Angle;Printing pressure should be uniform and consistent;Keep the distance between the scraping plate and the inside side of the screen frame equal;The ink scraper remains perpendicular to the frame.

Two, flat screen surface screen printing machine working principle

Flat screen surface screen printing is used in cylindrical or conical surface screen printing.Under certain conditions can also be oval surface, drum surface, cambered surface and other surface screen printing.

When printing, the plane screen plate and substrate motion, while the scraping plate static.Plane screen plate clamped on the screen frame driven by screen printing machine with flat screen surface uniform translation, due to the screen plate friction placed on the supporting device of the substrate rotation.The linear velocity of the surface substrate at the embossing line is consistent with the moving velocity of the plane screen plate to realize the scraping printing.

Theoretically, the embossment line should be at the highest bus of the surface substrate to increase the off-screen Angle and ensure the printing quality.For the convenience of adjustment, the scraping board generally adopts 60° and 15° top Angle, which requires the vertical degree and upper and lower dimensions to be adjusted.Adjusted to the vertical

Straight is to ensure that the cutting edge line does not produce transverse shift when adjusting up and down, always aligned with the highest bus A;The scraper with a top Angle of 60° and 15° is adopted to ensure that the inclination Angle of the scraper is formed after vertical installation.In the actual adjustment, in order to ensure that the plane screen printing plate and surface substrate timely separated, the line can be appropriately offset a little, especially when the substrate diameter is large, the line must be offset.

The supporting device for surface printing is a special device of various forms, which is designed and manufactured by the user according to the product requirements.Two pairs of roller bearings can be used for surface printing of cylindrical containers or conical containers. Bushing supports can be used for caps and cups whose ratio of length to diameter is less than 1.5.The elliptic surface is approximately a part of the cylinder, and can be inlaid with a cylinder.

The principle of printing on the surface of a cone is basically the same as that of printing on the surface of a cylinder, except for the graphic shape of the screen and the motion of the screen.When making the screen printing plate used for printing on the surface of the cone, it is necessary to draw the expansion diagram of the surface of the cone, and according to the expansion diagram to find out the center o of the sector, and then select the appropriate screen frame to make the screen printing plate.Fan-matching plates can be made on FHG plates that can fully accommodate fan-shaped ABCD.Fix the right Angle lever on the efHG version and install the O axis to make the fan-rotating version.Then as the surface of the cylinder printing, at the bottom of the plate with four roller support substrate, scraper is fixed, according to the sector to move the plate frame, scraper pressure can be conical plate surface printing.During printing, conical bearing printing is in line contact with screen plate under constant pressure of scraper.When the screen plate moves horizontally around the axis of the fan diagram, the substrate rotates synchronously on the support device.The ink squeezes under the squeezer and leaks to the surface of the substrate to complete the printing.