Offset printing 1000 questions (323-334)

323. What kind of printing machine?
A: Shaiban can be broadly divided into single-side printing machine, double-sided printing machine and continuous drying machine. In addition, there are linkage lines that combine printing, development, and gluing. Wait.

324. What are the structural features of a single-sided printing machine?
A: The single-sided printing machine is a representative model in the lithographic printing. It is composed of a printing rack, a drying frame (including a drying frame and a lower drying frame), an air extraction system, and a light source device.

325. What are the operating points of a single-sided printing machine?
Answer: 1 There are two manual and automatic operating methods and procedures for one-sided printing machine. First, you must select the operating mode and program.
2 Turn on the light source warm-up (except the fast-start light source) 5 minutes in advance to reach the rated power;
3 Pre-set automatic control data such as suction, main exposure, and secondary exposure;
4 After the end of the exposure, let go of the air and wait until the reading of the vacuum gauge pointer reaches zero.

326. What are the structural features of double-sided printing machine?
Answer: The double-sided printing machine is composed of a double sun frame, a cabinet, a light source device, a vacuum system, and an electrical control system.
The two drying frames on the double-sided printing machine can be flipped. When the sun frame below is exposed, the top frame can be opened to prepare for another plate. When the exposure of the sun frame is finished, the top frame can be flipped to the bottom for exposure. Stencil work can be carried out continuously.
The light source is completely enclosed in the box. Since the exposure process is performed under closed conditions, no change in the photosensitive layer is observed, and therefore, the performance requirements for the photosensitive material are relatively strict.

327. What is the operating point of the double-sided printing machine?
Answer: 1 After loading, you should first pump and then turn it over. It should be turned counterclockwise;
2 It is not advisable to adjust the control electric during the exposure process;
3 After the exposure is over, the sun frame should be flipped to the horizontal position, and the positioning pin should be locked to take the version.

328. What are the features and structural features of the dryer?
A: Even the main function of the dryer is to replace the manual gauge line, and the smaller original version can be used as a split printing plate or a full-open printing plate. The mechanical precision is high, and the printing is accurate, and the overprint quality can be improved.
Even the structure of the dryer is complicated, the latitude and longitude directions are moved by two handwheels respectively, and the size is displayed with a dial gauge, which is very accurate. Exposure is measured by a light meter that automatically controls the start and shutdown of the light, so the exposure time is accurate.
The new type of automatic dryer has high automation program, size, positioning, original movement, light source switch, exposure time control, etc. all controlled by the computer program, automatically completed.

329. What are the operating points of the dryer?
A: 1 Select the exposure mode, short-lived and pre-coated sensitized plates can use cold-colored light source, long-lived or instant-coated plates can use full-color light source;
2 Use the original size of the red base to make a shading frame, and then fix it on the original stand;
3 The plate is placed on the platen and fixed by suction;
4 determine the displacement method, the general continuous drying machine a total of 8 kinds of displacement;
5 determine the starting point, calculate the displacement size;
6 input exposure and extraction parameters;
After 7 days of drying, most of them also need to get rid of dirty cover plates, and perform secondary exposure in addition to dirty.

330. What is the characteristics of the print light source?
A: Shaiban light source refers to the light source that can cause physical and chemical reactions of the photosensitive layer in a short time during the printing process. There are many kinds of gas discharge used in the printing plate type light source, because the scattered light of the point light source is less, and it is convenient to use. It is the type of light source used more frequently on the printing machine.

331. What kind of light source?
A: The main light source of the printing plate is high pressure mercury lamp, carbon arc lamp, xenon lamp, xenon lamp and iodine lamp. At present, the commonly used printing plate source is a high-pressure mercury lamp and an iodine lamp.

332. How to choose the printing plate light source?
Answer: The selection of printing plate light source should follow the following principles:
1 Select according to the spectral sensitivity characteristics of the photosensitive layer;
2 Select the light source with a dispersive energy distribution in the range of 320-460nm;
3 Try to avoid using light sources with more heat radiation;
4 Select a light source with reasonable design and uniform illumination.

333. What are the specifications of the printing machine?
Answer: 1 The illumination uniformity on the work surface shall not be less than 85%;
2 repeat exposure time error does not exceed ± 5%;
3 The vacuum system can achieve 78kPa vacuum within 1 minute, can effectively adjust within the range of 0～85kPa, and the vacuum degree must not decrease by 20kPa after 5 minutes after closing the gas path. The deflation time should not be exceeded.

Over 2 seconds;
4Skiper glass double-sided flat, no scratches, no bubbles, etc.;
5 The machine can work normally when the power supply voltage fluctuates ±10%.
6 shading protection devices are available.

334. What is the function of the PS version of the development machine?
A: The PS version of the development machine is a development-specific device that can automatically perform development, washing, drying, etc. on the exposed PS plate. The currently used PS plate processor can automatically develop, wash, wipe, and dry the PS plate. It can also carry out automatic control of temperature and speed during the development process, as well as automatic circulation and replenishment of the developer.

----From "Printing Technology"