Three requirements for evaluating the performance

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Three requirements for evaluating the performance of printing machines

in order to correctly evaluate the printing machine, the printing machine manufacturers and users put forward the following three work requirements for the printing machine

I. working performance of the printing press

correct evaluation of the working performance of the printing press mainly includes three indicators: overprint accuracy, ink uniformity and productivity

① overprint accuracy

it is of great theoretical significance to contain building flashover.

in the process of overprint printing, the accuracy of imprint overlap is one of the main technical indicators of the working performance of the printing machine. In the process of chromatic printing, the transfer, handover and printing of paper shall be ensured to be in the specified position at either low speed or high speed. This is even more important for fine prints and color printing. This requires that the transmission system of the printing press, the transfer position and time of the paper, and the transmission accuracy of the printing plate and imprinting mechanism should meet certain requirements. Therefore, when we analyze the printing press, we should focus on understanding each link related to overprint accuracy, and grasp its characteristics and its role

② ink uniformity

ink uniformity refers to the consistency of ink layer thickness and the clarity of ink, which is another indicator to measure print quality and an important content to evaluate the working performance of printing machines. No matter which printing method is adopted, printing with clear and firm ink color requires not only uniform ink color, but also sufficient printing pressure, which requires that the printing device, including the inking system, should have high precision and performance

③ productivity

the productivity of a printing machine is generally expressed in terms of printing speed. The expression of printing speed is expressed in sheet/hour for a sheet fed printer; For web press, it is expressed in m/min. The structure and characteristics of the printing press and the technical level of the automatic control system are the main factors that determine the productivity. For example, the platen press adopts an embossing cylinder, which significantly improves the printing speed compared with the platen press. However, the reciprocating motion of its platen limits the further improvement of productivity. Therefore, it is gradually replaced by the circular press. At present, the printing press is developing in the direction of large-scale, high-speed and linkage to maximize productivity

II. Use performance of printing press

the use performance of printing press mainly includes operation performance, safety and reliability performance and durability performance

① operating performance

while improving the printing speed and automation of the printing machine, it is also necessary to ensure good operating performance

generally, the printing machine covers a large area, and several sets of control panels shall be set to ensure that the operator can operate at each main working position. Each operating vertical plate shall conform to people's action habits, the working position shall be easy to observe, and the adjustment part shall be intuitive and easy to contact

② safe and reliable performance

in order to ensure the safety of operators and equipment, in addition to the absence of safety protection devices, the printing machine should also be equipped with safety protection devices. In addition, it should also be equipped with safety protection devices. Once the machine breaks down, it can stop automatically

③ durability

it is required that the printing machine can maintain its original accuracy after long-term use, that is, the machine has a long service life, which is of great economic significance to the country and enterprises. To achieve this, parts materials and heat treatment process should be reasonably selected to ensure the wear resistance of parts; In order to improve the motion accuracy of the transmission system, each fitting surface shall have a reasonable shape of several bodies. 2. Wood pulp and finished paper: the main wood pulp varieties currently have a 5% tax rate, good fitting clearance and lubrication devices

III. process performance of the printing press

on the premise that the printing press meets the main working performance, it should strive to have a simple and compact structure, have good processing technology, reduce manufacturing costs, and facilitate assembly and maintenance

the above requirements often restrict and contradict each other. For example, to improve the overprint accuracy, it is not easy to achieve at high speed. The further improvement of printing speed will bring some new problems: the rapid and accurate transfer and transmission of paper, the quick drying of ink and the stability of moving parts will be greatly affected, making it difficult to ensure the overprint accuracy. If the control device is added, the manufacturing cost of the machine will be increased. For another example, there are certain contradictions between simple structure and improved automation, and between printing speed and service life. Therefore, we can only take the above requirements, together with economic construction, political construction, cultural construction and social construction, as the starting point for analyzing the problem. According to the requirements of the printing process for the machine, we should grasp the main contradictions and weak links, balance the weight from the overall point of view, and properly solve the secondary contradictions on the premise of meeting the main requirements. This is also the thinking method that should be followed in the research and design of printing press

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