The printing presses are manufactured to meet the requirements of the printing process. Different plate types have different requirements for printing presses. If the printing plate used for lithography, you should use offset printing presses to print, and lithography offset printing presses and letterpress or gravure printing presses compared to the obvious difference; if the printing plate is intaglio, the gravure printing press mechanism must be able to ensure the realization of strong printing pressure of the process requirements, Because gravure printing required printing pressure than letterpress printing presses, especially than version of offset printing presses are much larger. From this point of view, the printing process is characterized by the design, manufacture of printing presses of the main basis.
Printability has a great impact on the design, manufacture and use of printing presses. The so-called printability refers to the substrate, printing inks and other materials and printing conditions to match the overall performance of the printing operation. In addition to the printing suitability of the printed materials, in order to obtain good printability in printing, the structure of the printing press should be continuously improved.
The specific work requirements of the printing presses are reflected in the following points:
1. Working performance
The working performance of printing presses mainly includes three indexes such as overprint precision, ink color Shing and productivity.
① overprint Precision
In the process of chromatic printing, the accuracy of imprinting overlap is one of the main technical indexes of printing presses ' working performance. The same paper transmission, handover and printing, whether at low speed or high speed should be able to ensure that in the specified position. This requires the printing press transmission system, paper transfer location and time, as well as the printing plate and press the transmission precision of the mechanism should meet certain requirements. Therefore, when we analyze the printing press, we should focus on understanding and overprinter accuracy related to each link, grasp its characteristics and its role.
② Ink Color Shing
The ink-color Shing is the consistency of fingerprint ink layer thickness and the clarity of ink, which is also an important index to measure the quality of printing, and also an important content to evaluate the working performance of printing presses. No matter which kind of printing method, to print ink clarity strong printing, not only require ink color uniformity, but also need to have enough printing pressure, so require printing device, inking system, etc. should have high precision and performance.
The productivity of the printing presses is generally expressed in print speed. The representation of the speed of printing, for a sheet-fed printing press, expressed in sheets/hours; For web presses, expressed in meters/cents. The structural formation and characteristics of the printing press and the technical level of the automatic control system are the main factors determining the productivity. At present, the printing presses are developing to large-scale, high-speed and linkage, in order to maximize productivity.
2. Use Performance
① Operational Performance
In order to improve printing speed and automation of printing presses, it is also needed to ensure good operating performance. Printing presses generally occupy a large area, should set up a few sets of control disk to ensure that operators in every major work position can operate.
② Safe and reliable performance
In order to ensure the safety of personnel and equipment, in addition to the printing press on the safety device, but also have a safety protection device, but also have a safety device, once the machine failure can automatically stop.
It is important for the state and enterprises to require the printing press to maintain its original precision after long term use, that is, the machine has a long service life. To do this, we should choose the parts material and heat treatment process reasonably, in order to ensure the wear resistance of the parts, in order to improve the movement accuracy of the transmission system, each mating surface should have reasonable body shape precision and good coordination clearance and lubrication device.
3. Process Performance
The printing press satisfies the main work performance premise, should strive for its simple structure, compact, has the good processing craft, reduces the manufacture cost, facilitates the assembly and the maintenance. In the process of the use of printing presses, it is inevitable that dirt or toner scattered situation. In recent years, our country introduced from abroad dry Ice blasting machine (dry ice cleaning machine, dry ice ejector, dry ice jet cleaning machine, washing machine, mold cleaning machine) can remove some large equipment dirt, grease, ink, and the effect is significant, dry ice cleaning technology with its unique cleaning medium (dry ice) is widely used in many developed countries. Dry Ice Cleaning is the production of liquid CO2 through dry ice making machines (dry ice granulator, dry ice granulator, dry ice granulating machine, ice machine, dry ice machine) in 3mm diameter cylindrical granular dry ice. Dry ice pellets are powered by compressed air, and are sprayed to the surface of the cleaned material at higher speeds through a dry ice cleaner. Dry ice cleaning is characterized by fast speed. Dry ice is very volatile, it is impossible to slow operation, and stripping speed is high, so can achieve the purpose of rapid cleaning. Secondly dry ice cleaning belongs to "dry cleaning", does not produce any conductive medium, will not residual conductive medium and damage equipment. The main thing is that dry ice cleaning will not produce two of pollution, without the cleaning medium for recycling and processing, can significantly reduce costs.
These requirements are often restricted and contradictory. To improve the accuracy of overprinter, at high speed operation is not easy to achieve. Because of the further increase in printing speed, but also bring some new problems: the rapid and accurate transfer of paper and transmission, ink fast drying and moving parts of the smoothness will be greatly affected, so that overprinter accuracy is difficult to guarantee. If the control device is added, the manufacturing cost of the machine will be increased. Therefore, we can only take the above-mentioned requirements as the starting point of the analysis, according to the printing process of the machine requirements, grasp the main contradiction and weak links, from the overall balance, in the premise of meeting the major requirements, to properly resolve the secondary contradictions.