③The disassembly and assembly of printing machine.
The repairmen repairing the printing machine faces the problem of disassembly and assembly, especially assemble, which may directly influence the property of machine. If the assembly quality is not good, it may lead to serious wear and tear of the machine.
a) The disassembly of machine.
Due to the various types of printing machine and the various shapes of the parts, we have difficulty in introducing them one by one; here we will introduce the general principle ofdisassembly.
First, we must get to know the structure, function and principle of the machine and refer to related technical information and instruction book. We must be practical, determine disengaging section, and try to keep the parts that do not need disassembly. And for parts that do not need disassembly, we must first have an overall check to ensure the quality.
Second, during the disassembly we must proceed from the outside to the inside, first disassemble the accessories and oil pipes on the outside, and for parts of relative importance, we must mark them during disassembly and avoid disordered pile up. Reasonable use of the tools is also important and the tool must go with the parts to be disassembled. For example, when disassembling screw adapting piece, we must use proper wrench and when disassembling staticfitting piece, special tools must be used. No false hammering and prying is allowed.
Besides, we should create conditions for the assembly during the disassembly, for parts that are not interchangeable, better mark them or put them in pairs for the purpose of resetting during the assembly. By doing this, we can assure the assembly precision and avoid unnecessary wear and tear.
b) The assembly of the machine
During the assembly, we must guarantee the matching precision and dimensional accuracy. To ensure the matching precision, we can adopt trial and error procedure, fitting method and the adjusting method. Dimensional accuracymainly refers to assemble the size of each part of assembly error degree, that is to say, in the assembly, we should pay attention to eliminating accumulative error, and avoid bad influence to the machine due to the increase of the accumulative error.
Sealing is also very important during assembly. In the printing machine, sealing is mainly used in positions such as the air pump, gear case. In case of ineffective sealing, air and oil leakage may occur. Therefore, in the repair the sealing material must chosen be suitable, the assembly must be reasonable. Choose liquid sealed plastic for static sealing deposit. According to the different nature of use, we adopt dry attachment type, dry peelable type, the dry sticky type and half dry viscoelastic type.
We must not ignore the preparation work before the assembly, which includes the inspection before the assembly, the cleaning during the assembly and theassembling of component elements. Lastly, the test runs after the assembly. Its function is as follows: number one, check the quality of the assembly; number two, adjust the machine.
c) The cleaning of machine elements
The cleaning of machine elements is an indispensable part of machine maintenance and the major content of cleaning is to oil removing and rust cleaning.
The methods of oil removing mainly include removing with aqueous alkali, organic solvent and metal detergent. Aqueous alkali refers to the solution withemulsifiers, which is a good choice for cleaning mineral oil. The so-called organic solvent generally refers to gasoline and kerosene, which could dissolve all kinds of oil, do not harm parts. Apart from gasoline and kerosene, for small parts and adhesive parts of high precision, we can choose organic solvents such as alcohol, acetone diethyl ether. Metal detergent is a kind of newsynthetic detergent and due to the fact that the surface-active substance decrease interfacial tension, effects such as humidification, seepage, emulsification and dispersion occur, thus having super strong dirt-removing power. This kind of cleaning agent is non-toxic, non-corrosive, incombustible, not explosive, non polluted and is anti-rust and cheap, so it is widely used.
The methods of rust cleaning are mainly mechanical and chemical. Mechanical derusting usually uses a wire brush,scraping knife, abrasive cloth, motor-driven grinding wheel or a wire wheel. Chemical derusting usually use hydrochloric acid, sulfuric acid and phosphoric acid to remove alkalinous metallic oxide, which is easy and of good effect. When derusting with this method, be sure to know well the different ratios of the solvent.
The development tendency of printing equipments
In the future, printing equipments will be more intelligentized with less non-cutting time; Electrical equipment system integration; modularization of products and the products will be multi-functional; stable and reliable quality and more environmental-friendly.
In different fields of the printing equipment industry, the potential of increase and profit vary. The market driving forces that promote the development of the printing equipment industry change along with the times, for example the degree of market competition and the diversity of customers. In the past few years, the application of the digital computer to plate technology surpassed the conventional simulation technique .This trend will continue as more small and medium-sized printing enterprises realize the digital pre-presstechnology.
On the other hand, the high demand for presswork and the growing capacity of quick printing shops will attract more investment in the print media industry. Though the internet, TV, advertisement and other modes of transmission develops continuously, print media still occupies a dominant position in the advertising industry. Corrugated board, solid packing and printing flexible packaging carton printing label printing together form the largest share of the final printing market. Apart from packaging, magazines, newspaper, catalogue, books, brochure, direct mail, commercial form and office printing together form the remaining share of the final printing market.
In the past ten years, digital printing has snapped most of the market share from traditional sheetfed offset printing and if during the financial times the digital printing still prospers.
Currently there is a trend of cost control, reducing the profits and price pressure, the integration of the industry will still continue.
The year 2008 and 2009 are undoubtedly the most difficult time in the history of the global printing industry. Both the printing service providers and the equipment suppliers face unprecedented challenges. During this period of time, the sales of the printing equipment dropped by 7%-8%. A great many implemented a series of plan to get through the gravest recession in the history of the printing industry and as a result they survived. However, online printing and other digital printing methods experienced growth, which aggravated the existing crisis of the printing industry. Many big equipment manufacturers went bankrupt; some small-scale companies either cooperated with other companies or got merged by big enterprises in the industry. The income indicator of industries such as the sheet-fed offset press , business Web device and the newspapering has dropped to the lowest level.
However, as the global economy grows better, the first half of the year 2010 saw the growth of the global printing industry. The need for sheet-fed press and commercial rotary press gradually increase and it’s expected that they will go back to the former development speed.
At present, Europe is the largest regional market for printing equipment and service. The US and the Asia- pacific region are the other major market. Under the push of markets such as Australia, China, India, Singapore and Thailand, the market need in the Asia- pacific region expanded rapidly. It’s expected that by the year 2015 it will keep growing, among which sheet-fed press will keep the fastest compound growth rate between 2007 and 2015.
