Prospect of the application of the hottest electro

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Prospects for the application of electronic cams in printing machines

at the 6th Beijing International Printing Technology Exhibition in May 2005, many internationally renowned printing machine manufacturing enterprises (Heidelberg, Roland, Komori, etc.) and many domestic printing presses brought their newly developed technical products. Based on the current development of printing machines, it can be seen that the mechanical part of traditional offset printing machines and gravure printing machines has not been improved much, and most manufacturers focus on the electrical automation of printing machines. Heidelberg company, for example, focused on the advanced printing machine control technology such as its Yintong CP2000 control center at the exhibition. In addition, since Mannesmann company of Germany developed the shaftless technology of replacing the long axis of the unit type printing machine with servo motor group, that is, to ensure the synchronization between the units and rollers through electrical control, this technology has been rapidly promoted in the printing machine industry. Through this exhibition, we are glad to see that many enterprises have used shaftless technology in their printing machines, such as the 60A web lithography medium-sized newspaper printer produced by beiren Co., Ltd. Moreover, through relevant information, we also learned that after beiren Co., Ltd., Shanghai Gauss and other large domestic printing machine manufacturers launched printing machines using shaftless technology, Shaanxi beiren printing machine Co., Ltd. and Zhongshan Songde Packaging Machinery Co., Ltd. launched shaftless drive drum paper gravure printing machines, and Wuxi Baonan printing machine manufacturing Co., Ltd. also launched small drum printing machines using shaftless technology. Some foreign models also use shaftless Feida to improve production efficiency and avoid machine failure, such as libida 185/205 of gaobao company. It can be seen that the improvement of electrical control level has been a main direction for the development of traditional printing machines and the improvement of working performance

I. electronic cam

as we all know, cam is essential for printing machine. The design and processing difficulty of the cam is indeed that both Britain and Germany judge the flame retardancy of the external wall external insulation system through the model fire experiment. The printing speed of domestic printing machines always hovers below 8000 sheets/hour, a large part of which is due to the deterioration of the dynamic performance of machine related parts under high-speed conditions caused by the cam mechanism, so the mechanical cam has always been a difficult problem for the printing machine manufacturing industry. The emergence of electronic cams has brought us hope

electronic cam simulates the function of mechanical cam by controlling servo motor through controller

the structure of electronic cam is doomed to have many advantages over mechanical cam. The use of electronic cam improves the control accuracy of the machine, increases the control distance, reduces the failure rate and improves the reliability; It simplifies the mechanism, makes the mechanism more flexible, and makes debugging and maintenance simple. The electronic cam uses software to control the signal, and changing the program can change the output law of the control signal, and then change the process. If the controller of the electronic cam is improved and the sensor with higher accuracy is adopted, the number of switches can be increased, and the on-off time of the output point can be set arbitrarily, so that it can become an electronic cam with strong versatility in many occasions. All electronic convex magnetic core material tensile testing machines are widely used in the research and development and production of high molecular materials. Enterprise wheels have the following common characteristics:

1 Compact design and few wiring. The electronic cam is composed of a controller, a position sensor (rotary encoder) and a connecting cable. When in use, the controller is installed in the electrical cabinet, and the position sensor is installed on the rotating shaft. The sensor and controller are connected by a cable, which is convenient and fast to use

2. Simple angle setting. The setting value of the on/off position can be determined by directly entering the angle value, or can be specified by the manual function; However, it is difficult to adjust the angle in the mechanical cam

3. Durable sensors. The sensor can withstand vibration, impact, harsh temperature, oil, dust and other factory environments

in view of the many advantages of the above electronic cams, the advanced technology of electronic cams has been adopted in many industries. For example, electronic cams are used in the improvement of spinning frames in the textile industry. After adopting the electronic cam technology, the traditional spinning forming process is changed. According to the requirements of users' spinning varieties, the spinning forming can be changed arbitrarily through parameter setting to meet the needs of new product development. The mechanical structure is simplified, the production efficiency of the machine is improved, and the consumption is reduced

in the printing and packaging industry, electronic cams have also been gradually applied. The mw1050a high-speed automatic die cutting machine of Shanghai Yahua company is monitored and displayed by PLC programmable controller and electronic cam divider, which makes the control and fault diagnosis of the machine extremely convenient. Moreover, because the servo is used to make the material testing machine continue to drive the standard tensile samples at the speed specified in gb/t228 (2) 002 standard, its characteristics of high speed, high precision and high response greatly improve the production speed. The maximum production speed of traditional equipment is usually 80 sheets/minute, but this system can double the production speed of the equipment to 160 sheets/minute. The closed-loop design and rapid response ability of this system enable the equipment to maintain extremely high control accuracy under high-speed production, and the overprint deviation is ≤± (0.3 ~ 0.5) mm (depending on the mechanical condition)

now many foreign companies develop electronic cams as their main controller products, such as fc21 programmable electronic cam switches for corner detection and control, which are generally produced by Japan Guangyang company with excellent alloy structural steel. This provides technical support for the application of electronic cams in machinery and equipment in the printing industry. For the printing machine with a large proportion of mechanical cam mechanism, the use of electronic cam to transform the traditional mechanical cam structure will undoubtedly bring great help to improve the performance of the printing machine

II. Improvement of constant force mechanism cam of offset press

we know that the large tension spring of the transfer tooth mechanism of offset press is used to overcome and balance the inertia of the swing process of the transfer tooth, which makes the roller of the connecting rod mechanism always close to the transfer tooth cam, so as to maintain the force closed and strict movement relationship and prevent impact. As the paper delivery tooth shaft rotates around the eccentric center, the paper delivery tooth is controlled by the cam and connecting rod mechanism to make a swing motion, which is fixed on the hanging spring movable pin shaft at both ends of the paper delivery shaft, and its position changes constantly in the process of movement. As a result, in addition to the original pre stretching, the stretching length of the large tension spring is constantly changing during the working process. When the paper feeding tooth swings to two limit positions, its maximum tensile change reaches 110 mm, which produces uneven load, which is detrimental to the dynamic performance of the paper feeding tooth mechanism. At the same time, due to the frequent deformation of the spring, it exceeds the fatigue strength and breaks prematurely. J2101, which has been eliminated, will cause frequent failure of the large tension spring when used, which will bring a lot of inconvenience to users. Therefore, in the later improvement (such as J2108 machine), a set of tracking cam and swing rod mechanism is specially designed to keep the stretching length of the large tension spring constant during the whole movement of the paper feeding tooth, which is the constant force mechanism. Through the principle and function of constant force mechanism, we can understand that the tracking cam is the core of constant force mechanism, but there are many problems due to the limitations of its mechanical structure. Take the constant force mechanism of j2203 and J2108 offset press for example. The force on the constant force cam is uneven, and the drum has impact in each working cycle, so the keyway of the constant force cam hub is particularly easy to shake. Generally, the keyway of the cam hub will shake within two years. In addition, we know that the quality of cam contour curve design and machining and assembly accuracy are directly related to the size of noise and vibration. At the same time, due to the limitation of processing capacity, it is difficult to obtain a perfect contour curve, so the force on the large tension spring is difficult to ensure constant, only small changes can be guaranteed, and it is difficult to achieve the desired effect. If the electronic cam is used to replace the traditional mechanical cam, these problems can be solved correspondingly, and the structure is simple, which reduces the machining cost

it can be clearly seen from Figure 2 that the original mechanical cam and many related parts are missing, and a servo motor appears instead. The mechanical structure is greatly simplified, and the reliability of the corresponding mechanism can also be improved. To sum up, we can predict that the application of electronic cams in printing machines will be more and more extensive. This will undoubtedly bring opportunities for China's printing machine manufacturing industry to improve product quality and catch up with and surpass the product level of foreign counterparts. ※

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