Knowledge collection of the hottest offset press m

2022-09-19
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Knowledge collection of offset press mechanism

11 Adjustment of paper feeding part

(1) benchmark. The starting point of all actions and behaviors. There is only one starting point, which is called absolute benchmark. For a machine, the machine benchmark includes design benchmark, processing benchmark, installation and debugging benchmark. Relative benchmark: this action and behavior takes absolute benchmark as the starting point, but it is also the starting point of other actions and behaviors. This starting point is called relative benchmark. Generally, there are more than one relative benchmark, but I hope it can help you. Their status is not equal

without benchmarks, there is no starting point for actions and behaviors, so all actions and behaviors must be in chaos. Therefore, when designing, processing, installing and debugging the machine, we must find its benchmark and relative benchmark, otherwise the machine cannot be manufactured

(2) commissioning reference. There is only one datum for the starting point of time and displacement of all parts of the machine, which is called the absolute datum of machine adjustment

in addition to the absolute benchmark, there is also the relative benchmark of the shunting machine, which means that the time and displacement of a certain part take the absolute benchmark of the shunting machine as the starting point, but some other parts take the time and displacement of the part as the starting point, so this part is called the relative benchmark of the shunting machine. Generally, there is more than one relative benchmark for machine adjustment

absolutely the State Council decided to establish a national leading group for the development of new materials industry (hereinafter referred to as the leading group). The benchmark and relative benchmark are the basis for machine adjustment. If the benchmark and relative benchmark cannot be found, the adjustment cannot be carried out. Mastering the absolute benchmark and relative benchmark can reduce the blindness in debugging, which is also one of the so-called shortcuts to machine adjustment

(3) the absolute reference and relative reference of printer adjustment the adjustment reference of printer varies with different models, but there is only one absolute reference of adjustment. The absolute benchmark for some machine debugging is the embossing cylinder, and some are the registration cylinder. At present, the absolute benchmark of multi-color printing machine adjustment is the registration cylinder (the paper delivery tooth is regarded as a part of the registration cylinder). It doesn't matter which absolute benchmark to choose for the adjustment, but once it is selected, it can't be changed halfway, otherwise all work needs to start from scratch. In other words, the absolute benchmark is not adjustable. The relative datum depends on the drive chain

(4) the time and displacement of each component of the transmission chain are linked in a certain order, and this chain is called the transmission chain. The non adjustable point on the transmission chain is the absolute benchmark of the adjustment machine. The microcomputer controlled electronic universal experimental machine of the transmission chain is your better choice. Except for the absolute benchmark and the last point of each branch (there are sometimes many branches in the transmission chain except the main chain), all other points can be called relative benchmarks

therefore, when debugging the machine, first analyze its transmission chain clearly, and then find the color pair benchmark and relative benchmark on the transmission chain. In addition, there must be a diagram of the time and displacement of each component relative to the absolute reference and the relative reference, so that there can be rules to follow when adjusting the machine. This is the most basic method of machine adjustment, also known as the principle of machine adjustment

(5) transmission chain of the paper feeding part the transmission chain of the paper feeding part is as follows:

registration roller - regular part - paperboard feeding - Feida - paper feeding pile

on this transmission chain, the registration roller is the absolute benchmark of the machine, except for the paper pile, others can be called the relative benchmark of the machine, but the position of these relative benchmarks is different. The closer they are to the absolute benchmark, the higher their level is, and others are second, According to the distance relationship with absolute datum, it can be divided into first, second,... Relative datum. Here, the rule part is the first relative benchmark, the cardboard conveyor is the second relative benchmark, and Feida is the third relative benchmark. The absolute reference and relative reference of the paper feeding part are found, and then the relationship diagram of time and displacement between each part and the reference and relative reference is prepared, then the paper feeding part can be adjusted. The specific methods are briefly described as follows:

① take the registration roller as the benchmark, and once its position is determined, it cannot be adjusted relative to any other parts

② the regular part is adjusted relative to the registration roller (or paper feeding tooth): when the registration roller takes paper from the paper feeding board, if the paper taking time is wrong, then only the regular part can be adjusted, and the registration roller (paper feeding tooth) cannot be adjusted

the cooperation relationship between the registration roller and the rule is as follows: when the registration roller takes the paper from the paper feeding conveyor, the rule part has been positioned. After the paper feeding teeth and the rule part are handed over for a period of time, the front rule is laid down, the paper feeding teeth take the paper away from the paper feeding board, and then the front rule returns to the paper feeding board to position the subsequent paper. After the paper feeding teeth are placed back, they begin to take the second paper. ③ Adjustment of the feeding board relative to the rule part: when the front rule just reaches the feeding board, the front mouth of the paper passed by the feeding board should be about 5mm away from the front rule. Why leave 5mm? The main consideration is the stability time of the front gauge, because the swing of the front gauge is driven by the cam. The front gauge stops on the paperboard, which is exactly the highest point of the cam in contact with the swing rod mechanism. This is a filtering point of the cam. Due to the inertia of the front gauge, the front gauge cannot be in an absolute static state at this point, so the front gauge needs a stability time. It was once believed that 5mm was used for paper deceleration, which was incorrect. Because the distance between the feeding board and the front gauge is always a fixed value, and the feeding board is always running at a continuous and uniform speed, the speed of the paper is the same every time it is transferred to the front gauge board. Assuming that the speed of the machine does not change, the way to slow down is to increase the displacement, but in fact, the travel of the paper on the front gauge plate does not increase due to that 5mm, so how can we say that it plays a role in slowing down? From another point of view, if the 5mm distance plays a role of deceleration, then the 5mm distance should also change with the change of the speed of the machine, with a higher speed and a larger distance; Lower the speed and distance. This assumption does not exist at all

how to ensure this 5mm distance? The only way is to adjust the fit between the board conveyor and the front gauge. This adjustment place is generally on the transmission surface of the paper feeder, and the relationship between them is changed through the position change of gears or chains, so as to meet the predetermined requirements

④ adjustment of Feida relative to the paperboard: during normal operation, Feida should transfer the paper through the paper receiving roller for about 5mm, and then the pressing wheel can be pressed down. If this cooperation is found to be incorrect, Feida should be adjusted. At present, the Feida of the film machine is generally driven by the universal joint shaft by changing the position of the long hole on the flange at the end of the universal joint

⑤ the adjustment of the paper stack relative to Feida: when the paper stack and Feida are not suitable, the paper stack should be adjusted first, that is, the paper stack should be in a free state

the adjustment between the paper feeding parts is briefly described above, and the internal of each part can also be adjusted according to this relationship, but one thing to note is that it must not be reversed, that is, the benchmark cannot be reversed

the relatively complex components are Feida and rules. The rules have been described before. Next, take Feida as an example to analyze the internal adjustment methods of components. The relative motion relationship of the components in the fedda has been fixed in the design, and it is generally not adjustable. It can only be adjusted during overhaul, but it is very beneficial to analyze the relationship between its internal components here. Paper delivery suction nozzle and paper separation suction this material was originally developed for the furniture industry. The role of the nozzle and presser foot has been described previously. From the perspective of the transmission chain, the relationship between them should be: paper delivery suction nozzle, paper suction nozzle - presser foot. The paper feeding suction nozzle is the absolute benchmark for fly-in-flight debugging. The paper separating suction can only be adjusted relative to the paper feeding suction nozzle, but relative to the presser foot, it is also the relative benchmark. That is to say, when the matching between the paper delivery suction nozzle and the paper separation suction nozzle is incorrect, the paper separation suction nozzle should be adjusted; When the relationship between the paper separation nozzle and the presser foot is incorrect, the presser foot should be adjusted. This clarifies the relationship between the three components

(6) the application of the symmetry principle in the adjustment of the paper feeding part. From Feida, the paper feeding board to the front gauge, it can be seen that most of the components on it appear in a symmetrical state. For this reason, the adjustment of these components must be based on the principle of symmetry, that is, position symmetry, force symmetry and adjustment symmetry. This is the key to ensure the normal operation of the machine. But in the actual process, the ideal symmetry does not exist, so will the normal operation be destroyed? Actually not. Why? This is because the rule part can make up for the paper feeding error. In fact, it makes up for the error caused by these asymmetric factors. However, the error that can be compensated for is limited. When the paper feeding error exceeds a certain degree, the rules can do nothing but give an error signal. The only way to solve this problem is to adopt the principle of quasi symmetry. In practical work, all components should work in the state of quasi symmetry principle, and make it close to the ideal symmetry state as much as possible, which is one of the primary conditions for machine adjustment

Author: Cai Jifei

source: offset collar machine must read

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