Adjustment of the transfer mechanism of the hottes

2022-08-09
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Adjustment of the paper transfer mechanism of the sheet fed offset press

the paper transfer mechanism is the key part of the sheet fed lithography press. If it is not adjusted properly, there will be some disadvantages, such as unstable movement of the paper transfer teeth, paper picking errors, different linear speeds, and so on, resulting in inaccurate overprinting. Therefore, it is very important to accurately adjust the paper delivery mechanism

the paper delivery mechanism of sheet fed offset press is generally an eccentric rotary paper delivery mechanism, and the paper delivery teeth swing by the swing cam through the four-bar mechanism. At the same time, the paper delivery tooth shaft is installed in an eccentric sleeve with an eccentric distance of 20mm and rotates at a uniform speed through gears. Therefore, the motion of the paper delivery tooth itself is a uniform rotation motion made by the swing center around the eccentric center. Its motion trajectory is a "water drop" shaped closed curve. Due to the use of rotary eccentricity, the swing center of the paper feeding tooth during the return journey is improved, so the stability and transmission accuracy of the paper feeding tooth can be improved. However, due to the increase of eccentric rotation movement, the movement of the paper delivery teeth is complicated, and it also increases the difficulty of adjustment

in order to improve the accuracy of transferring and handing over paper, strict requirements should be placed on the movement of the machine at each characteristic stage, especially the movement of the junction point

in order to improve the stability and precision of the paper feeding teeth, and avoid the vibration of the paper feeding teeth caused by cam machining errors, wear and vibration, it is required that the paper feeding teeth should be in a static state when the paper is taken in by the closed teeth. Therefore, the roller and oscillating cam should be in a relatively static state when the paper delivery teeth take out the paper. The specific adjustment method is to adjust the backup screw when the roller is moved to the lowest position of the swing cam, so that the gap between the roller and the swing cam is 0.03mm-0.05mm, so that the time when the paper delivery tooth stops on the backup is 27 ° of the corresponding corner of the embossing cylinder

due to the vibration caused by the high-speed operation of the machine, the paper delivery tooth is not stable when it just stops on the mountain, so it needs vibration reduction to buy paper. In addition, the front gauge must wait for the paper teeth to hold the paper before it can be transferred to the imprint cylinder, which also requires a short process. Therefore, the specific movement time of the paper speed mechanism should be reasonably allocated: the paper delivery teeth stop on the backer, at this time, the imprint cylinder rotates 17 ° closed teeth to take the paper, the paper delivery teeth close teeth and start to lift up through the 5 ° front gauge, and then start to transfer paper to the imprint cylinder through the 5 ° paper delivery teeth

when the swing center of the paper feeding teeth is at the moment when the vertical paper feeding table is on the line between the eccentric center and the midpoint of the mouth between the paper feeding teeth, the vertical upward splitting speed of the mouth is 0. At this time, the paper is in an instantaneous static state, which is the best time to take the paper. When adjusting, on the premise that the whole machine is at the zero position, run the machine to the mouth position of the fast paper teeth. When the paper teeth pad is at the lowest position from the paper teeth, the roller controlling the closing of the paper teeth disengages the rotary opening and closing teeth cam installed on the paper teeth shaft on the transmission side. Under the action of spring force, the paper teeth just close at this moving position, and the paper taking accuracy is the best. If the tooth pad is not in the lowest position when picking up the paper, the working surface of the tooth pad is not parallel to the table of the paper delivery tooth. In this way, picking up the paper tooth when closing the tooth will slightly lift up the mouth of the paper, and the front mouth of the paper will be bent when closing the tooth, which will cause paper picking errors

since the transfer teeth move at a variable speed, and the speed accelerates from zero to the surface speed of the impression cylinder, while the impression cylinder rotates at a uniform speed, the angle the transfer teeth swing is different from the angle the impression cylinder rotates during the transfer stage, so when the transfer teeth reach the junction point, the axis of the transfer teeth - the swing center has exceeded the central line between the transfer teeth and the impression cylinder, that is to say, When the paper delivery tooth sends the paper to the junction point, the included angle of the swing center and the center line of the eccentric gear of the paper delivery tooth and the center line of the eccentric sleeve and the embossing cylinder is 18 ° after fine measurement, which is the main basis for adjusting the connection between the paper delivery tooth and the embossing cylinder. Before handover, the linear speed of the paper delivery teeth should be greater than the surface of the embossing cylinder. The aircraft design requires that the aluminum material of the aircraft body structure should not only have high strength, but also have sufficient fracture toughness and good fatigue resistance. The maximum linear speed is about 10% higher than the surface linear speed of the embossing cylinder, and then it will be reduced to the same speed of handover

in order to ensure the accuracy of paper handover and the accuracy of overprinting at the junction point, the floss speed of the paper delivery tooth and the impression cylinder should be equal and opposite when they are handed over to each other. In addition, during the handover process, the paper cannot be emptied. The paper teeth and the teeth of the embossing cylinder hold the paper together and run synchronously for 2-5mm. The tip of the paper teeth avoids the edge of the embossing cylinder. The increase in output means that we can reduce the market cost by 0 Mm, the lowest position of the paper feeding tooth pad is 0.3mm away from the surface of the embossing cylinder and 0 The results are processed and printed 3mm

in addition, the paper feeding teeth should hold the paper no less than 8mm, and the pressure of holding the paper should be consistent, and the height of the tooth pad should be consistent. In this way, the overprint accuracy can be ensured

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