High-speed double-sided printing press

Vibration and noise are two important indicators that affect the machine performance, affecting the machine's accuracy and service life, but also affecting the operator's health. Therefore, controlling the vibration and noise of equipment within a certain range is a problem that must be considered in design and production. Vibration and noise are caused by the sudden change of the machine's operating speed causing the acceleration curve to be discontinuous or non-smooth and caused by sudden changes. Therefore, when designing moving parts, especially parts with a large change in design speed, attention should be paid to the rationality of acceleration. The opening and closing mechanism in a sheet-fed printing press is a typical mechanism of rapid change. The opening and closing of the dental curve is reasonable or not, which directly affects the working performance of this mechanism.

The double-sided double-sided monochrome lithographic printing press produced by Henan Xinji is a new type of high-speed double-sided printing press. During the trial production and rolling of the car in 1998, the vibration and noise were particularly large. After observation and analysis, it was found that the problem was mainly caused by On the paper roller. When the paper-handling drum opens its teeth, the impact force of the open tooth roller and the open tooth block is too large, causing serious vibration and noise. Here, the open-tooth plate curve is the same as the traditional model, and it is a smooth connection with three arcs. Why is the impact force so large? After analysis and calculation, it was found that the open tooth form was caused by different forms of open teeth. The traditional form of open teeth is that the center of the roller is behind the center of the dental shaft (normal operation), the open plate is installed between the roller and the center of the cylinder, and the open roller on the double-sided printing machine is in front of the center of the dental shaft. Open the teeth in the outer circumference of the open teeth roller. Due to the large distance between the open tooth roller center and the open tooth surface, the open tooth pressure angle is very small (about 21°), and the open tooth force is decomposed into a tangential force Ft (the force needed to open the tooth) and a normal force Fr. (The force acting on the connecting line between the center of the open tooth roller and the center of the tooth shaft). It can be seen that the force Ft is small and the force Fr is larger. When the machine is running, the open tooth roller collides with the open jaw and generates a lot of vibration and noise. In order to change the form of the open teeth of the roller, it is necessary to change all the mechanisms and corresponding control mechanisms of this part. The workload is large and it will cause great losses. After research and analysis, it was decided that the breakthrough point for solving the problem was to change the curve of the open tooth plate, that is, to change the open tooth acceleration curve.

Three-arc curve can not meet this need, you must find another curve, the new curve of the original equation is:

¢=¢. ×{1-COS(πδ/δ.)}

¢--The axis angle of the gripper;

Hey. -- The total swing angle of the gripper shaft;

δ - open teeth interval roller angle;

δ. - The total rotation angle of the roller in the open area.

The coordinate transformation is used to transform the equation of angular relationship into an equation in a Cartesian coordinate system, as follows:

X=Rcos(A-δ)+rsin(B+¢+δ)

y=Rsin(A-δ)+rcos(B+¢+δ)

x, y - the coordinates of the center of the open roller against the center of the drum;

R - center distance between gripper shaft and cylinder;

r - the center distance between the open tooth roller and the gripper shaft;

A--the initial position angle of the center of the shaft;

B--the angle between the open position of the open rocker and the negative direction of the X axis.

This equation is an equation for the center of an open tooth roller. Using a computer to trace out the movement track of the center of the open tooth roller, obtain the curve of its movement trajectory, use the envelope method to obtain the actual open tooth curve of the tooth plate, and after the correction, a complete open tooth curve is obtained. The open cutting board machined on this curve is mounted on the machine. The vibration and noise are within the allowable range at a speed of 8500 rpm. Another way to open teeth, high point closure, is using this method. Vibration and noise are controlled within the scope of the license. If colleagues have similar circumstances, they may wish to use this method to try.