The control part of melt metering pump is usually composed of frequency conversion motor, gearbox, transmission shaft and so on. It is necessary to find the concentricity between the input shaft and the output shaft of the metering pump manually during the installation process. The deviation of the concentricity is compensated by universal coupling. This method can allow a greater degree of concentricity. The offset can be compensated in the range of 10 to 15 degrees between the axle center line of the metering pump and the axle center line of the gearbox in general, and the driving torque will not increase.
But this compensation method also has a disadvantage: the greater the space intersection angle of the two axes, the worse the synchronization between the angular velocity of the driving shaft and the angular velocity of the output shaft of the gear box, that is, the output shaft of the gear box rotates uniformly, and the rotation speed of the input shaft of the most melt metering pump increases with the above-mentioned intersection angle. The more uneven the rotational speed is, the normally controlled angle of intersection is between 0.5 and 10 degrees during installation. But sometimes because of the frame deformation, installation of artificial errors, fixed part loosening and other reasons to make the angle of the larger situation, this situation is not easy to be found.