For example, in a roller conveyor driven by double chain teeth, how to determine the center distance between the rollers?
Of course, the center distance should be initially determined according to the structural requirements.However, the center distance required by the structure does not necessarily conform to the result of the chain link length calculation, so it is necessary to adjust the center distance size according to the actual number of chain links after the calculation is completed.The number of chain links after rounding should be an even number, this is to avoid transition links. With transition links, the load that can be endured is about 20% smaller.
The number of teeth of the left and right sprockets is the same, and the sum of the number of chain links meshing with the two sprockets at any time is equal to the number of teeth Z of one sprocket, so when calculating the chain length, it is only necessary to ensure that the center distance C=N*P/2 (where N is an integer, and P is the chain pitch). To avoid using transition links, L=(Z+N) should be an even number.
However, in most cases, the number of teeth of the two sprockets is not equal. As shown in the figure below, if the sprocket tensioning mechanism is not allowed to be arranged in the structure, how to calculate the length of the chain!
The following is the calculation formula:
L=2C/P+(Z+z)/2+KP/C; L=chain length (in pitch);
Among them: C represents the center distance, P = chain pitch, Z = the number of teeth of the large sprocket, z = the number of teeth of the small sprocket, and K = the coefficient corresponding to Zz (there is a table, you can check the mechanical design manual).
When Z=z, the coefficient K=0 is obtained by looking up the table, that is, the special situation when the sprockets on both sides are equal as mentioned above occurs.That is, the chain length L=2C/P+Z
In practical application, in order to make the chain buckle easy to install, the center distance is generally reduced appropriately, and the reduction ratio is 0.002~0.004C, that is, the actual value is 0.2%~0.4% smaller than the theoretical value.