Cam indexer, also known as intermittent splitter, in recent years, with the increase in labor costs, automated machinery instead of labor has become the trend of future development, and as the core component of automated machinery precision cam indexer is gradually familiar to people, it has accurate indexing, smooth motion curve, high-speed mechanical properties and other characteristics, in automated assembly, packaging, food industry, pharmaceutical industry and other everywhere can see its figure.
The working principle of the cam indexer is that the conjugate cam on the input shaft and the index plate with evenly distributed needle roller bearings on the output shaft are vertically meshed without clearance, and the curve segment of the cam contour surface drives the needle roller bearing on the index plate to drive the index plate to rotate, and the straight line segment makes the index plate stationary, and the positioning is self-locking. Under normal circumstances, the input shaft rotates a circle (360°), and the output shaft completes a indexing process of one movement and one stop, in an indexing process, the output shaft has a ratio of indexing time and stopping time called the dynamic and static ratio, and the size of the dynamic and static ratio is related to the angle that the cam curve segment occupies in the whole cam circumference (usually the angle occupied by this curve is called the driving angle), the larger the driving angle, the larger the ratio, and the more stable the splitter runs; The angle occupied by the straight section on the cam circumference is called the angle of rest, and the sum of the angle of motion and the angle of rest is 360°. The number of stations of the cam indexer (i.e., the number of stations N obtained by dividing the angle Θ of each transfer of the output shaft by 360°, 360°÷Θ=N). The number of stations N is related to the number of needle roller bearings loaded on the index plate of the output shaft, under normal circumstances, the number of needle roller bearings on the index dial is the same as the number of stations, and the following situation occurs when station N ≤ 4: when N = 4, the number of needle roller bearings on the index dial is 2N (2 needle roller bearings are toggled at each stroke angle): when the number of stations N=2, the needle roller bearings on the index dial are 3N, and the cam curve toggles 3 needle roller bearings each time; When the number of indexing degrees N is too large, due to the size of the diameter of the indexing plate, too many needle roller bearings can not be installed, the cam curve is generally segmented, and the same straight line is also segmented (but the curve form may also change), so that the number of needle roller bearings is too large, and the diameter of the distribution is too small to affect the load of the splitter. The commonly used cam curves are: MS (variable sinusoidal curve), MT (variable trapezoidal curve), MCV50 (variable constant velocity curve), and one strand preferential MS (variable sinusoidal curve).
The indexing accuracy of the output shaft of the cam indexer (repeated positioning accuracy, that is: the angle error of the conversion from one station to the next station) is determined by the position error between the evenly distributed needle roller bearings on the index plate, the smaller the position error between the needle roller bearings on the index plate, the higher the indexing accuracy of the splitter, and vice versa, the general indexing accuracy is divided into three levels, ordinary grade ≤±50", precision grade ≤±30", high precision grade ≤±15".
Whether the rotation process of the cam indexer (i.e., the station conversion process and the stop state) is stable, and the indexing accuracy of the index plate and the machining accuracy of the cam curve and the surface roughness of the cam curve are related, because the meshing between the cam and the index plate is a gap-free mesh, so the uneven indexing of the needle roller bearing on the index plate will produce some gaps between the needle roller bearing and the cam curve surface, and some may produce excessive pressure. During the working process of the splitter, shaking occurs under the action of the moment of inertia. When the surface roughness of the cam curve is too large, the needle roller bearing will produce vibration when rolling on the cam curve surface, which will also be transduced to the output shaft and the corresponding station plate, which will affect the yield of the workpiece in the production process of the equipment.