Axial positioning of parts on the shaft: the axial positioning method of parts on the shaft mainly depends on the magnitude of the axial force. In addition, factors such as the manufacturing of the shaft, the difficulty of assembling and disassembling the parts on the shaft, the impact on the shaft strength and the working reliability should also be considered.
Common axial positioning methods include: shoulder (or collar), sleeve, round nut, retaining ring, conical shaft head, etc.
(1) Shoulder: The shoulder consists of a locating surface and a fillet. To ensure that the end face of the part can be close to the locating surface, the fillet radius of the shaft shoulder must be less than the fillet radius or chamfer height of the hub hole of the part; To ensure sufficient strength to bear axial force, the height of shaft shoulder is h=(2-3) R.
(2) Collar: the function and dimension parameters of the collar are the same as the shoulder, and the width b ≥ 1.4h. If the shaft ring blank is forged, it will use less materials and light weight. If it is made of round steel blank, it will waste materials and processing time.
(3) Shaft sleeve: the shaft sleeve is positioned with the help of the parts whose position has been determined. The two end faces of the shaft sleeve are positioning surfaces, so it should have high parallelism and verticality. In order to ensure reliable positioning of parts on the shaft, the length of the shaft section shall be 2~3mm longer than the hub of the part. The use of shaft sleeve can simplify the structure of shaft and reduce stress concentration. However, due to the loose fit between the shaft sleeve and the shaft, it is difficult for them to be concentric, so they should not be used on the high-speed shaft to avoid unbalanced force.
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