Definition
Clearance fit, interference fit and transition fit can be formed according to different relative position relations of combined hole and shaft tolerance zone. Among them. A fit with an interference (including a minimum interference equal to zero) is called an interference fit. In this case, the tolerance zone of the hole is under the tolerance zone of the shaft, and the algebraic difference between the hole size and the shaft size is negative. In the standard, the maximum (small) clearance in various fits is called the limit clearance, and the maximum (small) interference is called the limit interference. The limit clearance and the limit interference respectively reflect the allowable clearance or the variation limit of interference in the hole shaft combination.
Characteristic
The characteristics of interference fit connection are simple structure, good for neutral, large bearing capacity, small strength weakening for shaft and hub, and good impact resistance. Its disadvantage is that it requires high machining accuracy of mating surface, bearing capacity and assembly stress are sensitive to actual interference, and it is not convenient to assemble and disassemble. The interference fit connection is mainly used for the connection between the shaft and the hub, the connection between the wheel rim and the wheel core, and the connection between the rolling bearing and the shaft or the bearing seat hole, etc.
Cooperation status
Loosest state
The difference between the maximum limit size of the hole and the minimum limit size of the shaft is the minimum interference Ymin, which is the most loose state of the hole shaft fit.
Most compact state
The difference between the minimum limit size of the hole and the maximum limit size of the shaft is the maximum interference ymax, which is the most tight state of the hole and shaft.
Assembly method
Temperature difference assembly method. The main working principle of temperature difference assembly method is that due to the different manufacturing materials of parts, the expansion and contraction rates of parts are different, Therefore, when assembling the mechanical parts, we can use the ultra-low temperature of the industrial freezer to make the parts shrink, so that the parts can reach the “easy assembly value” required by the mechanical assembly, so that in the process of installation, the parts can be installed in the machinery without the help of the mechanical function, and only with a small force, so as to improve the mechanical parts Assembly efficiency.