Design method of adjustable clearance rolling ball bearings:

Rolling ball bearings are widely used for their advantages such as low friction resistance, sensitive starting, high efficiency, high rotation accuracy, simple lubrication, and convenient replacement. applied in production and life. However, due to its high manufacturing precision requirements and complex process, the current standard rolling bearings are produced by special machines and manufactured by professional factories. Since the original design seldom considers adjustable links between rigid parts such as the inner ring, outer ring, and rolling elements of the bearing, the important accuracy index of the bearing - radial clearance is mainly guaranteed by machining tolerances. In this way, even if a high-precision machine tool is used to process the bearing parts, it is difficult to achieve the required accuracy by direct assembly due to the inevitable accumulation of errors. Generally, it must be selected by measurement and assembled by grouping assembly method, but the accuracy is still limited, so that the price of high-precision bearings remains high. At the same time, the out-of-tolerance clearance caused by wear and tear of the bearing during use cannot be compensated, which reduces the actual service life and causes waste. With the development of production, there is an urgent need to solve this technical problem. Therefore, through analysis and research, the author finds out the main factors that restrict the accuracy of bearing radial clearance. Then, starting from the reasonable design of the bearing structure, a novel structural form is designed, so that the radial clearance of the bearing can be adjusted conveniently, and the above technical problems are solved. After trial, the effect is better, and now it is briefly introduced.

1. Design ideas, working principle and specific structure

As we all know, to adjust the radial clearance of the bearing, the relative relationship between the outer ring, the inner ring and the rolling elements must be changed. Positional relationship, the intuitive approach is to make the outer diameter of the inner ring or the inner diameter of the outer ring to be changed as needed. For ball bearings, there is a method to process the inner hole of the inner ring of the bearing into a certain taper, and at the same time, the corresponding taper is also processed for the matching journal. After assembly, the position of the inner ring on the shaft is changed by the additional device on the shaft, so that the inner ring is deformed and the outer diameter is changed to adjust the clearance of the bearing. In all fairness, this is a better method and can solve the problem to a certain extent, so it is still used today. But there are also several obvious deficiencies. First, the adjustment amount is limited (even very small), and when the clearance is large, it is powerless. Second, the shaft journal needs to be processed with a high-precision taper, and an additional adjustment device needs to be set up, which makes the shaft manufacturing process complicated. The third is that the inner ring bears a lot of prestress, and it is a circumferential tensile stress, which is extremely detrimental to the bearing strength, and sometimes the inner ring even breaks itself during adjustment. It can be seen that this traditional method is not reasonable and there is a great need for improvement.

Analyzing the bearing structure, it can be seen that the inner ring has already done enough work on this part, and it seems that there is no potential to be tapped. And the rolling element is a piece of iron, obviously unprofitable. Naturally, we turn our attention to the outer circle. But this part is really simple and simple, and it is impossible to start with conventional thinking, and another way must be found. After thinking hard, asking for advice from many sources, and deliberating over and over again, I finally came to a conclusion. I realized that changing the radial clearance of the bearing is like fighting a war. It can not only be forcibly attacked from the front (radial), but also can be taken from the side (axial). The premise is that we must break through the shackles of traditional thinking and the shackles of habitual forces, and we must dare to innovate. Therefore, it is bold to imagine that the outer ring of the bearing is cut along the cross-section and divided into two parts (reverse thinking, simplifying the complexity). The left and right halves can be moved relative to the axial direction, and then the relative axial displacement of the outer ring is converted into the radial displacement of the rolling element by means of the interaction between the special curved surface on the inner ring ballway and the rolling elements, thereby receiving indirect changes in the inner ring. The effect of the radial position between the ring, the outer ring and the rolling element achieves the purpose of adjusting the clearance. Based on this, we can have the following technical solutions: the outer ring of the rolling bearing is changed from an integral type to an axial split combined type, equipped with double-row rolling elements, and supplemented by adjusting gasket sets. The radial clearance of the bearing can be easily adjusted to the required value by increasing or decreasing the thickness of the adjusting shim during assembly, and finally the outer casing is assembled into a whole with a threaded connection. In the same way, when the bearing is worn for a period of time, it is only necessary to appropriately reduce the thickness of the adjusting shim to easily eliminate the bad clearance and restore the original accuracy. achieve the purpose of repair.

2. Features of this design

(1) Easy to process and manufacture: Due to the intermediate adjustable link, the tolerance zone of the machining dimension of the parts can be greatly relaxed, and the reject rate also increases. It doubled down. At the same time, it can reduce the precision requirements of the machine tool, making it possible to process high-precision bearings on ordinary precision machine tools. The technical level of workers can also be appropriately lowered, which has certain economic benefits.

(2) Easy to assemble and install: After the outer ring is made into a separate type, the radial clearance of the bearing can be easily adjusted to the ideal value, and high precision can be achieved without using the group assembly method. The installation on the shaft is also very convenient, and there is no need to add other adjustment devices, which simplifies the structure of the whole machine.

(3) Improve the stress condition: the use of double-row rolling elements can increase the bearing capacity and can withstand bidirectional axial force.

(4) Reduce the types of parts: After the outer ring is made into a separate type, the rolling elements can be fully covered on the fairway, so that the cage can be omitted.