The assembly of rolling bearings should be determined based on the structure, size, and compatibility of the bearing components. The general assembly methods for rolling bearings include hammering, pressing, hot fitting, and cold shrinking.
1. Preparation work before assembly of rolling bearings
(1) Prepare the necessary tools and measuring tools according to the bearings to be assembled. Inspect the parts that match the bearings according to the drawing requirements for defects, rust, and burrs.
(2) Clean the parts that match the bearings with gasoline or kerosene, wipe them clean with a clean cloth or blow dry with compressed air, and then apply a thin layer of oil.
(3) Check if the bearing model is consistent with the drawing.
(4) Bearings sealed with rust proof oil can be cleaned with gasoline or kerosene; Sealed with thick oil and rust proof grease, light mineral oil can be heated, dissolved, and cleaned. After cooling, it can be cleaned with gasoline or kerosene, wiped clean, and ready for use; For bearings with dust covers, sealing rings, or coated with rust proof and lubricating grease on both sides, cleaning is not necessary.
2. Assembly method for rolling bearings
(1) Assembly of cylindrical hole bearings
① Non separable bearings (such as deep groove ball bearings, self-aligning ball bearings, self-aligning roller bearings, angular contact bearings, etc.) should be assembled in order to determine the tightness of the seat ring fit. When the inner ring fits tightly with the shaft neck and the outer ring fits loosely with the housing, first install the bearing on the shaft, and then install it together with the shaft into the housing. When the outer ring of the bearing is in a tight fit with the housing hole and the inner ring is in a relatively loose fit with the shaft neck, the bearing should be pressed into the housing first; When the inner ring is tightly fitted to the shaft, and the outer ring is tightly fitted to the housing hole, the bearing should be pressed onto both the shaft and the housing hole simultaneously,
② Due to the fact that the inner and outer rings of separated bearings (such as tapered roller bearings, cylindrical roller bearings, needle roller bearings, etc.) can freely detach, the inner ring and rolling element are installed together on the shaft during assembly, and the outer ring is installed in the housing, and then the clearance between them is adjusted.
The commonly used assembly methods for bearings include hammering and pressing. Use a specially designed sleeve to press the person, and use a copper rod to symmetrically tap the person evenly on the end face of the bearing inner ring (or outer ring). The method of pressing the inner and outer rings of the bearing into the journal and bearing seat holes using the pressure method.
If the journal size is large and the interference is also large, for the convenience of assembly, the hot fitting method can be used. That is, the bearing is heated in oil at a temperature of 80-100 ° C, and then matched with the shaft at room temperature. When heating the bearings, they should be placed on the grid inside the oil tank to avoid contact with the bottom of the box, which is much higher than the oil temperature, and to prevent contact with accumulated dirt at the bottom of the box. For small bearings, they can be hung on a hook and immersed in oil for heating. Bearings filled with lubricating grease and dust covers or sealing rings inside cannot be assembled using hot fitting method.
(2) When the assembly interference of the tapered hole bearing is small, it can be directly installed on the tapered journal, or on the tapered surface of the tightening sleeve or the retracting sleeve; For tapered hole bearings with large journal dimensions or large fit interference and frequent disassembly, hydraulic sleeve method is commonly used for disassembly.
(3) The assembly of thrust ball bearings There are two types of thrust ball bearings: loose ring and tight ring. During assembly, the tight ring should be placed against the end face of the rotating part, while the loose ring should be placed against the end face of the stationary part. Otherwise, it will cause the rolling element to lose its function and accelerate the wear between the mating parts.
3. Method for detecting errors in rolling bearing assembly parts
For spindle components with high precision requirements, in order to improve the rotational accuracy of the spindle, directional assembly is often used when assembling the inner ring of the bearing with the spindle and the outer ring of the bearing with the housing hole. Directional assembly is a method of artificially controlling the radial runout direction of various assembly components, combining them reasonably, and using error cancellation to improve assembly accuracy. Before assembly, it is necessary to measure the deviation of the centerline of the tapered hole at the end of the spindle shaft and the radial runout of the inner and outer rings of the bearing, determine the direction of the error, and mark it properly.
(1) Detection of radial runout of the outer ring of the bearing. When measuring, rotate the outer ring and press it in the direction of the dial gauge. The large reading on the dial gauge indicates the radial runout of the outer ring.
(2) Detection of radial runout of bearing inner ring. When measuring, the outer ring is fixed and does not rotate, and a uniform measurement load F is applied to the end face of the inner ring. The value of F varies according to the type and diameter of the bearing, and then the inner ring is rotated for more than one revolution to measure the radial circular jumping momentum and direction of the inner hole surface of the bearing inner ring.
(3) Detection of the centerline of the spindle cone hole. When measuring, place the spindle journal on a V-shaped frame, insert the measuring mandrel into the spindle cone hole, and rotate the spindle more than one turn to measure the deviation value and direction of the centerline of the cone L.