VISTA Technology Knowledge: Detection of Outer Ring Groove Diameter of Four Point Contact Ball Bearing

Processing process of outer ring of four point contact ball bearing, groove diameter inspection after outer ring grinding and the advantages of inspection method.

Abstract: through the analysis of the processing technology and design size of the outer ring of four point contact ball bearing, an ideal method for quickly and accurately inspecting the groove diameter and position of the outer ring of this kind of bearing is introduced.

Key words: four point contact ball bearing; outer ring; ditch diameter; testing

Compared with deep groove ball bearings with the same overall dimensions, four point contact ball bearings can not only bear larger radial loads, but also bear larger axial loads. However, the design, manufacture and inspection of four point contact ball bearings are much more complicated than deep groove ball bearings, especially the inspection of outer ring groove diameter. Combined with the processing of the outer ring, this paper expounds the inspection method of the outer ring groove diameter.

1. Processing process of outer ring of four point contact ball bearing

The outer ring groove of four point contact ball bearing has a double arc structure, as shown in Figure 1.

Fig.1 Schematic diagram of outer ring channel structure

The processing process of the outer ring is: forging blank rough turning, heat treatment, grinding and ultra-precision. Because the outer ring of the four point contact ball bearing needs to be processed into a double arc groove, it cannot be trimmed to the required shape by using the ordinary grinding wheel dressing method. In order to trim the double arc shape, the secondary trimming method must be adopted, that is, after the grinding wheel is trimmed into the single arc re shape with a diamond pen, the grinding wheel is moved along the axial direction for a certain displacement, and then the required shape can be obtained. This method is suitable for small batch production. When mass production, diamond roller can be used to trim to obtain the required shape.

2. Groove diameter inspection after outer ring grinding

The groove shape of the outer ring can be easily guaranteed by grinding wheel dressing or diamond roller, but how to ensure the groove diameter has become the focus of processing, because the groove diameter directly affects the fitting rate of product assembly. Generally, the control method of this process is to convert the trench bottom dimension de according to the design dimension D1, take de as the processing and inspection dimension, and indirectly control the design dimension D1. This method is tenable in theory, but there are still defects in practical application, that is, when dressing the grinding wheel with different diamond rollers, the shape of the repaired grinding wheel cannot be exactly the same, because there is an error in the center distance of the two arcs on the contour when the roller is made. At this time, the actual measured dimension De is the same, but the design dimension D1 cannot be guaranteed to be the same. An ideal method for measuring the groove diameter of the outer ring in Figure 2 is introduced below.

2.1 Design and manufacture of standard parts

According to the product design dimension D1, calculate the product process dimension d1, and design the standard part with the groove diameter dimension d1, the groove position dimension a_e, and the groove curvature radius Re (Re=0.515Dw), as shown in Figure 2.

Fig. 2

2.2 Selection and adjustment of inspection instruments

According to the size of product dimension D1, select the corresponding D012 testing instrument, replace its three probes with spherical probes with steel ball diameter of DW, adjust the instrument according to the outer ring testing method of ordinary deep groove ball bearings, and check the table with the above standard parts. In order to avoid size conversion error and eliminate the influence of groove error, the diameter of the probe should be the same as the diameter of the assembled steel ball.

2.3 Inspection of workpiece

The required design dimension D1 and its deviation can be directly detected by measuring the processed workpiece with the above instruments.

3. Advantages of inspection method

(1) The design and manufacture of standard parts are simple, and the measurement is convenient and accurate.

(2) The inspection instrument has good versatility, and there is no need to add other inspection instruments.

(3) This method can quickly and accurately check the design dimension D1, and can eliminate the influence of machining error caused by grinding wheel dressing error or diamond roller manufacturing on the design dimension.

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