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Abstract: The original method for verifying the groove position of ball bearings has limitations, especially for complex shaped rings, making it more difficult to measure the groove position. In response to this situation, improvements have been made to the original measurement method, enhancing its applicability, measurement efficiency, and accuracy. Not only can it be applied to calibrate standard parts for groove position, but it can also be used to directly measure the groove position of certain special groove shaped parts on the machining site.
Keywords: Rolling bearings; Channel location; Measuring instrument; Standard parts; improvement
In the machining and inspection process of ball bearing grooves, the position of the groove is one of the important inspection items, and usually instruments or samples are used for comparative measurement. The instrument measurement method is mainly carried out on instruments of the same types as D012 (outer groove) and D022 (inner groove). During measurement, one position standard piece needs to be calibrated in advance as a comparison sample. The verification of position standard parts requires the use of height standard parts for indirect measurement. Although this verification method is simple and easy to implement, it has defects such as incomplete measurement accuracy and difficulty in measuring bearings with special structural shapes. Therefore, it is necessary to improve this calibration method to improve measurement accuracy and expand its application range.
1. Original calibration method
The original calibration method is shown in Figure 1. Before measurement, select one steel ball of the same size as the finished bearing, one height gauge, and a value H close to the bearing groove position.
Firstly, measure the total height H1 (H1=h+Dw) of the steel ball and height standard component, and make the measuring needle indicate a measurement point in the middle of its range as the reference zero point; Then, move the steel ball to the bottom of the bearing groove, adjust the bearing ring and the steel ball so that the gauge needle contacts the highest point of the steel ball, check the position indicated by the gauge needle, and record the actual height value at this time as H2; The difference between the two indicated values is denoted as δ=Å H1-H2 Å (when H1>H2, take "-"; when H1<H2, take "+"), then the actual channel position H=H1-Dw/2 ± δ=h+Dw/2+H2-H1.
The above calibration method is simple and easy to operate, but there are certain problems: (1) Due to the steel ball radius being smaller than the groove curvature radius, the positioning of the steel ball is prone to instability and deviation in actual operation, resulting in measurement errors; (2) For measurements of irregular groove shapes and positions (such as asymmetric grooves in angular contact bearings and non-standard bearing parts with deeper grooves), it is difficult for steel balls to accurately locate them; (3) The tip surface of the testing instrument is too small, making it easy to swing during the measurement process, making it difficult to accurately locate the highest point of the steel ball when in direct contact with the surface of the object being measured. From this, it can be seen that this method has problems of inconvenient operation and low measurement efficiency, requiring high technical level and experience of operators, and is prone to human measurement errors, which need to be improved.
1- Measurement platform; 2- Samples to be inspected; 3- Height standard parts; 4- Steel ball standard parts; 5- Instrumentation
Figure 1 Original measurement method
2. Improved calibration method
The improved calibration method is shown in Figure 2. The measurement steps are as follows: (1) Adjust the height of the gauge holder according to the diagram, so that the measuring point position H1 of the test gauge rod is close to the bottom position H of the bearing ring groove, and the difference between the two is recorded as δ=æ H-H1 æ. Adjust the position indicated by the gauge tip of instrument 1, using the middle position indicated by the gauge needle to the instrument range as a reference point; (2) Select a height standard block with a height dimension close to the position dimension of the bearing groove to be measured, and compare instrument 2 with the middle position of the gauge range indicated by the gauge needle as the reference zero position; (3) Adjust the adjustment screw to move the entire measuring frame up and down. Observe the movement position of the gauge needle in instrument 1. When the gauge needle reaches a limit position during reciprocating movement, stop rotating the adjustment screw. At this time, the position indicated by the tip of the test gauge rod is the bottom position of the bearing groove; (4) Check the new position indicated by the needle of instrument 2, calculate the number of scales rotated compared to the original position, and record it as δ '. Due to the fact that two instruments share the same stand, their movement distance is equal, i.e. δ=δ '. The position dimension of the bearing groove is H=H '± δ=H' ± δ '(when H>H', take "+"; when H<H ', take "-").
1- Measurement platform; 2- Samples to be inspected; 3- Measuring gauge rod; 4- Instrument 1; 5- Instrument guide pillar; 6- Adjust the screw; 7- Meter stand; 8- Instrument 2; 9- Height standard parts
Figure 2 Improved measurement method
This method can provide more accurate verification of the groove position of bearings, and can also measure the groove position of certain special structured bearings (which cannot be measured with commonly used instruments).
3. Application effect
To verify the effectiveness of the improved instrument, different specifications of bearing rings were selected as samples, and three measurement methods were used: professional precision instrument (clearance gauge), simple instrument before improvement, and improved instrument for groove position size verification. The measurement results are shown in Table 1.
Table 1 Comparison of measurement data
From the data in the table, it can be seen that the improved measurement method can meet the accuracy requirements of the on-site process and can achieve simple calibration of standard parts for trench positions. In addition, this method has a simple structure and simple operation, and can be directly used as a conventional instrument to measure the grooves of bearing parts (especially products with complex grooves and difficult to measure with conventional instruments). Moreover, this instrument is economically applicable and can greatly reduce measurement costs compared to specialized precision instruments.
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2024-07-12