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Shanghai Shang Shaft Bearing Quality Inspection Institute Co., Ltd.

Address: 301 Shangxue Road, Jiading District, Shanghai

# Method for measuring the position of rivet holes in cages

2021-09-30 10:00

For**Deep groove ball bearing split half cage**Rivet hole rivetingThe accuracy of the cage determines the structural accuracy of the cage, thus affectingBearing life.With the automation of processing equipment and processing technologyThe improvement of the rivet hole processing accuracy is also improved, in order to verify the rivet.Hole machining accuracy and provide measurement data to guide the machining process.Line**Rivet hole location measurement**.

Usually, a three-coordinate measuring machine is used to measure the hole position.The diameter of rivet hole is less than 0.9mmHalf cage, subject to three-coordinateThe limit of the diameter of the probe and the distance the probe moves in the hole cannot be measured.The hole position is measured in degrees. In order to solve the similar small aperture hole position degree can not bemeasurement problems, try to adopt**three-dimensional optical measuring instrument**proceed**Non-contactMeasurement**The feasibility of the method is verified by experiments and data analysis.

**1 Principle of measurement**

**three-dimensional optical measuring instrument**is set**Optical, Mechanical, Electronic, ComputerImage Processing**technology in one measuring instrument, can be high precision, highEfficiently measure the size, angle and position of various complex workpieces.

**1.1 measurement method and process**

The rivet hole of the separated half cage is processed by outer diameter positioning andUniformly distributed on the surface of the cage, each hole is a reference to each other, through the fixtureFix the half-holder in place on the measuring platform.

**1.1.1 Rough coordinate system**

Place the measured part in the appropriate position on the platform of the three-dimensional optical measuring instrumentfixed. Measure the reference circle according to the processing positioning method and move the lens.To center of reference circle, empty*x*,*y*,*z*Axis coordinates, complete workpiece positioning.

**1.1.2 Refined coordinate system**

Measure a point on the reference circle, according to the diameter of the reference circle.Small array this point 6~12 times and make it evenly cover the whole circumference,The remaining points are automatically measured and the measured points are fitted to a reference circle. SelectTake one of the rivet holes for automatic measurement, the resulting baseQuasi-circle and rivet hole circle structure coordinate system*x*,*y*,*z*Axis, complete with fine constructionStandard system.

**1.1.3 Automatic measurement of rivet holes**

Measure one of the rivet holes, copy the hole measurement method, cutChange to polar coordinates and array this hole. The number of arrays is based on the actual number of holes.Decide, automatically measure all rivet holes.

**1.1.4 Evaluation position degree**

Select one of the holes in the polar coordinate system and click NominalThe polar diameter and polar angle under the polar coordinates of the hole appear after the key is pressed, according to the figureThe paper requires that the theoretical values and tolerances be entered into the corresponding tables, using polar angles.and pole diameter to calculate the position degree. Follow this step to calculate the rest ofHole position degree.

**1.2 Data processing during measurement**

The rivet hole position measurement is calculated based on the deviation of the pole diameter and the pole angle,When measuring, if one of the holes is used as a reference, evaluate the rest.The position of the hole will cause the overall deviation from the nominal value. This is due toThe polar angles of the holes are all deviated from the nominal value, and the split half cage is riveted.In the process of nail hole processing, each hole is based on each other, and one of the holes is made.The evaluation as a benchmark does not meet the actual requirements.

Similarly, the holes that are the reference of each other are measured on the coordinate measuring machine.When the position is measured, one of the holes cannot be used as a reference for evaluation.price, but because each hole can move a certain angle in series, it can pass throughThe rotation of the coordinate system is evaluated, and the principle of rotation follows the 1/2 tolerance principle.Then.However, the three-dimensional optical measuring instrument cannot rotate the coordinate system,The decision to adopt after the study**polar angle correction**methods for evaluation, correctionThe parameter is 1/2 of the maximum polar angle deviation.

If the rivet hole of the split cage half is 10 equal parts, the rivetNominal value of hole polar angle*α*=360°/10=36°。Set rivet after measurementThe polar diameter and polar angle of each hole are respectively*D*_{i},*β*_{i}, the polar angle of each hole deviatesPoor*θ*_{i}For

Corrected value of polar angle deviation*D d d.*For

According to the conversion of rectangular coordinate system and polar angle coordinate systemDepartment,Use the corrected polar angle and polar diameter for position degree*φ*the evaluationThe price, I .e.

Where:*r*_{0}is the nominal value of the pole diameter.

According**(3) The position degree obtained by the formula is the actual required position.setting degree**, the measured value can reflect whether the hole position is qualified and usedGuide the actual processing.

**2 Test verification and result analysis**

The rivet hole diameter of a bearing half cage is 0.7mm, 14 equal parts, the nominal size of the center diameter is (41.9±0.04)mm, and the positionDegree requirement is 0.03mm. by uncorrected measurement results (Table 1)It can be seen that any hole is selected as the benchmark for evaluation, and the remaining holes change regularly. The position of the benchmark hole is small, and it increases in turn and then becomes smaller.

In order to verify the reliability of this method, the bearing of this type is half-guaranteed.Repeat the measurement of the position of the holder hole for 10 times, and calculate the measurement data.Mean and Standard Deviation, the results are shown in Table 3:14 hole position measurementThe standard deviation of the value is up to 0.001mm, the discreteness is low, the measurementThe value is reliable; the uncertainty of the measured value does not exceed 0.003 0.mm, as well.It shows that the measured value of this method is accurate and reliable.

**3 Concluding remarks**

By studying the measurement of rivet holes in the separation type half cageLi, combinedThe three-coordinate measuring machine is the measuring party of the position of the reference hole.Law, in1/2 maximum polar angle deviation on three-dimensional optical measuring instrumentCorrection methodrealizedMeasurement of Hole Position of Separated Half CageQuantity. The effectiveness and feasibility of the method is verified by an example, and the measurement resultsRepeatabilityMeet the maximum allowable error of the instrument, low discreteness, measured valueReliable,Solve the problem that the position of small aperture holes cannot be measured.The method has been applied in actual production measurement.

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