Some standard content:
Machinery Industry Standard of the People's Republic of China
JB/T7557—94
Coaxiality Error Detection
Published on December 9, 1994
Ministry of Machinery Industry of the People's Republic of China
Implementation on October 1, 1995
Subject Content and Scope of Application
Cited Standards
Method for Determining the Minimum Containment Area of Coaxiality
Detection Method
Data Processing
Appendix A
Appendix B
Single-point criterion
Embodiment of the reference axis (reference)
Application example of coaxiality error detection (reference)
Mechanical Industry Standard of the People's Republic of China
Coaxiality error detection
Subject content and scope of application
JB/T7557-94
This standard specifies the terminology, minimum inclusion area judgment method, detection method and data processing method for coaxiality error detection. This standard is applicable to the coaxiality error detection of parts elements in mechanical industry products. This standard supplements and specifies the coaxiality error detection in GB1958. 2 Reference standards
GB1183
GB1958
GB8069
GB11336
3 Terms
3.1 Ideal axis
Form and position tolerance
Form and position tolerance
Position gauge
Straightness error detection
Terms and definitions
Detection regulations
It can be the minimum area rotation surface axis, the least square rotation surface axis, the minimum circumscribed rotation surface axis and the maximum inscribed rotation surface axis, etc.
3.2 Datum axis
The ideal axis of the rotation surface of the actual datum element, 3.3 Common datum axis
The ideal axis of the rotation surface of two or more actual datum elements. 3.4 Normal section
The section perpendicular to the ideal axis.
3.5 Actual measured axis
The actual measured axis is the line connecting the center points of the contours of the actual measured face. The wheel center point is the centroid of the ideal circle of the wheel. The ideal circle can be determined by the minimum area method, the least squares method, the minimum circumscribed circle method and the maximum inscribed circle method. Note: When evaluating the coaxiality error, the measured line is used instead of the actual measured axis. 3.6 Minimum coaxiality inclusion area
The area within the cylindrical surface with the smallest diameter that contains the actual measured axis with the reference axis as the axis (see Figure 1). 3.7 Coaxiality error value
The diameter of the minimum inclusion area of the coaxiality.
3.8 Measurement reference line
The reference line for obtaining the measured value during the measurement process. Note: For other related terms, see GB1183 and GB1958. Approved by the Ministry of Machinery Industry on December 9, 1994 and implemented on October 1, 1995. Method for determining the minimum coaxiality inclusion area: JB/T7557-94. Minimum coaxiality inclusion area. In the single-point criterion, the cylindrical surface with the reference axis as the axis contains the actual measured axis. When the actual measured axis has at least one point in contact with the cylindrical surface, the area within the cylindrical surface is the minimum coaxiality inclusion area. See Figure 2. The minimum inclusion area of axial error is
reference axis
actual line
Detection method
Classification of detection methods
The detection methods of coaxial error can be divided into the following categories a.
rotation axis method;
collimation method (targeting method):
coordinate method;
top method:
V-shaped frame method
simulation method:
gauge inspection method.
JB/T755794
The measurement accuracy of various detection methods is determined by the accuracy of the measuring instrument used, the method for determining the reference axis and the data processing method. The following detection method example is just an example of this detection method. 5.2 Rotation axis
This method uses detection instruments with higher rotation accuracy (such as roundness tester, columnarity tester, etc.), which is suitable for measuring the coaxiality error of medium and small-sized shafts or hole parts. See Figure 3. Measurement steps:
Adjust the measured part so that its axis is coaxial with the rotation axis of the instrument spindle: measure on the actual reference cable and the actual measured element of the measured part, record data or (and) record wheel graphics; c.
According to the measured data or recorded wheel sense graphics, determine the rotation error of the measured cable according to the coaxiality error judgment criteria and data processing method.
5.3 Collimation method (target aiming method)
This method uses detection instruments such as collimation telescopes or laser collimators, which is suitable for measuring the coaxiality error of large and medium-sized hole parts. See Figure 4.
Measurement steps:
According to the diameter of the hole to be measured, different supporting tools are used to make the center of the target coincide with the center of the circle of the hole to be measured: Use the collimated optical axis of the instrument as the measurement reference line to adjust the position of the measuring instrument so that the connecting line of the center of the target at both ends of the measured part is coaxial with the optical axis. Perform step a in the reference hole, and measure the X and Y coordinate values of each point on the actual reference axis through the optical collimation system; Perform step a in the measured hole, and measure the X and Y coordinate values of each point on the actual measured axis through the optical collimation system: d.
According to the measured X and Y coordinate values of each point on the actual reference axis and the actual measured axis, determine the coaxiality error of the measured target e.
through data processing.
5.4 Coordinate method
This method uses a detection instrument with a determined coordinate system (such as various types of three-coordinate measuring machines, universal measuring microscopes, etc.), which is suitable for measuring the coaxiality error of parts of various specifications. See Figure 5. Measuring steps:
Place the measured part on the workbench;
JB/T7557-94
Measure the datum plan and measured elements of the measured part: Calculate the position of the datum axis and the coordinates of the center point of the wheel of each positive cutting surface of the measured element according to the measured data, and then determine the coaxiality error of the measured part through data processing.
Measured workpiece, 3-collimation medium moving mirror
5.5 Center method
This method is suitable for the coaxiality error measurement of shaft parts and disk sleeve parts (with a mandrel with a center hole). See Figure 6. Measuring steps:
Mount the measured part on the two centers of the measuring instrument: Determine the position of the datum axis according to the selected datum axis embodiment method; Measure the radius difference of the contour of each positive cutting surface of the actual measured element, and calculate the coordinates of the center point of the wheel seat; Determine the coaxiality error of the measured element according to the position of the datum axis and the measured scene values of each point on the actual measured axis. 5.6 V-shaped frame method
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JB/T7557-94
1-dividing plate, 2-indicator: 3-test workpiece This method is suitable for measuring the coaxiality error of parts of various specifications. See Figure 7. Measuring steps:
Place the measured part on the V-shaped frame:
Determine the position of the reference axis according to the selected reference axis expression method: Measure the radius difference of each positive section contour of the actual measured element, and calculate the coordinates of the center point of the circle: According to the position of the reference axis and the measured values of each point on the actual measured axis, determine the coaxiality error of the measured element, Figure 7
1-Measured workpiece, 2-Indicator, 3V-shaped frame 5.7 Simulation method
JB/T7557-94
This method uses a revolving surface with a sufficiently accurate shape to reflect the reference axis, which is suitable for measuring the coaxiality error of medium and small-sized parts.
5.7.1 Use a cylindrical mandrel with sufficient shape accuracy to reflect the reference axis and the measured axis of the hole (as shown in Figure 8). Measuring steps:
Place the part to be measured on a flat plate; bZxz.net
Insert the mandrel into the hole with no clearance, and adjust the part to be measured so that its reference axis is parallel to the flat plate; measure at two points A and B of the hole to be measured, and calculate the differences fax and Fx between the two points and the height (L+d/2) respectively: turn the part to be measured 90°, and measure and FByd according to the above method.
The coaxiality error at point A is f=2(()+(Ax) and the coaxiality error at point B is f=2[(fx)+(f ex）\Take the larger value as the coaxiality error value of the measured part. Note: If the measuring point cannot be taken at the end of the hole, the coaxiality error can be converted in proportion. Figure 8
1 Spindle: 2-Measured workpiece: 3-Indicator 5.7.2 Use a cylindrical sleeve with sufficient shape accuracy to reflect the reference axis of the shaft (as shown in Figure 9). Measurement steps:
a, put the detection device with a cylindrical sleeve on the reference element of the part, and make the device and the reference element form a minimum external connection state and can rotate flexibly:
b.Adjust the indicator on the detection device so that it is in the position of the positive section and in contact with the measured element: c.
Rotate the sleeve, measure the radius difference of the wheel wrist of each positive section of the measured element, and calculate the coordinates of the center point of the contour; d. According to the measured values of each point on the actual measured axis, determine the coaxiality error of the measured element. Note: When the roundness error of the measured element is small enough, the radial runout value of each positive number of the measured element can be measured, and the largest one can be used as the approximate value of the coaxiality error.
Gauge inspection method
Gauge inspection method see GB8069.
Data processing
JB/T755794
1- sleeve, 2- indicator; 3- measured workpiece To measure the coaxiality error, the datum line must be measured first to determine the position of the datum line, then the radius difference of each measuring point on each positive section of the measured element is measured, and the center of each positive section is calculated to determine the coaxiality error value. Then, the coaxiality error value is determined by the minimum inclusion area judgment method of the coaxiality
6.1 Determination of datum axis
After measuring the values of each measuring point on the rotational surface of the datum element, the axis of the rotational surface with the smallest area of the datum line, the axis of the rotational surface with the least squares, the axis of the rotational surface with the smallest circumscribed area, or the axis of the rotational surface with the largest inscribed area can be calculated as the datum axis according to the selected method. The parameter equation of the datum axis is expressed as formula (1): 1=X. +z
y=Y. +
武中：文,
the mark of each point on the datum axis;
X..Y..pq-
the coefficient of the equation of the datum axis.
For the approximate determination method of the datum axis, see Appendix A (reference). 6.2·Determination of the coordinates of the center points of each positive surface wheel of the actual measured element After measuring the radius difference Ar of each measuring point on a positive section of the measured element (i=1,2, the method determines the center mark of the wheel. See Figure 10. 6.2.1 Determine the center according to the minimum area method
Calculation steps:
and, and are the number of excitation points), you can press different a. Take the measured data △r as the initial value, take the measurement center o as the initial center, find out the maximum and minimum values Ar., Ar and their difference in r.
b. Move the center 0 to on according to a certain optimization method: Calculate the radius difference △R of each point after moving the center according to formula (2)
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